Bethe was known for his sense of humor, and with Guido Beck and Wolfgang Riezler [ de ], two other postdoctoral research fellows, created a hoax paper On the Quantum Theory of the Temperature of Absolute Zero where he calculated the fine structure constant from the absolute zero temperature in Celsius units. The paper poked fun at a certain class of papers in theoretical physics of the day, which were purely speculative and based on spurious numerical arguments, such as Arthur Eddington 's attempts to explain the value of the fine structure constant from fundamental quantities in an earlier paper. They were forced to issue an apology.