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Is string theory still considered to be at the "cutting edge" of science?

 
 
layman
 
Reply Sun 8 Mar, 2015 05:08 am
This article, questioning whether the pursuit of string theory is worthwhile, is close to 15 years old.

Quote:
Is String Theory Even Wrong? Peter Woit

For nearly 18 years now, most advanced mathematical work in theoretical particle physics has centered on something known as string theory...Fifteen years ago Edward Witten of the Institute for Advanced Study made the widely quoted claim that "string theory is a part of 21st-century physics that fell by chance into the 20th century," so perhaps it is now time to begin judging the success or failure of this new way of thinking about particle physics....

String theory predicts that the world has 10 space-time dimensions, in serious disagreement with all the evidence of one's senses. Matching string theory with reality requires that one postulate six unobserved spatial dimensions of very small size wrapped up in one way or another. All the predictions of the theory depend on how you do this, but there are an infinite number of possible choices, and no one has any idea how to determine which is correct....

The second concern is that even the part of string theory that is understood is internally inconsistent. This aspect of the theory relies on a series expansion, an infinite number of terms that one is supposed to sum together to get a result. Whereas each of the terms in the series is probably finite, their sum is almost certainly infinite...

These two problems have been around since the earliest work on string theory, along with the hope that they would somehow cancel each other out.

The experimental situation is similarly bleak. It is best described by Wolfgang Pauli's famous phrase, "It's not even wrong." String theory not only makes no predictions about physical phenomena at experimentally accessible energies, it makes no precise predictions whatsoever....

With such a dramatic lack of experimental support, string theorists often attempt to make an aesthetic argument, professing that the theory is strikingly "elegant" or "beautiful." Because there is no well-defined theory to judge, it's hard to know what to make of these assertions....

...the past 15 years of research in particle theory make depressingly clear one form such an end could take: a perpetual, well-promoted but never-successful investigation of a theory that has no connection with the physical world. If only physicists have the will to abandon a failed project and start looking for some new ideas, this sad fate can be avoided.


http://www.americanscientist.org/issues/pub/is-string-theory-even-wrong/3

Quote:
Peter Woit (born September 11, 1957) is an American theoretical physicist. He is a Senior Lecturer in the Mathematics department at Columbia University. Woit graduated in 1979 from Harvard University with bachelor's and master's degrees in physics. He obtained his PhD in particle theory from Princeton University in 1985, followed by postdoctoral work in theoretical physics at State University of New York at Stony Brook and mathematics at the Mathematical Sciences Research Institute (MSRI) in Berkeley. He spent four years as an assistant professor at Columbia. He now holds a permanent position in the mathematics department, as Senior Lecturer and as Departmental Computer Administrator.


http://en.wikipedia.org/wiki/Peter_Woit

Does anyone here have a good feel for the current status of string theory? I certainly don't.
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Type: Question • Score: 4 • Views: 4,068 • Replies: 59

 
rosborne979
 
  1  
Reply Sun 8 Mar, 2015 10:03 am
@layman,
Unfortunately, String Theory can't be tested, proven or demonstrated and thereby insulates itself from the rigor of the scientific process which has made science so valuable.

String Theory also hasn't provided much of any productive value, and in my opinion that's also a hallmark of a valid theory.

I think String Theory is valuable as an exercise in mathematical modeling and an exploration of dimensional systems, but I doubt that it (by itself) will ever produce anything of direct value to science.
Freeman Dyson wrote:
String cosmology is a part of theoretical physics that has become detached from experiments. String cosmologists are free to imagine universes and multiverses, guided by intuition and aesthetic judgment alone. Their creations must be logically consistent and mathematically elegant, but they are otherwise unconstrained. That is why Wertheim found the official string cosmology conference disconcertingly similar to the unofficial Natural Philosophy conference. The insiders and the outsiders seem to be following the same rules. Both groups are telling stories of imagined worlds, and neither has an assured way of deciding who is right. If the title Physics on the Fringe fits the natural philosophers, the same title also fits the string cosmologists.

The fringe of physics is not a sharp boundary with truth on one side and fantasy on the other. All of science is uncertain and subject to revision. The glory of science is to imagine more than we can prove. The fringe is the unexplored territory where truth and fantasy are not yet disentangled. Hermann Weyl, who was one of the main architects of the relativity and quantum revolutions, said to me once, “I always try to combine the true with the beautiful, but when I have to choose one or the other, I usually choose the beautiful.” Following Weyl’s good example, our string cosmologists are making the same choice.

