“Crowd sourcing” to play a key role in fundamental physics experiment

Cern accelerators
Cern accelerators (Photo credit: Cédric.)

Ordinary people are to be asked to make a contribution to an experiment which aims to determine key facts about the nature of the physical universe – reports the New Scientist.

Particle physicists at CERN – the join European experiment famous for the Large Hadron Collider – are conducting an experiment – AEgIS – into whether anti-matter interacts with the gravitational field in the same way as matter.

Most of our universe seems to be made of matter – a mystery in itself because there is no simple explanation why ‘matter’ should outnumber ‘anti-matter’ – and the two forms annihilate one another in a burst of energy when they meet – so it can be difficult to conduct experiments with anti-matter.

Anti-matter particles pair up with matter – so for the electron, the negatively charged particle in our everyday atoms, there is an anti-matter positron, which is a positively charged particle which looks like an electron except it appears to ‘go backwards’ in quantum physics experiments (i.e. if we show an electron carrying negative charge in one direction, we can show a positron going in the opposite direction – and backwards in time! – with out violating physics’ fundamental laws). Richard Feynman’s brilliant QED – The Strange Theory of Light and Matter is strongly recommended if you want to know more about that.

Conventionally it is assumed gravity interacts with matter and ant-matter in the same way, but in reality our deep physical understanding of gravity is poor. For while Einstein’s general relativity theory – which describes gravity’s impact and has stood up to every test thrown at it – is widely seen as one of the great triumphs of 20th century physics, it is also fundamentally incompatible with how other “field” theories (like that for electricity) work and as a force is much. much weaker than the other fundamental forces – all of which suggest there is a deeper explanation waiting to be found for gravity’s behaviour.

Showing that anti-matter interacted with the gravitational field in a different way from matter could open up huge new theoretical possibilities. Similarly, showing anti-matter and matter were gravitationally equivalent would help narrow down the holes in our theoretical understanding of gravity.

How can the public help? Well, on 16 August (just after the New Scientist article was printed) CERN asked for the public’s help in tracing the tracks made by particles in experiments: these tracks are then analysed to judge how gravity impacted on the particles (some of which will be anti-matter).

The public can help CERN analyse many more tracks and – crucially – help calibrate CERN’s computer analysis software.

It is expected that there will be further requests for help – so it might be worth keeping your eyes on the AEgIS site if you are interested in helping. (The tutorials are still up. but all the current tasks have been completed).



Seems neutrinos do not arrive before they leave after all

English: The first use of a hydrogen bubble ch...
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It would appear, reports Science magazine, that neutrinos may not travel faster than light after all – a finding from CERN’s OPERA experiment that would mean, assuming that every other aspect of relativity was not broken, that either neutrinos arrive at a destination before they leave a source or that they cross the universe via some other dimensions than our world of spacetime.

It is now suggested that a faulty connection with a GPS transceiver

may have skewed the results.

If it wasn’t for those pesky neutrinos

Reactions in the proton-proton chain. The % va...
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Neutrinos have proved to be nothing but trouble for scientists over the years.

They could not detect them from the Sun (where they are produced as a by-product of fusion), then they did or did not have mass. Now, it seems, they travel faster than light and are threatening to overturn the apple cart of relativistic space-time. If my dimly recalled understanding of relativity is correct, this would imply that, from the netrino’s point of view, it travels in the opposite direction to the way we see it moving in our reference frame: plainly, either the experiment is giving the wrong results or our theory of space-time is very seriously flawed.

Of course, what these troubles mean is that neutrinos have been huge allies in our search for a better understanding of physical reality. Though this new finding – which has plainly caused consternation amongst those who have been conducting the experiment – would be truly shocking if confirmed.

Earth surrounded by a ring of anti-protons

earth magnetic field
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The “solar weather forecast” for the next few years is for increasingly poor conditions – as the solar cycle picks up, more matter will fly out from the Sun and eventually collide with our planet’s magnetic field, where the trapped high energy particles will then lose energy by radiation, so potentially disrupting many of our communications systems.

The solar particles, though, are not responsible for everything trapped by the Earth’s magnetic field – cosmic rays provide much higher energy particles than anything that comes out of the Sun and, it seems, also fuel a belt of trapped anti-protons around the Earth (as reported in this week’s New Scientist).

Anti-matter – which mutually self-destructs on contact with matter is a fascinating subject: working out why there is so little of it (when physics suggests there should be equal quantities of it and matter) is at the heart of cosmologists attempts to explain the creation of the universe.

So far the only way to access it consistently has been produce it in high energy collisions in places like CERN. The fact that the Earth has several billion anti-protons spiralling around it’s magnetic field at any given time, may, therefore point to new ways for researchers to get at it without having to build ever bigger colliders – though obviously space satellites aren’t ten-pence-a-dozen either.