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 COSMOLOGICAL PRINCIPLE. 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 holes. 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 machines." 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 one of option (5) in "JOJO's BODACEOUS SELF-PRESERVATION CLINIQUE" (message #0013). :-) - KQB ] Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=921