There's an unresolved dispute over the physical nature of space. It occurs because of what Bacon called our "dull and deceptive human senses." On one hand, space appears empty. This led biblical and modern cosmologists to conclude space is an "empty vacuum." But, when astrophysicists from Newton to Einstein studied space, they found it exhibits physical behaviors - i.e. it carries light and heat. This led them to conclude space is an invisible substance called "the ether." The author explores the ether dispute, and the pressing need to resolve it scientifically.