General Relativity
Created | Updated Feb 17, 2002
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General Relativity (which is basically Special Relativity in acceleration fields) isn't easy. In fact, next to super strings, it is the hardest thing to learn on this wet little planet (well actually, memorizing all those stupid body parts in anatomy is harder).
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General Relativity can be best summarized by saying that gravity doesn't really exsist. Instead, mass/energy (which is the same thing), curves space, and that particles follow geodesics (the fancy way of saying shortestpath, or in general relativity, longest path) on that (four dimensional) surface.
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The basic math for this has been known since the mid 1800's by a guy named Riemann. He invented the mathematics of higher dimensional curved spaces. In fact, he found out that you could completely define everything if you know the metric (the formula telling the distance between two points, written in differential form) of the surface. You can then use something called tensor analysis, along with some really good intuition to find that the equation for gravity looks really simple. In fact, it is about the size of Newton's gravition equation if you count the number of symbols. I must emphasize that it <I>looks</I> simple, because if you expand that one little line out in terms of the metric equation, you get several independent equations all so big that after an hour of expanding one of them I lost patience and decided that playing with paper clips was much more exciting.
General Relativity (which is basically Special Relativity in acceleration fields) isn't easy. In fact, next to super strings, it is the hardest thing to learn on this wet little planet (well actually, memorizing all those stupid body parts in anatomy is harder).
</P<P>
General Relativity can be best summarized by saying that gravity doesn't really exsist. Instead, mass/energy (which is the same thing), curves space, and that particles follow geodesics (the fancy way of saying shortestpath, or in general relativity, longest path) on that (four dimensional) surface.
</P><P>
The basic math for this has been known since the mid 1800's by a guy named Riemann. He invented the mathematics of higher dimensional curved spaces. In fact, he found out that you could completely define everything if you know the metric (the formula telling the distance between two points, written in differential form) of the surface. You can then use something called tensor analysis, along with some really good intuition to find that the equation for gravity looks really simple. In fact, it is about the size of Newton's gravition equation if you count the number of symbols. I must emphasize that it <I>looks</I> simple, because if you expand that one little line out in terms of the metric equation, you get several independent equations all so big that after an hour of expanding one of them I lost patience and decided that playing with paper clips was much more exciting.
