Recipe for dragon stew: First, find a dragon . . .
Matt Visser, Lorentzian Wormholes
Having come this far, you are finally in a position to appreciate
the physics that needs to be in place if we are to construct a time
machine. I have discussed Einstein’stwotheories of relativity, both
the special theory in which time and space are united into fourdimensional
spacetime, and his general theory in which spacetime
is warped and twisted in the presence of matter and energy. Both
theories are going to be needed in this chapter. I have discussed
the nature of time and looked at the sort of problems that we must
overcome if we insist on the possibility of time travel into the past.
Now it’s pay-off time.
I will put on hold all the (quite valid) objections to time travel
for the time being and adopt the pragmatic, and highly optimistic,
view that as long as time travel is not forbidden by the laws of
physics as we understand them today then there is hope. I will
show how we might go about building the simplest possible time
machine. Don’t take this to mean that I have climbed down off
the fence in favour of time travel, but rather that I am leaning
dangerously over to one side (for now).
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