# Yes I know it!

Note: A long update was posted on 12th December 2017, 11:35 IST.

This post is spurred by my browsing of certain twitter feeds of certain pop-sci. writers.

The URL being highlighted—and it would be, say, “negligible,” but for the reputation of the Web domain name on which it appears—is this: [^].

I want to remind you that I know the answers to all the essential quantum mysteries.

Not only that, I also want to remind you that I can discuss about them, in person.

It’s just that my circumstances—past, and present (though I don’t know about future)—which compel me to say, definitely, that I am not available for writing it down for you (i.e. for the layman) whether here or elsewhere, as of now. Neither am I available for discussions on Skype, or via video conferencing, or with whatever “remoting” mode you have in mind. Uh… Yes… WhatsApp? Include it, too. Or something—anything—like that. Whether such requests come from some millionaire Indian in USA (and there are tons of them out there), or otherwise. Nope. A flat no is the answer for all such requests. They are out of question, bounds… At least for now.

… Things may change in future, but at least for the time being, the discussions would have to be with those who already have studied (the non-relativistic) quantum physics as it is taught in universities, up to graduate (PhD) level.

And, you have to have discussions in person. That’s the firm condition being set (for the gain of their knowledge 🙂 ).

Just wanted to remind you, that’s all!

Update on 12th December 2017, 11:35 AM IST:

I have moved the update to a new post.

A Song I Like:

(Western, Instrumental) “Berlin Melody”
Credits: Billy Vaughn

[The same 45 RPM thingie [as in here [^], and here [^]] . … I was always unsure whether I liked this one better or the “Come September” one. … Guess, after the n-th thought, that it was this one. There is an odd-even thing about it. For odd ‘n” I think this one is better. For even ‘n’, I think the “Come September” is better.

… And then, there also are a few more musical goodies which came my way during that vacation, and I will make sure that they find their way to you too….

Actually, it’s not the simple odd-even thing. The maths here is more complicated than just the binary logic. It’s an n-ary logic. And, I am “equally” divided among them all. (4+ decades later, I still remain divided.)… (But perhaps the “best” of them was a Marathi one, though it clearly showed a best sort of a learning coming from also the Western music. I will share it the next time.)]

[As usual, may be, another revision [?]… Is it due? Yes, one was due. Have edited streamlined the main post, and then, also added a long update on 12th December 2017, as noted above.]

/

# Micro-level water-resources engineering—8: Measure that water evaporation! Right now!!

It’s past the middle of May—the hottest time of the year in India.

The day-time is still lengthening. And it will continue doing so well up to the summer solstice in the late June, though once monsoon arrives some time in the first half of June, the solar flux in this part of the world would get reduced due to the cloud cover, and so, any further lengthening of the day would not matter.

In the place where I these days live, the day-time temperature easily goes up to 42–44 deg. C. This high a temperature is, that way, not at all unusual for most parts of Maharashtra; sometimes Pune, which is supposed to be a city of a pretty temperate climate (mainly because of the nearby Sahyaadris), also registers the max. temperatures in the early 40s. But what makes the region where I currently live worse than Pune are these two factors: (i) the minimum temperature too stays as high as 30–32 deg. C here whereas in Pune it could easily be falling to 27–26 deg. C even during May, and (ii) the fall of the temperatures at night-time proceeds very gradually here. On a hot day, it can easily be as high as 38 deg C. even after the sunset, and even 36–37 deg. C right by the time it’s the mid-night; the drop below 35 deg. C occurs only for the 3–4 hours in the early morning, between 4 to 7 AM. In comparison, Pune is way cooler. The max. temperatures Pune registers may be similar, but the evening- and the night-time temperatures fall down much more rapidly there.

There is a lesson for the media here. Media obsesses over the max. temperature (and its record, etc.). That’s because the journos mostly are BAs. (LOL!) But anyone who has studied physics and calculus knows that it’s the integral of temperature with respect to time that really matters, because it is this quantity which scales with the total thermal energy transferred to a body. So, the usual experience common people report is correct. Despite similar max. temperatures, this place is hotter, much hotter than Pune.

And, speaking of my own personal constitution, I can handle a cold weather way better than I can handle—if at all I can handle—a hot weather. [Yes, in short, I’ve been in a bad shape for the past month or more. Lethargic. Lackadaisical. Enervated. You get the idea.]

But why is it that the temperature does not matter as much as the thermal energy does?

Consider a body, say a cube of metal. Think of some hypothetical apparatus that keeps this body at the same cool temperature at all times, say, at 20 deg. C.  Here, choose the target temperature to be lower than the minimum temperature in the day. Assume that the atmospheric temperature at two different places varies between the same limits, say, 42 to 30 deg. C. Since the target temperature is lower than the minimum ambient temperature, you would have to take heat out of the cube at all times.

The question is, at which of the two places the apparatus has to work harder. To answer that question, you have to calculate the total thermal energy that has be drained out of the cube over a single day. To answer this second question, you would need the data of not just the lower and upper limits of the temperature but also how it varies with time between two limits.

The humidity too is lower here as compared to in Pune (and, of course, in Mumbai). So, it feels comparatively much more drier. It only adds to the real feel of a real hot weather.

One does not realize it, but the existence of a prolonged high temperature makes the atmosphere here imperceptibly slowly but also absolutely insurmountably, dehydrating.

Unlike in Mumbai, one does not notice much perspiration here, and that’s because the air is so dry that any perspiration that does occur also dries up very fast. Shirts getting drenched by perspiration is not a very common sight here. Overall, desiccating would be the right word to describe this kind of an air.

So, yes, it’s bad, but you can always take precautions. Make sure to drink a couple of glasses of cool water (better still, fresh lemonade) before you step out—whether you are thirsty or not. And take an onion with you when you go out; if you begin to feel too much of heat, you can always crush the onion with hand and apply the juice onto the top of your head. [Addendum: A colleague just informed me that it’s even better to actually cut the onion and keep its cut portion touching to your body, say inside your shirt. He has spent summers in eastern Maharashtra, where temperatures can reach 47 deg. C. … Oh well!]

Also, eat a lot more onions than you normally do.

And, once you return home, make sure not to drink water immediately. Wait for 5–10 minutes. Otherwise, the body goes into a shock, and the ensuing transient spikes in your biological metabolism can, at times, even trigger the sun-stroke—which can even be fatal. A simple precaution helps avoid it.

For the same reason, take care to sit down in the shade of a tree for a few minutes before you eat that slice of water-melon. Water-melon is nothing but more than 95% water, thrown with a little sugar, some fiber, and a good measure of minerals. All in all, good for your body because even if the perspiration is imperceptible in the hot and dry regions, it is still occurring, and with it, the body is being drained of the necessary electrolytes and minerals. … Lemonades and water-melons supply the electrolytes and the minerals. People do take care not to drink lemonade in the Sun, but they don’t always take the same precaution for water-melon. Yet, precisely because a water-melon has so much water, you should take care not to expose your body to a shock. [And, oh, BTW, just in case you didn’t know already, the doctor-recommended alternative to Electral powder is: your humble lemonade! Works exactly equivalently!!]

Also, the very low levels of humidity also imply that in places like this, the desert-cooler is effective, very effective. The city shops are full of them. Some of these air-coolers sport a very bare-bones design. Nothing fancy like the Symphony Diet cooler (which I did buy last year in Pune!). The air-coolers locally made here can be as simple as just an open tray at the bottom to hold the water, a cube made of a coarse wire-mesh which is padded with the khus/wood sheathings curtain, and a robust fan operating [[very] noisily]. But it works wonderfully. And these local-made air-coolers also are very inexpensive. You can get one for just Rs. 2,500 or 3,000. I mean the ones which have a capacity to keep at least 3–4 people cool.(Branded coolers like the one I bought in Pune—and it does work even in Pune—often go above Rs. 10,000. [I bought that cooler last year because I didn’t have a job, thanks to the Mechanical Engineering Professors in the Savitribai Phule Pune University.])

That way, I also try to think of the better things this kind of an air brings. How the table salt stays so smoothly flowing, how the instant coffee powder or Bournvita never turns into a glue, how an opened packet of potato chips stays so crisp for days, how washed clothes dry up in no time…

Which, incidentally, brings me to the topic of this post.

The middle—or the second half—of May also is the most ideal time to conduct evaporation experiments.

If you are looking for a summer project, here is one: to determine the evaporation rate in your locality.

Take a couple of transparent plastic jars of uniform cross section. The evaporation rate is not very highly sensitive to the cross-sectional area, but it does help to take a vessel or a jar of sizeable diameter.

Affix a mm scale on the outside of each jar, say using cello-tape. Fill the plastic jars to some level almost to the full.

Keep one jar out in the open (exposed to the Sun), and another one, inside your home, in the shade. For the jar kept outside, make sure that birds don’t come and drink the water, thereby messing up with your measurements. For this purpose, you may surround the jar with an enclosure having a coarse mesh. The mesh must be coarse; else it will reduce the solar flux. The “reduction in the solar flux” is just a fancy [mechanical [thermal] engineering] term for saying that the mesh, if too fine, might cast too significant a shadow.

Take measurements of the heights of the water daily at a fixed time of the day, say at 6:00 PM. Conduct the experiment for a week or 10 days.

Then, plot a graph of the daily water level vs. the time elapsed, for each jar.

Realize, the rate of evaporation is measured in terms of the fall in the height, and not in terms of the volume of water lost. That’s because once the exposed area is bigger than some limit, the evaporation rate (the loss in height) is more or less independent of the cross-sectional area.

Now figure out:

Does the evaporation rate stay the same every day? If there is any significant departure from a straight-line graph, how do you explain it? Was there a measurement error? Was there an unusually strong wind on a certain day? a cloud cover?

Repeat the experiment next winter (around the new year), and determine the rate of evaporation at that time.

Later on, also make some calculations. If you are building a check-dam or a farm-pond, how much would be the evaporation loss over the five months from January to May-end? Is the height of your water storage system enough to make it practically useful? economically viable?

A Song I Like:

(Hindi) “mausam aayegaa, jaayegaa, pyaar sadaa muskuraayegaa…”
Music: Manas Mukherjee
Singers: Manna Dey and Asha Bhosale
Lyrics: Vithalbhai Patel

# The goals are clear, now

This one blog post is actually a combo-pack of some 3 different posts, addressed to three different audiences: (i) to my general readers, (ii) to the engineering academics esp. in India, and (iii) to the QM experts. Let me cover it all in that order.

(I) To the general reader of this blog:

I have a couple of neat developments to report about.

I.1. First, and of immediate importance: I have received, and accepted, a job offer. Of course, the college is from a different university, not SPPU (Savitribai Phule Pune University). Just before attending this interview (in which I accepted the offer), I had also had discussions with the top management of another college, from yet another university (in another city). They too have, since then, confirmed that they are going to invite me once the dates for the upcoming UGC interviews at their college are finalized. I guess I will attend this second interview only if my approvals (the university and the AICTE approvals) for the job I have already accepted and will be joining soon, don’t go through, for whatever reason.

If you ask me, my own gut feel is that the approvals at both these universities should go through. Historically, neither of these two universities have ever had any issue with a mixed metallurgy-and-mechanical background, and especially after the new (mid-2014) GR by the Maharashtra State government (by now 2.5+ years old), the approval at these universities should be more or less only a formality, not a cause for excessive worry as such.

I told you, SPPU is the worst university in Maharashtra. And, Pune has become a real filthy, obnoxious place, speaking of its academic-intellectual atmosphere. I don’t know why the outside world still insists on calling both (the university and the city) great. I can only guess. And my guess is that brand values of institutions tend to have a long shelf life—and it would be an unrealistically longer shelf life, when the economy is mixed, not completely free. That is the broad reason. There is another, more immediate and practical reason to it, too—I mean, regarding how it all actually has come to work.

Most every engineer who graduates from SPPU these days goes into the IT field. They have been doing so for almost two decades by now. Now, in the IT field, the engineering knowledge as acquired at the college/university is hardly of any direct relevance. Hence, none cares for what academically goes on during those four years of the UG engineering—not in India, I mean—not even in IITs, speaking in comparison to what used to be the case some 3 decades ago. (For PG engineering, in most cases, the best of them go abroad or to IITs anyway.) By “none” I mean: first and foremost, the parents of the students; then the students themselves; and then, also the recruiting companies (by which, I mostly mean those from the IT field).

Now, once in the IT industry and thus making a lot of money, these people of course find it necessary to keep the brand value of “Pune University” intact. … Notice that the graduates of IITs and of COEP/VJTI etc. specifically mention their college on their LinkedIn profiles. But none from the other colleges in SPPU do. They always mention only “University of Pune”. The reason is, their colleges didn’t have as much of a brand value as did the university, when all this IT industry trend began. Now, if these SPPU-graduated engineers themselves begin to say that the university they attended was in fact bad (or had gone bad at least when they attended it), it will affect their own career growth, salaries and promotions. So, they never find it convenient to spell out the truth—who would do that? Now, the Pune education barons (not to mention the SPPU authorities) certainly are smart enough to simply latch on to this artificially inflated brand-value. The system works, even though the quality of engineering education as such has very definitely gone down. (In some respects, due to expansion of the engineering education market, the quality has actually gone up—even though my IIT/COEP classmates often find this part difficult to believe. But yes, there have been improvements too. The improvements pertain to such things as syllabii and systems (in the “ISO” sense of the term). But not to the actual delivery—not to the actually imparted education. And that‘s my point.)

When parents and recruiting companies themselves don’t care for the quality of education imparted within the four years of UG engineering, it is futile to expect that mere academicians, as a group, would do much to help the matters.

That’s why, though SPPU has become so bad, it still manages to keep its high reputation of the past—and all its current whimsies (e.g. such stupid issues as the Metallurgy-vs-Mechanical branch jumping, etc.)—completely intact.

Anyway, I am too small to fight the entire system. In any case, I was beyond the end of all my resources.

All in all, yes, I have accepted the job offer.

But despite the complaining/irritating tone that has slipped in the above write-up, I would be lying to you if I said that I was not enthusiastic about my new job. I am.

I.2. Second, and from the long-term viewpoint, the much more important development I have to report (to my general readers) is this.

I now realize that I have come to develop a conceptually consistent physical viewpoint for the maths of quantum mechanics.

(I won’t call it an “interpretation,” let alone a “philosophical interpretation.” I would call it a physics theory or a physical viewpoint.)

This work was in progress for almost a year and a half or more—since October 2015, if I go by my scribblings in the margins of my copy of Griffiths’ text-book. I still have to look-up the scribblings I made in the small pocket notebooks I maintain (more than 10 of them, I’ve finished already for QM alone). I also have yet to systematically gather and order all those other scribblings on the paper napkins I made in the restaurants. Yes, in may case, notings on the napkins is not just a metaphor; I have often actually done such notings, simply because sometimes I do forget to carry my pocket notebooks. At such times, these napkins (or those rough papers from the waiter’s order-pad), do come in handy. I have been storing them in a plastic bag, and a drawer. Once I look up all such notings systematically, I will be able to sequence the progression of my thoughts better. But yes, as a rough and ready estimate, thinking along this new line has been going on for some 1.5 years or more by now.

