Jesse Mazer wrote:
As for the question of why we live in a universe that apparently has this
property, I don't think there's an anthropic explanation for it, I'd see
it
as part of the larger question of why we live in a universe whose
fundamental laws seem to be so elegant and posess so
Ti Bo wrote:
On reversibility, there is the observation (I think acredittable to Tom
Toffoli)
that most/all irreversible systems have a reversible subsystem and the
dynamics arrive in that
subsystem after some (finite) time. Thus any system that we observe a
while
after it has started
Saibal Mitra wrote:
How would an observer know he is living in a universe in which information
is lost? Information loss means that time evolution can map two different
initial states to the same final state. The observer in the final state
thus
cannot know that information really has been
From: Wei Dai [EMAIL PROTECTED]
Reply-To: everything-list@googlegroups.com
To: everything-list@googlegroups.com
Subject: Re: why can't we erase information?
Date: Mon, 10 Apr 2006 16:11:28 -0700
Jesse Mazer wrote:
As for the question of why we live in a universe that apparently has
this
Hi All,
I feel like a Toffoli disciple. I cannot recreate the argument right
now,
but he argues that an increase in entropy is compatible with reversible
and irreversible
processes, but a decrease in entropy is only compatible with reversible
dynamics.
The argument is interesting and
I think that this observation could explain why we see a reversible
universe:
all the irreversibility has already happened. If we think of a dynamics
with
discrete time then we have a collection of points with directed arcs
between them. As a graph, this has the structure of several cycles
Jesse Mazer:
I have a vague memory that there was some result showing the algorithmic
complexity of a string shouldn't depend too strongly on the details of the
Turing machine--that it would only differ by some constant amount for any
two different machines, maybe? Does this ring a bell with
Yes, I agree. But it could be that information loss is a bit ambiguous. E.g.
't Hooft has shown that you can start with a deterministic model exhibiting
information loss and end up with quantum mechanics.
Saibal
- Original Message -
From: Jesse Mazer [EMAIL PROTECTED]
To:
Le 11-avr.-06, à 01:11, Wei Dai a écrit :
Jesse Mazer wrote:
As for the question of why we live in a universe that apparently has
this
property, I don't think there's an anthropic explanation for it, I'd
see
it
as part of the larger question of why we live in a universe whose
Le 11-avr.-06, à 00:19, John M a écrit :
Comp? I always considered it the - so far - best ways
the human mind could invent for reductionist thinking.
I am too busy this week to comment this delicate point. I will explain
later some basic think in computer science which are needed, not only
- Original Message -
From: Wei Dai [EMAIL PROTECTED]
To: everything-list@googlegroups.com
Sent: Tuesday, April 11, 2006 01:46 AM
Subject: Re: why can't we erase information?
Saibal Mitra wrote:
How would an observer know he is living in a universe in which
information
is lost?
I'm not a physicist, so I'm asking a question. How much of this we
have no information loss in this universe prinicple are we simply
assuming at the outset? I know that a lot of it is unverified theory,
like in the case of Stephen Hawking's black hole vs. no black hole from
infinity
A few years ago I posted a speculation about Harry Potter universes,
from the Schmidhuber perspective. Schmidhuber argues that the reason
we don't see such a universe is that its program would be more complex,
hence its algorithmic-complexity measure would be less. Such a universe
would
--- Stathis Papaioannou
[EMAIL PROTECTED] wrote:
among others:
*
I understood Tom's phrase atomic parts as meaning
component parts rather
than literally what scientists call atoms
fine, I used Tom's word. It went to a nice extreme.
*
Then about 'rules':
It was deliberately left
On Mon, Apr 10, 2006 at 09:45:50PM -0700, Brent Meeker wrote:
Russell Standish wrote:
On Mon, Apr 10, 2006 at 12:03:47AM -0700, Brent Meeker wrote:
Russell Standish wrote:
Unitary evolution preserves information. It is only through
measurement by an observer that information can be
On Mon, Apr 10, 2006 at 10:26:17PM -0400, Jesse Mazer wrote:
As I understand it, you don't need exactly need an observer, you just need
to identify various macro-variables (like pressure and temperature) which
can be used to coarse-grain the phase space of the system, with entropy
being
There would have to be some pretty major conditions and caveats on
this. A system undergoing thermodynamic stress (ie is nonequilibrium)
will exhibit a lowering of entropy compared with its state at
equilibrium. However, the process is decidedly nonreversible...
Cheers.
On Tue, Apr 11, 2006 at
Russell Standish wrote:
Also note that exact measurements of microstates is *in principle*
incompatible with the Heisenberg Uncertainty Principle.
Well, that's why I defined microstates as detailed descriptions of the
positions and momenta of all the particles, within the limits of the
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