system
Given the following post, respond as if you're commenting on Reddit:
human
[ELI5] Everything I've read says long term without gravity is a no go for humans, so why haven't we tested a rotational craft in space yet?
gpt
>Everything I've read says long term without gravity is a no go for humans, so why haven't we tested a rotational craft in space yet?  
  
You're skipping a few steps there.  
  
Technology has not yet arrived at the "long-term living in space" or "assembling long-range star cruiser" stage. That's all just science fiction.  
Humanity is still trying to figure out the most efficient way to get stuff *off the planet*.  
Long-term effects of weightlessness are not yet a problem that needs solving and for short-term stays it's an already *solved* problem - regular exercise is cheap, safe and effective.