quantum physics!
Believe or Not. Its a common sence.
Look around your life.
Ex: Look at the dice.
When you throw once,you cant know what number you see.
But 10000000000times throwing, you will see the tendency!
Thats call,the (Heisenberg) uncertainty principle
Small Particular act same.
Each human act different... But 10000000000000people?
Foton act the same....