Not only is today “Independence Day” here in the US, celebrating 236 years since a group of American rabble-rousers declared independence from Britain, it is also now the day that the Higgs Boson discovery was announced at the LHC in Switzerland. (Read about it in the Washington Post and the NYTimes as well.) In one of my previous lives I was an experimental particle physicist. For about 13 years I labored with wrenches and computers at Fermilab trying to pry information from the gigantic pile of data we amassed from colliding proton and anti-protons inside the Dzero detector. I was there in 1995 when we announced (with our older-sister experiment, CDF) the discovery of the top-quark.
If you follow any of this sort of thing, you’ll know that the hunt has been on for a long time. (CERN’s publicity machine has also done a good job of keeping it all in the news as well.) If you’re wondering “what the heck is a Higgs Boson?” there are lots of nice explanations of the basic ideas of it lying around the web — Dennis Overbye at the NYTimes put together a nice compilation in his post to the Lede today. In many ways, it’s so much like getting to the moon. You see it there, in this case in your mind and, importantly, in your mathematics, and you go looking for it, wanting to visiting it, to, in some sense, hold it in you hands and confirm that it’s there, that it happened. It’s the essence of exploration and experiment — the seat of confirmation. The difference with the moon is that it was a live option that the Higgs was a mathematical mirage. Indeed, for an experimentalist it might have been much more satisfying to have it be excluded, in which case we’d find ourselves lost and need to find our way again. Few people, certainly none of the scientists and engineers developing the technology to travel to the moon, entertained the notion that the moon might be a cosmic figment and not a big rock. No, here it’s hard to deny what Brian Greene said in one of his interviews, that it’s a great day to be a theorist — mathematics really does tell you something about reality. (And again, the experimentalist in me stands up and says “but it wasn’t reality until we found it, damn you!”)
The discovery is also wonderful because, though the Higgs is a particle, the discussion of it has, properly, been emphasizing that it really is the sign of a universe-permeating field which imbues objects with mass. Quantum field theory has been around for a very long time — nearly as long as quantum mechanics. Electromagnetic theory even longer. Yet, we often don’t grapple in the public media so much with the notion that these fundamental particles, these photons and quarks and electrons, are manifestations of fields. We toe up to that a bit with the discussions of the Higgs. Indeed, there’s much to chew on philosophically here. The particles that we observe in QFT are manifestations of the fields and do not compose them. So, you can’t interact with the field without colliding with a particle, but, you cannot have the particle doesn’t exist apart from the field — they come together. The Higgs brings along things near and dear to our hearts — mass. Mass is a manifestation of the interaction of other particles with the Higgs field. Photons have no mass because they don’t interact with the Higgs field and it also why they travel at the maximum speed of anything in the universe. A heavy particle is simply one that is dragging more in the Higgs-field soup. So now we have objects imbued with this characteristic, mass, that isn’t a property of them like charge, but a consequence of their interaction with their surroundings. Furthermore, the objects of the universe interact with one another in proportion to that mass (it’s gravity) and that interaction is unique enough to firmly distinguish one thing from another, be it elementary particles or blocks of iron at the gym.
I think I feel a philosophy of science episode looming…