The Meissner effect is responsible for the incredible ability of superconductors to levitate above magnets – or indeed for magnets to levitate above superconductors.
Read more: “Instant Expert: Superconductors”
Exactly 100 years ago, a Dutch physicist called Heike Kamerlingh Onnes and his team made a remarkable and completely unexpected discovery. They found that certain metals completely lose their electrical resistance when cooled to within a few degrees of absolute zero. A coil of wire made from such a metal could carry an electrical current round and round forever, without needing a power source to drive the current. No one had predicted this phenomenon and at the time no one could explain it. The effect was named superconductivity – the prefix “super” implying that it was in a completely different league from anything seen before. It took more than half a century to figure out how superconductivity might work and how to make it useful. More recently, though, we have come to realise that we understand the phenomenon far less well than we thought.
The big discovery
Heike Kamerlingh Onnes spent most of his scientific career in the quest to achieve the lowest temperatures possible. His big breakthrough came in 1908 when he managed to make liquid helium, the last of the gases to be liquefied because it requires temperatures as low as 4 degrees above absolute zero – the lowest possible temperature, equivalent to 0 kelvin or -273.15 °C.
Kamerlingh Onnes was one of the first people to really understand that advances in low-temperature physics critically depended on having first-rate technicians, expert glassblowers and skilled craftspeople to build and maintain the delicate equipment. …
