[net.physics] Back to the Past

jimc@haddock.UUCP (08/30/85)

Here is a question from one who knows next to nothing about physics.
Seeing how there has been extensive talk in other newsgroups (like
net.movies) about the conceptual paradoxes in traveling backward
through time, I am now curious:  is travel into the past theoretically
possible?  Or is this subject relatively untouched by physics?

I have heard of the idea of some elementary particles going back
through time in certain situations which have yet to be effected,
but I don't know how reliable such speculation is.  Can anyone
comment on this?

I also know that Einstein's special theories picture time as
relative, and that time passes more slowly for objects in motion
than for objects at rest.  However, this would seem to permit
only travel into the future at varying rates, without any
accommodation for travel into the past.  Did Einstein ever
discuss time travel in the opposite direction?

	
				Jim Campbell

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"No dance tonight!"

pmk@prometheus.UUCP (Paul M Koloc) (09/02/85)

Jim Campbell ima!haddock!jimc wants to know. 
> . .. .is travel into the past theoretically possible?  Or is this 
> subject relatively untouched by physics?
> I also know that Einstein's special theories picture time as
> relative, and that time passes more slowly for objects in motion
> than for objects at rest.  However, this would seem to permit
> only travel into the future .. . . 

Time travel and "space" travel can be compared through analogy.   

One way to travel in space is to just "walk out of the room" or change
location continuously with respect to the local neighborhood (inertial 
frame)- WORD. Another way to move from location to another would be to
"vanish" from inside the room and "re-appear" outside the room.  This
a favorite modes of "sci fi" travel: (The Greatest American Hero, Star
Trek, etc.). The "jump" is the kind of thing that electrons do when 
they transfer orbits in atoms. It's hokey in real physics because there 
has to be a connection between the locations.  If its connector is a 
"beam" as in "Startrek" then it would appear that other matter existing
along the beam path would interfere.  Of course, transforming to 
"neutrinos" would solve the transmission problem and beams could reach
otherwise incredible locations such as engineered cave complexes deep
within a planet's interior. The big problem becomes how to physically
stop and then re-transform the neutrino beam's information (there's
one of those WORDS again) into useful living beings. 

There is another mechanism to drive the "vanish point" - "re-appear point"
space travel, and that has to do with first going into a non-three-space
dimension. Then slide sideways to the projection point (co-ordinates) 
of the three space "re-appear point" and then pop back into three space!
Coming out with an air displacement "wind or bang" as a kind of micro
"trs80 (:->) " CONTROLLED "big bang".  Then you saw me not , but now you do. 
This dimensional detour technique gets you around the granite, planetary
iron cores and space dust more or less unscathed. 

In time travel (jump type), it has "physical" problems.  What one has to 
do is to "cut out" of the movie at one location and then go to the earlier 
or latter part of the film and "cut and paste" oneself back in.  But going 
to the past, will that really "play" again?, or will you simply end up on 
the "cut room floor", or perhaps have to wait for another "super 
intelligence" to check our movie out for another "replay". Travel to the 
future may not have that problem but can we "get back" without a replay?

Then there is the effect of effectively disrupting the conservation of 
energy, charge,  . (information) laws.  After all, matter "just vanished!"
OR: "he just appeared, right over thar! from nathin!".  There will be strong 
"creation annihilation" effects generated by a "fast" vanish/re-appear 
event.  Both will generate powerful EMP's or transient electrical effects.

As matter appears "instantaneously" (or disappears), it looks in that
instant as an object of pure positive (negative) charge) for ~ 10~(-24) 
seconds.  Cosmic rays also have frequencies on the inverse order of 
magnitude.  The instantaneous field strength is enough to set up 
electric oscillations whose resonances depend on physical size. There 
are objects in space that appear to have given off enormous EMP's that 
have electrically polarized matter for light years beyond their 
boundaries. This may be a related effect.  

Finally "time walking" appears to be the safest route (one way) to 
the future. That will take time but for example, one could conceivably  
get to the year 2010, by only aging a few perhaps five years. This 
can be done by parking at a stagnation point between "twin neutron stars"
and taking advantage of the super slow clock speed.  Then in five years
or so do a quick vanish point re-appear point space "jump" back to
the year 2030 on earth!.   

The past, however, isn't as inaccessible as the future when one considers
the vast amounts of knowledge "frozen in" to the rocks, cosmos and memories
or works of man. 

        "Scotty what's the frozen chicken doing in the transporter room?"

	"Well Captain, the marooned crew is beaming up, and I figured 
            they would be half starved, and it'll be ready faster and
            fresher than Kentucky fried!"

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