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Questions tagged [dark-energy]

Questions regarding the as-yet-unknown energy permeating the universe that is responsible for its expansion.

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What quantities are being compared in the ratio of dark energy to matterdark matter?

When we say dark energy makes up ~68% of the universe and the rest is dark/ordinary matter (plus light etc.), what quantities are actually being compared? Is it just comparison of total dark energy to ...
jfowkes's user avatar
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3 votes
0 answers
115 views

What are the loopholes in recent claims that dark energy is not necessary?

I read an article on spacechatter about recent work that eliminates the need for dark energy in explaining observations. The pertinent quote from that article is “The study’s findings confirm that ...
tnknepp's user avatar
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0 votes
2 answers
135 views

Light/Dark energy/Dark matter

So I have been working on my comic book project that takes place on another planet. But in my story, there will be warp gates and there will be other civs that can travel between stars. I am ...
Kul Tigin's user avatar
-2 votes
1 answer
204 views

Shouldn't the Friedmann equation take into account the massive extra distance traveled during the time for gravity to travel across the universe? [closed]

I’ve got a question that has been bothering me for the past few years that of the few sources that are only somewhat related to this, none of them say anything about this should be wrong so I can’t ...
Gref's user avatar
  • 21
2 votes
1 answer
63 views

Ejected galaxies, dynamical friction and dark energy?

I have a question after reading this paper (https://arxiv.org/abs/1411.5860). There the authors analyse the ejection of galaxies from their local groups in the presence of dark energy. I had some ...
vengaq's user avatar
  • 937
1 vote
0 answers
69 views

Does dark energy increase eccentricity in orbits of galaxies?

I came across this thesis dissertation which indicates that if a pair of orbiting galaxies are sufficiently far apart (with a sufficiently large orbital radius) then their orbits would change from ...
vengaq's user avatar
  • 937
0 votes
1 answer
49 views

Formula for rate of expansion of the universe vs distance?

How does the distance $r$ scale with the expansion of the universe?For example if $r_{o}$ is the distance between us and a galaxy and $V(r_{o})$ is the rate of expansion of the universe at that ...
Root's user avatar
  • 21
2 votes
1 answer
322 views

If w bosons can create dark matter neutrinos by decay, can they also create dark energy?

Dark energy is often associated with vacuum energy fluctuations. But the experimentally measured Casimir effect suggests that there is almost no vacuum energy.Because most of the vacuum energy is ...
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1 vote
0 answers
36 views

Dark energy affecting the ejection and infall of material in galaxies?

Some galaxies have active outflows of material (mostly gas) that would eventually stop at some distance and then fall again into the galaxy due to gravitational attraction. However, can dark energy ...
vengaq's user avatar
  • 937
7 votes
2 answers
2k views

How long has it been since dark energy started to reverse our slowdown and accelerate the expansion of the universe? 4 billion years ago? 4.5? 5?

Or has it been as long as six billion years? Over the last few years I keep seeing longer and longer numbers... Have researchers noticed something different recently? Or found a mistake in their ...
Kurt Hikes's user avatar
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3 votes
2 answers
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Why can't dark energy be considered a 5th fundamental force?

So I have recently been researching for multiple articles about fundamental forces, currently there are just 4 forces: Gravity Electromagnetism Strong nuclear force Weak nuclear force So far there ...
Alastor's user avatar
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1 vote
1 answer
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ER=EPR and information fuelling cosmic expansion

I apologize in advance for the lack of education, I'm a Canadian hillbilly. I was considering the concepts of ER=EPR and the growth of the black hole's internal system with the addition of information ...
ChristainJP's user avatar
1 vote
0 answers
77 views

Could both the high incidence of supermassive Black Holes (BH) and the expansion of the universe be consequences of vacuum entanglement energy?

The notion that spacetime may emerge from entanglement between factors comprising a Hilbert space decomposition of the vacuum has been suggested by many (for example, M. Van Raamsdonk “Building up ...
RalphW's user avatar
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3 votes
1 answer
330 views

As redshift increases are there more large galaxies from mergers because there was less dark energy in the past?

Dark energy moves galaxies apart.Is this reflected in an increasing number of large galaxies as redshift increases and dark energy decreases?
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0 votes
1 answer
167 views

If black holes contain dark energy would the expansion of the universe be uniform?

