The secrets of spin – and it’s not cricket!

A quantum mechanics expert at the University has unlocked the secret of why electrons have a mysterious property called ‘spin’.

Professor Paul Strange, of the University’s School of Physical Science, has developed a new and unique perspective on the way particles move.

All fundamental particles, e.g. electrons, have a mysterious property called spin. Although it has many of the properties of rotation, it isn’t the same type of spin as that of a child’s toy spinning top.

In research published by the American Physical Society, Professor Strange found that individual components of particles rotate at different rates.

Because of this, he found that theoretically there is no speed at which an observer can ‘rotate’ where the particle will appear stationary. Furthermore the rotation of an observer affects how they would see the particle in two ways.

Firstly, there is the usual mechanical rotation which can be compared to the Earth orbiting the Sun. Although the Earth moves round the sun, on Earth we see the sun going round us.

Secondly, and unexpectedly, the observer’s rotation changes the probability of an observer measuring the spin as being clockwise or anticlockwise.

The paper, entitled Angular momentum of a relativistic wave packet, is published in the journal Physical Review A.