Circus trick: Casimir force along with the van der Waals force is what allows geckos to hang upside down from a single toe.
Credit: National Science Foundation/ Kellar Autumn
SYDNEY: Theoretical physicists have discovered a previously unknown method of levitating small objects, and it may revolutionise the design of nanomachines.
The British scientists said yesterday that they had completed calculations which suggest "incredible levitation effects" by manipulating so-called Casimir force, which normally causes objects to stick together by quantum force.
Weird quantum effect
The phenomenon might be used to improve the performances of everyday devices ranging from tiny gadgets that trigger the inflation of car airbags to miniature labs-on-a-chip becoming increasingly popular in genetics and drug testing, said Ulf Leonhardt and Thomas Philbin from the University of Saint Andrews in Scotland.
Casimir force, a weird quantum effect discovered in 1948 and first measured in 1997, can be seen in a gecko's ability to stick to a surface with just one toe.
Now the physicists say they can reverse the Casimir force with a lens made of a new type of 'metamaterial' with a negative refractive index (meaning it bends light in the opposite direction to normal material), to cause small objects to repel rather than attract one another in a vacuum.
They believe the force would be strong enough to levitate an aluminium mirror that is 500 nanometres thick.
"The Casimir force is the ultimate cause of friction in the nanoworld, in particular in some micro-electromechanical systems," wrote the Leonhardt and Philbin in the August issue of the open access publication New Journal of Physics.
"Micro- or nanomachines could run smoother and with less or no friction at all if one can manipulate the force," said Leonhardt. "In order to reduce friction in the nanoworld, turning nature's stickiness into repulsion could be the ultimate remedy. Instead of sticking together, parts of micromachinery would levitate."
Still mostly theoretical
However, the technology behind creating suitable metamaterial lenses is still mostly theoretical, physicist Federico Capasso of Harvard University in Cambridge, U.S., told the British magazine Physics World. "The work points towards new applications of left-handed materials that are not strictly optical," he commented. "However, the materials are not easy to make so the concept may take a few years to realise."
Leonhardt stressed that even then, the practise will be possible only for miniscule objects.
He also underlined that, although in principle it may one day be possible to levitate humans, that day is a long way off.
"It is only going to be possible for micro-objects with the current technology, since this quantum force is small and acts only at short ranges," he said. "For now, human levitation remains the subject of cartoons, fairytales and tales of the paranormal."
with AFP
