From afar, lightning looks broad and dazzling. Yet the channel carrying the current is only a few centimetres across, sometimes less, over kilometres of length. Tens of thousands of amps flow through this tiny tube. This thin channel of superheated air glows so intensely that it dazzles the eye, making the bolt look far thicker than it really is.
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.