Dark Matter and Dark Energy… the Same Thing?
Written by Fraser Cain
I've said it many times, but it bears repeating: regular matter only accounts for 4% of the Universe. The other 96% - dark matter and dark energy - is a total mystery. Wouldn't it be convenient if we could find a single explanation for both? Astronomers from the University of St. Andrews are ready to decrease the mysteries down to one.
Dr. HongSheng Zhao at the University of St. Andrews School of Physics and Astronomy has developed a model that shows how dark energy and dark matter are more closely linked than previously thought.
Dr Zhao points out, "Both dark matter and dark energy could be two faces of the same coin. "As astronomers gain understanding of the subtle effects of dark energy in galaxies in the future, we will solve the mystery of astronomical dark matter at the same time."
Just a quick explainer. Dark energy was discovered in the late 1990s during a survey of distant supernova. Instead of finding evidence that the mutual gravity of all the objects in the Universe is slowing down its expansion, researchers discovered that its expansion is actually accellerating.
Dark matter was first theorized back in 1933 by Swiss astronomer Fritz Zwicky. He noted that galaxies shouldn't be able to hold themselves together with just the regular matter we can see. There must be some additional, invisible matter surrounding the regular matter that provides the additional gravitational force to hold everything together.
And since their discoveries plenty of additional evidence for both dark energy and dark matter have been seen across the Universe.
In Dr. Zhao's model, dark energy and dark matter the same thing that he calls a "dark fluid". On the scale of galaxies, this fluid behaves like matter, providing a gravitational force. And in the large scales, the fluid helps drive the expansion of the Universe.
Dr. Zhao's model is detailed enough to produce the same 3:1 ratio of dark energy to dark matter measured by cosmologists.
Of course, any theory like this only gains ground when it starts making predictions that can be tested through observation. Dr. Zhao expects the work at the Large Hadron Collider to be fruitless. If he's right, dark matter particles will have such low energy that the collider won't be able to generate them.
The paper was recently published in the Astrophysical Journal Letters in December 2007, and Physics Review D. 2007.
Original Source: University of St. Andrews News Release
Filed under: Cosmology, Dark Energy, Dark Matter
February 6th, 2008 at 2:18 pm
Let's see now. There's got to be 'dark energy' and 'dark matter' because our theories say so. And of course our theories have always proven out to be correct. No other explanation apparently. Now if we could just do more than discover it, like maybe, actually find out what it is. Personaly, I'd be embarassed to have a 'theory' wherein 90% of the stuff is actually unknown. Oh well, back to our GUT theories. Maybe that new grant will come through!
February 6th, 2008 at 2:20 pm
Can we create the stuff?
Does it already exist around us, and if it does, can we measure it?
February 6th, 2008 at 2:37 pm
E=mc^2 works, so why not ED=md^2 ? my point being if there is a known relationship where matter and energy are known to be the same, then same is true for dark energy and dark matter. And for all those who still believe in the big bang, your are idiots. the universe is going through phase shift just like an atom does when it gains or loses energy, from say a neaby universe.
February 6th, 2008 at 3:42 pm
I still believe in the Big Bang so I guess I'm an idiot.
February 6th, 2008 at 3:44 pm
Geez, here we go again. Another picture of some PhD standing at a blackboard… Put down the chalk and get back to real work. Even stop to think that the 'dark' stuff you're looking for may actually be one of those extra-dimensions you physicists seem to have proven exist — we never know what it is but can only infer its existence by its effect on our universe. Oh how I love writing physics-babble…
February 6th, 2008 at 3:52 pm
How i love to watch people attack physics–the most provable and disprovable science around. But I'm an idiot for believing the Universe began from a single point called the Big Bang. So let me know the real truth, you physics haters.
February 6th, 2008 at 4:15 pm
[...] Fuente: Universe Today [...]
February 6th, 2008 at 7:00 pm
I agree with Chris. If regular energy and mass are interchangeable why couldn't the dark stuff do the same
February 6th, 2008 at 7:15 pm
It seems to me that people who agree with someone else, are agreeing with themselves using different names…at least sometimes.
February 6th, 2008 at 7:22 pm
I agree with idiot. DOH!
February 6th, 2008 at 7:47 pm
"But I'm an idiot for believing the Universe began from a single point called the Big Bang."
