If I had to guess, what you’re referring to is how higher dimensions are “orthogonal” (at right angles) to the dimensions below it.
How can you arrange 3 sticks orthogonally using 2 dimensions of space?
The same idea can be applied to arranging 4 sticks orthogonally using 3 dimensions of space.
Maybe to a flatlander, a theoretical being that only experiences 2D space, they’d have a different word for the third dimension like we have a different word for the fourth. That wouldn’t mean the third dimension isn’t spatial.
Soo what are you wondering? I’d expect it’s obvious in our everyday experience that time is a bit different from space.
If you want a something more mathematical, pick an equation from physics. It probably treats time separately from space. The only kind-of exception I can think of is general relativity, and even it ends up producing metrics that give time the opposite sign, like the flat space example the other poster mentioned.
The directionality of time is a bit more subtle and emergent. But, you don’t need it to look at a double light cone, which just follows from Maxwell’s equations or the other wave equations in nature, and observe that while a constant-time slice of it is a sphere, the whole thing is not a hypersphere.
If somebody here knows their way around QFT they might have something to add, but for all the rest of science it’s just kind of built in.
If I had to guess, what you’re referring to is how higher dimensions are “orthogonal” (at right angles) to the dimensions below it.
How can you arrange 3 sticks orthogonally using 2 dimensions of space?
The same idea can be applied to arranging 4 sticks orthogonally using 3 dimensions of space.
Maybe to a flatlander, a theoretical being that only experiences 2D space, they’d have a different word for the third dimension like we have a different word for the fourth. That wouldn’t mean the third dimension isn’t spatial.
Soo what are you wondering? I’d expect it’s obvious in our everyday experience that time is a bit different from space.
If you want a something more mathematical, pick an equation from physics. It probably treats time separately from space. The only kind-of exception I can think of is general relativity, and even it ends up producing metrics that give time the opposite sign, like the flat space example the other poster mentioned.
The directionality of time is a bit more subtle and emergent. But, you don’t need it to look at a double light cone, which just follows from Maxwell’s equations or the other wave equations in nature, and observe that while a constant-time slice of it is a sphere, the whole thing is not a hypersphere.
If somebody here knows their way around QFT they might have something to add, but for all the rest of science it’s just kind of built in.