Because black holes are different sizes presumably they would contain different quantities of dark energy and so some galaxies would accelerate faster in some directions than others. Dark energy from ...
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1 vote
0 answers
36 views

Modelling dark energy as a potential?

Dark energy is the cosmological constant.However can we model dark energy as some form of field with a corresponding potential?
Volpina's user avatar
  • 111
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0 answers
28 views

Can the cosmological constant be coupled to redshift of radiation

Can space-time be more embedded with the things inside it than we actually think?Can the redshift of radiation be a property of spacetime and that dark energy exists only to conserve the overall ...
appliedSciences's user avatar
0 votes
1 answer
77 views

When dark energy became significant 6 billion years after the Big Bang was there anything else of significance going on in the universe?

I read that a lot of supernovas appeared at this time but were other major events or phenomenon occurring? I ask this in case there could be some physical process helping dark energy to strengthen or ...
user avatar
2 votes
1 answer
149 views

Can the expansion of the universe cool my beer?

So the expansion of the universe stretches the light traveling through the void, as demonstrated by the cosmic microwave background radiation. These photons are lower energy than when they are ...
Yakk - Adam Nevraumont's user avatar
7 votes
4 answers
260 views

What does Dark Energy explain other than the accelerated expansion of the universe?

Dark energy is a vital part of standard cosmology and allows for an explanation of the accelerated expansion of the universe. Does it explain anything else? Or put into other words: If a different ...
Liberty's user avatar
  • 115
1 vote
1 answer
120 views

Coasting universe Hubble parameter behaviour

I’ve recently been trying to wrap my head around the potential behaviours of the Hubble parameter over time for various cosmological models but I’ve run into a little snag when it comes to a coasting ...
Scott's user avatar
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2 votes
1 answer
94 views

Expansion-Collapse cycle in cosmological structures?

Concerning cosmological structures (like galaxies, clusters of galaxies, gas bodies, superclusters...etc) if the elements that make them are close enough they will be attracted towards each other by ...
vengaq's user avatar
  • 937
4 votes
1 answer
105 views

Proportion of dark energy, dark matter, matter

According to the article "Dark Matter" https://en.wikipedia.org/wiki/Dark_matter the current Lambda-CDM model estimates the total mass-energy content of the universe consists of 68.2% dark ...
joh5n's user avatar
  • 41
4 votes
1 answer
157 views

How does the Sachs-Wolfe effect confirm the existence of dark energy?

How is the Sachs–Wolfe effect and the existence of voids significant in providing physical evidence for dark energy?
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4 votes
1 answer
174 views

Could the universe expand forever even if there is no force (e.g., dark energy or eternal inflation) pushing it apart?

Matthew O'Dowd specifically and repeatedly states in the PBS Space Time video called, "Why the Universe Needs Dark Energy", that even without taking an expansionary field into account an ...
Kurt Hikes's user avatar
  • 5,147
2 votes
1 answer
101 views

Will dark energy always repulse observable/dark matter?

We know that the universe is expanding at an increasing accelerated rate, but the ratio of dark energy to observable matter remains constant as dark energy remains constant (please correct me on this)....
Ed_Gravy's user avatar
  • 317
2 votes
1 answer
121 views

Can virtual particles with zero energy and non-zero momentum contribute to dark energy?

I know this is actually a physics question, but I can't ask anything there anymore and the same problem walks on my side on other forums... So, I take my chance to ask it here. A virtual particle is ...
Felicia's user avatar
3 votes
1 answer
137 views

Is the dark matter/baryonic matter ratio the same in galaxies with supermassive black holes?

My hypothesis is that if the ratio of dark matter/matter in galaxies with supermassive(weighing billions of suns) black holes are higher the black hole itself would be made of a large portion of dark ...
SuperFlyGuy's user avatar
4 votes
2 answers
239 views

How can it be justified that every discovery at z > 1 is an indication of "slowing down" or past deceleration?

Type Ia supernovae discoveries at high redshifts (z > 1) support past deceleration (Riess et al. 2001). This past deceleration has also been confirmed using quasars (z ≈ 6) (Risaliti and Lusso 2015)...
Karan R.Takkhi's user avatar
1 vote
0 answers
33 views

Can primordial black holes comprise not only dark matter but also account for dark energy? [duplicate]

Hawking proposed primordial black holes might comprise dark matter. They certainly contribute then to dark energy via their mass and other energies; e.g. gravitational and kinetic. Does this account ...
Lawrence Leach's user avatar
1 vote
3 answers
320 views

Does dark energy make galaxies expand over long periods of time?

