# Stay tuned to the NSF on the next evening…

Update on 2019.04.10 18:50 IST:

Dimitrios Psaltis, University of Arizona in Tucson, EHT project scientist [^]:

The size and shape of the shadow matches the precise predictions of Einstein’s general theory of relativity, increasing our confidence in this century-old theory. Imaging a black hole is just the beginning of our effort to develop new tools that will enable us to interpret the massively complex data that nature gives us.”

Update over.

Stay tuned to the NSF on the next evening (on 10th April 2019 at 06:30 PM IST) for an announcement of astronomical proportions. Or so it is, I gather. See: “For Media” from NSF [^]. Another media advisory made by NSF roughly 9 days ago, i.e. on the Fool’s Day, here [^]. Their news “report”s [^].

No, I don’t understand the relativity theory. Not even the “special” one (when it’s taken outside of its context of the so-called “classical” electrodynamics)—let alone the “general” one. It’s not one of my fields of knowledge.

But if I had to bet my money then, based purely on my grasp of the sociological factors these days operative in science as practised in the Western world, then I would bet a good amount (even Indian Rs. 1,000/-) that the announcement would be just a further confirmation of Einstein’s theory of general relativity.

That’s how such things go, in the Western world, today.

In other words, I would be very, very, very surprised—I mean to say, about my grasp of the sociology of science in the Western world—if they found something (anything) going even apparently contrary to any one of the implications of any one of Einstein’s theories. Here, emphatically, his theory of the General Relativity.

That’s all for now, folks! Bye for now. Will update this post in a minor way when the facts are on the table.

TBD: The songs section. Will do that too, within the next 24 hours. That’s a promise. For sure. (Or, may be, right tonight, if a song nice enough to listen to, strikes me within the next half an hour or so… Bye, really, for now.)

A song I like:

(Hindi) “ek haseen shaam ko, dil meraa kho_ gayaa…”
Lyrics: Raajaa Mehdi Ali Khaan
Singer: Mohammad Rafi [Some beautiful singing here…]

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# Further on QM, and on changing tracks over to Data Science

OK. As decided, I took a short trip to IIT Bombay, and saw a couple of professors of physics, for very brief face-to-face interactions on the 28th evening.

No chalk-work at the blackboard had to be done, because both of them were very busy—but also quick, really very quick, in getting to the meat of the matter.

As to the first professor I saw, I knew beforehand that he wouldn’t be very enthusiastic with any alternatives to anything in the mainstream QM.

He was already engrossed in a discussion with someone (who looked like a PhD student) when I knocked at the door of his cabin. The prof immediately mentioned that he has to finish (what looked like a few tons of) pending work items, before going away on a month-long trip just after a couple of days! But, hey, as I said (in my last post), directly barging into a professor’s cabin has always done wonders for me! So, despite his having some heavy^{heavy} schedule, he still motioned me to sit down for a quick and short interaction.

The three of us (the prof, his student, and me) then immediately had a very highly compressed discussion for some 15-odd minutes. As expected, the discussion turned out to be not only very rapid, and also quite uneven, because there were so many abrupt changes to the sub-topics and sub-issues, as they were being brought up and dispatched in quick succession. …

It was not an ideal time to introduce my new approach, and so, I didn’t. I did mention, however, that I was trying to develop some such a thing. The professor was of the opinion that if you come up with a way to do faster simulations, it would always be welcome, but if you are going to argue against the well-established laws, then… [he just shook head].

I told him that I was clear, very clear on one point. Suppose, I said, that I have a complex-valued field that is defined only over the physical 3D, and suppose further that my new approach (which involves such a 3D field) does work out. Then, suppose further that I get essentially the same results as the mainstream QM does.

In such a case, I said, I am going to say that here is a possibility of looking at it as a real physical mechanism underlying the QM theory.

And if people even then say that because it is in some way different from the established laws, therefore it is not to be taken seriously, then I am very clear that I am going to say: “You go your way and I will go mine.”

But of course, I further added, that I still don’t know yet how the calculations are done in the mainstream QM for the interacting electrons—that is, without invoking simplifying approximations (such as the fixed nucleus). I wanted to see how these calculations are done using the computational modeling approach (not the perturbation theory).

It was at this point that the professor really got the sense of what I was trying to get at. He then remarked that variational formulations are capable enough, and proceeded to outline some of their features. To my query as to what kind of an ansatz they use, and what kind of parameters are involved in inducing the variations, he mentioned Chebyshev polynomials and a few other things. The student mentioned the Slater determinants. Then the professor remarked that the particulars of the ansatz and the particulars of the variational techniques were not so crucial because all these techniques ultimately boil down to just diagonalizing a matrix. Somehow, I instinctively got the idea that he hasn’t been very much into numerical simulations himself, which turned out to be the case. In fact he immediately said so himself: “I don’t do wavefunctions. [Someone else from the same department] does it.” I decided to see this other professor the next day, because it was already evening (almost approaching 6 PM or so).

A few wonderful clarifications later, it was time for me to leave, and so I thanked the professor profusely for accommodating me. The poor fellow didn’t even have the time to notice my gratitude; he had already switched back to his interrupted discussion with the student.

But yes, the meeting was fruitful to me because the prof did get the “nerve” of the issue right, and in fact also gave me two very helpful papers to study, both of them being review articles. After coming home, I have now realized that while one of them is quite relevant to me, the other one is absolutely god-damn relevant!

Anyway, after coming out of the department on that evening, I was thinking of calling my friend to let him know that the purpose of the visit to the campus was over, and thus I was totally free. While thinking about calling him and walking through the parking lot, I just abruptly noticed a face that suddenly flashed something recognizable to me. It was this same second professor who “does wavefunctions!”

I had planned on seeing him the next day, but here he was, right in front me, walking towards his car in a leisurely mood. Translated, it meant: he was very much free of all his students, and so was available for a chat with me! Right now!! Of course, I had never had made any acquaintance with him in the past. I had only browsed through his home page once in the recent times, and so could immediately make out the face, that’s all. He was just about to open the door of his car when I approached him and introduced myself. There followed another intense bout of discussions, for another 10-odd minutes.

This second prof has done numerical simulations himself, and so, he was even faster in getting a sense of what kind of ideas I was toying with. Once again, I told him that I was trying for some new ideas but didn’t get any deeper into my approach, because I myself still don’t know whether my approach will produce the same results as the mainstream QM does or not. In any case, knowing the mainstream method of handling these things was crucial, I said.

I told him how, despite my extensive Internet searches, I had not found suitable material for doing calculations. He then said that he will give me the details about a book. I should study this book first, and if there are still some difficulties or some discussions to be had, then he would be available, but the discussion would then have to progress in reference to what is already given in that book. Neat idea, this one was, perfect by me. And turns out that the book he suggested was neat—absolutely perfectly relevant to my needs, background as well as preparation.

And with that ends this small story of this short visit to IIT Bombay. I went there with a purpose, and returned with one 50 page-long and very tightly written review paper, a second paper of some 20+ tightly written pages, and a reference to an entire PG-level book (about 500 pages). All of this material absolutely unknown to me despite my searches, and as it seems as of today, all of it being of utmost relevance to me, my new ideas.

But I have to get into Data Science first. Else I cannot survive. (I have been borrowing money to fend off the credit card minimum due amounts every month.)

So, I have decided to take a rest for today, and from tomorrow onwards, or may be a day later—i.e., starting from the “shubh muhurat” (auspicious time) of the April Fool’s day, I will begin my full-time pursuit of Data Science, with all that new material on QM only to be studied on a part-time basis. For today, however, I am just going to be doing a bit of a time-pass here and there. That’s how this post got written.

Take care, and wish you the same kind of luck as I had in spotting that second prof just like that in the parking lot. … If my approach works, then I know who to contact first with my results, for informal comments on them. … I wish you this same kind of a luck…

Work hard, and bye for now.

A song I like
(Marathi) “dhunda_ madhumati raat re, naath re…”
Music: Master Krishnarao
Singer: Lata Mangeshkar

[A Marathi classic. Credits are listed in a purely random order. A version that seems official (released by Rajshri Marathi) is here: [^] . However, somehow, the first stanza is not complete in it.

As to the set shown in this (and all such) movies, right up to, say the movie “Bajirao-Mastani,” I have—and always had—an issue. The open wide spaces for the palaces they show in the movies are completely unrealistic, given the technology of those days (and the actual remains of the palaces that are easy to be recalled by anyone). The ancients (whether here in India or at any other place) simply didn’t have the kind of technology which is needed in order to build such hugely wide internal (covered) spaces. Neitehr the so-called “Roman arch” (invented millenia earlier in India, I gather), nor the use of the monolithic stones for girders could possibly be enough to generate such huge spans. Idiots. If they can’t get even simple calculations right, that’s only to be expected—from them. But if they can’t even recall the visual details of the spans actually seen for the old palaces, that is simply inexcusable. Absolutely thorough morons, these movie-makers must be.]

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# Wrapping up my research on QM—without having to give up on it

Guess I am more or less ready to wrap up my research on QM. Here is the exact status as of today.

1. The status today:

I have convinced myself that my approach (viz. the idea of singular potentials anchored into electronic positions, and with a $3D$ wave-field) is entirely correct, as far as QM of non-interacting particles is concerned. That is to say, as far as the abstract case of two particles in a $0$-potential $1D$ box, or a less abstract but still hypothetical case of two non-interacting electrons in the helium atom, and similar cases are concerned. (A side note: I have worked exclusively with the spinless electrons. I don’t plan to include spin right away in my development—not even in my first paper on it. Other physicists are welcome to include it, if they wish to, any time they like.)

As to the actual case of two interacting particles (i.e., the interaction term in the Hamiltonian for the helium atom), I think that my approach should come to reproduce the same results as those obtained using the perturbation theory or the variational approach. However, I need to verify this part via discussions with physicists.

All in all, I do think that the task which I had intended to complete (and to cross-check) before this month-end, is already over—and I find that I don’t have to give up on QM (as suspected earlier [^]), because I don’t have to abandon my new approach in the first place.

2. A clarification on what had to be worked out and what had to be left alone:

To me, the crucial part at this stage (i.e., for the second-half of March) was verifying whether working with the two ideas of (i) a $3D$ wavefield, and (ii) electrons as “particles” having definite positions (or more correctly, as points of singularities in the potential field), still leads to the same mathematical description as in the mainstream (linear) quantum mechanics or not.

I now find that my new approach leads to the same maths—at least for the QM of the non-interacting particles. And further, I also have very definite grounds to believe that my new approach should also work out for two interacting particles (as in the He atom).

The crucial part at this stage (i.e., for the second half of March) didn’t have so much to do with the specific non-linearity which I have proposed earlier, or the details of the measurement process which it implies. Working out the details of these ideas would have been impossible—certainly beyond the capacities of any single physicist, and over such a short period. An entire team of PhD physicists would be needed to tackle the issues arising in pursuing this new approach, and to conduct the simulations to verify it.

BTW, in this context, I do have some definite ideas regarding how to hasten this process of unraveling the many particular aspects of the measurement process. I would share them once physicists show readiness to pursue this new approach. [Just in case I forget about it in future, let me note just a single cue-word for myself: “DFT”.]

3. Regarding revising the Outline document issued earlier:

Of course, the Outline document (which was earlier uploaded at iMechanica, on 11th February 2019) [^] needs to be revised extensively. A good deal of corrections and modifications are in order, and so are quite a few additions to be made too—especially in the sections on ontology and entanglement.

However, I will edit this document at my leisure later; I will not allocate a continuous stretch of time exclusively for this task any more.

In fact, a good idea here would be to abandon that Outline document as is, and to issue a fresh document that deals with only the linear aspects of the theory—with just a sketchy conceptual idea of how the measurement process is supposed to progress in a broad background context. Such a document then could be converted as a good contribution to a good journal like Nature, Science, or PRL.

