When Science Got it Wrong: Inside the N-Ray Phenomenon

In early 1903, just eight years after Wilhelm Röntgen discovered X-rays, French scientists believed they had identified an entirely new form of radiation. They called it N-rays, named after the city of Nancy, where the discovery was announced by physicist René Blondlot, one of the most respected scientists of his time.

Blondlot claimed that these rays made electric sparks appear brighter. He reported that he could separate N-rays into different frequencies using a prism coated with aluminum and conducted numerous experiments to understand their properties.

The scientific world, especially in France, quickly embraced the discovery.

Researchers identified supposed sources of N-rays, developed detectors to measure them, and cataloged materials that were said to block or transmit the radiation. One biophysics professor, Augustin Charpentier, even reported that living creatures emitted N-rays. Rabbits and frogs produced them. Muscles emitted them, tendons did not. Exposure to N-rays allegedly enhanced sight, smell, and hearing. Rays from living beings were classified separately as “physiological rays.”

By the height of the phenomenon, more than 120 scientists had published nearly 300 papers on N-rays.

This all looked like science progressing exactly as it should.

Or did it?

Seeing What We Expect to See

Science is supposed to advance through observation, verification, and replication. A discovery is tested, reported, and independently confirmed. But what happens when observation itself is quietly distorted?

Imagine being shown four red candies and asked which two are closest in color. You confidently point to the most similar pair, only to be told you are wrong. It feels absurd. Surely no one can be tricked into misjudging something so obvious.

And yet, people often see exactly what they expect to see.

In 1960, English psychologist Peter Wason demonstrated this tendency in a now-classic experiment. Participants were given simple logical tasks and received feedback that was deliberately false. Even when their own reasoning was correct, many trusted the feedback instead. Wason coined the term confirmation bias to describe this behavior.

We notice countless details every day, but our minds quietly filter them. We remember what fits our expectations and overlook what does not.

In a later experiment, people watched a video set in a shopping-mall scene. When asked what they saw, viewers reported ordinary figures such as a mother with a stroller or a man trying on a suit. Almost none noticed a person in a full chimpanzee costume walking straight through the scene.

Bias in the Laboratory

Physicist David Goodstein, in his book On Fact and Fraud, explains that a surprising amount of scientific research is shaped by biased data collection. Researchers are often unaware that they are interpreting results through the lens of what they already believe.

This is exactly what happened with N-rays.

The illusion might have persisted much longer if not for American physicist Robert Wood, who decided to investigate the phenomenon firsthand. Wood was an expert in ultraviolet radiation and arrived in France skeptical, but open to being convinced.

In 1904, he published a letter in Nature describing his observations.

Wood reported watching an experiment in which N-rays were said to increase the brightness of an electric spark. He saw no difference. The researchers suggested his eyes were not sensitive enough. Wood then proposed a simple test. Without telling them when he did so, he blocked the supposed rays with his hand and asked them to identify when the brightness changed.

They failed every time.

At one point, Wood secretly removed the prism that was supposedly projecting the N-rays. The French scientists continued to observe, measure, and describe the radiation exactly as before.

At that moment, the case was closed. N-rays did not exist.

The Lesson Beneath the Error

Looking back, it is easy to dismiss the episode as a scientific embarrassment. But the deeper lesson is more unsettling.

If Wood had believed in N-rays, he might have seen them too. More than a hundred intelligent, careful scientists did. They were not dishonest. They were human.

This is the power of confirmation bias.

It does not announce itself. It does not feel like error. It feels like certainty.

And that is why the N-ray episode remains one of the most important cautionary tales in the history of science.