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Full Member
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Jul 27, 2009, 10:14 AM
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1st law of thermodynamics confused!
The 1st law of thermodynamics states that energy can be in many different forms, but cannot be created or destroyed.
But in einstein's equation E=mc^2, you can convert something as little as a penny into enormous amounts of energy. Wouldn't that be "creating" energy? Or is the energy already there, but in different form like the law says?
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Uber Member
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Jul 27, 2009, 11:51 AM
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The energy is stored in the form of matter, if you see what I mean. You are not creating energy. Even I don't quite understand this, but it seems that matter is 'chemical energy', together with 'potential energy', etc.
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Expert
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Jul 27, 2009, 12:15 PM
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Einstein showed that matter and energy are two forms of the same thing. So yes, matter can be turned into energy and vice versa, without violating the 1st law.
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Full Member
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Jul 27, 2009, 01:58 PM
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So, in the whole universe, energy is never created? Even when stars go supernova, etc. energy is always constant? WOWWW, that's cool
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Expert
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Jul 27, 2009, 02:12 PM
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That's the theory! Can it be "proved" that energy is never created nor destroyed? No, but so far no one has ever observed a violation of this "law," at least not with respect to every day events. However, there are some interesting implications in the area of quantum mecahnics - given that the Heisenberg Uncertainy Principal states that there is a certain amount of uncertainty of a particle's momentum, it follows that there is uncertainty in that particle's kinetic energy. And hence it may be that energy is not necessarily constant over extremely short periods.
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