But it’s only recently, in December 2016 or January 2017, that I slowly grew fully confident that my new viewpoint is correct. I took about a month to verify the same, checking it from different angles, and this process still continues. … But, what the heck, let me be candid about it: the more I think about it, all that it does is to add more conceptual integrations to it. But the basic conceptual scheme, or framework, or the basic line of thought, stays the same. So, it’s it and that’s that.

Of course, detailed write-ups, (at least rough) calculations, and some (rough) simulations still have to be worked out, but I am working on them.

I have already written more than 30 pages in the main article (which I should now be converting into a multi-chapter book), and more than 50 pages in the auxiliary material (which I plan to insert in the main text, eventually).

Yes, I have implemented a source control system (SVN), and have been taking regular backups too, though I need to now implement a system of backups to two different external hard-disks.

But all this on-going process of writing will now get interrupted due to my move to the new job, in another city. My blogging too would get interrupted. So, please stay away from this blog for a while. I will try to resume both ASAP, but as of today, can’t tell when—may be a month or so.

(II) To the engineering academics among my readers, esp. the Indian academics:

I have changed my stance regarding publications. All along thus far, I had maintained that I will not publish anything in one of those “new” journals in which most every Indian engineering professor publishes these days.

However, I now realize that one of the points in the approvals (by universities, AICTE, UGC, NAAC, NBA, etc.) concerns journal papers. I have only one journal paper on my CV. Keeping the potential IPR issues in mind, all my other papers were written in only schematic way (the only exception is the diffusion paper), and for that reason, they were published only in the conference proceedings. (I had explicitly discussed this matter not just with my guide, but also with my entire PhD committee.) Of course, I made sure that all these were international conferences, pretty reputed ones, of pretty low acceptance rates (though these days the acceptance rates at these same conferences have gone significantly up (which, incidentally, should be a “good” piece of news to my new students)). But still, as a result, all but one of my papers have been only conference papers, not journal papers.

After suffering through UGC panel interviews at three different colleges (all in SPPU) I now realize that it’s futile to plead your case in front of them. They are insufferable in every sense; they stick to their guns. You can’t beat their sense of “quality,” as it were.

So, I have decided to follow their (I mean my UGC panel interviewers’) lead, and thus have now decided to publish at least three papers in such journals, right over the upcoming couple of months or so.

Forgive me if I report the same old things (which I had reported in those international conferences about a decade ago). I have been assured that conference papers are worthless and that no one reads them. Reporting the same things in journal papers should enhance, I guess, their readability. So, the investigations I report on will be the same, but now they will appear in the Microsoft Word format, and in international journals.

That’s another reason why my blogging will be sparser in the upcoming months.

That way, in the world of science and research, it has always been quite a generally accepted practice, all over the world, to first report your findings in conferences, seek your peers’ opinions on your work or your ideas, and then expand on (or correct on) the material/study, and then send it to journals. There is nothing wrong in it. Even the topmost physicists have followed precisely the same policy. … Why, come to think of it, the very first paper that ushered humanity into the quantum era itself was only a conference talk. In fact it was just a local conference, albeit in an advanced country. I mean Planck’s very first announcement regarding quantization. … So, it’s a perfectly acceptable practice.

The difference this time (I mean, in my, present, case) will be: I will contract on (and hopefully also dumb down) the contents of my conference papers, so as to match the level of the journals in which my UGC panel interviewers themselves publish.

No, the above was not a piece of sarcasm—at least I didn’t mean it, when I wrote it. I merely meant to highlight an objective fact. Given the typical length, font size, gaps in sections, and the overall treatment of the contents of these journals, I will have to both contract on and dumb down on my write-ups. … I will of course also add some new sentences here and there to escape the no-previous-publication clause, but believe me, in my case, that is a very minor worry. The important thing would be to match the level of the treatment, to use the Microsoft Word’s equation editor, and to cut down on the length. Those are my worries.

Another one of my worries is how to publish two journal papers—one good, and one bad—based on the same idea. I mean, suppose I want to publish something on the nature of the $\delta$ of the calculus of variations, in one of these journals. … Incidentally, I do think that what I wrote on this idea right here on this blog a little ago, is worth publishing even in a good journal, say in Am. J. Phys., or at least in the Indian journal “Resonance.” So, I would like to eventually publish it one of these two journals, too. But for immediately enhancing the number of journal papers on my CV, I should immediately publish a shorter version of the same in one of these new international journals too, on an urgent basis. Now the question is: what all aspects I should withhold for now. That is my worry. That’s why, the way my current thinking goes, instead of publishing any new material (say on the $\delta$ of CoV), I should instead simply recycle the already conference-published material.

One final point. Actually, I never did think that it was immoral to publish in such journals (I mean the ones in which my interviewers from SPPU publish). These journals do have ISSN, and they always are indexed in the Google Scholar (which is an acceptable indexing service even to NBA), and sometimes even in Scopus/PubMed etc. Personally, I had refrained from publishing in them not because I thought that it was immoral to do so, but rather because I thought it was plain stupid. I have been treating the invitations from such journals with a sense of humour all along.

But then, the way our system works, it does have the ways and the means to dumb down one and all. Including me. When my very career is at the stake, I will very easily and smoothly go along, toss away my sense of quality and propriety, and join the crowd. (But at least I will be open and forth-right about it—admitting it publicly, the way I have already done, here.)

So, that’s another reason why my blogging would be sparser over the upcoming few months, esp. this month and the next. I will be publishing in (those) journals, on a high priority.

(III) To the QM experts:

Now, a bit to QM experts. By “experts,” I mean those who have studied QM through university courses (or text-books, as in my case) to PG or PhD level. I mean, the QM as it is taught at the UG level, i.e., the non-relativistic version of it.

If you are curious about the exact nature of my ideas, well, you will have to be patient. Months, perhaps even a year, it’s going to take, before I come to write about it on my blog(s). It will take time. I have been engaged in writing about it for about a month by now, and I speak from this experience. And further, the matter of having to immediately publish journal papers in engineering will also interfere the task of writing.

However, if you are an academic in India (say a professor or even just a serious and curious PhD student of physics/chemistry/engg physics program, say at an IIT/IISc/IISER/similar) and are curious to know about my ideas… Well, just give me a call and let’s decide on a mutually convenient time to meet in person. Ditto, for academics/serious students of physics from abroad visiting India.

No, I don’t at all expect any academics in (or visiting) India to be that curious about my work. But still, theoretically speaking, assuming that someone is interested: just send me an email or call me to fix an appointment, and we will discuss my ideas, in person. We will work out at the black-board (better than working on paper, in my experience).

I am not at all hung up about maintaining secrecy until publication. It’s just that writing takes time.

One part of it is that when you write, people also expect a higher level of precision from you, and ensuring that takes time. Making general but precise statements or claims, on a most fundamental topic of physics—it’s QM itself—is difficult, very difficult. Talking to experts is, in contrast, easy—provided you know what you are talking about.

In a direct personal talk, there is a lot of room for going back and forth, jumping around the topics, hand-waving, which is not available in the mode of writing-by-one-then-reading-by-another. And, talking with experts would be easier for me because they already know the context. That’s why I specified PhD physicists/professors at this stage, and not, say, students of engineering or CS folks merely enthusiastic about QM. (Coming to humanity folks, say philosophers, I think that via this work, I have nothing—or next to nothing—to offer to their specialty.)

Personally, I am not comfortable with video-conferencing, though if the person in question is a serious academic or a reputed corporate/national lab researcher, I would sure give it a thought to it. For instance, if some professor from US/UK that I had already interacted with (say at iMechanica, or at his blog, or via emails) wants to now know about my new ideas and wants a discussion via Skype, I could perhaps go in for it—even though I would not be quite comfortable with the video-conferencing mode as such. The direct, in person talk, working together at the black-board, works best for me. I don’t find Skype comfortable enough even with my own class-mates or close personal relations. It just doesn’t work by me. So, try to keep it out.

For the same reason—the planning and the precision required in writing—I would mostly not be able to even blog about my new ideas. Interactions on blogs tends to introduce too many bifurcations in the discussion, and therefore, even though the different PoV could be valuable, such interactions should be introduced only after the first cut in the writing is already over. That’s why, the most I would be able to manage on this blog would be some isolated aspects—granted that some inconsistencies or contradictions could still easily slip in. I am not sure, but I will try to cover at least some isolated aspects from time to time.

Here’s an instance. (Let me remind you: I am addressing this part to those who have already studied QM through text-books, esp. to PhD physicists. I am not only referring to equations, but more importantly, I am assuming the context of a direct knowledge of how topics like the one below are generally treated in various books and references.)

Did you ever notice just how radical was de Broglie’s idea? I mean, for the electron, the equations de Broglie used were:

$E = \hbar \nu$ and $p = \hbar k$.

Routine stuff, do you say? But notice, in the special relativity, i.e. in the classical electrodynamics, the equation for the energy of a massive particle is:
$E^2 = (pc)^2 + (m_0 c^2)^2$

In arriving at the relation $p = \hbar k$, Einstein had dropped the second term ($m_0^2 c^4$) from the expression for energy because radiation has no mass, and so, his hypothetical particles also would carry no mass.

When de Broglie assumed that this same expression holds also for the electron—its matter waves—what he basically was doing was: to take an expression derived for a massless particle (Einstein’s quantum of light) as is, and to assume that it would apply also for the massive particle (i.e. the electron).

In effect, what de Broglie had ended up asserting was that the matter-waves of the electron had a massless nature.

Got it? See how radical—and how subtly (indirectly, implicitly) slipped in—is that suggestion? Have you seen this aspect highlighted or discussed this way in a good university course or a text-book on modern physics or QM? …

…QM is subtle, very subtle. That’s why working out a conceptually consistent scheme for it is (and has been) such a fun.

The above observation was one of my clues in working out my new scheme. The other was the presence of the classical features in QM. Not only the pop-science books but also text-books on modern physics (and QM) had led me to believe that what the QM represented was completely radical break from the classical physic. Uh-oh. Not quite.

Radical ideas, QM does have. But completely radical? Not quite.

QM, actually, is hybrid. It does have a lot of classical elements built into it, right in its postulates. I had come to notice this part and was uncomfortable with it—I didn’t have the confidence in my own observation; I used to think that when I study more of QM, I would be shown how these classical features fall away. That part never happened, not even as my further studies of QM progressed, and so, I slowly became more confident about it. QM is hybrid, full stop. It does have classical features built right in its postulates, even in its maths. It does not represent a complete break from the classical physics—not as complete a break as physicists lead you to believe. That was my major clue.

Other clues came as my grasp of the nature of the QM maths became better and firmer, which occurred over a period of time. I mean the nature of the maths of: the Fourier theory, the variational calculus, the operator theory, and the higher-dimensional spaces.

I had come to understand the Fourier theory via my research on diffusion, and the variational calculus, via my studies (and teaching!) of FEM. The operator theory, I had come to suspect (simply comparing the way people used to write in the early days of QM, and the way they now write) was not essential to the physics of the QM theory. So I had begun mentally substituting the operators acting on the wavefunction by just a modified wavefunction itself. … Hell, do you express a classical problem—say a Poisson equation problem or a Navier-Stokes problem—via operators? These days people do, but, thankfully, the trend has not yet made it to the UG text-books to a significant extent. The whole idea of the operator theory is irrelevant to physics—its only use and relevance is in maths. … Soon enough, I then realized that the wavefunction itself is a curious construct. It’s pointless debating whether the wavefunction is ontic or epistemic, primarily because the damn thing is dimensionless. Physicists always take care to highlight the fact that its evolution is unitary, but what they never tell you, never ever highlight, is the fact that the damn thing has no dimensions. Qua a dimensionless quantity, it is merely a way of organizing some other quantities that do have a physical existence. As to its unitary evolution, well, all that this idea says is that it is merely a weighting function, so to speak. But it was while teaching thermodynamics (in Mumbai in 2014 and in Pune in 2015) that I finally connected the variational principles with the operator theory, the thermodynamic system with the quantum system, and this way then got my breakthroughs (or at least my clues).

Yet another clue was the appreciation of the fact that the world is remarkably stable. When you throw a ball, it goes through the space as a single object. The part of the huge Hilbert space of the entire universe which represents the ball—all the quantum particles in it—somehow does not come to occupy a bigger part of that space. Their relations to each other somehow stay stable. That was another clue.

As to the higher-dimensional function spaces, again, my climb was slow but steady. I had begun writing my series of posts on the idea of space. It helped. Then I worked through higher-dimensional space. A rough-and-ready version of my understanding was done right on this blog. It was then that my inchoate suspicions about the nature of the Hilbert space finally began to fall in place. There is an entrenched view, viz., that the wavefunction is a “vector” that “lives” only in a higher-dimensional abstract space, and that the existence of the tensor product over the higher-dimensional space makes it in principle impossible to visualize the wavefunction for a multi-particle quantum system, which means, any quantum system which is more complex than the hydrogen atom (i.e. a single electron). Schrodinger didn’t introduce this idea, but when Lorentz pointed out that a higher-dimensional space was implied by Schrodinger’s procedure, Schrodinger first felt frustrated, and later on, in any case, he was unable to overcome this objection. And so, this part got entrenched—and became a part of the mathematicians’ myths of QM. As my own grasp of this part of the maths became better (and it was engineers’ writings on linear algebra that helped me improve my grasp, not physicists’ or mathematicians’ (which I did attempt valiantly, and which didn’t help at all)) I got my further clues. For a clue, see my post on the CoV; I do mention, first, the Cartesian product, and then, a tensor product, in it.

Another clue was a better understanding of the nonlinear vs. linear distinction in maths. It too happened slowly.

As to others’ writings, the most helpful clue came from the “anti-photon” paper by (the Nobel laureate) W. E. Lamb. Among the bloggers, I found some of the write-ups by Lubos Motl to be really helpful; also a few by Schlafly. Discussions on Scott Aaronson’s blog were useful to check out the different perspectives on the quantum problems.

The most stubborn problem for me perhaps was the measurement problem, i.e. the collapse postulate. But to say anything more about it right away would be premature—it would too premature, in fact. I want to do it right—even though I will surely follow the adage that a completed document is better than a perfect document. Perfection may get achieved only on collapse, but I happily don’t carry the notion that a good treatment on the collapse postulate has to be preceded by a collapse.

Though the conceptual framework I now have in mind is new, once it is published, it would not be found, I think, to be very radically new—not by the working physicists or the QM experts themselves anyway. …

.. I mean, personally speaking, when I for the first time thought of this new way of thinking about the QM maths, it was radically new (and radically clarifying) to me. (As I said, it happened slowly, over a period of time, starting, may be, from second half of 2015 or so if not earlier).

