Dark energy Definition and 553 Threads

If you were to concentrate enough of it in one place, could it generate an antigravity field, similar to the hypothetical 'negative matter'? Only it is proven to exist. I am wondering this because it obviously seems to have some kind of repulsive effect that is exactly the opposite of gravity...

Could a "Black Hole" be the cycle of "Dark Matter" powered by "Dar Energy:? Could the "black hole" be like a cycle for "dark matter". So let's say "Dark Energy" is what transports "Dark Matter". So all a black whole is, is a huge amount of energy pulling in "Dark Matter" and pushing it out to...

Hello, I am a general physicist, pursuing it for fun. I work in solar, and the other day while driving up to Sacramento I had a interesting train of thought. From the data we have collected, one interpretation could be that on average, the universe is expanding in every direction at an...

Dark energy = Vacuum energy? I am working on giving a presentation on dark energy and its possible relation to vacuum energy (i.e. one and the same). I have complied information from a couple of books, as well as websites (Scientific American, NASA, Astrophysical Journal). As i understand...

Question regarding dark energy and accelerated expansion. If gravitational force were somehow diminished at large distances----ie lower gravitational constant at huge distances--might this explain the increase or accelerated expansion seen. If this were true, would it be necessary to evoke a...

We currently have a thread about logarithmic corrections to the basic black hole entropy formula. I was thinking about attempts to relate the magnitude of dark energy to the area of the cosmological horizon, and about the various analogies made between the cosmological horizon and the horizons...

Has anyone thought about the big bang and dark energy like this? Dark energy is simply empty space which has the opposite affect of gravity. Put simply, stuff is attractive. No stuff is repulsive. Or, gravity is to mass as repulsion is to empty space. I think that the bigbang had...

I have no formal training in physics beyond the basics, so if my questions make no sense, feel free to ignore them. Dark Matter is described as a gravitational force that either helped form the galaxies or perhaps less likely was drawn in by the formation of galaxies. Personally I prefer the...

I understand that before we knew about dark energy we thought expansion would have slowed down since the big bang but we then discovered the universes expansion rate to be accelerating. My question is, surely if the universe did expand faster at the big bang we would see it expand faster the...

So as someone with no real knowledge of the topic, can anyone tell me what I'm missing? Our observations don't fit our models - we see an accelerating universe, rotation curves which do not meet expectations etc We decide there must be dark matter and dark energy to explain this and then try...

If our regular Energy can spontaneously turn into matter (for instance an electron and a positron pair OR, more rarely two electrons pair) why can't Dark Energy turn into Dark Matter particles? If that's what actually happens then wouldn't the universe eventually decelerate expansion...

A few years ago I came to this forum to ask about the issue of space expansion...and the answer I got then was that the expansion is the nature of the space (or space-time) according to relativity or some other more advanced theory...no one used dark energy to explain the issue at that...

I have been looking into dark matter recently, and I have three questions. When calculating what the gravitational pull of an object should be, do they account only for the mass of that object, or do they account for the total energy of that object? For example, a star will have a lot of mass...

I understand that a Hubble diagram is a graph of recession velocity plotted against distance for distant galaxies, and shows a linear relationship. The Hubble constant is the gradient of the graph. We are now observing extremely distant galaxies with greater than expected velocities due to...

Dear Friends! I have read that in early universe in the inflationary phase the average density of matter was equal to critical density and now it is 10 percent of that due to which it is probably inferred that there must be hidden dark matter. Please correct the information if wrong or...

Hello everyone, this is my first post here, and I hope I'm not asking a too "silly" question. I've already looked here and on the internet, but couldn't find a real answer to it. :) Here's the "silly" question. I was wondering the following, since: - The universe is inflating - The most distant...

Are there any predictions made by the Many-Worlds interpretation of QM that could be ascribed to inflation and or dark energy? In other words, could the hypothetical branching cause our universe to expand?

This paper; http://arxiv.org/abs/1408.6248, Constraints on gravity and dark energy from the pairwise kinematic Sunyaev-Zeldovich effect, proposes an ingenious way to constrain gravity and dark energy models based on ksz effects. They have carefully assessed the potential for errors and biases in...

if the expansion of the universe seems to be accelerating the farther away in distance(and time) we look, then since we're looking into the past because light has a finite speed, and the further you go in the past, the faster the universe's expansion was. why should there be any dark energy...

How can we define SPACE TIME CURVATURE with respect to dark energy and dark matter ?

I'm not a physicist nevertheless I wonder about these things so here goes: On wikipedia I read that the universe contains: 68.3% Dark energy 26.8% Dark matter 4.9% Normal matter But I wonder why normal (light energy) is not mentioned here. Since the beginning of the universe a lot of light...

Why does it make more sense to imagine so much dark energy and dark matter to make things work (cosmologically speaking). Why can't gravity change? It just seems to make a lot more sense to alter one theory, than to start imagining all of this extra none-interacting material, which, oh , btw, is...

Can string theory explain dark matter and dark energy?

Dark Energy is concept of total nuisance to physicist, deriving no crystal-clear concept to stand on. So why are wasting a loads of time and effort on it?

Instead of being a force that works against gravity. Is it possible that dark energy is the pulling of everything towards the event horizon of a black hole? This would marry dark energy with gravity and replace myserious massive amount of energy with a logical source of energy/force that we know...

Ok this may be another stupid Question that I always seem to ask! Does Dark Energy follow the same rule as energy? E=MC^2 or E=MC2?

