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by rabito 2751 days ago
That is true, the time and space axis gets flipped at the event horizon. This also happens to a fast moving objects due to relativistic effects, although the roatation is usually not very high unless you go really fast. Seehttps://en.m.wikipedia.org/wiki/Minkowski_diagram

However that doesn't mean you can't move when you cross the event horizon. You can do that like usual (except for gravity pulling you inside. You can. It only means outside observer won't be able to see what you're doing, because of the time dilation (and the event horizon of course).

This kinda implies time and space are the same thing, it just depends on your point of view. Still have to see about that :D

2 comments

> the time and space axis gets flipped at the event horizon. This also happens to a fast moving objects due to relativistic effects

Neither of these things are true, and I have no idea how you are getting either of them from the Wikipedia article you linked to. Penrose-Terrell rotation, which affects how objects appear to observers when they are moving at relativistic speeds relative to those observers, does not "flip" the time or space axes; it's an optical effect due to the finite speed of light.

As I noted in another post upthread, the "flip" of time and space axes inside a black hole's horizon is a property of a particular choice of coordinates, not of spacetime itself.

> This kinda implies time and space are the same thing

No, they aren't, because there is still a fundamental difference between timelike and spacelike directions in spacetime. That is true regardless of how you choose coordinate axes.

People often mistakenly try to map space time onto an ether-like flat background, treating spacetime like a drawing where the paper is the background. It's not an uncommon kind of fumbling as someone tries to grasp these things.
To be pedantic, it's not that they are the same thing, but that they are intrinsically tied together: Time begins at the moment of first inflation.