Editor's note: This article originally appeared in the March 1961 issue of Scientific American. In the days when civilized men believed that the world was flat they had no reason to think about gravity. There was up and down
Read More »Editor's note: This article originally appeared in the March 1961 issue of Scientific American. In the days when civilized men believed that the world was flat they had no reason to think about gravity. There was up and down
Read More »