Quantum Physics of Time Travel (David Deutsch & Michael Lockwood, March 1994)
Imagine, if you will, that our friend Sonia keeps a time machine in her garage. Last night she used it to visit her grandfather in 1934, when he was still courting her grandmother. Sonia convinced him of her identity by referring to family secrets that he had not yet revealed to anyone. This left him stunned, but worse was to follow. When he told his sweetheart over dinner that he had just met their future granddaughter, the lady’s response was both to doubt his sanity and to take offense at his presumption. They never married and never had the baby who would have become Sonia’s mother.
So how can Sonia be sitting here today, telling us of her adventure? If her mother was never born, how was she ever born? The real question is, when Sonia returns to 1934, can she or can she not bring her grandparents’ romance to a premature end? Either answer creates problems. If Sonia can prevent her own birth, there is a contradiction. If she cannot, that inability conflicts with common sense, for what is to prevent Sonia from behaving as she pleases? Will some strange paralysis grip her whenever she tries to enact certain intentions?
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Quantum Physics of Time Travel (David Deutsch & Michael Lockwood, SCIENTIFIC AMERICAN, March 1994)
7 pages | PDF | scanned from paper publication
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