Will the LHC Create Dark Matter?

Hector writes in and asks about someone from Sheffield in the UK who says that the Large Hadron Collider (LHC) will create Dark Matter:

The massive ATLAS detector will measure the debris from collisions occurring in the Large Hadron Collider (LHC) which recreates the conditions found in the early universe during the Big Bang when Dark Matter was first created. If the LHC does indeed create such particles then it will be the first time that the amount of Dark Matter in the universe has increased since the Big Bang – the LHC will effectively be a Dark Matter ‘factory’.

Well, Hector basically wants to know if this is true, or if this is about as likely as your car safely tunneling through a brick wall? Well, the first part is true. The LHC accelerates protons in a big circle. Some go clockwise, some go counterclockwise, and they smash them together at two separate locations, where they have detectors to see what comes out:

The collisions are energetic enough that they can make massive particles from that energy (since E=mc2). They expect to be able to make particles that are up to about 100-500 times heavier than the protons that they started with. This includes the Higgs Boson that particle physicists are looking for, but it also includes other possibilities that might exist at those high energies, including Dark Matter.

And they’re right that if we put enough energy into the accelerator, we can make anything that has a mass! But they’re wrong that that’s the only way to do it in the Universe. Ever hear of a…. black hole? They spin, and they accelerate particles very quickly. Much more quickly than our dinky accelerators on Earth:

In fact, the amount of energy released when particles near a black hole smack into other ones are thousands of times higher than the LHC will ever produce, and so if the LHC can make dark matter, the “natural accelerators” that we see have been making it for billions of years. Also, the LHC, if we’re lucky, will make “thousands” of these dark matter particles, totaling up to a whole 10-20 grams of dark matter! OooOOOooohhh! (That was sarcastic.)

Warning: details ahead! But even if the LHC makes dark matter, I don’t think we’ll be able to know it. Why not? Because dark matter has a mass, but no charge. It also is stable: it doesn’t decay. So if you make dark matter in an accelerator, you don’t see anything! Because we can measure things very well, we will be able to say, “Hey, there’s energy missing from this!” But we produce things very commonly that just show up as missing energy. We call them neutrinos. Will the LHC be precise enough to distinguish between, say, the production of 2 neutrinos (a very common event; it happens 20% of the time whenever you make a Z boson) and the production of a dark matter particle? My sources say no, but it’s possible. In any case, that’s more information than you asked for, but look at me all motivated on a Monday!


  1. #1 benhead
    May 6, 2008

    Well, if it produces dark matter particles that are much more massive than neutrinos, it’d be easily detectable, right? There’s not just missing mass, but missing momentum. Many neutrinos would fly off in various directions, their momenta canceling to a small value, but one bigass particle would carry all its momentum off in one direction. (Leaving aside more technical ways to differentiate like an increased cross section when reaction energy is very near the particle’s mass.)

    Googling him, I bet he’s thinking LSP, as his bio says he’s “the chair of ATLAS’ supersymmetry working group.”

  2. #2 ethan
    May 6, 2008

    The problem is that neutrinos can carry momentum away, or they could not carry momentum away. When they’re produced in pairs (which they often are), there’s often no missing momentum, either. This is part of what makes it hard to distinguish.
    A lot of particle physics is about seeing your signal above your expected background. If the background is large and the signal is small, you may never be able to see it. And that’s the worry here — that even if you make it, you won’t be able to know it.

  3. #3 Jaymie
    September 9, 2008

    If we were going to die then it would be heaps more on the news and the scientist making it would stop now and they wouldnt go on with this whole thing

  4. #4 Bullshit artists
    September 9, 2008

    This conspiracy is a whole heap of bullshit. We might create a little world where there are little gremilins. that is all. no . big. bang.

  5. #5 C
    September 9, 2008

    so can i get a couple milligrams of enriched protons man, yaknnow, to help grow stellar pot

  6. #6 Chrissy-e
    September 10, 2008

    Little grimlins eh. Alls I have to say about it all is… If they don’t make black matter, and some what simulate the big bang I want my money back.

  7. #7 ethan
    September 10, 2008

    C — milligrams is asking for a lot of them. (It takes 10^21 protons to make one milligram.) But if you get it and proceed in your “growing” project, I’m getting an invite, I hope!

  8. #8 Valter
    September 11, 2008

    Dark matter aside please tell me what can a normal human being do with this big ring? Nothing from my point of view some previligious ones can play with it and that’s it. For this you spend billions… It won’t cure cancer, won’t make end starvation (maybe could if they used that amount of money for this purpose) etc… the only positive thing about this ring is that it actually uses superconductive magnets. Can we use this in our cars?

  9. #9 ethan
    September 11, 2008

    Valter, you can do the same thing with this big ring that I can. Nothing. Why? Because I don’t own it, and I don’t work there. But this is the most basic kind of “research” that goes into “research and development”. Can we use this in our cars? The answer is not today and not tomorrow, but possibly. When you look where no one’s ever looked before, you don’t know what you’re going to find.

  10. #10 Sili
    September 11, 2008

    And anyway – what’s the budget? About €5G? That won’t feed many people for very long. In fact, trying to fight hunger with that piddling sum will be much like giving a man the proverbial fish. I cannot say how, but the LHC (or basic research like it) will – if history is anything to go by – give the proverbial man the means to fish for himself.

    Okay – that’s enough metaphor stretching for me tonight.

  11. #11 planet facts
    November 9, 2008

    Ya, dark matter doesnt decay so no real way of finding out weather or not lhc will effect it becuase we dont have a way of getting the mass.

  12. #12 Thomas
    November 12, 2008

    hey [black holes] spin, and they accelerate particles very quickly. Much more quickly than our dinky accelerators on Earth”. The LHC is actually suppose to accelerate particles up to speeds of 669,946,012.4 miles per hour or ninety-nine point one percent of the speed of light. As far as we now nothing exceeds the speed of light and to reach almost !00% of the speed of light is pretty f-cking fast.

  13. #13 Kevin
    November 13, 2008

    Just another example of what scary times we live in. Corrupt leadership, Natural or man made disasters,food & resource shortage or monetary collaspe, something big is going to happen. I am making preperations now. This site is loaded with tips on surviving anything. <a href=”http://www.disastersurvivalist.com

  14. #14 David Johansen
    February 8, 2009

    Yep, dark matter does not decay. Dr. Tyson has some info on this on some site.

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