After an experiment with a frog levitating inside a magnetic field won its author, Russian physicist Andrei Geim, the IgNobel prize by thanks to his unimpressed colleagues, researchers keep coming up with ever newer new ways of defying the Earth’s gravity.
Force of Sound
No object can possibly be suspended midair all by itself – there is always something that keeps it afloat. Like, for example, the sound waves a team of British researchers have been experimented with.
Making 2mm three-dimensional metamaterial bricks, each encoding a specific phase delay, they assembled them in a snake-like pattern to generate a diffraction-limited acoustic field.
Placing the bricks in two arrays so that the generated 40 megahertz acoustic wave, inaudible to the human ear, focused at the center, they managed to suspend a small ball in the air for a limited period of time.
Chugging or Flying?
The principle of levitation has found its best-known application in high-speed superconductor trains. The wheels of conventional railway cars touch the rails and, therefore, any small bump or emergency break can damage both the wheels and the rails.
However, this isn't the case with so-called levitating trains or maglevs. They use two sets of magnets, one set to repel and push the train up off the track as in levitation (hence Maglev, Magnetic-levitation), then another set to move the “floating train” ahead at great speed taking advantage of no friction.
With Maglev technology, there are no moving parts. The train travels along a guideway of magnets which control the train's stability and speed.
The magnetic field in the train is produced by superconducting electromagnets. The repulsive force in the track is created by an induced magnetic field in wires or other conducting strips in the track.
Characters in sci-fi movies are often seen using virtual touchpads floating in the air or deployed out of a tiny box. No such technology is available today, but scientists are working on this.
A team of researchers in Canada has pitched the idea of drawing pictures in the air with the help of quadcopters flying synchronously and able to mimic human movements.
By responding to the operator’s hand movements, the drones can draw the image of, say, someone he or she is talking to via a video link.
Even though drones the size of a human palm remain things of the future, the authors hope to scale them down to at least 1 centimeter across.