If you were to walk into the Swiss Federal Institute of Technology in Switzerland, you might need to stop, rub your eyes, and do a double-take. Why?
Because you’d see sights like this…
Hovering toothpicks, flying coffee beans—and yes, dancing water droplets that float upward!
And while you wouldn’t be greeted by a bunch of scientists sitting around in a circle chanting “Ohm Ohm on the Range” you would meet the researchers who have found a new way to manipulate objects in midair by using sound waves.
Now, before we go any further, we’re not talking about other forms of levitation that various scientists have delved into over the years. Believe it or not, levitation itself isn’t a new field of research, and experiments have been ongoing since the beginning of the 20th Century.
For example, in 1909, Dr. Robert Millikan and Dr. Harvey Fletcher of the University of Chicago managed to levitate charged droplets of oil in an electrical field as they conducted experiments measuring the charge of an electron.
Likewise, Doctors Arthur Ashkin and Joseph Dziedzic were successful in using a laser to optically levitate glass particles at Bell Laboratories, USA, in 1971.
And in 1997 Dr. Andre Geim managed to levitate a live frog within a magnetic field at Radboud University, Nijmegen, Netherlands, and actually went on to win a Nobel Prize for his effort in this field.
As encouraging as research in these areas were, development was quite restricted. Electrical systems have to be charged. Optical systems have to be transparent. And in magnetic systems, the object being levitated has to have magnetic properties.
The wonderful thing about the latest breakthroughs in acoustic systems is that they have a much wider application. Let’s take a look at a brief history.
Acoustic levitation was invented by NASA in the 1980’s to simulate microgravity conditions. The trouble was, scientists could only hold a single object in place or rotate it on the spot. That would now appear to be a thing of the past.
Researchers in Switzerland have discovered how to actually move more than one object through the air. Basically, the system they devised incorporates the use of vibrating square platforms, each of which is the size of a thumbnail. The platforms send out sound waves and reflect them off a surface above. At certain frequencies, the reflected signals combine with the upward-moving ones to create a pattern known as a Standing Wave.
The Standing Wave has areas within in which stay fixed, even as the ripples about it continue to oscillate. If an object is placed at one of these fixed-points, it will float, as the pull of gravity is balanced by the upward moving impulse.
By lining up a series of platforms, and then varying the sequence of the oscillations from one to the next, researchers are able to place a toothpick in midair, and carry it from one end of a grid to another.
To generate enough lift, the system had to emit sound waves at the same volume as a jet engine, 160 decibels. So, researchers employed ultrasonic waves with a frequency of 24,000Hz which is too high for a human to hear.
So, it won’t be long before we see a man floating through the air, yes?
Ah, there’s the rub. If you wanted to levitate a human being using the current model, scientists would have to drastically increase the wavelength and decrease the sound frequency. That would make the sound waves audible and very painful. Also, because extremely high sound power levels would be required, we can only imagine the damage this might cause to the human body itself.
So, floating about in your own living room is still a way off…But we’ve taken a step in the right direction, because researchers are already looking into ways the current method could be used to move radioactive and other hazardous chemicals without having to touch them. Good news indeed.
And of course, as things advance, other exciting applications might come our way sooner than expected, especially in the areas of transport, health, and leisure.
Whatever floats your boat…Life’s sure to get interesting.
Until then. Stay safe, I’ll catch up with you soon.