Today, scientists at the Large Hadron Collider announced that — after a year of sorting through their petabytes of data (debris from protons smashed together at tremendous energies) — they had excluded lots possibilities and found a hint of something interesting in their hunt for the particle known as the Higgs boson. But, so far, there is nothing conclusive to report, nothing to write home about, nothing worth a call to the Nobel Prize committee.
To understand why this search is so important we have to step back a few paces and recall something about the Higgs. Marcelo and I have both written on the search for the Higgs before and to quickly understand its importance you have to note two points.
The first is that the Higgs is the only critical player in the Standard Model of particle physics that remains unseen. The Standard Model is a towering intellectual achievement through which we understand all directly observed forms of matter and energy (except for the Dark Matter and Dark Energy; another story, indeed).
The second point to note is that Higgs is more than just a particle, it's a mechanism. Discovered simultaneously by six different researchers in 1964 (including Carl R. Hagen of the University of Rochester), the mechanism that came to bear the "Higgs" name is the means by which some particles gain their mass and others don't. Since mass is a really elemental property of elemental properties, the Higgs mechanism is an elemental hinge on which much of particle physics swings.
One of the principle justifications for building the $9 billion LHC was the discovery of the Higgs and the exploration of its properties.
There are various predictions for the mass (or energy, given E = mc2) of the Higgs particle. The job of LHC physicists in this first year of data taking has been to comb through a wide range of energies and look for signals of the creation and decay of the Higgs. I say "creation and decay" because the Higgs won't just pop out of the data and announce its ready for examination.
As the old metaphor goes, particle physics is like smashing two watches together and figuring out how they were built by exploring the debris from the collision. Physicists at the LHC are smashing protons together (lots of them) and sorting through the particles which emerge in hopes of finding evidence that a Higgs briefly existed before it spontaneously transformed into some other particle, which may then have transformed into yet another (that's just how life works at a thousand-billionth of a meter).
Which brings us back to today's announcement. The physicists at the LHC have been taking data for a year (they expect to be taking much more over the next few years). They have reams of data from reams of collisions to sort through. The great thing about being at the University of Rochester is I could go down the hall and talk about the LHC experiments with my high-energy physics colleagues (who have been instrumental in building some of LHC's instruments). Generous discussions with Regina Demina and Aran Garcia-Bellido helped me sort out exactly what today's announcement meant. With all that data taken, any statements LHC physicists make will have to be couched in the language of statistics. The question will not be just, "How well do I know that I saw what I saw?" but also "How well do I know that I did not see what I expected I might have seen?"
Yeah, it's complicated.
In today's announcement groups representing the two main LHC experiments (ATLAS and CMS) said they had excluded the existence of Higgs particle over a huge region of higher energy (= mass). While that is important, many physicists felt they had good reason to expect that such a "massive" Higgs should not exist, unless something exotic was going on. So, if this wide region was excluded, then what's left?
A hint of something very interesting.
At an energy of about 125 GeV (giga-electron volts) physicists see an excess of events (signal) above what they would expect from the usual background noise. With the amount of data they have now, the excess signal is large enough to be statistically interesting (around 2.4 – 3.6 standard deviations, for those who like that kind of thing). The fact that that both experiments see the same signal at the same energy/mass makes the news even more interesting.
But — and this is a big "but" — this result could easily disappear as the LHC continues its operational search over the next few years. As more data comes in, the statistics of the search become more refined and the conclusions scientists can make from the data becomes more conclusive. So, for now, the news is a giant "maybe."
Maybe physicists have discovered the so-called "God Particle." Maybe it's in this 125 GeV energy zone, where many theorists think the Standard Model would have predicted it to be (though at this energy some new mechanism is needed to keep the Higgs stable and prevent the entire universe from exploding. That's yet another story we'll have to leave 'till later). Maybe, maybe, maybe ...
And there is the moral of the story. It's a big moral, so get ready.
The Higgs might be found. The Higgs might not be found. After all that time and all that effort, the Higgs might not exist in the energies we can probe. Or, even more importantly, it might not exist at all. While the lack of a Higgs would, in some way, be exciting, pointing us in an entirely new direction, it would be dishonest not to admit that it would also be a blow. There are many scientists who have invested their careers (and a lot of public's money) in this work. What would happen then? What would they do?
The answer is simple: stand up and tell the truth.
If a year from now the 125 GeV signal disappears with more data, then the scientists at the LHC will stand up and say "Its not there." Then the chips will fall where the may. It would be a big, big deal. You can imagine lots of folks would be much happier if the signal remains. But we are not in the business of hope. We are in the business of entering into a permanent dialogue with nature. The one hope we do have in that dialogue is our honesty.
"This is what we saw. This is what we think it means."
That commitment to the truth of what is seen sets science apart from politics. That commitment to the observed truth is something we need to be mindful of as we continue our debates about all the other ways science and culture intersect, from hydro-fracking to climate change to debates about evolution. The world speaks for itself and if you are wrong you are wrong. You just have to suck it up.
Taken in that light, the "maybe" of today's LHC's announcement may just be the most important news of the day.