4. The initial skepticism of the physicists:

Coming to the skepticism shown by the couple of physicists (with whom I had had some discussions by emails), I think that, regardless of their objections (hollers, really speaking!), my main thesis still does hold. It’s they who don’t understand the quantum theory—and let me hasten to add that by the words “quantum theory,” here I emphatically mean the mainstream quantum theory.

It is the mainstream QM which they themselves don’t understood as well as they should. What my new approach then does is to merely uncover some of these weaknesses, that’s all. … Their weakness pertains to a lack of understanding of the $3D \Leftrightarrow 3ND$ correspondence in general, for any kind of physics: classical or quantum. … Why, I even doubt whether they understand even just the classical vibrations themselves right or not—coupled vibrations under variable potentials, that is—to the extent and depth to which they should.

In short, it is now easy for me to leave their skepticism alone, because I can now clearly see where they failed to get the physics right.

5. Next action-item:

In the near future, I would like to make short trips to some Institutes nearby (viz., in no particular order, one or more of the following: IIT Bombay, IISER Pune, IUCAA Pune, and TIFR Mumbai). I would like to have some face-to-face discussions with physicists on this one single topic: the interaction term in the Hamiltonian for the helium atom. The discussions will be held strictly in the context that is common to us, i.e., in reference to the higher-dimensional Hilbert space of the mainstream QM.

In case no one from these Institutes responds to my requests, I plan to go and see the heads of these Institutes (i.e. Deans and Directors)—in person, if necessary. I might also undertake other action items. However, I also sincerely hope and think that such things would not at all be necessary. There is a reason why I think so. Professors may or may not respond to an outsider’s emails, but they do entertain you if you just show up in their cabin—and if you yourself are smart, courteous, direct, and well… also experienced enough. And if you are capable of holding discussions on the “common” grounds alone, viz. in terms of the linear, mainstream QM as formulated in the higher-dimensional spaces (I gather it’s John von Neumann’s formulation), that is to say, the “Copenhagen interpretation.” (After doing all my studies—and, crucially, after the development of what to me is a satisfactory new approach—I now find that I no longer am as against the Copenhagen interpretation as some of the physicists seem to be.) … All in all, I do hope and think that seeing Diro’s and all won’t be necessary.

I also equally sincerely hope that my approach comes out unscathed during / after these discussions. … Though the discussions externally would be held in terms of mainstream QM, I would also be simultaneously running a second movie of my approach, in my mind alone, cross-checking whether it holds or not. (No, they wouldn’t even suspect that I was doing precisely that.)

I will be able to undertake editing of the Outline document (or leaving it as is and issuing a fresh document) only after these discussions.

6. The bottom-line:

The bottom-line is that my main conceptual development regarding QM is more or less over now, though further developments, discussions, simulations, paper-writing and all can always go on forever—there is never an end to it.

7. Data Science!

So, I now declare that I am free to turn my main focus to the other thing that interests me, viz., Data Science.

I already have a few projects in mind, and would like to initiate work on them right away. One of the “projects” I would like to undertake in the near future is: writing very brief notes, written mainly for myself, regarding the mathematical techniques used in data science. Another one is regarding applying ML techniques to NDT (nondestructive testing). Stay tuned.

A song I like:

(Western, instrumental) “Lara’s theme” (Doctor Zhivago)
Composer: Maurice Jarre

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# Work Is Punishment

Work is not worship—they said.

It’s a punishment, full stop!—they said.

One that is to be smilingly borne.

And so lose everything else too. …

Hmmm… I said. … I was confused.

Work is enjoyment, actually. … I then discovered.

I told them.

They didn’t believe.

Not when I said it.

Not because they ceased believing in me.

It’s just that. They. Simply. Didn’t. Believe. In. It.

And they professed to believe in

a lot of things that never did make

any sense to themselves.

They said so.

And it was so.

A long many years have passed by, since then.

Now, whether they believe in it or not,

I have come to believe in this gem:

Work is punishment—full stop.

That’s the principle on the basis of which I am henceforth going to operate.

And yes! This still is a poem alright?

[What do you think most poems written these days are like?]

It remains a poem.

And I am going to make money. A handsome amount of money.

For once in my life-time.

After all, one can make money and still also write poems.

That’s what they say.

Or do science. Real science. Physics. Even physics for that matter.

Or, work. Real work, too.

It’s better than having no money and…

.

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# Should I give up on QM?

After further and deeper studies of the Schrodinger formalism, I have now come to understand the exact position from which the physicists must be coming (I mean the couple of physicists with who I discussed the ideas of my new approach, as mentioned here [^])—why they must be raising their objections. I came to really understand their positions only now. Here is how it happened.

I was pursuing finding correspondence between the $3ND$ configuration space of the Schrodinger formalism on the one hand and the $3D$ physical space on the other, when I run into this subtle point which made everything look completely different. That point is the following:

Textbooks (or lecture notes, or lecturers) don’t ever highlight this point (in fact, indirectly, they actually obfuscate it), but I came to realize that even in the $1D$ cases like the QM harmonic oscillator (QHO), the Schrodinger formalism itself remains defined only on an abstract hyperspace—it’s just that in the case of the QHO, this hyperspace happens to be $1D$ in nature, that’s all.

I came to realize that, even in the simplest $1D$ case like the QHO the $x$ variable which appears in the Schrodinger equation does not directly refer to the physical space. In case of QHO, it refers to the change in the equilibrium separation between the centers of the two atoms.

Physicists and textbooks don’t mention this point, and in fact, the way they present QM, they make it look as if $x$ is the simple position variable. But in reality, no it is not. It can be made to look like a position variable (and not a change-in-the-interatomic-distance variable) by fixing the coordinate system to one of the two atoms (i.e. by making it a moving or Lagrangian coordinate system). But doing so leads to losing the symmetry in the motion of the two atoms, and more important, it further results in an obfuscation of the real nature of the issue. Mind you, textbook authors are trying to be helpful here. But unwittingly, they end up actually obfuscating the real story.

So, the $x$ variable whose Laplacian you take for the kinetic energy term also does not represent the physical space—not even in the simplest $1D$ cases like the QHO.

This insight, which I gained only now, has made me realize that I need to rethink through the whole thing once again.

In other words, my understanding of QM turned out to have been faulty—though the fault is much more on the part of the textbook authors (and lecturers) than on the part of someone like me—one who has learnt QM only through self-studies.

One implication of this better understanding now is that the new approach as stated in the Outline document isn’t going to work out. Even if there are a lot of good ideas in it (Only the Coulomb potentials, the specific nonlinearity proposed in the potential energy term, the ideas concerning measurements, etc.), there are several other ideas in that document which are just so weak that I will have to completely revise my entire approach once again.

Can I do that—take up a complete rethinking once again, and still hope to succeed?

Frankly, I don’t know. Not at this point of time anyway.

I still have not given up. But a sense of tiredness has crept in now. It now seems possible—very easily possible—that QM will end up defeating me, too.

But before outright leaving the fight, I would like to give it just one more try. One last try.

So, I have decided that I will “work” on this issue for just a little while more. May be a couple of weeks or so. Say until the month-end (March 2019-end). Unless I make some clearing, some breaththrough, I will not pursue QM beyond this time-frame.

What is going to be my strategy?

The only way an enterprise like mine can work out is if the connection between the $3D$ world of observations and the hyperspace formalism can be put in some kind of a valid conceptual correspondence. (That is to say, not just the measurement postulate but something deeper than that, something right at the level of the basic conceptual correspondence itself).

The only strategy that I will now pursue (before giving up on QM) is this: The Schrodinger formalism is based on the higher-dimensional configuration space not because a physicist like him would go specifically hunting for a higher-dimensional space, but primarily because the formulation of Schrodinger’s theory is based on the ideas from the energetics program, viz., the Leibniz-Lagrange-Euler-Hamilton program, their line(s) of thought.

The one possible opening I can think of as of today is this: The energetics program necessarily implies hyperspaces. However, at least in the classical mechanics, there always is a $1:1$ correspondence between such hyperspaces on the one hand and the $3D$ space on the other. Why should QM be any different? … As far as I am concerned, all the mystification they effected for QM over all these decades still does not supply any reason to believe that QM should necessarily be very different. After all, QM does make predictions about real world as described in $3D$! Why, even the position vectors that go into the potential energy operator $\hat{V}$ are defined only in the $3D$ space. …

… So, naturally, it seems that I just have to understand the nature of the correspondence between the Lagrangian mechanics and the $3D$ mechanics better. There must be some opening in there, based on this idea. In fact my suspicion is stronger: If at all there is a real opening to be found, if at all there is any real way to crack this nutty problem, then its key has to be lying somewhere in this correspondence.

So, I have decided to work on seeing if pursuing this line of thought yields something definitive or not. If it doesn’t, right within the next couple of weeks or so, I think I better throw in the towel and declare defeat.

Now, understanding the energetics program better meant opening up once again the books. But given my style, you know, it couldn’t possibly be the maths books—but only the conceptual ones.

So, this morning, I spent some time opening a couple of the movers-and-packers boxes (in which stuff was still lying as I mentioned before [^]), and also made some space in my room (somehow) by shoving the boxes a bit away to open the wall-cupboard, and brought out a few books I wanted to read  / browse through. Here they are.

The one shown opened is what I had mentioned as “the energetics book” in the background material document (see this link [^] in this post [^]). I am going to begin my last shot at QM—the understanding of the $3ND$$3D$ issue, starting with this book. The others may or may not be helpful, but I wanted to boast that they are just a part of personal library too!

Wish me luck!

(And suggest me a job in Data Science all the same! [Not having a job is the only thing that gets me (really) angry these days—and it does. So there.])

BTW, I really LOL on the Record of 17 off 71. (Just think what happened in 204!)

A song I like:

(Hindi) “O mere dil ke chain…”
Singer: Kishor Kumar
Music: R. D. Burman
Lyrics: Majrooh Sultanpuri

Minor editing to be done and a song to be added, tomorrow. But feel free to read the post right starting today.

Song added on 2019.03.10 12.09 AM IST. Subject to change if I have run it already.

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# An update on my research

28th February is the National Science Day in India.

The story goes that it was on this day (in 1928) that C. V. Raman discovered the effect known by his name.

I don’t believe that great discoveries like that are made in just one single day. There is a whole sequence of many crucially important days involved in them.

Yes, on this day, Raman might have achieved a certain milestone or made a key finding regarding his discovery. However, even if true in this case (which I very much doubt), it’s not true in general. Great discoveries are not made in a single day; they are usually spread over much longer span of time. A particular instant or a day has more of just a symbolic value—no matter how sudden the discovery might have looked to someone, including to the discoverer.

There of course was a distinguished moment when Kekule, in his famous dream, saw a snake swallowing its own tail. However, therefore to say that he made the discovery concerning the ring structure of the benzene molecule, just in a single moment, or in a single flash of imagination, is quite a bit of a stretch.

Try it out yourself. Think of a one-line statement that encapsulates the findings of a discovery made by a single man. Compare it with another statement which encapsulates any of the previous views regarding the same matter (i.e., before this discovery came along). This way, you can isolate the contributions of a single individual. Then analyze those contributions. You would invariably find that there are several different bits of progress that the discovery connected together, and these bits themselves (i.e., the contributions made individually by the discoverer himself) were not all discovered on the same day. Even if a day or an hour is truly distinctive in terms of the extent of progress made, it invariably has the character of taking an already ongoing process to a state of completion—but not of conducting that entire process. Mystical revelation is never a good metaphor to employ in any context—not even in the spiritual matters, let alone in the scientific ones.

Anyway, it’s nice that they didn’t choose Raman’s birth-day for this Day, but instead chose a day that was related to his most famous work in science. Good sense! And easy to remember too: 28-02-’28.

Let me celebrate this year’s Science Day in my own, small, personal way. Let me note down a bit of an update on my research.

1. I have had a bit of a correspondence, regarding my new approach, with a couple of physicists. Several objections were made by them, but to cut a long story short, neither seemed to know how to get into that mode kind of thinking which most naturally leads to my main thesis, and hence helps understand it.

