Stunning discovery brings sci-fi weapons a step closer

CAPTAIN Kirk's famous command to "set your phasers to stun" could go from science fiction to science fact after a breakthrough discovery to develop lasers capable of harmless paralysis.

In what sounds like the kind of raygun technology of Star Trek, the researchers found a way of firing a laser beam that stuns a living creature.

The beam paralyses the creature and then, when the beam is turned off, it recovers without any ill-effects.

In Star Trek, the crew of the USS Enterprise could set their phaser guns either to kill or merely stun. Now Canadian scientists, reporting in the Journal of the American Chemical Society, believe they have developed a similar system using ultraviolet light.

All animals, including humans, are sensitive to light. Doctors take advantage of this by firing beams into the body to destroy cancer cells, for instance.

However, until now this has not been reversible. The new discovery suggests the body has an on-off switch, so that the effects of light can be reversed in a process known as photoswitching.

The scientists carried out tests on hundreds of tiny worms by feeding them dithienylethene, a light-sensitive chemical compound.

Then they exposed more than 600 of the creatures to ultraviolet light. The transparent worms turned blue and became paralysed.

The beam was turned off and the worms exposed to natural light again. They went from blue back to transparent, and the paralysis ended with most, though not all, surviving the process.