Feb 07, 2026
To:Alexander Vdolainen
Three decades ago, I was a pro-nuclear activist. My like-minded friends and I wrote opinion pieces promoting nuclear power in a Sweden that was decidedly anti-nuclear at that time. Fast forward 30 years, and I'm happy to say political opinion here is finally beginning to catch up with the technical reality we posited back then.
I'm something of a MOND guy myself. Or perhaps more accurately, I'm concerned that decades of search for working dark matter and dark energy theories have come up with nothing provable, and the remaining hypotheses are increasingly becoming more and more... odd. And to me, that makes MOND win by default at the moment as the best non-dark matter theory around, though I don't rule out that the lack of evidence for MOND will one day make me lose faith in that as well.
Anyway, in terms of my sci-fi classification, using MOND would make a story hard sci-fi, but not pure hard sci-fi. Again, this is just my personal definition and I fully respect that yours differs from mine. But I often bring up Clarke's Rendezvous with Rama as an example here. The book depends heavily on known, proven, existing physics - except for the last chapter where Rama turns on its non-Newtonian space drive. But to me, that single chapter is not enough to disqualify the entire Rendezvous from being hard sci-fi, because the space drive only adds on top of established physics. It doesn't say Newton or Einstein are wrong. It just adds extrapolated physics on top of that.
In the context of FTL, that means any story where you literally go faster than light, to me, is soft sci-fi, because doing that explicitly goes against relativity. Bypassing the light speed limit while still retaining Einstein, on the other hand, I have no problem with, as long as it's not done with just handwaving. To me, that's still hard sci-fi, if it's done properly. But it's not *pure* hard sci-fi.
But I think the main takeaway is that there are no official definitions of these sub-genres, and that even personal definitions can get blurry at times. The important thing is to be honest and to write stories we would enjoy reading ourselves.