But since then, through my regular searches on the ‘net, I have found that other people have been suggesting somewhat similar ideas for quite some time, though they have been, IMO, not as fully consistent as they could have been. For example, see Philip Wallace[^]’s work (which I came across only recently, right this month). Or, see Martin Ligare[^]’s papers (which I ran into just last month, on the evening of 25th January, to be precise). … Very close to my ideas, but not quite the same. And, not as conceptually comprehensive, if that’s the right word to use for it.

My tentative plan as of now is to first finish writing the document (already 30+ pages, as I mentioned above in the first section). This document is in the nature of a conceptual road-map, or a position/research-program paper. Call it a white-paper sort of a document, say. I want to finish it first. Simultaneously, I will also try to do some simulations or so, and only then go for writing papers for (good) journals. … Sharing of ideas on this blog wouldn’t have to wait until the papers though; it could begin much earlier than that, in fact as soon as the position paper is done, which should be after a few months—say by June-July at the earliest. I will try to keep this position paper as brief as possible, say under 100 pages.

Let’s see how it all goes. I will keep you updated. But yes, the goals are clear now.

I wrote this lengthy a post (almost 5000 words) because I did want to get all these things from my mind and on to the blog. But since in the immediate future I would be busy in organizing for the move (right from hunting for a house/flat to rent, to deciding on what all stuff to leave in Pune for the time being and what all to take with me), to the actual move (the actual packing, moving, and unpacking etc.), I wouldn’t get the time to blog over the next 2–3 weeks, may be until it’s March already. Realizing it, I decided to just gather all this material, which is worth 3 posts, and to dump it all together in this single post. So, there.

Bye for now.

[As usual, a minor revision or two may be done later.]

/

# What am I thinking about? …and what should it be?

What am I thinking about?

It’s the “derivation” of the Schrodinger equation. Here’s how a simplest presentation of it goes:

The kinetic energy $T$ of a massive particle is given, in classical mechanics, as
$T = \dfrac{1}{2}mv^2 = \dfrac{p^2}{2m}$
where $v$ is the velocity, $m$ is the mass, and $p$ is the momentum. (We deal with only the scalar magnitudes, in this rough-and-ready “analysis.”)

If the motion of the particle occurs additionally also under the influence of a potential field $V$, then its total energy $E$ is given by:
$E = T + V = \dfrac{p^2}{2m} + V$

In classical electrodynamics, it can be shown that for a light wave, the following relation holds:
$E = pc$
where $E$ is the energy of light, $p$ is its momentum, and $c$ is its speed. Further, for light in vacuum:
$\omega = ck$
where $k = \frac{2\pi}{\lambda}$ is the wavevector.

Planck hypothesized that in the problem of the cavity radiation, the energy-levels of the electromagnetic oscillators in the metallic cavity walls maintained at thermal equilibrium are quantized, somehow:
$E = h \nu = \hbar \omega$
where $\hbar = \frac{h}{2\pi}$  and $\omega = 2 \pi \nu$ is the angular frequency. Making this vital hypothesis, he could successfully predict the power spectrum of the cavity radiation (getting rid of the ultraviolet catastrophe).

In explaining the photoelectric effect, Einstein hypothesized that lights consists of massless particles. He took Planck’s relation $E = \hbar \omega$ as is, and then, substituted on its left hand-side the classical expression for the energy of the radiation $E = pc$. On the right hand-side he substituted the relation which holds for light in vacuum, viz. $\omega = c k$. He thus arrived at the expression for the quantized momentum for the hypothetical particles of light:
$p = \hbar k$
With the hypothesis of the quanta of light, he successfully explained all the known experimentally determined features of the photoelectric effect.

Whereas Planck had quantized the equilibrium energy of the charged oscillators in the metallic cavity wall, Einstein quantized the electromagnetic radiation within the cavity itself, via spatially discrete particles of light—an assumption that remains questionable till this day (see “Anti-photon”).

Bohr hypothesized a planetary model of the atom. It had negatively charged and massive point particles of electrons orbiting around the positively charged and massive, point-particles of the nucleus. The model carried a physically unexplained feature of the stationary of the electronic orbits—i.e. the orbits travelling in which an electron, somehow, does not emit/absorb any radiation, in contradiction to the classical electrodynamics. However, this way, Bohr could successfully predict the hydrogen atom spectra. (Later, Sommerfeld made some minor corrections to Bohr’s model.)

de Broglie hypothesized that the relations $E = \hbar \omega$ and $p = \hbar k$ hold not only just for the massless particles of light as proposed by Einstein, but, by analogy, also for the massive particles like electrons. Since light had both wave and particle characters, so must, by analogy, the electrons. He hypothesized that the stationarity of the Bohr orbits (and the quantization of the angular momentum for the Bohr electron) may be explained by assuming that matter waves associated with the electrons somehow form a standing-wave pattern for the stationary orbits.

Schrodinger assumed that de Broglie’s hypothesis for massive particles holds true. He generalized de Broglie’s model by recasting the problem from that of the standing waves in the (more or less planar) Bohr orbits, to an eigenvalue problem of a differential equation over the entirety of space.

The scheme of  the “derivation” of Schrodinger’s differential equation is “simple” enough. First assuming that the electron is a complex-valued wave, we work out the expressions for its partial differentiations in space and time. Then, assuming that the electron is a particle, we invoke the classical expression for the total energy of a classical massive particle, for it. Finally, we mathematically relate the two—somehow.

Assume that the electron’s state is given by a complex-valued wavefunction having the complex-exponential form:
$\Psi(x,t) = A e^{i(kx -\omega t)}$

Partially differentiating twice w.r.t. space, we get:
$\dfrac{\partial^2 \Psi}{\partial x^2} = -k^2 \Psi$
Partially differentiating once w.r.t. time, we get:
$\dfrac{\partial \Psi}{\partial t} = -i \omega \Psi$

Assume a time-independent potential. Then, the classical expression for the total energy of a massive particle like the electron is:
$E = T + V = \dfrac{p^2}{2m} + V$
Note, this is not a statement of conservation of energy. It is merely a statement that the total energy has two and only two components: kinetic energy, and potential energy.

Now in this—classical—equation for the total energy of a massive particle of matter, we substitute the de Broglie relations for the matter-wave, viz. the relations $E = \hbar \omega$ and $p = \hbar k$. We thus obtain:
$\hbar \omega = \dfrac{\hbar^2 k^2}{2m} + V$
which is the new, hybrid form of the equation for the total energy. (It’s hybrid, because we have used de Broglie’s matter-wave postulates in a classical expression for the energy of a classical particle.)

Multiply both sides by $\Psi(x,t)$ to get:
$\hbar \omega \Psi(x,t) = \dfrac{\hbar^2 k^2}{2m}\Psi(x,t) + V(x)\Psi(x,t)$

Now using the implications for $\Psi$ obtained via its partial differentiations, namely:
$k^2 \Psi = - \dfrac{\partial^2 \Psi}{\partial x^2}$
and
$\omega \Psi = i \dfrac{\partial \Psi}{\partial t}$
and substituting them into the hybrid equation for the total energy, we get:
$i \hbar \dfrac{\partial \Psi(x,t)}{\partial t} = - \dfrac{\hbar^2}{2m}\dfrac{\partial^2\Psi(x,t)}{\partial x^2} + V(x)\Psi(x,t)$

That’s what the time-dependent Schrodinger equation is.

And that—the “derivation” of the Schrodinger equation thus presented—is what I have been thinking of.

Apart from the peculiar mixture of the wave and particle paradigms followed in this “derivation,” the other few points, to my naive mind, seem to be: (i) the use of a complex-valued wavefunction, (ii) the step of multiplying the hybrid equation for the total energy, by this wavefunction, and (iii) the step of replacing $\omega \Psi(x,t)$ by $i \dfrac{\partial \Psi}{\partial t}$, and also replacing $k^2 \Psi$ by $- \dfrac{\partial^2 \Psi}{\partial x^2}$. Pretty rare, that step seems like, doesn’t it? I mean to say, just because it is multiplied by a variable, you are replacing a good and honest field variable by a partial time-derivative (or a partial space-derivative) of that same field variable! Pretty rare, a step like that is, in physics or engineering, don’t you think? Do you remember any other place in physics or engineering where we do something like that?

What should I think about?

Is there is any mechanical engineering topic that you want me to explain to you?

If so, send me your suggestions. If I find them suitable, I will begin thinking about them. May be, I will even answer them for you, here on this blog.

If not…

If not, there is always this one, involving the calculus of variations, again!:

Derbes, David (1996) “Feynman’s derivation of the Schrodinger equation,” Am. J. Phys., vol. 64, no. 7, July 1996, pp. 881–884

I’ve already found that I don’t agree with how Derbes uses the term “local”, in this article. His article makes it seem as if the local is nothing but a smallish segment on what essentially is a globally determined path. I don’t agree with that implication. …

However, here, although this issue is of relevance to the mechanical engineering proper, in the absence of a proper job (an Officially Approved Full Professor in Mechanical Engineering’s job), I don’t feel motivated to explain myself.

Instead, I find the following article by a Mechanical Engineering professor interesting: [^]

And, oh, BTW, if you are a blind follower of Feynman’s, do check out this one:

Briggs, John S. and Rost, Jan M. (2001) “On the derivation of the time-dependent equation of Schrodinger,” Foundations of Physics, vol. 31, no. 4, pp. 693–712.

I was delighted to find a mention of a system and an environment (so close to the heart of an engineer), even in this article on physics. (I have not yet finished reading it. But, yes, it too invokes the variational principles.)

OK then, bye for now.

[As usual, may be I will come back tomorrow and correct the write-up or streamline it a bit, though not a lot. Done on 2017.01.19.]

[E&OE]

# See, how hard I am trying to become an Approved (Full) Professor of Mechanical Engineering in SPPU?—4

In this post, I provide my answer to the question which I had raised last time, viz., about the differences between the $\Delta$, the $\text{d}$, and the $\delta$ (the first two, of the usual calculus, and the last one, of the calculus of variations).

Some pre-requisite ideas:

A system is some physical object chosen (or isolated) for study. For continua, it is convenient to select a region of space for study, in which case that region of space (holding some physical continuum) may also be regarded as a system. The system boundary is an abstraction.

A state of a system denotes a physically unique and reproducible condition of that system. State properties are the properties or attributes that together uniquely and fully characterize a state of a system, for the chosen purposes. The state is an axiom, and state properties are its corollary.

State properties for continua are typically expressed as functions of space and time. For instance, pressure, temperature, volume, energy, etc. of a fluid are all state properties. Since state properties uniquely define the condition of a system, they represent definite points in an appropriate, abstract, (possibly) higher-dimensional state space. For this reason, state properties are also called point functions.

A process (synonymous to system evolution) is a succession of states. In classical physics, the succession (or progression) is taken to be continuous. In quantum mechanics, there is no notion of a process; see later in this post.

A process is often represented as a path in a state space that connects the two end-points of the staring and ending states. A parametric function defined over the length of a path is called a path function.

A cyclic process is one that has the same start and end points.

During a cyclic process, a state function returns to its initial value. However, a path function does not necessarily return to the same value over every cyclic change—it depends on which particular path is chosen. For instance, if you take a round trip from point $A$ to point $B$ and back, you may spend some amount of money $m$ if you take one route but another amount $n$ if you take another route. In both cases you do return to the same point viz. $A$, but the amount you spend is different for each route. Your position is a state function, and the amount you spend is a path function.

[I may make the above description a bit more rigorous later on (by consulting a certain book which I don’t have handy right away (and my notes of last year are gone in the HDD crash)).]

The $\Delta$, the $\text{d}$, and the $\delta$:

The $\Delta$ denotes a sufficiently small but finite, and locally existing difference in different parts of a system. Typically, since state properties are defined as (continuous) functions of space and time, what the $\Delta$ represents is a finite change in some state property function that exists across two different but adjacent points in space (or two nearby instants in times), for a given system.

The $\Delta$ is a local quantity, because it is defined and evaluated around a specific point of space and/or time. In other words, an instance of $\Delta$ is evaluated at a fixed $x$ or $t$. The $\Delta x$ simply denotes a change of position; it may or may not mean a displacement.

The $\text{d}$ (i.e. the infinitesimal) is nothing but the $\Delta$ taken in some appropriate limiting process to the vanishingly small limit.

Since $\Delta$ is locally defined, so is the infinitesimal (i.e. $\text{d}$).

The $\delta$ of CoV is completely different from the above two concepts.

The $\delta$ is a sufficiently small but global difference between the states (or paths) of two different, abstract, but otherwise identical views of the same physically existing system.

Considering the fact that an abstract view of a system is itself a system, $\delta$ also may be regarded as a difference between two systems.

Though differences in paths are not only possible but also routinely used in CoV, in this post, to keep matters simple, we will mostly consider differences in the states of the two systems.

In CoV, the two states (of the two systems) are so chosen as to satisfy the same Dirichlet (i.e. field) boundary conditions separately in each system.

The state function may be defined over an abstract space. In this post, we shall not pursue this line of thought. Thus, the state function will always be a function of the physical, ambient space (defined in reference to the extensions and locations of concretely existing physical objects).

Since a state of a system of nonzero size can only be defined by specifying its values for all parts of a system (of which it is a state), a difference between states (of the two systems involved in the variation $\delta$) is necessarily global.

In defining $\delta$, both the systems are considered only abstractly; it is presumed that at most one of them may correspond to an actual state of a physical system (i.e. a system existing in the physical reality).

The idea of a process, i.e. the very idea of a system evolution, necessarily applies only to a single system.

What the $\delta$ represents is not an evolution because it does not represent a change in a system, in the first place. The variation, to repeat, represents a difference between two systems satisfying the same field boundary conditions. Hence, there is no evolution to speak of. When compressed air is passed into a rubber balloon, its size increases. This change occurs over certain time, and is an instance of an evolution. However, two rubber balloons already inflated to different sizes share no evolutionary relation with each other; there is no common physical process connecting the two; hence no change occurring over time can possibly enter their comparative description.

Thus, the “change” denoted by $\delta$ is incapable of representing a process or a system evolution. In fact, the word “change” itself is something of a misnomer here.

Text-books often stupidly try to capture the aforementioned idea by saying that $\delta$ represents a small and possibly finite change that occurs without any elapse of time. Apart from the mind-numbing idea of a finite change occurring over no time (or equally stupefying ideas which it suggests, viz., a change existing at literally the same instant of time, or, alternatively, a process of change that somehow occurs to a given system but “outside” of any time), what they, in a way, continue to suggest also is the erroneous idea that we are working with only a single, concretely physical system, here.

But that is not the idea behind $\delta$ at all.

To complicate the matters further, no separate symbol is used when the variation $\delta$ is made vanishingly small.

