Would Feynman Embrace Background Independence in Quantum Mechanics Today?

[George Jones]

http://www.cbc.ca/quirks/media/2006-2007/mp3/qq-2006-09-23e.mp3"

 

[turbo]

Thank you!

 

[marcus]

Thank you!

yes thanks, what an excellent interview!
http://www.cbc.ca/quirks/media/2006-2007/mp3/qq-2006-09-23e.mp3

Canadian Broadcasting Co.
23 September edition of Quirks and QuarksBTW Peter Woit called attention to this article at the New Yorker website
http://www.newyorker.com/printables/critics/061002crat_atlarge

The article, by Jim Holt, is called "Unstrung", and reviews Smolin's and Woit's books. It will be published in the 2 October issue
of the magazine.and also to this piece in the Scientific American
http://www.sciam.com/article.cfm?articleID=00000749-259B-1514-A59B83414B7F0133
"Is String Theory Unraveling?"

 

[marcus]

yes thanks, what an excellent interview!
http://www.cbc.ca/quirks/media/2006-2007/mp3/qq-2006-09-23e.mp3

Canadian Broadcasting Co.
23 September edition of Quirks and QuarksBTW Peter Woit called attention to this article at the New Yorker website
http://www.newyorker.com/printables/critics/061002crat_atlarge

The article, by Jim Holt, is called "Unstrung", and reviews Smolin's and Woit's books. It will be published in the 2 October issue
of the magazine.

...

here is a sample exerpt from Jim Holt's New Yorker article:

===quote===
...Smolin furnishes the more definite answer. The current problem with physics, he thinks, is basically a problem of style. The initiators of the dual revolution a century ago—Einstein, Bohr, Schrödinger, Heisenberg—were deep thinkers, or “seers.” They confronted questions about space, time, and matter in a philosophical way. The new theories they created were essentially correct. But, Smolin writes, “the development of these theories required a lot of hard technical work, and so for several generations physics was ‘normal science’ and was dominated by master craftspeople.” Today, the challenge of unifying those theories will require another revolution, one that mere virtuoso calculators are ill-equipped to carry out. “The paradoxical situation of string theory—so much promise, so little fulfillment—is exactly what you get when a lot of highly trained master craftspeople try to do the work of seers,” Smolin writes.
The solution is to cultivate a new generation of seers. And what, really, is standing in the way of that? Einstein, after all, didn’t need to be nurtured by the physics establishment, and Smolin gives many examples of outsider physicists in the style of Einstein, including one who spent ten years in a rural farmhouse successfully reinterpreting general relativity. Neither Smolin nor Woit calls for the forcible suppression of string theory. They simply ask for a little more diversity. “We are talking about perhaps two dozen theorists,” Smolin says. This is an exceedingly modest request, for theoretical physics is the cheapest of endeavors. Its practitioners require no expensive equipment. All they need is legal pads and pencils and blackboards and chalk to ply their trade, plus room and board and health insurance and a place to park their bikes. Intellectually daunting as the crisis in physics may be, its practical solution would seem to demand little more than the annual interest on the rounding error of a Google founder’s fortune.
“How strange it would be if the final theory were to be discovered in our own lifetimes!” Steven Weinberg wrote some years ago, adding that such a discovery would mark the sharpest discontinuity in intellectual history since the beginning of modern science, in the seventeenth century. Of course, it is possible that a final theory will never be found, that neither string theory nor any of the alternatives mentioned by Smolin and Woit will come to anything. Perhaps the most fundamental truth about nature is simply beyond the human intellect, the way that quantum mechanics is beyond the intellect of a dog. Or perhaps, as Karl Popper believed, there will prove to be no end to the succession of deeper and deeper theories. And, even if a final theory is found, it will leave the questions about nature that most concern us—how the brain gives rise to consciousness, how we are constituted by our genes—untouched. Theoretical physics will be finished, but the rest of science will hardly notice.
===end quote===

 

[Chronos]

I sympathize with the 'in our lifetime' optimism. This may be nothing more than personal bias, but, I've seen many ideas that seem tantalizingly close to being the 'break' needed to corner the elusive TOE. Should the 'right' TOE arise, I predict the sound of one hand clapping [against foreheads] will be deafening.

