As a professor emeritus of physics at the University at Buffalo, I'd like to respond to the March 15 article on discussions of physical wormholes and time travel by Kip Thorne. Readers should be wary of the difference between real science and science fiction. Real science must entail logical consistency as well as empirical verification. Science fiction needn't entail either.
Thorne thinks Einstein's theory of general relativity implies these features of matter in real science, but he is certainly wrong. The wormhole idea goes back to the 1930s, when Einstein and Nathan Rosen were investigating a generalization of the spacetime language with which the solutions of relativity theory were to be expressed. But this was not more than a geometric generalization of the expression of the theory. It was not meant to be a carving of tunnels in a physical space and time, connecting different universes, into which human beings may travel.
Human transportation in space and time would be a sequence of physical experiences. In contrast, the wormhole is a geometrical imposition on the language of the topology of spacetime. The wormhole idea may be entertaining, but it is not real science.
Spacetime in Einstein's theory is not a physical existent in itself. It is a language that is meant to express meaningful ideas. A translation from English to Japanese, for example, does not alter the meaning that is being expressed. The wormhole in Einstein's general relativity theory is not more than an attempt to create a more useful spacetime language that we choose to express the physical laws.
To demonstrate the error in Thorne's interpretation, look at the example he used -- time travel. There is no such implication in relativity theory because the "time" parameter is not a physical sequence of experiences. It is only a measure that expresses the laws of matter.
Going to Thorne's own example, a doctor could travel back in time to meet his father before his father had met his mother. He could then operate on his father to make him sterile. Thus, the doctor could never have been born -- he does not exit. But he does exist.
To get out of this logical paradox by saying "I'd give heavy odds that explosions destroy all time machines," Thorne is insulting readers' intelligence.
MENDEL SACHS Williamsville