In the primary sense of the term variation (or $\delta$), the difference it represents is finite in nature. The variation is basically a function of space (and time), and at every value of $x$ (and $t$), the value of $\delta$ is finite, in the primary sense of the word. Yes, these values can be made vanishingly small, though the idea of the limits applied in this context is different. (Hint: Expand each of the two state functions in a power series and relate each of the corresponding power terms via a separate parameter. Then, put the difference in each parameter through a limiting process to vanish. You may also use the Fourier expansion.))

The difference represented by $\delta$ is between two abstract views of a system. The two systems are related only in an abstract view, i.e., only in (the mathematical) thought. In the CoV, they are supposed as connected, but the connection between them is not concretely physical because there are no two separate physical systems concretely existing, in the first place. Both the systems here are mathematical abstractions—they first have been abstracted away from the real, physical system actually existing out there (of which there is only a single instance).

But, yes, there is a sense in which we can say that $\delta$ does have a physical meaning: it carries the same physical units as for the state functions of the two abstract systems.

An example from biology:

Here is an example of the differences between two different paths (rather than two different states).

Plot the height $h(t)$ of a growing sapling at different times, and connect the dots to yield a continuous graph of the height as a function of time. The difference in the heights of the sapling at two different instants is $\Delta h$. But if you consider two different saplings planted at the same time, and assuming that they grow to the same final height at the end of some definite time period (just pick some moment where their graphs cross each other), and then, abstractly regarding them as some sort of imaginary plants, if you plot the difference between the two graphs, that is the variation or $\delta h(t)$ in the height-function of either. The variation itself is a function (here of time); it has the units, of course, of m.

Summary:

The $\Delta$ is a local change inside a single system, and $\text{d}$ is its limiting value, whereas the $\delta$ is a difference across two abstract systems differing in their global states (or global paths), and there is no separate symbol to capture this object in the vanishingly small limit.

Exercises:

Consider one period of the function $y = A \sin(x)$, say over the interval $[0,2\pi]$; $A = a$ is a small, real-valued, constant. Now, set $A = 1.1a$. Is the change/difference here a $\delta$ or a $\Delta$? Why or why not?

Now, take the derivative, i.e., $y' = A \cos(x)$, with $A = a$ once again. Is the change/difference here a $\delta$ or a $\Delta$? Why or why not?

Which one of the above two is a bigger change/difference?

Also consider this angle: Taking the derivative did affect the whole function. If so, why is it that we said that $\text{d}$ was necessarily a local change?

An important and special note:

The above exercises, I am sure, many (though not all) of the Officially Approved Full Professors of Mechanical Engineering at the Savitribai Phule Pune University and COEP would be able to do correctly. But the question I posed last time was: Would it be therefore possible for them to spell out the physical meaning of the variation i.e. $\delta$? I continue to think not. And, importantly, even among those who do solve the above exercises successfully, they wouldn’t be too sure about their own answers. Upon just a little deeper probing, they would just throw up their hands. [Ditto, for many American physicists.] Even if a conceptual clarity is required in applications.

(I am ever willing and ready to change my mind about it, but doing so would need some actual evidence—just the way my (continuing) position had been derived, in the first place, from actual observations of them.)

The reason I made this special note was because I continue to go jobless, and nearly bank balance-less (and also, nearly cashless). And it all is basically because of folks like these (and the Indians like the SPPU authorities). It is their fault. (And, no, you can’t try to lift what is properly their moral responsibility off their shoulders and then, in fact, go even further, and attempt to place it on mine. Don’t attempt doing that.)

A Song I Like:

[May be I have run this song before. If yes, I will replace it with some other song tomorrow or so. No I had not.]

Hindi: “Thandi hawaa, yeh chaandani suhaani…”
Music and Singer: Kishore Kumar
Lyrics: Majrooh Sultanpuri

[A quick ‘net search on plagiarism tells me that the tune of this song was lifted from Julius La Rosa’s 1955 song “Domani.” I heard that song for the first time only today. I think that the lyrics of the Hindi song are better. As to renditions, I like Kishor Kumar’s version better.]

[Minor editing may be done later on and the typos may be corrected, but the essentials of my positions won’t be. Mostly done right today, i.e., on 06th January, 2017.]

[E&OE]

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# See, how hard I am trying to become an Approved (Full) Professor of Mechanical Engineering in SPPU?—3

I was looking for a certain book on heat transfer which I had (as usual) misplaced somewhere, and while searching for that book at home, I accidentally ran into another book I had—the one on Classical Mechanics by Rana and Joag [^].

After dusting this book a bit, I spent some time in one typical way, viz. by going over some fond memories associated with a suddenly re-found book…. The memories of how enthusiastic I once was when I had bought that book; how I had decided to finish that book right within weeks of buying it several years ago; the number of times I might have picked it up, and soon later on, kept it back aside somewhere, etc.  …

Yes, that’s right. I have not yet managed to finish this book. Why, I have not even managed to begin reading this book the way it should be read—with a paper and pencil at hand to work through the equations and the problems. That was the reason why, I now felt a bit guilty. … It just so happened that it was just the other day (or so) when I was happily mentioning the Poisson brackets on Prof. Scott Aaronson’s blog, at this thread [^]. … To remove (at least some part of) my sense of guilt, I then decided to browse at least through this part (viz., Poisson’s brackets) in this book. … Then, reading a little through this chapter, I decided to browse through the preceding chapters from the Lagrangian mechanics on which it depends, and then, in general, also on the calculus of variations.

It was at this point that I suddenly happened to remember the reason why I had never been able to finish (even the portions relevant to engineering from) this book.

The thing was, the explanation of the $\delta$—the delta of the variational calculus.

The explanation of what the $\delta$ basically means, I had found right back then (many, many years ago), was not satisfactorily given in this book. The book did talk of all those things like the holonomic constraints vs. the nonholonomic constraints, the functionals, integration by parts, etc. etc. etc. But without ever really telling me, in a forth-right and explicit manner, what the hell this $\delta$ was basically supposed to mean! How this $\delta y$ was different from the finite changes ($\Delta y$) and the infinitesimal changes ($\text{d}y$) of the usual calculus, for instance. In terms of its physical meaning, that is. (Hell, this book was supposed to be on physics, wasn’t it?)

Here, I of course fully realize that describing Rana and Joag’s book as “unsatisfactory” is making a rather bold statement, a very courageous one, in fact. This book is extraordinarily well-written. And yet, there I was, many, many years ago, trying to understand the delta, and not getting anywhere, not even with this book in my hand. (OK, a confession. The current copy which I have is not all that old. My old copy is gone by now (i.e., permanently misplaced or so), and so, the current copy is the one which I had bought once again, in 2009. As to my old copy, I think, I had bought it sometime in the mid-1990s.)

It was many years later, guess some time while teaching FEM to the undergraduates in Mumbai, that the concept had finally become clear enough to me. Most especially, while I was going through P. Seshu’s and J. N. Reddy’s books. [Reflected Glory Alert! Professor P. Seshu was my class-mate for a few courses at IIT Madras!] However, even then, even at that time, I remember, I still had this odd feeling that the physical meaning was still not clear to me—not as as clear as it should be. The matter eventually became “fully” clear to me only later on, while musing about the differences between the perspective of Thermodynamics on the one hand and that of Heat Transfer on the other. That was some time last year, while teaching Thermodynamics to the PG students here in Pune.

Thermodynamics deals with systems at equilibria, primarily. Yes, its methods can be extended to handle also the non-equilibrium situations. However, even then, the basis of the approach summarily lies only in the equilibrium states. Heat Transfer, on the other hand, necessarily deals with the non-equilibrium situations. Remove the temperature gradient, and there is no more heat left to speak of. There does remain the thermal energy (as a form of the internal energy), but not heat. (Remember, heat is the thermal energy in transit that appears on a system boundary.) Heat transfer necessarily requires an absence of thermal equilibrium. … Anyway, it was while teaching thermodynamics last year, and only incidentally pondering about its differences from heat transfer, that the idea of the variations (of Cov) had finally become (conceptually) clear to me. (No, CoV does not necessarily deal only with the equilibrium states; it’s just that it was while thinking about the equilibrium vs. the transient that the matter about CoV had suddenly “clicked” to me.)

In this post, let me now note down something on the concept of the variation, i.e., towards understanding the physical meaning of the symbol $\delta$.

Please note, I have made an inline update on 26th December 2016. It makes the presentation of the calculus of variations a bit less dumbed down. The updated portion is clearly marked as such, in the text.

The Problem Description:

The concept of variations is abstract. We would be better off considering a simple, concrete, physical situation first, and only then try to understand the meaning of this abstract concept.

Accordingly, consider a certain idealized system. See its schematic diagram below:

There is a long, rigid cylinder made from some transparent material like glass. The left hand-side end of the cylinder is hermetically sealed with a rigid seal. At the other end of the cylinder, there is a friction-less piston which can be driven by some external means.

Further, there also are a couple of thin, circular, piston-like disks ($D_1$ and $D_2$) placed inside the cylinder, at some $x_1$ and $x_2$ positions along its length. These disks thus divide the cylindrical cavity into three distinct compartments. The disks are assumed to be impermeable, and fitting snugly, they in general permit no movement of gas across their plane. However, they also are assumed to be able to move without any friction.

Initially, all the three compartments are filled with a compressible fluid to the same pressure in each compartment, say 1 atm. Since all the three compartments are at the same pressure, the disks stay stationary.

Then, suppose that the piston on the extreme right end is moved, say from position $P_1$ to $P_2$. The final position $P_2$ may be to the left or to the right of the initial position $P_1$; it doesn’t matter. For the current description, however, let’s suppose that the position $P_2$ is to the left of $P_1$. The effect of the piston movement thus is to increase the pressure inside the system.

The problem is to determine the nature of the resulting displacements that the two disks undergo as measured from their respective initial positions.

There are essentially two entirely different paradigms for conducting an analysis of this problem.

The “Vector Mechanics” Paradigm:

The first paradigm is based on an approach that was put to use so successfully by Newton. Usually, it is called the paradigm of vector analysis.

In this paradigm, we focus on the fact that the forced displacement of the piston with time, $x(t)$, may be described using some function of time that is defined over the interval lying between two instants $t_i$ and $t_f$.

For example, suppose the function is:
$x(t) = x_0 + v t$,
where $v$ is a constant. In other words, the motion of the piston is steady, with a constant velocity, between the initial and final instants. Since the velocity is constant, there is no acceleration over the open interval $(t_i, t_f)$.

However, notice that before the instant $t_i$, the piston velocity was zero. Then, the velocity suddenly became a finite (constant) value. Therefore, if you extend the interval to include the end-instants as well, i.e., if you consider the semi-closed interval $[t_i, t_f)$, then there is an acceleration at the instant $t_i$. Similarly, since the piston comes to a position of rest at $t = t_f$, there also is another acceleration, equal in magnitude and opposite in direction, which appears at the instant $t_f$.

The existence of these two instantaneous accelerations implies that jerks or pressure waves are sent through the system. We may model them as vector quantities, as impulses. [Side Exercise: Work out what happens if we consider only the open interval $(t_i, t_f)$.]

We can now apply Newton’s 3 laws, based on the idea that shock-waves must have begun at the piston at the instant $t = t_i$. They must have got transmitted through the gas kept under pressure, and they must have affected the disk $D_1$ lying closest to the piston, thereby setting this disk into motion. This motion must have passed through the gas in the middle compartment of the system as another pulse in the pressure (generated at the disk $D_1$), thereby setting also the disk $D_2$ in a state of motion a little while later. Finally, the pulse must have got bounced off the seal on the left hand side, and in turn, come back to affect the motion of the disk $D_2$, and then of the disk $D_1$. Continuing their travels to and fro, the pulses, and hence the disks, would thus be put in a back and forth motion.

After a while, these transients would move forth and back, superpose, and some of their constituent frequencies would get cancelled out, leaving only those frequencies operative such that the three compartments are put under some kind of stationary states.

In case the gas is not ideal, there would be damping anyway, and after a sufficiently long while, the disks would move through such small displacements that we could easily ignore the ever-decreasing displacements in a limiting argument.

Thus, assume that, after an elapse of a sufficiently long time, the disks become stationary. Of course, their new positions are not the same as their original positions.

The problem thus can be modeled as basically a transient one. The state of the new equilibrium state is thus primarily seen as an effect or an end-result of a couple of transient processes which occur in the forward and backward directions. The equilibrium is seen as not a primarily existing state, but as a result of two equal and opposite transient causes.

Notice that throughout this process, Newton’s laws can be applied directly. The nature of the analysis is such that the quantities in question—viz. the displacements of the disks—always are real, i.e., they correspond to what actually is supposed to exist in the reality out there.

The (values of) displacements are real in the sense that the mathematical analysis procedure itself involves only those (values of) displacements which can actually occur in reality. The analysis does not concern itself with some other displacements that might have been possible but don’t actually occur. The analysis begins with the forced displacement condition, translates it into pressure waves, which in turn are used in order to derive the predicted displacements in the gas in the system, at each instant. Thus, at any arbitrary instant of time $t > t_i$ (in fact, the analysis here runs for times $t \gg t_f$), the analysis remains concerned only with those displacements that are actually taking place at that instant.

The Method of Calculus of Variations:

The second paradigm follows the energetics program. This program was initiated by Newton himself as well as by Leibnitz. However, it was pursued vigorously not by Newton but rather by Leibnitz, and then by a series of gifted mathematicians-physicists: the Bernoulli brothers, Euler, Lagrange, Hamilton, and others. This paradigm is essentially based on the calculus of variations. The idea here is something like the following.

We do not care for a local description at all. Thus, we do not analyze the situation in terms of the local pressure pulses, their momenta/forces, etc. All that we focus on are just two sets of quantities: the initial positions of the disks, and their final positions.

For instance, focus on the disk $D_1$. It initially is at the position $x_{1_i}$. It is found, after a long elapse of time (i.e., at the next equilibrium state), to have moved to $x_{1_f}$. The question is: how to relate this change in $x_1$ on the one hand, to the displacement that the piston itself undergoes from $P_{x_i}$ to $P_{x_f}$.

To analyze this question, the energetics program (i.e., the calculus of variations) adopts a seemingly strange methodology.

It begins by saying that there is nothing unique to the specific value of the position $x_{1_f}$ as assumed by the disk $D_1$. The disk could have come to a halt at any other (nearby) position, e.g., at some other point $x_{1_1}$, or $x_{1_2}$, or $x_{1_3}$, … etc. In fact, since there are an infinity of points lying in a finite segment of line, there could have been an infinity of positions where the disk could have come to a rest, when the new equilibrium was reached.

Of course, in reality, the disk $D_1$ comes to a halt at none of these other positions; it comes to a halt only at $x_{1_f}$.

Yet, the theory says, we need to be “all-inclusive,” in a way. We need not, just for the aforementioned reason, deny a place in our analysis to these other positions. The analysis must include all such possible positions—even if they be purely hypothetical, imaginary, or unreal. What we do in the analysis, this paradigm says, is to initially include these merely hypothetical, unrealistic positions too on exactly the same footing as that enjoyed by that one position which is realistic, which is given by $x_{1_f}$.

