An equation that would summarize all the physical forces in the universe. Why do the stars shine? Why does the galaxy light up? Why do we have energy on the earth? Most of science fiction is in fact well within the laws of physics, but possible within maybe 100 years. And then we have impossibilities that may take 1,000 years or more. That includes time travel, warp drive, higher dimensions, portals through space and time, star gates, worm holes.
We were shrouded with the mysteries of superstition. People believed in all sorts of different kinds of spirits and demons. What made the planets move? Why do things interact with other things? It was a mystery.
