Electrons are almost perfectly round, scientists discover

By Murray Wardrop

Researchers at Imperial College London have made the most accurate measurement yet of the shape of an electron, finding that it is almost a perfect sphere.

Experts found that the subatomic particles differ from being perfectly round by less than 0.000000000000000000000000001cm.

In layman’s terms, this means that if an electron was magnified to the size of the solar system, it would still appear spherical to within the width of a human hair.

Physicists from the university’s Centre for Cold Matter studied electrons inside molecules called ytterbium fluoride.

Using a laser, they made measurements of the motion of these electrons, looking for any distinctive wobbles which would suggest that the shape of the molecule was distorted – as would occur if the electrons were not perfectly round.

The team observed no such imperfections during experiments spanning more than a decade.

The results are important in the study of antimatter, an elusive substance that behaves in the same way as ordinary matter, except that it has an opposite electrical charge.

For example, the antimatter version of the negatively charged electron is the positively charged anti-electron, known as a positron.

Understanding the shape of the electron could help researchers understand how positrons behave and how antimatter and matter differ.

Dr Jony Hudson, from the Department of Physics at Imperial College London, said: "We're really pleased that we've been able to improve our knowledge of one of the basic building blocks of matter.

“It's been a very difficult measurement to make, but this knowledge will let us improve our theories of fundamental physics.

“People are often surprised to hear that our theories of physics aren't ‘finished’, but in truth they get constantly refined and improved by making ever more accurate measurements like this one.”

The Big Bang created as much antimatter as ordinary matter, according to the currently accepted laws of physics.

However, antimatter has only been found in minute amounts from sources such as cosmic rays and some radioactive substances since the concept was conceived by Nobel Prize-winning scientist Paul Dirac in 1928.

Imperial's Centre for Cold Matter aims to explain this lack of antimatter by searching for tiny differences between the behaviour of matter and antimatter, which have so far not been observed.

Had the researchers found that electrons are not round it would have provided proof that the behaviour of antimatter and matter differ more than physicists previously thought.

This, they say, could explain how all the antimatter disappeared from the universe, leaving only ordinary matter.

Professor Edward Hinds, research co-author and head of the Centre for Cold Matter at Imperial College London, said: "The whole world is made almost entirely of normal matter, with only tiny traces of antimatter.

“Astronomers have looked right to the edge of the visible universe and even then they see just matter, no great stashes of antimatter.

"Physicists just do not know what happened to all the antimatter, but this research can help us to confirm or rule out some of the possible explanations." The research is published in the journal Nature. Telegraph