“Measure for Measure”—a pop-sci video on QM

This post is about a video on QM for the layman. The title of the video is: “Measure for Measure: Quantum Physics and Reality” [^]. It is also available on YouTube, here [^].

I don’t recall precisely where on the ‘net I saw the video being mentioned. Anyway, even though its running time is 01:38:43 (i.e. 1 hour, 38 minutes, making it something like a full-length feature film), I still went ahead, downloaded it and watched it in full. (Yes, I am that interested in QM!)

The video was shot live at an event called “World Science Festival.” I didn’t know about it beforehand, but here is the Wiki on the festival [^], and here is the organizer’s site [^].

The event in the video is something like a panel discussion done on stage, in front of a live audience, by four professors of physics/philosophy. … Actually five, including the moderator.

Brian Greene of Columbia [^] is the moderator. (Apparently, he co-founded the World Science Festival.) The discussion panel itself consists of: (i) David Albert of Columbia [^]. He speaks like a philosopher but seems inclined towards a specific speculative theory of QM, viz. the GRW theory. (He has that peculiar, nasal, New York accent… Reminds you of Dr. Harry Binswanger—I mean, by the accent.) (ii) Sheldon Goldstein of Rutgers [^]. He is a Bohmian, out and out. (iii) Sean Carroll of CalTech [^]. At least in the branch of the infinity of the universes in which this video unfolds, he acts 100% deterministically as an Everettian. (iv) Ruediger Schack of Royal Holloway (the spelling is correct) [^]. I perceive him as a QBist; guess you would, too.

Though the video is something like a panel discussion, it does not begin right away with dudes sitting on chairs and talking to each other. Even before the panel itself assembles on the stage, there is a racy introduction to the quantum riddles, mainly on the wave-particle duality, presented by the moderator himself. (Prof. Greene would easily make for a competent TV evangelist.) This part runs for some 20 minutes or so. Then, even once the panel discussion is in progress, it is sometimes interwoven with a few short visualizations/animations that try to convey the essential ideas of each of the above viewpoints.

I of course don’t agree with any one of these approaches—but then, that is an entirely different story.

Coming back to the video, yes, I do want to recommend it to you. The individual presentations as well as the panel discussions (and comments) are done pretty well, in an engaging and informal way. I did enjoy watching it.

The parts which I perhaps appreciated the most were (i) the comment (near the end) by David Albert, between 01:24:19–01:28:02, esp. near 1:27:20 (“small potatoes”) and, (ii) soon later, another question by Brian Greene and another answer by David Albert, between 01:33:26–01:34:30.

In this second comment, David Albert notes that “the serious discussions of [the foundational issues of QM] … only got started 20 years ago,” even though the questions themselves do go back to about 100 years ago.

That is so true.

The video was recorded recently. About 20 years ago means: from about mid-1990s onwards. Thus, it is only from mid-1990s, Albert observes, that the research atmosphere concerning the foundational issues of QM has changed—he means for the better. I think that is true. Very true.

For instance, when I was in UAB (1990–93), the resistance to attempting even just a small variation to the entrenched mainstream view (which means, the Copenhagen interpretation (CI for short)) was so enormous and all pervading, I mean even in the US/Europe, that I was dead sure that a graduate student like me would never be able to get his nascent ideas on QM published, ever. It therefore came as a big (and a very joyous) surprise to me when my papers on QM actually got accepted (in 2005). … Yes, the attitudes of physicists have changed. Anyway, my point here is, the mainstream view used to be so entrenched back then—just about 20 years ago. The Copenhagen interpretation still was the ruling dogma, those days. Therefore, that remark by Prof. Albert does carry some definite truth.

Prof. Albert’s observation also prompts me to pose a question to you.

What could be the broad social, cultural, technological, economic, or philosophic reasons behind the fact that people (researchers, graduate students) these days don’t feel the same kind of pressure in pursuing new ideas in the field of Foundations of QM? Is the relatively greater ease of publishing papers in foundations of QM, in your opinion, an indication of some negative trends in the culture? Does it show a lowering of the editorial standards? Or is there something positive about this change? Why has it become easier to discuss foundations of QM? What do you think?

I do have my own guess about it, and I would sure like to share it with you. But before I do that, I would very much like to hear from you.

Any guesses? What could be the reason(s) why the serious discussions on foundations of QM might have begun to occur much more freely only after mid-1990s—even though the questions had been raised as early as in 1920s (or earlier)?

Over to you.

Greetings in advance for the Republic Day. I [^] am still jobless.




The Infosys Prizes, 2015

I realized that it was the end of November the other day, and it somehow struck me that I should check out if there has been any news on the Infosys prizes for this year. I vaguely recalled that they make the yearly announcements sometime in the last quarter of a year.

