Gravity and Space-time?

Question

I've always had trouble understanding this concept. I know that gravity is the manifestation of the curvature of space-time. Only I can't picture what that means. If anybody can, can you explain to me in simplest terms as possible, how gravity is caused by spacetime curving? How does spacetime curving cause people to fall? I don't understand that. I know that somehow space is pushing you down and for some reason the ground comes up a tiny bit when you fall but I don't understand why. Please explain. Thanks.

Answer 1

http://www.youtube.com/watch?v=0rocNtnD-yI&feature=related

Answer 2

i do no longer think of it is often happening no count if area someway "wears out" by utilising being returned and returned curved by utilising pressence of mass. it is complicated to visualise the three-D projection of the commonplace "place a bowling ball on a trampoline" occasion - it may be some thing like this shape, yet repeated in each and every conceivable airplane around the object. (someway, I save imagining a torus shape, yet i know which could additionally purely be a bypass area of the authentic shape of a gravity properly) Gravity is extremely area being curved in a course "perpendicular" to area - which we can not extremely visualize as a results of fact we can purely bypass in 3 guidelines, or some mix of them. Gravity does seem to propogate out from components like ripples do. i do no longer think of it is gravity of another parallel universe it is stretching our area, regardless of the incontrovertible fact that. it is presently proposed that dark capability is the rigidity utilising the upward thrust of area. i'm no longer specific of the data at the back of dark capability authentic now, yet there seems to be data that it extremely exists, a minimum of greater so than for the presence of the aether. So if something's destroying area, cutting-edge theory is that it is the dark capability, which looks greater suitable than gravity. cutting-edge data factors to the top that there is purely no longer any vast crunch, so the universe is predicted to develop until it thins itself into oblivion. stable subject it is not happening next month, eh?

Answer 3

You don't need to understand tensors and Riemann geometry to understand this. You need to understand why Einstein came to the conclusion that the acceleration from gravity is due to space-time curvature.



The basis of General Relativity is something called the equivalence principle. Einstein decided that acceleration due to normal forces (like rocket power) and acceleration due to gravity were indistinguishable from each other. If you are accelerated in a rocket ship, objects that are moving at a constant velocity will look like they are following a curved path. In actuality, the coordinate system (reference frame) of the rocket ship is curved and the the other objects are following a straight line. Since Einstein concluded that gravitational acceleration and acceleration due to other forces were equivalent, he concluded that the acceleration due gravity was due to the curvature of space-time. Space-time itself had an intrinsic curvature due to the presence of matter and was in fact equivalent to an accelerated reference frame.

Answer 4

Great question. You're right in thinking gravity is a geometrical phenomenon. The 2D representation is a starting point for extending the conundrum. But if you are like most, you quickly find yourself trying to visualize 4 dimensions with right angles. The only way this begins making any sense is to first dispense with Euclidean geometry. After that liberation, the mind is free to use other paradigms. Einstein's famous work involves Riemann tensors. Crudely speaking, tensors are extensions of vectors. Vectors are directions with magnitude. A Riemann tensor comes out of metric tensors which tell how to compute the distance between any two points in a given space. With that information, one can begin evaluating curvature, regardless of its physical shape. If the only obstacle in understanding is its shape, drop it like a bad habit. Shape is 100% useless for developing an understanding of tensors. The only thing that has significance is the evaluation. Besides, the surface takes shape in hyperbolic space. Holding on to Euclidean precepts is like fitting a tennis ball in a square hole. As for why gravity causes a body to fall, that has to do with Potential Energy. An object with a large amount of potential energy will accelerate until its kinetic energy is maximized (shhh... regardless of the shape involved). Any body with large mass will produce a potential energy in another object as the separation increases, up to a limit.



EDIT: Some people wait for others to speak up before they have an original thought, a.k.a. jacking the integrity.

Answer 5

Imagine a blanket sheet that is pulled tight on all sides, making it as straight and smooth as possible. From here we can use the example of our sun. Pretend we put a basketball onto the tight bed sheet, and the basketball makes the blanket sheet sag down a little. THIS is spacetime curving. Going on... now that we have the basketball on the sheet, indenting the sheet... we can now imagine why earth is trapped within the orbit of the sun. Imagine taking a small bouncy ball and rolling it around the blanket that is indented with the basket ball. No matter what happens the bouncy ball will fall towards the basketball, right? Now add some velocity to the bouncy ball to the side of the basketball, and you will mimic an orbit.



In short: Heavy things indent space, creating funnels towards themselves. As smaller objects pass by they get trapped or fly straight into the indentation made by the larger objects.

Answer 6

General Relativity is not simple,



geometric theory of gravitation



Earth is moving in a straight path,



we are not



vectors



Laws of Motion



three dimensions of space, fourth is time

Answer 7

http://cosmicshipmedia.net/spacetime/Spacetime_curvature.png



This is the picture they draw to illustrate their speculations. It seems visually appealing because it is so natural for a body to roll downhill. But what pulls the body down against the grid? It can't be gravity because that is what the picture is supposed to explain. It would have to be a new force in the universe, and nobody has detected any such force. There is no other support for this concept of curved space-time, or an other kind of space-time either. We are still stuck at square one: the only thing we know about time and gravity is that we know nothing about time and gravity.

Answer 8

You're not the only one. Get book by Stephen Hawking from library. . I've read it a couple of times, and still don't understand all details. It's easy to read, but you have to let go of nearly everything you thought was logical.

Answer 9

Hmm