Friday, December 16, 2011

Higgs hunt

In the olden days in Australia (that's to say, when I was a kid), a simple gambling game called Two-up consisted of placing bets on throws of a pair of pennies. Obviously, there were three possible outcomes:

1. Two heads:

2. Two tails:

3. One of each:

Now, let me ask you a simple question: What is the probability of the last-mentioned outcome (one coin landing tails, and the other heads)?

Did I hear you say one-out-of-three? That answer would be wrong. The right answer, of course, is one-out-of-two. In mathematical jargon, the probability of a mixed heads-and-tails outcome is 0.5.

That banal Aussie Two-up demo was a prelude to one of my favorite science stories. Once upon a time, during a lecture in a university of present-day Bangladesh, the Calcutta-born mathematician and physicist Satyendra Nath Bose happened to make the above-mentioned mistake. Unbelievably, in front of his surprised students, Bose exploited unwittingly the erroneous one-out-of-three probability in order to provide a convincing explanation of a certain experiment in the domain of quantum statistics.

In a nutshell, quantum happenings and explanations are so weird that you can even obtain the right answers by using what might appear to be crazy reasoning... as long as everything remains mathematically immaculate. We might say retrospectively that, not only was there method in the temporary madness of Bose, but superb madness in his very method. In any case, Bose's initially mixed-up meanderings gave rise (I'm cutting a long story ultra-short) to what has since become known as Bose-Einstein statistics. This extraordinary Bengali mathematician and physicist (who needed Albert Einstein's personal recommendation in order to get a university job, since he didn't have a doctorate) finally obtained cosmic recognition through the naming, in his honor, of a subatomic particle: the boson. What a lovely story!

Let's jump forward to more recent times. Peter Higgs is an 82-year-old English theoretical physicist. Long ago, he happened to be enrolled in a secondary school near Bristol: Cotham Grammar School. The list of distinguished alumni of this quite ordinary establishment is astonishing. One of them was the Nobel laureate Paul Dirac. That list now includes the name of Peter Higgs (represented here in a portrait by Ken Currie, 2010):

His surname qualifies a fabulous elementary particle that has become the Golden Graal of contemporary physics: the Higgs boson. These days, most cosmologists believe that this theoretical entity should in fact exist, and that's why the international Cern research institute has built a gigantic machine, located on the Franco-Swiss border, that will hopefully demonstrate that the Higgs boson is a tangible reality. (Maybe "tangible" is not an ideal adjective, since it's not as if you might slice a Higgs boson in two with the help of a Swiss Army knife, or run into such a particle while strolling around in the streets of Geneva.)

The funny thing about this affair, to my mind, is that everybody carries on talking about the Higgs boson as a particle, as if it were a tiny bit of matter. That's a little like referring to light as photons. While this usage is perfectly correct from a quantum theory viewpoint, you wouldn't normally ask somebody to turn on the light by saying "Please beam us a stream of photons". It's a fact that the existence of the Higgs boson will indeed be demonstrated one of these days, we hope, by a collision of particles that might be imagined like this:

At a press conference this week, Cern representatives revealed that the mass of this particle appears to be about 125 gigaelectronvolts, and that its existence will probably be revealed with certainty as early as next year. To understand why the capture of this elusive particle would be so prized by cosmologists, it's preferable to think of the Higgs boson, not as a tiny bit of matter (so small and ephemeral that we cannot possibly comprehend it), but rather as a field. As is the case for photons, quantum theory enables us to switch freely from a particle-oriented to a field-oriented interpretation of bosons. You can look at bosons from either way, whichever happens to suit you. We're intuitively familiar with everyday fields such as magnetism (or rather electromagnetism) and gravity. Higgs bosons, viewed as a field, are extraordinary (Can any entity in the Cosmos be thought of as ordinary?) since this field pervades, totally but invisibly, all the interstices of the Cosmos.

The Higgs field is crying out to be revealed—almost certainly through a corpuscular experiment at the Cern—for the simple reason (Can any explanation in the Cosmos be thought of as simple?) that the presence of this field would be a gigantic step towards our "understanding" (Can anything at all in the Cosmos be truly understood?) of a totally mind-boggling notion: namely, the creation of being from nothingness.

At the end of that last paragraph, I borrowed the title of a famous book by Jean-Paul Sartre. But I have to add that this illustrious French philosopher would have been sadly incapable, in spite of his alleged brilliance as a thinker, of appreciating even the present modest blog post, because philosophers of Sartre's kind never imagined for an instant, strangely, that science might have anything to do with explaining the realities of the Cosmos and of our human existence. And so they never bothered to learn mathematics and physics, just as they weren't particularly intrigued by biology, DNA, genetics, computers and all the rest.

POST SCRIPTUM: Not surprisingly (But isn't everything in the Cosmos both surprising and unsurprising, simultaneously?), bosons and quarks are not far removed from snarks and boojums, as presented in the celebrated nonsense poem—an "agony in eights fits"— by Lewis Carroll. The title of my blog post, Higgs hunt, evokes mildly this association. I hope that readers will have appreciated my avoidance of an utterly ridiculous expression (the God particle) that mindless media folk have often used to designate the Higgs boson. I would have gladly taken a timid step in that silly direction, however, by referring to the Higgs boson as the Godot particle… since everybody is surely waiting for it.

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