See the frozen puck that appears to be floating in mid-air? Physics is what is holding it there, well magnetic levitation to be exact.
This YouTube video was made by researchers of the Superconductivity Group in the School of Physics and Astronomy at Tel Aviv University in Israel. It has been viewed almost 7 million times since it was posted last October, and it’s not surprising why it’s such a big hit. Who wouldn’t want to watch a puck zoom around a track like it’s floating?
The puck in the video is made of a sapphire wafer coated with a superconductive material known as yttrium barium copper oxide, a ceramic material. The puck was also cooled down using liquid nitrogen because yttrium barium copper acts like a superconductor at -185˚C, meaning it stops magnetic fields from going through it.
So what appears to be a cool magic trick is actually the Messnier effect, a superconducting material repelling magnetic fields in all directions. The track is a set of permanent magnets that create a magnetic field around the superconductive puck. Think of the field as a force that keeps the puck suspended in air because the magnetic field must go around the puck, rather than through it (if it were a normal puck).
Usually a superconductive puck would just float mid-air in a wobbly fashion like a UFO, but the puck in this video appears to be “locked” in place. It can zip around the track on a tilted slant or at a specific height. This is because there are imperfections in the thin superconductive material (it’s only a millionth of a meter thick) and some of the magnetic field can go through the material at these imperfections, locking the puck in place.
So superconductivity looks cool, but what can it be used for you ask?
To build high speed trains.
Shanghai’s Maglev Train, the world’s only commercially operated maglev train when it opened in 2003, can travel at 430 km/h. The technology used in Shanghai’s Maglev Train is a bit more complicated than the superconductivity video; although, it is still based on magnetic levitation using an electromagnetic suspension system.
The train travels above a guideway, and electromagnets are placed on a supporting beam below the guideway. The electromagnets are attracted to the underside of the guideway and create at 15 cm gap between the bottom of the train and the top of the guideway. The train hovers because the magnetic attraction supports the weight of the train. On-board batteries power the electromagnets as well as the train’s electronics.
The Superconductivity Group made the magnetic levitation video as part of their outreach program to educate the general public about superconductivity and what it means. I think this kind of outreach program is fantastic. The researchers use a fun way to demonstrate an interesting phenomenon and also explain the science behind it. This type of outreach may even generate a greater interest in science, which I think would be fantastic.
Good job to the Superconductivity Group for making a cool video to demonstrate superconductivity!
G. Deutscher et al. Quantum Levitation [Online]. Available:
R.W. Hill (2011). Superconducting Levitation Physics in Canada, 67 (2)
Holmer, P. (2003). Faster than a speeding bullet train IEEE Spectrum, 40 (8), 30-34 DOI: 10.1109/MSPEC.2003.1222045