>> completely secret for decades. Virtually no secrets survive that long.
> How do you know that? If a secret did last for decades, you wouldn't know about it.
No, I meant secrets that quickly came out (that weren't secret for long), versus things that were only revealed after a long time. It's a reasonable yardstick for the degree that things can be kept secret "for decades", my claim.
Things that really have remained secret:
* Where Jimmy Hoffa's body is buried.
* What happened to Judge Crater (http://en.wikipedia.org/wiki/Joseph_Force_Crater)
* What women want. Freud famously asked. but no one knows, certainly not women. This may belong in a different category, since it's not clear that anyone knows the secret.
> A US bomber accidentally dropped a hydrogen bomb out of an airplane into the dessert near Albuquerque, New Mexico, triggering a conventional but non-nuclear detonation. This happened in 1957 but was kept secret until 1986
So that's in the never-revealed secrets column? Just checking.
> This secret [Enigma] was revealed in 1974--after 34 years--because of two books by key intelligence figures.
Actually, it was because of the British Official Secrets Act, that required silence on sensitive matters until the government granted permission, and that was obeyed by all concerned. The books were't simply published, after due consideration they were vetted by the authorities in advance of publication. That example belongs in the well-kept secrets act, because everyone involved obeyed the rules until given permission to do otherwise. If it had been a 50 year silence requirement, I suspect that it would still have been obeyed.
But I think you'll agree that rare exceptions don't disprove rules.
> I'm commenting only about the persistent meme that big secrets are quickly exposed: it's not necessarily true.
Not "quickly exposed", that's not a position I took. Thirty or forty years is sufficient validation for my original claim.