Summary

Gravity is “simultaneously the best and the least understood phenomenon in nature” (75); the scientific community understands the origin of gravity as “a warp in the fabric of space and time, produced by any combination of matter and energy,” yet remains “essentially clueless” as to the origin of eighty-five percent of the universe’s gravitational pull (76). Scientists have reached the delicate conclusion that this gravity stems from dark matter. The term dark matter is used to identify not merely invisible matter, but rather, a type of matter or force yet to be discovered. Undetectable by modern technology, the existence of dark matter can only be inferred by its effects on detectable matter like planets, stars, gas clouds, and light.

Tyson credits astrophysicists Fritz Zwicky and Vera Rubin with the observations that proved the existence of an inexplicable yet massive gravitational force operating outside of...