It Really is "Turtles all the Way Down".

[Gord_in_Toronto]

It's all good Zeggman. As I said, your replies after the first post on this tread seem to point in a different direction.

We get lots and lots of crazies here based on the site so I think the regulars around here (myself included although I tend to lurk more than post) are quick to jump the gun when something looks a little out of left field. If you stick around for a while you will start to see a pattern to the crazy.



Again, welcome to the forum.

Seconded.

 

[Cuddles]

That abstract sets off all sorts of crank alarm bells. He's claiming including torsion magically solves at least five of the biggest problems in physics.

No, he's claiming that torsion completely non-magically solves, or at least may have the potential to solve, some of the biggest problems in physics. Just as people claim might be the case for string theory, M-theory, super-symmetry, MOND and so on. That's pretty much the entire reason people study these things in the first place. If they didn't have at least the hope of solving these problems, why would anyone bother with them? Obviously most, if not all, will fail to live up to that hope, but it's rather silly to dismiss them simply because they dare to try to fix the problems with existing theories.

Note that this (torsion and related extensions of general relativity) is something that people have been studying for the last 100 years, without it ever catching on or getting much attention.

So? Either it works or it doesn't. If you want to criticise it based on the actual science and maths, go ahead. Claiming its crank stuff based solely on an argument to popularity really isn't going to cut it.

If torsion is non-zero, experiment constrains it to be very small. See here for instance. What I said about black holes and the universe applies to the universe today, when the average energy density is low and the effects of torsion (given those constraints) are totally negligible.

No. If torsion is non-zero, experiment constrains it to be very small, and only be significant under extreme conditions such as the densities inside a black hole or during the early universe. Which, as I already pointed out, is exactly the areas the claims are being made about. It's even explicitly stated in the abstract you just dismissed out of hand:

I will also demonstrate that this scenario explains why the Universe today appears spatially flat, homogeneous and isotropic

You're not coming up with some obvious gotcha here. Your criticism is a point he specifically addresses, so merely mentioning that it's a potential problem is hardly useful. Why don't you try reading the actual papers and tell us where you find an actual problem in them?

Note that I don't actually have a horse in this race. It's not an area I've encountered much before and I've only skimmed over a few of the papers rather than reading about it in depth. It's just that appears to be a lot more than anyone else here has done, and people seem weirdly eager to dismiss it all out of hand rather than actually learn about a potentially interesting bit of theoretical physics.

 

[sol invictus]

No, he's claiming that torsion completely non-magically solves, or at least may have the potential to solve, some of the biggest problems in physics. Just as people claim might be the case for string theory, M-theory, super-symmetry, MOND and so on.

Yes - but torsion has been around since the beginning of GR and is very well understood, by contrast to the newer, far more complex and sophisticated theories and ideas you mention. Why is he the only person out of all those that have studied it that believe it's going to solve all those problems?

Including torsion is equivalent to changing the classical theory of gravity. We know the world is quantum, and the hard problems in fundamental physics are essentially all associated with how quantum mechanics and gravity come together.

The real problem with his ideas is that if the torsion terms are as small as experiment tells us they must be, they are only important at densities and energies where quantum gravity effects are also important. But we have very little knowledge or control over such effects, other than to say that they are almost certainly there. So adding torsion into the mix is pretty much meaningless.

As for the black hole/Hubble radius/universe's average density thing, that was in response to the OP ("I remember reading an article in ISTR a science fiction magazine that claimed the the Universe was a Black Hole because it was of the right density to be one..."). That applies today, in the current universe where the density is very low and torsion totally negligible.