X-Message-Number: 921
Subject: CRYONICS - Time Travel
From:  (Edgar W. Swank)
Date: Mon, 22 Jun 92 11:59:07 PDT

In his comment in message #880  (Micro/macro brain damage), Steven
Harris expresses his incredulity about "universal technological
resurrection" and rescue via time-travel.
I share his skepticism about universal tech resurrection, or the
"Omega Point" as described by Barrow & Tipler in THE ANTHROPIC
However, Time-Travel is still a theoretical open topic.
Proposed mechanisms include using Kaon, Anti-Kaon pairs to communicate
information backwards in time (See Analog Sept. 88); Wormholes in
Space-Time (Analog June 89); Massive rotating cylinders and black
There is a large bibliography concerning time travel and FTL travel in
"Great Mambo Chicken & the Transhuman Condition by Ed Regis.
Finally, in response to an inquiry, Frank Tipler (himself!)  wrote to
me(!)  in February:
"Thank you for your letter of 29 January. I'm afraid that I have no
more reprints of my article "Rotating Cylinders and Global Causality
Violation," but you should be able to find it in any research library.
It appeared in Physical Review D9, 2203-2206 (1974).  My other papers
on Time Travel were "Causality Violation in Asymptotically Flat
Spacetimes", Physical Review Letters, 37, 879-882 (1976); "Causally
Symmetric Spacetimes", Journal of Mathematical Physics, 18, 1568-1573
(1977); "Singularities and Causality Violation", Annals of Physics,
108 , 1-36 (1977); and "Existence of Closed Timelike Geodesics in
Lorentz Spaces", Proceedings of the American Mathematical society, 76,
145-147 (1979).
"The most recent work on Time Travel is being done by Kip Thorne and
his associates. His most detailed paper is Friedman et al, Physical
Review D 42, 15 September 1990, 1915. See also Frolov and Novikov
(Physical Review D 42, 15 August 1990, 1057).
"Steven Hawking is hostile to the whole notion of time travel, and is
basically making the same argument as Larry Niven in his story. Write
Hawking for a copy of his latest preprint on this subject, which is
entitled "The Chronology Protection Conjecture." (His address is:
Professor S. W. Hawking, FRS, Department of Applied Mathematics and
Theoretical Physics, Silver Street, Cambridge, ENGLAND.)
"In regard to Price's comment, there is (to my knowledge) no error in
my rotating cylinders paper. However, that paper was concerned with a
time machine that had existed forever, and hence did not address the
question of whether time machines could be built. I addressed these
questions in the other papers referenced above. What I showed in these
papers was that the formation of a time machine necessarily created
singularities (more precisely incomplete null geodesics) at the
instant of formation -- provided the Weak Energy Condition held. In a
still later paper ("Energy Conditions and Spacetime Singularities",
Physical Review, D17, 2521-2528 (1978), I showed that the Weak Energy
Condition could be relaxed to the Averaged Weak Energy Condition. I
regarded these theorems as ruling out time machine formation, and
moved on to other projects.
"But in the period 1987-90 Thorne and Company argued that the Averaged
Weak Energy Condition was not necessarily true. Unfortunately, in 1991
Professor Robert Wald of the University of Chicago showed that the
postulates of quantum field theory require the validity of the
Averaged Weak Energy Condition, whereupon Amos Ari of Cal Tech
published a paper in Physical Review Letters arguing that the
singularities required by my theorems need not be curvature
invariants, and hence need not prevent the construction of time
So I would consider it a valid option to specify that one's cryonic
suspension funds be used to establish a trust for time travel research
in the event no physical remains could be found to freeze.

 (Edgar W. Swank)
SPECTROX SYSTEMS +1.408.252.1005  Silicon Valley, Ca

[ Edgar, cryonic suspension is, subjectively, a form of time travel to the
  future.  The proposal for time travel (to the past), however, reminds
  (message #0013). :-) - KQB ]

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