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Science Over the EdgeA Roundup of Strange Science for the MonthApplet credit: Ed Hobbs
April 2007 |
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Quantum Mechanics is one of the two great physics theories of the 20th century that replaced classical (Newtonian) physics. The other was General Relativity. Interestingly both were fathered by the same man: Albert Einstein. While he loved the one child the other was disliked. Einstein never felt comfortable with Quantum Physics. General Relativity is mostly used to describe how the world of big things work: The movement of planets, stars, rockets, etc. Everything down to about the size of an atom. Below that size scientists almost always use quantum physics to do their calculations. Both were needed as classical physics created by Issac Newton in 17th century couldn't predict how the things worked when dealing with extremely large objects (like planets and stars) or extremely small objects (like photons and electrons). While the rules of general relativity seem to make some kind of sense to us, the rules involved with quantum physics are bizarre and challenge our understanding of reality. Little in this realm is for certain. Everything is based on the probability of something happening. This is one of the reasons Einstein disliked it. He has often been quoted as saying, "He [God] does not play dice" with the universe.
So I guess light is a wave them, huh? If you close one of slits, though, suddenly light starts behaving like a particle again. We see it piling up behind the open slit. Well, maybe light only behaves like a wave when a lot of light particles are moving together. Unfortunately this is not the case. When the double slit experiment is performed sending only one photon (light particle) though the barrier at a time the photon doesn't show up behind the slits. It can show up anywhere on the screen. In fact, as you send more and more photons though the experiment one at a time the interference pattern slowly builds up, just as before. Does that mean that each individual photon is a wave that interferes with itself? Yep. Does this mean that the photon passed through both slits at the same time? Indeed, this seems to be the case. When scientists have placed photon detectors at each slit to see which side the photon goes though a strange thing happens. Suddenly the interference pattern disappears and there are just two lines of light one behind each slit. The detector has somehow forced the photon to stop behaving as a wave and act like a particle again. Even if the detector is placed on the opposite side of the barrier, after the photon passes though the slits, the photon still acts like a particle. How did it know that there was going to be a photon detector on the opposite side of the barrier so it would behave like a particle and not a wave when it passed though the barrier? In the end, light is both a wave and a particle at the same time. If you think that doesn't make sense, you are right. However, that doesn't change the fact that it is true. If you can explain why all this happens and support your ideas with experimental proof, you're probably on your way to a Nobel prize. This is just the tip of the iceberg when it comes to Quantum Physics weirdness. As you get deeper and deeper into it what you find seems to make less and less common sense. You might try to argue that scientists simply have gotten the thing wrong except that quantum theory is one of the most successful theories of all time and is used in the design of such everyday things as TVs and cell phones. Experiments show that not just light is both a particle and a wave, so are electrons, protons and atoms. These maybe small things too, but remember we are just made of atoms. At some level are we just waves too? Scientists have grappled to figure out what this means in the real world. Some interpretations include the ideas like "nothing is real until it is observed" or that there are countless "multiple universes" each differing just slightly from the one next to it. There isn't room here to discuss all the ramifications of quantum theory, so I'm going to give you a couple links that may help. Prepare to see the world in a different light after reading these, or at least have an awful headache: http://www.thekeyboard.org.uk/Quantum%20mechanics.htm and http://en.wikipedia.org/wiki/Quantum_mechanics
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