Garet Lisi wrote:
And how are things going with string theory? The promises and hopes from the 1980s have not worked out. They thought they’d find the right Calabi-Yau manifold and the fermion multiplets and masses would pop out and they’d have the whole thing wrapped up before lunch. But that didn’t happen. String models grew increasingly complicated. And with every fanciful step they made away from the Standard Model, the more likely they were to be wrong; they were mesmerized by their own mathematical constructions, which kept them busy but were much more complex than the Standard Model they were trying to explain. String theory became a postmodernist monstrosity, lumbering forward on self-provided momentum without ever receiving the pruning from experimental verification that physics demands. The closest thing to a physical prediction that string theory has ever produced is that there should be superparticles, but these have not shown up. String theory models lost connection to the physical world. Other physicists and mathematicians were left wondering if string theorists had joined some sort of cult.
layman
 
  1  
Reply Sun 8 Mar, 2015 10:20 am
@rosborne979,
Thanks for the input, Ros.

Quote:
String theory models lost connection to the physical world. Other physicists and mathematicians were left wondering if string theorists had joined some sort of cult.


That's how I (a complete outsider) have felt for a long time (as I know many critics have).

In trying to answer my own question, I read a few articles written within the last year and still can't figure out if its the predominant framework for today's particle physics. I see claims ranging from

1. "string theory, already on life support, is starting to circle the drain..." to
2. "string theory is still the only game in town."


dalehileman
 
  1  
Reply Sun 8 Mar, 2015 10:34 am
@layman,
Quote:
….it accommodates a consistent combination of quantum field theory and general relativity


http://en.wikipedia.org/wiki/String_theory
https://www.google.com/?gws_rd=ssl#q=current+status+of+string+theory

..I have a hunch Lay it might accommodate my relative relativity
0 Replies
 
dalehileman
 
  1  
Reply Sun 8 Mar, 2015 10:41 am
@rosborne979,
Ros, entirely OT but I had got you mixed up with Ora. Thus the following link was intended for you not Ora, with my apologies

http://able2know.org/topic/269753-1
layman
 
  1  
Reply Sun 8 Mar, 2015 01:19 pm
This guy isn't very nice to string theorists, eh?

Quote:
Sheldon Lee Glashow (born December 5, 1932) is a Nobel Prize winning American theoretical physicist. He is the Metcalf Professor of Mathematics and Physics at Boston University and Higgins Professor of Physics, Emeritus, at Harvard University.


Glashow says:

Quote:
There is today a disconnect in the world of physics. Let me put it bluntly. There are physicists, and there are string theorists. Of course the string theorists are physicists, but the string theorists in general will not attend lectures on experimental physics. They will not be terribly concerned about the results of experiments. They will talk to one another.

“I simply can’t imagine why any sane person would imagine, discuss, or mention, except insultingly, the concept of a theory of everything. It's a stupidity.”

...there ain't no experiment that could be done nor is there any observation that could be made that would say, "You guys are wrong." The theory is safe, permanently safe. I ask you, is that a theory of physics or a philosophy?


http://www.pbs.org/wgbh/nova/elegant/view-glashow.html
0 Replies
 
rosborne979
 
  4  
Reply Sun 8 Mar, 2015 01:45 pm
@dalehileman,
dalehileman wrote:

Ros, entirely OT but I had got you mixed up with Ora. Thus the following link was intended for you not Ora, with my apologies

http://able2know.org/topic/269753-1

I've tried to answer your questions in the past Dale. But not matter how hard I try I cannot make any sense of your conjectures. I also feel that you don't make an honest effort to understand anything that is explained to you. It makes taking the time to answer, quite unappealing.
rosborne979
 
  1  
Reply Sun 8 Mar, 2015 01:58 pm
@layman,
layman wrote:
I see claims ranging from

1. "string theory, already on life support, is starting to circle the drain..." to
2. "string theory is still the only game in town."

For me it always comes down to the value a theory provides.

Take UFO speculation for example, even if I could be convinced by a preponderance of anecdotal accounts that extraterrestrial "UFO's" were visiting Earth, it would be unsatisfying if it didn't teach me something about the UFO itself. How did it get here? What energy source does it use? What means of propulsion? What type of being built it? How do those beings function, how do they think?

Likewise, String Theory provides great speculation, but so far no actual value, no insight, no knowledge.

There are too many possibilities within the realm of metaphysical woowoo, such that anything which trespasses within that territory becomes just a drop in an ocean of possibilities. It's testability and functionality and value which separate these things from the satisfying taste of science.
izzythepush
 
  1  
Reply Mon 9 Mar, 2015 04:27 am
0 Replies
 
dalehileman
 
  -1  
Reply Mon 9 Mar, 2015 10:21 am
@rosborne979,
http://able2know.org/topic/269753-1
0 Replies
 
fresco
 
  1  
Reply Mon 9 Mar, 2015 01:09 pm
@rosborne979,
Quote:
String Theory provides great speculation, but so far no actual value, no insight, no knowledge.

Check out this Brian Cox interview for a possible footnote rejoinder to "no insight".
https://www.youtube.com/watch?v=Fkwt2jlvHqM
rosborne979
 
  1  
Reply Mon 9 Mar, 2015 01:39 pm
@fresco,

All I heard there was a long and oversimplified explanation of string theory. I didn't hear any insight. What part of that were you referring to?
layman
 
  1  
Reply Mon 9 Mar, 2015 01:54 pm
@rosborne979,
Quote:
All I heard there was a long and oversimplified explanation of string theory. I didn't hear any insight.


