The Physics of Time Travel

Time travel into the future has always been possible, Einstein’s equations of Special Relativity have shown us that for well over a hundred years.  We have also seen it practically here on Earth where some short-lived cosmic ray particles traveling near the speed of light actually make it down to the Earth’s surface, because they live longer than they “should” as they are traveling so fast.  This is Physics fact.  Time slows down for a fast moving object, or to put it another way, a fast moving object moves faster through time than a slow moving object.  A slow moving object says that fast moving clocks run slow – same difference.  An object moving quickly through space also moves more quickly through time compared to a slow moving object, space and time are inextricably linked together in a weird structure called space-time.  Einstein told us all this over a century ago.  This is Physics fact.  So we know that time-travel into the future is possible, we have actually seen it in practice.  What about time-travel into the past?  Suppose that time travel is possible, but just like (the increase in) entropy, it’s only possible in one direction.This would be very convenient, it removes the well-known time traveler’s paradox of traveling into the past and killing either yourself or your parents before you were born.  No such paradox occurs for time travel into the future.  Problem solved?

Time travel is possible, but just like entropy, it’s only possible in one direction.

This is also great from an information content point of view.  You can’t travel into the future and cause disruption by supplying more information than they already have.  You can’t for instance travel into the future any provide any meaningful information on Lottery numbers or Pools wins, again that’s pretty convenient – no paradoxes.

Time travel is possible, but just like entropy, it’s only possible in one direction.

In all modesty I would like this to be known as Greg’s Fundamental Law of Time Travel 🙂


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