A Facebook post claims that theoretical physicist Albert Einstein once said, “We all know that light travels faster than sound. That’s why certain people appear bright until you hear them speak.”

Verdict: False

The statement appears nowhere in Einstein’s written works.

Fact Check:

Einstein famously put forward, along with other important contributions to the field of physics, the theory of special relativity, which suggests that objects can approach but not exceed the speed of light. (RELATED: Did Einstein Say That Technology Would Create A ‘Generation Of Idiots’?)

While the theoretical physicist did discuss the speed of light in his writings, there is no evidence that Einstein authored this specific saying. A search of the Einstein Archive Online returned no results. It also doesn’t appear in Alice Calaprice’s “The Ultimate Quotable Einstein,” which contains more than 1,000 verified sayings and quips from Einstein.

The earliest close match to the statement dates back to 1989, where it was published in a Delaware newsletter as part of a list of quips, according to the website Quote Investigator. It’s unclear, however, whether it originated with Robert Orben or Gary Apple, who both served as editor of the newsletter, or another source altogether.

Einstein has been credited with coining the saying since at least 2009, according to Quote Investigator.