We usually focus on the great theories of science: the elegant ideas that suddenly made sense of the world. But not every idea is a winner, and throughout history plenty of theories have been proposed and have caught on, only to be spectacularly disproved.
Here we celebrate some of the most incorrect yet interesting ideas in science: theories that sought to explain our planet, our minds, and our universe. The scientists behind them may have gotten things very, very wrong, but they came up with some creative suggestions.
Christopher Columbus sailed across the Atlantic using a compass for navigation, but he had no idea how the darn thing worked. Nobody did, back then. Columbus speculated that the pole star itself pulled the compass needle to the north. Later navigators believed that there was an enormous magnetic island at the North Pole that no ship would ever be able to approach, because it would tear out all the ship's metal fittings. The island, called "Rupes Nigra," or Black Rock, appeared on maps in the 16th and 17th centuries.
When 17th century chemists watched a piece of wood burst into flames, they believed they were watching the release of a mysterious substance they called phlogiston. Any material that burned easily in the air was thought to be rich in the colorless, odorless vapor.
The theory explained why a heavy piece of wood was reduced to a light pile of ash: the substance had lost its phlogiston to the air. Chemists also noticed that wood burning in a closed container didn't burn completely, and suggested that the air could only hold so much phlogiston.
Antoine Lavoisier eventually put an end to the phlogiston theory when he recognized and named oxygen, and declared that it was the key component in combustion.
As soon as Europeans charted the shapes of the continents in the New World, they began to wonder if those land masses had once fit together, with South America snuggling up to Africa. But how could they have moved so far apart? At the turn of the 20th century, the Italian geologist Roberto Mantovani published a hypothesis: the planet was expanding.
Once, his theory went, a single land mass covered the entirety of a smaller planet. But then thermal expansion stretched the planet's surface, and volcanoes broke the land into smaller continents. The planet continued to expand in the areas where land had been ripped apart, and oceans filled in the basins, he argued.
Mantovani gave it a good shot, but Alfred Wegener's theory of continental drift soon won out.
Aristotle was the first to suggest the theory of spontaneous generation: that life could arise from "putrefying earth or vegetable matter," or from the "insides of animals." Amazingly, the theory held sway for about 2,000 years. Frogs were thought to spring from rich river mud, mice were believed to arise in moldy grain, and maggots were thought to form naturally in rotting meat.
Francesco Redi disproved spontaneous generation in the 17th century with one of the first controlled scientific experiments. He placed veal chunks in both open and covered, fly-proof flasks, and found that maggots only appeared in the open flasks. Two centuries later, Louis Pasteur proved that spontaneous generation doesn't explain bacterial growth, either.
Determining the nature of light and how it moved was one of the knottier problems of science for millennia. In 1704 Isaac Newton chimed in and declared that it consisted of particles that moved through a medium called luminiferous aether, which pervaded the universe. Other scientists put forward a wave theory of light, but they too believed that light waves traveling from the sun to the Earth must move through some medium: the aether.
Luminiferous aether was accepted as fact until the famous Michelson-Morley experiment, which attempted to detect the "aether wind" created by the flow of aether across the moving Earth. In what's been called the most famous failed experiment ever, their null result suggested that there was something slightly wrong with the theory.
In the 19th century, scientists were competing to explain the marvelous diversity of species on the earth, and not everybody bought into Charles Darwin's ideas about evolution through natural selection. One alternate proposal suggested that a new species came to be when an embryo added a new stage of development--arguing, for example, that primate embryos took an extra step at some point to beget the first humans.
The German scientist Ernst Haeckel was one of the strongest proponents of this so-called recapitulation theory. He held that the developing embryo reprised each stage of evolutionary progress, so that a human embryo started as a single-celled protist, then took the form of a fish, and so on through reptilian and mammalian stages of development.
In Charlotte Bronte's novel Jane Eyre, the protagonist studies her future love interest and finds "a solid enough mass of intellectual organs, but an abrupt deficiency where the suave sign of benevolence should have risen." Bronte, like so many other 19th century intellectuals, was fascinated by phrenology, which explained human personality traits by charting the bumps on the skull.
The German physician Franz Joseph Gall thought up the theory, suggesting that the brain was composed of many modules that had specialized functions--one area was concerned with the appreciation of beauty, for example, while another dealt with acquisitiveness. Areas that were more developed bulged out, and the cranial bone conformed to both bulges and dips, Gall said. Phrenological societies and journals sprang up to explain how to read heads, but by the 20th century the field had been dismissed as pseudoscience.
There was something very comforting about the theory of the steady-state universe. In the 1940s, a handful of cosmologists developed the notion that even though the universe is definitely expanding, its appearance stays the same over time. In other words, it is what it is, and always was and always will be. The theorists suggested that matter is continually being created to keep the density of the universe the same as it expands.
Problems with the theory became apparent in the 1960s, and soon the discovery of the cosmic microwave background radiation killed the steady-state theory. That diffuse radiation is left over from a time when the universe was smaller and hotter, therefore proving the Big Bang theory of the universe's origins.