The typical thought process both these physicists displayed was the one which is required in finding analytical solutions of problems of a certain kind, using an analysis of a specific kind. But it is not the kind of thought process which is typically required in the computational modeling of complex phenomena. Let me remind you that my theory is nonlinear in nature. Nonlinearity, in particular, is best approached only computationally—you would be hopelessly out of your wits if you try to find analytical solutions to a nonlinear system. What you should instead pursue is: thinking in terms of the following ingredients: certain objects, an algorithm to manipulate their states, and tracing the run-time evolution of the system. You try this algorithmic way of thinking, and the whole thing (I mean understanding the nature of a nonlinear system) becomes easy. Otherwise, it looks hopelessly complicated, incomprehensible, and therefore, deeply suspicious, if not outright wrong. Both the physicists with who I interacted seemed to be thinking in terms of the linear theory of QM, thereby restricting their thought modes to only the traditional formalism based on the abstract Hilbert-spaces and linear Hermitian operators. Uh oh! Not good. QM is fundamentally nonlinear; the linear formulations of QM are merely approximations to its true nature. No matter how analytically rigorous you can get in the traditional QM, it’s not going to help you understand the true nature of quantum phenomena, simply because a linear system is incapable of throwing much light on the nonlinear system of which it is an approximation.

I believe it was out of this reason—their continuing to think in terms of linear systems defined over hyperspaces and the operator algebra—that one of them raised the objection that if $\Psi$ in MSQM (mainstream QM) is defined on a $3ND$ configuration space, how come my $\Psi(x,t)$ could be defined over the physical $3D$ space. He didn’t realize, even after I supplied the example of the classical $N$-particle molecular dynamics (MD) simulations, that using an abstract higher-dimensional space isn’t the only viable manner in which you can capture the physics of a situation. (And I had indicated right in the Outline document too, that you first try to understand how a Newtonian evolution would work for multiple, charged, point-particles as in classical physics, and only then modify this evolution by introducing the system wavefunction.)

I came to gather that apparently, some people (who follow the Bohmian mechanics doctrine) have tried to find a $3ND \leftrightarrow 3D$ correspondence for a decade, if not more. Apparently, they didn’t succeed. I wonder why, because doing so should be so damn straight-forward (even if it would not be easy). You only have to realize that a configuration space refers to all possible configurations, whereas what an evolution over a $3D$ physical space directly deals with is only one initial configuration at a time. That is what specifying the ICs and the BCs does for you.

In case of MD simulations, you don’t define a function over the entire $3ND$ configuration space in the first place. You don’t try to produce an evolution equation which relies on only those kinds of operators which modify all parts of the entire hyperspace-function in one shot, simultaneously. Since you don’t think in such hyperspace terms in the first place, you also don’t have to think in terms of the projection operators bringing the system dynamics down to $3D$ in particular cases either. You don’t do that in the context of MD simulations, and you don’t do it in the context of my approach either.

This physicist also didn’t want me to say something using analogies and metaphors, and so I didn’t mention it to him, but I guess I can use an analogy here. It will allow even a layman to get a sense of the issue right.

This physicist was insisting on having a map of an entire territory, and was more or less completely dismissing my approach on the grounds that I only supply the surveying instruments like the theodolite and the triangulation algorithm. He expected to see the map—even when a theory is at a fledgling stage. He nevertheless was confident that I was wrong because I was insisting that each physical object in the actual territory is only at one place at any given instant, that it is not spread all over the map. This analogy is not exact, but it is helpful: it does bring out the difference of focusing on only the actually followed trajectory in the configuration space, vs. an insistence on using the entirety of the configuration space for any description of an evolution. But that guy didn’t get this point either. And he wanted equations, not analogies or metaphors.

Little wonder they have not been successful in finding out what logical connection there is between the abstract $3ND$ hyperspace on the one hand, and the $3D$ physical space on the other hand. Little wonder they don’t progress despite having worked on the problem for a decade or so (as this guy himself said).

Yeah, physicists, work harder, I say! [LOL!]

2. Apart from it all—I mean all those “discussions”—I have also realized that there are several errors or confusing explanations in the Outline document which I uploaded at iMechanica on 11th February 2019. Of course, these errors are more minor in nature. There are many, many really important ideas in that document which are not in error.

The crucially important and new ideas which are valid include, just to cite a few aspects: (i) my insistence on using only those potentials that are singularly anchored into the point-particle charges, (ii) the particular nonlinearity I have proposed for the system evolution, (iii) the idea that during a measurement it is the Instrument whose state undergoes a cascade of bifurcations or catastrophic changes, whereas the System state essentially remains the same (that there is no wavefunction collapse). And, many, many other ideas too. These ideas are not only crucial to my approach but they also are absolutely new and original. (Yes, you can be confident about this part, too—else, Americans would have pointed out the existing precedence by now. (They are just looking to find errors in what(ever) I say.)) All these ideas do remain intact. The confusing part or the one having erroneous statements indeed is more minor. It concerns more with how I tried to explain things. And I am working on removing these errors too.

I have also come to realize that I need to explicitly give a set of governing equations, as well as describe the algorithm that could be used in building the simulations. Yes, the physicist had asked me for an evolution equation. I thought that any one, given the Schrodinger equation and my further verbal additions / modifications to it, could easily “get” it. But apparently, he could not. So, yes, I will explicitly write down the evolution equation for my approach, as an equation that is separate from Schrodinger’s. In the next revision of the document (or addition to it) I will not rely on the only implicitly understood constraints or modifications to the TDSE.

3. There also are some other issues which I noticed entirely on my own, and I am working on them.

One such issue concerns the way the kinetic energy is captured in the MSQM vs. how my approach ought to handle and capture it.

In MSQM, the kinetic energy consists of a sum of 1-particle Laplacian operators that refer to particle coordinates. Given the fact that my approach has the wavefunction defined over the $3D$ space, how should this aspect be handled? … By the time I wrote my Outline document (version 11 February 2019), I had not thought a lot about the kinetic energy part. Now, I found out, I have to think really deep about it. May be, I will have to abandon the form of Schrodinger’s equation itself to a further extent. Of course, the energy analysis will progress on the same lines (total energy = kinetic + potential), and the de Broglie relations will have to be honored. But the form of the equation may turn out to be a bit different.

You see, what MSQM does is to represent the particles using only the $\Psi(x,t)$ field. The potential energy sure can be constructed in reference to a set of discrete particle positions even in MSQM, but what the $\hat{V}$ operator then yields is just a single number. (In case of time-dependent potentials, the value of this variable varies in time.) The multiplication by the hyperspace-function $\Psi(x,t)$ then serves to distribute this much amount of energy (that single number) over the entire hyperspace. Now realize that $|\Psi(x,t)|^2$ gives the probability. So, in a way, indirectly, even if you can calculate / compute the potential energy of the system starting from a certain set of particle positions, in the MSQM, you then have to immediately abandon them—the idea of the discrete particles. The MSQM formalism doesn’t need it—the particle positions. You deal only with the hyperspace-occupying $\Psi(x,t)$. The formulation of kinetic energy also refers to only the $\Psi(x,t)$ field. Thus, in MSQM, particles are ultimately represented only via the $\Psi(x,t)$ field. The $\Psi(x,t)$ is the particles.

In contrast, in my approach, the particles are represented directly as point-phenomena, and their positions remain significant throughout. The $\Psi(x,t)$ field of my approach connects, and causally interacts with, the particles. But it does not represent the particles. Ontologically, $\Psi(x,t)$ is basically different from particles, even if the background object does interacts with the particles. Naturally, why should I represent their kinetic energies via the Laplacian terms? … Got the idea? The single number that is the kinetic energy of the particles, need not be regarded as being distributed over the $3D$ space at all, in my approach. But in 11th February version of the Outline document, I did say that the governing equation is only Schrodinger’s. The modifications required to be made to the TDSE on account of the kinetic energy term, is something I had not even thought of, because in writing that version, I was trying focusing on getting as many details regarding the potential energy out as possible. After all, the nonlinear nature of QM occurs due to the potential term, doesn’t it?

So, I need to get issues like these straightened out too.

… All in all, I guess I can say that I am more or less (but not completely) done with the development concerning the spin-less 1-particle systems, esp. the time-independent states. So far, it seems that my approach does work fine with them. Of course, new issues continue to strike me all the time, and I continue finding answers to them as well—as happens in any approach that is completely new. New, right from the stage of the very basic ideation  concerning what kind of objects there should be, in the theory.

I have just about begun looking into the (spin-less) multi-particle states. That is the natural order in which the theory should progress, and my work is tracing just this same path. But as I said, I might also be revising some parts of the earlier presented theory, as and when necessary.

4. I also realized on my own, but only after the interaction with the physicists was already over, that actually, I need not wait for the entire multi-particle theory to get developed before beginning with simulations. In fact, it should be possible to handle some simple 1-particle $1D$ cases like the particle in a box or the QHO (quantum-mechanical oscillator) right away.

I plan to pursue these simulations right in the near future. However, I will not be able to complete pursuing all their aspects in the near future—not even in the simple cases involving just $1D$ simulations. I plan to do a preliminary simulation or two, and then suspend this activity until the time that I land a well-paying job in data science in Pune.

No songs section this time because I happened to post several entries almost back to back here, and in the process, I seem to have used up all the songs that were both new (not run here before) and also on the top of my mind. … May be I will return later and add a song if one strikes me easily.

Bye for now, and have a happy Science Day!

Minor editing may be done later today. Done by 20:15 hrs the same day.

/

# Python scripts for simulating QM, part 0: A general update

My proposed paper on my new approach to QM was not accepted at the international conference where I had sent my abstract. (For context, see the post before the last, here [^] ).

“Thank God,” that’s what I actually felt when I received this piece of news, “I can now immediately proceed to procrastinate on writing the full-length paper, and also, simultaneously, un-procrastinate on writing some programs in Python.”

So far, I have written several small and simple code-snippets. All of these were for the usual (text-book) cases; all in only $1D$. Here in this post, I will mention specifically which ones…

Time-independent Schrodinger equation (TISE):

Here, I’ve implemented a couple of scripts, one for finding the eigen-vectors and -values for a particle in a box (with both zero and arbitrarily specified potentials) and another one for the quantum simple harmonic oscillator.

These were written not with the shooting method (which is the method used in the article by Rhett Allain for the Wired magazine [^]) but with the matrix method. … Yes, I have gone past the stage of writing all the numerical analysis algorithm in original, all by myself. These days, I directly use Python libraries wherever available, e.g., NumPy’s LinAlg methods. That’s why, I preferred the matrix method. … My code was not written from scratch; it was based on Cooper’s code “qp_se_matrix”, here [PDF ^]).

Time-dependent Schrodinger equation (TDSE):

Here, I tried out a couple of scripts.

The first one was more or less a straightforward porting of Ian Cooper’s program “se_fdtd” [PDF ^] from the original MatLab to Python. The second one was James Nagel’s Python program (written in 2007 (!) and hosted as a SciPy CookBook tutorial, here [^]). Both follow essentially the same scheme.

Initially, I found this scheme to be a bit odd to follow. Here is what it does.

It starts out by replacing the complex-valued Schrodinger equation with a pair of real-valued (time-dependent) equations. That was perfectly OK by me. It was their discretization which I found to be a bit peculiar. The discretization scheme here is second-order in both space and time, and yet it involves explicit time-stepping. That’s peculiar, so let me write a detailed note below (in part, for my own reference later on).

Also note: Though both Cooper and Nagel implement essentially the same method, Nagel’s program is written in Python, and so, it is easier to discuss (because the array-indexing is 0-based). For this reason, I might make a direct reference only to Nagel’s program even though it is to be understood that the same scheme is found implemented also by Cooper.

