One of the greatest challenges of modern physics is to find a coherent method for describing phenomena, on the cosmic and microscale. For over a hundred years, to describe reality on a cosmic scale we have been using general relativity theory, which has successfully undergone repeated attempts at falsification.
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