It is said that almost all phenomena are dependent on cause and effect. There is assumed to be a chain of cause and effect ,leading the philosophers and scientist to believe that there must have been a first cause.
However spontaneous phenomena do not require any previous cause and scientifically we say that such a phenomena is driven by the laws of probability. For example - radioactivityradioactivity
My question is : What are some examples of spontaneous phenomena other than radioactivity?