The core of science is testing ideas with evidence. Real science does not follow a single fixed list of steps done by one person alone, because it depends on a community. The scientific community checks ideas through publication, peer review and replication.
In peer review, a journal's editors send an article to several other scientists in the same field. Peer-reviewed work meets the standards of science, but it is not automatically correct. Replication means another scientist repeating a study to see whether the same result appears. A result that cannot be replicated suggests the first understanding or method was not good enough. Scientists often share their methods so others can replicate the work and weed out fraud or sloppy work.
Spontaneous generation was the old idea that meat could turn into flies. In 1668 Francesco Redi tested it with jars of meat. In 1747 James Lind, a naval surgeon, compared six treatments for scurvy in a controlled trial.
A horse named Clever Hans fooled many watchers. In 1907 Oscar Pfungst explained why: the horse was reacting to tiny signals from the person asking. His test was simple. Hans could not answer if the person asking did not know the answer, or if a screen kept him from seeing the questioner's face.
Sometimes two things rise and fall together without one causing the other. Ice cream sales and drownings both rise when the weather is hot. The weather is called a confounding variable here: a third thing that causes both.
In 1854 John Snow, a London doctor, suspected the water from the Broad Street pump after a burst of cholera. Snow found little to see in the water, so he held back from a firm conclusion at first. At Vienna's hospital, Semmelweis tested an idea of his own. On 15 May 1847 he ordered everyone to scrub with chlorinated lime between the autopsy room and the delivery room, and the maternal death rate fell from 12% to 1% in two years.
Checking also means asking who gains from a story. In 1835 a New York newspaper printed that an astronomer had seen life on the Moon. It said the story was copied from an Edinburgh paper and then from a science journal, which made it sound real. The 1835 stories sold newspapers, because the paper's sales and subscriptions rose. A newspaper that makes a big claim can have a reason to make it, such as selling more copies. The paper did not issue a full retraction, even many years later.
Piltdown shows a check that came too late. Charles Dawson announced the find on December 18, 1912, to the Geological Society in London. In 1912 there were no good dating methods, so the claim could not be checked in the way we can now. The jawbone had been treated with chemicals to look as old as the skull, and its teeth were ground down. Scientists wanted to find the first human ancestor in England, and that wish may have made them less careful.
In 1949 the Natural History Museum had a scientist who was not part of the discovery test the jaw and skull with fluorine. Fluorine testing compares how much fluorine bones took up from the soil, and bones buried for the same time should match. In 1953 tests showed that the jaw was an ape's. Who made the fake is not known for sure. The hoax slowed the search for human ancestors, because other fossils did not fit it.
Some popular ideas fail a check. You cannot see the Great Wall from space, because the wall is not visible to the naked eye from orbit. At any given moment not all brain regions are firing at once, but over 24 hours most regions are continually active. A check works on any claim, new or old. Ask who says it, and how they know, and look for a second place that says the same.
Words to know
- replication: repeating a test
- retraction: public correction
- variable: changing factor
- fluorine: a chemical element
- confounding: mixing up
