Don Lincoln

 

On his book The Quantum Frontier: The Large Hadron Collider

Cover Interview of May 13, 2009

A close-up

While The Quantum Frontier is not a single-topic book, perhaps no question has received as much attention as that of the enigmatic Higgs boson.  This undiscovered particle is always mentioned in the thousands of articles describing the LHC that appear in newspapers and popular science magazines.  But precisely what this particle is, and why it’s important, is not always talked about.  That’s a shame—without this particle or something equivalent, the universe would be a very different place.

The last couple of decades have taught us that the matter of the universe is made of unfamiliar subatomic particles called quarks and leptons.  Two kinds of quarks (confusingly called up and down) make up the protons and neutrons of the nucleus of atoms, while the electron is the most familiar lepton.  There are two carbon copies of these particles and all of the particles have radically different masses.  The very light electron (the lightest of the class of particles that takes its name from leptos, the Greek word for light) has a mass of 0.05% that of a proton, while heaviest of them all, the weighty top quark (a copy of the up quark) has a mass 175 times heavier than the proton.  Why should this be?

In the 1960’s, theoretical physicists were able to invent sensible theories that could predict many of the phenomena we observe.  However these theories required subatomic particles to be massless—a distinctly not sensible idea.  To return sense from nonsense, a proposal was put forth in 1964.  Peter Higgs integrated some earlier ideas with his own and suggested that there might be a previously-undetected energy field in the universe which has come to be called the Higgs field.

It is not obvious how the Higgs field can result in a particle, but a water analogy may help.  Water is a liquid and fills up all of a container in which it is placed.  One might call water “continuous,” as it is not at all trivial to go into a pool and find space “between water.”  And yet water is made of molecules consisting of two hydrogen and one oxygen atoms (H 2 O).  Water consists of tiny “smallest bits” of water and still looks continuous when viewed at human-size scales.

Similarly, the Higgs energy field consists of countless Higgs bosons.  Finding such a boson is a crucial test of Peter Higgs’ idea and it is this search that is the most reported of the many things the LHC scientists are looking for.  Reading The Quantum Frontier should give a very good idea of how scientists will know when they’ve found one.  (If, indeed, Higgs bosons are there to be found at all.)