The Big Bang Theory, as I understand, its not an attempt to explain the origin of the universe. The Big Bang was not an explosion. It just states that the universe has been expanding from a super hot, super dense state ~13 billion years ago.
It is simply, the apparent expansion of the universe.
Saying "we came from the big bang" is therefore, in a sense, like saying "life on earth came from natural selection."
It just bugs me when people talk about the big bang theory or the theory of natural selection in the context of origins (of the universe/life, respectably).
February 6th, 2008 at 7:51 pm
Why is it that the internet is FILLED with people leaving passive/aggressive, smug, smart (bleeped) comments instead of constructive critisism, let alone anything insightful and/or intelligent?!? This covers the gamut from science sites such as this, to political, economic, computer gaming, et al…
February 6th, 2008 at 8:05 pm
I didn't think I was being rude, I was just making a point.
Feel free to correct me. I consider that constructive.
But about the article, it is an interesting thought. I'd like to read more about this "fluid" and how it drives expansion on the largest scales but acts as a "pull" on galactic scales. Very counterintuitive.
But isn't it always?
February 6th, 2008 at 9:01 pm
Maybe this dark stuff is a force that is kind of like antimatter and so it would accelerate things such as matter. just as matter causes friction and slows things down (decceleate), this stuff would speed things up (accelerate) things.This could also explain wormholes.
February 6th, 2008 at 10:16 pm
I'm trying to understand this as best as possible, being only in high school, but if it was antimatter and actually had the ability to lessen the friction between matter, how would it hold things together? Or does antimatter have a gravitational pull all it's own? From what I gather from the article, this dark matter is something that can hold a galaxy together. I can see from your standpoint how it would accelerate the expansion of the universe, but I still don't see how it would affect a galaxy. Wouldn't the galaxy disperse if it was accelerating as fast as the universe?
February 6th, 2008 at 11:47 pm
Dwight, I like your point about the dark energy/matter actually being the higher dimensions. I've been thinking about that myself, I think we are just too small to observe them but yet all matter and energy that we see is nestled in this, whatever the stuff is!
I wonder if there is research out there on this.
February 7th, 2008 at 1:03 am
I think the suggestings made by of N. Stone are interesting concepts. Didn't Einstein theorize the existence of something in his ToR beyond gravitional relationships of mass on mass?
February 7th, 2008 at 2:46 am
Cosmology is a far cry from physics with regards to certainty. Of course the nature quantam mechanics still gives classical physicists headaches. Any physicist would cringe at a scientific discipline that has to invoke entities such as dark matter and dark energy to keep its theories from sinking. These concepts still seem a bit far fetched to me and I, like many others, would like to see either of these detected and measured for the first time before I am satisfied that everyone is on the right track. A little bit of reserved judgement and skepticism is always healthy. I always find it amusing how cosmologists can become absolutist when someone questions the existance of these entities which have yet to be independently observed and measured. To such people I ask is this a religion or a scientific dicipline?
February 7th, 2008 at 2:48 am
[...] Dark Matter and Dark Energy… the Same Thing? I've said it many times, but it bears repeating: regular matter only accounts for 4% of the Universe. The other 96% - dark matter and dark energy - is a total mystery. Wouldn't it be convenient if we could find a single explanation for both? Astronomers from the University of St. Andrews are ready to decrease the mysteries down to one. Click to continue… [...]
February 7th, 2008 at 3:24 am
We searched for and rejected the idea that there is a fabric or medium, call it the aether, over a century ago.
Let's start by dismissing the term particle as too specific to human sensory perception and instead call the collective observed phenonena - masses - instead just behaviors or functions.
Dark whatevers (mass and or energy) becomes the framework within which the observable functions operate.
Like the layers of abstraction that build up from machine language in a computer (read here dark whatevers or the medium) the observable behaviors of masss (e.g. inertial and weights) , etc. and energy become application layers on top f an operating system.
Gosh, aether is back!
February 7th, 2008 at 4:50 am
Unfortunately, much of the "I'm right and the rest of you are idiots" stuff comes from intuitive thinking.
It has long been known that intuition can be thoroughly misleading in physics - especially on very small or very large scales. Let's all keep open minds on this. There's a lot we don't understand, and it could be some time until we do (if ever).
