Higgledy Piggledy

September 15, 2008

Brian Greene, everyone's favorite string theorist popularizer (well, except to those who really hate string theory), wrote an excellent Op-Ed in the New York Times last week explaining -- in crystal-clear language -- what scientists hope to find now that the Large Hadron Collider (LHC) is up and running. It's been written about plenty of times before, of course, but the actual science being done has been over-shadowed for several months now by the foolishness of all those Doomsday fears. So it's nice to see a handy recap in the Gray Lady's hallowed pages.

Particle accelerators are often called "atom smashers" in the mainstream media because, well, it sounds a lot cooler than something stuffy like the Large Hadron Collider. I'm generally in favor of hip monikers in science, but in this case, it evokes a misleading mental image: particles colliding and releasing energy in an "explosion," like an atomic bomb. In reality, when particles collide, they only release a very small amount of energy -- barely enough to propel a mosquito on the macro-scale of our everyday world.

But at the subatomic level, those collisions are strong enough to break atomic nuclei into their most fundamental parts. By analyzing the pieces leftover after the collision -- or rather, the patterns, or "signatures" they leave behind as they decay, since heavy particles exist for mere fractions of a second before decaying into something else -- particle physicists can learn a great deal about what subatomic particles were produced in these highly energetic collisions. It's a lot of collisions, according to Greene: more than half a billion every second or so. That translates into a staggering amount of data for physicists to sift through, looking for the telltale signatures. Really, it's amazing they've discovered anything at all, a testament to human ingenuity and perseverance.

The Higgs boson is one such particle, but so far, it's proven elusive, with only the odd hint here and there that it actually exists. If a Higgs event were to show up in the LHC data, it would look something like that mass of squiggles at right. And that would make Peter Higgs, the English physicist who first proposed it, very, very happy. (Among other things, he'd most likely snag a Nobel Prize.)

If you really want to annoy a particle physicist, go ahead and call the Higgs boson "the God particle." I dare you. Frankly, they are perfectly justified in being annoyed by it, because this is another catchy moniker that is profoundly misleading -- especially to folks with, shall we say, a certain casual disregard for facts. Case in point: conservative talk show host Rush Limbaugh, seized upon the term in April to castigate the LHC and scientists for trying to prove or disprove the existence of God. I kid you not -- this is from the official transcript:

"He's [Peter Higgs] looking for a particle to prove God. Dr. Higgs, please, just look out the window. You see that tree? You see the grass? Whatever is outside your window, all of it, it's God particles. Every aspect of it is God particles."

Oy. Talk about willful ignorance. Mr. Limbaugh, please, just go to your computer and type in "Higgs boson" in your search engine. See this link? And this one? Had you clicked on either one of those before shooting your mouth off, you would have quickly discovered the Higgs has nothing whatsoever to do with any deity, and everything to do with why objects have mass -- yes, that includes the trees and grass you love so much, as well as your own corpulent self.

You might recall from high school physics that one's weight is determined by how much mass you have, plus the force of gravity. But scientists want to know where mass comes from. That's where the Higgs comes into play. It's actually more of a pervasive field that permeates all of spacetime. The interaction of the Higgs particles that make up that field with other subatomic particles is what imparts mass. Greene gives a very lucid explanation of how this works:

"Perhaps space is pervaded by a field, much like the electromagnetic fields generated by cellphones and radio broadcasts, that acts like invisible molasses. When we push something in the effort to make it move faster, the Higgs molasses would exert a drag force -- and it's this resistance... that we commonly call the object's mass."

Different subatomic particles experience different levels of resistance, and hence have different masses. Photons, for example, have no mass and thus cut right through the "molasses" of the Higgs field with no resistance, whereas the top quark has a great deal of mass, and thus gets mired very easily. This is why we have tangible matter in the universe -- assuming the Higgs theory is correct, of course, which we can confirm with a sighting of the Higgs boson. Stephen Hawking, for one, has $100 riding on a bet that the LHC doesn't find the Higgs -- mostly because he thinks it'd be far more interesting physics if our current working model is incomplete.

Greene also tackles supersymmetry and extra dimensions in his Op-Ed article, which is definitely worth a quick read. And as for those mini-black holes running rampant and gobbling up the universe, he reiterates what should be obvious to all rational thinking folks by now: "It's a reasonable question with a definite answer: no."

Photo: Simulated Higgs event. Source: CERN/LHC/CMS, via Wikimedia Commons.

Comments

[IceBogan]

Most of Rush Limbaugh's mass comes from the kinetic energy of bound quarks in his protons and neutrons, not from Higgs interactions. QCD actually sets the scale!

[Sandeep singh]

Well its hard to understand all these make it more simple

[Brian Hodges]

Reading through Greene's piece (LOVED the Elegant Universe) I have a question perhaps you can answer. This Higgs field, the molasses or whatever it is sounds vaguely like the "ether" theory that physicists were following toward the beginning of the 1900's. Am I misreading that or is it just a difference in semantics.

[Jennifer Ouellette]

Well, I can see how they might sound kind of the same conceptually -- two things pervading spacetime -- but they're really quite different in terms of how they work. The "lumeniferous ether" was proposed in the late 19th century because back then, scientists believed light, like sound, needed a medium through which to travel. (Sound waves can't travel in a vacuum, light waves can.) It wasn't conceived as a "field" -- which means something very specific in physics -- but as an actual substance. This proved not to be the case (cf. Michelson and Morley's famed experiment).

Green's molasses analogy is a good one, conceptually, in that it gets across the basic idea of a very abstract mathematical concept. But analogies are tricky things because it's easy to get the wrong idea. The Higgs field isn't a substance in quite the same way; it's more the thing have gives us substance (mass). That's my understanding, at least. Scientists, feel free to weigh in with further clarification....

If you really want your head to hurt, start thinking about what the "fabric" of spacetime actually is: fine silk? Egyptian cotton? A cheap polyester blend? It's none of those things. Like the Higgs field, it's really just a mathematical framework on which to hang all of physics. It's necessary; to physicists, it's as real as you or me. But is it "real" in the sense of something we can feel, taste, and touch? Probably not.