Time Travel

"Jonathan Silverlight"
wrote in message ...
In message .net,
Paul
Lawler writes
"Lloyd Jones" wrote in message
...
Just wondering what people think about it.

Into the future, yes.

Into the past, no.

There's an article at

http://www.daviddarling.info/encyclopedia/C/closed_timelike_path.html
with some very interesting internal links.
I'd never heard of a Gott Loop or a van Stokum Cylinder, though it's
actually the device in Larry Niven's "Rotating Cylinders and the
Possibility of Global Causality Violation" and Poul Anderson's "The
Avatar". "Rotating Cylinders..." is a paper by Frank Tipler, so the
question might be "does he cite van Stokum ?" (who published in 1937)

The point of all this is that people found very early that relativity
does allow travel into the past.

I feel obligated to point out the Larry Niven and Poul Anderson are
science "fiction" writers. I don't think you can successfully posit time
travel into the past without a wormhole, which to my knowledge has never
been observed or created. As far as we "know" (hypotheticals aside) one
can travel into the future, but not into the past.

In message et, Paul
Lawler writes
"Jonathan Silverlight"
wrote in message ...
In message .net,
Paul
Lawler writes
"Lloyd Jones" wrote in message
...
Just wondering what people think about it.

Into the future, yes.

Into the past, no.

There's an article at

http://www.daviddarling.info/encyclopedia/C/closed_timelike_path.html
with some very interesting internal links.
I'd never heard of a Gott Loop or a van Stokum Cylinder, though it's
actually the device in Larry Niven's "Rotating Cylinders and the
Possibility of Global Causality Violation" and Poul Anderson's "The
Avatar". "Rotating Cylinders..." is a paper by Frank Tipler, so the
question might be "does he cite van Stokum ?" (who published in 1937)

The point of all this is that people found very early that relativity
does allow travel into the past.

I feel obligated to point out the Larry Niven and Poul Anderson are
science "fiction" writers. I don't think you can successfully posit time
travel into the past without a wormhole, which to my knowledge has never
been observed or created. As far as we "know" (hypotheticals aside) one
can travel into the future, but not into the past.



The point of my post was that the mathematics say otherwise. Niven and
Anderson assume that you can achieve time travel with a cylinder which
isn't just finite but fairly small (the original papers posit infinite
length) but some of the other papers describe finite devices. Huge ones,
with masses from Jupiter up to a galaxy, but finite.
Tachyons are another possible example, and AFAIK it's still possible
that the neutrino is a tachyon.
Time travel has been the subject of serious theoretical study for about
80 years, and no-one's yet worked out a solution to the problems of
causality it produces. And unless he's been wildly misquoted, Ronald
Mallett is planning a practical demonstration.
Oddly enough, I gather that Stephen Hawking's latest ideas rule out the
wormhole effect. But as we haven't even reached the centenary of the
first theories I'm not worried.

All of your replies is interesting.

I think that in the future ( most probably in many thousands of years, if
not longer) If we humans are still around, we will some how find a way to
time travel. If anyone says it's impossible they are either naive or narrow
minded.

If we do find a way of doing it, the world in my opinion would be 1000x
times more dangerous than it is now.

LJ

Lloyd Jones wrote:

All of your replies is interesting.

I think that in the future ( most probably in many thousands of years, if
not longer) If we humans are still around, we will some how find a way to
time travel. If anyone says it's impossible they are either naive or
narrow minded.

If we do find a way of doing it, the world in my opinion would be 1000x
times more dangerous than it is now.

LJ
So if someone disagrees with you "they are either naive or narrow minded."?
Hmmm, just because you want time travel to be so (beyond our normal
continuous moving into the future), doesn't mean it must be.
Eric

"Lloyd Jones" wrote in message
...
All of your replies is interesting.

I think that in the future ( most probably in many thousands of years,
if
not longer) If we humans are still around, we will some how find a way
to
time travel. If anyone says it's impossible they are either naive or
narrow
minded.

Wilth lack of evidence to the contrary we could just as easily state
that if anyone says it's possible they are either naive or narrow
minded.

If we do find a way of doing it, the world in my opinion would be
1000x
times more dangerous than it is now.

Not to mention the obvious paradox. Suppose you go back in time and kill
your father before you are born. Then you would never be born, but if
you had never been born you would not be there to go back in time to
kill your father. See the problem?

"Jonathan Silverlight" wrote
in message ...

There's an article at
http://www.daviddarling.info/encyclopedia/C/closed_timelike_path.html
with some very interesting internal links.
I'd never heard of a Gott Loop or a van Stokum Cylinder, though it's
actually the device in Larry Niven's "Rotating Cylinders and the
Possibility of Global Causality Violation" and Poul Anderson's "The
Avatar". "Rotating Cylinders..." is a paper by Frank Tipler, so the
question might be "does he cite van Stokum ?" (who published in 1937)

The point of all this is that people found very early that relativity
does allow travel into the past.

I love when people start arguing that time travel is possible they point to
some scientific paper that postulates a necessary constructed cylinder with
a mass of most of the universe or whatever.

Um...ok. Tell you what, I'll go to Home Depot and get some 2x4's and 4x8
sheets of plywood and start construction on that immediately.

(Several billion years later).

Damn. On paper, I would have sworn this thing would work..... Someone
forgot to carry the 2...

"Lloyd Jones" wrote in message ...
Just wondering what people think about it.

I knew you were going to say that.

I knew you were going to say that.

Give you a clap.

LJ

Half of the greatest scientist in the world are debating whether it's
possible or not, you can't say it's defiantly not or ever possible.

LJ

"Lloyd Jones" wrote in message
...
Half of the greatest scientist in the world are debating whether it's
possible or not, you can't say it's defiantly not or ever possible.

Sure I can... unless you can prove me wrong. g