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Time-Travel. The Causal Paradox. Somewhere in Time. Back to the Future. A causal loop is a series of events (A, B, … Z) such that: A causes B which causes… Z which causes A. The Universality of Causation : Everything has a cause . The Causal Paradox.
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Time-Travel The Causal Paradox
Back to the Future • A causal loop is a series of events (A, B, … Z) such that: A causes B which causes… Z which causes A. • The Universality of Causation: Everything has a cause.
The Causal Paradox • If time travel were possible, causal loops would be possible. • If causal loops were possible, it would be possible to have self-caused and uncaused things. • It’s not possible to have self-caused or uncaused things. • [So] Time travel isn’t possible.
The Altered Past Paradox • If time travel were possible, it would be possible to change the past. • It’s not possible to change the past. • [So] Time travel isn’t possible.