Quote of the Month
I think there is a widespread misconception that there are many ignored alternatives. I think that most good string theorists would be eager to look into alternatives IF it had even *some* of the good features of a fundamental theory. But most people don’t seem to realize how difficult it is to come up with even a mildly promising alternative. It is not like there are tons of alternatives out there and theorists are ignoring them.
Somebody at Not Even Wrong
posted by Kea | 10:29 AM
10 Comments:
Yes, that's the depressing reality of how string theorists see themselves, as the sole brave sailors on an otherwise deserted sea! I wrote a comment which replied to that, but Dr Woit deleted it. 'Somebody' (a string theory defender) wrote:
'... almost all the ideas that seemed promising, seem to arise naturally in string theory. Supergravity, kaluza-klein theories, etc. were separate ideas initially, but they arise automatically in string theory.'
These people in their own deluded world must somehow see supergravity and kaluza-klein speculations as good ideas, not failures. The ideas connected by string theory are just fashionable speculations which are not even wrong. That they initially 'seemed promising' has nothing to do with science, because of the very long, well-known list of totally misleading ideas that initially 'seemed promising' and became orthodoxy, but then contributed to the censoring of the correct ideas which had to struggle to get attention (flat earth, genesis, epicycles, caloric, phlogiston, etc. ...). Nature is 'subtle', as Einstein observed. The ideas that get immediate limelight aren't always right. This is the problem.
Instead of the fashionably 'even mildly promising alternative' idea being the only one to deserve any attention, it is often the idea that looks unfashionable, and hence less promising to mainstream wags, that is right.
Unfashionable (i.e. new) ideas that are radical, are unfamiliar and often unpromising in their nascent form to the busy mainstream, and are often censored at first, even if they turn out to be correct later on, as the history of science shows.
String theorists define 'promising new ideas' as more uncheckable speculations that link to existing fashionable speculations in string theory. This view of what ‘promising’ means isn’t scientific.
As Tony Smith has pointed out, the problem of fashionable pursuits in physics led Freeman Dyson to declare:
‘... At any particular moment in the history of science, the most important and fruitful ideas are often lying dormant merely because they are unfashionable. Especially in mathematical physics, there is commonly a lag of fifty or a hundred years between the conception of a new idea and its emergence into the maintsream of scientific thought. If this is the time scale of fundamental advance, it follows that anybody doing fundamental work in mathematical physics is almost certain to be unfashionable. ...’
- Dyson’s 1981 essay, Unfashionable Pursuits
The point made is that all alternative ideas radical enough to have any chance of being helpful are also radical enough to be dismissed by today's mainstream.
Dyson is also on video with the example of QED here (Dyson says that leading physicist Oppenheimer at Pocono in 1948 was a 'bigoted old fool' who could not immediately grasp Feynman's path integrals at Pocono in 1948, and instead Oppenheimer kept finding trivial reasons in the wording of the theory to dismiss it as nonsense, trying to prevent any communication of ideas, i.e. to censor Feynman's work). If that could have happened to Feynman, it can happen to any alternative ideas that are radical enough to be useful alternatives!
The best example is of course Feynman's path integral formulation which was dismissed by Teller, Bohr, Dirac and Oppenheimer until Dyson and Bethe eventually won them over at Pocono in 1948.
Tony Smith (this link to a Google cache since his server seems to be down at present), whose new work is now censored from arXiv, has quoted The Beat of a Different Drum: The Life and Sciece of Richard Feynman where Feynman explains that the problem was not just Oppenheimer. Teller dismissed it because it ignored the exclusion principle, Dirac dismissed it because it didn't have a unitary operator, and Bohr dismissed it because he claimed Feynman didn't know the uncertainty principle, and claimed that the uncertainty principle dismissed any notion of path integrals representing the trajectory of an electron! Feynman concluded: 'it didn't make me angry, it just made me realize that ... [ they ] ... didn't know what I was talking about, and it was hopeless to try to explain it further.' Feynman in 1985 in his book QED explained clearly in a footnote that the uncertainty principle is not a separate law from path integrals so Bohr’s objection was invalid; interferences due to random virtual particle exchanges cause the uncertainty.) But if this dismissal from numerous top experts can happen to Feynman's path integrals, it surely can happen to any radical-enough-to-be-helpful quantum gravity ideas!
Another issue with the claim by 'Somebody' at the Not Even Wrong weblog that
'It is not like there are tons of alternatives out there and theorists are ignoring them. ... The self-interest of theorists motivates them to consider new promising ideas very seriously. I don’t even know one promising alternative idea out there which is not getting the attention it deserves.'
is the sheer arrogance of claiming that because 'Somebody' admits to being ignorant of the existence of one promising alternative, this admission of ignorance is somehow to be construed as praiseworthy clever evidence that no such alternative exists! Duh!
It's a bit like Oppenheimer throwing Feynman's paper into the lavatory in 1948, and then stating that he has seen no promising ideas out there. Yeah, right!
Clever political spin trick. If string theory does ever go bankrupt, will its practitioners get jobs in the Ministries of Propaganda for third world dictatorships? How is it that so many people are taken in by this spin?
