Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> And I'm still not convinced you can actually destroy information. At the 
>> quantum level, time is reversible, which means that information at that 
>> level does *not* get destroyed.
> 
>   I don't understand how time could be reversible, because that would imply
> that an increase in entropy (of an isolated system) would also be reversible,
> which is against the law.

Because the law is statistical, and if you get sufficiently few degrees of 
freedom, then the statistics work out such that the probability *does* 
reverse on occasion.

Take a perfect frictionless billiards table. Rack the balls. Throw one ball 
into the middle. Watch them bounce around a while. Will they ever re-rack? 
No, that's entropy.  Is every interaction reversible?  Yes.  Is it 
*possible* the balls will bounce around enough to eventually come back 
together with exactly the right velocities that they'll all rerack? Certainly.

Take a tank of water. Put two atoms of ink in it. Let them diffuse until 
they're one on each side of the tank. Is it possible they'll ever randomly 
come together to where they're both very close to each other at one corner 
of the tank? Sure.  How long before 10^20 selected atoms of ink do that at 
random? A long, long time. Is it impossible? No.

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

Post a reply to this message

bart wrote:
> This is a funny one:
> http://www.huffingtonpost.com/2008/12/03/clever-chicken-hides-out_n_148133.html 

Because obviously the rooster knew he is adorable and the people working at 
McDonalds would take care of him.

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

Post a reply to this message

>> The second law is statistical.
>
>  It still states that the entropy of an isolated system never decreases.

IIRC the derivation/proof of the 2nd law assumes stuff like an infinite 
amount of matter - so the probability of the entropy increasing is (almost) 
zero.

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> >>>   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.

  I never said that in GR space must exist. I said that in this universe
space exists. I don't know why you brought GR into this.

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

  That statement makes absolutely no sense.

-- 
                                                          - Warp

Post a reply to this message

Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>>>>>   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.
> 
>   I never said that in GR space must exist. I said that in this universe
> space exists. I don't know why you brought GR into this.

Well, I was talking about GR saying that space doesn't exist, and you said 
QM says space must exist.

But note that the Pauli exclusion principle doesn't mean space must exist. 
It means distance must exist. We already know that distance must exist. We 
don't know whether there's some underlying substrate (space) that makes 
distance exist even if there's no matter present.

>> And if you accept general relativity and the identity of acceleration and 
>> gravity, you have to throw away space as existing.
> 
>   That statement makes absolutely no sense.

Or, to phrase it differently, my understanding is that GR says that distance 
exists, but not space. If there's nothing to have distance between, there 
wouldn't be space.  When you make measurements, you're not measuring 
*against* something.  You don't say "this item is three units of space away 
from that one", you can only say "it's twice as far from that one as it is 
from the other."  That, I think, is what "background-free" means. There are 
no free variables in the equations that would represent space - they're all 
tied to positions of particles, which is why space is relative.

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

Post a reply to this message

On 11/2/2010 6:56 PM, Darren New wrote:
> Warp wrote:
>> For one, timespace, ie. the geometry of the Universe is not energy.
>> It's the "container" where the energy in the Universe resides, in other
>> words it *contains* energy, it's not energy in itself.
>
> I don't think science has determined this. GR is background-free, so in
> a sense, space-time is a relationship between other things and nothing
> more. It's not a "something" but an effect.

It could also be that what we experience (or measure, to be more 
precise) as particles (photons, neutrons, etc.) are really just wrinkles 
in space-time.  The book _Flatland_ comes to mind for some reason.

>> (Another point which would indicate that information is not
>> energy is that energy cannot be created nor destroyed, but information
>> can.)
>
> Actually, there's good reason to think information cannot be destroyed.
> That's what lead to postulating the holographic principle and hawking
> radiation. The basic problem is that the QM theories preserve certain
> kinds of information that GR does not, so matter falling into a black
> hole violates quantum mechanics in a very fundamental way.

