I typically keep abreast of the news from the LHC (Large Hadron Collider), but this one slipped past me: On July 4, 2012, via a number of media, scientists at CERN announced they are 99% certain that the Higgs Boson has been found, based on two experiments that tested two methods they had hoped would discover it. Both methods had "worked".
How did I learn about it? More than a week later in Time! Since reading that article, I've perused news and science blogs about it. This morning, the query "Higgs" in Google yielded almost 2 million hits from July 4 until now. The same search in Google News produced 115,000 hits.
In the Time article in the July 23 edition (delivered the July 12), author Jeffrey Kluger's opening blurb states, "The elusive Higgs boson is at last found—and the universe gets a little less mysterious." I wonder about that.
The Higgs particle is being called a boson. According to the Standard Model of particle physics, everything we know about is composed of either bosons or fermions. Matter is made up of fermions, which are said to obey Fermi-Dirac statistics. A key characteristic of fermions is that they can collide, because no two of them can occupy the same space at the same time. Familiar fermions are electrons, protons and neutrons. Bosons mediate the interactions of fermions. Bosons are said to obey Bose-Einstein statistics, and they do not collide with one another, only with fermions. Any number of bosons can pass through the same location simultaneously, which is why light can be focused without limit, for example.
Light (including visible light, radio, x-rays and so forth) is composed of those bosons called photons. They mediate the electromagnetic interaction and are massless. There are three other interactions:
- The "strong" interaction, mediated by "gluons" that bind together the quarks inside nucleons (protons and neutrons) and mesons and all the "resonance" particles derived from them. Gluons are massive, so their interactions are short-range.
- The "weak" interaction by which protons and neutrons exchange identities, mediated by massive particles called W and Z.
- Gravity, which may or may not be mediated by a theoretical boson called a "graviton". If it exists, the graviton will also be massless, because gravity has no distance limit. Gravity is, to date, not included in the Standard Model.
c. Thus a photon has momentum, so a "solar sail" would work by transferring momentum from the photon stream to the sail material.
Weight is the resistance to acceleration caused by gravity. Interestingly, though massless particles cannot have weight, they do respond to gravitation. Their energy content, as defined by Einstein's Equation, E=mc², is equated to a theoretical mass that responds to gravity. This is why I question whether the graviton exists, or might be a boson. No other boson-boson interactions are known…except that between the Higgs and the gluons and W and Z, that produces their mass!
Do you see how tangled this is getting? So what is the Higgs particle, really? It appears to have mass itself, about 152 times as much mass as a proton. Thus the Higgs must interact with itself! So far, the explanations I have read are quite unsatisfying. Higgs particles are described as mediating a Universe-filling "Higgs field" (even though this implies they ought to be without mass). Particles have a greater or lesser tendency to suffer "drag" as they move through this field, and this drag is their mass. Photons zip through without any drag. This kind of explanation may be a roughly useful analogy, but it sounds pretty peculiar to me.
On the other hand, if there are gravitons, they do "drag" on the photons, because the gravitation of a black hole can trap photons and even reverse their direction. Anywhere outside the event horizon, photons travel at speed c, but their wavelength lengthens as they make their escape up the gravitational well. Right at the event horizon, photons are stationary, somehow! Inside the event horizon, they seem to be dragged backward by, so I have read, an inflow of space that exceeds c. No wonder Einstein didn't like the notion of black holes, even though his general theory of relativity predicts their existence and certain of their properties.
Perhaps the Universe has gotten "a little less mysterious", but numerous mysteries remain. Thinking about the reported "mass" of the Higgs particle, I must conclude that the mass is a temporary resonance, required to hold the particle together when it is teased into view by the enormous energy of the collision that extracted it from wherever it was hiding. In its "native" state, the Higgs must be massless. Further, it is likely that it is not affected by gravity. Otherwise the Higgs field would be as clumpy as the visible Universe, and the mass of any particular particle type (such as a proton) would not be a constant quantity. I suspect that experiments to determine such things will require an instrument quite a bit more powerful than the $10 billion LHC. It is too bad that the SSC in Texas was scuttled.