Quantum friction: does it exist after all?

Edwin Cartlidge in Physics World:

For several decades physicists have been intrigued by the idea of quantum friction — that two objects moving past each other experience a friction–like lateral force that arises from quantum fluctuations in the vacuum.

Several independent groups of physicists have previously calculated that quantum friction could arise from the Casimir force between two plates — when those plates move relative to one another. There is also some indirect experimental evidence that such a lateral force exists.

Now, however, researchers in the UK having performed detailed calculations, which they claim show that there is no lateral force and that quantum friction therefore doesn’t exist.

In 1948 Dutch physicist Hendrik Casimir worked out that two uncharged, perfectly conducting metal plates placed in a vacuum should be attracted to one another. This force arises from the fact that, according to quantum mechanics, the energy of an electromagnetic field in a vacuum is not zero but continuously fluctuates around a certain mean value, known as the “zero–point energy”. Casimir showed that the radiation pressure of the field outside the plates will tend to be slightly greater than that between the plates and therefore the plates will experience an attractive force.