Albert Einstein’s colossal mistake

Editor’s Note: Dr. Don Lincoln is a senior physicist at Fermilab who does research using the Large Hadron Collider. He has written numerous books and produces a series of science education videos. He is the author of, most recently, “The Large Hadron Collider: The Extraordinary Story of the Higgs Boson and Other Things that Will Blow Your Mind.” Follow him on Facebook. The opinions expressed in this commentary are solely those of the author.

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We celebrate the 100th anniversary of Albert Einstein's theory of general relativity this November

Don Lincoln: Einstein's biggest mistake sheds light on end of the universe as we understand dark energy

CNN  — 

El Malahim. Ragnarok. Armageddon. Those are terms we use to describe the end of the world.

As we celebrate the 100th anniversary of Albert Einstein’s theory of general relativity this November, we can appreciate the fact that this brilliant scientist came up with ideas that have fundamentally changed our understanding of the universe.

General relativity, in short, tells us that gravity is not quite the force Isaac Newton envisioned; gravity is actually the bending of space and time by mass and energy. This discovery led us to the widely accepted theory of Big Bang, which establishes the birth of the universe as 14 billion years ago.

But what about the death of the universe? For that, we need to turn to dark energy, one of the biggest scientific mysteries of our time.

Don Lincoln

For decades, astronomers thought that an expanding universe bound by gravity should grow quickly in the beginning and gradually slow as the stars and galaxies obeyed gravity’s inexorable tug. The only question really was whether gravity was sufficient to eventually stop the expansion of the universe and bring it all back together in a hot “Big Crunch.” This seemed like a very plausible scenario.

But in 1998, to everyone’s surprise, two groups of astronomers announced measurements of distant supernovae that showed while the early universe followed their expectations, about four billion years ago, the expansion of the universe began to speed up.

In complete contradiction to predictions, it seemed that something was overcoming the effects of gravity and pushing everything farther away at an ever increasing rate. These observations have long since been confirmed.

It turned out that Einstein imagined such a phenomenon when he was developing his theory of general relativity. He envisioned a “cosmological constant” that provided a repulsive form of gravity.

Following the best theoretical understanding and experimental evidence of his time, Einstein first added the term to his equations, but then took it out, as it didn’t seem necessary. Einstein regarded the fact that he invented the cosmological constant as a colossal mistake.

With the discovery of the accelerating expansion of the universe, Einstein’s cosmological constant came back into vogue. But it wasn’t the only explanation.