The weightlessness of space was predicted in the late 19th century by Russian mathematician, Konstantin E Tsiolkovsky. Tsiolkovsky accurately predicted and described the effects of weightlessness and envisioned what life in space might be like for objects, humans and other animals. He proposed free fall and suspension in a liquid as conditions that might simulate weightlessness on earth.
Tsiolkovsky was also interested in the effect of artificially increasing weight on living organisms. A centrifuge will increase the weight (force on a body) even though its mass does not change. Tsiolkovsky centrifuged animals including insects and chickens at 5 X the force of gravity, increasing their weight 5-fold. From his experiments, he concluded that centrifugation at 5 X g produced no harmful effects. This information was important to early thought about space travel and ensuring man’s safety during the travel process.