Let’s be honest, time travel fascinates us all, no matter how much physics we know. There is something mystical to me about how elusive the answer to whether it’s possible is.

There are many theories of time travel, those admitting the possibility of the Grandfather Paradox and those that preclude it; those that attempt to explain why nobody from the future visited us yet; those that involve Nature as some kind of intelligent designer that scrambles to avoid paradoxes (I’m looking at you, J. J. Abrams); those that constrain time travel to a subset of circumstances (my favorite is the theory of time travel put forth in Primer).

I considered the other day what consequences unrestrained travel back in time would have. I can’t just appear without causing any side effects on the time-space that I traveled to: the mass/energy of the universe wouldn’t be conserved (so I could build a kind of automated time travel machine that continuously adds energy or mass to the universe, or–even better–reduce the entropy of the entire universe). So my arrival needs to be coupled with disappearance of energy or mass. Where would that energy disappear to?

This entry was posted on Wednesday, March 24th, 2010 at 12:07 and is filed under for reflection, technology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.