One of the most common things I read in science reporting is that Einstein once called the “cosmological constant” his greatest blunder but now, even after he himself doubted such a concept, new cosmological evidence and theories have restored the “cosmological constant” proving that Einstein was so brilliant that even when he thought he was wrong, he was really right.
This is a pleasant myth and one that certainly reinforces the archetypal image of Einstein as humanity’s most brilliant man.
And I’m not here to debate or refute that, he was clearly in the top few of anyone’s list of most brilliant humans.
But I am so tired of reading this that I have to say something.
“Dark Energy” is absolutely not Einstein’s “cosmological constant.” Not in any conceptual way, and Einstein was the most conceptual physicist known. So to say that “dark energy” proves that Einstein was right about the “cosmological constant” is something I am certain Einstein himself would snort and say “balderdash.”
Einstein put the cosmological constant into his equations because his theory of universal gravitation had a problem. If true then over time all matter in the universe would have to fall inward, resulting in a final massive crunch when it all was reduced to an infinitesimal point. This bothered Einstein because he personally believed that the universe was infinitely old, he was really a “steady-state” kind of a cosmologist in the early 20th century. So to explain why gravity had not resulted in a cosmic crunch, he inserted a value in his equations to balance out the force of gravity. But it bothered him because it was an arbitrary creation to achieve an end, and there was no theory that supported its existence.
So when Hubble measured the speed of galaxies and determined that they were hurtling away from us at speeds proportional to their distance, Einstein immediatly realized the implications of this and became one of the most influential supporters of the then new “Big Bang” theory that was the logical result of rewinding the universe to its origin.
One of the main reasons, perhaps the main reason Einstein supported the Big Bang so quickly is because he realized that this removed the need for his mathematical “fudge” and he removed it immediately, and that is why he called it his “biggest blunder.”
“Dark Energy” is not some mathematical fudge that has been created to cause equations to match a theorist’s expectations. In fact it is quite the reverse, Dark Energy is proposed because it, or something like it, is necessary to explain the observed increase in the expansion of the universe.
The fact that the two of these are mathematically and dynamically similar is nothing more than a coincidence. It’s about the same thing as using quantum fluctuation (the appearance and disappearance of fundamental particles in “vacuum” space) to “prove” that Fred Hoyle was right about spontaneous creation of matter in space all along. Especially because Hoyle proposed the spontaneous creation of matter to explain his own concept of steady-state cosmology in opposition to Big Bang theory.
Einstein accomplished so much and advanced physics so far that there is no need to continue this polite fiction that he “predicted” dark energy. I wish people would stop. I imagine hearing Einstein groan every time he hears it, wherever he is today.