In 1930, Wolfgang Pauli wrote to colleagues, addressing them as "dear radioactive ladies and gentlemen," to rescue energy conservation in radioactive decay. He proposed a neutral, almost elusive particle, later named the neutrino. He doubted it could ever be detected. It took until 1956 for Clyde Cowan and Frederick Reines to spot it near a nuclear reactor.
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.