  In 1956/1970 Gamow wrote that much later, when he was discussing cosmological
problems with Einstein, he remarked that the introduction of the cosmological
term was the "biggest blunder" he ever made in his life. But the cosmological
constant rears its ugly head again and again and again. Apparently, Einstein
himself has never used the apercu "biggest blunder"; nevertheless a vast
literature grew up around this notion and associated it with Einstein. The
present work is prompted by questions put by Mario Livio in his latest book
"Brilliant Blunders" as to the phrase "biggest blunder": Did Einstein actually
say, "biggest blunder"? I show that in 1947 Einstein wrote Lemaitre that he
found it "very ugly" that the field law of gravitation should be composed of
two logically independent terms. Earlier, in 1922 Einstein wrote Max Born that
he committed "a monumental blunder some time ago". In 1965 Born commented:
"Here Einstein admits that the considerations which led him to the positive-ray
experiments were wrong: 'a monumental [capital] blunder'". It is likely that
when Einstein met Gamow he formulated his views in his native German, and
perhaps he told Gamow that suggesting his cosmological constant was a
"blunder". I suggest that, Einstein perhaps told Gamow that the cosmological
constant was a "capital blunder" or a "monumental blunder", and Gamow could
have embellished Einstein's words to become the famous apercu "biggest
blunder".