 

[Vast]

I understand Smolin’s criticism to string theory, and agree with what he’s saying. While I was listening, he reminded me of something I recently read in “A World Without Time: The Forgotten Legacy of Gödel and Einstein:”

The secret to James Watson and Francis Crick's discovery of the structure of DNA… was as much their realization-almost unique at the time-that the problem was now solvable, as it was their technical competence in fitting together all the pieces that lay scattered about, unconnected, in various workshops

It’s often been said that Einstein had no chance unifying the forces of nature. But more than sixty years on, do string theorists stand any better a chance? Do the pieces lie scattered about? Is the problem solvable?

 

[straycat]

Neither Smolin nor Woit calls for the forcible suppression of string theory. They simply ask for a little more diversity.

You've got to respect Smolin for walkin the walk, not just talkin the talk. I just realized that he is on the scientific advisory panel of the Foundational Questions Institute http://www.fqxi.org/about.html , whose mission is (from their website) "To catalyze, support, and disseminate research on questions at the foundations of physics and cosmology, particularly new frontiers and innovative ideas integral to a deep understanding of reality but unlikely to be supported by conventional funding sources."

...Smolin furnishes the more definite answer. The current problem with physics, he thinks, is basically a problem of style. The initiators of the dual revolution a century ago—Einstein, Bohr, Schrödinger, Heisenberg—were deep thinkers, or “seers.” They confronted questions about space, time, and matter in a philosophical way. The new theories they created were essentially correct. But, Smolin writes, “the development of these theories required a lot of hard technical work, and so for several generations physics was ‘normal science’ and was dominated by master craftspeople.” Today, the challenge of unifying those theories will require another revolution, one that mere virtuoso calculators are ill-equipped to carry out.

So what are the philosophic questions that we should be asking? That is, what are the present-day analogues of space, time, and matter of a century ago? Well there are all sorts of issues to choose from: what is probability, exactly? is the wavefunction "real"? what is the observer? etc etc.

I suppose that the key would be to find something on the borderzone between theory and philosophy. That is, you need a philosophic question whose answer gives you some sort of clue about how to construct a theory; or conversely, you need a theory that requires us to re-think something philosophically. It's really easy to set up camp in just one of these realms and stay there. I would imagine that a philosophy professor might even shy away from suggesting that a theory (and not just its interpretation) should be changed for philosophic reasons. The audacity!

For the Bohmian mechanics supporters, I suppose the answer would be to seek a formulation that respects realism. I suppose Smolin's answer would be to seek a theory that respects background independence as well as diffeomorphism invariance. Start with those, and you get LQG (iiuc).

Here's my own guess on an important question to ask: what is probability? As it turns out, one of the grant winners of the Foundational Questions Institute is Simon Saunders, a philosophy professor at the University of Oxford, who will be organizing a conference which will focus on the interpretation of probability in the multiple worlds interpretation.
http://www.fqxi.org/aw-saunders.html

Maybe the only way to construct a viable theory is to have the "correct" (whatever that would mean) philosophical outlook on a great myriad of issues, and the reason that a theory of quantum gravity has been so elusive is that it's nearly impossible to find two physicists who agree on the philosophical answer to just one question, let alone a myriad. otoh, maybe it's possible to make incremental steps by focusing on one philosophic issue at a time. In any case, I wonder: is there any sort of litmus test that can be used to find the "correct" answer to any given philosophic question?

I don't know, but I do have an idea on how any philosophic question should be approached. The key, I propose, is to focus less on the answer, and more on the question itself. This is what Einstein did (to the best of my understanding) when he was faced with his own deep questions. eg, when he wondered: "what is space?" he replaced it with: how do I measure distances? iow, he rephrased the question, and he understood that it took great rigor and discipline to make sure he was asking the question correctly.

So perhaps every great scientific revolution can be equated with the realization that we were asking some big question incorrectly.

David

 

[selfAdjoint]

Straycat, that was a good post, but on general principles I think questions that have been around a long time without a definite answer (like the nature of the "wave function") will have a bearing on the coming depth breakthrough, but that answers that have been around for a long time without prevailing, like Bohmian mechanics, won't.

I think a place we need to look is "What do you mean by non-local, and what does the Old One mean by it?

