What is the cosmological constant?
By Adam Mann - Live Science Contributor 5 days ago
Not a blunder anymore
Artist depiction of a supernova explosion in space. In the 1990s, researchers used supernovae to identify dark energy's existence, bringing science back to Einstein's once-discarded cosmological constant. (Image credit: Shutterstock)
The cosmological constant is presumably an enigmatic form of matter or energy that acts in opposition to gravity and is considered by many physicists to be equivalent to dark energy. Nobody really knows what the cosmological constant is exactly, but it is required in cosmological equations in order to reconcile theory with our observations of the universe.
Who came up with the cosmological constant?
Albert Einstein, the famous German-American physicist, came up with the cosmological constant, which he called the "universal constant," in 1915 as a means to balance certain calculations in his theory of general relativity. At the time, physicists believed the universe was static — neither expanding nor contracting — but Einstein's work suggested that gravity would cause it to do one or the other. So, to mesh with the scientific consensus, Einstein inserted a fudge factor, denoted by the Greek letter lambda, into his results, which kept the cosmos still.
Yet a little over a decade later, the American astronomer Edwin Hubble noticed that galaxies were actually moving away from us, indicating the universe was expanding. Einstein called lambda his "greatest mistake."
Hubble's observations negated the need for a cosmological constant for decades, but that changed when astronomers examining distant supernovas in the late 1990s discovered that the cosmos was not only expanding, but accelerating in its expansion. They named the mysterious anti-gravity force required to account for this phenomena "dark energy."
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Nobody really knows what the cosmological constant is exactly, but it is required in cosmological equations in order to reconcile theory with our observations of the universe.