A note on the method implemented by Nagel (and also by Cooper):

What happens here is that like the usual Crank-Nicolson (CN) algorithm for the diffusion equation, this scheme too puts the half-integer time-steps to use (so as to have a second-order approximation for the first-order derivative, that of time). However, in the present scheme, the half-integer time-steps turn out to be not entirely fictitious (the way they are, in the usual CN method for the single real-valued diffusion equation). Instead, all of the half-integer instants are fully real here in the sense that they do enter the final discretized equations for the time-stepping.

The way that comes to happen is this: There are two real-valued equations to solve here, coupled to each other—one each for the real and imaginary parts. Since both the equations have to be solved at each time-step, what this method does is to take advantage of that already existing splitting of the time-step, and implements a scheme that is staggered in time. (Note, this scheme is not staggered in space, as in the usual CFD codes; it is staggered only in time.) Thus, since it is staggered and explicit, even the finite-difference quantities that are defined only at the half-integer time-steps, also get directly involved in the calculations. How precisely does that happen?

The scheme defines, allocates memory storage for, and computationally evaluates the equation for the real part, but this computation occurs only at the full-integer instants ($n = 0, 1, 2, \dots$). Similarly, this scheme also defines, allocates memory for, and computationally evaluates the equation for the imaginary part; however, this computation occurs only at the half-integer instants ($n = 1/2, 1+1/2, 2+1/2, \dots$). The particulars are as follows:

The initial condition (IC) being specified is, in general, complex-valued. The real part of this IC is set into a space-wide array defined for the instant $n$; here, $n = 0$. Then, the imaginary part of the same IC is set into a separate array which is defined nominally for a different instant: $n+1/2$. Thus, even if both parts of the IC are specified at $t = 0$, the numerical procedure treats the imaginary part as if it was set into the system only at the instant $n = 1/2$.

Given this initial set-up, the actual time-evolution proceeds as follows:

• The real-part already available at $n$ is used in evaluating the “future” imaginary part—the one at $n+1/2$
• The imaginary part thus found at $n+1/2$ is used, in turn, for evaluating the “future” real part—the one at $n+1$.

At this point that you are allowed to say: lather, wash, repeat… Figure out exactly how. In particular, notice how the simulation must proceed in integer number of pairs of computational steps; how the imaginary part is only nominally (i.e. only computationally) distant in time from its corresponding real part.

Thus, overall, the discretization of the space part is pretty straight-forward here: the second-order derivative (the Laplacian) is replaced by the usual second-order finite difference approximation. However, for the time-part, what this scheme does is both similar to, and different from, the usual Crank-Nicolson scheme.

Like the CN scheme, the present scheme also uses the half-integer time-levels, and thus manages to become a second-order scheme for the time-axis too (not just space), even if the actual time interval for each time-step remains, exactly as in the CN, only $\Delta t$, not $2\Delta t$.

However, unlike the CN scheme, this scheme still remains explicit. That’s right. No matrix equation is being solved at any time-step. You just zip through the update equations.

Naturally, the zipping through comes with a “cost”: The very scheme itself comes equipped with a stability criterion; it is not unconditionally stable (the way CN is). In fact, the stability criterion now refers to half of the time-interval, not full, and thus, it is a bit even more restrictive as to how big the time-step ($\Delta t$) can be given a certain granularity of the space-discretization ($\Delta x$). … I don’t know, but guess that this is how they handle the first-order time derivatives in the FDTD method (finite difference time domain). May be the physics of their problems itself is such that they can get away with coarser grids without being physically too inaccurate, who knows…

Other aspects of the codes by Nagel and Cooper:

For the initial condition, both Cooper and Nagel begin with a “pulse” of a cosine function that is modulated to have the envelop of the Gaussian. In both their codes, the pulse is placed in the middle, and they both terminate the simulation when it reaches an end of the finite domain. I didn’t like this aspect of an arbitrary termination of the simulation.

However, I am still learning the ropes for numerically handling the complex-valued Schrodinger equation. In any case, I am not sure if I’ve got good enough a handle on the FDTD-like aspects of it. In particular, as of now, I am left wondering:

What if I have a second-order scheme for the first-order derivative of time, but if it comes with only fictitious half-integer time-steps (the way it does, in the usual Crank-Nicolson method for the real-valued diffusion equation)? In other words: What if I continue to have a second-order scheme for time, and yet, my scheme does not use leap-frogging? In still other words: What if I define both the real and imaginary parts at the same integer time-steps $n = 0, 1, 2, 3, \dots$ so that, in both cases, their values at the instant $n$ are directly fed into both their values at $n+1$?

In a way, this scheme seems simpler, in that no leap-frogging is involved. However, notice that it would also be an implicit scheme. I would have to solve two matrix-equations at each time-step. But then, I could perhaps get away with a larger time-step than what Nagel or Cooper use. What do you think? Is checker-board patterning (the main reason why we at all use staggered grids in CFD) an issue here—in time evolution? But isn’t the unconditional stability too good to leave aside without even trying? And isn’t the time-axis just one-way (unlike the space-axis that has BCs at both ends)? … I don’t know…

PBCs and ABCs:

Even as I was (and am) still grappling with the above-mentioned issue, I also wanted to make some immediate progress on the front of not having to terminate the simulation (once the pulse reached one of the ends of the domain).

So, instead of working right from the beginning with a (literally) complex Schrodinger equation, I decided to first model the simple (real-valued) diffusion equation, and to implement the PBCs (periodic boundary conditions) for it. I did.

My code seems to work, because the integral of the dependent variable (i.e., the total quantity of the diffusing quantity present in the entire domain—one with the topology of a ring) does seem to stay constant—as is promised by the Crank-Nicolson scheme. The integral stays “numerically the same” (within a small tolerance) even if obviously, there are now fluxes at both the ends. (An initial condition of a symmetrical saw-tooth profile defined between $y = 0.0$ and $y = 1.0$, does come to asymptotically approach the horizontal straight-line at $y = 0.5$. That is what happens at run-time, so obviously, the scheme seems to handle the fluxes right.)

Anyway, I don’t always write everything from the scratch; I am a great believer in lifting codes already written by others (with attribution, of course :)). Thus, while thus searching on the ‘net for some already existing resources on numerically modeling the Schrodinger equation (preferably with code!), I also ran into some papers on the simulation of SE using ABCs (i.e., the absorbing boundary conditions). I was not sure, however, if I should implement the ABCs immediately…

As of today, I think that I am going to try and graduate from the transient diffusion equation (with the CN scheme and PBCs), to a trial of the implicit TDSE without leap-frogging, as outlined above. The only question is whether I should throw in the PBCs to go with that or the ABCs. Or, may be, neither, and just keep pinning the  $\Psi$ values for the end- and ghost-nodes down to $0$, thereby effectively putting the entire simulation inside an infinite box?

At this point of time, I am tempted to try out the last. Thus, I think that I would rather first explore the staggering vs. non-staggering issue for a pulse in an infinite box, and understand it better, before proceeding to implement either the PBCs or the ABCs. Of course, I still have to think more about it… But hey, as I said, I am now in a mood of implementing, not of contemplating.

Why not upload the programs right away?

BTW, all these programs (TISE with matrix method, TDSE on the lines of Nagel/Cooper’s codes, transient DE with PBCs, etc.) are still in a fluid state, and so, I am not going to post them immediately here (though over a period of time, I sure would).

The reason for not posting the code runs something like this: Sometimes, I use the Python range objects for indexing. (I saw this goodie in Nagel’s code.) At other times, I don’t. But even when I don’t use the range objects, I anyway am tempted to revise the code so as to have them (for a better run-time efficiency).

Similarly, for the CN method, when it comes to solving the matrix equation at each time-step, I am still not using the TDMA (the Thomas algorithm) or even just sparse matrices. Instead, right now, I am allocating the entire $N \times N$ sized matrices, and am directly using NumPy’s LinAlg’s solve() function on these biggies. No, the computational load doesn’t show up; after all, I anyway have to use a 0.1 second pause in between the rendering passes, and the biggest matrices I tried were only $1001 \times 1001$ in size. (Remember, this is just a $1D$ simulation.) Even then, I am tempted a bit to improve the efficiency. For these and similar reasons, some or the other tweaking is still going on in all the programs. That’s why, I won’t be uploading them right away.

Anything else about my new approach, like delivering a seminar or so? Any news from the Indian physicists?

I had already contacted a couple of physics professors from India, both from Pune: one, about 1.5 years ago, and another, within the last 6 months. Both these times, I offered to become a co-guide for some computational physics projects to be done by their PG/UG students or so. Both times (what else?) there was absolutely no reply to my emails. … If they were to respond, we could have together progressed further on simulating my approach. … I have always been “open” about it.

The above-mentioned experience is precisely similar to how there have been no replies when I wrote to some other professors of physics, i.e., when I offered to conduct a seminar (covering my new approach) in their departments. Particularly, from the young IISER Pune professor whom I had written. … Oh yes, BTW, there has been one more physicist who I contacted recently for a seminar (within the last month). Once again, there has been no reply. (This professor is known to enjoy hospitality abroad as an Indian, and also use my taxpayer’s money for research while in India.)

No, the issue is not whether the emails I write using my Yahoo! account go into their span folder—or something like that. That would be too innocuous a cause, and too easy to deal with—every one has a mobile-phone these days. But I know these (Indian) physicists. Their behaviour remains exactly the same even if I write my emails using a respectable academic email ID (my employers’, complete with a .edu domain). This was my experience in 2016, and it repeated again in 2017.

The bottom-line is this: If you are an engineer and if you write to these Indian physicists, there is almost a guarantee that your emails will go into a black-hole. They will not reply to you even if you yourself have a PhD, and are a Full Professor of engineering (even if only on an ad-hoc basis), and have studied and worked abroad, and even if your blog is followed internationally. So long as you are engineer, and mention QM, the Indian physicists simply shut themselves off.

However, there is a trick to get them to reply you. Their behavior does temporarily change when you put some impressive guy in your cc-field (e.g., some professor friend of yours from some IIT). In this case, they sometimes do reply your first email. However, soon after that initial shaking of hands, they somehow go back to their true core; they shut themselves off.

And this is what invariably happens with all of them—no matter what other Indian bloggers might have led you to believe.

There must be some systemic reasons for such behavior, you say? Here, I will offer a couple of relevant observations.

Systemically speaking, Indian physicists, taken as a group (and leaving any possible rarest of the rare exceptions aside), all fall into one band: (i) The first commonality is that they all are government employees. (ii) The second commonality they all tend to be leftists (or, heavily leftists). (iii) The third commonality is they (by and large) share is that they had lower (or far lower) competitive scores in the entrance examinations at the gateway points like XII, GATE/JAM, etc.

The first factor typically means that they know that no one is going to ask them why they didn’t reply (even to people like with my background). The second factor typically means that they don’t want to give you any mileage, not even just a plain academic respect, if you are not already one of “them”. The third factor typically means that they simply don’t have the very intellectual means to understand or judge anything you say if it is original—i.e., if it is not based on some work of someone from abroad. In plain words: they are incompetent. (That in part is the reason whenever I run into a competent Indian physicist, it is both a surprise and a pleasure. To drop a couple of names: Prof. Kanhere (now retired) from UoP (now SPPU), and Prof. Waghmare of JNCASR. … But leaving aside this minuscule minority, and coming to the rest of the herd: the less said, the better.)

In short, Indian physicists all fall into a band. And they all are very classical—no tunneling is possible. Not with these Indian physicists. (The trends, I guess, are similar all over the world. Yet, I definitely can say that Indians are worse, far worse, than people from the advanced, Western, countries.)

Anyway, as far as the path through the simulations goes, since no help is going to come from these government servants (regarded as physicists by foreigners), I now realized that I have to get going about it—simulations for my new approach—entirely on my own. If necessary, from the basic of the basics. … And that’s how I got going with these programs.

Are these programs going to provide a peek into my new approach?

No, none of these programs I talked about in this post is going to be very directly helpful for simulations related to my new approach. The programs I wrote thus far are all very, very standard (simplest UG text-book level) stuff. If resolving QM riddles were that easy, any number of people would have done it already.

