They say that the shortest distance between 2 points is a straight line.

It seems to me that if the Universe was 2 dimentional then that would be right, but as the Universe is either 3 or 4 dimensional, I don't see as how that can be right.

After all, don't they say that "space time" is curved? Is it curved or not?

It seems to me that if space time is curved then the shortest distance between any two points in the Universe is a curve, maybe to a person the shortest distance is or appears to be a (straight) line.

Time-space is not just what they call "outer space", time space is everywhere including here on Earth, so any two points here on Earth should also be 2 points in space-time, right?

So is the shortest distance a line or a curve? Is time-space curved or not? And is time-space also here on Earth or not?

Would the right answer be both: A line and a curve? I don't see as to how it could be: Sometimes a line and sometimes a curve, I would think that it would always be one or the other, but not both, after all the real universe in which we all are is either 3 or 4 dimentional, but not 2 dimensional, Isn't that right?

Does anybody here knows astrophysics?

Doesn't light travels in a curve or as a curve?

If a spaceship starts at point A and goes straight would it not sooner or later get again to point A where it came from? And if it does would that be because space-time is curved? And if so, would that not prove that the shortest distance between 2 points is a curve?

Any opinions on this?