Here are some of my favorite sci-fi short stories and novels. Many of these are high up the sci-fi hardness scale, and may be quite demanding on the reader (e.g. require that they pay attention to several pages of infodumps). Several of these were written a fairly long time ago, but they should, for the most part, still stand up to the test of time.
You can read this fantastic short story in just a few minutes, whilst you're on the toilet. If you've never read any sci-fi, and especially if you think sci-fi is just overly masculine starship captains with funny-sounding laser pistols, start with this to get a modernist view on what sci-fi can mean and do as a literary style.
This short story clocks down at a little under 5 thousand words; more than enough for Asimov to crea