How space is defined relies as much on long-standing cultural misperceptions and conventions as any scientific reality. For example, the tendency to compare space to the ocean often dominates the cultural discourse about it. In addition, the idea that space encompasses a vast area of nothingness is mistaken: Space is full of matter, some of it not yet understood. The authors argue that to discover a pocket of actual nothingness within the universe would truly be remarkable. Still, the farther one travels out into the reaches of space, the fewer particles one finds. However, this does not account for the quantum realm, where matter pops into and out of existence, following none of the rules of classical physics—even if invisible to current technology.

In the early days of the scientific revolution, astronomers sought to explain what existed between celestial bodies by identifying a “heavenly aether.” This allowed them to rationalize the fact that light traveled through space and toward the Earth; after all, it must travel through something rather than nothing. Thus, the movement and makeup of light became of great interest to physicists. Some argued that light functioned as a wave, while others argued that light functioned as a particle.