How Can Empty Space Be Curved?

[Hankb]

Hello,
I just joined. I have no formal background in physics, just curiosity. So, my questions may well be simplistic to most of you. Hopefully, that is permissible, now and then! First question, if space, as it's usually defined, is empty, nothing, how can it be curved?
Hankb

 

[phinds]

Hello,
I just joined. I have no formal background in physics, just curiosity. So, my questions may well be simplistic to most of you. Hopefully, that is permissible, now and then! First question, if space, as it's usually defined, is empty, nothing, how can it be curved?
Hankb

"space is curved" is a very poor (pop-science) way of describing what happens. I agree w/ you that space is just a dimension, not something that you (or anything) can bend, but space-time has mathematical properties that make things traveling in it ACT from the point of view of Euclidean Geometry, as though they are moving in a curve. In reality they are moving in a straight line (more properly a geodesic) but they are doing so in Riemann Geometry (which is the proper geometry to use in space-time) so that we humans, who instinctively think in Euclidean terms, see them as "curved".

It was this "bending" of light rays that completely confirmed Einstein's Theory of General Relativity.

By the way, welcome to the forum.

 

[A.T.]

If space, as it's usually defined, is empty, nothing, how can it be curved?

"Curved" just means that it doesn't follow the rules of Euclidean geometry. So you could just as well ask, why empty space should follow those rules.

 

[Prof.gaming]

You could say that it is curving , just by knowing that a huge mass could make the space curve .
The most common example of the space curving is our sun , as we know that it has a huge mass , it curved the space , thus making it possible for us to so the light of the stars behind it . Even if we are seeing their light , they are not actually there ...