Now we have ten planets (or is it eight?) circling our sun. Is nothing sacred? What about "My very educated mother just served us nine pies?" What other "facts" from my childhood were incorrect. Are we sure we just have one sun in our solar system?
Maybe that's why I like mathematics and theoretical computer science. Eight plus seven will always be fifteen; nondeterministic space will always be closed under complement. We know what we know; we know what we don't know; sometime what we didn't know we now know but nothing we knew later becomes false.