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What do membranes have to do with space and time?Physics has been able to explain the movement of balls on a pool table or a stone thrown into the air for a long time. However, new thoeries are required to explain in detail the motion of sub-atomic particles and of very big objects like stars. These thoeries are called quantum mechanics and Einstein's theory of gravity (also often called relativity). Both theories are products of the 20th century and both have proved extremely useful. However, there is a problem: no one knows how to put these theories together. One way that physicsists are trying to do this is called String theory.String theoryThis may sound ridiculous but one way to explain the ideas behind string theory is to imagine that we replace particles by strings - one dimensional (*) objects. Now if you think of a guitar string, particles are like the notes you get from plucking the string. The type of particle or the pitch of the note depends on how tight the string is (stretching energy or string tension).To complicate the picture we can think about how the string moves in time and imagine that it sweeps out a two dimensional (*) surface. To understand this think of the surface of a piece of cheese left as a wire cheese cutter sweeps throuh the cheese. It turns out that the shape of this surface is determined by theories of quantum mechanics and stretching and bending energies like those of membranes. One of particles seen in string theory is the graviton, the particle of gravity. String theory is thought to unite Einstein's theory of gravity with the other particles and forces of nature. The mathematics and physics of these theories is very similar to physics of membranes/soap/red blood cells...
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