Questions tagged [dark-energy]
Questions regarding the as-yet-unknown energy permeating the universe that is responsible for its expansion.
72
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1answer
156 views
What are GEODEs?
Phys.org's Researchers predict location of novel candidate for mysterious dark energy says that GEODEs may explain the dark energy problem. I'm not an astronomer but I've never heard of GEODEs. I know ...
1
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1answer
36 views
Does the critical density of the Universe also include Dark Energy?
It is often said that it seems that the Universe is quite close to critical density (for example https://astronomy.swin.edu.au/cosmos/C/Critical+Density).
Does this include Dark Energy as well (apart ...
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1answer
126 views
What is dark energy made of? [duplicate]
What are the fundamental constituents of Dark Energy?
Can we quantize dark energy in the first place, if it is a kind of Energy?
2
votes
1answer
61 views
When will all other galaxies become not visible from Earth/Milky way?
I know that because of the universe expansion, at some point we will not see any other galaxies from Earth, and we will be able to see only our own galaxy.
Does anyone have an origin or time ...
2
votes
1answer
69 views
Was Guth inflation propelled by what we now call “Dark Energy”?
The more powerful our telescopes become, the more we are able to see earlier and earlier remnants of Guth Inflation. Assuming that it makes sense to associate a location, BB, in space-time where the ...
2
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0answers
53 views
Definition of space - to cope with “space expansion”
I've searched quite a lot but found no satisfying definition, so please:
How do we actually define space when talking of "space expansion"? Isn't it just a metric, a dimension we measure, instead of ...
2
votes
1answer
111 views
Why dimmer high-redshift supernovae means the expansion is accelerating, if the dilated region pertains the distant past?
I must be seeing this wrong, because it seems to me the data indicates faster expansion in the past, contrary to Adam Reiss' study that led to the birth of the notion of 'dark energy'.
In Reiss' ...
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0answers
45 views
Could the impresssion of a accelerated expansion of the universe come from a loss of energy of light on a large scale of time?
How do we know that redshift is not the result of energy loss or wave expansion of light on a large scale of millions of years that we have never been able to observe? How can we exclude the ...
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0answers
25 views
Formula to Compute sigma8 for correction in non-linear regime
I try to explain my issue on this forum since it seems to be appropriate.
I need to apply a correction on $\sigma_{8}$ between linear and non-linear regime to keep it fixed (I make change the values ...
8
votes
2answers
724 views
How exactly will DESI simultaneously capture individual spectra from 5,000 galaxies using optical fibers?
The BBC News article Telescope tracks 35 million galaxies in Dark Energy hunt says:
The aim of the five-year programme is to shed light on Dark Energy - the mysterious force thought to drive an ...
1
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2answers
113 views
The origins of Dark Matter/Dark Energy
Layman here with an affinity for astronomy, space and everything associated with it. I'm a big fan of the space oriented programs on the Discovery and Science channels and I was watching an episode ...
3
votes
1answer
106 views
Can expansion of space blueshift galaxies with respect to one another?
Suppose we have two galaxies in an otherwise devoid space, and suppose the galaxies are gravitating. Suddenly, dark energy kicks in, and accelerated expansion of space begins ...
(1D force diagram. ...
2
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1answer
114 views
The energy density of DM (to be fluid,state parameter=-2)increases with time. Does it violate the concept of accelerating universe?
We know that dark energy with value of state parameter $\omega<-1$ is called phantom dark energy model. In this model if we assume dark energy to be a fluid with value of state parameter $\omega=-2$...
2
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2answers
120 views
Can dark energy or dark matter affect black holes
I was wondering if black holes are the greatest force of gravity how does other highly spoken about concepts such as dark energy or dark matter compare. Can a black hole absorb dark energy or dark ...
4
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1answer
108 views
Dark energy and light red shifting
When light is red shifted from distant galaxies, the photons have lost energy. When dark energy pushes objects apart, those objects have gained energy from a larger gravitational potential. Is the ...
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votes
1answer
109 views
In what form was dark energy stored 6 billion years ago?