Turns out that, although academic bloggers whose blogs I usually check out had not highlighted this news, the prizes had already been announced right in mid-November [^].

It also turns out also that, yes, I “know”—i.e., have in-person chatted (exactly once) with—one of the recipients. I mean Professor Dr. Umesh Waghmare, who received this year’s award for Engineering Sciences [^]. I had run into him in an informal conference once, and have written about it in a recent post, here [^].

Dr. Waghmare is a very good choice, if you ask me. His work is very neat—I mean both the ideas which he picks out to work on, and the execution on them.

I still remember his presentation at that informal conference (where I chatted with him). He had talked about a (seemingly) very simple idea, related to graphene [^]—its buckling.

Here is my highly dumbed down version of that work by Waghmare and co-authors. (It’s dumbed down a lot—Waghmare et al’s work was on buckling, not bending. But it’s OK; this is just a blog, and guess I have a pretty general sort of a “general readership” here.)

Bending, in general, sets up a combination of tensile and compressive stresses, which results in the setting up of a bending moment within a beam or a plate. All engineers (except possibly for the “soft” branches like CS and IT) study bending quite early in their undergraduate program, typically in the second year. So, I need not explain its analysis in detail. In fact, in this post, I will write only a common-sense level description of the issue. For technical details, look up the Wiki articles on bending [^] and buckling [^] or Prof. Bower’s book [^].

Assuming you are not an engineer, you can always take a longish rubber eraser, hold it so that its longest edge is horizontal, and then bend it with a twist of your fingers. If the bent shape is like an inverted ‘U’, then, the inner (bottom) surface has got compressed, and the outer (top) surface has got stretched. Since compression and tension are opposite in nature, and since the eraser is a continuous body of a finite height, it is easy to see that there has to be a continuous surface within the volume of the eraser, some half-way through its height, where there can be no stresses. That’s because, the stresses change sign in going from the compressive stress at the bottom surface to the tensile stresses on the top surface. For simplicity of mathematics, this problem is modeled as a 1D (line) element, and therefore, in elasticity theory, this actual 2D surface is referred to as the neutral axis (i.e. a line).

The deformation of the eraser is elastic, which means that it remains in the bent state only so long as you are applying a bending “force” to it (actually, it’s a moment of a force).

The classical theory of bending allows you to relate the curvature of the beam, and the bending moment applied to it. Thus, knowing bending moment (or the applied forces), you can tell how much the eraser should bend. Or, knowing how much the eraser has curved, you can tell how big a pair of fforces would have to be applied to its ends. The theory works pretty well; it forms of the basis of how most buildings are designed anyway.

So far, so good. What happens if you bend, not an eraser, but a graphene sheet?

The peculiarity of graphene is that it is a single atom-thick sheet of carbon atoms. Your usual eraser contains billions and billions of layers of atoms through its thickness. In contrast, the thickness of a graphene sheet is entirely accounted for by the finite size of the single layer of atoms. And, it is found that unlike thin paper, the graphen sheet, even if it is the the most extreme case of a thin sheet, actually does offer a good resistance to bending. How do you explain that?

The naive expectation is that something related to the interatomic bonding within this single layer must, somehow, produce both the compressive and tensile stresses—and the systematic variation from the locally tensile to the locally compressive state as we go through this thickness.

Now, at the scale of single atoms, quantum mechanical effects obviously are dominant. Thus, you have to consider those electronic orbitals setting up the bond. A shift in the density of the single layer of orbitals should correspond to the stresses and strains in the classical mechanics of beams and plates.

What Waghmare related at that conference was a very interesting bit.

He calculated the stresses as predicted by (in my words) the changed local density of the orbitals, and found that the forces predicted this way are way smaller than the experimentally reported values for graphene sheets. In other words, the actual graphene is much stiffer than what the naive quantum mechanics-based model shows—even if the model considers those electronic orbitals. What is the source of this additional stiffness?

He then showed a more detailed calculation (i.e. a simulation), and found that the additional stiffness comes from a quantum-mechanical interaction between the portions of the atomic orbitals that go off transverse to the plane of the graphene sheet.

Thus, suppose a graphene sheet is initially held horizontally, and then bent to form an inverted U-like curvature. According to Waghmare and co-authros, you now have to consider not just the orbital cloud between the atoms (i.e. the cloud lying in the same plane as the graphene sheet) but also the orbital “petals” that shoot vertically off the plane of the graphene. Such petals are attached to nucleus of each C atom; they are a part of the electronic (or orbital) structure of the carbon atoms in the graphene sheet.

In other words, the simplest engineering sketch for the graphene sheet, as drawn in the front view, wouldn’t look like a thin horizontal line; it would also have these small vertical “pins” at the site of each carbon atom, overall giving it an appearance rather like a fish-bone.