I don't know **** about it, Ros, but, yeah, I'm with you. Susskind who, as I understand it, was one of the earliest advocates of string theory, actually says, in that video, things like "here's the way it works"--and then talks about "gravitrons."

Again my (perhaps mistaken) impression is that gravitrons have never been detected. Also, that, in the 11 dimensions of string (M) theory, the majority of gravitational force "seeps" off into "other universes."

And he packs all of that wild-ass speculation into the "matter of fact" sounding: "Here's the way it works."
0 Replies
 
fresco
 
  1  
Reply Mon 9 Mar, 2015 02:00 pm
@rosborne979,
I was referring to comments that original data from nuclear physics modeled as strings allegedly gave unexpected insight into quantum gravity.
fresco
 
  1  
Reply Mon 9 Mar, 2015 02:25 pm
@rosborne979,
...near the end of clip dealing with history of string models..."to their horror..."
0 Replies
 
rosborne979
 
  1  
Reply Mon 9 Mar, 2015 02:43 pm
@fresco,
Yes, I guess they did use the word "insight", unfortunately that's about as close as they ever got to actually explaining any.

I often get the feeling that string theory is like trying to understand the Empire State Building by constructing a model out of lego's. Then spending 20 years analyzing your lego model in greater and greater detail, only to find out that well, legos are plastic bricks are brick, and no matter how fine-grained you make your model (multiple hyper dimensions), the plastic never turns into brick.
0 Replies
 
Setanta
 
  1  
Reply Mon 9 Mar, 2015 03:14 pm
One of the biggest problems with the string model is that it, if accurate, describes forces and quantities at the level of Planck units. Whether or not one is referring to an accurate model, that's just far too, too small to be measured. The concepts can be modeled, but they can't be measured and they can't be tested. The most positive thing about string theory is that it has made some predictions--sort of (clickity-click). However, until something "see-able" like a wimp (weakly interactive massive particle), turns up, even such a claim as Mr. Duff of Imperial College makes, is going to be as close as anyone can come to establishing string theory, and that's just not very close. Personally, i don't think it should be called string theory, because it has not yet risen to the dignity of scientific theory.
layman
 
  1  
Reply Mon 9 Mar, 2015 03:49 pm
@Setanta,
It's advocates now seem to be arguing that "falsifiability" and, more generally, "empiricism" are no longer adequate standards for assessing what a "scientific" theory is.

ID, anyone?
0 Replies
 
tomr
 
  1  
Reply Mon 9 Mar, 2015 11:02 pm
@layman,
I just started reading a book on string theory called The Elegant Universe by Brian Greene. I am reading it because it was recommended to me by someone who believes in String Theory. We kind of got in a disagreement about whether it was a good theory or not. I said it was a dead theory, mostly because I had not heard of any significant progress in the area. I am against the idea of any theory that cannot be tested, and apparently, for all practical purposes, that is what string theory is. Plus, it comes to some pretty wild conclusions about the dimensionality of space. His response to the lack of experimental support was that he thought that the recent testing for the Higg's boson was somehow evidence for it. That did not sound right to me, but I did not know enough to say anything either way.

I'll read what I will of the book and maybe I'll change my mind, but I doubt it. And the quote by Edward Witten in the article was also in the book. This is a well-timed topic, for me anyway...
layman
 
  1  
Reply Mon 9 Mar, 2015 11:27 pm
@tomr,
Tom, from what I know, Greene has long been a pretty fervent devotee of string theory. Yet in an article by him published in the Smithsonian Magazine a couple of months ago, even he seems to be expressing reservations:

Quote:
Looking back, I’m gratified at how far we’ve come but disappointed that a connection to experiment continues to elude us. While my own research has migrated from highly mathematical forays into extra-dimensional arcana to more applied studies of string theory’s cosmological insights, I now hold only modest hope that the theory will confront data during my lifetime....

Should decades drift by without experimental support, I imagine that string theory will be absorbed by other areas of science and mathematics, and slowly shed a unique identity.


He is also frank enough to acknowledge some questionable aspects of string theory that have raised legitimate doubts and generated substantial criticism:

Quote:
...researchers had discovered ever larger collections of shapes that passed mathematical muster, driving the number of candidates into the thousands, millions, billions and then...into numbers so large that they’ve never been named. Against this embarrassment of riches, string theory offered no directive regarding which shape to pick....The dream of extracting unique predictions from string theory rapidly faded.

Susskind was arguing that if the mathematics does not identify one particular shape as the right one for the extra dimensions, perhaps there isn’t a single right shape...Our universe would then be just one of a vast collection, each with detailed features determined by the shape of their extra dimensions...

With or without string theory, the multiverse is a highly controversial schema, and deservedly so. It not only recasts the landscape of reality, but shifts the scientific goal posts....Most physicists, string theorists among them, agree that the multiverse is an option of last resort...


http://www.smithsonianmag.com/science-nature/string-theory-about-unravel-180953637/?no-ist=&page=2
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