Thursday, 29 October 2009

Talking Particles

Imagine particles could talk. That a gluon pokes its head out of table to chat about the hard work it takes to get others to stick together. Sounds implausible? Anything is possible - even in the real, let alone the quantum world.

That is especially if you watched an obscure French children`s programme called Télé Chat in the 1980s. Which is precisely what Henri Bachachou did. And look at him now. Muon-mad, this Parisian works at ATLAS, the biggest of the experiments at CERN, with over 2000 people worldwide exploring the mystery of matter.

Fed on a diet of Télé Chat, with its lead characters, an ostrich and a cat, and its talking and walking particle zoo, Henri is a particle physicist, with an equally playful mind. But when you get him on the subject - or should it be the matter - of the muon, he becomes messenaic and no longer mild mannered and polite. For him, they are THE particle. In character, they are like an electron, but are 200 x heavier, and in fact their weight is in between an electron and a proton. Every second a 100 million muons are falling from the sky in cosmic rays. And because they are heavy, they can be easily detected, leaving very clear tracks, which are also known as spark lines, because they give off an electric charge.

Which also means that they are invaluable when they are artificially recreated in the LHC. Easily identifiable, they are also one of the clues for finding the Higgs, which is thought to give off muons. And they can pass through matter too and that includes your own body. In fact, a muon hole may be opening at your feet this very nano second - it's just that you cant see it - as muons cascade from the sky and fall from between floor to floor to floor. The world is opening up before you. You just don't know it.

That's how it feels when you are talking about particles. Suddenly you see such endless possibilities in the material world that nothing seems material ever again.

'Have you ever wondered why physicists are so indecisive?' asks Henri. 'Take them to an ice cream counter like gelatomania and you will find they cant make up their minds because they know the whole range of tastes available - and are thinking of the new ones which aren't there too.'

It all makes sense somehow. Talk the particular about a particle, and you have entered into a self-contained fairy tale, which contains its own internal logic of actions and context, but equally could very well not exist at all. And that is on this symmetrical side of the universe. Talk asymmetry, and then we really are talking Alice in Wonderland and through the looking glass. You enter the world of squawking squarks and smuons and sneutrinos...a Finnegans wake of words and playfulness which seems to make no sense at all....

...which may be why the elusive Higgs, whether it is prooved to exist or not, comes as a bit of a relief. A particle with a human name. For the ultimate invisible particle it has a particularly grounded name. But still, let's talk particles...I will find some more physicists who can do just that...and keep you posted.

Tuesday, 27 October 2009

Gravitys Rainbow

Talk to a physicist, and you always step into a different dimension. Unwittingly so. Its like diving into clear water and then seeing the stars. The light at first can be blinding, because the accuracy of their vision can be so acute. But then you adjust, dive deeper with them, and discover new vistas. The deep blue has never been more meaning-full.

So I find myself in a room with the man who is writing a paper which is about to change astrophysics. Everyone is standing by for his genius. But no. His bright lazer mind is switched onto other things. We are no longer in a room. We are notes on a musical score. He tells me how 10 years ago he finally learnt the piano. Now he can play Beethoven and it just tumbles out of his mind onto his fingers. You can almost sense he is listening to it, or indeed playing it when he tells me this, his love of this musical dimension is so intense. He tells me also that the way he learns the piece is by diving into it through its harmonic structure. That with the analytical mind of a physicist, he sees the patterns, engages with the harmonies, and totally understands every single note, the why and wherefore of its individual placing. And thus it becomes part of him. So much so, that when trapped in a boring meeting, he seeks refuge by playing a complex sonata in his head and his mind is elsewhere as the patterns rotate and spin.

But switch it all around the other way, and ask him
if music has changed his approach to physics, and he says, it soothes me. He uses it for pleasure. No more, no less. The beauty is the other way round - the way physics makes him approach music with his head, and then his heart comes into play too.

Somehow, at the end of our conversation which was really about something quite other - about Collide, the International Artists Residency Programme I am devising for CERN - it seems totally fitting that Luis volunteers himself for my Radio 3 piece to be a graviton. He of all people will understand the beauty of gravity. He has a levity and gravity which is totally beyond. That of a rainbow.

* Definition of a graviton. The graviton is a hypothetical elementary particle that mediates the force of gravity in the framework of quantum field theory. If it exists, the graviton must be massless (because the gravitational force has unlimited range) and must have a spin of 2 (because the source of gravity is the stress-energy tensor, which is a second-rank tensor, compared to electromagnetism, the source of which is the four-current, which is a first-rank tensor). To prove the existence of the graviton, physicists must be able to link the particle to the curvature of the space-time continuum and calculate the gravitational force exerted.

Monday, 19 October 2009

Sounding CERN

Think of particle physics, and you think of space, time and gravity as well as the invisible. Sound somehow does not fit into the equation. But of course, at CERN - where else? - there are experiments going on to give particle physics a sonic meaning as well as a visual one.

The young Austrian PHD student Kathi Viogt is currently working at the aptly named ALICE experiment, where time like in Lewis Caroll`s famous tale, is under investigation, as scientists try to liberate quarks and gluons. In the time process chamber, Kathi is turning pure data into sound. When you start thinking about it, of course it makes the most perfect sense. Instead of seeing simultaneous occurences and the split millionth, millionth of a second as particles collide or interact, why not hear them and use your other sense? Time and ears, rather than eyes take you further and the link between music and physics makes sense too.

The Time Projection Chamber contains wires which Kathi is using as if they were the strings of a harp. The wires capture and measure electrons coming from ionised gas set free when they are passed through chosen elementary particles. So when the electrons pass through, the `harp` sounds. The link between the Romantic poets and particle physics has never been clearer. Shelley`s vision of the aeolian harp, invisible except for the sound it makes as the winds of time pass through it, is now reborn in ALICE where you go backwards to come forwards in knowledge, in Kathi`s harp. It sounds just like CERN.

Tuesday, 13 October 2009

Of clouds and chambers

In the heart of CERN, in one of the many cavernous warehouses which dot this site, sits a stainless steel chamber. It is polished as brightly as a mirror, with portholes just like a bathyscope, ready for submarinal explorations.

Except this chamber is exploring the sky not the sea. To be more precise, the clouds above our head. It is not just the Large Hadron Collider which is switched on this November. The CLOUD experiment, first dreamt up 12 years ago, will create ice clouds and warm clouds within the steely embrace of this stainless cloud chamber, aglow with ultra violet light beams. The purpose is to understand the mechanism of how clouds form, and the clue is thought to be found in the seeds or cloud condensation nucleii, the little core of which remains the same in any of the trillions of droplets which make up a cloud.

How are they formed? At the moment the idea is theoretical - it has not been tested yet. But the thought and theory is that maybe the electrical charge from the naturally occurring cosmic rays, whose positively charged protons travel 10 million light years, interact with possibly the sulphuric acid in the air to form these cloud seeds. And if this is the case, then perhaps it may tell us more information about climate change and the way too in which clouds operate, protecting the earth. It makes blue sky thinking somehow seem far too unimaginative and the saying to have one`s head in the clouds a true compliment. Could anything be more sublime? As Jasper Kirkby, the physicist and architect of the CLOUD experiment say, looking up at the sky above the Jura mountains, flecked with mares tails or cirus in the Autumn afternoon, there is nothing more beautiful than a cloud.