When using imaginary numbers to calculate time, the distinction between space and time disappears. Why is this, or rather, how is this?
by 
RBarag
ANSWERS: 1
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Put it rather the other way round: the imaginary number representation was invented to provide a way of representing spacetime as it appears to be as a single mathematical quantity rather than two independent ones. Maths is an abstract tool: physicists pick the maths that seems best to model the real world. They wanted a concept of "distance" son spacetime. Distance in space is, by Pythagoras, sqrt(x^2 + y^2 +z^2). It is a useful model to view things in space time as flying *apart* at the speed of light. Which means that the distance in 4-space is sqrt(x^2 + y^2 + z^2 - (ct)^2). And it is that minus sign which brings in the imaginary numbers. Which is a bit frightening. But physicists persist, and find that it seems to give answers that are compatible with the real world as we see it. In particular, anything which the imaginary numbers do not cancel out is something which simply can not happen (e.g. time travel, FTL travel). And that seems to be the way the universe is.
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