Where in physics does randomness occur?

[Jarfi]

Electrons appear randomly in quantum physics, but are there any other places where particles behave randomly, is there any other true randomness in the universe, something we can not predict?

 

[phyzguy]

How about radioactive decay? A uranium nucleus happily sits there for a billion years, then one day emits and alpha particle and decays. Why? There is no known reason.