We all know that light travels faster than sound. That's why certain people appear bright until you hear them speak.

We searched Einstein's published works, collected papers, letters, speeches, and interviews and found no primary source containing this line, and nothing in the Albert Einstein Archives matches its wording. The style is that of a modern comedic one-liner, trading on the double meaning of "bright" — a punchline register that does not resemble Einstein's documented prose, though tone alone would not settle the matter. What tips the balance is positive evidence of a different origin: the joke is documented circulating decades after Einstein's 1955 death, and an early located instance from 1989 credits it to comedian Steven Wright ("Light travels faster than sound. Isn't that why some people appear bright until you hear them speak?"). The book-database appearances that name Einstein are all recent — a 2015 novel, a 2016 novel, a 2019 quote notebook, a 2020 anthology, and a 2024 title — none predating the 1989 comedic attribution, and all are secondary echoes rather than any record of Einstein authoring the words. Taken together, these point to a modern joke tradition with a named competing attribution rather than to Einstein. On the evidence available, we consider this quotation misattributed.