Scientists create real sonic screwdriver -

Scientists have finally worked out how to build Dr Who's sonic screwdriver.

Everyone knows that with one of these tools you can bring down the world's largest galactic empires, when you are not spending your time running down corridors.

OK, the technology is not quite there yet. The Dundee University researchers have created a machine which uses ultrasound to lift and rotate a rubber disc floating in a cylinder of water.

But it is the first time ultrasound waves have been used to turn objects rather than simply push them.

According to the BBC, the Dundee researchers are not really interested in galactic domination either.

They think that it will make surgery using ultrasound techniques more precise, the physicists said.

In some ways it will go for a tool which can allow surgeons to treat a range of conditions without having to cut open a patient.

Strangely the Doctor has never actually operated with his sonic screwdriver, although he has used them for medical scans. But the ability to steer ultrasound waves to the precise spot where they are needed could make those treatments even more effective.

One of the researchers, Dr Mike MacDonald, used energy from an ultrasound array to form a beam that can both carry momentum to push away an object in its path and, by using a beam shaped like a helix or vortex, cause the object to rotate.

All that had to be done then was to reverse the polarity of the neutron flow, and your father's brother's name was Robert.