Wednesday, July 11, 2012

The God(less) particle

Jul 11, 2012
By Andy Ho

THE scientific world was abuzz last week with the 'God particle'.

Or, at least, that was how the world media hyped it up. Scientists at Europe's US$10 billion (S$12.7 billion) Large Hadron Collider called a press conference to announce their discovery of a subatomic particle called the Higgs boson.

A Nobel laureate in physics decades ago gave it this evocative name, which scientists now hate. But the legions of non-physicists who logged in to follow 'live' the online streaming of their press conference on July 4 must have largely been attracted by this moniker.

Let's be honest about it: few non-physicists would have bothered with a press conference about bosons, fields and 'five sigma', terms that featured liberally in the proceedings.

To be sure, it was a significant finding. And since Big Science requires Big Money, the media coverage will work wonders for its funding in Europe. Legislators will now be suitably intimidated by (their lack of understanding of) the God particle to suggest reducing Collider funding any time soon.

Trouble is, there isn't anything particularly 'godly' about this particle. So what is the Higgs particle?

To explain it requires some backgrounding. The concept of that seeming emptiness we call 'space' actually contains fields invisible to the eye, like electromagnetic fields and gravitational fields. Every point of space said to be empty contains these fields.

Particles are packets of energy which interact with one another and with space (fields). When particles interact with fields, there is exchange of energy, which can be transformed into particles with or without mass.

This exchange of energy occurs through the agency of something called the exchange particle. For example, you may recall from high school science that when electrons orbiting an atomic nucleus drop from a higher orbit to a lower orbit, a photon - which is a massless particle or packet of light energy - is emitted. When a photon collides with and absorbs another, an electron can jump up to a higher orbit. Thus the photon is an exchange particle of the electromagnetic field.

All exchange particles are species of what is called a boson particle. The Higgs particle is one type of such a boson. Scientists came up with a theory that such a particle must exist, in order to explain why some particles like photons have no mass whereas others like protons and electrons which make up matter do have mass.

Using their best model called the standard model, physicists can describe every kind of particle in the cosmos and how large their masses should be, including no mass. But the model cannot explain why mass should exist at all.

To get around this, physicists postulate that there is something called the Higgs field in 'empty' space that produces mass. If particles (like neutrinos) moving through this field can interact with it, the 'drag' gives rise to mass. If particles (like photons) moving through a Higgs field cannot interact with it, then they won't have mass.

Now all you have to do is prove that Higgs fields do exist.

Using the standard model, physicists know the mass that a Higgs boson must have - if it exists. If you detect Higgs bosons of this precise mass, then you would have proven that Higgs fields do exist. This is what the European scientists said on July 4 that they had achieved.

How is the Higgs boson related to the Higgs field? It's somewhat akin to the relationship between the pattern of vibration of a guitar string to the string itself. To find out how tightly strung up the string is, just pluck it, and the sound (waves) emitted will tell you so. Likewise, to know about the Higgs field, collide one proton with another as they did at the Collider and study the waves that result, which are Higgs bosons.

Because such collision data is very complex, errors creep in very easily. To be sure that a particle's mass detected is that of a Higgs boson and not random statistical chance, scientists use a measure called sigma. One sigma means there is a 32 per cent chance that your results are due to happenstance and not the real phenomenon. Two sigmas equal about 5 per cent chance your data is not real. This drops rapidly so that at five sigmas certainty, you are 99.999 per cent sure you have really found what you were looking for, that your results did not occur by random chance. This is what the Collider scientists declared recently, that their data was five sigmas sure to be correct.

So they were almost 100 per cent sure they had found the Higgs boson, which proves that Higgs fields do exist. And this, Dr Lawrence Krauss, a theoretical physicist at Arizona State University says, explains how all mass and matter came into existence out of nothing since space is nothing - though it really contains fields.

In his recent book, A Universe From Nothing (2012), Dr Krauss, like many in the field, explains that the Higgs field permeates all of space and brought into existence, through the Higgs boson, the stars, planets and people. Some may consider it the 'God particle' for explaining how mass formed. But Dr Krauss views it as the 'God-less' particle that would explain the existence of everything without a Creator.

If we live and move in a universe that came out of nothingness, the meaning of life changes radically and all religion is claptrap, Dr Krauss asserts.

Yet proving that Higgs fields exist (because you have proven Higgs bosons do), thus explaining how mass came into being, simply pushes the question back one step. We now must ask: 'Why were there Higgs fields - and particles - there in 'empty' space in the first place?'

But Dr Krauss takes for granted the laws of quantum mechanics, which Higgs fields have to obey and do obey for mass and matter to come into existence. He only alludes to these laws of relativistic quantum field theories in passing in the last few pages of his book. He does not ask where those laws that govern what arrangements of quantum fields are possible and which aren't come from.

Did some other property - animate or inanimate - give rise to those laws or to the fact that the universe is made up of particular kinds of fields? So the Higgs boson discovery does not prove creation from nothingness. Nor, of course, does it prove the existence of a Creator, despite the media dubbing it the God particle. What it proves is just that mass comes from Higgs fields, which is a long way from proving whether there is a Creator or not.

[Thanks Dr Ho for explaining the issue so clearly. Although the last defensive bit about the Creator was unnecessary. :-) ]

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