Dragon’s Egg Forward, R.
I’ll simply post a couple of quotes about this hard-science SF novel written by a brilliant physicist:
“Forward’s book is a knockout. In science fiction there is only a handful of books that stretch the mind—and this is one of them!”
—ARTHUR C. CLARKE
“Robert L. Forward tells a good story and asks a profound question. If we run into a race of creatures who live a hundred years while we live an hour, what can they say to us or we to them?”
—FREEMAN J. DYSON