The notion of a black hole being a singularity is probably a violation 
of QM, although I am inclined to believe that this is not the case.  But 
the fact that information cannot be retrieved (as from a black hole, 
once the media has passed within the event horizon) by no means implies 
that the information is destroyed.  Sort of like my personnel records in 
the military.  For a brief time nobody could find them, but they still 
existed.

Regards,
John

Post a reply to this message

John VanSickle <evi### [at] hotmailcom> wrote:
> The notion of a black hole being a singularity is probably a violation 
> of QM, although I am inclined to believe that this is not the case.  But 
> the fact that information cannot be retrieved (as from a black hole, 
> once the media has passed within the event horizon) by no means implies 
> that the information is destroyed.  Sort of like my personnel records in 
> the military.  For a brief time nobody could find them, but they still 
> existed.

  The so-called "no-hair theorem" is related to exactly that:
http://en.wikipedia.org/wiki/No-hair_theorem

  Famously Stephen Hawking lost a bet because of changing his opinion on
whether the information is permanently lost in a black hole or not.
http://en.wikipedia.org/wiki/Thorne%E2%80%93Hawking%E2%80%93Preskill_bet

-- 
                                                          - Warp

Post a reply to this message

John VanSickle wrote:
> It could also be that what we experience (or measure, to be more 
> precise) as particles (photons, neutrons, etc.) are really just wrinkles 
> in space-time.  The book _Flatland_ comes to mind for some reason.

They are, basically. :-) That's what mass is: a wrinkle in spacetime.

> by no means implies that the information is destroyed. 

Except it does. What's the quantum spin of a black hole? How can you tell?

The problem is not that it falls into a black hole. We can still tell the 
mass and charge and angular momentum of everything that has fallen into a 
black hole. But the things you can't measure, like some of the quantum 
properties like color and spin, those get destroyed.

At least, as I understand it.

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

Post a reply to this message

John VanSickle <evi### [at] hotmailcom> wrote:
> It could also be that what we experience (or measure, to be more
> precise) as particles (photons, neutrons, etc.) are really just wrinkles
> in space-time.

the Universe is truly terribly old after all... :)

Post a reply to this message

On 11/4/2010 3:54 PM, Darren New wrote:
> Patrick Elliott wrote:
>> Bad one I think. Sound, etc. isn't made up of air, water, or whatever.
>> It would be more accurate to say that it is made up of what those
>> things are "doing". This is not *that* different than words on a page.
>
> Yep. And the point is that (as I understand it) according to GR,
> spacetime is made up out of what energy is doing. You got it on the
> first try.
>
> There's nothing in the universe except energy, and everything else
> (force, space, time, etc) is just what energy is doing.
>
> Whether you want to argue that means there *is* something besides energy
> is arguing over whether sound *is* something besides the atoms and their
> behavior.
>
Want a lovely GR thing.. Some experiments are.. attempting to be 
constructed, I suppose you might say, since there is a thought that they 
simply won't work at all, which will attempt to determine if you can 
build the equivalent of a gravitational transformer. GR implies yes, 
since for example, the clocks on a satellite do not "run" at the same 
rate as their ground based systems, they are effected differently by the 
speed, and level of gravity, in orbit. So.. the idea is to use one 
gravitational effect to generate a field, which would *cause* a 
gravitational effect in something else, in principle, similar to the 
change in frequency and the like you get in an electrical transformer.

The problem being, it may simply not work, even if GR says it should, 
and some effects imply that it happens, to an extent, already, just not 
on what might be called a practical scale.

-- 
void main () {
   If Schrödingers_cat is alive or version > 98 {
     if version = "Vista" {
       call slow_by_half();
       call DRM_everything();
     }
     call functional_code();
   }
   else
     call crash_windows();
}

<A HREF='http://www.daz3d.com/index.php?refid=16130551'>Get 3D Models, 
3D Content, and 3D Software at DAZ3D!</A>

Post a reply to this message