The concept of a cosmological constant—a tendency for empty space-time to either expand or contract—picked up a bad rep in part because Einstein apparently called it his greatest blunder. Einstein’s problem, however, was that he included it in order to create a static Universe. When it became clear that the Universe was expanding, he quickly dropped the term from the equations he used to describe space-time. Over the past decade or so, the cosmological constant has seen a bit of a renaissance, as cosmologists have found that the Universe isn’t just expanding, but that its expansion is accelerating.

We’re still stumped as to what constitutes dark energy or how it produces a repulsive cosmological constant. But we are beginning to figure out just how much of the stuff is out there. A new paper, being released by Science today, provides a new and independent measure of the value of the cosmological constant. And, because it overlaps with those from different sources, it reduces the error on that estimate by 30 percent.

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Gravitational lens makes dark energy less mysterious