No entropy/environment = no time flow?

**Fra** · Nov13-09, 01:29 AM

Originally Posted by dmtr

What I've seen is a few circular definitions. Namely probability defined in terms of probability. Time defined in terms of time. Somewhat murky entropy definitions. The arrow of time referring to the direction of the entropy increase. And of course the 2nd law using all these terms.

-- Dmtr

I'm not sure if I make the right associations to your thinking here, and at what level you picture this, but if you have objections about the use of probability theory and the notion of entropy then I can just add that I have such objections as well.

It is completely true however, that there is no different in principle between QM and classical physics. That however doesn't mean it's more sound, it just means the same unsatisfactory reasoning is used in both places :) This is why the context of which I would want to raise this objection is in the "beyond the standard model" context.

I don't know if this is what Dmtr also means, or not?? but by objection is that from the point of view of (what I personally seek) an intrinsic measurement theory, entropy measures are not uniqe. There are as we know several different definitions of entropy measures. They can be "derived" in severals ways, from cox axioms, or from other considerations. My opinion is that it makes no sense to consider a universally objective information measure. This has been briefly discussed in several threads mainly in the BTSM I think.

There are also some threads here discussing the relatvivity of entropy.

I've question continuum probability theory itself, on the basis thta the continuum notion implies (IMHO at least) an infinitely massive observer - which I think, makes no sense except as an APPROXIMATION (where instead of actually using large numbers, you describe it as a "continuum" - this is fine in the limit, but care must then be taken when you "scale it back" to the small number limit).

/Fredrik

**dmtr** · Nov13-09, 03:45 PM

Originally Posted by Fra

I'm not sure if I make the right associations to your thinking here, and at what level you picture this, but if you have objections about the use of probability theory and the notion of entropy then I can just add that I have such objections as well.

It is completely true however, that there is no different in principle between QM and classical physics. That however doesn't mean it's more sound, it just means the same unsatisfactory reasoning is used in both places :) This is why the context of which I would want to raise this objection is in the "beyond the standard model" context.

I don't know if this is what Dmtr also means, or not?? but by objection is that from the point of view of (what I personally seek) an intrinsic measurement theory, entropy measures are not uniqe. There are as we know several different definitions of entropy measures. They can be "derived" in severals ways, from cox axioms, or from other considerations. My opinion is that it makes no sense to consider a universally objective information measure. This has been briefly discussed in several threads mainly in the BTSM I think.

I have no objections to the use of the probability theory, entropy, or the 2nd law. These are very good instruments. For instance in the QM we can calculate probabilities which very often agree with the experiments very well. And we would be very much surprised if suddenly they wouldn't.

What I don't like however is when these instruments are used to give the ultimate definition of the arrow of time. Use of the 2nd law to define the time arrow makes sense only in the classical approximation, where the 2nd law is defined. It hardly makes sense even there, because time/causality is an axiom in the classical approximation.

An alternative to that is to think of some properties of the quantum state space that would ultimately result in the 2nd law and the familiar time arrow in the classical approximation.

-- Dmtr