I'm gonna start off by saying that I by no means am an expert on physics.
I'm only 14, but I'm curious about spacetime and gravity.
My current understanding is that time actually is bent in a curve relative to mass, and that we perceivee time as being straight but that it actually is bent because straight lines cant exist in a universe filled with mass.
Im pretty sure Im missing something, so to what extent is this correct?
Join the club! I'm not an expert on it either.
I believe what you may have in mind is the idea of "geodesics" in general relativity. A geodesic is the equivalent of a straight line, but in curved geometries, the original geodesic being the shortest distance between two points on the surface of a sphere, such as the Earth. The surface of a sphere is 2D but not flat (e.g. the 3 angles of a triangle do not any longer add up to 180deg, as you can check by drawing a triangle on an orange) so the geometry does not obey Euclid's rules which is what we learn at school. My understanding is that the path , called the "worldline", of something in the 4D spacetime geometry of GR follows a geodesic in that 4D geometry, and that that geometry is made to curve by mass.
So it is not that time is somehow curved but 4D spacetime is curved - by mass - and then objects follow geodesics (the equivalents of straight lines) in that curved spacetime.
Bear in mind that the worldline of even a stationary object is a line, not a point, because this is spacetime and so if it exists for a finite period of time it will follow a line in the time dimension, even though it does not move along any of the space dimensions.
Probably clear as mud, but that's the best I can do.
Perhaps someone else can add to this without confusing you......
Edited by exchemist, 05 November 2017 - 04:38 AM.