Dark Energy Hits Tenth Birthday, Still a Mystery

So we're just about ten years into the discovery that the universe is probably blowing apart due to a cosmic, anti-gravitational force called dark energy. And how much more do we know about it?

Scientists have made some headway, but there are still some frighteningly large questions to be addressed. They now agree that dark energy makes up 75 percent of the cosmos. Dark matter, another mysterious substance, commands a 21 percent share. And as for the protons and electrons we all know and love? A mere sliver of the total, at a paltry four percent. The latest issue of the journal Physics World features reflections and insights from two of the leading dark energy astrophysicists, Eric Linder and Saul Perlmutter, of the University of California, Berkeley. They say that planned and potential space missions - like the probe pictured here - could make the next decade an exciting one for astrophysics. Who knows, maybe we'll get really lucky and understand the nature of ten or even, dare I say, twelve percent of the universe!—Gregory Mone