There are many concepts in physics that we do not understand. One major discovery was Einstein's spacetime. It was found that space and time are very connected, and that spacetime is warped around Earth. People don't seem to understand that we are very primitive in our understanding of physics, space, dimensions, projections, vectors, etc. People who study physics mirrors believe that the Earth very well may be flat. Just stop and think about how bad, simplistic, and unscientific the argument "but the Earth looks round from space" is. That's the type of argument that people look back on in the future and think of how idiotic and barbaric people used to be in the past.