ThomasT said:
Intriguing.Careful said:
And, my guess is that it isn't. I start by assuming that there's a fundamental (wave evolution) dynamic. Sort of a cellular automata approach except that there are no 'cells' to begin with. Just a seamless, homogenous, isotropic medium with some 'disturbances' introduced. There are no original organizational or survival rules other than the fundamental wave dynamic. Some interesting 'creatures' have emerged, as have some higher order organizing principles, or dynamics.Careful said:
Are you then not getting into trouble with relativity? Moreover, one would expect generically to get out the wrong S-matrix since many amplitudes of different scattering processes are connected by time symmetry. How do you explain that? The point of my line of thought is that it is consistent with observations, yours *might* get into trouble fairly quickly.ThomasT said:
It's just a fundamental wave dynamic allowed to iterate in a medium. The principles (and constraints) of relativity don't really apply. There are no internal observers. It's a 'birds eye' view. Propagational speed is limited by the computer's processing power.Careful said:
S-matrix doesn't apply.Careful said:
Careful said:
Well, so are my fundamental conceptual assumptions "consistent with observations", but so far all I can say is that I still don't know if it's a good approach to understanding our universe, nature, reality.? What do you mean by the principles of relativity don't really apply?? They are the most sacred principles of modern physics. Well, it might be that your theory does not contain an S matrix at the fundamental level, that's perfectly ok (I would say it is even good), but still you would need to retrieve the standard S-matrix to a good approximation. THAT's what I was asking for.ThomasT said:It's just a fundamental wave dynamic allowed to iterate in a medium. The principles (and constraints) of relativity don't really apply. There are no internal observers. It's a 'birds eye' view. Propagational speed is limited by the computer's processing power.
S-matrix doesn't apply.
No internal observers. No relativity principles necessary.Careful said:
Yes, because modern physics is conducted by internal observers.Careful said:
It isn't an exercise in constructing a physically viable mathematical theory. It's an exercise in understanding what sorts of particulate regimes, persistent bounded wave structures, etc. might emerge from a single fundamental wave dynamic.Careful said:
No I don't agree, there is experimental support for the idea from elementary particle physics (at those scales!). There are however, contra-indications coming from macro-physics (whether, it is a fundamental issue or not at *those* scales, I would say, might a matter of taste so far).ThomasT said:
For what idea? That the experimental evolutions are time-symmetric, or that some aspect of the formalism describing the experiments is invariant wrt time reversal?Careful said:
Contra-indications to what coming from macrophysics? The time-asymmetry of macrophysical phenomena?Careful said:
I was thinking about this statement some more. Actually I don't think that it is consistent with observations. As far as I know, all 'observations' indicate time asymmetry. But I'm quite open to being corrected on this.Careful said:
Ok, at this point we should say *exactly* what we mean; people mean usually several things with time-reversal invariance. What I mean (and that is the only sensible point of view) is that time-reversal invariance simply means you are working with a Hamiltonian system where H does not explicitely depend upon time. You might work with an explicit time dependent H or like Prigogine did generalize away to nonholonomic mechanics (there exists no energy whatsoever). It seems that both these options have to satisfy severe constraints in order to agree with experiment (which does not mean that I think they are wrong). Another thing people might mean is that you work with a conventional time independent Hamiltonian and then, we know that the CPT theorem has to hold to high accuracy (because gravity is weak). In this framework, the anti-unitary T operator is known not to be an exact symmetry but it is only known to be violated very weakly in the weak interactions. So, again, you would face severe difficulties here if you do not start from a Lagrangian framework in which the T violating terms come with small couplings.ThomasT said:
Again, it depends upon what you mean with this (let's clarify it first ok?). When I say that microphysics is to a good degree time symmetric, then I intend to say that the conventional time independent Hamiltonian picture with it's CPT invariance works rather well. For macrophysics, I would agree that it doesn't and what I have in mind approaches better the first two options I mentioned (so the time dependent Hamiltonian and/or Prigogine scheme).ThomasT said:
Ok, this makes sense to me. The problem is that it isn't really an indication (at least certainly not a definitive one) that (sub)microphysical phenomena are time-symmetric.Careful said:
So, I'm wondering, why not apply this approach to (sub)microscopic systems as well?Careful said:
You should not mix two things here: if you would stick to conventional physics as we know it today, then the only explanation for localized entropy increases/decreases I can cook up is by looking at the initial values. People seem to agree that those would have to be rather special to give our macroscopic universe and I agree with amongst others Bob Wald that it is rather pointless to look for dynamical theories which would explain those. So, there really is at the moment no hint for a better explanation and we seem to get lost in anthropic reasoning. On the other hand, if some fundamental assymetry would creep in on the *macroscopic* scale, we have a much better chance at getting there.ThomasT said:
Because it would violate Lorentz invariance. Nobody says that Lorentz invariance has to hold for large objects, because then gravity is dominant and it brakes global Lorentz invariance brutally. However, for tiny things like electrons or photons Lorentz invariance holds to a much higher degree and *might* only get violated at energy scales close to the Planck energy.ThomasT said:
Values are unimportant wrt fundamental dynamics. Values are emergent. Values will be more or less unpredictable.Careful said:
I agree with this. But those 'values' didn't come from nothing, and our universe is 'evolving'.Careful said:
I agree that an understanding wrt a fundamental dynamic(s) will probably not account for specific observed values as currently formulated. And who is Bob Wald?Careful said:
I would tend to agree with this also. But looking for an understanding via a fundamental dynamic(s) is about as far from anthropic reasoning we can get. Don't you think?Careful said:
Sure. That's another reason to look for it, or assume it, at the (sub)microscopic scale.Careful said:
Well, yes. If the aim is to explain certain values, then that will require a value-laden approach. However, if the aim is to 'understand' the emergence of complex, time-asymmetric, evolving systems in general, then a time-asymmetric fundamental (wave?) dynamic(s) would seem to be the approach to take, imho.Careful said:
His stuff is over my head. Probably your stuff (that you are reluctant to reveal) is over my head too. No problem. I've enjoyed our conversation. Anything further that you might want to enlighten me wrt is appreciated. Thanks.This is a good stopping pointThomasT said:OK, that, Bob Wald.
I know why you believe this conclusion is ''unavoidable'' if you insist upon a fundamental time assymetric dynamics at the macroscopic scale. But it really isn't: that is all I have to say.ThomasT said: