Is the law of conservation of energy generally true?
Brian M asked:
I know the conservation of energy can be violated for short times, but not overall. is that right?
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I know the conservation of energy can be violated for short times, but not overall. is that right?
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October 16th, 2007 at 9:47 am
When can it be violated over short intervals?
Energy is concerved (at least as a 4-vector) and space is homogeneous. Pretty much.
October 16th, 2007 at 10:01 pm
It’s totally right. look at how your gas mileage is affected when the air conditioner is on. It’s totally aplicable in every day life but we usually don’t think about such things.
October 17th, 2007 at 2:33 am
Yes, otherwise it would not be called a law. It would be called a theory or theorem.
October 18th, 2007 at 8:52 pm
Definitely it is right. You need not have to doubt that law.
October 19th, 2007 at 3:04 am
Depends on how you think about it.
If you are real famous people will believe everything you say.
Not every law has enough evidence only if you find evidence that is contradictory to the oringinal law.
October 19th, 2007 at 12:25 pm
If our observations are not perfect and during observation if we sleep, then the law will seem to be violated during that short time of our sleep.
October 19th, 2007 at 2:47 pm
Nice question. Everybody says that energy is always and perfectly conserved, but the reality is something else. You are right, it can be violated for short times, within the Heisenburg uncertainity limits, and this has to be figured in calculations in quantum field theories. For example, a gauge boson could momentarily acquire energy out of nothing for the short time of its existence, within quantum uncertainity limits. Professional physicists know all about this, they do the math with this, but for some reason, it’s not relayed to the public.
Now let’s move to the more interesting stuff. Noether’s theorem states that conservation of energy is a consequence of temporal symmetry. That is to say, if physical equations are invariant with respect to translation in time, then energy is conserved. However, that does not mean that everything is invariant with respect to time. In more extreme cases, at the boundary beyond ordinary spacetime as we know, as for example. inside black holes or at Planck dimensions of spacetime (think really tiny now, smaller than even strings), ordinary laws of physics or even time itself breaks down, and energy may not be conserved. And some important equations in physics, such as the relativistic version of the Schrodinger wave equation, called Klein-Gordon equation, energy is not conserved either. So, in answer to your question, yes, the law of conservation of energy is generally true, because generally speaking, we’re talking about ordinary spacetime with nice well behaved symmetries that we’ve all come to rely on for our reality, but such symmetries in fact cannot be taken for granted. There is no fundamental reason why they MUST necessarily exist in all cases, nor there is any mathematical proof of that.
October 22nd, 2007 at 10:19 am
it is true because,
Energy can neither be created nor be destroyed.
It can be converted from one form to energy .