Engineers at the 846th Test Squadron simply shattered the Maglev record with a sled powered by a very powerful rocket. The sled raced through a magnetic levitation track at an incredible 633 mph, or 120 mph faster than the previous record which they set only two days before.
Maglev trains are very fast, and quite popular in Japan where they have a high-speed rail of this sort set up that can reach top speeds of 373mph. Instead of using wheels on a track, Maglev trains floats above the track on a magnetic cushion. There's no friction, so Maglev transportation can be very efficient and low maintenance.
The contraption made by the U.S. Air Force uses very powerful electromagnets to keep itself afloat, but in order for them to work these need to be cooled with liquid helium to about four degrees Kelvin. That's only four degrees above the absolute coldest, or roughly equal to -270 degrees Celsius. It was then only a matter of strapping a really powerful rocket and let it zip on a 2,100 foot-long track.
The electrical resistance of an object depends on its temperature and declines slowly as the temperature falls. For almost a century, scientists have known that if you cool a metal close to absolute zero then the material loses almost all traces of electrical resistance. This effect is called superconductivity. Much later in the '60s, the first superconducting coils were made which permit the construction of extremely powerful electromagnets. By having magnets both on the tracks and on a train, you achieve levitation -- enough to support hundreds of tons at a ferocious speed.
The Air Force's record means that a similar Maglev train could travel from New York to Los Angeles in only four hours. Traveling this fast is a waste of energy as it's inefficient for a Maglev system. The acceleration might also cause a few to faint, so for now Elon Musk's Hyperloop looks sweeter. Research like this where technology is being pushed to the limits will help unravel fundamental secrets in Maglev systems and make trains or other transportation devices faster, more reliable and safer.
Next, the team plans on refining the design to go even faster.