February 7th, 2008 at 6:33 am
I think i would have to say the some of you actually have valid points, Dwight, yes i can agree with you that this stuff might just be another higher dimension but what is it growing from?
My best guesstimate would be from everything that the black holes in our universe are eating up. I mean it has to be going somewhere right? And when this alternate universe fills up with too much matter then POOF another universe is so called born from our point of reality.
February 7th, 2008 at 8:42 am
All I was meaning is that if the universe is expanding (which it is) and at an accelerating pace (whch it is), that is similar to what happens in an atom during phase shift. the electrons increase orbit to take on energy or decrease orbit and expel a photon. i believe the universe is one of many and ours is taking on energy from a neaby universes. i dont see why an expanding universe leads people to only one conclusion that it started from one spot. we can observer at the atomic level the same thing the universe is doing, but do atoms originate from one spot? make sense? i could be wrong, but i believe that in my heart.
February 7th, 2008 at 9:15 am
Dr. Bill,
You got it right!!
Why does anyone assume that with their limited knowledge and understanding that they should be able to comprehend the greatest mysteries of the universe? Not even the scientists working on this think they know how it works. There are some working theories and suggestions only. If anyone here thinks that they can actually understand alternate universes as put forward by string theory, then you live in a overwhelmingly simplified universe or you are kidding yourself. They are, at best, mathematical concepts without even a hint of what they might mean to us in a visual or Newtonian physics way. We are babes in the woods in this field.
February 7th, 2008 at 10:36 am
In response to Cloy: don't think of antimatter, but of a new kind of vector field, like the magnetic field fridge magnets create. (A vector is an arrow, so a map of wind speeds and directions is another example of a vector field.) Dr. Zhao seems to be saying that he can mathematically define a vector field that has positive pressure (and thus positive gravity) in and near galaxies, but negative pressure (which accelerates the universe) in regions far away from galaxies. The difference between those regions is the acceleration of gravity - relatively high near galaxies, relatively low far from galaxies - and at a certain acceleration his `dark fluid' changes its behavior. It predicts 2.25 times more 'dark energy' than 'dark matter', not far from the factor of 3 observed; that plus some other predictions make it more than just a mathematical curiosity. We'll see if it holds up to testing…
February 7th, 2008 at 11:34 am
There appears to be much confusion, even amongst many science and math teachers, about the so called 'Big Bang'. The 'Big Bang' is not a theory! It is a description on the present behavior of the universe that arises as a consequence of Einsteins 'General Theory of Relativity', and supported by many astronomical observations.. It does not concern itself with the beginning of the universe: it predicts an absurdity - a singularity - at some point in the distant past. This is a long recognized constraint on the description, and possibly on the theory: hence attempts to overcome this problem by formulating 'Cyclical' universe hypothesis, 'string' and 'M' theory, etc.
As to the topic of this article, the possible unification of dark energy and dark matter is intriguing but I am still uncomfortable with these mysterious 'dark matters'. Dark energy may seem to be necessary because of oversimplifying our models of the universe: It reminds me of the story of the physicist asked by a dairy scientist to help him improve the milk yield of his herd. The physicist began "we will assume and spherical, isotropic, and homogeneous cow",
Other explanations for the observed phenomena are not, at present, in fashion but seem to me to be worth much more consideration. For example; The paper by Nan Li, Marina Seikel and Dominik J. Schwarz (arXiv:0801.3420v1 [astro-ph] 22 Jan 2008). "As to the problem of dark energy and dark matter, their unification: Is dark energy an effect of averaging?" In place of assuming that unknown dark matter and dark energy are the dominant contributions to the cosmic energy budget. They review the logic that leads to the postulated dark energy and present an alternative point of view, by properly taking into account the influence of cosmic structures on global observables.
Mustapha Ishak, James Richardson, Delilah Whittington, David Garred (arXiv:0708.2943v1 [astro-ph] 22 Aug 2007) "Dark Energy or Apparent Acceleration Due to a Relativistic Cosmological Model More Complex than FLRW?". Their work appears to support the possibility of apparent rather than real acceleration.