What happens when you bend the graphene sheet is that on the compression side, the orbital clouds for these vertical petals run into each other. Now, you know that an orbital cloud can be loosely taken as the electronic charge density, and that the like charges (e.g. the negatively charged electrons) repel each other. This inter-electronic repulsive force tends to oppose the bending action. Thus, it is the petals’ contribution which accounts for the additional stiffness of the graphene sheet.

I don’t know whether this result was already known to the scientific community back then in 2010 or not, but in any case, it was a very early analysis of bending of graphene. Further, as far as I could tell, the quality of Waghmare’s calculations and simulations was very definitely superlative. … You work in a field (say computational modeling) for some time, and you just develop a “nose” of sorts, that allows you to “smell” a superlative calculation from an average one. Particularly so, if your own skills on the calculations side are rather on the average, as happens to be the case with me. (My strengths are in conceptual and computational sides, but not on the mathematical side.) …

So, all in all, it’s a very well deserved prize. Congratulations, Dr. Waghmare!


A Song I Like:

(The so-called “fusion” music) “Jaisalmer”
Artists: Rahul Sharma (Santoor) and Richard Clayderman (Piano)
Album: Confluence

[As usual, may be one more editing pass…]


The Bhatnagar prizes 2015

The Bhatnagar prizes [^] for 2015 have been announced [(.PDF) ^]. The selections seem to be, as usual, the “safe” ones. So there can’t be much to comment on, on that count.

So, let me try to squeeze out something interesting and relevant from that bit of the news.

As far as I am concerned, the first interesting bit is this: I “know”—i.e. have run into and exchanged a few words with—one of the awardees. Exactly once, at a conference. The fellow in question is Dr. Mandar Deshmukh (2015, Physical Sciences). From the presentation he made at that conference, it was quite clear (at least to me) that he was doing some neat science. While making his presentation, he had assumed that informal and abstract air which by now has become typical for the relatively younger IIT Bombay graduates. I do like this change in them. Earlier, i.e. in my times and earlier, they used to be far too arrogant, pompous, or self-assuming. Even in their informal presentations. Important to me, Deshmukh carried the same air of informality (of a kind of friendliness, almost) during the in-person chat that I had with him on the side-lines during the buffet lunch. Why, he even casually asked me (as others) to “drop by [his] lab and have a look at the equipment any time,” adding that it was “interesting,” with a glint in his eye. Hmmm… Turns out that he has continued doing “interesting” things. (This conference was in 2009 or 2010.) As far as I am concerned, this selection seems quite right. So, congratulations, Dr. Deshmukh!

The second interesting bit is that Deshmukh was the second person present at that conference with who I had chatted during lunch and who eventually got the Bhatnagar award. The first person was Dr. Umesh Waghmare. (Yet another younger IIT Bombay alumnus.)

To go on to the third interesting bit, let me note that it was not a very “official” kind of a conference. It was just a symposium arranged to honor Professor Dilip Kanhere, on the occasion of his retirement as a Professor of Physics in the (now S. P.) University of Pune. There were no brownie points to be scored from this conference; people got together only out of respect for the retiring professor—and of course, out of the love of the research topics. Important to note: People had dropped by from as far places as the USA, Germany, Sweden, etc. (I came to know Prof. Kanhere through Web searches; he had just founded the Center for Modeling and Simulation; I was interesting in anything combining computation and physics. I approached him; he allowed me to attend his classes and generally roam around in the CMS for a while.)

So, the interesting bit is the knack that Prof. Kanhere evidently has to gather together some talented (and/or interesting) people. [I don’t mean to refer to me here.] I don’t know why not every professor succeeds doing that. But some professors do have this knack. Talented folks somehow “smell” such people and almost as if “by default” gather around them. Consider Kanhere’s PhD students (or research associates), and compare them to any randomly selected PhD from any department at the S. P. University of Pune during the same time; Kanhere’s students (and associates) stand out. The current director of CMS, Anjali Kshirsagar, is his PhD student; many others have had post-docs at good institutes abroad, which, incidentally, is a good benchmark for Indian universities (other than the IIXs). This point is important.

Even while working within the “parameters” of this third-class university (I mean the S. P. University of Pune), Kanhere managed to inculcate the right kind of intellectual spirit, and culture in his group, why, even some simple manners and rules of etiquette that researchers from the first-world almost always follow, and a normal guy in the S. P. University of Pune is blissfully (or more likely: arrogantly) unaware of. (Ditto for almost any other Indian university.) At least as far as I am concerned, if I know that if someone has been a student or post-doc with Prof. Kanhere, I immediately know that my emails will not only be read but also replied—and more important, its contents would be thought about before the reply is made (and perhaps also afterwards). It’s something like the atmosphere at iMechanica that Prof. Zhigang Suo has managed to create and maintain. How do some professors succeed doing such a thing regardless of the environment surrounding them? [Compare other blogging fora and iMechanica, on this count: the overall and general civility of the interaction present at iMechanica, combined with the informality. The fact that iMechanica is based at Harvard must have helped to a great extent, but this one factor alone doesn’t explain the outcome.]

