Over the last fifteen years or so, I have investigated dozens of claims that the Gemara knew something that modern science only discovered centuries later. Initially I was very excited about such possibilities, but as I researched them, disappointment set in. In every case, I found that it was either (a) something that non-Jews in antiquity also knew, (b) something ambiguous that could be interpreted in all kinds of ways, or (c) something that is not actually true.