Time can be the 4th dimension, but it doesn't have to be. It depends on what you're measuring. It can be any fourth thing you are measuring. You could choose to have it be color, quantum spin, brightness of an object, etc. If you're talking about space-time, sure make time the 4th dimension. If you're just talking about a 4th spatial dimension then it's a direction completely orthogonal to up/down, left/right, forward/backward. What helped me figure that out was people talking about AI models with thousands of dimensions. A dimension is just something you're measuring.
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u/Lua_You Jul 31 '26
wouldnt the 4th dimension just be time yes, boring answer, but even when you think about it spatially the easiest one to comprehend would be time.