2007-02-24 01:58:58 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
Think about a cloth having grids of lines printed across it. and u put a ball on it. the centre of the cloth will be depressed by the weight of the ball and the grid lines will appear to be curved. The heavier the ball, steeper will be the curvature of grid lines. This curvature is nothing but gravity of that ball with respect to the cloth. So, earth also curves the space and time around it. By virtue of its "mass", the space-time continum is curved around it. The curvature of this curve is called gravity. If u put a lighter ball on the cloth, u'll find it is moving towards the heavier ball at the centre. Higher the mass of the center ball steeper 'll be the curve and the lighter ball will move faster towards it. If u move away from the centre then the curves will be flat so gravity is not felt in space. So a body curves the space and time around it called the space time curve.
2007-02-25 04:55:51 · answer #1 · answered by Anonymous · 0⤊ 0⤋
If I plot the trajectory of a home-run baseball as a curve in 4D spacetime, that would be a "spacetime curve" or spacetime trajectory. We already do this for simpler cases, such a ball thrown straight up in the air, which falls back down. The 2D "spacetime curve" would be a parabola where time t would be a parameter. The 4D case is harder for people to visualize, but it's just a generalization of the simpler 2D case.
In general relativity, objects in free flight follow spacetime curves that must obey certain mathematical properties, mainly that it be a spacetime geodestic. If spacetime was "llat", then it'd just be a straight line, but real spacetime is not flat, so geodestics tend to curved. If you want to fly "straight to London", your plane will not be going in a straight line, but a geodestic on the sphere called the great circle. Mass warps spacetime, so that geodestics are frequently spacetime curves that are "bent" towards such masses. In the case of the hit or thrown baseballs, they are actually 4D spacetime geodestics, which is why they look like they're being "pulled" down by gravity.
2007-02-24 02:15:48 · answer #2 · answered by Scythian1950 7 · 0⤊ 0⤋
Also called a "world line", it's the path that an object follows in space-time. In other words, its history and future as to where it is at each time.
Often this is shown on a graph, with one axis being "time" and the other axis being "distance". Of course, a real object's space-time curve would need 4 axis to graph: 1 for the time axis, and 3 for the X, Y, and Z positions.
2007-02-24 02:11:18 · answer #3 · answered by morningfoxnorth 6 · 1⤊ 0⤋
If you draw a curve on a two-dimensional grid, it accelerates in either the x or y dimension. If in curves in the x dimension but stays the same in the y, it's a parabola. Gravity is the same thing. In four dimensions (including time), an object will fall to the ground, increasing in speed. It accellerates in two dimensions, but maintains a straight line in the other two.
2007-02-24 03:03:32 · answer #4 · answered by Anonymous · 0⤊ 0⤋
I think the answer you are looking for is Gravity.
Einstein postulated that the Universe is made up of a space-time continuum. The existence of matter causes a curvature in this space time (the common example is a weight on a stretched rubber sheet) and this curvature is what we experience as gravity.
2007-02-24 02:06:19 · answer #5 · answered by davidbgreensmith 4 · 1⤊ 0⤋
"Morningfoxnorth" has the correct answer.
2007-02-24 04:58:49 · answer #6 · answered by stargazergurl22 4 · 0⤊ 0⤋