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What do we really mean by "near" and "far"?
In a way, distance is just a measure of how hard it is to get between two points.
The harder to get from here to there, the more distant "there" is.
Thinking about distance in multiple dimensions is easy now!
In two spatial dimensions, a point a mile north and a mile east is more distant than
one that's just a mile east - it's harder to get to.
What about one space and one time dimension?
Easy as well!
Getting to a point a mile east in 10 minutes is a lot harder than getting there in 10 hours
- so one mile east and 10 minutes in the future
is way more distant than 1 mile east and a day in the future.
And a point that's a mile east right now is impossible to get to - so it's super distant!
But hold on - that would mean that 10 minutes is farther away than 10 hours!
Doesn't that seem backwards?
It kind of is - but it's the way the universe works:
in special relativity, more time equals less distance!
So distance in time is negative!
And if you travel east and into the future in such a way that the negative time & positive
space distances cancel out, your total distance will be zero.
And you'll be traveling at the speed of light!
So how far away is tomorrow?
It's closer than you think.