One of the biggest questions that occupy particle physicists and cosmologists alike is: what is dark matter? We know that a tiny fraction of the mass of the universe is the visible stuff we can see, but 23% of the Universe is made from stuff that we cannot see. The remaining mass is held in something called dark energy. But going back to the dark matter question, cosmologists believe their observations indicate the presence of darkmatter, and particle physicists believe the bulk of this matter could be held in quantum particles. This trail leads to the Large Hadron Collider (LHC) where the very small meets the very big, hopefully explaining what particles could be generated after harnessing the huge energies possible with the LHC…
The excitement is growing for the grand switch-on of the LHC later this summer. We’ve been following all the news releases, research possibilities and some of the more “out there” theories as to what the LHC is likely to discover, but my favourite bits of LHC news include the possibility of peering into other dimensions, creating wormholes, generating “unparticles” and micro-black holes. These articles are pretty extreme possibilities for the LHC, I suspect the daily running of the huge particle accelerator will be a little more mundane (although “mundane” in accelerator physics will still be pretty damn exciting!).
David Toback, professor at Texas A&M University in College Station, is very optimistic as to what discoveries the LHC will uncover. Toback and his team have written a model that uses data from the LHC to predict the quantity of dark matter left over after the Big Bang. After all, the collisions inside the LHC will momentarily recreate some of the conditions at the time of the birth of our Universe. If the Universe created dark matter over 14 billion years ago, then perhaps the LHC can do the same.
Should Toback’s team be correct in that the LHC can create dark matter, there will be valuable implications for both particle physics and cosmology. What’s more, quantum physicists will be a step closer to proving the validity of the supersymmetry model.
“If our results are correct we now know much better where to look for this dark matter particle at the LHC. We’ve used precision data from astronomy to calculate what it would look like at the LHC, and how quickly we should be able to discover and measure it. If we get the same answer, that would give us enormous confidence that the supersymmetry model is correct. If nature shows this, it would be remarkable.” – David Toback
So the hunt is on for dark matter production in the LHC… but what will we be looking for? After all dark matter is predicted to be non-interacting and, well, dark. The supersymmetry model predicts a possible dark matter particle called the neutralino. It is supposed to be a heavy, stable particle and should there be a way of detecting it, there could be the opportunity for Toback’s group to probe the nature of the neutralino not only in the detection chamber of the LHC, but the nature of the neutralino in the Universe.
“If this works out, we could do real, honest to goodness cosmology at the LHC. And we’d be able to use cosmology to make particle physics predictions.” – Toback
Source: Physorg.com
Hi Kevin,
You might find one of Fraser’s articles of interest: http://www.universetoday.com/2008/02/06/dark-matter-and-dark-energy-the-same-thing/ – it explains how dark energy and dark matter fit in with our picture of the Universe. Although Dr. Zhao doesn’t think the LHC could create dark matter…
Hope that helps 🙂
Ian
Wikipedia is very useful, especially when it gives links to specialist sites that deal with the subject under discussion. So is http://antwrp.gsfc.nasa.gov/apod/archivepix.html, whose links to astronomical and cosmological Web articles and sites yield treasures. The problem with Wikipedia is that many articles on it are not properly referenced, don’t cite sources, have abberrant or dead wrong material in them, or are otherwise badly flawed. Those articles that give bibliographical links that do check out, cite their sources, which prove to be relevant to the discussion at hand, and give information that proves to be accurate are worth referencing here or anywhere else. Those who do reference such articles, of course, should make sure that, insofar as is possible, that the Wikipedia articles thus referenced are relevant to the discussion and check out well.
A few more months and we’ll all get sucked into a black hole. sweet
We know that a tiny fraction of the mass of the universe is the visible stuff we can see, but 23% of the Universe is made from stuff that we cannot see.
How did that get figured out? I’m not saying it’s not true, but it’s just tossed around so much I’ve never heard how this conclusion was arrived at. It’s all “Dark matter! Dark matter! where’s the dark matter” but always just “scientists know that we only see a small fraction of the mass in the universe…” but never how they know.
Kevin F. Says:
July 9th, 2008 at 6:19 pm
It’s a good question Kevin. In broadest possible terms, we can quantify how much matter we can see in the universe by using the apparent luminosities of various objects we see through the telescope in surveys etc. and, through a series of calculations, work out the mass of what we can see.
