"It imploded right away" explains everything.
"It imploded later" requires at least two failures, first of power/comms, and THEN of the structure itself.
Occam's Razor
"It imploded later" requires at least two failures, first of power/comms, and THEN of the structure itself.
Occam's Razor
is only good as a heuristic for finding which hypothesis to test first.
It's basically a scientist's "where there's smoke there's fire".
It imploded later requires only one failure (the structural failure), just as the relatively short time duration option requires only one failure. Right away is also a later event.
We have no way of knowing what its structural true condition was in terms of whether it was more likely to make it a very short duration or something more like a day.
Wouldn't an implosion be really loud?
As for the banging sounds heard days later, there are a thousand possible sources of those, especially with a dozen or more other vessels on the scene. Anything from a buoy with a loose part clanking away, to some waves breaking and clapping on the surface, to a whale slapping its tail, to extraneous noise from one of the search vessels or its equipment, to other sources of sea life making a racket. It's a bit like trying to listen for the buzzing of a bee in a basketball stadium with a game going on. Any signal you get is far more likely to be something else, but when you have literally no better options, every signal, no matter how unlikely, is worth investigating. Then they report they investigated and found nothing, and in a bit of target fixation, people assume it must have been people in the sub. Understandable, but it's not necessarily the most likely/logical conclusion.
"Lost then imploded" explains both by adding only a small extra assumption so by occam's razor is strictly superior to imploded straightaway as far as I can see.
My money is on simple catastrophic failure of the hull and it not being detected either because the private company is run by jokers who weren't listening for it or because they have been running around like chickens with their heads cut off because the CEO and paying customers just died and they don't want to have to report that to the family, government, media, insurance company, etc... Either explanation is plausible, but I'm slightly more inclined to go with the second simply because they were actively trying to communicate with the sub when it happened and it seems so improbable that they could miss it.