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Newton vs. Einstein Gravity Explained

A basic understanding of gravity has been part of human thought for thousands of years. As early as the 8th century B.C.E Indian philosophers were exploring the idea that the falling of an object was caused by some interaction between the Earth and the object. By the time Newton wrote "Prinicipa" in 1687 outlining the rules for gravitation, he was building on a substantial body of work by Galileo, Aristotle and others. For more than 300 years, Newtons Laws ruled supreme, providing almost perfect descriptions for the movement of planets (Mercury being a bit of a problem child, its orbit precedes too quickly for Newton.) and describing the movement of falling objects in a vacuum. Then, early in the twentieth century Newton was tossed aside in favor of the work of a then unheard of German, named Albert Einstein. Why?

The problem with Newton and everyone else before Einstein was not that their calculations weren't accurate. In all but special circumstances Newton is still used today because his equations are so much easier to solve. The problem was with why Newton believed gravity occurred. Newton and those before him, assumed that gravity, like all other energetic phenomena in the observable universe was the result of a kind of force; that there was a "power" inside all things with mass that made them fall together.

In most cases, it doesn't matter why gravity works only how. Occasionally though, as man began exploring large and small scale structures of the Universe, things did not add up to Newton. Enter Einstein. His world shaking, almost impossible to solve equation for gravitation (it requires ten separate, complex equations) really relies on a very simple change in thinking. There is no "force" of gravity. Gravity as we see it is nothing more than space itself being "bent" by the massive objects in it. When one object falls toward a more massive object it is really just "rolling down hill" on the curve created by the more massive object. It fixed the problem with Mercury, solved a number of other gravitational quandaries and is part of the reason why Einstein is a house hold name.

This isn't just theory. Several experiments have proven Einstein correct. The most famous of these is the issue of gravitational lensing. Sometimes light from a further object will be pulled around a nearer object (usually two galaxies) so that the light from the further galaxy forms a halo around the nearer. Since we know light travels only in straight lines, the space that it is traveling through must be deformed in order for us to see the halo. Einstein's deformed space.

This isn't the end of the story though. There are places in the quantum world, very small spaces, where Einstein's rules don't apply. Somewhere out there, maybe typing away right now is the next super-genius who will explain quantum-gravity to us and so eclipse both Einstein and Newton.

References:

www.Wikipedi a.com
www.physnet.org

Learn more about this author, Joel Stottlemire.
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