High definition digital video: 4.31 mins.
In this tiny film we have tried to convey the essence of the project. With thanks to the team.
Piano - Prof Ed Hinds, playing Bach, Prelude and Fugue 17 from the Well Tempered Clavier.
Double Bass - Dr Ben Sauer playing an excerpt from Sibelius Symphony No. 2, beginning of the second movement.
Footage of the yellow precessing electron - programmed by Dr Mike Tarbutt.
Electrons are spinning things.
Whirling around the outskirts of every atom they give form, colour and information to our world.
You probably imagine them to be round, defined by a single number. We all expect beautiful symmetry, but our best theories need quirky asymmetry to explain why we exist. We imagine that nearly 14 billion years ago, our universe began symmetrically, with as much matter as anti-matter. This would cancel out in spectacular annihilation, removing all stuff, leaving no potential for us, just a universe of spreading light. To solve this problem of existence, amongst other conditions, we think that the shape of the electron needs to be an egg.
The shape brings other implications. In our complex world there are clues about the direction of time, but physicists ask – ‘can we tell for the simplest things?’ If the electron’s shape is an egg, time’s arrow permeates even the tiniest scales. If it is round, then we cannot always be certain if we are moving into the future or the past.
You might wonder why we don’t know the shape of the electron by now. The incredible hardness of this question is due to the smallness of the electron. It is infinitesimally small – an unimaginable ten thousand trillion trillion make the weight of a gnat’s wing or a single snowflake. So an electron is affected by everything and we have to pay attention to many details.
Here is our experiment, beautiful with its simple question, economy and far reaching meaning, requiring so much ingenuity and paraphernalia.
In the subterranean room, beneath the weight of twelve storeys, the systems hum. Spending time with the experiment, you lose track of the hours and the weather. The laser light speckle is steely and captivating and hard on the eyes. There’s a tall chamber shielded in magnetic field proof jackets. Inside it’s as cold as space. The electrons travel upwards in synchronisation – spinning and precessing. Preparations and measurements are made with the finely tuned green laser beam light causing the electrons to sing and give up information. An egg shape precesses faster than a round one - the experiment measures how fast the electrons precess.
The close knit little band of scientists working on the experiment is dogged, clever, dry humoured, war torn, serious and beautiful. They have had some quease-making setbacks over the years. They never stop trying to figure out problems. It is like an almost infinite crossword puzzle. After so long, one can read the health of the laser light from its colour and intensity, intuit if the calculating machines are working well and spot if there is something out of place. He says the work requires great pessimism, so every small advance feels like progress. To save themselves from bias inherent in their human nature they mask the results and take the data blind. And they take vast quantities.
So far, the electron remains stubbornly round. And over dinner friends say “of course it is - what have you been wasting your time doing?” They don’t realise they might not be here if it was and that time’s arrow may sometimes be unknowable.
The experiment is measuring with staggering accuracy to a hairs breadth against the size of our galaxy. Teams in America are entering the fray and everyone will be glad if someone delivers a result. Our experimenters will make the experiment much more precise and keep measuring even if they have to build a new machine, looking for the tiny asymmetry.