How can we visualize 4D spacetime and how gravity plays a role in 4D spacetime??
This is a FAQ; did you try searching for previous PF threads? This very question was discussed as recently as a few days ago.
If you take and combine two of the spatial dimensions say z and y then have time be your third dimension on a graph it is pretty easy. Its used in a lot of examples and what not in books.
We can't visualise it we don't visualise in 4D. But here are models to help us understand.
General realtivity/special relativity etc.
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