Albert Einstein 's development of the theory of relativity in 1905 led to the understanding that nuclear reactions could create new elements from smaller precursors with the loss of energy. In his treatise Stars and Atoms, Arthur Eddington suggested that pressures and temperatures within stars were great enough for hydrogen nuclei to fuse into helium, a process which could produce the massive amounts of energy required to power the Sun. In 1935, Eddington went further and suggested that other elements might also form within stars. Spectral evidence collected after 1945 showed that the distribution of the commonest chemical elements, such as carbon, hydrogen, oxygen, nitrogen, neon, and iron, was fairly uniform across the galaxy, suggesting that these elements had a common origin. Numerous anomalies in the proportions hinted at an underlying mechanism for creation. For example, lead has a higher atomic weight than gold, but is far more common; besides, hydrogen and helium (elements 1 and 2) are virtually ubiquitous, yet lithium and beryllium (elements 3 and 4) are extremely rare.