Ok this might be quite a stupid question but I can't seem to find a clear answer. The Wikipedia page on dark energy says that work done by WMAP and the Planck spacecraft indicate that the universe is made up of about 68% dark energy. But looking at the Wikipedia page titled List of unsolved...

If yes, does dark energy define a frame of absolute rest? In the Einstein field equations, the cosmological constant is just a scalar, so it is independent of frame. But, sometimes, the cosmological constant is described as being a kind of vacuum energy density. Wouldn't a vacuum energy...

I'm not a physics student (chemistry instead), and know extremely little about relativity, so this might be a dumb question and would appreciate simple answers. I'm just curious about this. :) So there is dark matter, which I understand to be the matter that is not detected but needed to...

I have wondered about this for some time: Is dark energy really energy and is work actually being done when it causes the Universe to expand? It seems to me that work is being done in moving all the Galaxies further apart than they were, over coming their gravitational pull. For example a lot...

I read an article that says that inflation at the early stages of the Big Bang explains why the universe is as big as it is today suggesting that if the universe had expanded at the rate it's expanding today it would be no bigger than a full stop. To me this doesn't make sense because I...

First off I claim no expertise in this subject matter, and this is a result of pondering dark energy. When light strikes our eyes(or equipment) how do we perceive its location relative to us? is it just in the exact opposite direction of lights angular impact with the plane whether that is...

Two papers went up today regarding infrared all sky surveys by WISE and 2MASS that affirm the CMB cold spot - http://arxiv.org/abs/1405.1555, A Supervoid Imprinting the Cold Spot in the Cosmic Microwave Background; http://arxiv.org/abs/1405.1566, Detection of a Supervoid Aligned with the Cold...

Could the momentum of light explain the effect known as "dark energy"? I know the distances between galaxies are wast, but so are the surface areas of galaxies, as well as all the stars emitting the light. Would be interesting to see a calculation of the fate of the universe if this was true...

Let's assume that dark energy is uniformly distributed through space (which is one theory) and that dark energy is quantized (as everything else seems to be). We can visualize that dark energy consists of packets of equal size and distance between the packets, so there would be three-dimensional...

Are dark energy and the cosmological constant the same thing?

If dark energy is caused by quantum fluctuations, where does this energy come from? Also according to string theory mass is determined by the sum of a string's positive, vibrational energy and its negative energy from quantum fluctuations. Could it be possible to create a particle with negative...

Hi everyone--first post, thanks for any guidance if I've posted in the wrong place. I've got a simple idea and I'm curious if it's worthwhile doing. How effective would putting a dark surface (perhaps black tiles, or black corrugated plastic) on the bottom of the pool, to warm the water by...

Hello All, In Carroll's there is a brief introduction to a dynamical dark energy in which the equation of motion for slowly rolling scalar field is discussed. Then to give an idea about the mass scale of this field it is compared to the Hubble constant, saying that it has an energy of...

Since first hearing about dark energy in the popular press I’ve always had the impression that we can’t detect it because it’s some exotic kind of energy that doesn’t interact with matter. Is it true that it doesn’t interact with matter or is that just a popular misinterpretation? I mean I...

I have written sci-fi short story. Question is how fast and loose am I playing with science and theories about the big bang and dark energy. This is the summary of assertions in the story. 1) Dark energy is the reason for the original expansion of the observable universe including (space and...

From what I have gathered, dark matter is finite, correct? The more space expands, the less dense dark matter will be. So billions or trillions of years from today, space will have expanded a lot and the density of dark matter will decrease from a universal view. But if dark energy is a constant...

I found an interesting paper... Dark Energy and Dark Matter as Inertial Effects A globally rotating model of the universe is postulated. It is shown that dark energy and dark matter are cosmic inertial effects resulting from such a cosmic rotation, corresponding to centrifugal and a...

I'm interested in the ultimate fate of the universe. And it seems that the most prevalent theory is the Big Freeze. From what I can gather the BF is caused by dark energy making the universe expand to the point that stars can no longer form, resulting in cold dark space filling the universe...

I’ve read a bunch of post about how the universe does not exist inside, nor is, a black-hole. Still, for my question I would like to assume the universe exists within an event horizon (actually highly curved space-time, that locally, appears flat), and has a massive singularity at the...

Sorry in advance for this probably stupid question. If there is entanglement is there not entaglement for all particles. If so, could there not be entanglement for the Higgs boson, and therefore our own gravity, could have an equal and opposite force, both combining for a net effect of...

Hello! This is my first post, so go easy on me! I'm working through Scott Dodelson's book Modern Cosmology http://books.google.com/books?id=3oPRxdXJexcC&pg=PA23&source=gbs_toc_r&cad=4#v=onepage&q&f=false and I am a bit confused about equation 2.85: $$\rho_{DE} \propto e^{-3 \int^a...

Sorry to have such a broad subject line but I was in a contimplative mood yesterday and the mind was wondering and pondering… From the publication of Sir Isaac Newton,”Philosophiæ Naturalis Principia Mathematica”, the science world has been challenging the findings around gravity proposing...

Dark Energy is said to be present in order to drive the observed acceleration of the expansion of the universe and Dark Matter is hypothesised to be present to drive observed gravitational effects. Would a large mass of dark matter distributed around the outer parts of the universe have the...

What are the current theories as to the source of the new space that accounts for dark energy?