It’s like the gatecrasher who won’t leave the party. The cosmological constant, the simplest explanation of why the expansion of the universe is accelerating, just won’t go away, much as astronomers would like to see the back of it.
The cosmological constant originated as a “fudge factor” that Einstein added to general relativity to square its predictions with a universe that he thought was static. He later disowned it, when it was realised that the universe is expanding, but with the discovery in the late 1990s that this expansion is accelerating, the cosmological constant came back into favour.
In essence,…