So, how is a better atmosphere created? I have no idea. But the point especially relevant to us Indians is: it requires almost no money, almost no hard-work. (Well at least, not the futilely draining kind of a hard-work). And yet, only a few professors ever manage to accomplish that. It’s not everyone’s cup of tea. [As a professor myself, I am too new to know if I could manage to do that. But my point is: I would like to at least try.]

There is a value in such things. Kanhere’s students (and the people who had gathered for his retirement symposium) happened to be more or less the only people who (i) did not laugh at me when I said I am trying to derive a new view of QM, (ii) did not advise me to go read text-books within the first 5 minutes of my mentioning my published paper (or in the first email (if at all a reply came forth)), and (iii) did not try to avoid me the next time we ran into each other. Indeed, as far as the in-person interaction goes, the only people who have ever thoughtfully and informally commented on my QM ideas were Kanhere’s students. One of his students (then a professor himself) emphasized the complex number nature of the \Psi wave-function, and also brought home the fact that the name random variable is a misnomer, it actually being a function. Another student of his (again himself a professor) emphasized the conjugate nature of energy and time, not just of the momentum and position; see John Baez’ coverage here [^]. He also pointed out quantum chemistry to me; I didn’t know about it (“just substitute it in place of t; you will get it”). This, while people were busy saying to me that they won’t read a paper if it was about QM and written in MS Word, and that I should send the paper to a journal. (If they themselves couldn’t bother to even read the paper, why would they think that a journal could accept it? Blank-out. As far as they were concerned, the fact was that I myself had approached them, and so in that very act, I myself had put them in a higher, advising, position; they would therefore be generous in dispensing advice; the matter ended there as far as they were concerned.)

Reading the post in the plain, it’s impossible to convey what value mere “emphases” can be, because the issues are so generally well known. The point is: within the context of that particular discussion, within the context of that particular cluster of ideas, it’s just this one word emphasis that really gives you the clue. … It’s been more than five years since these comments, and I still marvel at how they got me out of my conceptual difficult spots with these off-hand but thoughtful remarks. (Their clarifications and even casually expressed emphases continue to help me, including during my recent-most brain-storming that I noted just yesterday in the previous post.) Why would only Kanhere’s students do that, despite the individual differences between them?

Thus, to use a cliche, some people manage to bring people together in such a way that 1 and 1 does not become 2; it becomes 11. How do they manage to do that? I have no idea.

How was it that Bohr managed to attract so many talented people to his institute? It is especially relevant to point out to Indians that this “institute,” when it was founded, had only one professor—Bohr himself—and a couple of other support staff. The visitors (like Heisenberg) would be lodged in a top-floor “room” (one having a low slanted roof), in the same building. Why, even as recently as in the late 1990s, the “University Department” at Utrecht had a faculty strength of less than 10—that’s roughly the time when Professor Gerard ‘t Hooft got his Nobel. The “Department” was that small; yet he would manage to attract talented folks from all over the world, i.e., even before the time that he got his Nobel. Sommerfeld had this same knack; look at the list of the PhDs he graduated and the post-docs he nurtured. For an example of the more recent times and from the US, look at the list of John Wheeler’s PhD students and post-docs: Richard Feynman and Kip Thorne count among his PhD students. Kip Thorne himself has been attracting an incredibly large pool of PhD students, post-docs and research associates.

Why do some people succeed attracting talent? Are there any lessons we can draw and learn? Let us not focus only on the Nobel laureates. Really speaking, winners of the Nobel prizes, or their mentors, do not make for a good, fitting example for us Indians. It cannot. Precisely because the achievement in question is so great, the difference in the perceived levels so large, that we Indians actually end up doing is to silently dismiss such instances away without any actual consideration. We cannot draw any lessons from them, for the simple reason that the very possibility of building the super-high-end intellectual hubs is completely surreal to us. [And, our friends and kins in the USA, esp. those in the San Francisco Bay Area, specialize in continually reminding us of the impossibility.]