Thus, we take a set of all possible positions for each disk. Then, for each such a position, we calculate the “impact” it would make on the energy of the system taken as a whole.

The energy of the system can be additively decomposed into the energies carried by each of its sub-parts. Thus, focusing on disk $D_1$, for each one of its possible (hypothetical) final position, we should calculate the energies carried by both its adjacent compartments. Since a change in $D_1$‘s position does not affect the compartment 3, we need not include it. However, for the disk $D_1$, we do need to include the energies carried by both the compartments 1 and 2. Similarly, for each of the possible positions occupied by the disk $D_2$, it should include the energies of the compartments 2 and 3, but not of 1.

At this point, to bring simplicity (and thereby better) clarity to this entire procedure, let us further assume that the possible positions of each disk forms a finite set. For instance, each disk can occupy only one of the positions that is some $-5, -4, -3, -2, -1, 0, +1, +2, +3, +4$ or $+5$ distance-units away from its initial position. Thus, a disk is not allowed to come to a rest at, say, $2.3$ units; it must do so either at $2$ or at $3$ units. (We will thus perform the initial analysis in terms of only the integer positions, and only later on extend it to any real-valued positions.) (If you are a mechanical engineering student, suggest a suitable mechanism that can ensure only integer relative displacements.)

The change in energy $E$ of a compartment is given by
$\Delta E = P A \Delta x$,
where $P$ is the pressure, $A$ is the cross-sectional area of the cylinder, and $\Delta x$ is the change in the length of the compartment.

Now, observe that the energy of the middle compartment depends on the relative distance between the two disks lying on its sides. Yet, for the same reason, the energy of the middle compartment does depend on both these positions. Hence, we must take a Cartesian product of the relative displacements undergone by both the disks, and only then calculate the system energy for each such a permutation (i.e. the ordered pair) of their positions. Let us go over the details of the Cartesian product.

The Cartesian product of the two positions may be stated as a row-by-row listing of ordered pairs of the relative positions of $D_1$ and $D_2$, e.g., as follows: the ordered pair $(-5, +2)$ means that the disk $D_1$ is $5$ units to the left of its initial position, and the disk $D_2$ is $+2$ units to the right of its initial position. Since each of the two positions forming an ordered pair can range over any of the above-mentioned $11$ number of different values, there are, in all, $11 \times 11 = 121$ number of such possible ordered pairs in the Cartesian product.

For each one of these $121$ different pairs, we use the above-given formula to determine what the energy of each compartment is like. Then, we add the three energies (of the three compartments) together to get the value of the energy of the system as a whole.

In short, we get a set of $121$ possible values for the energy of the system.

You must have noticed that we have admitted every possible permutation into analysis—all the $121$ number of them.

Of course, out of all these $121$ number of permutations of positions, it should turn out that $120$ number of them have to be discarded because they would be merely hypothetical, i.e. unreal. That, in turn, is because, the relative positions of the disks contained in one and only one ordered pair would actually correspond to the final, equilibrium position. After all, if you conduct this experiment in reality, you would always get a very definite pair of the disk-positions, and it this same pair of relative positions that would be observed every time you conducted the experiment (for the same piston displacement). Real experiments are reproducible, and give rise to the same, unique result. (Even if the system were to be probabilistic, it would have to give rise to an exactly identical probability distribution function.) It can’t be this result today and that result tomorrow, or this result in this lab and that result in some other lab. That simply isn’t science.

Thus, out of all those $121$ different ordered-pairs, one and only one ordered-pair would actually correspond to reality; the rest all would be merely hypothetical.

The question now is, which particular pair corresponds to reality, and which ones are unreal. How to tell the real from the unreal. That is the question.

Here, the variational principle says that the pair of relative positions that actually occurs in reality carries a certain definite, distinguishing attribute.

The system-energy calculated for this pair (of relative displacements) happens to carry the lowest magnitude from among all possible $121$ number of pairs. In other words, any hypothetical or unreal pair has a higher amount of system energy associated with it. (If two pairs give rise to the same lowest value, both would be equally likely to occur. However, that is not what provably happens in the current example, so let us leave this kind of a “degeneracy” aside for the purposes of this post.)

(The update on 26 December 2016 begins here:)

Actually, the description  given in the immediately preceding paragraph was a bit too dumbed down. The variational principle is more subtle than that. Explaining it makes this post even longer, but let me give it a shot anyway, at least today.

To follow the actual idea of the variational principle (in a not dumbed-down manner), the procedure you have to follow is this.

First, make a table of all possible relative-position pairs, and their associated energies. The table has the following columns: a relative-position pair, the associated energy $E$ as calculated above, and one more column which for the time being would be empty. The table may look something like what the following (partial) listing shows:

(0,0) -> say, 115 Joules
(-1,0) -> say, 101 Joules
(-2,0) -> say, 110 Joules

(2,2) -> say, 102 Joules
(2,3) -> say, 100 Joules
(2,4) -> say, 101 Joules
(2,5) -> say, 120 Joules

(5,0) -> say, 135 Joules

(5,5) -> say 117 Joules.

Having created this table (of $121$ rows), you then pick each row one by and one, and for the picked up $n$-th row, you ask a question: What all other row(s) from this table have their relative distance pairs such that these pairs lie closest to the relative distance pair of this given row. Let me illustrate this question with a concrete example. Consider the row which has the relative-distance pair given as (2,3). Then, the relative distance pairs closest to this one would be obtained by adding or subtracting a distance of 1 to each in the pair. Thus, the relative distance pairs closest to this one would be: (3,3), (1,3), (2,4), and (2,2). So, you have to pick up those rows which have these four entries in the relative-distance pairs column. Each of these four pairs represents a variation $\delta$ on the chosen state, viz. the state (2,3).

In symbolic terms, suppose for the $n$-th row being considered, the rows closest to it in terms of the differences in their relative distance pairs, are the $a$-th, $b$-th, $c$-th and $d$-th rows. (Notice that the rows which are closest to a given row in this sense, would not necessarily be found listed just above or below that given row, because the scheme followed while creating the list or the vector that is the table would not necessarily honor the closest-lying criterion (which necessarily involves two numbers)—not at least for all rows in the table.

OK. Then, in the next step, you find the differences in the energies of the $n$-th row from each of these closest rows, viz., the $a$-th, $b$-th, $c$-th and $c$-th rows. That is to say, you find the absolute magnitudes of the energy differences. Let us denote these magnitudes as: $\delta E_{na} = |E_n - E_a|$$\delta E_{nb} = |E_n - E_b|$$\delta E_{nc} = |E_n - E_c|$ and $\delta E_{nd} = |E_n - E_d|$.  Suppose the minimum among these values is $\delta E_{nc}$. So, against the $n$-th row, in the last column of the table, you write the value $\delta E_{nc}$.

Having done this exercise separately for each row in the table, you then ask: Which row has the smallest entry in the last column (the one for $\delta E$), and you pick that up. That is the distinguished (or the physically occurring) state.

In other words, the variational principle asks you to select not the row with the lowest absolute value of energy, but that row which shows the smallest difference of energy from one of its closest neighbours—and these closest neighbours are to be selected according to the differences in each number appearing in the relative-distance pair, and not according to the vertical place of rows in the tabular listing. (It so turns out that in this example, the row thus selected following both criteria—lowest energy as well as lowest variation in energy—are identical, though it would not necessarily always be the case. In short, we can’t always get away with the first, too dumbed down, version.)

Thus, the variational principle is about that change in the relative positions for which the corresponding change in the energy vanishes (or has the minimum possible absolute magnitude, in case the positions form a discretely varying, finite set).

(The update on 26th December 2016 gets over here.)

And, it turns out that this approach, too, is indeed able to perfectly predict the final disk-positions—precisely as they actually are observed in reality.

If you allow a continuum of positions (instead of the discrete set of only the $11$ number of different final positions for one disk, or $121$ number of ordered pairs), then instead of taking a Cartesian product of positions, what you have to do is take into account a tensor product of the position functions. The maths involved is a little more advanced, but the underlying algebraic structure—and the predictive principle which is fundamentally involved in the procedure—remains essentially the same. This principle—the variational principle—says:

Among all possible variations in the system configurations, that system configuration corresponds to reality which has the least variation in energy associated with it.

(This is a very rough statement, but it will do for this post and for a general audience. In particular, we don’t look into the issues of what constitute the kinematically admissible constraints, why the configurations must satisfy the field boundary conditions, the idea of the stationarity vs. of a minimum or a maximum, i.e., the issue of convexity-vs.-concavity, etc. The purpose of this post—and our example here—are both simple enough that we need not get into the whole she-bang of the variational theory as such.)

Notice that in this second paradigm, (i) we did not restrict the analysis to only those quantities that are actually taking place in reality; we also included a host (possibly an infinity) of purely hypothetical combinations of quantities too; (ii) we worked with energy, a scalar quantity, rather than with momentum, a vector quantity; and finally, (iii) in the variational method, we didn’t bother about the local details. We took into account the displacements of the disks, but not any displacement at any other point, say in the gas. We did not look into presence or absence of a pulse at one point in the gas as contrasted from any other point in it. In short, we did not discuss the details local to the system either in space or in time. We did not follow the system evolution, at all—not at least in a detailed, local way. If we were to do that, we would be concerned about what happens in the system at the instants and at spatial points other than the initial and final disk positions. Instead, we looked only at a global property—viz. the energy—whether at the sub-system level of the individual compartments, or at the level of the overall system.

The Two Paradigms Contrasted from Each Other:

If we were to follow Newton’s method, it would be impossible—impossible in principle—to be able to predict the final disk positions unless all their motions over all the intermediate transient dynamics (occurring over each moment of time and at each place of the system) were not be traced. Newton’s (or vectorial) method would require us to follow all the details of the entire evolution of all parts of the system at each point on its evolution path. In the variational approach, the latter is not of any primary concern.

Yet, in following the energetics program, we are able to predict the final disk positions. We are able to do that without worrying about what all happened before the equilibrium gets established. We remain concerned only with certain global quantities (here, system-energy) at each of the hypothetical positions.

The upside of the energetics program, as just noted, is that we don’t have to look into every detail at every stage of the entire transient dynamics.

Its downside is that we are able to talk only of the differences between certain isolated (hypothetical) configurations or states. The formalism is unable to say anything at all about any of the intermediate states—even if these do actually occur in reality. This is a very, very important point to keep in mind.

The Question:

Now, the question with which we began this post. Namely, what does the delta of the variational calculus mean?

Referring to the above discussion, note that the delta of the variational calculus is, here, nothing but a change in the position-pair, and also the corresponding change in the energy.

Thus, in the above example, the difference of the state (2,3) from the other close states such as (3,3), (1,3), (2,4), and (2,2) represents a variation in the system configuration (or state), and for each such a variation in the system configuration (or state), there is a corresponding variation in the energy $\delta E_{ni}$ of the system. That is what the delta refers to, in this example.

Now, with all this discussion and clarification, would it be possible for you to clearly state what the physical meaning of the delta is? To what precisely does the concept refer? How does the variation in energy $\delta E$ differ from both the finite changes ($\Delta E$) as well as the infinitesimal changes ($\text{d}E$) of the usual calculus?

Note, the question is conceptual in nature. And, no, not a single one of the very best books on classical mechanics manages to give a very succinct and accurate answer to it. Not even Rana and Joag (or Goldstein, or Feynman, or…)

I will give my answer in my next post, next year. I will also try to apply it to a couple of more interesting (and somewhat more complicated) physical situations—one from engineering sciences, and another from quantum mechanics!

In the meanwhile, think about it—the delta—the concept itself, its (conceptual) meaning. (If you already know the calculus of variations, note that in my above write-up, I have already supplied the answer, in a way. You just have to think a bit about it, that’s all!)

An Important Note: Do bring this post to the notice of the Officially Approved Full Professors of Mechanical Engineering in SPPU, and the SPPU authorities. I would like to know if the former would be able to state the meaning—at least now that I have already given the necessary context in such great detail.

Ditto, to the Officially Approved Full Professors of Mechanical Engineering at COEP, esp. D. W. Pande, and others like them.

After all, this topic—Lagrangian mechanics—is at the core of Mechanical Engineering, even they would agree. In fact, it comes from a subject that is not taught to the metallurgical engineers, viz., the topic of Theory of Machines. But it is taught to the Mechanical Engineers. That’s why, they should be able to crack it, in no time.

(Let me continue to be honest. I do not expect them to be able to crack it. But I do wish to know if they are able at least to give a try that is good enough!)

Even though I am jobless (and also nearly bank balance-less, and also cashless), what the hell! …

…Season’s greetings and best wishes for a happy new year!

A Song I Like:

[With jobless-ness and all, my mood isn’t likely to stay this upbeat, but anyway, while it lasts, listen to this song… And, yes, this song is like, it’s like, slightly more than 60 years old!]

(Hindi) “yeh raat bhigee bhigee”
Music: Shankar-Jaikishan
Singers: Manna De and Lata Mangeshkar
Lyrics: Shailendra

[E&OE]

/

# See, how hard I am trying to become an Approved (Full) Professor of Mechanical Engineering in SPPU?—2

Remember the age-old decade-old question, viz.:

“Stress or strain: which one is more fundamental?”

I myself had posed it at iMechanica about a decade ago [^]. Specifically, on 8th March 2007 (US time, may be EST or something).

The question had generated quite a bit of discussion at that time. Even as of today, this thread remains within the top 5 most-hit posts at iMechanica.

In fact, as of today, with about 1.62 lakh reads (i.e. 162 k hits), I think, it is the second most hit post at iMechanica. The only post with more hits, I think, is Nanshu Lu’s, providing a tutorial for the Abaqus software [^]; it beats mine like hell, with about 5 lakh (500 k) hits! The third most hit post, I think, again is about sharing scripts for the Abaqus software [^]; as of today, it lags mine very closely, but could overtake mine anytime, with about 1.48 lakh (148 k) hits already. There used to be a general thread on Open Source FEM software that used to be very close to my post. As of today, it has fallen behind a bit, with about 1.42 lakh (142 k) hits [^]. (I don’t know, but there could be other widely read posts, too.)

Of course, the attribute “most hit” is in no fundamental way related to “most valuable,” “most relevant,” or even “most interesting.”

Yet, the fact of the matter also is that mine is the only one among the top 5 posts which probes on a fundamental theoretical aspect. All others seem to be on software. Not very surprising, in a way.

Typically, hits get registered for topics providing some kind of a practical service. For instance, tips and tutorials on software—how to install a software, how to deal with a bug, how to write a sub-routine, how to produce visualizations, etc. Topics like these tend to get more hits. These are all practical matters, important right in the day-to-day job or studies, and people search the ‘net more for such practically useful services. Precisely for this reason—and especially given the fact that iMechanica is a forum for engineers and applied scientists—it is unexpected (at least it was unexpected to me) that a “basically useless” and “theoretical” discussion could still end up being so popular. There certainly was a surprise about it, to me. … But that’s just one part.

