[AndrewC]

In thermodynamics, a spontaneous process in one that happens in a finite time under the existing conditions.

Well, that definition is equivalent to "what happens, happens". The dictionary defintion of spontaneous includes "Happening or arising without apparent external cause; self-generated. ". Now what happens to the surroundings of a closed system due to the events within the closed system? Nothing. It is a closed system.

[Right Wing Professor]

Well, that definition is equivalent to "what happens, happens". The dictionary defintion of spontaneous includes "Happening or arising without apparent external cause; self-generated. ".

Thermodynamics uses a specific technical definition of 'spontaneous' which is not the same as the conventional definition. If you want to discuss thermo., learn the jargon.

Now what happens to the surroundings of a closed system due to the events within the closed system? Nothing. It is a closed system.

Heat can leave a closed system. What you apparently mean is an adiabatic system. Once again, if you want to discuss thermo., learn the jargon.