Exploring Einstein's General Relativity: The Effects of Gravity

[Arlene G.]

According to Einstein's General relativity, gravity is known as a curvature of space-time fabric. I watched a video clip on youtube and it said that gravity is not really a force but a shape of space and time. Then here comes a question-if gravity is not a force and just a curvature of fabric of space-time, then how does it affect the objects in Earth not to float but to pull them downwards?

Second of all, how can gravity hold all sorts of celestial bodies in place without letting them move away from their orbits if it is not the force? In a 3D version of space time fabric-not considering time here-, i can imagine space time fabric curving around each bodies. The curvatures(gravity) just seem to 'bend', and not 'hold' the planets, stars, etc...?

Am I getting something wrong?
Please help meX)!

 

[haushofer]

According to Einstein's General relativity, gravity is known as a curvature of space-time fabric. I watched a video clip on youtube and it said that gravity is not really a force but a shape of space and time. Then here comes a question-if gravity is not a force and just a curvature of fabric of space-time, then how does it affect the objects in Earth not to float but to pull them downwards?

Because objects in spacetime following so-called geodesics. A geodesic on a plane is a straight line, but on a sphere it is curved (e.g. the line from the North pole to the equator and then to the south pole as a half circle). This is what we call "gravity", but objects merely follow geodesics.

Second of all, how can gravity hold all sorts of celestial bodies in place without letting them move away from their orbits if it is not the force? In a 3D version of space time fabric-not considering time here-, i can imagine space time fabric curving around each bodies. The curvatures(gravity) just seem to 'bend', and not 'hold' the planets, stars, etc...?

Am I getting something wrong?
Please help meX)!

Again: it's the "fact" that objects seem to follow geodesics in spacetime. The orbit of a planet is a geodesic in the spacetime, of which the geometry is (mainly!) determined by the Sun.

 

[Arlene G.]

Haushofer, danke sehr!
Now I quite understand the point that I firstly mentioned:)

I now remembered the answer to my second question.
It was on tip of my tongue and you helped me out. XD