Timeline for If energy is relative, then how it can remain conserved?
Current License: CC BY-SA 4.0
12 events
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| Apr 28, 2023 at 2:25 | comment | added | naturallyInconsistent | @user253751 It is less confusing to think of rest mass as a form of energy that is rather difficult to convert to and from. The energy of a system in its rest frame of reference is a Lorentz invariant on top of being conserved, and that value is used to define the rest mass of the system. As for converting the mass energy into other forms, particle antiparticle annihilation converts it 100%, dropping something into a black hole does next best at a few percent, and the general other kinds of nuclear reactions convert small amounts but detectable and detected. | |
| Apr 20, 2023 at 21:50 | history | edited | Avantgarde | CC BY-SA 4.0 |
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| Apr 20, 2023 at 12:15 | comment | added | Dale | Proper time is a better example of a type 3 quantity. Proper time is the prototypical invariant quantity, all frames agree on it. But it is continuously increasing, so it is clearly not conserved. | |
| Apr 20, 2023 at 12:13 | comment | added | Volker Siegel | @user253751 I thought the question implies assuming energy is not mass. | |
| Apr 20, 2023 at 12:04 | comment | added | Volker Siegel | Creating mass happens more often in star explosions than on earth, I think. | |
| Apr 20, 2023 at 12:03 | comment | added | Volker Siegel | @user253751 The energy in nuclear fission and nuclear fusion, in weapons and in power plants, comes from mass that is lost. Very little mass. You split a Uranium nucleus, and the resulting particles have a slightly lower mass together than the original nucleus. The Hiroshima bomb converted a little more than half a gram of mass to energy. | |
| Apr 20, 2023 at 11:54 | comment | added | Volker Siegel | @user253751 With nuclear reactions. | |
| Apr 20, 2023 at 3:42 | comment | added | N. Virgo | I understood the question as being something like "if I, the observer, boost myself to another reference frame during the experiment, then the energy of the system I'm observing will seem to change; how can we account for that?" Maybe I'm wrong about that being the question, but I feel the answer would be improved if it would address that. | |
| Apr 19, 2023 at 21:15 | comment | added | Blackhole | @Quant2 That's because you're using the common meaning of "invariant". In physics, "invariant" doesn't mean "something that can't change" (for a given reference, that will rather be "conserved"), it means "something that is the same, at a given moment, for all reference". (I use the word "reference" broadly here, the real definition is with a transformation, which again has, in physics, a different meaning than the common one.) | |
| Apr 19, 2023 at 10:11 | comment | added | Avantgarde | Mass is invariant (it is Lorentz-invariant). This means that it is the same in different reference frames related to each other by Lorentz transformations. But it is not conserved, because it can be created or destroyed. | |
| Apr 19, 2023 at 9:37 | comment | added | Quant2 | I can't understand the the third type physical quantity you mentioned as if a thing is invariant then it would not vary in any time during the experiment, so it can't vary even during the beginning and end of the experiment and so an invariant thing must be conserved. | |
| Apr 19, 2023 at 9:22 | history | answered | Avantgarde | CC BY-SA 4.0 |