In 1924, Louis de Broglie defended a bold thesis: if light is both a wave and a particle, why not electrons too? Unsure what to make of it, his supervisor Paul Langevin sent a copy to Einstein, who warmly endorsed it. Electron diffraction confirmed the idea in 1927, earning de Broglie the 1929 Nobel Prize in Physics.
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.