So, let’s lower our bar a bit. I don’t mind doing that. But lowering the bar doesn’t mean we stop attempting. We can—and must—ask: is it possible to replicate, say, Professor Kanhere’s success, even if Wheeler’s example would be completely surreal to us? Is it possible to create an environment in which a prior PhD failure, esp. the one in engineering (and that too from a US university) runs into a physics professor, and says something using some stupid halting words which effectively convey: he wants to reformulate the foundations of QM. He says that, and still the physics professor doesn’t laugh it away right then and there? Is it possible to create this kind of an environment? Not just at an IIX, but also within the lowly S. P. University of Pune? Yes, it is possible; it has happened. … Is it possible that future Bhatnagar recipients flock together for what basically is just a “send-off” function of a non-IIX professor? Yes, it is possible; it has happened.

And, if such things are possible, then, the next question is: what precisely does it take to make it happen? to replicate it? I would like to know.

Over to you all.

[And, in the meanwhile, congratulations to the fresh Bhatnagar awardees once again, esp. Dr. Deshmukh.]

A Song I Like:
(Hindi) “yeh dil aur un ki nigahon ke saaye”
Music: Jaidev
Lyrics: Jan Nisar Akhtar
Singer: Lata Mangeshkar




Many Quantum Interpretations

Suppose you are a student of engineering—say, of mechanical engineering or materials engineering (of perhaps even of computer engineering). You are taking a course on statistics or experimental methods, and your professor has suggested that you could easily create an interesting experimental apparatus: you could build a physical, particles-based model that illustrates the kind of process lying at the roots of the normal distribution. In other words, you could construct Galton’s board [^]. The professor happens to mention this point in your class only in the passing.

And so, on the next weekend, you go out shopping to the (Hindi) “junaa/chor bazaar” (English: flea market), get a few round rubber pieces, a discarded carom board, and a few ball-bearing balls. You affix the round rubber pieces onto the carom board following that Pascal’s triangle kind of arrangement. At the bottom, you affix a few wooden batten strips so as to collect the rolling balls into the compartmentalized collection bins. In the experiment, you would let the balls roll from the top of the triangle via an input channel, and after they have finished bumping into those various rubber pieces, and then rebounding and rolling down, you collect these balls into those various collection bins at the bottom. As the number of rows and the number of balls goes on increasing, the relative fractions of the balls cumulatively collected in the bottom bins tends towards the normal distribution [^].

Then, you think of an idea. You realize that what the mathematics requires is not this entire physical apparatus in all its physicality, but only certain quantitative aspects of it: the number of balls passing through the different places. And, focusing on the input and output of the system, you decide that the number of balls passing through the input channel at the top and the output channels at the bottom is all you are interested in.

Therefore, you think of some simple spring-loaded hammer-and-bell arrangement (or, on second thoughts, just some simple chiming cylinders of the Feng Shui sort) such that, whenever a ball rolls down through a given channel (input or output), it triggers a bell into chiming. To distinguish the various channels, you arrange to have each bell produce a different musical note. The advantage of this arrangement is that you don’t have to observe a ball as it goes rolling through your apparatus. You can simply hear it the moment it enters the apparatus, and you can hear its collection into each of the distinctive collection bins. Therefore, the only record that you need to keep is that of the musical notes: the input note, and the various output notes, say, Saa, Re, Ga, Ma… etc. (To the Western readers: Do, Re, Mi… or C, D, E…(with the appropriate sharps or flats as necessary)).

You demonstrate your working model in the class. Every one is impressed. Yes, even the professor. Not just him, but in fact, even the girls! They all have liked this idea of the bells…

Once the demonstration is over, as you head back to the hostels whistling, you find yourself toying with some ideas: would it be possible for you to collect all those appreciative glances coming from all those girls together, and use the collection to buy that super-bike with that oil-cooled twin-cylinder engine. … You continue walking, whistling happily over the bell idea…

Just then, you run into this budding physicist who lives in the adjacent hostel block. … He is a bit senior to you. You have always thought that a “wilting intellectual” would be a much more fitting term, but in this moment at least, that one seems to be an unnecessary kind of a detail if not a digression…

This guy—the budding etc. physicist—always carries an expression that is a linear combination of the following orthonormal components: (i) sleepy, (ii) sullen, (iii) dazed, (iv) abstract, (v) disturbed, and (vi) smug. The scalar multipliers along the individual dimensions do change more or less randomly, but the expression vector is always observed to span this six-dimensional space, you know by now. There is no change in the dimensionality of the space as it approaches you, not even on this bright, breezy and cool afternoon, you notice.

By now, you have had enough time to conclude that girls’ appreciative glances won’t buy you that bike. But even this realization wouldn’t hamper your aforementioned mood of utter joy and swelling confidence. You could solve any problem in the world, you are absolutely certain. Even a physicist’s problem. … Even a quantum physicist’s problem….

