In 2013, physicists in Munich put potassium atoms at a negative absolute temperature, a few billionths of a kelvin below zero. They were not colder than absolute zero, quite the opposite. In this state, most atoms sit in the highest energy levels available. Placed against any ordinary object, this gas would give up its heat: in a sense, it is hotter than infinity.
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.