Can the way the universe behaves at the tiniest scales be recreated in the laboratory?
Physicist Igor Smolyaninov of the University of Maryland in College Park has a recipe for cooking up a lab-scale version of a 鈥渜uantum foam鈥�, the choppy substance that constitutes space-time in some theories of quantum gravity.
According to these theories, space-time may appear smooth and curved, but zoom in, and it is actually made of virtual black holes, each just 10-35 metres wide, which flit in and out of existence.
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To mimic this structure, Smolyaninov suggests exploiting 鈥渃ritical opalescence鈥�. At certain temperatures, some combinations of fluids can roil and form a rough mixture of separate patches. As photons travel at different speeds through each fluid, light is refracted, or bent, at the boundaries between the patches and the mixture ends up opaque.
Transient patches
Immersing a mesh of metal wires into such a mixture accentuates these speed differences. Smolyaninov calculates that the differences could be made so great that incoming light would bounce repeatedly around the interior of the patches, . Dependent on fluctuations in heat, such 鈥渂lack holes鈥� would be transient like those in a quantum foam.
It鈥檚 not clear what this artificial foam could tell us about quantum gravity, but Smolyaninov says that, at the very least, it could allow physicists to 鈥渁sk more intelligent questions about how to detect the real thing鈥�.
Materials with properties that are engineered by manipulating their structure, rather than their chemical composition, are known as metamaterials. Previously, these have been used to create longer-lived, artificial black holes, which might be used to harvest solar energy, as well as invisibility cloaks.
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