Cosmologic philosophy: multiverse/string theory (Introduction)

by David Turell , Wednesday, December 30, 2015, 15:11 (3251 days ago) @ David Turell

Peter Woit, a strong critic of string theory reviews a new book, Why String Theory?, favorably, as the book admits the theory is not testable:-http://www.math.columbia.edu/~woit/wordpress/?p=8214-"The book is explicitly motivated by the desire to answer a lot of the criticism of string theory that has become rather widespread in recent years (wasn't always so…). For a typical example from the last few days, see Why String Theory is Not a Scientific Theory at Starts With a Bang. I have mixed feelings about this sort of thing. It gets the main point quite right, that string theory unification is untestable, having failed to make any predictions, and by the conventional understanding of the scientific method, it's past the time at which most theorists should have abandoned it and moved on. On the other hand, I don't see at all the point to arguing about the term “scientific theory”. Sure, it's a scientific theory, a failed one. I've personally never noticed any consistent usage by physicists of terms like “theory”, “model” and “hypothesis” in ways that accurately indicate degree of experimental support, don't see why some writers insist that there is one. I also very strongly object to the article's standard move of trying to make a failed theory a “mathematical theory”. Mathematics is about well-defined ideas, and there is currently no such mathematical construct as “string theory”. The problems with string theory have nothing do with mathematics, rather have to do with a physical idea that didn't work out.-***-
"The most serious problem with the anthropic landscape is that it provides a cheap and lazy explanation that does not come from hard calculation and also has no clear experimental test. It sounds exciting, but does not offer lasting sustenance, and may even act as a deterrent against necessary hard work developing new calculational tools.- "Of course, this does no mean that the anthropic approach is necessarily wrong. However the triumph of science has been not because it contains ideas that are not necessarily wrong, but because it contains ideas that are, in some important sense, known to be true: ideas which have either passed experimental test or are glued together by calculation. The anthropic landscape is neither of these. It represents incontinence of speculation joined to constipation of experiment.-"Instead of Harlow's claims that string theory makes lots of postdictions, coming very close to reproducing the complete standard model, modulo some technical issues, Conlon deals with the situation in a much more honest and straightforward fashion. Of the fourteen chapters of the book, chapter 7 is entitled “Direct Experimental Evidence for String Theory.” Here's the entire content of chapter 7:-"There is no direct experimental evidence for string theory.-***-"Many of his colleagues have adopted the attitude that, while connecting string theory to experiment is hopeless, it deserves investigation purely as an idea about quantum gravity. While Conlon devotes a fair amount of space to the arguments about quantum gravity and string theory claims about them (including some criticism of loop quantum gravity) he avoids much of the usual hype, and also makes it clear that he himself isn't interested in pursuing this because of the lack of any hope of ever testing one's ideas. In some sense I think he and I agree here: it is only if one's idea for quantizing space-time degree of freedom connects up somehow to our successful theories of other quantized degrees of freedom that one will have any hope of ever knowing whether one has the right theory of quantum gravity. Absent a connection of this kind, one is doomed to become just another cog in an endless fruitless ideological argument about whose quantum theory of gravity is better (or at least, whose sucks less)."-Comment: There are cracks appearing ion the façade of string theory.