Cosmologists conjecture that some of the photons came from the regions in which matter was already more densely packed than elsewhere in the early days of the universe. Precisely these agglomerations were the seeds from which galaxies and stars eventually sprouted. "Thus, the earliest structures of the universe are frozen into the microwave background radiation," explains astrophysicist Ensslin, a member of the team evaluating the Planck satellite data.
The team is searching for conspicuous patterns in the temperature distribution, which will provide critical information on the details of how the universe was created -- such as how quickly the universe has expanded since then, how much normal matter it contains, as well as how much invisible dark matter, the composition of which is still somewhat of a mystery. All previous measurements of background radiation, which were admittedly still quite inaccurate, seemed to confirm the standard model of the big bang, or inflation theory. According to that scenario, the universe was literally created out of nothing.
The idea is that all being began in the realm of the microcosm. According to the wondrous laws of quantum physics, even a vacuum isn't entirely empty. Ghostlike particles are constantly forming and then disappearing again. Nuclear physicist Hans Christian von Baeyer used poetic words to describe the dynamic vacuum: "It's like a still lake on a summer's night, a lake whose surface ripples gently while pairs of electrons and positrons everywhere light up like lightning bugs."
But something far more dramatic can take place in the microcosm. It isn't just that particles appear out of nowhere. It's also possible for the vacuum to jump into a higher energy state, just like that. This vacuum energy then acts like anti-gravity, explosively pushing space apart, which is precisely what led to the big bang.
According to inflation theory, within a fraction of a second an area of space smaller than an atom grew to the size of the universe we can comprehend today. At the end of this inflationary expansion phase, the gigantic amount of energy stored in the vacuum transformed itself into radiation and matter. The first stars were born 200 million years later.
Very few cosmologists expect the measurements from the Planck satellite to contradict inflation theory. It would be a huge surprise if they did. But the satellite data could force physicists to come up with more cumbersome equations.
"Of course, a theory can eventually become so complicated," says Ensslin, "that we really don't want to believe in it anymore."
According to the standard model, mysterious particles known as inflatons were responsible for the expansion at the beginning of the universe. They must have left behind a characteristic pattern in background radiation, which would be visible in the Planck satellite measurements. It could also turn out that different types of inflatons had to exist. But it's still completely unclear how several types of these exotic particles could have been created.
Those who are skeptical about the inflation model hope that the Planck data will even furnish clues to a completely different story of the creation of the universe. For them, creation out of nothing seems too much like a mathematical magic trick.