… So, the programs I wrote over the last couple of weeks are nothing but just a beginning. I have to cover a lot of distance. It may take months, perhaps even a year or so. But I intend to keep working at it. At least in an off and on manner. I have no choice.

And, at least currently, I am going about it at a fairly good speed.

For the same reason, expect no further blogging for another 2–3 weeks or so.

But one thing is for certain. As soon as my paper on my new approach (to be written after running the simulations) gets written, I am going to quit QM. The field does not hold any further interest to me.

Coming to you: If you still wish to know more about my new approach before the paper gets written, then you convince these Indian professors of physics to arrange for my seminar. Or, else…

… What else? Simple! You. Just. Wait.

[Or see me in person if you would be visiting India. As I said, I have always been “open” from my side, and I continue to remain so.]

A song I like:
(Hindi) “bheegee bheegee fizaa…”
Music: Hemant Kumar
Singer: Asha Bhosale
Lyrics: Kaifi Aazmi

History:
Originally published: 2018.11.26 18:12 IST
Extension and revision: 2018.11.27 19.29 IST

# A list of books for understanding the non-relativistic QM

TL;DR: NFY (Not for you).

In this post, I will list those books which have been actually helpful to me during my self-studies of QM.

But before coming to the list, let me first note down a few points which would be important for engineers who wish to study QM on their own. After all, my blog is regularly visited by engineers too. That’s what the data about the visit patterns to various posts says.

Others (e.g. physicists) may perhaps skip over the note in the next section, and instead jump directly over to the list itself. However, even if the note for engineers is too long, perhaps, physicists should go through it too. If they did, they sure would come to know a bit more about the kind of background from which the engineers come.

# I. A note for engineers who wish to study QM on their own:

The point is this: QM is vast, even if its postulates are just a few. So, it takes a prolonged, sustained effort to learn it.

For the same reason (of vastness), learning QM also involves your having to side-by-side learn an entirely new approach to learning itself. (If you have been a good student of engineering, chances are pretty good that you already have some first-hand idea about this meta-learning thing. But the point is, if you wish to understand QM, you have to put it to use once again afresh!)

In terms of vastness, QM is, in some sense, comparable to this cluster of subjects spanning engineering and physics: engineering thermodynamics, statistical mechanics, kinetics, fluid mechanics, and heat- and mass-transfer.

I.1 Thermodynamics as a science that is hard to get right:

The four laws of thermodynamics (including the zeroth and the third) are easy enough to grasp—I mean, in the simpler settings. But when it comes to this subject (as also for the Newtonian mechanics, i.e., from the particle to the continuum mechanics), God lies not in the postulates but in their applications.

The statement of the first law of thermodynamics remains the same simple one. But complexity begins to creep in as soon as you begin to dig just a little bit deeper with it. Entire categories of new considerations enter the picture, and the meaning of the same postulates gets both enriched and deepened with them. For instance, consider the distinction of the open vs. the closed vs. the isolated systems, and the corresponding changes that have to be made even to the mathematical statements of the law. That’s just for the starters. The complexity keeps increasing: studies of different processes like adiabatic vs. isochoric vs. polytropic vs. isentropic etc., and understanding the nature of these idealizations and their relevance in diverse practical applications such as: steam power (important even today, specifically, in the nuclear power plants), IC engines, jet turbines, refrigeration and air-conditioning, furnaces, boilers, process equipment, etc.; phase transitions, material properties and their variations; empirical charts….

Then there is another point. To really understand thermodynamics well, you have to learn a lot of other subjects too. You have to go further and study some different but complementary sciences like heat and mass transfer, to begin with. And to do that well, you need to study fluid dynamics first. Kinetics is practically important too; think of process engineering and cost of energy. Ideas from statistical mechanics are important from the viewpoint of developing a fundamental understanding. And then, you have to augment all this study with all the empirical studies of the irreversible processes (think: the boiling heat transfer process). It’s only when you study such an entire gamut of topics and subjects that you can truly come to say that you now have some realistic understanding of the subject matter that is thermodynamics.

Developing understanding of the aforementioned vast cluster of subjects (of thermal sciences) is difficult; it requires a sustained effort spanning over years. Mistakes are not only very easily possible; in engineering schools, they are routine. Let me illustrate this point with just one example from thermodynamics.

Consider some point that is somewhat nutty to get right. For instance, consider the fact that no work is done during the free expansion of a gas. If you are such a genius that you could correctly get this point right on your very first reading, then hats off to you. Personally, I could not. Neither do I know of even a single engineer who could. We all had summarily stumbled on some fine points like this.

You see, what happens here is that thermodynamics and statistical mechanics involve entirely different ways of thinking, but they both are being introduced almost at the same time during your UG studies. Therefore, it is easy enough to mix up the some disparate metaphors coming from these two entirely different paradigms.

Coming to the specific example of the free expansion, initially, it is easy enough for you to think that since momentum is being carried by all those gas molecules escaping the chamber during the free expansion process, there must be a leakage of work associated with it. Further, since the molecules were already moving in a random manner, there must be an accompanying leakage of the heat too. Both turn out to be wrong ways of thinking about the process! Intuitions about thermodynamics develop only slowly. You think that you understood what the basic idea of a system and an environment is like, but the example of the free expansion serves to expose the holes in your understanding. And then, it’s not just thermo and stat mech. You have to learn how to separate both from kinetics (and they all, from the two other, closely related, thermal sciences: fluid mechanics, and heat and mass transfer).

But before you can learn to separate out the unique perspectives of these subject matters, you first have to learn their contents! But the way the university education happens, you also get exposed to them more or less simultaneously! (4 years is as nothing in a career that might span over 30 to 40 years.)

Since you are learning a lot many different paradigms at the same time, it is easy enough to naively transfer your fledgling understanding of one aspect of one paradigm (say, that of the particle or statistical mechanics) and naively insert it, in an invalid manner, into another paradigm which you are still just learning to use at roughly the same time (thermodynamics). This is what happens in the case of the free expansion of gases. Or, of throttling. Or, of the difference between the two… It is a rare student who can correctly answer all the questions on this topic, during his oral examination.

Now, here is the ultimate point: Postulates-wise, thermodynamics is independent of the rest of the subjects from the aforementioned cluster of subjects. So, in theory, you should be able to “get” thermodynamics—its postulates, in all their generality—even without ever having learnt these other subjects.

Yet, paradoxically enough, we find that complicated concepts and processes also become easier to understand when they are approached using many different conceptual pathways. A good example here would be the concept of entropy.

When you are a XII standard student (or even during your first couple of years in engineering), you are, more or less, just getting your feet wet with the idea of the differentials. As it so happens, before you run into the concept of entropy, virtually every physics concept was such that it was a ratio of two differentials. For instance, the instantaneous velocity is the ratio of d(displacement) over d(time). But the definition of entropy involves a more creative way of using the calculus: it has a differential (and that too an inexact differential), but only in the numerator. The denominator is a “plain-vanilla” variable. You have already learnt the maths used in dealing with the rates of changes—i.e. the calculus. But that doesn’t mean that you have an already learnt physical imagination with you which would let you handle this kind of a definition—one that involves a ratio of a differential quantity to an ordinary variable. … “Why should only one thing change even as the other thing remains steadfastly constant?” you may wonder. “And if it is anyway going to stay constant, then is it even significant? (Isn’t the derivative of a constant the zero?) So, why not just throw the constant variable out of the consideration?” You see, one major reason you can’t deal with the definition of entropy is simply because you can’t deal with the way its maths comes arranged. Understanding entropy in a purely thermodynamic—i.e. continuum—context can get confusing, to say the least. But then, just throw in a simple insight from Boltzmann’s theory, and suddenly, the bulb gets lit up!

So, paradoxically enough, even if multiple paradigms mean more work and even more possibilities of confusion, in some ways, having multiple approaches also does help.

When a subject is vast, and therefore involves multiple paradigms, people regularly fail to get certain complex ideas right. That happens even to very smart people. For instance, consider Maxwell’s daemon. Not many people could figure out how to deal with it correctly, for such a long time.

…All in all, it is only some time later, when you have already studied all these topics—thermodynamics, kinetics, statistical mechanics, fluid mechanics, heat and mass transfer—that finally things begin to fall in place (if they at all do, at any point of time!). But getting there involves hard effort that goes on for years: it involves learning all these topics individually, and then, also integrating them all together.

In other words, there is no short-cut to understanding thermodynamics. It seems easy enough to think that you’ve understood the 4 laws the first time you ran into them. But the huge gaps in your understanding begin to become apparent only when it comes to applying them to a wide variety of situations.

I.2 QM is vast, and requires multiple passes of studies:

Something similar happens also with QM. It too has relatively few postulates (3 to 6 in number, depending on which author you consult) but a vast scope of applicability. It is easy enough to develop a feeling that you have understood the postulates right. But, exactly as in the case of thermodynamics (or Newtonian mechanics), once again, the God lies not in the postulates but rather in their applications. And in case of QM, you have to hasten to add: the God also lies in the very meaning of these postulates—not just their applications. QM carries a one-two punch.

Similar to the case of thermodynamics and the related cluster of subjects, it is not possible to “get” QM in the first go. If you think you did, chances are that you have a superhuman intelligence. Or, far, far more likely, the plain fact of the matter is that you simply didn’t get the subject matter right—not in its full generality. (Which is what typically happens to the CS guys who think that they have mastered QM, even if the only “QM” they ever learnt was that of two-state systems in a finite-dimensional Hilbert space, and without ever acquiring even an inkling of ideas like radiation-matter interactions, transition rates, or the average decoherence times.)

The only way out, the only way that works in properly studying QM is this: Begin studying QM at a simpler level, finish developing as much understanding about its entire scope as possible (as happens in the typical Modern Physics courses), and then come to studying the same set of topics once again in a next iteration, but now to a greater depth. And, you have to keep repeating this process some 4–5 times. Often times, you have to come back from iteration n+2 to n.

As someone remarked at some forum (at Physics StackExchange or Quora or so), to learn QM, you have to give it “multiple passes.” Only then can you succeed understanding it. The idea of multiple passes has several implications. Let me mention only two of them. Both are specific to QM (and not to thermodynamics).

First, you have to develop the art of being able to hold some not-fully-satisfactory islands of understanding, with all the accompanying ambiguities, for extended periods of time (which usually runs into years!). You have to learn how to give a second or a third pass even when some of the things right from the first pass are still nowhere near getting clarified. You have to learn a lot of maths on the fly too. However, if you ask me, that’s a relatively easier task. The really difficult part is that you have to know (or learn!) how to keep forging ahead, even if at the same time, you carry a big set of nagging doubts that no one seems to know (or even care) about. (To make the matters worse, professional physicists, mathematicians and philosophers proudly keep telling you that these doubts will remain just as they are for the rest of your life.) You have to learn how to shove these ambiguous and un-clarified matters to some place near the back of your mind, you have to learn how to ignore them for a while, and still find the mental energy to once again begin right from the beginning, for your next pass: Planck and his cavity radiation, Einstein, blah blah blah blah blah!

Second, for the same reason (i.e. the necessity of multiple passes and the nature of QM), you also have to learn how to unlearn certain half-baked ideas and replace them later on with better ones. For a good example, go through Dan Styer’s paper on misconceptions about QM (listed near the end of this post).

Thus, two seemingly contradictory skills come into the play: You have to learn how to hold ambiguities without letting them affect your studies. At the same time, you also have to learn how not to hold on to them forever, or how to unlearn them, when the time to do becomes ripe.

Thus, learning QM does not involve just learning of new contents. You also have learn this art of building a sufficiently “temporary” but very complex conceptual structure in your mind—a structure that, despite all its complexity, still is resilient. You have to learn the art of holding such a framework together over a period of years, even as some parts of it are still getting replaced in your subsequent passes.

