The phrase "knowledge explosion" usually refers to "what is known" in some abstract sense, as if there was an official (World) Storehouse of Knowledge (WSoK). A common way to quantify it, so as to draw exponentially rising graphs, is to count academic journal pages, or maybe not all, but certainly scientific journal pages.
Yesterday I asked myself: "If one person in some discipline has arrived at some correct conclusions, such that a decade from now everybody will know he was right, while the other hundred people in their discipline think the opposite and even supposing his argument or demonstration would pass muster with the toughest epistemologists* can we say 'it is known', or it belongs in the WSoK?"
Certainly not I think. We might try to get around this quandary by saying the fact has entered the WSoK or simply "it is now known" when some critical mass of "the" pertinent discipline has been persuaded. But is "the" pertinent discipline a valid concept? Consider the history of plate tectonics becoming "accepted science", as described in last section of "Science in a nutshell".
A really large fact, such as the movement and rearrangement of continents over time, may have implications for several different disciplines. It may be accepted and well demonstrated in one discipline, while in another, current theory contradicts it, then we must accept people in that discipline saying we don't agree or at least this is not been demonstrated to our satisfaction there seems to be a contradiction when we look at the facts of our domain. Then again, some may disregard it if the dissenting discipline is much less of a "hard science" than the one in which "it is known".
We might tend to call continental drift, or plate tectonics, "settled science" when the last of the disciplines with a stake in it was able to say we "we find strong evidence for this within OUR discipline."
Here is an "important, if true" observation. Within the hardest and least ambiguous scientific disciplines, facts have a sort of a global self-propelling quality, such that their becoming part of the WSoG is a self-organizing (social) process; they are like a kind of life form; "memes", but in the most positive sense. I'm talking about non-local facts about SPECIFIED arrangements of matter, OR facts about one particular object (such as the planet Jupiter) observable by anyone (not, e.g., "my soul" or my feelings about X, or a spirit that only comes when asked in the "right way". Hence we
Human events, and facts about societies may be just as real, but certainly lack a global self-propelling quality. They have an unfortunate tendency to be propagated by those whose purposes they serve, and denied by those whom they don't serve.
I assert (though I doubt I'll get universal agreement) that history has one thing in common with hard sciences. A sufficiently literal/objective claim about an event either is or isn't true (unlike in the case of political principles). It's philosophically conceivable that we really live in some kind of dream logic or Hollywood script logic in which something that happened can unhappen but according to my axiom, and this is a sort of faith, we DON'T live in that sort of universe, but in a universe where a sufficiently literal occurrence either happened or it didn't, and nothing can change that fact. BUT here's the rub. We believe this despite the fact the vast majority of "things that happened" appear to be unknowable, because nobody observed them, or maybe one or more person did, but their witness can be doubted.
Actually, we have to admit this is even false at the level of quantum mechanics but for all practical purposes, true at a macro-level. Maybe someday, some amazing use of quantum mechanics will produce a TRUE ambiguous fact at the macro level; a real life Schroedinger's cat, but that does not seem worth dwelling on for now, and we are stuck with, say, the person who either was or wasn't taken up by extraterrestrials on a certain date, and examined and then returned to Earth. I, at least, claim that we have to say this either happened or it didn't.
Returning from history and the world of transient happenings, a really USEFUL hard, non-local physical fact, can not only stand on its own, seemingly causing "knowers" to accumulate just by virtue of being true, written down in the right sort of place, and useful. Such a fact ATTRACTS knowers; i.e. it can "go viral", and its truth, importance and usefulness, in the right sort of society, will tend to generate widespread agreement via a self-organizing process.
Now, transient "facts" are about as unlike this as they could possibly be. They will not go viral on their own, or if they do, there is likely to be something dishonest about the process; such viral "facts" are often not facts, but disinformation.
Even if true, and of vital importance, such facts really need a lot of help to actually be known to any useful extent. They need reporters at the very least; actually, they need advocates; some structure of people committed (if only for the money) to making some things known, which means that someone (or more than one) must judge them IMPORTANT. Can we distinguish honestly modivated reporter/advocates from propagandists? For this we need honest brokers. In fact, we need a very powerful structure of brokers and an inquiry into what would make such brokers, and/or some process of capturing and recording events that really happened.
Humanity is moving along on a path whose endpoint seems to be indistinguishability of real and fake news. To prevent this, I suggest we will need institution(s) into which we pour a huge amount of energy, making them work, and ensuring that we can trust them.
To that end, we need to understand the process by which one or more people's observation is reliably turned into knowledge. We need this more urgently than we need a more perfect definition of what exactly is knowledge, and what isn't quite knowledge, an inquiry that shows little signs of progress IMO.
* Philosophers of Knowledge, whose main concern has been to define knowledge, or ask how do we know what we know.