Dr Woit has written that he thinks that supergravity looks promising, so maybe that's why he deleted my comment. I liked Dr Woit's idea in his 2002 paper that people should be looking to see what kind of gauge group quantum gravity should have, i.e. how do you add to U(1)xSU(2)xSU(3) to include quantum gravity? But, as with Smolin, he is quite proud of mainstream affiliations where it suits him. Neither is radical enough to investigate the full spectrum of promising ideas or back them. For various reasons, they spend time investigating ideas that generate a lot of mathematical speculation but little connection to experiment, i.e. analogies to the failure of string theory.
Out of interest, what do *you* see as viable alternatives to string theory? I'm not a particle theorist so the only ones I'm aware of are loop quantum gravity and twistor theory.
Dear Anonymous. As it happens, one of the main purposes of this blog is to bring attention to alternative ways of working on Quantum Gravity.
Twistor theory is not in itself, nor ever purported to be, a theory of quantum gravity. Rather, it has important lessons to teach us about abstractions of spacetime, but category theory (and other branches of mathematics) take these ideas much further. Loop quantum gravity, on the other hand, simply doesn't work. Many theorists work outside these domains, and outside string theory, for instance in Quantum Information approaches to quantum gravity.
Some of our recent results suggest to us that we might actually be on the right track, and that standard string theory is very wrong (although there are definitely areas of intersection between strings and the things we discuss).
Experience says that those making real advances work out of the limelight.
Kea, can you name some of these alternatives to string theory? (by this I mean theories that unify gravity and the standard model)
Anonymous,
For an example of peer-reviewed published paper unifying U(1) electromagnetism with gravity, see Lunsford's paper Int. J. Theor. Phys. 43 , 1 (2004) 161-177. Lunsford states on the Not Even Wrong blog that this peer-reviewed and published paper was deleted from arXiv.org by the mainstream stringy censors there, effectively preventing any further developments or discussions of that theory in the 'proper' places! This is what happens in the mainstream string theory culture! It's inevitable that since string theory fails to achieve anything real, it must defend itself instead by censoring out alternative ideas and stagnating the rest of the field so it stands out as being alone. (Sinking all the other ships with torpedos, and then claiming to be the only people brave enough to set sail!)
But this is just one example and Kea is doing research into quantum gravity using category theory which is another direction. Such work is usually ignored by the mainstream, or where it is not ignored, it is generally dismissed as unfashionable, or claimed to be wrong by people who don't understand it.
Nige, that paper by Lunsford appears to me to be a unification of classical GR and EM (along the lines of Kaluza-Klein). I'm asking about viable alternatives to string theory, that is, theories that aim to unify gravity and the standard model.
Anonymous, the problem is that these things take too long to explain. Right now we're too busy working out the details of the CKM matrix to deal with educating you, especially given that the result is not likely to be good. The bread crumbs are out there and you can go look for them if you wish. If you have a physics question, we will try harder to answer it.
To Anonymous eager to find viable alternatives to string theory. If you are really seriously interested and have patience to study my homepage, you might learn such an alternative has existed for a long time (the politician inside me suggests to add ;-) here to avoid crackpot label but I have no reason to pretend that I am joking).
For instance, the chapter Configuration Space Spinor Structure in one of the books gives reasonably good overview about basic ideas. There are also articles besides the 7 books devoted to TGD and 8 books devoted to TGD inspired theory of consciousness and quantum biology.
TGD was born around 1977 and can be seen either as a generalization of string model by replacing strings with 3-D surfaces or as a manner to construct Poincare invariant theory of gravitation. The basic assumption is that space-times are surfaces in 8-D space M^4xCP_2. The choice fixed by standard model symmetries.
Some remarks about the relationship to string model are in order.
It is now clear that TGD allows a dimensional reduction to a string model like theory. The naive expectation that gravitational constant would directly correspond to string tension is however incorrect.
One basic distinction from string model is that spontaneous compactification is replaced with what might be called number theoretical compactification stating that one can regard space-time surface either as surfaces in M^8 regarded as hyper-octonionic space or in H=M^4xCP_2. This is not an actual compactification but just a duality between equivalent descriptions and I call it M^8-H duality. There is no landscape problem and standard model symmetries have purely number theoretical interpretation.
Second difference relates to the realization super conformal symmetries: super space concept and Majorana condition are not needed since the anticommutators of superconfromal charges give Hamiltonians rather than vector fields of bosonic symmetries. Therefore super charges carry lepton and quark numbers and subset of them defines gamma matrices of the configuration space (the space of light-like 3-surfaces, "world of classical worlds"). No spartners are predicted.
Further difference is that light-like 3-surfaces realized the super conformal symmetries by their metric 2-dimensionality. This realization of superconformal symmetries works only for space-time dimension D=4.
To go further would require more background.
Matti Pitkanen
Anonymous on 2/10:
The W in the variational principle can be replaced by the general Yang-Mills FmnFmn, and so it is a unification of any Yang-Mills field and gravity. I just did it explicitly for U(1).
This then is an alternative that should be studied, but will not be of course. It is not a lack of alternatives, but humility, that impedes progress.
-drl
Post a Comment
<< Home