But then, when we observe certain features of the universe such as the rotation rate of galaxies, the orbital motion of galaxies in clusters and much more, the stuff that we can see is not nearly enough to exert the gravitational force required to make these objects behave in the manner in which they do. Something that we cannot see is exerting this gravitational force – Dark Matter! Furthermore, we can work out that the distribution of this DM doesn’t mach the distribution of visible matter, so there is good reason to think that Dark Matter possesses it’s own unique properties. Could it just be very dimly lit normal matter? There are a number of good reasons to think that it is not, which I won’t go into here.
So when we calculate how much ‘dark matter’ would be required to exert the gravitational force that makes objects that we observe behave as they do, we arrive at a certain percentage dark matter, and a certain percentage ‘normal’ matter.
Fair enough, but the situation is complicated by so called ‘dark energy’. What is this? Well, we take our standard Big Bang model. The universe explodes into being, ‘inflation’ works it’s magic for a time and then dies out, and the universe is set expanding. Three things were formerly thought possible to happen after this – The first is that the universe would expand for ever, if it was expanding past the ‘escape velocity’ of itself, but due to the gravity of all else in the universe, would slow down gradually. The second is that the mutual gravitation of the universe would eventually halt the expansion, and cause everything to come crashing back in on itself. The third is that the universe would have just enough velocity to overcome its own gravity, but slow almost to a stop – just inching forwards over the eons in the end. Unfortunately, nature had other ideas, and certain observations of distant objects – supernovae – have shown fairly conclusively that the universe’s expansion is accelerating! This is an astounding claim, as the only force that we know of that acts over a long range is the gravitational force, which is exclusively attractive – the universe should be slowing down, not speeding up!
So getting to the crux of it all, we can calculate the rate at which the expansion is speeding up, and the contribution to self-gravity from all of the objects in the universe – dark matter and normal matter combined, and then it is a simple matter to work out the energy that would be required to oppose this gravity and drive an accelerating expansion.
Now, as we have E=mc2, Einstein’s famous diddy, we can think of mass and energy as one and the same. So we know how much matter we have, how much dark matter we have, and how much dark energy we have! And we can then present that data in a nice neat little pie-chart that is unequivocally correct. Maybe.
In reality, it is nowhere near this simple – there are a lot of ifs, buts, maybes and complex calculations involved. But it is our best attempt so far, so we run with it until science eventually shows us the (almost certain) errors of our ways.
Anyway, that was a fairly poor introduction to the subject – I’m sure you could find loads of stuff on Wikipedia and many books online and in a bookshop that would crap all over my effort. So now, it’s back to work for me…
Yay Astrofiend! No quoted reference to Wiki! 🙂
Just to expand on the topic of universal expansion…it always blows by mind to think that the space itself is expanding. It would be easier to believe that the universe is finite and that it is expanding into nothing, but that just doesn’t seem to be the case according to WMAP measurements of the cosmic background radiation.
I’ve also read some articles that say that the distribution of dark matter is inferred through gravitational lensing effects, and after a computation of this lensing effect, the dark matter distribution looks like filaments that connect the cosmos, like a giant spider web.
Does this ead to quarks and duarks?
Man, i have been waiting for this for quite some time now….. who ever is there at the LHC, can’t they just flip the “on” switch? Or is it really big? All kidding aside, the problem with “dark” matter and “dark” energy is that if it doesn’t “interact” with anything, than how can we ever, ever, ever detect it? oh wait, it DOES interact, by having gravitational effects…. well than, if we could harness dark matter would we be able to play with gravity? Such as with space ship propulsion? If we could create a mass of dark matter in front of a ship, the gravity would be able to pull it along! How about that! Well i guess we have to first prove it exists before we can start trying to harness it……
I find this quite contradictory, if no one knows what is dark matter how can they say that the LHC will be able to recreate it?
Nonethless, I’m quite curious to read about the experiment results.
“All kidding aside, the problem with “dark” matter and “dark” energy is that if it doesn’t “interact” with anything, than how can we ever, ever, ever detect it?”
This will, if att all, quite similar to how the neutrino was discovered. It ran away with energy and changed the (apparent) lepton number. The neutrino was inferred and taken for granted some years before it was actually detected. If there is a heavy particle created that we don’t directly see, we will always be able to detect the missing energy/momentum (and perhaps a violation of some symmetry) that is needed to create this particle.
