How Tenet happened (at least that is what I think)
So this friend of Nolan was repenting in-front of Nolan that none of the scientific journals are printing his theory on inverted time.
So this guy was best friend of Nolan, so he consoled him saying, let me see what I can do.
Then Nolan called his crew and told them about a new script and that is how Tenet was developed.
Even after this, we only saw half of what was in actual script (thesis paper). I mean its a thesis paper not a script so understandable on the gaps.
I know why the gaps happened too.
It must have happened this way,
Nolan's friend : so with inverted time, this is a problem statement.
To resolve we have to go through step 1 to 10.
Nolan: Ok, that's pretty easy, I believe audience won't need step 1 to 9, keep that for printing your thesis someday. I'll only show problem statement and step 10. Should be enough!