And, you have to compensate for all the failings of your teachers too (who themselves were told, effectively, to “shut up and calculate!”) Properly learning QM is a demanding enterprise.

# II. The list:

Now, with that long a preface, let me come to listing all the main books that I found especially helpful during my various passes. Please remember, I am still learning QM. I still don’t understand the second half of most any UG book on QM. This is a factual statement. I am not ashamed of it. It’s just that the first half itself managed to keep me so busy for so long that I could not come to studying, in an in-depth manner, the second half. (By the second half, I mean things like: the QM of molecules and binding, of their spectra, QM of solids, QM of complicated light-matter interactions, computational techniques like DFT, etc.) … OK. So, without any further ado, let me jot down the actual list.  I will subdivide it in several sub-sections

II.0. Junior-college (American high-school) level:

Obvious:

• Resnick and Halliday.
• Thomas and Finney. Also, Allan Jeffrey

II.1. Initial, college physics level:

• “Modern physics” by Beiser, or equivalent
• Optional but truly helpful: “Physical chemistry” by Atkins, or equivalent, i.e., only the parts relevant to QM. (I know engineers often tend to ignore the chemistry books, but they should not. In my experience, often times, chemistry books do a superior job of explaining physics. Physics, to paraphrase a witticism, is far too important to be left to the physicists!)

II.2. Preparatory material for some select topics:

• “Physics of waves” by Howard Georgi. Excellence written all over, but precisely for the same reason, take care to avoid the temptation to get stuck in it!
• Maths: No particular book, but a representative one would be Kreyszig, i.e., with Thomas and Finney or Allan Jeffrey still within easy reach.
• There are a few things you have to relearn, if necessary. These include: the idea of the limits of sequences and series. (Yes, go through this simple a topic too, once again. I mean it!). Then, the limits of functions.
Also try to relearn curve-tracing.
• Unlearn (or throw away) all the accounts of complex numbers which remain stuck at the level of how $\sqrt{-1}$ was stupefying, and how, when you have complex numbers, any arbitrary equation magically comes to have roots, etc. Unlearn all that talk. Instead, focus on the similarities of complex numbers to both the real numbers and vectors, and also their differences from each. Unlike what mathematicians love to tell you, complex numbers are not just another kind of numbers. They don’t represent just the next step in the logic of how the idea of numbers gets generalized as go from integers to real numbers. The reason is this: Unlike the integers, rationals, irrationals and reals, complex numbers take birth as composite numbers (as a pair of numbers that is ordered too), and they remain that way until the end of their life. Get that part right, and ignore all the mathematicians’ loose talk about it.
Study complex numbers in a way that, eventually, you should find yourself being comfortable with the two equivalent ways of modeling physical phenomena: as a set of two coupled real-valued differential equations, and as a single but complex-valued differential equation.
• Also try to become proficient with the two main expansions: the Taylor, and the Fourier.
• Also develop a habit of quickly substituting truncated expansions (i.e., either a polynomial, or a sum complex exponentials having just a few initial harmonics, not an entire infinity of them) into any “arbitrary” function as an ansatz, and see how the proposed theory pans out with these. The goal is to become comfortable, at the same time, with a habit of tracing conceptual pathways to the meaning of maths as well as with the computational techniques of FDM, FEM, and FFT.
• The finite differences approximation: Also, learn the art of quickly substituting the finite differences ($\Delta$‘s) in place of the differential quantities ($d$ or $\partial$) in a differential equation, and seeing how it pans out. The idea here is not just the computational modeling. The point is: Every differential equation has been derived in reference to an elemental volume which was then taken to a vanishingly small size. The variation of quantities of interest across such (infinitesimally small) volume are always represented using the Taylor series expansion.
(That’s correct! It is true that the derivations using the variational approach don’t refer to the Taylor expansion. But they also don’t use infinitesimal volumes; they refer to finite or infinite domains. It is the variation in functions which is taken to the vanishingly small limit in their case. In any case, if your derivation has an infinitesimall small element, bingo, you are going to use the Taylor series.)
Now, coming back to why you must learn develop the habit of having a finite differences approximation in place of a differential equation. The thing is this: By doing so, you are unpacking the derivation; you are traversing the analysis in the reverse direction, you are by the logic of the procedure forced to look for the physical (or at least lower-level, less abstract) referents of a mathematical relation/idea/concept.
While thus going back and forth between the finite differences and the differentials, also learn the art of tracing how the limiting process proceeds in each such a case. This part is not at all as obvious as you might think. It took me years and years to figure out that there can be infinitesimals within infinitesimals. (In fact, I have blogged about it several years ago here. More recently, I wrote a PDF document about how many numbers are there in the real number system, which discusses the same idea, from a different angle. In any case, if you were not shocked by the fact that there can be an infinity of infinitesimals within any infinitesimal, either think sufficiently long about it—or quit studying foundations of QM.)

II.3. Quantum chemistry level (mostly concerned with only the TISE, not TDSE):

• Optional: “QM: a conceptual approach” by Hameka. A fairly well-written book. You can pick it up for some serious reading, but also try to finish it as fast as you can, because you are going to relean the same stuff once again through the next book in the sequence. But yes, you can pick it up; it’s only about 200 pages.
• “Quantum chemistry” by McQuarrie. Never commit the sin of bypassing this excellent book.
A suggestion: Once you finish reading through this particular book, take a small (40 page) notebook, and write down (in the long hand) just the titles of the sections of each chapter of this book, followed by a listing of the important concepts / equations / proofs introduced in it. … You see, the section titles of this book themselves are complete sentences that encapsulate very neat nuggets. Here are a couple of examples: “5.6: The harmonic oscillator accounts for the infrared spectrum of a diatomic molecule.” Yes, that’s a section title! Here is another: “6.2: If a Hamiltonian is separable, then its eigenfunctions are products of simpler eigenfunctions.” See why I recommend this book? And this (40 page notebook) way of studying it?
• “Quantum physics of atoms, molecules, solids, nuclei, and particles” (yes, that’s the title of this single volume!) by Eisberg and Resnick. This Resnick is the same one as that of Resnick and Halliday. Going through the same topics via yet another thick book (almost 850 pages) can get exasperating, at least at times. But guess if you show some patience here, it should simplify things later. …. Confession: I was too busy with teaching and learning engineering topics like FEM, CFD, and also with many other things in between. So, I could not find the time to read this book the way I would have liked to. But from whatever I did read (and I did go over a fairly good portion of it), I can tell you that not finishing this book was a mistake on my part. Don’t repeat my mistake. Further, I do keep going back to it, and may be as a result, I would one day have finished it! One more point. This book is more than quantum chemistry; it does discuss the time-dependent parts too. The only reason I include it in this sub-section (chemistry) rather than the next (physics) is because the emphasis here is much more on TISE than TDSE.

II.4. Quantum physics level (includes TDSE):

• “Quantum physics” by Alastair I. M. Rae. Hands down, the best book in its class. To my mind, it easily beats all of the following: Griffiths, Gasiorowicz, Feynman, Susskind, … .
Oh, BTW, this is the only book I have ever come across which does not put scare-quotes around the word “derivation,” while describing the original development of the Schrodinger equation. In fact, this text goes one step ahead and explicitly notes the right idea, viz., that Schrodinger’s development is a derivation, but it is an inductive derivation, not deductive. (… Oh God, these modern American professors of physics!)
But even leaving this one (arguably “small”) detail aside, the book has excellence written all over it. Far better than the competition.
Another attraction: The author touches upon all the standard topics within just about 225 pages. (He also has further 3 chapters, one each on relativity and QM, quantum information, and conceptual problems with QM. However, I have mostly ignored these.) When a book is of manageable size, it by itself is an overload reducer. (This post is not a portion from a text-book!)
The only “drawback” of this book is that, like many British authors, Rae has a tendency to seamlessly bunch together a lot of different points into a single, bigger, paragraph. He does not isolate the points sufficiently well. So, you have to write a lot of margin notes identifying those distinct, sub-paragraph level, points. (But one advantage here is that this procedure is very effective in keeping you glued to the book!)
• “Quantum physics” by Griffiths. Oh yes, Griffiths is on my list too. It’s just that I find it far better to go through Rae first, and only then come to going through Griffiths.
• … Also, avoid the temptation to read both these books side-by-side. You will soon find that you can’t do that. And so, driven by what other people say, you will soon end up ditching Rae—which would be a grave mistake. Since you can keep going through only one of them, you have to jettison the other. Here, I would advise you to first complete Rae. It’s indispensable. Griffiths is good too. But it is not indispensable. And as always, if you find the time and the inclination, you can always come back to Griffiths.

Starting sometime after finishing the initial UG quantum chemistry level books, but preferably after the quantum physics books, use the following two:

• “Foundations of quantum mechanics” by Travis Norsen. Very, very good. See my “review” here [^]
• “Foundations of quantum mechanics: from photons to quantum computers” by Reinhold Blumel.
Just because people don’t rave a lot about this book doesn’t mean that it is average. This book is peculiar. It does look very average if you flip through all its pages within, say, 2–3 minutes. But it turns out to be an extraordinarily well written book once you begin to actually read through its contents. The coverage here is concise, accurate, fairly comprehensive, and, as a distinctive feature, it also is fairly up-to-date.
Unlike the other text-books, Blumel gives you a good background in the specifics of the modern topics as well. So, once you complete this book, you should find it easy (to very easy) to understand today’s pop-sci articles, say those on quantum computers. To my knowledge, this is the only text-book which does this job (of introducing you to the topics that are relevant to today’s research), and it does this job exceedingly well.
• Use Blumel to understand the specifics, and use Norsen to understand their conceptual and the philosophical underpinnings.

II.Appendix: Miscellaneous—no levels specified; figure out as you go along:

