Since the mid-1980s, astronomers and astrophysicists have been accumulating evidence that the expansion of the universe is accelerating (see the article by Saul Perlmutter in Physics Today, Physics Today0031-9228564200353 https://doi.org/10.1063/1.1580050April 2003, page 53). The simplest way to incorporate that acceleration into the description of cosmology, within the framework of general relativity, is to add a cosmological constant (CC) term to the Einstein equations. Before Edwin Hubble discovered the expansion of the universe, Albert Einstein had originally introduced such a term to obtain a static solution of his cosmological equations. After the cosmic expansion was discovered, Einstein considered his introduction of the CC to be the greatest mistake of his career.

Many physicists were reluctant to consider the CC as an explanation for astronomical data, because the value it would need to have is ridiculously small compared to current theoretical expectations—some 10120...

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