Imaginary Science?

Reading Poul Anderson's articles on "imaginary science" and on hard sf, I realize that I have been making a more simplistic distinction between hard sf, epitomized by, e.g., Blish, Anderson and Niven, and another, unnamed, kind of sf, epitomized by Bradbury and Lewis - although I can only think of those two authors to go into that second category. (Addendum, 29 October, 2017: Also, Clifford Simak.)

Thus, I have been classifying faster than light travel, time travel and parallel universes as hard sf although they are consequences of imaginary science, not of known science. However, I cannot feel this as a real distinction. I think that Anderson wrote "hard," scientifically and technologically based, sf just as much when he explained that hyperspace was a series of quantum jumps as when he delineated the environment of the planet Starkad.

The real distinction is between authors who know and care about science and those who do not. In one story, Bradbury accounted for the faster than light velocity of a group of interstellar explorers merely by stating that their speed was the speed of a god, thus evoking not quantum mechanics but a fantasy concept.

Lewis grudgingly acknowledged that the sciences were good in themselves - damning with faint praise - but concentrated his fire on their capacity to be perverted for diabolical ends without displaying any knowledge of scientific principles. To Lewis' character, Ransom, scientific knowledge of the universe is:

"'...the enemy's talk which thrusts my world and my race into a remote corner and gives me a universe with no centre at all, but millions of worlds that lead nowhere or (what is worse) to more and more worlds for ever, and comes over me with numbers and empty spaces and repetitions and asks me to bow down before bigness."
-CS Lewis, Voyage To Venus (London, 1978), pp. 197-198.

Not bow down! But bigness can at least be acknowledged. Why are infinite worlds worse? The enemy referred to is literally the Devil. It is Lewis' anti-science that contrasts so sharply with the pro-science fiction of the hard sf writers.