Supersymmetry people always argue that it can help to unify the coupling constants of the strong weak and electromagnetic interactions; they come together to a single value at 10^16 GeV. That is an argument for supersymmetry, they claim.
But wait. Why should the coupling constant reach a single value? After all, the coupling constants of the electromagnetic and the weak interaction do not reach the same value, and still the two interactions unify.
So we do not need the same coupling constant value for unification? Agreed. But then we do not have an argument for supersymmetry any more? Agreed. But then supersymmetry people are telling nonsense? Agreed. As a check for the last conclusion, ask your favorite supersymmetry expert the following question. At energies higher than 10^16 GeV, the three coupling constants separate again; are the interactions not unified any more at higher energies?
You will get answers like: "We do not know what happens there." So the supersymmetry people who propagate the argument that unification requires a single coupling constant are people who tell us that we know what happens at 10^16 GeV, or
10000000000000000 eV,
but we do not know what happens at 10^16 GeV plus 1 eV, or
10000000000000001 eV.
These people can calculate integrals in fermionic space (which does not exist) but are unable of simple logic (which does exist). Supersymmetry "experts" are really hilarious.
I looked on Wikipedia, and it said one reason supersymmetry was explored was because it could give some new symmetry groups. But if the Strand Model is right, and the existing symmetry groups are just the result of the three basic ways of making tangles -- twisting a strand, U(1), poking one strand over another, SU(2), and sliding a strand over a crossing in another two SU(3) -- then there is no reason to expect any new symmetry groups.
ReplyDeleteHow can anybody not be intrigued by that?
The argument of these three ways is not convincing, I guess.
DeleteOne time, I was trying to find out what these SU(n) thingies were, and I read that SU(2) is a double covering of SO(3) and that SO(3) is just the pattern of what happens when you combine different rotations in 3 dimensions. Well I don't know what a double covering is, but I do know about rotations in 3D: the order you do them in can affect the final orientation of the thing you are rotating.
DeleteThe weak nuclear force is just the transfer of a poke in two strands into the strand of some other tangle, it says in Motion Mountain, vol.6, p228. And it says you can make a poke by rotating a circular piece of card which is stuck across two parallel strands (in different words, though) by rotating it about any of three perpendicular axes. OK so we're just doing rotations in 3D (so SO(3) should apply, and maybe SU(2) as well -- but I don't understand what a double covering is).
Well at first, the only axis that I could get to make a poke (in my headphone cable with a bit of card stuck to it) was the axis parallel to the strands. Eventually I noticed I could get a poke using the axis that crosses the strands if at the same time as rotating the card, I also moved the card along the axis a bit, in either direction. But for the rotation where you keep the card flat and just turn it around like a disc, depending on how the strands flopped, I either got zero, one, or two pokes.
Then I remembered something about in physics, the SU(3) symmetry you get for strong nuclear force is an exact symmetry, but the SU(2) symmetry of the weak nuclear force isn't exact; it's only approximate. Is that the reason for my difficulty making the pokes, or have I just been going wrong? (Sorry for being a bit thick.)
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ReplyDeleteFor SU(2), all you say should be true. I think the strands have to "flop" correctly, as you write. But for SU(3) ...
ReplyDeleteThanks, Clara, for the reassurance. Yes, for SU(3), I haven't had a proper go yet. I had a look through it and thought 'Ooh blimely! This looks a bit hard'.
DeleteFirst I saw all those gluon tangles in Fig.63, p240, and there were nine instead of eight, in three groups of three, but that's all right -- under one it says only two are linearly independent (but then my head started to throb, trying to work out how). Then I see the strong force is a combination of a rotation and a slide, not just a slide -- because a slide on its own doesn't involve any crossing switches. Well, OK. And then down the left-hand side of Fig.65, I can see how the 3 types of rotation-and-slide are done, but then it all gets a bit challenging.
I don't think my headphone cable is going to suffice this time. I'll have to have a root through my cupboards for some belts. It looks like I need three. So what I have to do is fiddle around with 3 belts and satisfy myself that the patterns I get are the patterns of SU(3). That could be tough -- I've only got the very haziest notion of what SU(3) is.
Jumping down ahead a bit, I see 'the 3 colour charges are the three possibilities to map a tangle to the three-belt model', p246, and 'the strong interaction is due to the exchange of slides', p247.
OK so I can see how it could be that it all works out, but actually satisfying myself that it does in fact all work out could be a bit above my level I guess.
Anonymous,
ReplyDeleteyou remind me that I should also give it a go. Let's exchange impressions.