In 1922, Otto Stern and Walther Gerlach sent silver atoms through a magnetic field. As Stern told it, the deposit on the plate was at first too thin to see… until his breath, laden with sulfur from a cheap cigar, blackened it into silver sulfide. Two distinct spots revealed that some atomic properties can only take specific, separate values.
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.