And David L. Wiltshire has taken an alternative approach to this problem for many years. For example in "VIABLE INHOMOGENEOUS MODEL UNIVERSE WITHOUT DARK ENERGY FROM PRIMORDIAL INFLATION" (Xiv:gr-qc/0503099v5 11 Jul 2005)where, from his abstract "A new model of the observed universe, using solutions to the full Einstein equations, is developed from the hypothesis that our observable universe is an under dense bubble, with an internally inhomogeneous fractal bubble distribution of bound matter systems, in a spatially flat bulk universe…."
Perhaps it is time to begin to question the very existence of dark matter!
February 7th, 2008 at 4:03 pm
If Big Bang existed , so where was is come from ? . If there were extra dimesions , then who made them . Don't tell me that is God , and don't tell me it works itseft . Nothing in this universe has no its reason , even God .
To the article , I think Dr Zhao's point is right and the explanation of Chris Paino is reasonable .
February 7th, 2008 at 5:55 pm
Ok, so I sorta get it.
Though I do have a couple questions.
How far apart are galaxies usually? and what lies in between them? Floating stars or something? It does make it hard to believe that there isn't anything in-between galaxies besides dark matter. And I hear researchers trying to figure out what lies beyond the universe's boundaries, but not a single one trying to figure out what lies in the center. In a galaxy it's easy to see the center of it is either billions of stars or one massive one (whichever it is, is hard to tell when just looking at a picture of one) but is the center of the universe the same? One massive collection of stars/gravity/dark matter? It's all very confusing.
February 7th, 2008 at 5:58 pm
Thanks Phan An. Assuming accelerated expansion means only one conclusion, that things started in the middle, we dont have enough informationt o draw that conclusion. another analogy would be if someone had a train going toward them and they opened their eyes for 1 millisecond and closed them, during that 1 millisecond observation, they would not even realize the train was moving. the observation period is too short. as we observe the universe, its from the perspective that it must be expanding from some beginning location in the middle. if we observe it long enough, it may start to contract back for all we know. thats what i think is going on. thanks for thinking it's plausible that we don't know something we think we do. (big bang).
February 7th, 2008 at 6:03 pm
It just seems that what happens at atomic level is similar to solar system level and galaxy level and universe level. for my whole life, i thought there has to be stuff in middle of galaxy because there was stuff in middle of atoms. science didn't teach that when i was in shcool, it just seemed to make sense. Then, they find out middle of galaxy has large black hole. I wasn't surprised to hear that. I wont be surprised when they find the middle of the universe has something in it. Perhaps we can't see it, but something's got to be holding the universe together. In any event, i just see things as repeating pattern..atom, solar syste, galaxy, universe(s).
February 7th, 2008 at 6:42 pm
I am reminded of the deaths of stars…the outer layers being repulsed by the collapse of the core.
It's hard to visualize how something could simultaneously expand and contract (oversimplified? well of course), but thats too be expected. Our brains are much better at comprehending the accumulated effects than all the variable causes (which tend to get lost or meaningless in the grander scope of things, e.g. chaos theory).
I like it when ideas like this set up camp in my thoughts and won't be ignored.
February 7th, 2008 at 7:54 pm
hmm. I see what Chris Paino is saying (about patterns of atoms/solar systems/galaxies/etc.) but now I'm wondering why the middle of the galaxy glows brightly like it does. Almost like a star in itself. If this is, as you say, a black hole, why doesn't it seem like one that is smaller and already in the galaxy it's creating? I heard black holes were just dark spaces with immense amount of gravity (could this contribute to dark matter?) so why is the center of a galaxy look more like a giant star? Furthermore if the relation between atoms, solar systems, galaxies, and universe(s?) exist then if the universe is expanding, then why doesn't the galaxies, solar systems and atoms expand too? or do they at a lower rate of speed? sorry for all the questions, but they're really bugging me.
February 7th, 2008 at 9:41 pm
> How far apart are galaxies usually?
Big galaxies are about 5 million light years apart on avg.
> and what lies in between them? Floating stars?
Mostly just ionized hydrogen and helium gas, plus dark matter (most astronomers think).
> And I hear researchers trying to figure out what lies
> beyond the universe's boundaries, but not a single one
> trying to figure out what lies in the center.
