How does gravity curve space-time?

Question

How does gravity curve space-time?

Answer 1

It is mass which curves spacetime, and that curvature is perceived by us as gravitational attraction. The greater the concentration of mass; the more spacetime is curved. If we knew how, we would be as gods.

Answer 2

It does not.  Gravity is what we see as the result of the curvature of space-time by objects with mass.  It is the effect, not the cause.

Answer 3

This is too advanced for me. Look out on Wikipedia

Answer 4

in the presence of a very strong gravitational field, light is affected. a superstrong gravitational force may also attract light, causing light to travel slower.(we must know that time and light has a very intimate relationship - the speed of light is directly proportional to the rate time passes by). if the light travels slower, the speed threshold decreases (the normal speed threshold is 3 X 10^8 m/s), hence making the time run slow, and curving spacetime

Answer 5

I never really liked the rubber sheet analogy, since in order for a ball to "fall" into a warped dimple on a sheet, there must be gravity to pull it down. So they are using gravity to explain gravity, and that leaves me a little cold.

I like Einstein's analogy that he used to explain the Equivalence Principle. He used a man in an elevator, I will use an astronaut and a rocket.

Picture an astronaut in free fall above the earth. He is accelerating toward the earth's center, but he feels no forces acting on him. There is no reaction force against his suit, he does not feel his arms or legs being pulled or being thrown back, he simply floats freely as he accelerates at 9.8 m/sec^2. Now that's unusual - why doesn't he feel a force if he is accelerating faster than most cars accelerate?

Now imagine a manned rocket with no windows and no instruments. The astronaut stands on the floor of the rocket, and the rocket is sitting still on the surface of the earth. The pilot feels the force due to 1G acting against the soles of his feet. Now he feels a force, but he is not accelerating. How can that be?

Now imagine that same rocket hovering in the air 10 feet above the ground. The engines are firing like crazy to keep the rocket in one place, but the astronaut still feels 1G against his feet. With no instruments and no windows, he cannot tell whether he is on the ground or hovering in mid air.

Finally, imagine the rocket in outer space, far from any gravitational source. If the engines are started, the rocket can be set to accelerate at 1G. If that occurs, then the astronaut can again stand on the floor and not know whether he is on the ground, hovering in mid air, or accelerating in outer space.

What Einstein said, in his normal brilliant understated fashion, is that the astronaut cannot tell the difference between these cases because THERE IS NO DIFFERENCE. We think that acceleration requires a force to initiate it - certainly that is true in Newtonian physics. But Einstein realized that it is not true in a gravitational field. The gravitation warps spacetime in a manner that causes motion to occur with no forces acting on the moving body. This is what is meant by the curvature of spacetime. So you will accelerate toward the earth's center until some force acts to stop you - like the surface of the earth pushing against your feet or the floor of the spacecraft holding you ten feet above the ground. In a gravitational field, spacetime curvature will move you toward the nearest planet unless you do something to stop it, and it will do so without applying any forces at all.

We think of gravity as a force; it is convenient to treat it that way in order to solve equations using Newtonian methods. But it is not a force. It is a spacetime curvature that results in an acceleration with no force. A force must be applied to resist that acceleration.    

Answer 6

place a ball on a rubber sheet

Answer 7

Gravity warpes spacetime!

http://upload.wikimedia.org/wikipedia/co...

And rotating objects not only warp spacetime, they also drag it around them in a process called frame dragging!

http://einstein.stanford.edu/Library/ima...

Answer 8

Think of space as being composed of cells, each of them connected to a great many neighbor cells. Each cell exists in 11 dimensions: space (3), time (1), linear momentum (3), angular momentum (3), and mass/energy (1). The total 11-dimensional volume of any cell is exactly the same as that of any other cell. When a cell is occupied by mass/energy or by momentum, the length of the cell in such dimensions can be said to have increased. To conserve the fundamental volume of the cell, then, some of the other dimensions must shrink.

Because mass interacts with space - space mediates the potential energy that couples mass with other mass - the region of space near mass is significantly affected by the presence of the mass. Consequently, time runs slow near mass, relative to observers farther away. Likewise, mass curves space in its neighborhood. Since momentum (and all its time derivatives) also curves space to a lesser extent, there are such high-order effects such as the Lense-Thirring effect, or "frame dragging."

Answer 9

I confess I have no idea.  But people who are very smart says it does and other very smart people agree with the first group. So whenever the question comes up I will happily say the gravity curves space time.  I am well trained.  

Answer 10

         The problems with this curved space-time view are several. But the most basic of them all is that a body at rest in a gravitational field has no cause to commence motion because curvature does not induce motion unless a force acts. For example, if “curved space-time” were visualized as a rubber sheet with a dent, then a body at rest on the side of the dent would remain stuck there unless a force (such as gravity underneath the rubber sheet) acted to make it move. In open space with no gravity acting, the body would have no sense of which direction was “down” and no reason to move.

Answer 11

Matter warps space-time which gives the illusion of what we call "gravitational force from a distance" when it influences the paths of least energy of other objects.

Answer 12

think of a flat rubber sheet...

then put a rubber ball in the middle (representing a solar body such as the sun) the dent you see in the sheet is curvature caused by gravity.

it's a very crude example, but it works to help our human minds understand the concept of gravity.