Re: Does Man Have Free Will?

On 10 Mar 2008 13:48:27 GMT, the following appeared in
talk.origins, posted by none@xxxxxx (Eric Rowley):

From: Bob Casanova <nospam@xxxxxxxx>:

On 08 Mar 2008 10:40:13 GMT, the following appeared in
talk.origins, posted by none@xxxxxx (Eric Rowley):

<snip>

Sort of, 2) allows the future to be as mallable
as the past. He's already changed the past by sending the time
machine, which wasn't there "before", and the changed past ought
to influence the future.

...unless the entire sequence was "always" part of the
continuum. Again, this requires determinism.

And some unusual view of time, I think, where was the time machine
stored the first time through the loop, and where is the time-
machineless past on the second pass.

And wouldn't the normal view of determinism exclude time travel?
Maybe I'm confusing determinism with causuality, but we've got a
time machine popping up where/when it has no direct cause, sure ,
ultimately we can see the "seeds" of a cause but no imediate
cause.

Again, if you assume that the continuum is fixed and
"simultaneously in existence", this presents no problem, nor
does it become a problem for conservation of mass-energy.

<snip>

1) There is no macro effect from the probabilistic nature of
QM, and therefore every event is fully determined by
preceding events; this results in determinism.

And probably excludes time travel.

I don't see why; see above.

2) There *is* a macro effect from QM, and this results in a
"many worlds" scenario; all decisions go all possible ways,
and therefore it's essentially impossible to return to the
same past one left.

Past or future?

Both, actually.

There would certainly be an infinate number of pasts but
depending on the nature of time travel it might only be posible
to return to ones that were "ancestral" to ones own present?

Possibly, but that's an assumption I was unwilling to make,
especially considering how far into speculation this entire
thread has gone. Also note that if the number of pasts is
infinite, the number of futures probably enters the realm of
transfinites, since each past could spawn an infinity of
futures. (Actually, "infinite" is incorrect, since no
multiplication of finites can yield infinity. But the
numbers would get *very* large *very* quickly.)

Perhaps not though, one could almost certainly get around such a
limitation by simply going back further and changing the choices
that led to the "original" later past :-)

Uh-huh. And English *definitely* doesn't have the tenses to
discuss time travel, especially if one can change the
present by altering the past, and *especially* if one can do
so recursively.

But there's a third (at least; there may be more)
possibility: There's a macro effect from QM, but "many
worlds" is *not* correct; there's only one universe, and
while the past is fixed the future isn't (IOW, an unfolding
and solidifying decision sequence). In this scenario (unless
I'm missing something) it would be possible (actually,
"required") that one return from the "a" future to the
original past, but since the future wouldn't be fixed normal
progress through time is *not* guaranteed to arrive at the
previously-visited future. However, in this case I'm not
certain that futureward time travel would even be possible,
since how can one visit a universe which hasn't actually
come into existence yet?

Shunt the time machine onto a siding and wait for time to
catch up? ;-)
(And hope that time doesn't pass at the same rate inside the time
machine, cf Ian Watsons's "The Very Slow Time Machine")

On the other hand, how could one receive a visit from a future
that hasn't actually come into existence yet?

Point. That's why logic tends to get very confusing in this
area.

I think that time travel, in either direction, requires a rethink
of the nature of time, scraping the idea of a priviledged "now"!

Have patience; they're working on it. Maybe in another
couple of centuries... ;-)

"Now" would have to be nothing more than where you happen to be
on the timeline, no more the "real now" than your current
geographical position is the "real here".

That's the fixed continuum again, with determinism.

And this rethink would almost certainly have to involve some
version of "many worlds".

However, there was an article in Scientific American many, many
years ago that suggested that a way to avoid paradoxes would be
a variant where the branching was caused by time travel itself,
time travel involved "looping back" but not attaching to the past,
but rather continuing on a "parallel track".
So the grandfather you kill isn't the one that has to survive in
order for you to be born and invent the time machine.

That's been done several times in SF; one of the earliest I
ran across was "The Men Who Murdered Mohammed" by [quick
Google check] Alfred Bester; it was also one of the best (no
pun intended), with an unexpected kicker.

Though this might not actually require time travel as such, maybe
you could switch over to a timeline that was "out of sync" with
your original one thereby preserving the "priviledged" now, the
fixed past and the not yet existing future.

That (or something similar; alternate universes, anyway) has
*also* been done by several authors, from H. Beam Piper to
Richard Meredith to James Hogan. All different; all
enjoyable reading.

<snip>

[Re: QM]

It's obviously incompatable with his scenario.
(Unless it has some underlying reqularity.)

I believe that this (underlying regularity) contradicts the
very nature of uncertainty which is inherently
probabilistic,

Probably ;-)

But surely without a time machine we can't be _completely_
certain that this isn't some kind of psudouncertainty?
Like the psudorandom number generator in a computer, generating
what appears to be random events but if the "tape" is rewound
the same sequence would be generated every time.

Well, I'd argue that particular analogy is suspect, since
although we know that a pseudorandom sequence is generated
by a seeded algorithm we have no idea that such might be the
case for physical uncertainty.

but I'm no physicist; all I know on the
subject is from my undergrad physics courses and the little
I've read since.

(BTW, if you're interested in a fairly readable book dealing
with QM and the multiverse [and the evidence it exists] I'd
recommend _The Fabric of Reality_ by David Deutsch.)

Thanks, I'll look into it.

Enjoy!
--

Bob C.

"Evidence confirming an observation is
evidence that the observation is wrong."
- McNameless

.