Accessibility statement

New breakthrough discovery: Every quantum particle travels backwards

Posted on 17 July 2017

Mathematicians at the Universities of York, Munich and Cardiff have identified a unique property of quantum mechanical particles – they can move in the opposite way to the direction in which they are being pushed.

In everyday life, objects travel in the same direction as their momentum – a car in forward motion is going forwards, and certainly not backwards.

However, this is no longer true on microscopic scales - quantum particles can partially go into reverse and travel in the direction opposite to their momentum. This unique property is known as ‘backflow’.

Dr Henning Bostelmann, from the Department of Mathematics, was one of the researchers involved in this discovery.  Further information is on the University news page.

Quantum backflow and scattering by Dr Henning Bostelmann (University of York), Daniela Cadamuro (TU Munich) and Gandalf Lechner (Cardiff University) is published in Physical Review A. To read, visit: This research was supported by a LMS Research in Pairs grant, Ref. 41607.