In 1887, Albert Michelson and Edward Morley set out to measure Earth's motion through the "ether," the medium thought to carry light. Their exceptionally precise instrument should have detected a shift depending on its orientation. They found nothing. That null result helped bury the ether and set the stage for Einstein's special relativity in 1905.
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.