Back in July of last year scientists at CERN were finally able to say that they had enough evidence to say that they had discovered the Higgs boson. This particle was one of the last to be found as predicted by the Standard Model of particle physics. It comes from what is termed the Higgs field, which was introduced by physicist Peter Higgs to explain the origin of mass in some elementary particles. The Standard Model without it would have all particles be masses, and they would travel at the speed of light. If that was the case, there would be no interesting matter, let alone life.
Now that the particle, and its field, are known to exist, there has been more and more work to refine the results and learn all the properties they can. Currently the Large Hadron Collider (LHC) is shut down for upgrades, but there is still plenty of data to analyze and research to do with it. As of now, the two major detectors have determined the mass of the Higgs to be about 125 GeV (according to CMS) and 126 GeV (according to ATLAS), and their error bars overlap. This was a great success, and continuing analysis will certainly help us refine what we know. To make things sound a bit odd, by studying the Higgs field, we are studying the vacuum; all this research is to explore “nothing” with the best instruments ever built. (Donations are welcome; please support a local grad student today.)
And perhaps knowing this mass even better will tell us something about the fate of the universe. Will Flash Gordon save the world again? Will Luke resist the Dark Side of the Force? Will the cow jump over the Moon?
Actually, there is the serious consideration that the mass of the Higgs boson will tell us if the universe will destroy itself. If the mass is too low, DOOOOOM!
Or, at least that is the impression from some of the latest news reports on the subject. What is going on here? This was fairly new to me, so fortunately I had help from mein Schatz in helping me understand this (love you!). The key thing is that the Higgs will have some level of self-interaction. After all, the particle has mass, so it should interact with the field that it comes from when excited enough. So there is a direct relationship between the mass of the Higgs boson and its self-interactions.
Now, another thing is what is happening to that level of self-interaction as a product of the energy of collisions, and at high enough energies the coupling would become negative, making the vacuum unstable and releasing a lot of energy. Think of it like this: we think of the Higgs field that describes the vacuum and the energy in it; the shape of the potential is shaped like the bottom of a wine bottle or a sombrero. It is most stable at the bottom, where we and most everything we know hangs out. However, if the coupling becomes negative as mentioned, then there can be an even lower energy state, and then the particles in that energy potential would fall to the new, lower state. Because of that, much like how you pick up speed when going down a hill, the particles dropping to the new, lower energy state have more energy (they speed up), and that we call heat. So, it means that in this unstable situation, particles in that region will release a lot of energy.
Now, this would all be at the quantum level, so no big dear, right? Problem is, this state of the vacuum would be at a lower energy, and the universe always tends to the lowest energy state–go lower, get more stable as you are more likely to stay in a valley than at the top of a mountain.
This would lead to a bubble growing up and taking with it the entire universe at the speed of light.
Now, there is a limit to high up the energy can go, and because it is not infinite there are limits on the mass in which the vacuum is stable. That limit is called the Plank energy, which is an energy of about 2 billion Joules or about 10^28 electron volts of power, which is about 10 trillion, trillion times more energy than in the collision at the LHC. There is some uncertainty as to what the limit is because of uncertainties in the mass of the top quark and other parameters, but the limit seems to be at around 125 GeV. However, that tipping point is just what we measured for the Higgs!
OK, so should you be worried about this? Perhaps you should be as worried as you are about total protonic reversal, and in fact some physicists are looking forward to it. For one thing, there are models of super-symmetry that have mechanisms to prevent such utter destruction. Now, all such models could be wrong, but the universe has been doing the sorts of experiments we need to test this already for billions of years. Considering all the high-energy event happening all across the universe all the time, and we haven’t had this sort of cosmic destruction, it indicates either that the Higgs is massive enough or there are other mechanisms in play that will save us. These are points that are not well-represented in the news reports, unfortunately, leaving us only with the potential for Armageddon on an amazing scale.
So, instead of shouting “DOOM”, we either have a massive enough Higgs or a low-mass Higgs and have empirical support for super-symmetry. Either way, this is good news. So please, don’t claim that CERN will destroy the world (again) or make up another crap doomsday prediction. The last (Maya) one didn’t go well, so let’s not have that again.
Note 1: Though I had help and did some research, there may be mistakes in my explanation at a subtle level. All errors are my own and will be corrected if pointed out.
Note 2: many news outlets quote from physicist Christopher Hill. He works at my current alma matter and participates in the CMS experiment. I used to work on ATLAS, so let that “rivalry” be known. 😉