All Questions
Tagged with cosmology energy-conservation
131
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Dark energy and conservation of energy in General relativity [duplicate]
i know that conservation of energy in general relativity has been discussed multiple times here at PE, a popular explanation on the topic is Sean Carroll's blog "Energy is not conserved" ...
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Why is the First Law of Thermodynamic related to Fluid Equation?
In Cosmology, there is a equation called Fluid Equation:
$$\dot{{\varepsilon}}+3\frac{\dot{a}}{a}(\varepsilon+P)=0.$$
It is derived by taking time derivative of the First Law of Thermodynamic:
$\dot{E}...
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What is the total mass-energy of baryonic matter?
From what I understand, conservation of energy does not apply to the total energy of the Universe, because it constantly expands and the new, created space has a constant non-zero energy of its own. ...
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Does the energy of a photon in comoving space change?
Assuming a flat FLRW universe that is expanding: In comoving space, does the energy of a photon decrease or stay constant? A physical argument for this would be nice.
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Are there structures or systems that can have a high angular momentun that are not made by protons and/or neutrons?
Cosmic structures such as neutron stars, white dwarfs or black holes can have high amounts of angular momentum (high spin velocities). However, these are all made by protons and neutrons (black holes ...
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Noether's Theorem in relativistic cosmologies [duplicate]
Is Noether's Theorem valid within the context of relativistic cosmology? If not, does this mean that the universe does not conserve energy on cosmological time and distance scales?
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Different types of Dark energy and conservation of energy
According to this Sean Carroll article, and other threads in here, depending on your definition of energy, dark energy does not violate conservation of energy. My question is if this is true ...
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Does dark energy get used up in the expansion of the universe?
Now, I am a beginner in Cosmology, so I am not sure if this makes sense.
Since the universe is expanding at an accelerating rate, and thus distant objects are also accelerating away. In that sense, ...
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Expansion of Universe and validity of law of conservation of energy [duplicate]
It has been proved by the Red Shift that universe is expanding. But if the universe is actually expanding, it needs energy to do so. I also do not know that with expansion in universe if mass ...
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Violation of energy conservation: cosmological Doppler-effect in what might seem an inertial frame of reference
I've seen disagreement about whether the cosmological Doppler-effect violates conservation of energy. It can be complicated to analyze since there is no reference frame of a photon.
My question is: ...
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Could the energy emitted by galaxies contribute to the dark matter phenomenon?
I'm pondering a concept regarding the energy-mass conversion in the context of cosmology, specifically related to the light emitted by galaxies over billions of years.
Einstein's famous equation E=mc^...
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When light gets red shifted by the expending universe it's energy decreases. What happens to that energy? [duplicate]
If a Photon of light is red shifted its wavelength increases and therefore its energy decreases. What happens to that energy as energy should be conserved right?
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Can gravitational waves gain energy in an expanding FRW spacetime?
I was reading this paper (Green's functions for gravitational waves in FRW spacetimes: https://arxiv.org/abs/gr-qc/9309025) I had a specific question about one statement in the paper that I would like ...
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*Observational* Consequences of Energy Nonconservation in GR
What are the experimental or rather observable consequences of the non-conservation (or conservation) of energy in GR? Imagine our instruments were $10^3$ or even $10^6$ more sensitive, better ...
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The gravitational field of all the distant mass exactly cancels the positive mass-energy in the universe. Why do they think so? [duplicate]
It is often said that the gravitational field has negative energy, and that this negative gravitational energy of all the distant mass exactly cancels the positive mass-energy in the universe.
Why do ...
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