hsf@hlexa.UUCP (Henry Friedman) (09/05/85)
Carrying one's memory of the present into the past would violate
causality, even if one did nothing in the past but observe.
But apart from problems of causality, time travel to past would
seem to require either:
1) "Closed loop scenario"-- anything that traveled to the past
from the future must have been back there "all along;"
or
2) Multiple worlds scenario -- any effect in past of time
travel from future was "there all along" but in one of the
many parallel universes. This would include parallel universes
in the future to contain the effects of the changes to the past.
Paul M. Koloc replied that if we spliced a change into the past
in the movie film of spacetime, there would be a problem of
whether the change would ever "replay", or just lie on the cutting
room floor.
His view of time falls into the trap of the ABSOLUTE PRESENT, the
view that there is something special about the moment we view to
be the present. This view of time also falls into the trap of
seeing the flow of time as an objective reality, instead of as
a product of conscious observation. Evidence would seem to indicate
(special relativity) that no moment in time is more special than
any other moment and that time has direction but doesn't actually
flow.
Any observer, past or future, SEES time as flowing. And if his/her
memory were of the future instead of the past, he or she would see
time flowing backward. To a hypothetical observer outside of the
spacetime continuum, spacetime would appear as a motionless
"hyperblock." However, the observer wouldn't be able to worry about
this frozen block-universe, because in order for him/her to think
(from outside of spacetime), some time of hypertime would be required!
A better analogy than Koloc's movie of time threaded through a
SINGLE projector (i.e. played only once) would be a movie film
of spacetime threaded all at once through an infinite number of
projectors.
--Henry Friedman {ihnp4,....)!hlexa!hsf