Unruh effect can be tested in lab, new breakthrough paves way

Researchers have made headway towards lab based testing of one of the cutting-edge theories in fundamental physics – the Unruh effect.

When astronauts in a spacecraft undergo super strong acceleration and see the light of stars stream by, then the Unruh effect is an additional warm glow on top of the streaming light. First predicted by Canadian physicist Bill Unruh, this effect is closely related to the glow from black holes predicted by Stephen Hawking. This is because black holes strongly accelerate everything towards them.

Black holes may be thought of being entirely black, but they aren’t according to researchers. According to discovery made by Stephen Hawking, black holes should emit radiation and this is primarily because while nothing else can escape a black hole quantum fluctuations of radiation can.

Similar to how the Hawking effect needs a black hole, the Unruh effect requires enormous accelerations to produce a significant glow. The Unruh effect was therefore thought to be so weak that it would be impossible to measure with the accelerations that can be achieved in experiments with current technology.

The research team found an innovative way to experiment on the Unruh effect through a novel use of high-intensity lasers. They discovered that shining a high-intensity laser on an accelerated particle can amplify the Unruh effect so much that it actually becomes measurable.

In an unexpected twist, the team also discovered that by delicately balancing acceleration and deceleration, one should even be able to make accelerated matter transparent.

The ability to experiment on the Unruh effect as well as on the new phenomenon of acceleration-induced transparency provide a big boost for physicists, who have long been searching for ways to unify Einstein’s theory of general relativity with quantum mechanics.