Lirdon t1_j3m36rb wrote
Spacetime is a concept on which space and time are connected as an intrinsic property. Especially when considering that you have an absolute constant, which is the speed of light, you can always convert one to the other. We measure distances in light years for that reason. But it goes deeper.
You can bend space, weird huh… not in the same manner that one might consider bending of a rod, but the general analogy which, though not perfect, works for many people, is putting a ball in the middle of a taught sheet of cloth. The sheet will sag in a certain way towards it, bending it. The thing is if you bend space you also bend time, in extremes, such as the proximity of black holes, time dilates, and to an outside observer looking at you it looks like you’re in slow motion.
Bigjoemonger t1_j3njf5g wrote
The ball in a sheet cloth is a nice two dimensional model.
But I like this example as a three dimensional model.
Imagine a 3 dimensional grid of bungie cords so you have bungie cords going up and down, left and right, towards you and away, such that the bungie cords are connected at equal segments and the space between the bungie cords forms a cube.
Now grab several bungie cords close to each other and pull them close and tie them together. The bungie segments closest to those segments get warped and stretched out of position while bungie segments further away are relatively unaffected.
In space the spots where the bungies are tied together represent massive objects like stars and planets. And the amount of warping/stretching represents the gravity well around that object.
Zxruv t1_j3nktic wrote
When conceptualizing spacetime does the sheet only represent a "slice" of spacetime in the analog? If so, could you take the same concept and represent it as a weighted sphere embedded in a large sponge, with the sphere causing the sponge to sag? The sponge would sag more in the immediate area of the sphere and less so as you move away from the sphere?
keeperkairos t1_j3nodqw wrote
Basically. There is no up down left or right in space, the massive object is warping in 3 dimensions, not just a 2D sheet.
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