Have you ever spent hours looking for something you just know is there, only to be doubted? In 1987, most astronomers thought there was nothing in the outer solar system, …

Extra dimensions of space — the idea that we are immersed in hyperspace — may be key to explaining the fundamental nature of the universe. Relativity introduced time as the fourth dimension, and Einstein’s subsequent work envisioned more dimensions still — but ultimately hit a dead end.

How much brain do you need to be smart? Bees and ants perform marvels as colonies, though each insect has barely any brain. And plants—with no brain at all—exhibit behaviors …