In the 18th century, Benjamin Franklin had to pick, arbitrarily, which charge to call positive. More than a century later, it turned out that what moves in wires is electrons, and they are negative. They therefore flow opposite to the current drawn in circuit diagrams. Physicists kept the convention anyway: rewriting every textbook would have been worse.
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.