Bearing in mind the provisions of the 1st Law of Thermodynamics, which decrees that energy can neither be created nor destroyed, all the energy in the Universe must have been there at the time of the ...
1
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0answers
51 views
How are constraints on dark energy improved the most?
Today we have various data available from independent probes to constrain dark energy, i.e. its equation of state $w$. These include Type 1a supernovae, BAO, CMB, large-scale galaxy surveys, etc. Are ...
4
votes
1answer
222 views
Has the Big Crunch been ruled out?
If the dark energy equation of state $\omega$ evolves with time, and becomes larger, this would result in decelerated expansion and eventually a Big Crunch. If $\omega$ decreases with time, becoming ...
1
vote
2answers
136 views
If objects don't move when the universe expands, how can the expansion result in redshift?
I am approaching this topic from a layman's perspective and view this as a logic puzzle, but when someone tries to get me to accept the logic, I'm never convinced by their arguments.
According to ...
2
votes
1answer
136 views
Are gravitational waves part of dark energy?
Do the current models of the universe consider the energy release of gravitational waves?
E.g. iirc, the last black hole merger detected had a gravitational wave energy equal to ~3 solar masses (hope ...
6
votes
1answer
95 views
Can the Dark Energy be Pauli pressure?
Some neutrinos are fermions. There are quite of few of them out there. Could their degeneracy pressure give rise to an expansion force to explain Dark Energy?
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1answer
104 views
What was the process of calculating how much darkmatter/matter/dark energy the observable universe consists of and how did it come at this conclusion
In 2015 the Planck satellite consortium released an analysis of data collected by the Planck satellite that showed this percentage break down of the universeās mass/energy.
Ordinary matter: 4.9%
...
2
votes
1answer
93 views
Can eternal inflation and gravity explain dark energy?
First of all, I have absolutely no background in astronomy and physics. I just watch a lot of "i-hope-scientific" youtube channels talking about physics and astrophysics and I can kind of follow the ...
0
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1answer
112 views
Are there Dark Stars
In the visible universe, we have a lot of matter to energy conversion going on in stars. Is there an equivalent structure that is converting dark matter to dark energy?
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1answer
150 views
What is the closest candidate for Dark Matter currently?
I've both fascinated and frustrated after learning about the existence of Dark Matter.
Can we find evidence of Dark Matter within our Solar system? What is currently the closest candidate for Dark ...
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4answers
310 views
Influences from outside the observable universe explaining dark energy and expansion?
Could some influence from outside the observable universe be causing the expansion?
2
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1answer
62 views
How might WFIRST help us better understand dark energy?
In the video linked in the Space.com article What Would It Mean for Astronomers If the WFIRST Space Telescope Is Killed?, (available in YouTube as WFIRST: The Best of Both Worlds) after ...
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2answers
337 views
Does gravity repel when dark energy is involved?
So I am currently reading the book We have no idea by Jorge Cham and Daniel Whiteson.
In one of their chapters they talk about how gravity is a force that only attracts and doesn't repel, most of the ...
2
votes
2answers
729 views
Relationship between Dark Energy and Dark Matter
I have encountered two seemingly contradictory theories on this(I don't know which one of them is correct, or where I am wrong):-
From Wikipedia:
Measurements of cosmic microwave background (CMB) ...
2
votes
1answer
259 views
What is the distribution of dark energy?
Dark matter is not distributed evenly. It forms clouds, it concentrates in galaxies, it forms hairs around celestial bodies.
A google search for dark energy distribution floods me with dark matter ...
3
votes
3answers
488 views
How does dark energy remain constant?
According to cosmological constant, dark energy should have a constant density but since the universe is expanding so is the volume of the universe and so should the mass of dark energy.
But how does ...
2
votes
1answer
137 views
How strong is the gravity from half of the distant universe?
I would like to know, how strong would the gravity be from the distant universe if we were somehow able to remove half of it. For example, if everything behind us did not exist, how strongly would ...
0
votes
1answer
262 views
How strong is the gravitational stretch we experience from the edge of the universe?
How much gravitational effect do we experience (e.g. maybe -.00001 G or smaller) from the edge of the visible universe? By edge of the visible universe, I am talking about the region of the cosmic ...
