A 10,000-volt static spark does nothing to you, while a household socket can be deadly. The difference lies in how much current flows through your body, and for how long. A few tens of milliamps crossing the heart for a fraction of a second can trigger fibrillation. Voltage matters because it drives that current through your skin's resistance.
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.