Next Tuesday is off in the future. It hasn't happened yet, and you can't say what it's going to look like. Maybe it will be like today. No big deal. But maybe you'll get hit by a falling meteor on Monday and be in the intensive care ward. Bummer. Amsterdam's Central Station, however, exists now. It's just over the Atlantic Ocean, and even as you read these words people are there, scurrying to get their trains or milling about buying weird Dutch fast food (try the greasy fried rice balls ... yum!).
So Amsterdam Central Station already exists. It's just at a different point in space. But next Tuesday, which is at a different point in time, doesn't exist.
What is up with that?
For physicists like myself, this question of the difference between space and time is rock bottom, fundamental, super important. We can't really do physics without starting with some kind of theory of space and of time and of their relationship.
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Newton's giant leap forward, 400 years ago, was to think about space and time as two totally separate domains. Space was the unchanging stage on which the drama of the world played out. Time was a river that flowed at an unchanging rate through every point on that cosmic change.
The power of Newton's conception changed the world, opening the floodgate for the mechanical era and the Industrial Revolution. There was only one small problem with this idea of a separate, absolute space and time.
It was wrong.
Of Albert Einstein's many great achievements, his most profound might be the recognition that space (the location of Amsterdam Central Station) and time (the location of next Tuesday) cannot be so easily separated. And that is why next Tuesday may already exist in the same way as Amsterdam's Central Station does.
Let me tell you about your "world line."
According to Einstein's theory of relativity, the drama of the world is "played" out not on the 3-D stage of space with time acting as an unchanging metronome. Instead, reality is composed of a four-dimensional space-time. There are three dimensions of space: left/right, forward/back, up/down. And there is one dimension of time: past/future. Just as every location on the surface of the Earth already exists in space, every event that has ever happened and ever will happen already exists in space-time.
To see how freaky this idea really gets, let's consider your life for a moment. TO READ MORE ABOUT THIS CONCEPT, CLICK HERE...
