Questions tagged [energy]
Energy is the conserved quantity associated to time-translation invariance and represents the work a system is capable of doing. Use this tag for questions about energy, and consider adding the [energy-conservation] tag if it is specifically about its conservation.
7,506 questions
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Questions about Jean-Rayleigh's derivation of Ultraviolet Catastrophe
I am following this video and; Eisberg and Resnick's Book for this derivation, for I cannot find other sources that go as in-depth as they do. $\Large\text{Question 1)} $ Jean's cube, or the metallic ...
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Energy conservation in a travelling wave
I have understood the proofs for how KE and PE per unit length of a travelling wave are equal. But I am unable to get a clear understanding of how energy is conserved in the wave. If both the ...
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Can vacuum shift to a higher energy level?
From this, I gather that a false vacuum can decay to a false vacuum of a lower energy. AFAIU vacuum decay is always local, propagating at the speed of light (whence the reference to the expanding ...
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Relation between kinetic energy/momentum and space/time [closed]
I would like to understand kinetic energy and momentum better. Especially how they are related to space and time. The momentum of a particle equals the impulse that accelerated it from rest to its ...
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How cold would it “feel” floating in space in Earth’s orbit? What`s the “effective temperature”?
So, space is cold but there is very little particles to transfer heat away from you in near vacuum. At the same time, the Sun is able to heat the surface of the Earth to temperatures of 50+ degrees ...
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Relationship between momentum and probability current in Dirac equation
I would expect that for a given eigenstate with energy $E$, the density of momentum $\mathbf{p}$ and the probability current $\mathbf{j}$ at any point would be related as: $\mathbf{p}=\frac{E}{c^2}\...
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Kinetic energy and reference frames [duplicate]
Speed is relative i.e. different frames of reference can measure different speeds of a body. This means that kinetic energy is also relative. So does it mean a frame of reference can measure the ...
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Which laws of nature prohibit harvesting neutrino energy?
Updated in response to comments There is an old question on Skeptics SE, "Can electricity be obtained from neutrino radiation, like a solar cell?". It's about a company's claim to have the ...
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Derivation regarding Gibbs free energy
I'm a beginner, learning things like entropy and gibbs free energy for the first time. I'm trying to derive the famous equation: $$ΔG=ΔH-TΔS$$ but it looks like I'm getting nowhere. I start by ...
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¿Que tan posible seria liberar y materializar energia interna como dice a continuación? [closed]
La Liberación Controlada de Energía Interna para la Generación de Fuerza Física: Propuesta Teórica de un Sistema de Control Biocuantico Autor: Thiago [Apellido] Resumen Este trabajo explora la ...
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Which photons count per second? [closed]
Since light interferes with itself constructively or destructively, is it more accurate to understand the relation between an increase of intensity (and therefore amplitude) and the number of photons ...
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Stability of Superposed States [closed]
I am wondering if the superposition of harmonic oscillator stationary states always leads to a stable system or whether there exists the possibility of a spontaneous transition to an eigenfunction of ...
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Hubble's Law and the age of universe
Hubble's Law says that galaxies are moving away from Earth at speeds proportional to their distance. The resolution of Olbers' Paradox is that the universe is of finite age. However, Hubble's ...
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Consideration of the consequences of the conflict between the existence of anything and the second law of thermodynamics
Firstly, this question sort of jumps off of another question asked a while back: Does the existence of matter and energy in the universe violate the second law of thermodynamics? In essence, based on ...
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Why Does an Electron Emit a Photon? [duplicate]
I've seen similar questions asked, but I didn't think they were quite the same. My understanding, and it is probably an incorrect one, is that an electron in an orbital shell has a stable balance of ...
