In 1911, Heike Kamerlingh Onnes cooled mercury to about −269 °C and its electrical resistance vanished completely. A current started in a superconducting ring keeps circulating with no battery and no measurable loss. Experiments have kept one going for years. The same effect powers the magnets in MRI scanners, which sit bathed in liquid helium.
Cooled below −183 °C, oxygen turns into a pale blue liquid. Pour it between the poles of a strong magnet and, instead of flowing away, it hangs suspended between them. The reason lies in its unpaired electrons, which respond to the magnetic field. Liquid nitrogen, by contrast, is colourless and pours straight through.
In 2012, Felix Baumgartner jumped from a capsule hanging beneath a balloon, about 39 kilometres up. In that extremely thin air almost nothing slowed him down, and he reached around 1,358 km/h in free fall, or Mach 1.25. He became the first person to exceed the speed of sound with nothing but his own body.