That's because the universe has no center. It's easy to understand if you imagine a universe of two space dimensions (instead of three) plus one time dimension. The two-dimensional universe is curved like a balloon - but remember, you can only move in two dimensions - on its surface. The third dimension (the "radius" of the balloon) is time - so the balloon-universe expands in time, not in space: it had a higher (surface) density in the past, but it never had an edge or a center in space, just a beginning in time - the Big Bang. Now, it's harder to picture the same thing in 3 space dimensions + 1 time dimension, but that's roughly what Our Weird Universe (as I like to call it) is like.
February 7th, 2008 at 9:54 pm
You lost me.
February 8th, 2008 at 12:26 pm
> You lost me.
No problem - it takes some getting used to!
Try this: in which direction - North, East, South or West - would you drive a car to get to the center of the Earth? Well, you can't drive in any of those directions and reach the Earth's center; you need to move in a 3rd space dimension.
And no matter what direction in space you move in our universe, you'll never reach a 'center'.
So, instead of the Earth's surface (a 2-dimensional surface plus a 3rd dimension of space), imagine a balloon where the 3rd dimension is time. Then you have a 2-dimensional universe expanding in time. The "center" of that balloon universe is a point in time - the Big Bang. The balloon universe, like ours, has no beginning or end in space, just a beginning in time.
Sounds weird, I know, but the difference between that balloon universe and our 3-D universe expanding in time is just slightly different math.
There's another description of all this here:
http://www.ucolick.org/~mountain/AAA/030209.html#expansion
February 8th, 2008 at 4:05 pm
salineman,
I take no offense at your remarks. In fact, I seem to agree. The reason I use pen names like "idiot" and "not as smart" is my inability to articulate as well as most folks on here. If I understand you, the Big Bang wasn't really an explosion, but a sudden flux and expansion of which we know nothing of what came just before it.
That's a great mystery–the "what caused the Big Bang?" Anyone Know?
February 8th, 2008 at 8:35 pm
So if we were able to find a way to use this "3rd dimension" in the universe, would that be sorta like "time-travel"?
It's hard to picture something like time being able to fill the space inside the universe if the universe was like a balloon because that makes time seem like a form of matter that is pushing against the sides of the universe, making it expand.
It certainly would be weird and awesome (the archaic form of the word) to be floating inside that if ever we found a way to.
Also, if a point inside the "balloon universe" is a point in time, would it be recorded like a fossil in a rockbed? If that's the case wouldn't we look at the universe like (shrek reference coming) an onion?
February 8th, 2008 at 8:36 pm
It wasn't a Big Bang, it was actually a Big Tug caused by the Gravitational Force provided by the Dark Matter that existed in the surrounding "Pre-Universe" back then. That Dark Matter is the same DM we now believe exist. I postulate the Universe existed prior to the "Big Tug" but in a totally different form. Not enough room here for the whole theory.
February 8th, 2008 at 10:51 pm
And I call myself idiot. ha ha ha!
February 8th, 2008 at 10:53 pm
just joking. i know you're joking.
February 11th, 2008 at 4:31 pm
You know, Newton discovered this inverse square Law, based on a simple algebraic equation. He used math to explain his Law, and math is a theory, The Theory of Numbers… Hmmm, this is getting interesting. Maybe there is some Imaginary Universe, like, U i = (U(-1)). Hey, maybe Universe has a trigonometric identity that makes it seem different, but it is actually the same thing. What if the Universe is a Sum of Riemman (or Riemann, wathever) of an infinite amouth of Universes, and so, of matter, wich, by the way, implies that matter could be created or destroyed…. Oh, what da' I completely lost it, HAHAHA! I'm saying that classic Physics is wrong because its laws are based and explained by a theory. Man I'm not making sense at all…right???
Sorry to poke your Einstein for a dull moment.
February 11th, 2008 at 4:32 pm
Sorry for the misspelling. AMOUNT it should say.
February 12th, 2008 at 12:07 pm
[...] I read an article called "Dark Matter and Dark Energy…the Same Thing" that was written by Fraser Cain. In that article they talked about regular matter only [...]
February 12th, 2008 at 7:23 pm
Seems to me that super string theory provides an approachable explanation as it posits the existence of all things, matter, energy, particles, waves and space/ time itself as manifestations of variations in string vibrations. If this line of reasoning is followed, it becomes possible to reconcile what appears to be contradictory into a unified description of "how stuff works" and what stuff is. It still leaves open the ultimate question of the origin of any and all of it. However, it is likely that the end of all inquiry will be but to arrive at the place whence it began.