 

[alexsok]

That quote forgot to mention "Where did we come from, where are we going after our death and what is the meaning of life"

 

[straycat]

Straycat, that was a good post,

thanks!

but on general principles I think questions that have been around a long time without a definite answer (like the nature of the "wave function") will have a bearing on the coming depth breakthrough,

yup, I agree

but that answers that have been around for a long time without prevailing, like Bohmian mechanics, won't.

One of my favorite analogies is a comparison of QM to a great beast, with each formulation/interpretation (Bohm, MWI, FPI, etc) compared to looking at the beast from a different angle. Each viewpoint gives you correct information about what the beast looks like, but there is not one that can, by itself, give you the complete picture.

I think a place we need to look is "What do you mean by non-local, and what does the Old One mean by it?

ahhh, another good question!

david

 

[Astronuc]

Physicists Debate the Merits of String Theory
http://www.npr.org/templates/story/story.php?storyId=5670911

Talk of the Nation, August 18, 2006 · Is string theory the answer to the last big questions in physics, or a dead end? While some physicists believe that string theory could lead to a unifying theory, detractors say it's sloppy and founded on unwarranted assumptions.

Lee Smolin, author of The Trouble with Physics; faculty member, Perimeter Institute for Theoretical Physics

Brian Greene, author of The Elegant Universe and The Fabric of the Cosmos; professor of mathematics and physics, Columbia University

 

[jal]

I have just listen to it.

Physicists Debate the Merits of String Theory
http://www.npr.org/templates/story/s...toryId=5670911

I liked it.

John Baez
The moral is: for a question like this, you need to know not just the answer but also the assumptions and reasoning that went into the answer. Otherwise you can't make sense of why different people give different answers.

Do you want to help with my question?
(Planck size sphere.)
jal

 

[Astronuc]

Another commentary -

Is String Theory Unraveling?
http://www.npr.org/templates/story/story.php?storyId=6172247

Weekend Edition Saturday, September 30, 2006 · NPR's Scott Simon talks with "Math Guy" Keith Devlin about two new books that call into question the entire idea of string theory. The theory states that tiny vibrating strings make up everything, but some scientists say there is no way to prove or disprove it.

 

[marcus]

This was interesting to read for a student at the beginning level. The so-called "seers" of physics-it would seem that they were educated in a broad way-and saw physics in relation to a large picture. The great contemplative, philosophical attitude is missing from the "virtuoso calculators"? But even great ones like Feynman also had a similar attitude no? And saw Physics as problem solving?

part of Smolin's point is that there are periods in physics where there is little or nothing for "seers" to do and little or no need for philosophical perspective.

some would call these periods of "normal science"----where the necessary big ideas have already been laid out and the effort is to calculate consequences and check experimentally and modify details so as to get the picture more and more correct.

then a period of normal science can begin to run out of steam and progress can slow because most of the calculation and checking and modifying that needs to be done (with those big fundamental guiding ideas) and then they need to change their style and become (as Smolin would say) more like "seers"----or as others might put it more philosophical
(the "shut up and calculate" approach doesn't work as well anymore)

Feynman was smart enough to know what period in the cycle he was in and what the practical style was for making progress. He was mostly in a normal science period where the sensible thing to do was shut up and calculate---there was a lot to be done.

I personally think Feynman was so smart that if he was in THIS PRESENT situation he would be acting differently. He might e.g. see that a fundamentally new (background independent) concept of space and time is needed and NOT be saying "shut up and calculate" to achieve incremental progress. The same person who said shut up and calculate in 1966 might, in 2006, be asking deep questions about quantum mechanics foundations and inventing new models of spacetime and matter----pretty much the same goals as Smolin.

 

[Careful]

I personally think Feynman was so smart that if he was in THIS PRESENT situation he would be acting differently. He might e.g. see that a fundamentally new (background independent) concept of space and time is needed and NOT be saying "shut up and calculate" to achieve incremental progress. The same person who said shut up and calculate in 1966 might, in 2006, be asking deep questions about quantum mechanics foundations and inventing new models of spacetime and matter----pretty much the same goals as Smolin.

I severely doubt that Feynman would consider background independence, his methodology was to use simple systems in which one could compute things easily. However, Feynman was even in the sixties and especially later in the eighties very much aware that new physics was needed with as legacy some creative work in the foundations of quantum mechanics - he was on average 20 years ahead of his time during his life.

Careful