Send a stream of silver atoms (each acts like a magnetic needle, in a sense), through a strong North South magnet. What do you expect classically?

Energy to knock an atom out

Consider a Helium Atom with it’s two outer electrons. To knock an electron, one needs a very specific, exact amount of energy (corresponding to a laser wavelength of 50 nm). If you deviate even 0.0000001 % from this wavelength, the electron will not be knocked out. Classically – say you have to knock pluto out of it’s orbit. Whether you hit it with a small missile, a medium missile or a large missile – each missile will have some effect on the orbit. The larger the missile, the greater the effect. Not so in QM. Only the EXACT size missile will work.

The Probability Wave (Wave Function) – Is it real or not?

In some cases, it is an actual real wave!