Why Don Physicists Like the Idea of a Vacuum Filled with Energy?
The cosmological constant gives researchers headaches. Although quantum theory says empty space should have energy, the relevant equations predict that the energy should be 10120 times more powerful than the tiny value consistent with the rate of acceleration seen today. At the theoretically predicted value, the universe would have flown apart so rapidly that no atoms would ever have formed. No molecules, no galaxies, no Starbucks. So theorists had been in the habit of tweaking their equations to make the vacuum energy zero, which allows them to justify the fact of their own existence. The theories can explain a giant vacuum energy or none at all. But nobody knows of a way to get a tiny cosmological constant like the one suggested by the supernovae data. “A nonzero cosmological constant is ugly beyond all belief,” says Mr. Krauss, “because it’s small. And it’s too hard.” What If Dark Energy Doesn’t Exist? “We might be completely fooled by the data,” says Gia Dvali, a professor of physi
