The lab notebooks Marie and Pierre Curie filled in the late 1890s remain contaminated with the radium they handled without today's protections. Radium-226 takes about 1,600 years to lose half its radioactivity. Kept at the National Library of France in lead-lined boxes, they can only be consulted under special precautions, a century after the ink dried.
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.