Einstein almost tagged dark energy in the early 1920s Letter to
Schrödinger was oh-so-close It’s of historical interest only, at
this point, but an analysis of an exchange between Albert
Einstein and Erwin Schrödinger seems to show how close Einstein
came to predicting the dark energy problem. In this paper,
submitted to Arxiv and described at the Arxiv Blog here, Alex
Harvey of City University, New York, examines a brief letter-
swap between the two – much of it in the layman-impenetrable
maths of relativity. It began with Schrödinger, who in 1918
responded to Einstein’s theory – which included a cosmological
constant that piqued Schrödinger’s interest. Einstein had
created the cosmological constant to account for the state of
the universe as he knew it – fixed and unchangeable. Without it,
gravity would either cause contraction (if it were too strong)
or expansion (if it were too weak) – so Einstein added a term to
maintain the state of the universe (and as we know, when Hubble
demonstrated the expansion of