> Also, we've realized the scientific reality that traveling faster than light is likely impossible
I'm confused at what speculative fiction exists from before the 1910s (or thereabouts) which involves FTL? I've no doubt there's a handful of works but this is hardly a plausible explanation for a _recent_ decline in these topics.
> I'm confused at what speculative fiction exists from before the 1910s (or thereabouts) which involves FTL?
I bet very little. We didn’t really know how enormous the universe is (https://en.wikipedia.org/wiki/Stellar_parallax: “Being very difficult to measure, only about 60 stellar parallaxes had been obtained by the end of the 19th century”), and we hadn’t known for long that the speed of light is an absolute speed limit.
I'm confused at what speculative fiction exists from before the 1910s (or thereabouts) which involves FTL? I've no doubt there's a handful of works but this is hardly a plausible explanation for a _recent_ decline in these topics.