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A View from **Emerging Technology from the arXiv**

## Giant Casimir Effect Predicted Inside Metamaterials

Exotic materials should lead to new ways of observing and playing with one of the strangest effects in physics, say Chinese physicists.

Metamaterials are exotic substances designed to steer electromagnetic waves in ways that are impossible with ordinary stuff. One of their more exciting properties is that they can bend light in a way that is mathematically equivalent to the way spacetime bends light.

This formal equivalence means that metamaterials can reproduce in the lab the exact behaviour of light, not only in our spacetime, but in many others that have only been conjectured until now. This allows physicists to use metamaterials to simulate black holes, big bangs and even multiverses.

Today, Tian-Ming Zhao and Rong-Xin Miao at the University of Science and Technology of China in Hefei use this kind of thinking to make a startling prediction about the Casimir effect inside certain metamaterials.

The Casimir effect arises because our vacuum is filled with a maelstrom of waves that leap in and out of existence at the smallest scales. The best known consequence of this is the well known Casimir force, which pushes together two conducting plates placed close together.

The explanation is that when the distance between the plates is small enough, it can exclude any waves that are too big to fit in the gap. Since there is nothing between the plates to oppose the effect of these waves, they generate a force that pushes the plates together.

This Casimir force operates on a tiny scale, so small that it was only measured for the first time in 1997. But it is not insignificant. At a separation of 10nm, the force is equivalent to 1 atmosphere (although the actual force depends on various factors such as the precise shape of the objects in close proximity).

Of course, the properties of the vacuum waves depend strongly on the medium in which they exist. So it’s not hard to imagine that different spacetimes might have a significant impact on the size of the Casimir effect.

This is exactly what Zhao and Miao show. They say that in a particular kind of electromagnetic space called a Rindler space, the Casimir effect is huge. The essential idea here is that the space can be designed to allow only certain wavelengths to operate. If the electromagnetic properties of the Rindler space are matched to the ambient temperature, then these kinds of thermal waves can be made to dominate the Casimir energy.

That makes the Casimir energy huge. Zhao and Miao calculate that in a lab at 300K (room temperature), the Casimir energy would be some 10^11 times bigger than the free space value. That’s a significant difference that ought to make these effects accessible in an entirely new way to a much broader audience.

Zhao and Miao also say that this kind of material ought to be relatively straightforward to build, layer by layer.

What that means is that it won’t be long before somebody builds this kind of material and shows off the giant Casimir effect for the first time. We’ll be watching.

Ref: arxiv.org/abs/1110.1919: Huge Casimir Effect At Finite Temperature In Electromagnetic Rindler Space