The second, more interesting part (i.e., more interesting to me) has been that, despite all these reads, and despite the simplicity of the concepts involved (stress and strain), the issue went unresolved for such a long time—almost a decade!

Students begin to get taught these two concepts right when they are in their XI/XII standard. In my XI/XII standard, I remember, we even had a practical about it: there was a steel wire suspended from a cantilever near the ceiling, and there was hook with a supporting plate at the bottom of this wire. The experiment consisted of adding weights, and measuring extensions. … Thus, the learning of these concepts begins right around the same time that students are learning calculus and Newton’s  3 laws… Students then complete the acquisition of these two concepts in their “full” generality, right by the time they are just in the second- or third-year of undergraduate engineering. The topic is taught in a great many branches of engineering: mechanical, civil, aerospace, metallurgical, chemical, naval architecture, and often-times (and certainly in our days and in COEP) also electrical. (This level of generality would be enough to discuss the question as posed at iMechanica.)

In short, even if the concepts are so “simple” that UG students are routinely taught them, a simple conceptual question involving them could go unresolved for such a long time.

It is this fact which was (honestly) completely unexpected to me, at least at the time when I had posed the question.

I had actually thought that there would surely be some reference text/paper somewhere that must have considered this aspect already, and answered it. But I was afraid that the answer (or the reference in which it appears) could perhaps be outside of my reach, my understanding of continuum mechanics. (In particular, I knew only a little bit of tensor calculus—only that as given in Malvern, and in Schaum’s series, basically. (I still don’t know much more about tensor calculus; my highest reach for tensor calculus remains limited to the book by Prof. Allan Bower of Brown [^].)) Thus, the reason I wrote the question in such a great detail (and in my replies, insisted on discussing the issues in conceptual details) was only to emphasize the fact that I had no hi-fi tensor calculus in mind; only the simplest physics-based and conceptual explanation was what I was looking for.

And that’s why, the fact that the question went unresolved for so long has also been (actually) fascinating to me. I (actually) had never expected it.

And yes, “dear” Officially Approved Mechanical Engineering Professors at the Savitribai Phule Pune University (SPPU), and authorities at SPPU, as (even) you might have noticed, it is a problem concerning the very core of the Mechanical Engineering proper.

I had thought once, may be last year or so, that I had finally succeeded in nailing down the issue right. (I might have written about it on this blog or somewhere else.) But, still, I was not so sure. So, I decided to wait.

I now have come to realize that my answer should be correct.

I, however, will not share my answer right away. There are two reasons for it.

First, I would like it if someone else gives it a try, too. It would be nice to see someone else crack it, too. A little bit of a wait is nothing to trade in for that. (As far as I am concerned, I’ve got enough “popularity” etc. just out of posing it.)

Second, I also wish to see if the Officially Approved Mechanical Engineering Professors at the Savitribai Phule Pune University (SPPU)) would be willing and able to give it a try.

(Let me continue to be honest. I do not expect them to crack it. But I do wish to know whether they are able to give it a try.)

In fact, come to think of it, let me do one thing. Let me share my answer only after one of the following happens:

• either I get the Official Approval (and also a proper, paying job) as a Full Professor of Mechanical Engineering at SPPU,
• or, an already Officially Approved Full Professor of Mechanical Engineering at SPPU (especially one of those at COEP, especially D. W. Pande, and/or one of those sitting on the Official COEP/UGC Interview Panels for faculty interviews at SPPU) gives it at least a try that is good enough. [Please note, the number of hits on the international forum of iMechanica, and the nature of the topic, once again.]

I will share my answer as soon as either of the above two happens—i.e., in the Indian government lingo: “whichever is earlier” happens.

But, yes, I am happy that I have come up with a very good argument to finally settle the issue. (I am fairly confident that my eventual answer should also be more or less satisfactory to those who had participated on this iMechanica thread. When I share my answer, I will of course make sure to note it also at iMechanica.)

This time round, there is not just one song but quite a few of them competing for inclusion on the “A Song I Like” section. Perhaps, some of these, I have run already. Though I wouldn’t mind repeating a song, I anyway want to think a bit about it before finalizing one. So, let me add the section when I return to do some minor editing later today or so. (I certainly want to get done with this post ASAP, because there are other theoretical things that beckon my attention. And yes, with this announcement about the stress-and-strain issue, I am now going to resume my blogging on topics related to QM, too.)

Update at 13:40 hrs (right on 19 Dec. 2016): Added the section on a song I like; see below.

A Song I Like:

(Marathi) “soor maagoo tulaa mee kasaa? jeevanaa too tasaa, mee asaa!”
Lyrics: Suresh Bhat
Music: Hridaynath Mangeshkar
Singer: Arun Date

It’s a very beautiful and a very brief poem.

As a song, it has got fairly OK music and singing. (The music composer could have done better, and if he were to do that, so would the singer. The song is not in a bad shape in its current form; it is just that given the enormously exceptional talents of this composer, Hridaynath Mangeshkar, one does get a feel here that he could have done better, somehow—don’t ask me how!) …

I will try to post an English translation of the lyrics if I find time. The poem is in a very, very simple Marathi, and for that reason, it would also be very, very easy to give a rough sense of it—i.e., if the translation is to be rather loose.

The trouble is, if you want to keep the exact shade of the words, it then suddenly becomes very difficult to translate. That’s why, I make no promises about translating it. Further, as far as I am concerned, there is no point unless you can convey the exact shades of the original words. …

Unless you are a gifted translator, a translation of a poem almost always ends up losing the sense of rhythm. But even if you keep a more modest aim, viz., only of offering an exact translation without bothering about the rhythm part, the task still remains difficult. And it is more difficult if the original words happen to be of the simple, day-to-day usage kind. A poem using complex words (say composite, Sanskrit-based words) would be easier to translate precisely because of its formality, precisely because of the distance it keeps from the mundane life… An ordinary poet’s poem also would be easy to translate regardless of what kind of words he uses. But when the poet in question is great, and uses simple words, it becomes a challenge, because it is difficult, if not impossible, to convey the particular sense of life he pours into that seemingly effortless composition. That’s why translation becomes difficult. And that’s why I make no promises, though a try, I would love to give it—provided I find time, that is.

Second Update on 19th Dec. 2016, 15:00 hrs (IST):

A Translation of the Lyrics:

I offer below a rough translation of the lyrics of the song noted above. However, before we get to the translation, a few notes giving the context of the words are absolutely necessary.

Notes on the Context:

Note 1:

Unlike in the Western classical music, Indian classical music is not written down. Its performance, therefore, does not have to conform to a pre-written (or a pre-established) scale of tones. Particularly in the Indian vocal performance, the singer is completely free to choose any note as the starting note of his middle octave.

Typically, before the actual singing begins, the lead singer (or the main instrument player) thinks of some tone that he thinks might best fit how he is feeling that day, how his throat has been doing lately, the particular settings at that particular time, the emotional interpretation he wishes to emphasize on that particular day, etc. He, therefore, tentatively picks up a note that might serve as the starting tone for the middle octave, for that particular performance. He makes this selection not in advance of the show and in private, but right on the stage, right in front of the audience, right after the curtain has already gone up. (He might select different octaves for two successive songs, too!)

Then, to make sure that his rendition is going to come out right if he were to actually use that key, that octave, what he does is to ask a musician companion (himself on the stage besides the singer) to play and hold that note on some previously well-tuned instrument, for a while. The singer then uses this key as the reference, and tries out a small movement or so. If everything is OK, he will select that key.

All this initial preparation is called (Hindi) “soor lagaanaa.” The part where the singer turns to the trusted companion and asks for the reference note to be played is called (Hindi) “soor maanganaa.” The literal translation of the latter is: “asking for the tone” or “seeking the pitch.”

After thus asking for the tone and trying it out, if the singer thinks that singing in that specific key is going to lead to a good concert performance, he selects it.

At this point, both—the singer and that companion musician—exchange glances at each other, and with that indicate that the tone/pitch selection is OK, that this part is done. No words are exchanged; only the glances. Indian performances depend a great deal on impromptu variations, on improvizations, and therefore, the mutual understanding between the companion and the singer is of crucial importance. In fact, so great is their understanding that they hardly ever exchange any words—just glances are enough. Asking for the reference key is just a simple ritual that assures both that the mutual understanding does exist.

And after that brief glance, begins the actual singing.

Note 2:

Whereas the Sanskrit and Marathi word “aayuShya” means life-span (the number of years, or the finite period that is life), the Sanskrit and Marathi word “jeevan” means Life—with a capital L. The meaning of “jeevan” thus is something like a slightly abstract outlook on the concrete facts of life. It is like the schema of life. The word is not so abstract as to mean the very Idea of Life or something like that. It is life in the usual, day-to-day sense, but with a certain added emphasis on the thematic part of it.

Note 3:

Here, the poet is addressing this poem to “jeevan” i.e., to the Life with a capital L (or the life taken in its more abstract, thematic sense). The poet is addressing Life as if the latter is a companion in an Indian singing concert. The Life is going to help him in selecting the note—the note which would define the whole scale in which to sing during the imminent live performance. The Life is also his companion during the improvisations. The poem is addressed using this metaphor.

Now, my (rough) translation:

The Refrain:
[Just] How do I ask you for the tone,
Life, you are that way [or you follow some other way], and I [follow] this way [or, I follow mine]

Stanza 1:
You glanced at me, I glanced at you,
[We] looked full well at each other,
Pain is my mirror [or the reference instrument], and [so it is] yours [too]

Stanza 2:
Even once, to [my] mind’s satisfaction,
You [oh, Life] did not ever become my [true]  mate
[And so,] I played [on this actual show of life, just whatever] the way the play happened [or unfolded]

And, finally, Note 4 (Yes, one is due):

There is one place where I failed in my translation, and most any one not knowing both the Marathi language and the poetry of Suresh Bhat would.

In Marathi, “tu tasaa, [tar] mee asaa,” is an expression of a firm, almost final, acknowledgement of (irritating kind of) differences. “If you must insist on being so unreasonable, then so be it—I am not going to stop following my mind either.” That is the kind of sense this brief Marathi expression carries.

And, the poet, Suresh Bhat, is peculiar: despite being a poet, despite showing exquisite sensitivity, he just never stops being manly, at the same time. Pain and sorrow and suffering might enter his poetry; he might acknowledge their presence through some very sensitively selected words. And yet, the underlying sense of life which he somehow manages to convey also is as if he is going to dismiss pain, sorrow, suffering, etc., as simply an affront—a summarily minor affront—to his royal dignity. (This kind of a “royal” sense of life often is very well conveyed by ghazals. This poem is a Marathi ghazal.) Thus, in this poem, when Suresh Bhat agrees to using pain as a reference point, the words still appear in such a sequence that it is clear that the agreement is being conceded merely in order to close a minor and irritating part of an argument, that pain etc. is not meant to be important even in this poem let alone in life. Since the refrain follows immediately after this line, it is clear that the stress gets shifted to the courteous question which is raised following the affronts made by one fickle, unfaithful, even idiotic Life—the question of “Just how do I treat you as a friend? Just how do I ask you for the tone?” (The form of “jeevan” or Life used by Bhat in this poem is masculine in nature, not neutral the way it is in normal Marathi.)

I do not know how to arrange the words in the translation so that this same sense of life still comes through. I simply don’t have that kind of a command over languages—any of the languages, whether Marathi or English. Hence this (4th) note. [OK. Now I am (really) done with this post.]

Anyway, take care, and bye for now…

Update on 21st Dec. 2016, 02:41 AM (IST):

Realized a mistake in Stanza 1, and corrected it—the exchange between yours and mine (or vice versa).

[E&OE]

/

# See, how hard I am trying to become a (Full) Professor of Mechanical Engineering in SPPU?

Currently, I am not only cashless but also jobless. That’s why, I try harder.

I am trying very hard to be a (Full) Professor of Mechanical Engineering, especially at the Savitribai Phule Pune University (or SPPU for short).

That’s right.

And that’s why, I have decided to adopt an official position whereby I abandon all my other research and study interests, especially those related to the mechanics of the quanta. Instead, I have officially decided to remain interested only in the official problems from the Mechanical Engineering discipline proper—not only for my studies, but also for my research interests.

… If only I were to have my first degree in Mechanical Engineering, instead of in Metallurgy! (It was some 37.5–33.5 years ago, with my decision to choose Metallurgy being from some 36.5 years ago.) … If only I were to choose Mechanical right back then, this problem wouldn’t have arisen today. …

Tch! …

…But, well, thinking of my first degree, its circumstances—where I got it from (COEP, the engineering college with the highest cut-off merit in the entire Maharashtra state), in what class (First Class with Distinction, the highest class possible), and, most crucially, for spending all my time at what place (The Boat Club)… You know, looking back some 3.5 decades later of all those circumstances—the circumstances of how I chose Metallurgy, back then, as I was sitting at the Boat Club… Hmmm… Boat Club. … Boat Club! Boat Club!!

It gives me some ideas.

So, to better support my current endeavors of becoming an Officially Approved Full Professor of Mechanical Engineering in SPPU, may be, I should solve some Mechanical Engineering problems related to boats. Preferably, those involving not just fluid mechanics, but also mechanisms and machine design—and vibrations! [Oh yes. I must not forget them! Vibrations are, Officially, a Mechanical Engineering topic. In fact even Acoustics. …]

Thinking along such lines, I then thought of one problem, and sort of solved it too. Though I am not going to share my answer with you, I certainly want to share the problem itself with you. (Don’t ask me for answers until I get the job as an Officially Approved Full Professor in Mechanical Engineering at SPPU.)

OK, so here we go.

The Problem Description:

Consider a boat floating on a stand-still lake. The boat has a very simple shape; it is in the shape of a rectangular parallelpiped (i.e., like a shoe-box, though not quite exactly like a punt).

In the plan (i.e. the top view), the boat looks like this:

As shown in the figure, at the centers of the front- and back-sides of the boat, there are two circular cylindrical cavities of identical dimensions, both being fitted with reciprocating pistons. These pistons are being driven by two completely independent mechanisms. The power-trains and the prime-movers are not shown in the diagram; in this analysis, both may be taken to be mass-less and perfectly rigid. However, the boat is assumed to have some mass.

We will try to solve for the simplest possible case: perfectly rigid boat walls (with some mass), perfectly rigid but mass-less pistons, complete absence of friction between the pistons and the cylinder walls, etc.

Assume also that both the boat and the lake water are initially stand-still, and that there are no other influences affecting the motions (such as winds or water currents).

Now, let’s put the pistons in oscillatory motions. In general, the frequencies of their oscillations are not equal. Let the frequency for the left- and right-side pistons be $f_L$ and $f_R$ Hz, respectively.

