To describe phenomena on the scale of atoms, we use the second great theory: quantum mechanics, which differs from general relativity in basically everything. It uses flat space-time and a completely different mathematical apparatus
It's weird to me, that the common method of attempting to describe a four dimensional thing is to immediately reduce the three dimensional thing to two dimensions...
The word "curved" is problematic for the concept of space-time because it invokes one or two dimensional thought. Space-time is a four dimensional model.
The best description of the effect of gravity on space-time on my opinion is actually a joke... Gravity sucks :)
The definition of a right angle depends on the number of dimensions. Perpendicularity and parallelism are different in higher dimensions. Space is hard.
There is no such thing as a four dimensional "spacetime". That is a abstract math only concept, nothing to do with reality. Time is not a thing, nor is it a dimension. Reality is not curved or flat. That is abstract geometry that they are talking about, not reality. Only 3 abstract dimensions are required to locate anything in reality. Time is just when you want to examine these three dimensions.
It's weird to me, that the common method of attempting to describe a four dimensional thing is to immediately reduce the three dimensional thing to two dimensions...
The word "curved" is problematic for the concept of space-time because it invokes one or two dimensional thought. Space-time is a four dimensional model.
The best description of the effect of gravity on space-time on my opinion is actually a joke... Gravity sucks :)
Curvature is well defined for manifolds with any number of dimensions. "Flat" in this context means "zero curvature", not "two dimensional".
Can I get an ELI5, please? I understand all of those words, but not the concepts behind them in this context…
The definition of a right angle depends on the number of dimensions. Perpendicularity and parallelism are different in higher dimensions. Space is hard.
https://en.wikipedia.org/wiki/Curvature#Space
https://en.wikipedia.org/wiki/Manifold
https://en.wikipedia.org/wiki/Dimension
https://en.wikipedia.org/wiki/Curvature#Flat_space
There is no such thing as a four dimensional "spacetime". That is a abstract math only concept, nothing to do with reality. Time is not a thing, nor is it a dimension. Reality is not curved or flat. That is abstract geometry that they are talking about, not reality. Only 3 abstract dimensions are required to locate anything in reality. Time is just when you want to examine these three dimensions.