By reading through some of these threads, it seems many of you here don't think string theory is the best approach. Is this merely a personal preference amoung many of the knowledgeable posters here, or have there been some recent problems with string theory, or have there just not been as many recent developments in string theory? Has string theory become a dead end? And I would like to hear your personal oppinions, but I'm also interested in some unbiased information as well. I assume many of the huge players in string theory are still pursuing it? (Ed Witten, Michael Green.. that's about all I know without looking a few more names up ) ?
Good question. There are 2 excellent experiments in the near future that will "make or break" string theory in the next couple years. One of course, is with the Large Hadron Collider 2 years away and the other is with the Laser Interferometer Space Antenna scheduled to launch in 2013. The first will test for sparticles and extra dimensions while the latter will test for gravitational waves produced right after the Big Bang. Both of these experiments could produce much supporting evidence for string theory.
I can't speak for anyone else, but I think string theory [and I used to be a big fan] has hit a reef. The 'landscape' fiasco was really damaging. And appealing to the anthropic principle did not help the cause. It's not a practical approach and still does not produce useful predictions. I'm not biased against ST, but sooner or later any viable theory must produce results [i.e., testable predictions].
I think the rumors of string theory's death are greatly exaggerated. Admittedly supersymmetry by itself faces make or break experiments at the LHC, but people, anticipating this, are lookiong again at non-supersymmetric bosonic string theory, seeing what they can do with the more modern mathematical techniques that have been introduced since it came out in the 1980s.
I think that the biggest threats to string theory are those that propose solutions to the same questions without requiring a large number of dimensions or supersymmetric particles. When you get to a 4-5D solution with just a handful of additional particles and some assumptions about the nature of empty space, that makes specific verifiable predictions about the world it is hard to justify the elaborate edifice of string theory even if it looks pretty.
I think we are seeing the start of a "String Diaspora" symbolized, for me, by the depression that Florian Gmeiner expressed after attending yesterday's panel discussion of "The Next Superstring Revolution". Diaspora is Greek for scattering or dispersion and refers to the historical emigration from Israel after a failed revolution (an unsuccessful uprising against the Roman Empire). And it has the root "spor" reminding us of the scattering of spores or seeds----the verb "sporein" refers to the sowing of grain. http://www.math.columbia.edu/~woit/blog/archives/000218.html http://www.fields.utoronto.ca/programs/scientific/04-05/string-theory/strings2005/panel.html http://golem.ph.utexas.edu/~distler/blog/archives/000593.html Distler was in Toronto, blogging from String 05, and he declined to say anything about the panel discussion (about the state and future of string research), which may turn out to have been the most significant part of the conference. Then Florian Gmeiner said: "Hi, it’s a pity that you don’t comment on the panel discussion. Being a phd student I feel quite depressed after having listened to it. " http://golem.ph.utexas.edu/~distler/blog/archives/000593.html#c002467 And Distler replied that panel discussions like that were a "silly exercise"--- advising Gmeiner to ignore it and get back to work. Imagine what might result from the dispersion of a many smart young mathematically sophisticated people like Florian Gmeiner into other fields. In that sense his depression may be a hopeful sign---a coming to grips with reality that may precipitate constructive action and have fruitful consequences
Urs interest in Category Theory, another hopeful sign https://www.physicsforums.com/showthread.php?p=677042#post677042 I think another hopeful sign is Urs interest in Category Theory, and in particular the celebration in Sydney of category theorist Ron Street that is currently competing for attention with the Toronto String 05 conference. "Categories in Algebra, Geometry and Mathematical Physics Conference in honour of Ross Street's sixtieth birthday July 11-16 2005, Macquarie University, Sydney" http://streetfest.maths.mq.edu.au/ I think it is probably a bit much to expect, or wishful thinking, that resort to Categories will save the superstring/M program, or validate it, or show the way out of the landscape wilderness. It seems more important that Category research has a wide spectrum of potential application in a lot of different directions---it is more apt to show us new things (I imagine) than to validate things we already know. And it is seductively elegant mathematics that can dazzle and absorb young researchers. It offers string people a way out of string, and something that is wonderful and beautiful and arcane to do---with something of the same elite feel or a similar pretension to universality. Category has, I think, the same potential for being hyped as a comprehensive panacea or as something like the philosopher's stone of the alchemists. Plus it might actually be good for something, you never know. The Street festival conference is about Categories as applied with to algebra, geometry, and mathematical physics. In his post Urs CALLS it "Mathematical String Physics" which makes it sound nice and homey but in fact Category Theory has the ability to transform whatever it is applied to, beyond recognition. And I belive that Urs is imperceptively and gradually emigrating to a foreign country. His mind is in Sydney instead of Toronto. Of course I dont know and am just guessing, but these are the signs of a diaspora to me----the depression of the phd student Florian, the excitement of Urs over category. BTW Baez is giving an interesting talk in Sydney. I started a thread
String theory has never accomplished one thing. It has not explained on single phenomena. It has unified nothing. It is one big joke. I know the theory that will replace it, but I am forbidden from posting it here, until said theory is published in a peer-reviewed journal. And so the myth of string theory prevails in this tragic tautology that killed contemporary physics, and the careers of many young physicists--both those who accepted String Theory and those who railed agianst it. Ten years ago I almost went into string theory, but it smelled like a hoax. Too many glossy pictures in the NYT. Too many TV shows. And not one experiment nor solid mathematical principle. So I devoted my years to other ventures. And now it's paying off. Rock on to all the independent thinkers and true physicists, who live in logic, reason and reality! Down with the arrogant postmodern hoaxers and jokesters!!
