The Half-life of Facts.

And in answer to the Hitler question, it is conceivable, but currently unlikely, that a future society might evolve where reference to infamous 20th. century characters is discouraged, banned or officially altered as in Orwell's "Ministry of Truth". I take the controversial view that "existence" is always relative, never absolute, and that the "existence of Hitler" is/was a function of those for whom it might matter. On this viewpoint "it"(the nebulous Hitler phenomenon) may cease to "exist" because it will cease to matter.

As Rorty said "truth is like God". You are using the religious language of absolutes. It is an assumption which works for you but has little to do with the etymology of the word "fact", from the Latin (to construct).

I understood the Wikipedia article just fine.

I guess it's a matter of semantic taste, but I can't bring myself to say that facts are facts whether we're aware of them or not.

Facts are, by (my) definition, constructions describing what I am aware of about reality.

The bushman is subject to the same reality as I: we both suffer inflamed teeth because of the same reality*, but long ago you and I would have explained it differently--with different "facts"--and probably a hundred or more years from now (i.e., eventually) someone else will do it differently again.
*His explanatory facts might have to do with socercery or the like.

I have above differentiated between "persistance" and "permanence". The first can be attributed to common physiology and language of our species with its short history of scientific activity. The second has nothing to add to the first other than a mystical component.

In the Middle ages it was a "fact" that there were four colors in a rainbow, and four elements. Today the physicist Brian Cox writes "whatever can happen, does happen at the quantum level".

Facts are statements about our expectancies and our limited ability to control what we call "the world". What we call the world changes as we change. The word "gravity" implies we know how to predict the movement of what we call "bodies" in what we call "a gravitational field". But do we call that parochial knowledge the fact or do we eliminate the term "gravity" entirely and use Einstein's "space tells matter how to move, matter tells space how to curve" as the fact ?

I cannot agree. Evidence from empirical, naturalistic science is very much to the point in a discussion of facticity. Meillassoux's definition of facticity is the ultimate example of question begging, because it assumes as a premise an absence of reason for reality. That is called, in the parlance of inappropriate card players, stacking the deck. Essentially, you have now defaulted to your favorite rhetorical position, which is that if one does not agree with you, it must obviously be because that one is not capable of understanding the subtleties of your religious faith . . . excuse me, your opinion.

A recent book by Samual Arbesman describes the transient nature of what we call "knowledge", such that any statement we call " a fact" today has a finite life expectancy of staying valid in the future. The analogy is of course drawn from the radiactive decay of elements.

Does this put another philosophical nail in the coffin of "absolutism", whether it be couched in religious terms or statements about what we call "reality"?