Even a great mind like Einstein blunders.
In 1916, Einstein revolutionized the world of science, and the world per se, when he published his general theory of relativity. The groundbreaking theory provided scientists with mathematical tools they never had before and which they used to better understand the complexities of the universe.
With such a mathematically perfect theory, errors are obviously out of the equation. But the behavior of the universe, or at least how scientists observed it, was not cooperating; it was refusing to fit into the equation.
The limitations in technology during that period could have been the reason for the presumed inaccuracy of Einstein’s theory. As luck would have it, astronomers were not able to observe the universe behaving the way Einstein’s theory calculated it to behave. More specifically, the general theory of relativity indicated that the universe was restless, that it was either expanding or contracting. Like a lump of raisin-bread dough – the raisins representing the galaxies –, it was either rising or shrinking and the raisins were supposed to be moving away from or closer to each other.
Astronomers looked up but they didn’t observe the universe being restless; it was, for all intents and purposes, at rest. Could Einstein have made a blunder?
As much as he loathed the idea of having to tinker with his perfect equations, Einstein had to consider the possibility of an unidentified force that was working against the force of gravity, exerting a force that pushed outward equal to the force of gravity that pulled inward. An antigravity force that balanced out the gravitational force of the universe, rendering it motionless, was the most plausible explanation.
So the “cosmological constant” – Einstein’s name for the antigravity force – was added to the theory.
Ten years or so later, astronomers had the most powerful telescope ever built to play with and discover more of the mysteries that the universe had to offer. Famed astronomer Edwin Hubble used this telescope, mounted at Mount Wilson Observatory, to gaze farther into the universe than anyone had ever done before.
Hubble looked, measured painfully carefully, and made an incredible discovery. The telescope allowed him to observe other galaxies outside the Milky Way and his measurements told him that they weren’t at rest; they were moving away from each other. The only explanation was, the universe was expanding, and the galaxies were moving with it.
The Big Bang theory was one of the most important products of Hubble’s discovery; the theory states that the universe started as a single and extremely dense mass of matter which exploded, giving birth to the universe as we know it. The theory also says that the universe has been expanding ever since this explosion. Another result of Hubble’s discovery, and which was not any less important, was Einstein’s “vindication.” Hubble’s discovery proved that Einstein’s original general theory of relativity has always been correct. The cosmological constant did not exist. When Einstein met Hubble at Mount Wilson in 1931, he shook his hand and thanked him. Einstein was quoted as saying that the cosmological constant was “the greatest blunder of my life.”
Fast forward to 1998; an astronomer from Lawrence Berkeley National Laboratory and another team from the Australian National University and the Space Telescope Science Institute, independent of each other, embarked on a quest to find out if the universe would expand infinitely at the same rate or if it would slow down and maybe even stop.
They had use of an even more powerful telescope than what Hubble used. They measured the expansion speeds of supernovas, or exploding stars, at different times of the billions of years of cosmic history. Depending on the distance of the supernova from the earth, the light may take millions to billions of years before it can be seen. The two teams of astronomers plotted the different speeds and distances of these exploding stars over the course of cosmic history and used the data to measure the expansion of the universe. What they discovered was that the rate of expansion of the universe was not constant nor was it slowing down; it was speeding up.
There was only one explanation. Einstein was correct when he corrected his original theory. His “greatest blunder,” as he called the mysterious antigravity force or the cosmological constant, was actually one of his greatest contributions to science.
The discovery that the universe’s rate of expansion is accelerating earned the two teams of astronomers this year’s Nobel Prize. Half of the prize went to Saul Perlmutter of Lawrence Berkeley Lab and the other half went to Brian Schmidt of the Australian National University and Adam Riess of the Space Telescope Science Institute.
Current theoretical physicists call this mysterious antigravity force dark energy and they have plenty of ideas as to what exactly the energy is and how it works; however, they are only just that for now, ideas that may just be waiting for technology to catch up so they can be tested and substantiated.