> Can our sci-fi writers come up with something equivalent that is as dizzyingly far from what we know now, as now is from what Aristocreon knew?

Sure they can, but as one of them once opined: any sufficiently advanced technology is indistinguishable from magic.

What we cannot do, is guess which things so different from our world are, and are not, magic. Are the probabilities in quantum mechanics themselves quantised?

Is there an island of stability for fundamental particles, as distantly related to the gap between the electron and tau as silicon wafers are to the gap between titanium dioxide sand and silicon dioxide sand, such that we could use them to create conducting plates fine enough, that they could be placed close enough together, that by the Casimir effect we could construct a macroscopic object with overall negative mass?

Will we ever have a engineering-quality definition of consciousness, or be limited to the kind of pre-paradigmatic thinking that had Diogenes presenting a plucked chicken in response to Plato defining man as a "featherless biped"?

Will we destroy the earth in a way that preserves all the information, and find our minds resurrected a million years hence by strange alien beings?