I don't mean to sound argumentative, but it isn't a theory...it's just a fact. There are loads of pages written specifically by developers and programmers, as well as researchers, and though they don't readily like to talk about it, but by the casinos themselves when forced to confront it. It's one of those 'it simply is' kinds of things. I know it may spoil the thrill for some who 'feel' they've gotten lucky by stopping the reels, but it's one of those things casinos love, because there's the 'supposed' uncertainty aspect of it all, because you never ever get to see the 'but what if' outcome by NOT having stopped it on that given spin.
But that's how it is. Casino slots work on computer programmes and algorhythms and random number generators. And while the outcome is definately set by the player (not the odds of course or max payout) by SPINNING the reels (because while millions of possible outcomes are speeding by at nanoseconds, and you determine which one you get by hitting spin) the outcome is in NO WAY affected by hitting STOP; that aspect was determined the second you hit spin and the programme stopped on the potential outcome
You can debate it and believe otherwise; the casino banks on it and loves you for it, but anyone who actually designs the programme can tell you otherwise