Dark energy is the unknown form of energy that drives the acceleration of the universe's expansion.
Questions tagged [dark-energy]
605 questions
56
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4 answers
Are modified theories of gravity credible?
I'm a statistician with a little training in physics and would just like to know the general consensus on a few things.
I'm reading a book by John Moffat which basically tries to state how GR makes failed predictions in certain situations. I know GR…
dcl
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What are the alternative theories of dark energy? ($w \neq -1$)
There has been a lot of related questions about dark energy around here but these are usually 2-4 years old and the closest question to mine hasn't really been answered, so I am going to proceed. Experts may skip to the last paragraph, but I am…
Void
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How do people calculate proportions of dark matter, dark energy and baryonic matter of the universe?
The Wikipedia page on dark matter mentions that the Planck mission had revealed that in our universe ordinary baryonic matter, dark matter and dark energy are present in the ratio: 4.9%, 26.8% and 68.3% respectively. I do not understand exactly how…
curious
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Why does dark energy produce positive space-time curvature?
My understanding is that dark energy, or equivalently a positive cosmological constant, is accelerating the expansion of the universe and I have read that this gives empty space-time positive curvature, ie de Sitter geometry. I also understand that…
Daniel Mahler
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How did the universe shift from "dark matter dominated" to "dark energy dominated"?
In order to get dark energy to dominate, wouldn't you first need another form of energy to push the expansion until dark energy could dominate? Otherwise I don't understand how the universe could shift from having a decelerating expansion to an…
user43783
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What experiments, other than Hubble Expansion, support the Dark Energy theory?
Dark energy is introduced as a constant inside Einstein's equations. Its primary purpose, from what I understand, is to make Einstein's equations compatible with the accelerating expansion of the universe. As a consequence, of the "predictions" of…
Malabarba
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If gravity is attractive, why doesn't the Milky Way contract?
Einstein introduced the cosmological constant because without it, one cannot get a static universe - gravity would cause the universe to contract.
Given that, why is the Milky Way not contracting? For that matter, why isn't the Solar System…
Allure
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Dark matter and dark energy references
I've been looking for questions about dark matter, and I've read some very interesting answers. However, I desire too look into it deeply.
This is not actually a question. I'm asking the community to recommend interesting references to…
deps_stats
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Why do we interpret the accelerated expansion of the universe as the proof for the existence of dark energy?
Why do we interpret the accelerated expansion of the universe as the proof for the existence of dark energy?
The accelerated expansion only tells us that the Einstein field equation must contain a cosmological constant, but I can put the constant…
RenatoRenatoRenato
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Does time expand with space? (or contract)
Einstein's big revelation was that time and space are inseparable components of the same fabric. Physical observation tells us that distant galaxies are moving away from us at an accelerated rate, and because of the difficulty (impossibility?) of…
Loourr
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What is Dark Energy, and how was it discovered?
I've heard a lot about Dark Energy, and how it's supposed to be one of the most powerful forces in the universe. What is it, and how was it discovered?
PearsonArtPhoto
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How is dark energy consistent with conservation of mass and energy?
I initially thought that dark energy must in some way violate conservation of mass and energy since the component of the energy density of space that comes from dark energy is constant, and space is expanding. Therefore, as space expands the energy…
Deets McGeets
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Why is dark energy dominant between galaxies but not inside galaxies?
The ideas of dark matter and dark energy are mind blowing.
Why is it said that dark matter overcomes dark energy in galaxies but it loses the battle in intergalactic space? In other words, why is dark energy dominant between galaxies but not inside…
Ebi
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How do scientists calculate the percentage of dark energy in the universe?
I can understand how the percentage of dark matter compared to ordinary matter is calculated, because the amount of dark matter has a clear gravitational effect on the ordinary matter in a Galaxy.
However, calculating the percentage of dark energy…
ODP
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Is there a distance from a gravitational source where the influence of gravity and dark energy are balanced out?
While gravity is a force that attracts
objects with mass, dark energy (or, alternatively, the accelerated expansion of the universe) is not.
However, I have found numerous articles, forums, questions in the stack exchange network... where people…
vengaq
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