can someone give me an explanation of space-time that isn't a novel or so long?

Question

i got the dictionary definition, "The four-dimensional continuum of one temporal and three spatial coordinates in which any event or physical object is located.", which i understand, but i was thinking about somethin i saw on Nova, i think, that explained gravitational pull through this analogy; imagine that the sun is a bowling ball on a trampoline, and the earth is a golf ball, the sun creates a depression in space-time that draws the earth toward it.

Answer 1

The bowling ball analogy is oft used and very misleading - I think it makes things harder not easier to understand, because it is so wrong.

Until the early 20th century space and time were treated separately in science. With the advent of special and general relativity it became clear that the two were intimately linked, and it became more sensible to treat the two in a single, consistent geometrical manner as space-time.

To do this it is usual to choose units in which the speed of light is 1 and is dimensionless. You then measure both time and distance in seconds.

You can then describe space-time by a tensor (a kind of matrix) which tells you how to get from real physical objects to measurements of them. In flat space, the metric is diagonal and just has elements 1,1,1 for spatial dimensions and -1 for time. What this tells you is that to get the interval (distance) between two events you simply take
s^2 = x^2 + y^2 + z^2 - c^2t^2.

Now when space curves, these values are NOT zero and they change with position. This means that the interval you get above depends on WHERE you are - its as though the length of your ruler changes as you move through space. This is what is meant by curved space time.

Answer 2

In 25 words or less...

Space bends under extreme gravity pull, bent space is the depressed rubber sheet. Mass causes that gravity pull, where mass is the golf ball.

Answer 3

It was a dark and stormy night. Space seemed to stretch on forever in all directions - left, right, forward, backward, up, and down. Time seems to crawl toward infinity. The updraft was incredible. I began to regret skipping that last lesson in packing my parachute correctly.

Answer 4

both are only tools of earth. time is not really linear & space is not empty.