On Fri, Jan 10, 2014 at 9:06 PM, meekerdb <meeke...@verizon.net> wrote:

> I'm not sure what "time is symmetrical" means to you.

The term is self evident.

> It's the equations of dynamical evolution that are t-symmetric in physics

Yes, time symmetrical laws of physics would usually mean that time was
symmetrical too, but not under very unusual initial conditions, like a
state of very low entropy.

>> then retro-causality exists, so how can realism hold? How can the
> outcome of a coin flip today have a definite value independent of the
> observer if next year or next millennium someone can cause a change in
> today's coin flip?

 > If the coin flip today had a definite outcome

Then things would be realistic.

why do suppose some one the future could simply choose it to be a different
> outcome?

Because if time were symmetrical then retro-causality would be just as
common as forward-causality and things would not be realistic.

> "free will"?

Cannot comment, don't know what ASCII sequence "free will" means.

> So you think realism would have no meaning in Laplace's deterministic
> universe?

Not at all, if things were deterministic then their values would exist
regardless of if somebody was observing them, or even if he could.

>> And by the way, if time is symmetrical then there is no point in ever
>> actually performing an experiment because you would remember the future as
>> clearly as you remember the past, so you would already remember the outcome
>> of the experiment just as clearly as you remember setting up the
>> experimental apparatus.
> > Not if "time is symmetrical"

No,*only* if time is symmetrical.

 > "dynamical equations are t-symmetric" and memory depends on the state of
> a lot of particles in your brain so that the 2nd law applies.

If the 2nd law applies then time is not symmetrical because it says that
something (entropy) gets larger in one direction than it does in the other,
and that is lopsided.

 John K Clark

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