February 26th, 2008 at 3:58 pm
If the Big Bang really was, then before it happened, it must have been the biggest-baddest black hole ever. And if it was indeed a big black hole, then why did it destabilize and explode, or eject all of its contents? Is this 'ejection' finished? The contents and distribution of the universe suggests that this 'ejection' is 'still' going on, depending on the time scale due to light speed. Does this indicate/suggest that black holes (as we currently know them — they suck and do not spit) can explode or eject matter? And if they do explode or eject, is the result of this the start of a galaxy?
February 27th, 2008 at 11:02 pm
I asked sorta the same thing a couple weeks ago, John. Apparently we (myself included) say that the universe was started, not in space, but in a certain time.
This is from what I understand.
Think of the universe like a balloon. The "air" inside and around this balloon isn't a place in space, but a place in time (the inside being the past and the outside being the future). When the balloon started swelling, that was the beginning of time. But as you know, balloons are hollow and the elastic isn't found in the exact center of the balloon. All that's inside it is air, or in this case, time. If your black hole, or an explosion existed to begin with, is not really likely unless the explosion expanded like a balloon.
To answer your galaxy question, a supernova is what you're thinking of. The intense explosion/implosion of a superstar scatters matter all around the universe, but due to the immense energy/gravity of the implosion, it then creates a black hole. Since the matter surrounding the black hole is traveling at an incredible velocity, it somewhat gets caught by the gravity and fights to be freed. Thus you get rotation and the birth of a galaxy. I understand that might not be quite the whole process, but thats the gist of it i guess. Someone correct me if i'm wrong.
February 29th, 2008 at 3:36 am
Dr. Murad Shibli with the Aamerican University of Sharjah has proposed a new theory on dark energy and has been publihsed at IEEE and entitled as "The Foundation of the Theory of Dark Energy: Einsteinapos;s Cosmological Constant, Universe Mass-Energy Densities, Expansion of the Universe, a New Formulation of Newtonian Keplerapos;s Laws and the Ultimate Fate of the Universe". For more information please visit the following link.
February 29th, 2008 at 3:44 am
Dr. Murad Shibli at the American University of Sharjah has proposed a new unified model on dark energy and dark matter. This model will b epresented at INTERNATIONAL CONFERENCE ON RENEWABLE ENERGIES AND POWER (ICREPQ 08 ) in Spain on March 12-14, 2008. The article presents a proposed equation of state of dark energy and dark matter as one unified entity. Such an equation is derived based on the assumption that dark
energy and dark matter behave as a perfect fluid, the ideal gas equation, Boltzmann constant and the energy-mass
principle of Einstein. As a result of that, it is found that dark energy and dark matter are not distinct, on the contrary, both dark energy and dark matter represent one
unified entity. This agrees with the recent observations of NASA that dark energy and dark matter has close density values and in the range of 10^-26 kg/ m^3. The ratio between the energy density (in Joules) and the mass density (in kg/ m^3) are proportional to the Square of the Speed of
light. Moreover, this ratio is found to be equal to the product of the space temperature and the dark energydark matter parameter (as a perfect fluid). An alternative presentation shows that the ratio between the dark energy
and dark matter molecular density is proportional to Boltzmann constant. Furthermore, this approach might be
useful to utilize the free source of energy associated with dark energy and dark matter at high temperatures. Finally, simulation for our milky way shows the validity of these results
February 29th, 2008 at 9:20 am
I believe that the smallest possible space "particles" are actually the bosons of the gravitational field. It would explain many divergent theories. Space "particles" overlapping under mass\energy density would explain space-time curvature, it would give a mechanism for gravitational waves and would unify general relativity with quantum mechanics. It's really neat.
March 1st, 2008 at 6:08 pm
If dark matter really existed, the amount of dark matter mass necessary to cause the observed irregularities would logically preclude the rapid expansion of the Universe that we now have. Furthermore, I cannot conceive of such a mass that would not have pulled itself together forming very large bodies. May I suggest that our observed irregularities could be "Space Time Warp Proportional Factor"; depending upon how close a body is to the center of the Galaxy? Gerald Blancett
April 19th, 2008 at 2:32 am
Hi Frend
http://www.hypothesis-of-universe.com/en/index.php?nav=home