Did you know that 1965 physics laureate Richard Feynman was an enthusiastic correspondent? One of the most beautiful letters he wrote was to his first love and late wife Arline Greenbaum. The letter was written on this day 80 years ago. Greenbaum was Feynman's high school sweetheart who sadly passed away at the age of 25 from lymphatic tuberculosis. Feynman wrote her a love letter around two years after her death. A segment of the letter read: “When you were sick you worried because you could not give me something that you wanted to and thought I needed. You needn’t have worried. Just as I told you then there was no real need because I loved you in so many ways so much. And now it is clearly even more true — you can give me nothing now yet I love you so that you stand in my way of loving anyone else — but I want you to stand there. You, dead, are so much better than anyone else alive. I know you will assure me that I am foolish and that you want me to have full happiness and don't want to be in my way. I'll bet that you are surprised that I don't even have a girlfriend (except you, sweetheart) after two years. But you can't help it darling, nor can I—I don't understand it, for I have met many girls and very nice ones and I don't want to remain alone—but in two or three meetings they all seem ashes. You only are left to me. You are real. My darling wife, I do adore you. I love my wife. My wife is dead. Rich P.S. Please excuse my not mailing this—but I don't know your new address." This love letter is featured in Feynman's book of letters, 'Perfectly Reasonable Deviations from the Beaten Track', where more of his correspondence can be read. Photo from the Nobel Foundation archive.