• “Schrodinger’s cat” by John Gribbin. Unquestionably, the best pop-sci book on QM. Lights your fire.
• “Quantum” by Manjit Kumar. Helps keep the fire going.
• Kreyszig or equivalent. You need to master the basic ideas of the Fourier theory, and of solutions of PDEs via the separation ansatz.
• However, for many other topics like spherical harmonics or calculus of variations, you have to go hunting for explanations in some additional books. I “learnt” the spherical harmonics mostly through some online notes (esp. those by Michael Fowler of Univ. of Virginia) and QM textbooks, but I guess that a neat exposition of the topic, couched in contexts other than QM, would have been helpful. May be there is some ancient acoustics book that is really helpful. Anyway, I didn’t pursue this topic to any great depth (in fact I more or less skipped over it) because as it so happens, analytical methods fall short for anything more complex than the hydrogenic atoms.
• As to the variational calculus, avoid all the physics and maths books like a plague! Instead, learn the topic through the FEM books. Introductory FEM books have become vastly (i.e. categorically) better over the course of my generation. Today’s FEM text-books do provide a clear evidence that the authors themselves know what they are talking about! Among these books, just for learning the variational calculus aspects, I would advise going through Seshu or Fish and Belytschko first, and then through the relevant chapter from Reddy‘s book on FEM. In any case, avoid Bathe, Zienkiewicz, etc.; they are too heavily engineering-oriented, and often, in general, un-necessarily heavy-duty (though not as heavy-duty as Lancosz). Not very suitable for learning the basics of CoV as is required in the UG QM. A good supplementary book covering CoV is noted next.
• “From calculus to chaos: an introduction to dynamics” by David Acheson. A gem of a book. Small (just about 260 pages, including program listings—and just about 190 pages if you ignore them.) Excellent, even if, somehow, it does not appear on people’s lists. But if you ask me, this book is a must read for any one who has anything to do with physics or engineering. Useful chapters exist also on variational calculus and chaos. Comes with easy to understand QBasic programs (and their updated versions, ready to run on today’s computers, are available via the author’s Web site). Wish it also had chapters, say one each, on the mechanics of materials, and on fracture mechanics.
• Linear algebra. Here, keep your focus on understanding just the two concepts: (i) vector spaces, and (ii) eigen-vectors and -values. Don’t worry about other topics (like LU decomposition or the power method). If you understand these two topics right, the rest will follow “automatically,” more or less. To learn these two topics, however, don’t refer to text-books (not even those by Gilbert Strang or so). Instead, google on the online tutorials on computer games programming. This way, you will come to develop a far better (even robust) understanding of these concepts. … Yes, that’s right. One or two games programmers, I very definitely remember, actually did a much superior job of explaining these ideas (with all their complexity) than what any textbook by any university professor does. (iii) Oh yes, BTW, there is yet another concept which you should learn: “tensor product”. For this topic, I recommend Prof. Zhigang Suo‘s notes on linear algebra, available off iMechanica. These notes are a work in progress, but they are already excellent even in their present form.
• Probability. Contrary to a wide-spread impression (and to what one group of QM interpreters say), you actually don’t need much of statistics or probability in order to get the essence of QM right. Whatever you need has already been taught to you in your UG engineering/physics courses.Personally, though I haven’t yet gone through them, the two books on my radar (more from the data science angle) are: “Elementary probability” by Stirzaker, and “All of statistics” by Wasserman. But, frankly speaking, as far as QM itself is concerned, your intuitive understanding of probability as developed through your routine UG courses should be enough, IMHO.
• As to AJP type of articles, go through Dan Styer‘s paper on the nine formulations (doi:10.1119/1.1445404). But treat his paper on the common misconceptions (10.1119/1.18288) with a bit of caution; some of the ideas he lists as “misconceptions” are not necessarily so.
• arXiv tutorials/articles: Sometime after finishing quantum chemistry and before beginning quantum physics, go through the tutorial on QM by Bram Gaasbeek [^]. Neat, small, and really helpful for self-studies of QM. (It was written when the author was still a student himself.) Also, see the article on the postulates by Dorabantu [^]. Definitely helpful. Finally, let me pick up just one more arXiv article: “Entanglement isn’t just for spin” by Dan Schroeder [^]. Comes with neat visualizations, and helps demystify entanglement.
• Computational physics: Several good resources are available. One easy to recommend text-book is the one by Landau, Perez and Bordeianu. Among the online resources, the best collection I found was the one by Ian Cooper (of Univ. of Sydney) [^]. He has only MatLab scripts, not Python, but they all are very well documented (in an exemplary manner) via accompanying PDF files. It should be easy to port these programs to the Python eco-system.

Yes, we (finally) are near the end of this post, so let me add the mandatory catch-all clauses: This list is by no means comprehensive! This list supersedes any other list I may have put out in the past. This list may undergo changes in future.

Done.

OK. A couple of last minute addenda: For contrast, see the article “What is the best textbook for self-studying quantum mechanics?” which has appeared, of all places, on the Forbes!  [^]. (Looks like the QC-related hype has found its way into the business circles as well!) Also see the list at BookScrolling.com: “The best books to learn about quantum physics” [^].

OK. Now, I am really done.

A song I like:
(Marathi) “kiteedaa navyaane tulaa aaThavaave”
Music: Mandar Apte
Singer: Mandar Apte. Also, a separate female version by Arya Ambekar
Lyrics: Devayani Karve-Kothari

[Arya Ambekar’s version is great too, but somehow, I like Mandar Apte’s version better. Of course, I do often listen to both the versions. Excellent.]

[Almost 5000 More than 5,500 words! Give me a longer break for this time around, a much longer one, in fact… In the meanwhile, take care and bye until then…]

# Would it happen to me, too? …Also, other interesting stories / links

1. Would it happen to me, too?

“My Grandfather Thought He Solved a Cosmic Mystery,”

reports Veronique Greenwood for The Atlantic [^] [h/t the CalTech physicist Sean Carroll’s twitter feed]. The story has the subtitle:

“His career as an eminent physicist was derailed by an obsession. Was he a genius or a crackpot?”

If you visit the URL for this story, the actual HTML page which loads into your browser has another title, similar to the one above:

“Science Is Full of Mavericks Like My Grandfather. But Was His Physics Theory Right?”

Hmmm…. I immediately got interested. After all, I do work also on foundations of quantum mechanics. … “Will it happpen to me, too?” I thought.

At this point, you should really go through Greenwood’s article, and continue reading here only after you have finished reading it.

Any one who has worked on any conceptually new approach would find something in Greenwood’s article that resonates with him.

As to me, well, right at the time that attempts were being made to find examiners for my PhD, my guide (and even I) had heard a lot of people say very similar things as Greenwood now reports: “I don’t understand what you are saying, so please excuse me.” This, when I thought that my argument should be accessible even to an undergraduate in engineering!

And now that I continue working on the foundations of QM, having developed a further, completely new (and more comprehensive) approach, naturally, Greenwood’s article got me thinking: “Would it happen to me, too? Once again? What if it does?”

…Naah, it wouldn’t happen to me—that was my conclusion. Not even if I continue talking about, you know, QM!

But why wouldn’t something similar happen to me? Especially given the fact that a good part of it has already happened to me in the past?

The reason, in essence, is simple.

I am not just a physicist—not primarily, anyway. I am primarily an engineer, a computational modeller. That’s why, things are going to work out in a different way for me.

As to my past experience: Well, I still earned my PhD degree. And with it, the most critical part of the battle is already behind me. There is a lot of resistance to your acceptance before you have a PhD. Things do become a lot easier once you have gone successfully past it. That’s another reason why things are going to work out in a different way now. … Let me explain in detail.

I mean to say, suppose that I have a brand-new approach for resolving all the essential quantum mechanical riddles. [I think I actually do!]

Suppose that I try to arrange for a seminar to be delivered by me to a few physics professors and students, say at an IIT, IISER, or so. [I actually did!]

Suppose that they don’t respond very favorably or very enthusiastically. Suppose they are outright skeptical when I say that in principle, it is possible to think of a classical mechanically functioning analog simulator which essentially exhibits all the essential quantum mechanical features. Suppose that they get stuck right at that point—may be because they honestly and sincerely believe that no classical system can ever simulate the very quantum-ness of QM. And so, short of calling me a crack-pot or so, they just directly (almost sternly) issue the warning that there are a lot of arguments against a classical system reproducing the quantum features. [That’s what has actually happened; that’s what one of the physics professors I contacted wrote back to me.]

Suppose, then, that I send an abstract to an international conference or so. [This too has actually happend, too, recently.]

Suppose that, in the near future, the conference organizers too decline my submission. [In actual reality, I still don’t know anything about the status of my submission. It was in my routine searches that I came across this conference, and noticed that I did have about 4–5 hours’ time to meet the abstracts submissions deadline. I managed to submit my abstract within time. But since then, the conference Web site has not got updated. There is no indication from the organizers as to when the acceptance or rejection of the submitted abstracts would be communicated to the authors. An enquiry email I wrote to the organizers has gone unanswered for more than a week by now. Thus, the matter is still open. But, just for the sake of the argument, suppose that they end up rejecting my abstract. Suppose that’s what actually happens.]

So what?

Since I am not a physicist “proper”, it wouldn’t affect me the way it might have, if I were to be one.

… And, that way, I could even say that I am far too smart to let something like that (I mean some deep disappointment or something like that) happen to me! … No, seriously! Let me show you how.

Suppose that the abstract I sent to an upcoming conference was written in theoretical/conceptual terms. [In actual reality, it was.]

Suppose now that it therefore gets rejected.

So what?

I would simply build a computational model based on my ideas. … Here, remember, I have already begun “talking things” about it [^]. No one has come up with a strong objection so far. (May be because they know the sort of a guy I am.)

So, if my proposed abstract gets rejected, what I would do is to simply go ahead and perform a computer simulation of a classical system of this sort (one which, in turn, simulates the QM phenomena). I might even publish a paper or two about it—putting the whole thing in purely classical terms, so that I manage to get it published. (Before doing that, I might even discuss the technical issues involved on blogs, possibly even at iMechanica!)

After such a paper (ostensibly only on the classical mechanics) gets accepted and published, I will simply write a blog post, either here or at iMechanica, noting how that system actually simulates the so-and-so quantum mechanical feature. … Then, I would perform another simulation—say using DFT. (And it is mainly for DFT that I would need help from iMechanicians or so.) After it too gets accepted and published, I will write yet another blog post, explaining how it does show some quantum mechanical-ness. … Who knows such a sequence could continue…

But such a series (of the simulations) wouldn’t be very long, either! The thing is this.

If your idea does indeed simplify certain matters, then you don’t have to argue a lot about it—people can see its truth real fast. Especially if it has to do with “hard” sciences like engineering—even physics!

If your basic idea itself isn’t so good, then, putting it in the engineering terms makes it more likely that even if you fail to get the weakness of your theory, someone else would. All in all, well and good for you.

As to the other possibility, namely, if your idea is good, but, despite putting it in the simpler terms (say in engineering or simulation terms), people still fail to see it, then, well, so long as your job (or money-making potential) itself is not endangered, then I think that it is a good policy to leave the mankind to its own follies. It is not your job to save the world, said Ayn Rand. Here, I believe her. (In fact, I believed in this insight even before I had ever run into Ayn Rand.)

As to the philosophic issues such as those involved in the foundations of QM—well, these are best tackled philosophically, not physics-wise. I wouldn’t use a physics-based argument to take a philosophic argument forward. Neither would I use a philosophical argument to take a physics-argument forward. The concerns and the methods of each are distinctly different, I have come to learn over a period of years.

Yes, you can use a physics situation as being illustrative of a philosophic point. But an illustration is not an argument; it is merely a device to make understanding easier. Similarly, you could try to invoke a philosophic point (say an epistemological point) to win a physics-based argument. But your effort would be futile. Philosophic ideas are so abstract that they can often be made to fit several different, competing, physics-related arguments. I would try to avoid both these errors.

But yes, as a matter of fact, certain issues that can only be described as philosophic ones, do happen to get involved when it comes to the area of the foundations of QM.

Now, here, given the nature of philosophy, and of its typical practitioners today (including those physicists who do dabble in philosophy), even if I become satisfied that I have resolved all the essential QM riddles, I still wouldn’t expect these philosophers to accept my ideas—not immediately anyway. In fact, as I anticipate things, philosophers, taken as a group, would never come to accept my position, I think. Such an happenstance is not necessarily to be ascribed to the personal failings of the individual philosophers (even if a lot of them actually do happen to be world-class stupid). That’s just how philosophy (as a discipline of studies) itself is like. A philosophy is a comprehensive view of existence—whether realistic or otherwise. That’s why it’s futile to expect that all of the philosophers would come to agree with you!

But yes, I would expect them to get the essence of my argument. And, many of them would, actually, get my argument, its logic—this part, I am quite sure of. But just the fact that they do understand my argument would not necessarily lead them to accept my positions, especially the idea that all the QM riddles are thereby resolved. That’s what I think.

Similarly, there also are a lot of mathematicians who dabble in the area of foundations of QM. What I said for philosophers also applies more or less equally well to them. They too would get my ideas immediately. But they too wouldn’t, therefore, come to accept my positions. Not immediately anyway. And in all probability, never ever in my lifetime or theirs.

So, there. Since I don’t expect an overwhelming acceptance of my ideas in the first place, there isn’t going to be any great disappointment either. The very expectations do differ.

Further, I must say this: I would never ever be able to rely on a purely abstract argument. That would feel like too dicey or flimsy to me. I would have to offer my arguments in terms of physically existing things, even if of a brand new kind. And, machines built out of them. At least, some working simulations. I would have to have these. I would not be able to rest on an abstract argument alone. To be satisfactory to me, I would have to actually build a machine—a soft machine—that works. And, doing just this part itself is going to be far more than enough to keep me happy. They don’t have to accept the conceptual arguments or the theory that goes with the design of such (soft) machines. It is enough that I play with my toys. And that’s another reason why I am not likely to derive a very deep sense of disenchantment or disappointment.

