BOB HIRSHON (host):
Why dark matter matters. I’m Bob Hirshon and this is Science Update.
Astronomers have now proved that most of the matter in the universe actually exists. It’s called dark matter because it’s completely invisible. For decades, scientists have assumed it was there, because the gravity acting on galaxies was too strong to come from visible matter alone – unless we just misunderstood gravity. Now University of Arizona astronomers have confirmed its existence by analyzing the path of light passing by two colliding galaxies. Team leader Douglas Clowe:
DOUG CLOWE (University of Arizona, now at Ohio University):
We didn’t really want to try altering the laws of gravity. That’s much more fundamental to do, than to assume that there’s something we haven’t discovered out there. And so now we can actually turn our whole attention to actually trying to figure out what it is.
Clowe says that’s challenging not only because dark matter’s invisible, but also because its density is incredibly low.
I’m Bob Hirshon, for AAAS, the science society.