warping: how??

[Mellinia]

How does mass and energy warp space and time?

[swansont]

Curved geometry is a consequence of having accelerations and knowing that the speed of light is a constant in inertial frames, and tying all of that together. If you are asking why mass and energy does all of that, the answer is going to be "we don't know," which we have recently discussed http://www.scienceforums.net/topic/52948-why-does-mass-curve-space-time/

[IM Egdall]

Here are examples of how mass/energy warps space and time.

 

Space: Imagine two points in outer space where there is no gravity. From your point of view here, they are one above the other (vertical). You measure a certain distance between these two points. Now assume you place the Earth just below these two points. Now there is a gravitational field where these two points are. Someone far away where there is no gravity will measure those same two points as being a longer distance from each other! This is due to the stretching (or warping) of space due to the mass/energy of the Earth.

 

Time: Place your watch over your head. Now put it on the ground. Your watch actually runs a tiny bit slower on the ground than over your head. Why? The mass/energy of the Earth slows down (warps) time. The closer to the Earth, the stronger the gravitaional field; thus the more time slows down.

 

Space and time warping effects are very small here because Earth has a relatively small amount of mass/energy. However, this warping of space and time due to Earth's mass/energy is what makes objects fall to the ground and man-made satelites and the Moon orbit the Earth. Space and time warp (or spacetime curvature as it is called) is gravity.

Edited February 13, 2011 by I ME

[Mellinia]

Yeah, i'm trying to ask why...because a book I read told me that and it didn't explain why. Would the following perception be correct? An empty space and time field is before you. To maintain the speed of light as a constant, the field stays in tension. When you introduces a significantly large piece of mass/energy, the field is affect. The speed of light is still relative to space and time, and space warps to balance the shift and transfers more motion through space into motion through time.

[ajb]

An empty space and time field is before you.

 

Time field? Do you mean an empty space-time?

 

To maintain the speed of light as a constant, the field stays in tension.

 

I don't understand.

 

When you introduces a significantly large piece of mass/energy, the field is affect. The speed of light is still relative to space and time, and space warps to balance the shift and transfers more motion through space into motion through time.

 

In short, space-time is curvature is a consequence of the equivalence principle. As swansont has said, this has been discussed recently in another thread.

[Oldman]

Thanks to Millinia for asking this question. I read the answers above; they do not even come close to answering this question.

 

We physicists do not know how matter warps space, time, or spacetime! Some modern cosmologists have proposed that matter creates space (and maybe time)!

 

This question was first asked by the great astrophysicist E. A. Milne in his book, Relaivity Gravitation and World-Structure, in 1935. When I was a graduate student in the late sixties, I read this book on my own against my General Relativity professor's advice.