(Edited) What is the noun for ''the way of thinking about what could have happened in the past all the time'' [closed]

in short the noun defines 'thinking and talking about what ifs a lot'

Edit: Unfortunately none of the answers came with the word i'm looking for and I'm sorry I was not fully prepared when I first asked the question.

Context:

Counterfactual history uses hypothetical thought-experiments to imagine the probable results of changes in the historical record. The hypotheses are two-part conditional statements, consisting of an ‘if’ and a ‘then’ clause: if the Luftwaffe had won the air battle, then the Germans might have successfully invaded Britain. Military historians have used counterfactual analysis for centuries. Among professional historians, they are still the most consistent practitioners.

So now the question is 'what could we call those particular military historians?' Bear in mind that they do the counterfactual analysis excessively.

As for the 'thinking about what could have happened in the past all the time' part, I think retrospection fits quite nicely:

retrospection

NOUN

the act of thinking now about something in the past

Examples:

He is a man of action, not retrospection.

(Cambridge Dictionary)

However, I think speculation captures 'thinking and talking about what ifs a lot' better:

speculation

NOUN

ideas or guesses about something that is not known

(Merriam Webster)

Speculation might refer to the past, the present, or the future, though. If you meant 'the act of living in the past', then retrospection is a better choice, I guess.