People are interested in easy and real levitation methodology as well as its applicability to every type of objects including human- Dr SS Verma

Levitation is a phenomenon of making any kind of object (including human) to float in air for small to large distances with short and long time intervals and has always fascinated human and its achievability has been studied both spiritually and scientifically. The latest hit "Harry Potter" films are making children crazy with levitating human to objects with different methods. Spiritually developed levitation in that way is supposed to be more powerful as it is not limited to type of objects and is cost-free. A spiritual person can levitate himself as well as other objects also for as much distance and time as the power of spiritualism allows. Scientifically, levitation is looked from the angle of defying gravity, a force which always attracts everybody towards the centre of earth, but without any success so far. However, with the development of magnetic levitation, a method by which an object is suspended above another object with no support other than magnetic fields and where the electromagnetic force is used to counteract the effects of the gravitational force, it has been extensively studied and even superconducting levitating trains are being developed. In this technology a magnetic substance is repelled (gets levitated) when placed on a superconductor which itself behaves as a perfect dia-magnet and completely expels magnetic field at low temperatures. So far this technology is however limited to metals and that also under the condition of superconducting state. Normal things, even humans, can do it as well, if placed in a strong magnetic field. People are interested in easy and real levitation methodology as well as its applicability to every type of objects including human.

When the levitation of big objects is proving to be difficult and also the world is turning towards micro objects & machines using nanotechnology, scientists have discovered a ground-breaking way of making tiny objects levitate by reversing a mysterious force "Casmir" of nature, which may revolutionize the design of micro-machines. Physicists said they can create "incredible levitation effects" by manipulating so-called Casimir force, which normally causes objects to stick together by quantum force. Now the UK scientists say they can reverse the Casimir force to cause an object to repel rather than attract another in a vacuum. The Casimir force is the attractive force between two surfaces in a vacuum - first predicted by Hendrik Casimir in 1948 and first measured in 1997 - can be seen in a gecko's ability to stick to a surface with just one toe and could affect everything from micro-machines to unified theories of nature. The Casimir force is the ultimate cause of friction in the nano-world, in particular in some micro-electromechanical systems.

In the old days of classical mechanics the idea of a vacuum was simple. The vacuum was what remained if you emptied a container of all its particles and lowered the temperature down to absolute zero. The arrival of quantum mechanics, however, completely changed our notion of a vacuum. All fields - in particular electromagnetic fields - have fluctuations. In other words at any given moment their actual value varies around a constant, mean value. Even a perfect vacuum at absolute zero has fluctuating fields known as "vacuum fluctuations", the mean energy of which corresponds to half the energy of a photon. Vacuum fluctuations have observable consequences that can be directly visualized in experiments on a microscopic scale. The Casimir force is the most famous mechanical effect of vacuum fluctuations. It turns out that, on balance, the attractive components have a slightly stronger impact than the repulsive ones. For two perfect, plane, parallel mirrors the Casimir force is therefore attractive and the mirrors are pulled together. The force, F, is proportional to the cross-sectional area, A, of the mirrors and increases 16-fold every time the distance, d, between the mirrors is halved: F ~ A/d4. Apart from these geometrical quantities the force depends only on fundamental values - Planck's constant and the speed of light. Although the Casmir force might appear small, at distances below a micro-metre it becomes the strongest force between two neutral objects. Indeed at separations of 10 nm - about a hundred times the typical size of an atom - the Casimir effect produces the equivalent of 1 atmosphere of pressure.

For many years the Casimir effect was little more than a theoretical curiosity. But interest in the phenomenon has blossomed in recent years. Experimental physicists have realized that the Casimir force affects the workings of micro-machined devices, while advances in instrumentation have enabled the force to be measured with ever-greater accuracy. The new enthusiasm has also been fired by fundamental physics. Many theorists have predicted the existence of "large" extra dimensions in 10- and 11-dimensional unified field theories of the fundamental forces. These dimensions, they say, could modify classical Newtonian gravitation at sub-millimetre distances. Measuring the Casimir effect could therefore help physicists to test the validity of such radical ideas. There are many problems (like absence of vacuum, absolute zero temperature and smoothness of surfaces) being associated with the exact calculation of Casimir force for a real system. It is the fact that experiments are never carried out at absolute zero which causes thermal - as well as vacuum - fluctuations to come into play. These thermal fluctuations can produce their own radiation pressure and create a bigger Casimir force than expected. While roughness is invisible to the naked eye, it does affect measurements of the Casimir force, which is very sensitive to small changes in distance.

On the micron and submicron scale, the Casimir force can cause the tiny elements in a device to stick together but the force can also be put to good use. Although we do not deal directly with such small distances in our everyday lives, they are important in nano-scale structures and micro-electro-mechanical systems (MEMS) which are "intelligent" micron-sized devices in which mechanical elements and moving parts, such as tiny sensors and actuators, are carved into a silicon substrate. Scientists have demonstrated how the force can be used to control the mechanical motion of a MEMS device. The phenomenon could be used to improve the performances of everyday devices ranging from car airbags to computer chips. Micro or nano-machines could run smoother and with less or no friction at all if one can manipulate the Casmiri force. In order to reduce friction in the nano-world, turning nature's stickiness into repulsion could be the ultimate remedy. Instead of sticking together, parts of micro-machinery would levitate. At the moment, in practice 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. But it is stressed that in principle it may one day be possible to levitate humans which so far now remain the subject of cartoons, fairytales and tales of the paranormal.

Dept of Physics, SLIET, Longowal

The article above was found on Google and was published originally on Central Chronicle