A Short History of Nearly Everything: Chapter 3 Summary & Analysis

On clear nights, amateur stargazer Reverend Robert Evans looks at dying stars from his back-porch telescope in Australia as a hobby. What Evans sees, however, is the stars as they were when their light left them, before traveling many light years toward Earth. The North Star we see now is the North Star as it was 680 years ago—it might have died since then, for all we know.

When a massive star dies, it releases a blip of light as bright as 100 billion suns: those blips are what Evans hunts. He’s so good at it that it’s like covering a Walmart parking lot with dining room tables and shaking a pinch of salt on each one. If you added one extra grain to one of those tables, Evans would be able to spot the difference. He doesn’t have any special training, just a good eye and a knack for memorizing star fields.

In 1930, an aggressive fitness buff, bully, and “irritating buffoon” named Fritz Zwicky coins the term “supernova.” He hypothesizes that if a star were to collapse into a dense, concentrated core, atoms would be crushed together and their electrons and protons would create neutrons, leaving enough energy leftover to make a big light explosion that would be visible across the universe. Despite Zwicky’s “revolutionary” ideas, he has no how to prove his hypothesis. Zwicky also predicts that there’s extra mass in the universe that humans can’t see, which we now call “dark matter.” Five years later, Zwicky’s colleague Oppenheimer popularizes the idea of neutron stars “in a landmark paper” but doesn’t cite Zwicky because of Zwicky’s bad attitude.

Supernovae are extremely rare—spotting one is like standing on top of the Empire State Building and spotting someone lighting a 21st birthday cake in the window of a Manhattan building, which makes Evans’s skill even more formidable. His excellent memory of star fields helps, as does his location (the Southern Hemisphere), and his telescope (which he can move around easily, unlike massive professional telescopes). Most nights, however, Evans finds nothing.

Nowadays, it’s easy to automate the process with a digital camera attached to a telescope that scans the sky, but Evans thinks that kills the “romance” of it all.  Bryson wonders what would happen if a nearby star exploded. He asks astronomer John Thorsten, who tells Bryson that if a supernova were to happen near Earth, it would evaporate the magnetosphere (the magnetic zone around Earth that protects humans from harmful radiation) and annihilate us instantly. Luckily, there aren’t any stars large enough to collapse into supernovae close enough to Earth for that to happen.

Supernovae are important because they explain where the energy came from that was needed to transform the universe’s basic gases to elemental matter after the Big Bang. In 1957, scientist Fred Hoyle shows how heavier elements are formed through supernova explosions, though his colleague W. A. Fowler receives a Nobel Prize for the discovery. Hoyle also shows that the energy released from a supernova enables interstellar material called “gaseous clouds” (with all the matter needed for life) to form and cluster. Controversially, Hoyle also believes that pathogens rain down on humans from space and that the Natural History Museum’s fossils are hoaxes, causing national outcry in the United Kingdom. Nonetheless, Hoyle’s research on supernovae helps scientists to piece together an origin story for “how we got here,” which Bryson summarizes next.  

About 4.6 billion years ago, a 15-billion-mile-wide gas cloud gathered where we are in space, and 99.99 percent of it created the sun. Two miniscule dust grains floated close enough to each other to connect via electrostatic forces, marking the conception of Earth. Grains kept colliding until a few clumps were big enough to dominate their orbits, gather more clumps, and form planets. 4.5 billion years ago, a Mars-sized object crashed into Earth, causing some of Earth’s crust to separate and form the Moon. The moon began orbiting Earth, and its gravitational pull stabilized Earth on its axis.

When Earth was about a third of its current size, an atmosphere of gases including carbon dioxide formed. The sun was much younger and dimmer then, but the carbon dioxide in Earth’s atmosphere created a “greenhouse effect” that concentrated the sun’s rays, warming Earth. If it wasn’t for that early greenhouse effect, Earth would have frozen over and life wouldn’t have got going at all. After 500 million years of further collisions from asteroids and passing debris, life somehow got going. Four billion years later, Earth exists as we know it today.