Although Albert Einstein's theories laid the foundation for the creation of the atomic bomb, the only thing he really invented was a refrigerator. Invented in 1926 in conjunction with his former student Leo Szilard, the Einstein refrigerator did not require anything but a heat source for operation — it didn't even need electricity — and he received a patent for it.
Einstein's Theory of Relativity was used in creating the first atomic bomb. Einstein had written a letter to Franklin D. Roosevelt in 1939 concerning the possibility of the atomic bomb's creation and his suspicion that the Germans might be developing such a bomb. Einstein also settled the case for why the sky is blue and won a Nobel Prize in 1921 for his discovery of the law of the photoelectric effect.