Although Albert Einstein was mostly known for his immense genius, even he was a person with qualities and flaws like any other human being, and like any human he made mistakes. The biggest scientific mistake of the great physicist, which he also admitted, may not be a mistake that we can think of today. Einstein’s biggest mistake, in his own words, was wanting the universe to stay still.
Although he was wrong about this, his worldview pushed him to correct his equations. Still, this correction has appeared again to help humanity understand the cosmos. In 1915, Einstein went beyond the confines of the special theory of relativity and published his general theory of relativity.
It has become an all-encompassing theory of gravity, and it explains not only our universe, but universes very different from our own. But there was something wrong with his definition of gravity for our universe, at least in his view. At the time, Einstein and most scientists believed that the universe was static: It had always been so and had never changed on a grand scale. The Milky Way existed as it always did, and nothing would change that.
But when you put the numbers together to make our little galaxy immortal, a strange result emerges. Everything ends at the same point, turns into a black hole, which is something from equations but unobserved. The Milky Way isn’t collapsing, so to resolve the philosophical conflict, Einstein added an extra parameter to the equation: the cosmological constant.
What is the cosmological constant?
This cosmological constant had no observational justification other than the fact that not everything degenerates into a singularity. But it’s not unheard of in physics to suggest that something exists before observing it.
So when you’re making up a physical parameter that depends on something that might not exist, the best thing to do may be to be open to suggestions and corrections. However, Einstein became quite touchy when he was challenged about it. Scientists who were always wrongly criticised, and often belittled, showed that both Einstein’s own theory and his observations began to contradict this idea. Within two decades, the consensus was overwhelmingly against him, so he decided to abandon the cosmological constant, calling it his “biggest mistake.”
However, the story does not end there and there is a final surprise. In 1998, astronomers discovered that the expansion of the universe is accelerating. The mysterious invisible impulse was called dark energy. And since the story got here, you can guess the current best way to describe it in the general equation of relativity: A cosmological constant! Although this new cosmological constant is not the same as Einstein’s constant, the fact that it is still a constant does not change.
Maybe dark energy can change the situation and the equations in the future, but Einstein’s biggest mistake really embodies the idea that mistakes are a door to discovery.
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