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?

Thanks

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 space**time** 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.**