Elephants are pregnant for up to two years. Females of some fish species starve for weeks while holding dozens of eggs and hatchlings inside their mouths. And pregnant humans commonly endure months of ...

Exactly 200 years ago, a French engineer introduced an idea that would quantify the universe’s inexorable slide into decay. But entropy, as it’s currently understood, is less a fact about the world ...

Quantum calculations amount to sophisticated estimates. But in 1931, Hans Bethe intuited precisely how a chain of particles would behave — an insight that had far-reaching consequences. By 1928, ...