And so, you decide not to ignore the physicist the way you normally do. Instead, you approach him and offer if you could be of any help to him. … The expression vector collapses from (i) + (iv) + (vi) to mostly (v).  “I am interested in resolving the riddles of QM, you know,” you tell him. The expression vector undergoes some very rapid changes, and then settles down to (v) + (vi). … “Drop by my lab, tomorrow,” he asks you. And, without a single further word, walks away. The expression vector now, you guess, is: (ii) + (iii) + (iv). But neither (v) nor (vi) makes too big a presence in the linear combination. Not bad, you say to yourself… It is yet another affirmation that this is a great day, you conclude.

* * * * *   * * * * *   * * * * *

Next day, you land up in his laboratory in the physics department. His prof is a big shot. And, young. It was only in the last semester that he had joined here on a contract position, after a very successful post-doc at one of top five US schools. He has also managed to bring in a lot of funding and contacts with him, as he came. His lab has acquired some brand new equipment for some new quantum experiments; the equipment has cost millions. The funds even came from the alumni association, you know. …

Your friend isn’t exactly the local guru in the lab—his aspiration is to be a theoretical physicist. But no one objects to his hanging around in the lab—every one knows that the prof may be a big shot, but because he is so young and has arrived only on a contract position, he can’t possibly arrange for separate, cosy, air-conditioned cabins for his theoretical physics students. And therefore, this friend of yours has no option but to make do with an old wooden desk, one that is covered with that government-green felt cloth (but without the glass on its top). The desk is placed in a side-corner in this otherwise new and swanky lab. Even as the two of you settle down at his desk, no one in the lab seems to notice your presence—your own, or, for that matter, even that of your friend! No greetings, no inquiring glances, not even raised eyebrows—nothing. They seem to carry on business as usual….

Your friend steps out to grab a cup of coffee, and then, as you get a bit restless, you try chatting with a few lab folks. There is a shade of respect for you as they come to know that you are a student of that engineering department. The campus-wide workshop [/lab resource/computer centre] comes under your department. In between their daily routine in the lab, they answer your queries about the lab and your friend. “No, we don’t understand the theory he is working on all that well,” they say, “but no matter, he just can’t be a very successful theorist, to be sure,” they tell you in a matter-of-fact tone. “Not a single experiment has yet gone wrong since he began sitting here,” they explain. … And no, they wouldn’t at all mind showing you how their equipment works.

There is a thick, black, metallic table with a lot of regularly drilled holes, serving as some kind of a platform, quite a few dazzlingly shiny steel bars/columns/tubes, looking glasses, flanges complete with gaskets, nuts and bolts, precision-built black enclosures, electronics, and wires, and also a couple of high-end workstations with 24″ monitors.

“What happens,” the lab fellows explain to you, “is that there is this central box in the middle of it all. There is a single quantum source—well not, single quantum, it actually is a stream, but the rate is so low that there is statistically very low chance that more than one quantum could be in the length of the box at any given instant of time. The stream of the statistically single quanta enters the box from this side. Then, there are these seven detectors on the other side. As the detectors detect the quanta, they generate a very small signal. We use this big imported amp, and a high-end data acquisition system, to capture these quantum events of interest to us, and the cables feed the data into these computers here.” They then show you the GUI of the software program. “Here, you see these seven circles in this GUI? Each circle represents one detector. For convenience, the circles carry different colours, in the VIBGYOR sequence. Whenever a detector event occurs, the circle lights up momentarily. It also adds the event to this large, terrabyte database that we maintain. Yes, we also do daily data backups. The software automatically shows you the fractions detected in the various detectors.”

“And what distribution is it? It looks something like the bell curve,” you wonder aloud.

“Wow! You know that, too, huh? … Well, yes, it is the normal curve,” they affirm in delight.

“And, what is inside that box?” you ask.

“That is an invalid question!” Your friend has returned, with only one cup of coffee—the one he is sipping from. All the friendly lab folks somehow begin to disperse in no time, and you follow your friend back to his desk.

Your friend resumes the discussion. He proceeds to cite the Solvay conference, the Bell inequalities, Schrodinger’s dead+alive cat, the EPR debate, Dirac’s anti-matter bubbles, the Stern-Gerlach experiment, the Bohr-Einstein debates, and so on and so forth. All of which proves, he says, that you cannot raise a question like that.

“We can talk meaningfully only of the observable quantum events.”

“That means, the lighting up of those seven VIBGYOR circles?”

Your friend ignores your interjection, and continues. “We can talk meaningfully only of the observable quantum events. But not of what can be there inside that box. That is just a hidden-variables nonsense. But hidden variables, by definition, cannot at all be observed. Ever. Hence, they can have no place in a theory of physics.”

He continues: “Quantum mechanics is a complete theory, an accurate theory. It has been experimentally tested for accuracy to the levels of one part in 1000(followed by many more zeroes), and it has always been found that the theory always gives results that are in complete agreement with the experiment.”

