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People love to say, gravity is not a force it is a change in geometry. I was just curious though, einstein showed that a uniform acceleration is equivalent to gravity. The uniform acceleration is caused by a uniform force. So what is the difference between a change in force and a change in geometry.Why is it even necessary for people to say no it is not a force it is altered geometry, whats the difference?

Quote from: thebrain13 on 19/01/2007 06:35:41People love to say, gravity is not a force it is a change in geometry. I was just curious though, einstein showed that a uniform acceleration is equivalent to gravity. The uniform acceleration is caused by a uniform force. So what is the difference between a change in force and a change in geometry.Why is it even necessary for people to say no it is not a force it is altered geometry, whats the difference?A lot, especially the consequences. If it were a Force and the geometry were not warped, that is, were Minkowskian ("flat" in 4 dimensions), then you would find, for example, that a circle's circumference is 2π times the radius. But this is not, near massive bodies. You cannot explain this with forces.

Quote from: lightarrow on 19/02/2007 13:18:39Quote from: thebrain13 on 19/01/2007 06:35:41People love to say, gravity is not a force it is a change in geometry. I was just curious though, einstein showed that a uniform acceleration is equivalent to gravity. The uniform acceleration is caused by a uniform force. So what is the difference between a change in force and a change in geometry.Why is it even necessary for people to say no it is not a force it is altered geometry, whats the difference?A lot, especially the consequences. If it were a Force and the geometry were not warped, that is, were Minkowskian ("flat" in 4 dimensions), then you would find, for example, that a circle's circumference is 2π times the radius. But this is not, near massive bodies. You cannot explain this with forces.Excuse me for asking silly questions, but how do you measure the radius in a strong gravitational field?You could measure that path light takes from one side of the circumference to the other, but this assumes that light is travelling in a straight line. If you remove that assumption, then how do you know what a straight line is, and thus what constitutes the true radius of the circle?You could also suggest that it is the shortest equidistant point from all the points of the circumfence, but in reality you can only say that no point with a shorter distance can be measured, not that such a point cannot exist. If you measure the circumference and radius of a circle drawn on the surface of the Earth, it will not be a ratio of 2π, but that assumes you do not have the technology to tunnel through the Earth, it does not say anything so much about the geometry of space as about the limitations of the technology that bind you to a surface.