On 08 Nov 2014, at 22:46, John Clark wrote:
On Sat, Nov 8, 2014 Alberto G. Corona <agocor...@gmail.com> wrote:
> The arrow of time is defined by the increase of entropy
No, increasing entropy is not sufficient to establish a arrow of
time, as I've said it can explain why Entropy will be higher
tomorrow but by using the exact same logic Entropy should have been
higher yesterday than today too, but clearly that is nonsense.
To see how that is true consider all the logically possible
microstates of Alberto Corona that would produce the macrostate that
both you and I would recognize as Alberto Corona, the vast majority
of those microstates must have evolved from high entropy states
because they outnumber the low entropy ones by an astronomical (too
weak a word but I don't know of a stronger one) number. But nobody
thinks that is really true, and yet it is undeniable that you just
can not deduce a asymmetry in time from thermodynamics or from any
of the known laws of physics; this dichotomy is sometimes called
Loschmidt's Paradox or Loschmidt's Objection.
> because that is the only direction in which life can operate.
I don't see why that would be true. If the arrow of time were
reversed intelligent beings would just discover different laws of
thermodynamics. They would remember that in the distant future, that
is to say a long way from your "now", perfume molecules "were" (the
most difficult part of of reverse time thought experiments is the
grammar) evenly distributed throughout the room, and they would
remember that in the more recent future the molecules were only in
the lower right part of the room, and they would remember that in
the very recent future (very close to your "now") all the molecules
were confined inside one small perfume bottle. They would then
conclude that entropy always decreases or remains the same.
And as to how the bottle got into that room in the first place....
well, you can make educated guesses but essentially the only way to
know for sure what the past was like is to wait and see. .
But the deepest question isn't why time points in one direction
rather than the opposite direction but why it points in any
direction at all. After all the fundamental laws of physics are time
reversible, if I show you a film of non-macroscopic things you can't
tell if the film is running forward or backwards with the electrical
charges reversed and the scene photographed in a mirror. Even the
laws of logic are reversible; if I gave you line 9 of a valid proof
in pure number theory you could deduce both what line 10 must be and
what line 8 must have been.
Not in general. Proofs are non-deterministic (in the computer science
sense). You cannot reverse all classical inferences: from A & B you
can deduce B, but from B you cannot come back to A & B, as A can be
deduced from A & C too. Now in some linear logic, or in BCI
combinators algebra. But with computationalism we can say that the
symmetry at the bottom is quickly break down in the asymmetry of the
knowledgeable pov. The asymmetry is in the eyes of the duplicated
(entangled) observer, as the WM-duplication illustrates: the account
in the first person diaries break the symmetries, and record the bit
of information.
Bruno
So why do we perceive that time has a preferred direction?
If the arrow of time doesn't come from physical law it must come
from the initial conditions and we need to add a past hypothesis,
that is in the distant past for some reason entropy was much lower
than it is today.
John K Clark
--
You received this message because you are subscribed to the Google
Groups "Everything List" group.
To unsubscribe from this group and stop receiving emails from it,
send an email to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
http://iridia.ulb.ac.be/~marchal/
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
