Astrophysics for People in a Hurry

Want to know what we're made of? Again, the cosmic perspective offers a bigger answer than you might expect. The chemical elements of the universe are forged in the fires of high-mass stars that end their lives in titanic explosions, enriching their host galaxies with the chemical arsenal of life as we know it. The result? The four most common, chemically active elements in our universe — hydrogen, oxygen, carbon, and nitrogen — are the four most common elements of life on Earth, with carbon serving as the foundation of biochemistry. We do not simply live in this universe. The universe lives within us.