Problem 1:

Build a suitable Mechanical Engineering model, and predict how the boat would move, in each of the following three scenarios:

• $f_L = f_R$
• $f_L > f_R$
• $f_L < f_R$

In each case, determine (i) whether the boat as a whole (i.e. its center of mass or CM) would at all undergo any motion at all or not, (ii) if yes, whether the motion of the CM would have an element of oscillations to it or not, and finally, (iii) whether the boat (i.e. its CM) would undergo a net displacement over a large number of pistons oscillations or not (i.e., the question asks whether the so-called “time-averaged” net displacement occurs in any one direction or not), and if yes, in which direction.

You may make other minor assumptions. For instance, in each of the above 3 cases, you may assume that at time $t = 0$, both the pistons are at their innermost positions, with each piston beginning its motion by pushing outwards. Also check out the effect of assuming, some other, suitable, values for the initial phases.

Though not at all necessary, if it will help you, you may perhaps consider the case where the higher frequency is an integer multiple of the lower frequency, e.g., in the second of the three cases, assume $f_L = n f_R$, where $n \in \mathcal{N}$. However, note that eventually, you are expected to solve the problem in the general case, the one in which the ratio of the frequencies may be any real number. The cases of practical interest may be where the ratio ranges from 0.0 to a real number up to, say, 2.67 or 3.14 (or, may be, 5.25).

Notice that nowhere thus far have we said that the oscillatory motion of the pistons would be SHM (i.e. simple harmonic). You may begin with an SHM, but as a further problem below illustrates, the piston motion may neither be simple-harmonic, nor even symmetrical in the to- and fro-directions.

On the fluid mechanics side: In your analysis, assume that the length of the boat is much, much greater than the stroke-lengths of the pistons. Essentially, we want to ensure that the water waves produced at one end do not significantly affect the local dynamics at the other end.

You may assume a highly simplified model for the fluid—the problem is not supposed to have a crucial bearing on what kind of a fluid you assume. I mean to say, we are not looking for so detailed a model that you would have to perform a CFD analysis. (That task, we will leave to the Naval Architecture engineers.) However, do make sure to note how your model behaves for an inviscid flow vs. for a viscous flow.

So, in short, the problem is to determine the nature of the motion of the boat, if there is any—i.e., to determine if its CM undergoes a net displacement in the time-averaged sense or not, and if yes, in which direction it occurs.

Problem 2:

Assume a relatively smaller stroke-length for one of the pistons, and repeat the problem.

Problem 3:

Assume that one of the frequencies is zero, which is as good as saying that the boat is fitted with only one cylinder-and-piston. Repeat the analysis.

Problem 4:

Continue to assume that one of the frequencies is zero. Now, also assume that the outward stroke of the moving piston happens faster than its inward stroke. Determine the nature of the motion, if any, for the CM of the boat.

Problem 5 (Optional):

Assuming that the prime mover outputs a uniform circular (or rotary) motion, design a suitable mechanism which will help implement the idea of having non-SHM motions—e.g., different stroke-times in the outward and inward directions. Conduct an informal (or a more formal, calculus-based) displacement-, velocity- and acceleration-analysis, if you wish.

Give it a thought whether this entire idea of transforming a circular motion to a nonuniform reciprocating motion can be done away with, thereby saving on energy—in real life, there is friction—using certain ideas from electrical engineering and electronics.

Ooops!

No, no, no! No!! Throw out that horrendous idea! I mean the very last one!!

We want to remain concerned only with the Mechanical Engineering Problems proper. That is the Official position I have adopted, remember?

That’s right. What I described above was, really, really, really only a Mechanical Engineering Problem.

It really, really, really has nothing to do with anything else such as electrical engineering or quantum physics.

[And if even Prof. Thanu Padmanabhan (IUCAA) does not know quantum physics (he told me so once, right in person), why should I be concerned with it, anyway?]

Anyway, so, Officially speaking, I made up this problem only because I want to become an Officially Approved Full Professor of Mechanical Engineering at SPPU.

If you are interested in some other Mechanical Engineering problems, especially on the fluids-thermal side, check out my recent posts on the Eco-Cooler, and see if you can take further the analysis given in them.

I myself had made a much more advanced engineering analysis right at that time, but I am not going to give it—or its results—until some time after I land and join the kind of job I am looking for—a Full Professor’s. (And I hope that you do have the sense to see that this is not a “prestige issue” on my part.)

The post having a preliminary (quantitative) fluids-thermal analysis is here [^], though the qualitative analysis of the problem begins with an earlier post, here [^].

[Guess the problem, as given, is enough for the time being. I may even come back and add one or two variations on the problem! But no guarantees.]

Update right on 2016.12.02: OK, here are a couple of minor variations. What happens if, when a piston comes to a rest at the extreme stroke, it continues staying idle for a while, before resuming its towards-the-center motion? What if the piston motion is such that the point of zero displacement does not occur exactly at the middle of its overall stroke-length?

I may post some further variations on the problem, or suggest alternative analogous problems, in future.

Currently, I am not just cashless but also jobless. That’s why, I try harder.

More, may be later. As to the Song I Like section, I don’t have anything playing at the back of my mind right away, so let me see if something strikes me by the time I come back tomorrow to give a final editing touch to this post. In that case, I will add this section; else, I will not!

[After the update right on 2016.12.02: I am done with this post now, and if there are any errors, I will let them stay. If you find the post confusing somewhere, please do drop me a line, though. Best, and take care.]

[E&OE]

# Miscellaneous: my job situation, the Tatas, and taking a break…

The Diwali is here, already!

This year’s Diwali isn’t going great for me. I am still jobless—without reason or rhyme. It is difficult to enjoy Diwali against that backdrop.

As you know, engineering colleges affiliated to the Savitribai Phule Pune University (SPPU for short) have been telling me that my Metallurgy+Mechanical background isn’t acceptable, even though the rules have changed to the contrary, and say that I now qualify (in my interpretation).

Recently I attended an interview, and it seems like I may be able to obtain a clear-cut answer on my eligibility (i.e. the equivalence of Metallurgy and Mechanical) from SPPU.

The thing is, SPPU has been having no Dean for its Engineering faculty for about a year or more by now, because the Maharashtra state government hasn’t so far undertaken the procedure to elect (or select) the next Dean.

This recent interview which I mentioned above, was for a Principal’s post, and I was short-listed. As is the common practice here, the short-listed candidates were all invited at the same time, and thus, I had an opportunity to interact with these other, senior-level professors.

These senior professors (some of them already active as Principals at other colleges) told me that it isn’t just SPPU, but all the universities in Maharashtra. They all are currently having only an in-charge or acting Dean for their engineering faculties, because the procedure to appoint the next set of Deans, which was due to occur this month (October) has once again been postponed by yet another year.

Policy decisions such as the Metallurgy and Mechanical equivalence at SPPU have been pending, they told me, because the acting Dean can easily say that he has no powers to do that. Though the other universities are clear that I would qualify, if a genius running an engineering college under SPPU thinks that I don’t, then the matter normally goes to the Dean. If the Dean is not official, if he is only acting, he doesn’t want to take “risk,” so he takes no decision at all. Not just the equivalence issues, there are certain other policy decisions too, which have been pending, they told me. The in-charge Deans have been processing only the routine work, and not taking any policy decisions. The next set of Deans were expected to get appointed by June 2016, and then, after postponement, by October 2016. (“achhchhe din!”)

Now that the appointments have been officially postponed by one whole year (“achhchhe din,” again!), the colleges themselves have begun going to the universities for obtaining the professor’s approvals, arguing that faculty approvals is a routine matter, and that they cannot properly function without having approved faculty.

Thus, the university (SPPU) has begun appointing panels for faculty interviews. There has been a spate of faculty recruitment ads after the current semester got going (“achhchhe din!”).

The particular interview which I attended, these other candidates informed me, was with a University-appointed panel—i.e., of the kind which allows approvals. (Otherwise, the appointments are made by the affiliating colleges on their own, but only on a temporary, ad-hoc basis, and therefore, for a limited time.)

Please note, all the above is what I gathered from their talk. I do not know what the situation is exactly like. (Comments concerning “achhchhe din!,” however, are strictly mine.)

But yes, it did turn out that the interview panel here was from the university. Being a senior post (Principal), the panel included both the immediately past Dean (Prof. G. K. Kharate) and the new, in-charge Dean (Prof. Dr. Nerkar, of PVG College, Pune).

During my interview, if the manner in which Prof. Kharate (the past Dean) now said things is any indication, it means that I should now qualify even in the SPPU. This would be according to the new GR about which I had written a few months ago, here [^]. Essentially, Prof. Kharate wondered aloud as to why there was any more confusion because the government had already clarified the situation with the new rules.

I took that to mean that I qualify.

Of course, these SPPU geniuses are what they are, and therefore, they—these same two SPPU Deans—could very well say, in future, that I don’t qualify. After all, I didn’t ask them the unambiguous question “With my Metallurgy background, do I qualify for a Mechanical Engineering (full) Professor’s job or not? Yes, or no?;”  and they didn’t then answer in yes or no terms.

Of course, right in the middle of an on-going job interview couldn’t possibly have been the best time and place to get them to positively confirm that I do qualify. (Their informal indications, however, were clearly along the lines that I do qualify.)

Now that the Diwali break has arrived, the colleges are closed, and so, I would be able to approach Prof. Dr. Nerkar (the currently acting/in-charge Dean) only after a week or so. I intend to do that and have him pin down the issue in clear-cut terms.

At the conclusion of my interview, I told the interview committee exactly the same thing which I told you at the beginning of this post, viz., that this Diwali means darkness to me.

But yes, we can hope that Prof. Dr. Nerkar would issue the clarification at least after the Diwali. If not, I intend to approach Prof. Dr. Gade, the Vice-Chancellor of SPPU. … I could easily do that. I am very social, that way.

And, the other reason is, at the university next door—the Shivaji University—they did answer my email asking them to clarify these branch-equivalence issues. The SPPU is the worst university among the three in the Western Maharashtra region (the other two being, the University of Mumbai and the Shivaji University Kolhapur). [I want to teach in Pune only because it’s my home-town, and thus convenient to me and my family, not because SPPU’s standards are high.]

Anyway, I now do have something in hand to show Prof. Dr. Gade when I see him—the letter from the Shivaji University staff. … At the Shivaji University, I didn’t have to go and see anyone in person there—not even the administrative staff let alone the acting Dean or the Vice-Chancellor. The matter got clarified just via a routine email. There is a simple lesson that SPPU may learn from the Shivaji and Mumbai universities, and under Prof. Dr. Gade, I hope they do.

… Of course, I do also hope that I don’t have to see Prof. Dr. Gade (the Vice-Chancellor). I do hope that meeting just Prof. Dr. Nerkar (the in-charge Dean) should be sufficient.

If they refuse me an appointment, I will get even more social than my usual self—I will approach certain eminent retired people from Pune such as Dr. Bhatkar (the founder of C-DAC) or Dr. Mashelkar (the former Director General of CSIR, India).

Here is a hoping that I don’t have to turn into a social butterfly, and that soon after Diwali, the matters would get moving smoothly. Let’s hope so.

And with that hope in my heart, let me wish you all a very happy and prosperous Diwali. … As to me, I will try to make as much good of a bad situation that I can.

Still, I don’t find myself to be too enthusiastic. I don’t feel like doing much anything. [In a way, I feel tired.] Therefore, I am going to take a break from blogging.

I have managed to write something more on the concept of space. I found that I should be able to finish this series now. I had begun it in 2013; see here [^].

Concepts like space and time are very deep matters, and I still have to get enough clarity on a few issues, though all such remaining issues are relatively quite minor. I should be able to get through them in almost no time.

From the new material which I have written recently, I guess it would be enough to write just one or two posts, and then the series would get over. What then will remain would be mostly polemics, and that part can be taken on the fly whenever the need to do so arises.

I may also think of giving some indications on the concept of time, but, as I said, I find myself too lacking in enthusiasm these days. Being jobless—despite having the kind of resume I have—does have a way of generating a certain amount of boredom in you, a certain degree of disintegration at least to your energy and enthusiasm, even if not to your soul.

So, let’s see. Let the Diwali vacations get over, and I should come back and resume my blogging, telling you what all transpired in my meeting/interaction with the in-charge Dean, and the related matters.

Since I am not going to be blogging for some time, let me note a couple of notable things.

One, the US Presidential elections. I am not at all interested in that. So let me leave it aside.

Two, the Tata Sons issue. It does interest me a bit, so let me write down a bit on it.

I was not as surprised as some of the newspaper editorials and columns say they were. The days of JRD are long gone. The Tatas already were a changed company when Cyrus Mistry took over from Ratan Tata.

Once I returned from the USA in 2001, despite my resume, I never got a chance with the new Tatas (either at TRDDC or at TCS). Such a thing would have been unthinkable during JRD’s times. … Even keeping it aside, what all I observed about the Tatas over the past 1.5 decades was enough for me not to be at all surprised by something like the current fiasco.

No, Prof. Pratap Bhanu Mehta, reading things from where I sit, the Tata fiasco doesn’t do any significant harm to the social legitimacy of Capitalism in India. People—common people—have long ago observed and concluded what had to be. If what the common people think were to be caricatured, it would look like the position you ascribe to the “cynics”. But no, IMO, this position isn’t cynical. To carry realistic impressions about hallowed icons is not quite the same as being a cynic.

Yes, as Harsh Goenka astutely pointed out in his comment in today’s ToI, Ratan Tata’s tenure coincided with the semi-liberalization era: 1991–2012. Whenever you come to compare Ratan Tata with Cyrus Mistry, you cannot overlook that broad context.

I have always thought that JRD left too big shoes for any one to fill in. But, with due respect to Ratan Tata, I still would have to say that no one could possibly entertain thinking in similar terms, when it comes to Ratan Tata’s retirement.

Looking at the facts and figures reported this week, I don’t think Mistry was doing a lousy job. Reading through his letter, I in fact marvel at how well he understood his job—and for this reason, I speculate that he must have been doing his job pretty well. …

Realize, the letter was written within a day or two after an unceremonious removal from the top post of a 100+ years old Indian icon, a \$100 billion behemoth. Seen against this backdrop, the letter is extraordinarily restrained; it shows an unusual level of maturity. To expect any more “restraint” is to actually confess ignorance of such basic things as human nature and character. (Sadhus, let me remind you, are known to kill each other in their fights at the Kumbh Mela, just for the priority in taking the Shahi Snaan. Keep that in mind the next time you utter something on nobility of character and culture.)

And yes, I also had come to think that the Nano project was doomed—I just didn’t have the sales and profitability figures, which got reported only today. My reasons were simple; they were purely from an ordinary consumer’s point of view. If you are selling the Nano at around Rs. 2.5 lakhs, just think of the alternatives that the consumer has today: you could get a used car in a “good enough” condition, not just Maruti Alto but even a somewhat more used Toyota Innova, at roughly the same price.

