Any actual physicists here able to comment on this?


duncan_bayne

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Is It Time to Embrace Unverified Theories?

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In other words, some scientists are calling for new rules of the game. They’re asking the community to put as much faith in math as they historically have in evidence.

The challenge arises from two ideas prominent in modern theoretical physics. The first is string theory, in which small, vibrating strings make up subatomic particles such as protons and electrons.* The second is the so-called multiverse, which postulates that the Big Bang created not just one universe, but instead an infinite array of universes. Both ideas are beautiful; neither can, as far as we know, be tested.

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This seems quite unreasonable to me, but then I'm not a professional scientist. From the article:

What if that gap becomes infinite? Many physicists fear that string theory and the multiverse might in practice never be observable.

What is the point of a theory of physics that has no observable consequences? Surely this is just mental masturbation? If there are no observable consequences one might as well posit that a unicorn sculpted the multiverse from fairy dust.

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This seems quite unreasonable to me, but then I'm not a professional scientist.

[....]

What is the point of a theory of physics that has no observable consequences? Surely this is just mental masturbation? If there are no observable consequences one might as well posit that a unicorn sculpted the multiverse from fairy dust.

Duncan,

I agree regarding the unreasonableness, and there are physicists who think that string theory and multiuniverse theories aren't properly physics. My husband is one of those physicists.

Here are a couple books you could consult:

The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next by Lee Smolin;

Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law by Peter Woit.

I haven't read either book. However, I know that both books have gotten favorable attention from physicists who don't buy the departure of physics theory from testability.

Ellen

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Duncan, I also agree it is incorrect that not-testable theories proposed on scientific questions may rightly be accepted as true or good enough truth. That bogus suggestion by "some scientists" will never really fly in physics. The article you linked is nice, with its contributions from Woit and from Albert.

I compile tests of general relativity here. One thing kept on test is the fundamental assumption of the equivalence of inertial and gravitational mass. String theory in application to GR and QFT predicts a deviation from that perfect equivalence, if I understand correctly.* Mathematics of string theory has turned out to have some other physical applications, as I have listed in another thread, beginning with this post. But back to the unification of general relativity and quantum field theory: if an alternative to string theory (such as the quantum loop gravity approach) not only unifies and explains theoretically, but receives some experimental support, then it will be universally regarded in physics as superior to a string theory that has never been subjected to any experimental challenge. I know even less about the multiverse work than string theory work, but the preceding sentence applies to it as well.

The preceding books mentioned by Ellen are good quality I’d bet pretty sure, given the authors. October 2, 2015 is the centennial of Einstein’s paper launching general relativity. In the school year 1979-80, I was in graduate physics a while at the University of Chicago. It was the centennial of Einstein’s birth, and we had some special celebration lectures; Bondi and Penrose came over as speakers. One day in our relativity group over at Fermi Institute, while the profs were away, the most horrible, painful argument broke out between two brilliant post-docs over the pursuit of string-theory approaches to quantum gravity. One man was the one giving the talk in my first link above; he was the string theory side. The other was an Indian student of Chandra’s whose name I no longer recall, but whose outlook, and likely his own work, was on the more traditional loop quantum gravity side, such as the line of work by Ashtekar. My own enthusiasm at the time was for Penrose’s twistor approach. All these lines of work continue these many years later, and tests of GR conceived decades ago continue to finally come to fruition. This is all taking a very long time, but these are minds who know what they are doing and the short tasks and the long arc, and I think Albert’s counsel in Duncan’s link is right.

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Channeling Feynman: nope. I can't connect with him. I'd try Einstein, but they removed his brain after he died.

--Brant

I guess that's better than removing it before he died, as was clearly the case with a few professional academics I've worked with.

(The minority, for what it's worth).

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