Does dark energy expand galaxies slightly over time? I would think this could be verified easily (observe if galaxies far away / further in the past smaller and denser), and might make a good ...
Jonathan's user avatar
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1 vote
0 answers
53 views

Can the Dark Matter / Energy problem be plausibly reframed as an ignorance of gravity problem?

I understand Dark Matter was originally proposed to explain the rotation rate of galaxies. The rate was not explained by observed matter, ergo there must be unobserved matter. An alternate explanation ...
Woody's user avatar
  • 1,040
2 votes
1 answer
450 views

Why would a quantity like the 'Hubble contrast' be squared, then have its square root taken?

From Sabine Hossenfelder's recent video, New Evidence AGAINST Standard Cosmology: And her source.... Figure 2. The variation with increasing void radius of the variance of the Hubble parameter, the ...
Kurt Hikes's user avatar
  • 5,147
1 vote
0 answers
60 views

How much does the Higgs field contribute to the energy of empty space?

The Higgs field was not spontaneously broken when the universe was young and hot (like I am not...:)). At the very high temperature that existed back then, the Higgs' energy of the Higgs field was non-...
Deschele Schilder's user avatar
2 votes
2 answers
113 views

How the data collected during 5 year DESI operation will be analyzed with regards to finding what dark energy really is?

Dark Energy Spectroscopic Instrument, or DESI at the end of it's 5 years operation will create the largest 3-D spectroscopic map of the universe. How the data collected during 5 year DESI operation ...
Alex's user avatar
  • 701
3 votes
1 answer
127 views

Dark Matter Density Parameter Variation

The definition of the dark energy density parameter is $$\Omega_{\Lambda} = \frac{\epsilon_{\Lambda}}{\epsilon_c}$$ where $\epsilon$ is the energy density, $\Lambda$ subscripts represents dark energy ...
wheelix's user avatar
  • 33
-2 votes
2 answers
205 views

Can Quantum tunneling be possible within Blackhole ? And if so, could that be the source of Dark Energy?

Quantum tunneling starts happening when there are empty energy states available for the electrons to occupy and the energy barrier is of the order of the wavefunction of the electrons. Could there be ...
Rajarshi Shukla's user avatar
1 vote
1 answer
223 views

Energy conservation of the universe

I have tried to derive an equation for the total energy of the universe. I have found that, $$E(t)= \delta\dot a(t)^2a(t)\Omega(t)$$ Where $\delta$ is just a positive constant, a(t) is the scale ...
Stan's user avatar
  • 11
0 votes
1 answer
117 views

Are virtual particles the dark energy that curves spacetime negatively?

Dark energy is said to be the cause of the accelerated expansion that all galaxies in the universe seem to have wrt each other. This is said to be caused by an accelerated expansion of space itself, ...
Deschele Schilder's user avatar
3 votes
3 answers
709 views

How is it possible that a universe with mass does not have curvature?

I may know the answer to my question. Mass must curve the universe but the pressure due to energy density may curve the universe in the opposite direction, leading to a flat universe, if they exactly ...
John Hobson's user avatar
2 votes
1 answer
204 views

Demo to get Matter Power Spectrum in cosmology

I would like please to demonstrate the expression of Power spectrum in Cosmology : First, I have the relative contrast: $$\delta_{i}(\vec{x}, z) \equiv \rho_{i}(\vec{x}, z) / \bar{\rho}_{i}(z)-1\quad(...
user avatar
-2 votes
2 answers
152 views

Could blackholes warping space-time create dark energy?

I think the effects of blackholes on the surrounding space is localised to a small area around the blackhole but I wondered if the largest blackholes at the centre of massive clusters could be a ...
Nathan O'Haire's user avatar
5 votes
1 answer
419 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 ...
Natsfan's user avatar
  • 4,494
1 vote
1 answer
140 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 ...
Ritesh Singh's user avatar
-1 votes
1 answer
216 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?
Loop Quantum Gravity's user avatar
3 votes
1 answer
1k 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 ...
macro_controller's user avatar
3 votes
1 answer
102 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 ...
user33808's user avatar
2 votes
0 answers
77 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 ...
radu_cloud's user avatar
5 votes
2 answers
519 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' ...
Mark Besser's user avatar
8 votes
2 answers
796 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 ...
uhoh's user avatar
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