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unclebobmartin /
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2024-08-13 18:47:17

unclebobmartin on Nostr: If the idea of curved space time, as described by General Relativity (GR), confuses ...

If the idea of curved space time, as described by General Relativity (GR), confuses you, consider the following analogy.

The theory of GR was sparked by Einstein’s “happiest thought”, that gravity and acceleration are equivalent.

That means that you, standing on the ground, are accelerating upwards. But you can detect no motion in that direction. How does that make sense?

Consider the amusement park ride sometimes known as “The Rotor”. It is a room sized cylinder that you walk into and stand against the back wall. Then the cylinder is spun up and you are pressed against the wall by centrifugal force. For you, gravity seems to shift and you feel as though you are lying on your back with the center of the cylinder above you.

Your acceleration vector is toward the center of the cylinder. But your velocity vector is parallel to the back wall, 90 degrees away from the acceleration vector.

So, when you are standing on the ground, accelerating upwards, your velocity vector, as you move through curved space time, is shifted 90 degrees into the dimension of that curvature, which is a dimension you cannot directly perceive.
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