Time travel and the 2nd law of thermodynamics

  • Thread starter jewfro420
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  • #1
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it is often stated that time travel is not forbidden by any law of physics.

but doesn’t the second law of thermodynamics forbid it because going back in time would involve a decrease in entropy?
 

Answers and Replies

  • #2
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I think the only way around violating the second law goes something like this:

Suppose someone travels back in time from say the year 2000 to 1990. Does this increase entropy? No because you always existed in 1990 and the entropy of the universe reflects this. Its not like you did not exist in the first version of 1990 but existed in the later ones.
 
  • #3
I like Serena
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Suppose you go back into a parallel universe that looks exactly like the universe of 10 years ago.
And suppose you bring a lot of entropy back with you, making sure the entropy of this parallel past is greater than the entropy in the now.

I think that would preserve the law...
 

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