mcgucken I dont need this kind of noisy announcements and I cant think of anyone else at PF that does we should think carefully about the situation of a lot of talented people, many of them idealistic youngsters wanting to devote their lives to advancing science it's good to have some continue in string because parts of the string program might turn out to work eventually and be very valuable. but some of them (like maybe Gmeiner for instance) are not going to be happy doing string careers because they have higher aspirations. they want to be in a theoretical research line that they think is really going somewhere, and they (some of them) dont think string is. those that feel trapped and frustrated in string should find ways out. and those who believe in its promise and are highly motivated can keep on. what your crowing sounds like is "schadenfreude" which doesnt do anyone any good.
Marcus! Please do not misunderstand me. I have a huge concern for young physicists, scientists, and intellectual entrepreneuers. That is why I am sounding off. I'm a little bit embarassed for all us physicists that String Theory has come to claim such a prominent role in the public's eye, when it is nothing more than a hoax, supported by neither math, physics, nor reality. I just want to let rising physicists know that more important than getting that postdoc or writing that grant proposal for the tenured String Theorist is sticking with logic and reason. I'm just trying to keep them from joining the Ponzi scheme. You can always do theory from outside the academy--in fact it is often better out there--think of Einstein and Bell. A lot of prominent physicicists agree with this. I'll quote them at your request. One of the funniest things is that nobody knows what "M" stands for in "M" theory! They're laughing at us!
touché, and very true it is for I do love a bit of malarky now and then if we keep it light, the talk will be all right actually we are very fortunate to be at a time in physics history when there are big shifts under way (big changes in thinking which we may not even be fully aware of) it is fun to watch I have to go and do some reading and get lunch, back later
String theory, as it stands, is incomplete String theory incorporates some accurate ideas; such as: seminal energy that is manifested as vibrating (actually, complex oscillating) strings. However, fundamentally, string theory incorporates, or attempts to explain, the irreconcilable theories of conventional physics’ standard models, which have proven to be incorrect except under specific conditions. Simply put, the standard models in their present form are contrived; and no fundamental theory, as string theory claims to be, can be expected to integrate them. String theory is correct in assuming that an infinite source of energy manifests as oscillations and emanates from beyond Reality (and. also . . . so returns to this source). These oscillations, which are complex amalgams of slide, swing, and vibration, must be defined mathematically so that they incorporate all the observed properties of reality, which are properties that can be mathematically expressed. A starting point, which should not be too difficult, would be to consider the geometry and source that would, together, describe the genesis of these complex oscillations and their etiology as they morph to mass. Regarding “M”: I think of “M” as standing for Many theories. I know of others that consider “M” standing for Membrane or Multi-dimensional. I believe the final word should go to Paul Townsend.
Hum, mathematicians do not opine the same, in fact many mathematical work in string theory is not rigorous (e.g. conjetures)! In fact, the only great contribution to math was Witten (Fields Medals awarded) work, but contrary to popular myth, it was mainly based in previous Witten work in QFT, differential geometry, and supersymmetric quantum mechanics. That is, was not a pure contribution from string theory to math.
Not so, we had a policy change that took effect on July 15. It was announced here and the result is here.
While much of the work of interest to mathematicians came from TQFT and Supersymmetric ideas in differential geometry, at least some comes from pure String theory. Not all of these are due to Witten. Considerable work and understanding of Calabi Yau's topological features have been made possible somewhat miraculously through String theory. Also, relevance in problem solving w.r.t to noncommutative geometry and twistor theory --> Gauge theory seem to pop up here and there. I have no idea about the theories ultimate physical significance, but I do thing there is something rather deep involved in the mathematics going on, and the really bizarre coincidences and dualities that mysteriously emerge. For that reason, ST will remain an active mathematical subject.
sounds like thoughtful balanced judgement Haelfix and some of your brief comment on other subjects at PF have stood the test of time (the couple of years or so I have been listening) plus this is roughly in line with what i hear other knowledgeable people saying---namely that as physics it might or might not be a dead end, but as mathematics it evidently is not. You mention a couple of other physics lines that have enriched mathematics as well: topological quantum field theory and supersymmetry in differential geometry.