Anyway, I don’t understand these corporate matters much, so let me shut up.

But, yes, knowing the house of Tatas and their brand managers, I can predict right away that in the near future, you are going to see the Tatas announce a product like “Tata Quantum Dot,” or “Tata Silicon Dot,” or something like that. … Why do I think so?

I started writing on quantum mechanics, and roughly around the same time, the cable-less Internet, based on the electromagnetic waves (mobile, Wi-Fi) was getting going in India. So, the Tatas came out with the Tata Photon. Yes, “Photon”. The Tata Photon. … It meant nothing more than the usual Internet dongle (2G, and then 3G) that everybody else was already supplying anyway. (And the Tata Photon never worked too well in areas other than in the Mumbai city.)

Then, the USA was abuzz with the catch-words like nano-technology, and the Tata brand managers decided to do something with that name, and thus came the Tata “Nano.” By now, every one knows what it means.

Today, the USA and other countries are abuzz with words like “Quantum Supremacy” and things like that. You can only expect some Tata brand managers to latch on to this buzzword, and launch a product like, say, Tata Quantum Dot or Tata Silicon Dot—or both!

Tata Silicon Dot, I predict, would signal the arrival of the house of Tatas into the business of supplying the sand required for civil engineering construction.

Tata Quantum Dot, on the other hand, would mean that the house of Tatas had taken an entry into the business of plastic dart toys. Or, the business of the “bindi”s that ladies wear. That is what the house of Tatas would mean by the name Tata Quantum Dot.

And here our policy analysts think that something happening to the house of Tatas is going to affect the credibility or social legitimacy of Capitalism itself in India! Oh wow!!

Ummm…. Does any policy research center in India have any data on the proportion of the private business in the overall Indian economy (including both the organized and the unorganized sectors) over the years, say starting from 1930s? Also, the quantum of the government expenditure in the Indian economy, and its proportion in the national GDP over the same period? Would they care to share it, please? Or is it that they don’t have to look at such data for their policy research purposes? … As to me, I have been on the lookout for data like that for quite some time now, but never could see it compiled anywhere. That’s why the request. Please drop me a line if you spot a reliable source.

OK, bye for now.

A Song I Like:

Since I won’t be blogging for a while, let me give away the “other” song right away, I mean the song which had somehow happened to strike me as being similar to the song “too laali hai savere waali”; see the Song I Like section here [^]. This other song is:

(Hindi) “bhigee bhigee raaton mein…”
Music: R. D. Burman
Singers: Kishore Kumar, Lata Mangeshkar
Lyrics: Anand Bakshi

I take the “raaga” of the earlier song (“too laali hai”) as “pahaaDee”—or at least that’s what I got from an Internet search. The “raaga” of the current song (“bhigee…”) isn’t listed at any Web site. Assuming it’s not “pahaaDee” (or a variant on that), the question becomes, why the two songs might have struck at least somewhat similar to me—why, humming one song, I very naturally and casually happened to remember the other song.

It would be interesting to see if Data Science can be used to spot (and quantify) similarities in songs. The traditional music theory puts too much emphasis, IMO, on “raaga” alone. But there can be other bases for similarities, too. The sound patterns of musical pieces, I think, don’t get exhaustively (and at times not even essentially) characterized by the idea of the “raaga” alone. Talking of these two songs in particular, the similarity I caught might have been connected with certain ups and downs in notes with a somehow similarly sounding tempo. The style of the tunes sounds similar. Guess Data Science might be able to shed some light on things like that…. It would be interesting, to look into that, no? That’s what I had thought…

I mean, I had thought. … But then, these days, as I said, I am unable to work on this topic, too…  I just don’t have any enthusiasm left. Honest. I somehow finished this post, only because I won’t be posting for a while…

So, there. Bye for now, take care, and best!

[E&OE]

# What are the rules for hiring?—2

Last year in August, I had written a post of the title: “What are the rules for hiring?” [^]. In that post, I had pointed out that historically, the University of Pune (now called Savitribai Phule Pune University, or SPPU for short), in fact didn’t have this “Mechanical-vs-Metallurgy `Branch-Jumping’ Issue.” Though I have a BE in Metallurgy, I myself had taken admission, right in COEP, for an ME program in Mechanical Engineering.

In that post, I had also traced in some detail how COEP had thrown obstacles in my path at the time of my admission to the PhD program in Mechanical Engineering. (If you found (or now find) reading through all those details exasperating, then take a moment to realize what it might have been like for me to live through those artificially created struggles.)

Today, in this post, I once again return to the issue of the hiring rules. I want to provide the reader with copies of the relevant official documents, together with some discussion of the issues as well as my comments.

(I) The AICTE Norms:

If you do ‘net searches to find the AICTE norms document which governs the hiring of professors in the engineering colleges in this country, then you will find many documents floated by different colleges or universities. Most of the matter in such documents are similar to the actual AICTE document, though there often are some small and subtle differences. I don’t mind if different colleges/universities wish to follow policies that are at a slight variance from the norms issued by the AICTE. After all, these are norms, not hard-and-fast rules. To me, trouble begins only when they don’t explicitly note the points of departure. Go ahead, do ‘net searches, and you will find that not a single one of these unofficial documents has bothered to explicitly identify the changes they made from the original AICTE document.

For my purposes, I was looking for the original and authentic AICTE document. I found it faithfully uploaded at SPPU’s Web site, here [^]. Since the college/university Web sites sometimes fail to maintain all the documents or links in order, I have decided to keep a copy of this same document also on my Google Drive, here [^].

See Serial Number 3 on page 2 for Professor’s position in this document. It states:

“Ph.D  degree  with  first  class  degree  at  Bachelor’s  or  Master’s  level  in  the appropriate  branch  of  Engineering  /  Technology  with  10  years  experience in Teaching / Industry / Research out of which 5 years must be at the level of  Assistant  Professor  and  /  or  equivalent.”

True to the khaki register-style dumbness (or the (Marathi) “khaa kee!” type of “smart”ness), this wording is vague on multiple counts. (If there is someone intending to get bribes, let me state it, publicly, that I am refusing to give them any.)

You can interpret this wording in several different ways. The different interpretations can be had by mentally inserting braces “{}” to isolate the different blocks of the text together, and then working out whether these blocks of text apply multiplicatively (as in the Cartesian product) or not.

The two relevant and entirely different ways in which the wording can be interpreted is this:

Interpretation 1.0:

This interpretation says that: you should have a PhD degree in the appropriate branch + you should have a first class either at bachelor’s level or at the master’s level, but both the bachelor’s and the master’s degrees must have come only in the appropriate branch.

According to this interpretation, you are allowed to be dumb (you have to somehow manage a first class only once), so long as you have been conforming to the same branch throughout your life.

With this interpretation, the following issue arises: What does constitute an appropriate branch?

1.1 One sub-interpretation is: Only the Mechanical branch is the appropriate branch for the position of Professor of Mechanical Engineering.

1.2 The other sub-interpretation is: You may have the Mechanical branch either at the bachelor’s or the master’s level (just the way you can have a first class either at bachelor’s or master’s level) but not necessarily at both.

Since I didn’t have a Mechanical degree at either bachelor’s or master’s level, I couldn’t qualify, according to this interpretation 1.0 (whether you follow 1.1 or 1.2).

Interpretation 2.0:

This interpretation says that: You should have a PhD degree in the appropriate branch + you should have a first class either at bachelor’s level or at the master’s level, and further, that either bachelor’s or master’s degrees should have come from an appropriate branch.

Once again, you have to decide what constitutes an appropriate branch.

2.1 One sub-interpretation is: Only the Mechanical branch is the appropriate branch for a position of Professor of Mechanical Engineering.

2.1 The other sub-interpretation is: There can be choices for the appropriate branch at any of the degrees. For instance, to become a Professor of Mechanical Engineering, all the following are OK:
BE (Mech) + ME (Mech) + PhD (Met.)
BE (Mech) + ME (Prod) + PhD (Prod)
BE (Prod) + ME (Prod) + PhD (Prod)
BE (Met) + MTech (Met) + PhD (Mech)—my combination
BE (Aero) + ME (Met) + PhD (Met.)
Etc.

This was my interpretation. It makes sense, because: (i) the wording is: “Bachelor’s or Master’s level in the appropriate branch,” and (ii) the word used is: “the appropriate branch,” not “the same branch.”

The Malady: The interpretation 1.0 was what was adopted by the former Dean of Faculty of Engineering at SPPU, i.e., Dr. G. K. Kharate.

End of (this part of the) story.

(II) The Mumbai University Norms (2012):

The Mumbai University historically had always followed the interpretation 2.2, and never had major issues.

However, in view of the tightening of the government controls, they had held detailed discussions, and then had arrived at an explicit document that clearly states what all constitute the appropriate branches. They published this decision via a document called “Circular No. CONCOL/ICC/04/ of 2012”. I once again link to a copy that I have stored on my Google Drive, here [^].

See page 2 of this document, for the statement qualifications for an Assistant Professor:

“BE/ B Tech and ME /M Tech in relevant subject with First Class or equivalent either in BE / B Tech or ME / M Tech OR ME/M TECH in relevant Subject with First Class”

See page 3 of the same document for additional qualifications for an Associate Professor:

“Qualification as above that is for the post of Assistant Professor, as applicable and PHD or equivalent, in appropriate Discipline”

On the same page, certain additional qualifications expected for a Professor’s position are noted.

See page 9, Serial No. 2 of this document. For a position of Professor in Mechanical Engineering, Metallurgy is included as an equivalent/relevant/appropriate branch, even though only at the master’s level.

However, the drafting is extraordinarily clear here—there are two “or”s—one in the lowercase letters, and another in the capitals. The existence of the capital “OR” makes it abundantly clear that having only a master’s in a relevant subject with First Class is good enough. [Little wonder that the University of Mumbai always cuts ahead of the SPPU on rankings.]

As such, Interpretation 2.2 applies, and I qualify.

I anyway met with their Dean, had it clarified that I indeed do qualify, and eventually, was offered jobs as a Professor of Mechanical Engineering. See my resume regarding these jobs. (The particular link to my resume may change as I update the resume, but it is always accessible from the home page of my personal Web site [^].)

But then, of course, the University of Pune (now SPPU) believes that they are the best and the most conscientious (or least licentious) in the world. So, they were never going to be taken in by the mere fact that the University next door (one which has always been ranked higher by every agency in the world) did easily allow me to function as an employed Professor of Mechanical Engineering. (I anyway do function as a professor of engineering. The only question is: whether they allow me to get employed as one, or not. The lower-ranked SPPU’s geniuses don’t.)

III The Maharashtra State GR (May 2014):

Sorry, on two counts: (i) I cannot give you a direct link to this document at the Web sites of the Maharashtra State Government. I found this document at the Recruitments section of COEP’s Web site, in June 2015, but the document is no longer to be found even at the COEP Web site. (ii) The document is in Marathi, so, my English readers would have to trust me when it comes to the titles of the columns of the relevant table.

Though the GR had come in effect in May 2014, I came to know of it only in June of 2015. The utmost benevolent Mechanical Engineering Professors (and the authorities) at SPPU are still napping dozing off, still getting annoyed when I mention the GR, and still asking me for a copy of this document (with a “knowing” certainty that they would be able to disqualify me in reference even to this GR).

I have once again uploaded my copy of the document to Google Drive, here [^].

Refer to page 13, Serial Number 2. (Fortunately, the Arabic numerals in English and in Marathi are quite similar, because the so-called Arabic numerals had originated in India anyway.)

At the master’s level, the GR expands on even the Mumbai Universities’ list of the equivalent/relevant/appropriate branches (though it cuts down on the Aerospace engineering at the bachelor’s level).

Showing this document, my last employers did offer me a position of Professor in Mechanical Engineering. (No, they didn’t give me the UGC scale. But they did offer me a full Professor’s position—and later on, treated me with full organizational respect that goes with a full Professor’s position.) I even uploaded the internal marks to SPPU’s BCUD Web site, using my own official account.)

Even then, even this year, the Mechanical Engineering geniuses and other employers at the utmost conscientious SPPU are still telling me that I don’t qualify.

As to my last employers, though their college is in Pune and is affiliated to SPPU, their headquarters are in Nagpur, not in Pune. But then, my point is, you don’t have to go so far away as to Nagpur. Go just 75 kms from this filthy place, and as soon as you climb down the Khandala ghat (and with that, also shed your obnoxious conformism of a mindless sort), and you reach a better place.

The Rules for the Maharashtra State Government’s Autonomous Institutes (November, 2014):

These are the latest rules. They apply only to the State Goverment’s Autonomous Institutes—not to the engineering colleges affiliated to SPPU.

But bear in mind that in the view of the State Government (and most every one else), these Autonomous Institutes are supposed to be in the leadership positions; they are supposed to be guide-lamps to the other colleges. It is in this context that their rules become relevant.

I found the document at COEP’s Web site, this year, here [^]. Once again, I have uploaded a copy at my Google Drive, here [^].

See page 3, Paragraph Serial Number 3.2. It says:

“PROFESSOR: Essential: (i)  Ph.D.  Degree  or  equivalent  in  the  concerned  discipline  from  a reputed  institution, preceded  by a UG/PG  Degree in the  relevant  discipline in First Class (or equivalent) with consistently good academic record; ” etc.

Much better (though not as good as the University of Mumbai’s).

Note that the PhD ought to come in the concerned discipline, whereas either the UG or the PG degree should have come from a relevant discipline.

This document thus settles the issue that the Interpretations 1.1 and 2.1 are NOT valid; only the Interpretations 1.2 and 2.2 can be. However, unlike the broadest interpretation in 2.2, here, the requirements are a bit restrictive: your PhD must be in the concerned discipline.

Thus, for the position of Professor in Mechanical Engineering, the following combination is allowed:

BE (Met) + M Tech (Met) + PhD (Mech).

On the other hand, as far as I can make it out (and I can be wrong here), both of the following come in doubt:

BE (Mech) + M Tech (Mech) + PhD (Aero)
BE (Mech) + M Tech (Mech) + PhD (Met)

Looks like they should hire people with better drafting abilities at both COEP as well as in the DTE—and most certainly, and first and foremost, at the AICTE. (Yeah, right. Keep hoping. (AICTE sits in New Delhi.))

I assert that the University of Mumbai’s draft is the best (among those considered above). If you differ, drop me a line.

For obvious reasons, for this post, there won’t be the usual section on a song I like.

I may come back and edit this post, but only for correcting typos/links, or to streamline the write-up.

Since the issues are both legal and important, I may also come back to edit this post any time in a distant future. If so, I will note those (more serious) updates explicitly. (In contrast, the immediate updates merely for streamlining and all, will not be noted explicitly.)

Update 1 on 2016.06.21: Added the detailed rules for Assistant and Associate Professor’s positions at the University of Mumbai. [The link to original document was given even earlier, but now the text of the main post also quotes the detailed requirements.]

[E&OE]

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