“Should Toback’s team be correct in that the LHC can create dark matter, there will be valuable implications for both particle physics and cosmology”.
That has to be the understatement of the year!
Otherwise, if,if,if… or how to make Texas hay, sensation and a press release out of nothing.
Oh please, you have no idea of what it “could” create. Stop making up fantastic stories and go do some real work. Personally, I hope it makes cheap gasoline!
A lot of what has been said has been very intriguing, although I have yet to see anyone mention a complete possibility. I offer an insight that has not been refuted to my knowledge.
Take, c = the past, b = the present and a = the future, then time, as we perceive it goes in the direction of c, b, a. Time as we all know, has been around before us and when we got here our ancestors, up to us, have always perceived time as c, b, a. I submit that the fourth dimension (time), is the catalyst. An example of this would be when you are sitting in your car in the center lane and there are two cars on either side of you. The two cars on either side of your car move slowly and simultaneously backwards, you will perceive it as if you were moving forward, even though you are sitting still. Suppose time’s natural motion is to move through space as a, b, c, (in our perspective, reverse). This could get a little complicated, being that this would mean that we all know what is going to happen after the present, (our past) but we would not know what is going to happen before our present, (our future). Gravity has been shown to be getting weaker and disappearing from our universe in our perspective, but in my concept, gravity would be getting stronger and everything in our universe would be coming together and in about 13 billion years we will have a big collapse (BIG BANG). If this were the case than the stuff that we are looking for may in fact just be gravity seeping into our universe. So much for the dark matter & energy.
So you are working on a belief time moves?
If it is the year 2008 AD on earth as you perceive it. What is it on Saturn? The Andromeda Galaxy? The Death Star?
If you sit for 60 minutes on earth (based on a watch you are wearing). Would sitting 60 minutes on another planet take up more/less time?
🙂
I am not saying that time does or doesn’t move. I am saying that time is like an emense body of water with tides and currents that we are all bound to. Being that it is easier to perceive time one way, we do. It seems as thogh you are having difficulty with the idea of a 4th dimension. Where you are in one dimension will not affect another dimension.
>Astrofiend Says:
July 10th, 2008 at 7:58 am
Wow – Somebody stole my handle name! That’s a nice trick! That previous comment wasn’t actually mine. So to whoever that was, grow some balls and put your own name to your own comments. Or F_*K off.
P.S. The days of cheap gasoline are gone forever mate. Too bad.
I have absolutely no problems understanding a dimension of time. However, to work through your comments, one needs to understand how you are actually perceiving time, and at what constant you are placing it.
Think of using a time machine. Does the time machine MOVE to a period of time… or does a point in time move to where the time machine is?
Aodhhan
“Think of using a time machine. Does the time machine MOVE to a period of time… or does a point in time move to where the time machine is?”
Answer : Neither. Because a ‘time machine’ can never exist – unless you belive that a valid description of a time machine that only goes forward is a fair description of the universe in which we live.
Hey nerd boys, thanks for the education on “dark matter.” Of course we all know that our assumptions about gravity couldn’t be wrong so therefor they’s something out there called “dark matter.”
Indian mythological “Ishwara Tatva” is very near to Dark matter/ dark energy. The subtle matter “Ishwar Tattva” is not only the cause of creation or gradual synthesis of matter (dark matter) but also the progenitor of different fields.
Initially our Universe was filled up by such a medium The medium was distributed homogeneously through out the universe having properties as under.
It was made up of very tiny particle several thousand time smaller then electron, these momentum carrying particles were moving randomly in all possible directions with tremendous speed (of the order light travels in space). These particles ordinarily exhibit all such properties as considered in kinetic theory (dark energy).
These particles agglomerate in special circumstances to make bigger and bigger particles such as nucleons and other particles. Agglomerated big particles when come closer changes the local distribution of the medium , hence creating different fields popularly known as Gravitational, Electrostatic, Weak and nuclear depending on the relative size and distance of two or more particles
It describes the creation of Universe starting from the synthesis of first nucleon to the last stage of matter “The Black Holes”…………
just 5 simple yet complicated questions.
1. what are universes hanging on.?
2. if its on dark matter what are dark matters hanging on.?
3. are universes joined if not what occupies the gap between these universes.?
4. if we put all the uiniverses in a line or in a spehere where does this mean we have a starting point and ending point of this line or sphere.?
5. if yes whats beyond those line or sphere and what is this line or sphere hanging on?