How Well Do We Know What Stuff Is Made Of?

When we think of the “hard sciences,” physics usually tops the list.  A closer look at what physicists think the universe is made of, though, hardly makes the science look hard.  Look at this headline on PhysOrg, for instance: “Study finds there may be multiple ‘God particles’”.  The title refers, of course, to the famed Higgs Boson, not to some supernatural entity.  The Large Hadron Collider was hoping to find evidence of this particle that Nobel laureate Leon Lederman called the “God particle” because, he said, its discovery could help unify our understanding of the universe and “know the mind of God.”  But now, according to Fermilab scientists, there might be five versions of the Higgs boson (which hasn’t been discovered yet).
    Frank Close wrote a book review in Nature this week on this subject.¹  The book is Massive: The Hunt for the God Particle by Ian Sample.  He points out that particle physicists hate the label “god particle” that the media continue to give it, and notes that “many argue that it should not be called the Higgs boson because the concept has a longer history.”  It turns out there is as much sociology, theory and nomenclature at work as physics in the conception of what lies at the foundations of matter.  A sample:

Whereas the W and Z bosons that carry the weak force make use of this mechanism, the photon that carries the electromagnetic force does not; it remains massless.  Why this happens remains unanswered….
    Behind all this theory lies the work of another British physicist, Jeffrey Goldstone.  In his investigation of spontaneous symmetry breaking in 1961, Goldstone identified two bosons that played a part: one was massive, the other massless.  Both differed from the photon or W boson in that they lacked the intrinsic quantum property of spin.  Empirical evidence indicated that the massless Goldstone boson does not exist, flagging up a theoretical quandary that received much attention at the time from those who hoped to use the theory as a basis for uniting the weak and electromagnetic interactions.  The mechanism discovered by the three groups of physicists in 1964 explained how Goldstone’s massless boson could disappear, in the process giving a mass to the W boson that transmits the weak force.  It thus solved two problems for the price of one, and paved the way for the modern theory of the ‘electroweak’ force.
    Sample recognizes this work but overlooks its massive counterpart, which is where the excitement lies today.  The irony is that it also went largely ignored in 1964.  Brout and Englert made no mention of it in their paper, although they were aware of its manifestation in condensed-matter physics.  Guralnik, Hagen and Kibble suppressed it in their analysis, which was simplified to focus on the removal of its massless companion.  Higgs alone pursued it.  What is being called Higgs’s boson is, in effect, Goldstone’s massive boson.  Although at least six physicists can lay claim to this particular mechanism for generating mass, only Higgs realized the importance of the massive boson in testing the theory.

An understanding of the terms is not as important as a perception that various competing teams appeared to be playing with shadows in the dark, and making up concepts as they went along.  Can a particle really be a carrier of a force?  Can mechanisms generate mass just because a theory needs it?  Where is the mass coming from?  As useful as the terms and nomenclature become to theory, does nature owe any obligation to conform to human conceptions?  Did nature suddenly change properties this year when one Higgs boson became five?
    The intuitive answer to such questions is that of course nature didn’t change: we did.  Our scientific understanding of nature changed.  But then can we assume it is improving?  Is it evolving?  Is our understanding continuously changing, and if so, is there any point at which we can say we understand something with a sufficient degree of certainty?  At what point do we jettison things textbooks have been teaching for decades?  Can we assume we have the story right now?  What unforeseen discoveries in the next few years will have us regretting that what we are learning in 2010 is all wrong?
    These are serious questions, underscored by another example in New Scientist this week, “Anti-neutrino’s odd behaviour points to new physics,” as if all we need right now is a new physics (the hard science).  Reporter Anil Ananthaswamy wrote, “The astounding ability of these subatomic particles to morph from one type to another may have created another crack in our understanding of nature.”  This crack, he said, “cannot be explained by standard model physics.”  Granted, neutrino physics experiments are difficult, but a Fermilab test of theory produced unexpected results.  Jenny Thomas of University College London put a happy face on it: “If the effect is real, then there is some physics that is not expected.  Then there is something new that we don’t understand, and that’s fantastic.”

1.  Frank Close, “How the boson got Higgs’s name,” Nature 465, pp. 873�874, 17 June 2010, doi:10.1038/465873a.

Rejoicing in one’s ignorance may be an exuberant form of humility, but it is not the kind of progress one expects from multi-million-dollar investments in science.  Remember this next time you watch some TV program boasting about how scientists are on the verge of coming up with a “theory of everything.”  For an excellent background on the Standard Model and what it does and does not explain, read David Berlinski’s penetrating essay, “The State of the Matter” (The Deniable Darwin and Other Essays, Discovery Institute, 2009.)  Also recommended are the lectures on scientific reduction (23-24) in Jeffrey Kasser’s Teaching Company series on Philosophy of Science, which ask what value is being added to explanation when things get reduced to fundamental physics.  In another Teaching Company series, Steven L. Goldman (Lehigh U) in Science in the 20th Century –: A Social-Intellectual Survey provides a colorful look at the personalities and milestones involved in quantum mechanics, quantum electrodynamics and quantum chromodynamics and how our views of “reality” changed dramatically over the last 100 years.  In another Teaching Company series, Science Wars, he asked what we mean by ‘reality,” whether science can approach it, and what confidence we can have that our concepts of reality will remain intact a century from now given that they have changed drastically and repeatedly over the past few centuries.
    The reader should note that whether theories work is a separate question from whether they are true.  The Egyptians built the pyramids with remarkable precision while believing astrology.  We build cell phones and use GPS and lasers and a host of wondrous devices using quantum theory without a clue why nature behaves in the bizarre ways described by quantum mechanics.  How can something be a wave and a particle?  How can a photon pass through two slits at once?  How can two particles seem to interact instantaneously at a distance?  How can an observer play a role in the outcome of a quantum event?  We have no idea.  One mark of a good scientist is humility.