But if you ask me, the way I really, really like think about it is this:

If they decline my submission to the conference, I will write a paper about it, and send it, may be, to Sean Carroll or Sabine Hosenfelder or so. … The way I imagine things, he is then going to immediately translate my paper into German, add his own name to ensure its timely publication, and … . OK, you get the idea.

[In the interests of making this post completely idiot-proof, let me add: Here, in this sub-section, I was just kidding.]

2. The problem with the Many Worlds:

“Why the Many Worlds interpretation has many problems.”

Philip Ball argues in an article for the Quanta Mag [^] to the effect that many worlds means no world at all.

No, this is not exactly what he says. But what he says is clear enough that it is this conclusion which becomes inescapable.

As to what he actually says: Well, here is a passage, for instance:

“My own view is that the problems with the MWI are overwhelming—not because they show it must be wrong, but because they render it incoherent. It simply cannot be articulated meaningfully.”

In other words, Ball’s actual position is on the epistemic side, not on the ontic. However, his arguments are clear enough (and they often enough touch on issues that are fundamental enough) that the ontological implications of what he actually says, also become inescapable. OK, sometimes, the article unnecessarily takes detours into non-essentials, even into something like polemics. Still, overall, the write up is very good. Recommended very strongly.

Homework for you: If the Many Worlds idea is that bad, then explain why it might be that many otherwise reasonable people (for instance, Sean Carroll) do find the Many Worlds approach attractive. [No cheating. Think on your own and write. But if cheating is what you must do, then check out my past comment at some blog—I no longer remember where I wrote it, but probably it was on Roger Schlafly’s blog. My comment had tackled precisely this latter issue, in essential terms. Hints for your search: My comment had spoken about data structures like call-stacks and trees, and their unfolding.]

3. QM as an embarrassment to science:

“Why quantum mechanics is an “embarrassment” to science”

Brad Plumer in his brief note at the Washington Post [^] provides a link to a video by Sean Carroll.

Carroll is an effective communicator.

[Yes, he is the same one who I imagine is going to translate my article into German and… [Once again, to make this post idiot-proof: I was just kidding.]]

4. Growing younger…

I happened to take up a re-reading of David Ruelle’s book: “Chance and Chaos”. The last time I read it was in the early 1990s.

I felt younger! … May be if something strikes me while I am going through it after a gap of decades, I will come back and note it here.

5. Good introductory resources on nonlinear dynamics, catastrophe theory, and chaos theory:

If you are interested in the area of nonlinear dynamics, catastrophe theory and chaos theory, here are a few great resources:

• For a long time, the best introduction to the topic was a brief write-up by Prof. Harrison of UToronto; it still remains one of the best [^].
• Prof. Zeeman’s 1976 article for SciAm on the catastrophe theory is a classic. Prof. Zhigang Suo (of Harvard) has written a blog post of title “Recipe for catastrophe”at iMechanica [^], in which he helpfully provides a copy of Zeeman’s article. I have strongly recommended Zeeman’s write-up before, and I strongly recommend it once again. Go through it even if only to learn how to write for the layman and still not lose precision or quality.
• As to a more recent introductory expositions, do see Prof. Geoff Boeing’s blog post: “Chaos theory and the logistic map” [^]. Boeing is a professor of urban planning, and not of engineering, physics, CS, or maths. But it is he who gives the clearest idea about the distinction between randomness and chaos that I have ever run into. (However, I only later gathered that he does have a UG in CS, and a PG in Information Management.) Easy to understand. Well ordered. Overall, very highly recommended.

Apart from it all:

Happy Diwali!

A song I like:

(Hindi) “tere humsafar geet hai tere…”
Music: R. D. Burman
Singers: Kishore Kumar, Mukesh, Asha Bhosale
Lyrics: Majrooh Sultanpuri

[Has this song been lifted from some Western song? At least inspired from one?

Here are the reasons for this suspicion: (1) It has a Western-sounding tune. It doesn’t sound Indian. There is no obvious basis either in the “raag-daari,” or in the Indian folk music. (ii) There are (beautiful) changes in the chords here. But there is no concept of chords in the traditional Indian music—basically, there is no concept of harmony in it, only of melody. (iii) Presence of “yoddling” (if that’s the right word for it). That too, by a female singer. That too, in the early 1970’s! Despite all  the “taan”s and “firat”s and all that, this sort of a thing (let’s call it yoddling) has never been a part of the traditional Indian music.

Chances are good that some of the notes were (perhaps very subconsciously) inspired from a Western tune. For instance, I can faintly hear “jingle bells” in the refrain. … But the question is: is there a more direct correspondence to a Western tune, or not.

And, if it was not lifted or inspired from a Western song, then it’s nothing but a work of an absolute genius. RD anyway was one—whether this particular song was inspired from some other song, or not.

But yes, I liked this song a great deal as a school-boy. It happened to strike me once again only recently (within the last couple of weeks or so). I found that I still love it just as much, if not more.]

[As usual, may be I will come back tomorrow or so, and edit/streamline this post a bit. One update done on 2018.11.04 08:26 IST. A second update done on 2018.11.04 21:01 IST. I will now leave this post in whatever shape it is in. Got to move on to trying out a few things in Python and all. Will keep you informed, probably after Diwali. In the meanwhile, take care and bye for now…]

# The bouncing droplets imply having to drop the Bohmian approach?

If you are interested in the area of QM foundations, then may be you should drop everything at once, and go, check out the latest pop-sci news report: “Famous experiment dooms alternative to quantum weirdness” by Natalie Wolchover in the Quanta Magazine [^].

Remember the bouncing droplets experiments performed by Yves Couder and pals? In 2006, they had reported that they could get the famous interference pattern even if the bouncing droplets passed through the double slit arrangement only one at a time. … As the Quanta article now reports, it turns out that when other groups in the USA and France tried to reproduce this result (the single-particle double-slit interference), they could not.

“Repeat runs of the experiment, called the “double-slit experiment,” have contradicted Couder’s initial results and revealed the double-slit experiment to be the breaking point of both the bouncing-droplet analogy and de Broglie’s pilot-wave vision of quantum mechanics.”

Well, just an experimental failure or two in reproducing the interference, by itself, wouldn’t make for a “breaking point,”i.e., if the basic idea itself were to be sound. So the question now becomes whether the basic idea itself is sound enough or not.

Turns out that a new argument has been put forth, in the form of a thought experiment, which reportedly shows why and how the very basic idea itself must be regarded as faulty. This thought experiment has been proposed by a Danish professor of fluid dynamics, Prof. Tomas Bohr. (Yes, there is a relation: Prof. Tomas Bohr is a son of the Nobel laureate Aage Bohr, i.e., a grandson of the Nobel laureate Niels Bohr [^].)

Though related to QM foundations, this thought experiment is not very “philosophical” in nature; on the contrary, it is very, very “physics-like.” And the idea behind it also is “simple.” … It’s one of those ideas which make you exclaim “why didn’t I think of it before?”—at least the first time you run into it. Here is an excerpt (which actually is the caption for an immediately understandable diagram):

“Tomas Bohr’s variation on the famous double-slit experiment considers what would happen if a particle must go to one side or the other of a central dividing wall before passing through one of the slits. Quantum mechanics predicts that the wall will have no effect on the resulting double-slit interference pattern. Pilot-wave theory, however, predicts that the wall will prevent interference from happening.”

… Ummm… Not quite.

From whatever little I know about the pilot-wave theory, I think that the wall wouldn’t prevent the interference from occurring, even if you use this theory. … It all seems to depend on how you interpret (and/or extend) the pilot-wave theory. But if applied right (which means: in its own spirit), then I guess that the theory is just going to reproduce whatever it is that the mainstream QM predicts. Given this conclusion I have drawn about this approach, I did think that the above-quoted portion was a bit misleading.

The main text of the article then proceeds to more accurately point out the actual problem (i.e., the way Prof. Tomas Bohr apparently sees it):

“… the dividing-wall thought experiment highlights, in starkly simple form, the inherent problem with de Broglie’s idea. In a quantum reality driven by local interactions between a particle and a pilot wave, you lose the necessary symmetry to produce double-slit interference and other nonlocal quantum phenomena. An ethereal, nonlocal wave function is needed that can travel unimpeded on both sides of any wall. [snip] But with pilot waves, “since one of these sides in the experiment carries a particle and one doesn’t, you’ll never get that right. You’re breaking this very important symmetry in quantum mechanics.””

But isn’t the pilot wave precisely ethereal and nonlocal in nature, undergoing instantaneous changes to itself at all points of space? Doesn’t the pilot theory posit that this wave doesn’t consist of anything material that does the waving but is just a wave, all by itself?

…So, if you think it through, people seem to be mixing up two separate issues here:

1. One issue is whether it will at all be possible for any real physical experiment done up with the bouncing droplets to be able to reproduce the predictions of QM or not.
2. An entirely different issue is whether, in Bohr’s dividing-wall thought-experiment, the de Broglie-Bohm approach actually predicts something that is at a variance from what QM predicts or not.

These two indeed are separate issues, and I think that the critics are right on the first count, but not necessarily on the second.

Just to clarify: The interference pattern as predicted by the mainstream QM itself would undergo a change, a minor but a very definite change, once you introduce the middle dividing wall; it would be different from the pattern obtained for the “plain-vanilla” version of the interference chamber. And if what I understand about the Bohmian mechanics is correct, then it too would proceed to  produce exactly the same patterns in both these cases.

With that said, I would still like to remind you that my own understanding of the pilot-wave theory is only minimal, mostly at the level of browsing of the Wiki and a few home pages, and going through a few pop-sci level explanations by a few Bohmians. I have never actually sat down to actually go through even one paper on it fully (let alone systematically study an entire book or a whole series of articles on this topic).

For this reason, I would rather leave it to the “real” Bohmians to respond to this fresh argument by Prof. Tomas Bohr.

But yes, a new argument—or at least, an old argument but in a remarkably new settings—it sure seems to be.

How would the Bohmians respond?

If you ask me, from whatever I have gathered about the Bohmians and their approach, I think that they are simply going to be nonchalant about this new objection, too. I don’t think that you could possibly hope to pin them down with this argument either. They are simply going to bounce back, just like those drops. And the reason for that, in turn, is what I mentioned already here in this post: their pilot-wave is both ethereal and nonlocal in the first place.

So, yes, even if Wolchover’s report does seem to be misguided a bit, I still liked it, mainly because it was informative on both the sides: experimental as well as theoretical (viz., as related to the new thought-experiment).

In conclusion, even if the famous experiment does not doom this (Bohmian) alternative to the quantum weirdness, the basic reason for its unsinkability is this:

The Bohmian mechanics is just as weird as the mainstream QM is—even if the Bohmians habitually and routinely tell you otherwise.

When a Bohmian tells you that his theory is “sensible”/“realistic”/etc/, what he is talking about is: the nature of his original ambition—but not the actual nature of his actual theory.

To write anything further about QM is to begin dropping hints to my new approach. So let me stop right here.

[But yes, I am fully ready willing from my side to disclose all details about it at any time to a suitable audience. … Let physics professors in India respond to my requests to let me conduct an informal (but officially acknowledged) seminar on my new approach, and see if I get ready to deliver it right within a week’s time, or not!

[Keep waiting!]]

Regarding other things, as you know, the machine I am using right now is (very) slow. Even then, I have managed to run a couple of 10-line Python scripts, using VSCode.

I have immediately taken to liking this IDE “code-editor.” (Never had tried it before.) I like it a lot. … Just how much?

I think I can safely say that VSCode is the best thing to have happened to the programming world since VC++ 6 about two decades ago.

Yes, I have already stopped using PyCharm (which, IMHO, is now the second-best alternative, not the best).

No songs section this time, because I have already run a neat and beautiful song just yesterday. (Check out my previous post.) … OK, if some song strikes me in a day or two, I will return here to add it. Else, wait until the next time around. … Until then, take care and bye for now…

[Originally published on 16 October 2018 22:09 hrs IST. Minor editing (including to the title line) done by 17 October 2018 08:09 hrs IST.]