The next step was to investigate what the universe looks like.
The shape of the universe, Krauss said, largely depends on how much matter is in it.
“Very simply, we have to just weigh the universe,” he said. Using powerful telescopes and Albert Einstein’s general theory of relativity, scientists can weigh clusters of galaxies, the biggest known objects in the universe.
“We can use it (general relativity) to weigh this cluster because you can ask how much mass must there be in that cluster and where it must be distributed in order to get the image we get,” he said.
But there’s a problem.
“We have many good reasons to understand that there’s too much stuff there to be accounted for by all the protons and neutrons in the universe,” he said.
Scientists, “with their great linguistic perspicacity,” have termed that “dark matter.” All that really means is that no one knows what it is. Not the “slightest idea,” he said, twice for emphasis.
And most of the universe’s energy (called “dark energy) resides in “empty” space, and no one knows why it’s there. The universe we can see, all the stars and the galaxies, is only perhaps 1 percent of the total.
“So much for a universe made for us. We’re a little bit of cosmic pollution in a universe made of dark matter and dark energy. And it’s changed everything,” he said.
Krauss’ fellow scientists at the dais, especially Frank Wilczek, expressed skepticism during the question-and-answer session about some of his far-reaching statements about a universe from nothing.
“Once you start talking about the laws being random or no laws at all, you really start from nothing at all, I think that’s going too far,” Wilczek said. “I think it’s really within a specific framework that you can discuss these things.”
Krauss didn’t budge, at least not much. He admitted he couldn’t explain how the universe came to be but said it was enough to show that it’s possible that a universe can come from nothing.
“The rest is semantics,” he said.