At this point of time, there is an increase in the dimensionality of the expression space; it has now acquired an additional dimension of “triumphant,” and the all the other scalar multipliers have become zero. You know that it is time to leave.

You decide to check out some books from the library before getting back to your hostel. At night, you begin to read them. You also do a lot of Web browsing, well into very late night. You are nowhere.

One day turns into one week, the one week turns into many weeks, then months, then years, and you still are nowhere. But you keep at it—at least intermittently. And then, finally, some realization descends on you. You switch on your computer, log in to your blogging account, and start writing a blog post.

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The Copenhagen Interpretation:

The quantum shows the particle character as it enters the box. It shows a field character once in the box. The field collapses into a particle at the time of detection at one of those seven detectors. Thus, when the quantum is not observed, it exists as a field; when it is observed, it exists as a particle. This is called the Field-Particle Duality.

We cannot arrange the experimental apparatus of the triangular box in such a way that we could simultaneously observe both the field and the particle characters. This is called the Complementarity Principle.

We cannot ever hope to come to know how the quantum collapse occurs—how a field, an entity that is continuously spread over the entire triangular domain, suddenly localizes to a discretely observed particle, i.e., a spatially discontinuous entity or phenomenon.

There is an inherent uncertainty as to which detector a given quantum will hit. This is called the Uncertainty Principle.

However, the relative fraction of the times that quanta will be detected at a given detector, can be mathematically predicted, even if such a prediction can only be in  the probabilistic terms.

The math [sic] is the same as the Newtonian gravity field + the theory of bifurcation points, apart from, of course, the theory of probability.

Quantum mechanics refutes the classical idea that we can measure anything with as much precision as we like. The Uncertainty and the Complementarity Principles in fact imply much more.

The idea is not just that we don’t know how the field-collapse occurs; it is that we cannot ever come to know anything about it. The nature of the empirical facts thrown up by quantum mechanics is like that. Quantum mechanics places a limitation on human knowledge, by introducing uncertainty at its most fundamental level.

The Feynman Interpretation Reformulation:

All that fields vs particles is humbug. It’s a bunch of baloney. Real quantum does not behave that way at all. Real quantum is a particle. Yes, you got it right. This is what we know about quantum mechanics: The real quantum is a particle. But it’s bizarre! You have to construct those nice jazzy diagrams. In this case, the quantum undergoes these processes: a quantum goes from one place to another under the gravity field, or a quantum is absorbed and re-emitted with some momentum. There are many paths that a quantum can take. But there are no gears, ratchets and wheels. It’s all abstract. The 19th century physicists thought with all those mechanical gears and wheels and nails and collisions. But Maxwell got it right. He realized that there are no gears or nails. Maxwell was a smart guy. Also Pascal. Pascal also was a very, very smart guy. He was a mathematician. Pascal’s mathematical triangle is the abstract scheme which quanta somehow follow. There are many paths between different nodes of the Pascal triangle. Let us label the one node in the first row of the Pascal triangle as A, the two nodes in the second row as B1 and B2, those in the third row as C1, C2, C3, and so on and so forth. There are many paths and you have to sum up the quantum’s motion along each of them. For example, suppose there are only three rows. So, there are only a 3-factorial number of nodes: i.e., six in all. And you can connect these six nodes via all these tiny little arrows. And, so, in case there are only three rows to the triangle, you end up with these paths:
A -> B1 -> C1
A -> B1 -> C2
A -> B2 -> C2
A -> B2 -> C3
Of course, as the number of rows increases, the number of paths increases too. The factorial function is like that. It blows up. We spend seven years teaching our graduate students the necessary math [sic] so that they can calculate how these little quanta behave. But the essentials of that abstract mathematical process are very, very simple. I am sure my friend Smriti [/Kiran/Shazia/Shaina/…] can understand it. I thank her for inviting me here. Now, assuming that the path-lengths between the adjacent nodes in those paths are constant, then, the probability that the quantum will arrive at a detector, say, C2, can be calculated by taking the number of paths that have C2 as the final letter (2 here), and dividing it by the total number of paths (4 here). So, the probability in this case is 50.00…% You can calculate the probability to as much precision as you like: just keep on adding the recurring 0! Yes, you can do that. That is a neat trick which I learnt from my high-school teacher.