2
votes
2answers
158 views
Could Dark Energy be a “Cosmic Gravity Background”
Could dark energy (the accelerating expansion of the universe) be the result of gravity from the dense past universe "pulling" outward from all directions? The universe theoretically started out ...
4
votes
3answers
289 views
Why is dark energy density given in grams per cm$^3?$
According to Wikipedia article,
The density of dark energy ($~ 7 Ć 10^{ā30} g/cm^3$) is very low, much less than the density of ordinary matter or dark matter within galaxies. However, it comes to ...
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votes
2answers
328 views
Are they talking about the observable universe or the unobservable universe? [closed]
When people say that 95% of the universe is dark matter and dark energy, are they talking about it being in the observable universe or the unobservable universe?
Because surely all matter in the ...
0
votes
2answers
103 views
How do you measure something that has already left the observable universe?
They say that the observable universe is only 5% of the entire equation. The rest of it consists of dark matter and energy. I believe that they are trying to find a way to see something that cannot be ...
4
votes
1answer
111 views
Can the diminishing energy of the CMBR be the source of dark energy?
I was just told the CMBR energy diminishes with time. Can it be that the lost energy is somehow transferred to spacetime, causing the expansion to accelerate?
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1answer
1k views
Can virtual particles be the source of dark matter and dark energy? [closed]
I had this question for a long time. But otherwise the question basically sums the whole thing up.
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1answer
111 views
How can space expand in accelerating speed when dark energy is constant?
I came to know that dark energy is constant.As mentioned in the Friedmann equations
How can a constant energy cause an ...
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votes
5answers
1k views
How is the Universe's Expansion Accelerating if the Hubble Constant is Decreasing?
I am just getting into the field of cosmology and was wondering what it means practically to say that the Hubble Constant is decreasing while the expansion rate of the Universe is accelerating. I am ...
2
votes
1answer
216 views
Why can we trust Hubble Time if the rate of expansion is not constant?
The age of the Universe can be estimated from taking the inverse of the Hubble constant: $t_\text{universe} = 1/H_0 =d/v.$
It seems to me this method assumes that any given galaxy has been receding ...
0
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1answer
134 views
Could dark matter be “inside-out” reality?
Where we are, and in the conventional galaxies etc. that we see, there is a whole lot of relatively uniform space but in isolated places within that space, there are pockets of concentrated "mass" ...
3
votes
2answers
157 views
Is there any proof of space being created?
Is there any proof for space being created?
Because I guess an explanation for the dark energy (dark = our understanding of it) could be that there is a gigantic amount of matter/dark matter that we ...
0
votes
1answer
228 views
Is nucleosynthesis responsible for the expansion of the universe?
Is it just a coincidence that the two major expansionary periods occur close to periods of nucleosynthesis?
Big Bang nucleosynthesis occurred very close to the inflationary period.
Supernova and ...
11
votes
1answer
472 views
Will gravitational waves too far away ever reach us?
Gravity is the curvature of spacetime, and its effects travel at lightspeed. However, space is expanding; eventually, light from distant galaxies will become more and more redshifted, and we will no ...
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3answers
266 views
Can “dark matter” be the additional mass from the speed of the Galactic Cluster?
Considering that the Earth orbits the Sun at 100 000 km/h and that the Sun orbits the Milky Way at almost 1 000 000 km/h, could it be possible that the galactic cluster orbits some super cluster at ...
1
vote
1answer
139 views
What's the relation between Einstein's Gravitational Theory and Dark Matter?
I was reading an elementary book on dark matter (in fact, a historical perspective) and there were mentioned how the scientific community react to the idea of dark matter proposed as a solution to ...
0
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1answer
928 views
If the Universe is infinite, would heat death be impossible?
If the Universe is infinite, one would imagine that if we kept moving through space, we'd constantly find newer and newer galaxies and objects forever. This would imply that there is an infinite ...
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1answer
435 views
could dark energy be a force coming from the hyperspace outside the universe?
It seems to me that the expansion of the universe is only being looked at one way. a repelling force, basically being the opposite of gravity. After pondering this for many nights, I began to wonder ...
