Weekend Post - The Higgs

It had to be the Higgs boson, what else could I write about?

The recent discovery of persuasive evidence of the existence of this mysterious sub-atomic particle is one of the biggest discoveries in physics in recent decades. It really is a big one. Strangely it doesn’t actually introduce anything new to our knowledge of the universe but it does confirm our current understanding of how things work. For now.

This current understanding is usually called “The Standard Model”. This describes the different types of sub-atomic particles that comprise everything that we can see and sense. It describes particles such as electrons, the quarks that make up protons and neutrons, photons and a range of bizarre things that collectively comprise matter and it’s non-identical twin, anti-matter.

One mystery that the Standard Model couldn’t fully explain was mass, the amount of physical “stuff” that each particle comprised. Some had lots of it, some just a little, others none at all.

In 1964 Peter Higgs, a physicist at Edinburgh University, predicted the existence of an energy field throughout the universe that would explain why things had mass.

Higgs suggested that certain particles have mass only because they interact with this field, now called the Higgs Field, as they pass through it. The more particles interact with the field, the more they develop mass. Those that interact travel slowly as a result, those that don’t continue travelling at full speed, the speed of light. Photons, the particles that make up light, whizz around at blinding speeds, the particles that make up you and me lumber around like elephants in custard.

But all of this has been theoretical until recently. Two competing laboratories, Fermilab in the USA and CERN who host the Large Hadron Collider in Europe have been doing their best to discover evidence of Higgs’ prediction using a technique that doesn’t sound that advanced. Each has constructed massive particle accelerators that shoot atomic particles at each other at speeds very close to the speed of light and see what happens. You could argue it’s a bit like trying to work out how a cellphone works by repeatedly hitting it with a hammer but it is actually more thoughtful than that.

CERN, having a bigger and more powerful accelerator were the ones most likely to make any discovery and that’s what appears to have happened. Last week they announced that they had found convincing evidence amongst all those particles smashing around of something that really looked like a Higgs boson, one of the particles that makes up the Higgs field. Like all decent scientists they’re treading cautiously, they’re not actually saying they caught the real thing yet, they’re just saying that they saw something that was “consistent with” a Higgs boson. Like proper scientists they had done the maths properly. The chances of what they saw not being a genuine particle was at the “5-sigma” level of certainty, 5 standard deviations away from the mean, in other words there’s only a 1 in 3.5 million chance that this isn’t genuine. As the Director General of CERN said: "As a layman I would now say I think we have it."

There is one major misunderstanding that many people have experienced about the Higgs boson. For some unaccountable reason, much of the media decided to refer to it as the “God particle”, a reference to a popular science book published twenty years ago. The particle of course has nothing to do with God, religion or anything “spiritual”. Higgs himself has rejected the term, not because he is religious, in fact he’s an atheist, but because he doesn’t want his theory to offend people who have religious sensibilities.

So where do things stand, now that we’re confident the Higgs field exists?

The Standard Model is still with us, but there’s still a lot of things we don’t know. Perhaps the most mysterious is the existence of “dark matter”, the matter that our understanding of physics says is out there but we just can’t see. About 95% of the universe is invisible.

Unfortunately, covered up by the almost hysterical reaction to the Higgs’ discovery was another, much quieter science news story, one that’s perhaps just as important. A paper published in Nature announced the first observations of wispy filaments of dark matter between galaxies connecting the much larger clumps of dark matter whose enormous mass give the universe it’s gravitational structure. While the word “filament” might imply that these things are small and insignificant in fact they’re massive. The filament identified is estimated to be a billion trillion kilometers long and has a mass a hundred trillion times greater than our sun. So not exactly small.

The wonderful thing is that in the same week scientists have discovered something unimaginably small and something else unimaginably massive, both of which were predicted but not yet spotted. Both perfect examples of the scientific method. Create a theory that explains things, make predictions from it, identify how it can be tested and then sit back and wait.