Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> Warp wrote:
>>>   Time must exist, or else it would be impossible to postulate essential
>>> properties of physics such as the second law of thermodynamics. 
> 
>> The second law is statistical.
> 
>   It still states that the entropy of an isolated system never decreases.

But that's wrong. It's just very, very unlikely to decrease.

Are you saying it's literally impossible to take a random deck of cards and 
shuffle it and wind up with it in order?

>>> You can unambiguously distinguish if a closed system is going forward in
>>> time by measuring its entropy.)
> 
>> No you can't, because time is reversible.
> 
>   That would mean that entropy is also reversible, which would break the
> second law.

No, it means that entropy is a statistical property.

>> Note that QM has no arrow of time. Reactions going forward are identical 
>> (altho inverted) to reactions going backwards.
> 
>   The sourced wikipedia text seems to disagree with that assessment.

http://en.wikipedia.org/wiki/Arrow_of_time

There are lots of "arrows of time". That's the problem.

> "For isolated systems, entropy never decreases. 

This is simply untrue. Entropy is a statistical property, just like the 
electrostatic "force" is.

>>>   Space must exist, or else it would be impossible to postulate essential
>>> properties of physics, such as the Pauli exclusion principle. 
> 
>> The Pauli exclusion principle is not part of GR. It's part of QM. :-)
> 
>   How does that change the claim "space must exist"?

I was saying that you're arguing that in GR space must exist, and using QM 
to prove it, and those are incompatible theories.

>   If you accept the Pauli exclusion principle as one of the fundamental
> laws of nature, then you have to accept space existing (or explain the
> law in question in the case that space does not really exist).

And if you accept general relativity and the identity of acceleration and 
gravity, you have to throw away space as existing.

That's my point. I'm not saying "space doesn't exist."  I'm saying 
"physicists are unable to determine yet if space exists, and that's what the 
GUT is supposed to determine. Does space exist as a separate thing, or is it 
just information?"

I'm saying "it's still up in the air", and you're trying to disprove by 
picking half the arguments that the other half are wrong.

>   Even if spacetime couldn't exist without energy, does that mean that
> spacetime *is* energy?

My understanding is that this is saying that spacetime is the relationship 
between pieces of energy. So space is "information", in some sense.

-- 
Darren New, San Diego CA, USA (PST)
   Serving Suggestion:
     "Don't serve this any more. It's awful."

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