But no one understands quantum mechanics. Yes, a quantum is a particle. But it is nothing like a classical particle. It is quantum particle. No one understands what it means. No one can understand what it means. What this quantum particle actually does in that triangular box is, it goes over all those paths, before it is detected at any of the detectors. And so, you have to sum over all the paths. That is the way nature has chosen to do her book-keeping. Even if there is only a single quantum, you still have to take all the paths in your calculations. All the paths obtained by joining all those tiny little arrows. So, a single quantum simultaneously goes over the first path, the second path, the third path, etc. How it manages to be every where at the same time? That is something we don’t understand. No one understands. No one can understand. It’s not a classical particle. A classical particle follows only one path at a time. But a quantum particle goes over all the paths at the same time. This is called superposition. But it’s not an ordinary superposition. It is the quantum superposition. And you can calculate the probabilities with it…

And you can build a quantum machine. There is a lot of room at the bottom—in fact, the room goes on becoming bigger and bigger as you go down and further down the Pascal triangle. But, no one understands how this triangular box “really” works. No one ever can.

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The Many Worlds Interpretation:

The essential confusion is about the measurement problem or the field-function collapse, and the probabilistic nature of the detection events.

Therefore, the only valid answer can be that when you conduct a quantum experiment and detect a quantum at a detector, say at C2, this detection event happens in our world. However, there also are other worlds. The mathematical Hilbert space is big enough to contain many worlds! It contains our physical world, as well as every other possible physical world. Let us be polite to all these worlds. In the above example of a Pascal’s triangle of 3 rows, the Hilbert space contains six worlds. As Feynman ingeniously pointed out, as the number of rows increases, the number of physical worlds contained in the mathematical Hilbert space goes up dramatically.

Suppose a quantum goes from row A to B to C following the path: A -> B1 -> C2. But in the process of the quantum going from A to B1 rather than B2, the entire universe branches into a second world. The quantum has gone from A to B1, but this occurrence has happened only in our world. But there is another world in which it actually has gone from A to B2. Even though we cannot observe it, ever. It exists. Hilbert space can be proved to contain it. And similarly, for every branching occasion and every branched out world.

And, let us all be polite: please don’t tell me that there can be only one world. I acknowledge and in fact in my work I encourage the idea that you might have a philosophically interesting idea there. But there are many worlds. And, this idea sounds very plausible even if it may not be immediately compelling, because there are no hidden variables in this theory, and yet everything is deterministic. So, there have to be many worlds. At least, many physicists take very favourably to this idea.

After all, physics is the most fundamental and most abstract science. Computer scientists may think they are the only ones to do the abstract thinking. But they are wrong. When they model the searching and sorting algorithms, they may construct what they call an abstract tree. They may show all the branches and the leaves of this tree data structure at the same time. But, their theories still are not sufficiently abstract. They still insist on telling you that the actual computer actually traverses the tree via only a single pathway at a time—depth-first, or breadth-first, or whatever-first. So, in that sense, they do make a distinction between what is only potentially traversed and what is actually traversed. And, it is this distinction that compels them to have this entire tree only in one world. If they were to think more abstractly, if they were to use the insights of quantum mechanics, they would realize that all the various branches of the tree are actually traversed quite at the same time, but in different worlds.

We the physicists think about the most fundamental principles. We therefore have to be most abstract. And, mathematical. Mathematics is fundamental to physics. Therefore, the Hilbert space is more fundamental than the physical world; it contains all the possible physical worlds. We thus are in logic forced to insist that all the branches and leaves of the tree are physically traversed at the same time. That’s quantum mechanics for you. But simultaneous traversals require many different worlds.

Ergo, there are many worlds. Just the way computer scientists use an entire tree even if only one pathway would be traversed, similarly, we use the entire multiplicity of the physical worlds hidden in the Hilbert space, even if the events occurring only in our world would be observed. This is another reason why we like the MWI: it helps simplify our calculations—apart from, of course, fully satisfactorily solving the measurement problem and the probabilistic nature of quantum phenomena. So what if it takes many worlds! How does that pose a problem?

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A note on a more serious note: The above-discussed analogy is entirely classical, even though it does help pin-point the quantum idiocy to such an astounding extent. In case you don’t know QM, do not let yourself think that the above analogy is what QM is really like. In particular, the system evolution here occurs via the classical Newtonian gravity and momentum exchange, not according to Schrodinger’s equation, and there are no phases here—there are no interference effects. Similarly, in the Feynman interpretation, for a quantum system, depending on the context, the accounting might have to include the additional two paths: A + B1 + C3 and A -> B2 -> C1 paths. So, the analogy as given above remains entirely classical. Even if it helps bring out the quantum idiocy—I mean, not the idiocy of science popularizers, but that of physicists themselves—to this recognizable an extent.

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A Song I Like:
(Hindi) “mila hai kisi kaa jhoomka…”
Music: Salil Choudhary
Singer: Lata Mangeshkar
Lyrics: Shailendra

[Guess I will not bother with this post much further, though, as usual, a chance exists that I might come back and streamline things a bit. The world is quantum.]