fourmilab.ch

E1A10 TIL Gold's yellow color and inertness are explained by Einstein’s theory of relativity. Gold's electrons travel so close to the speed of light that relativity contracts some of their orbits. This shrinks an energy gap so it absorbs blue light, and makes the outer electron less reactive.
d848Q TIL that the gun on the A10 Warthog fighter plane produces so much recoil that, if you pointed backwards and never ran out of ammo, you could use it to fly.
rrxM TIL that Bismuth has a half life a billion times longer than the universe