In a throwback to another era in cosmic history, astronomers last week discussed the birth of the universe in a 15th-century palace, the Palazzo Costabili in Ferrara, Italy, where the amenities do not include Internet access.
The subject of Planck 2014, as the meeting is called, is a new baby picture — and all of the accompanying vital statistics — of the universe when it was 380,000 years old and space was as hot as the surface of the sun. The portrait taker was the European Space Agency’s Planck satellite, which spent three years surveying a haze of microwave radiation left over from the last moments of the Big Bang with a bevy of sensitive radio receivers.
The data will not be published until December 22 in the journal Astronomy & Astrophysics, and it largely confirms and refines the picture from a temperature map of the microwaves that Planck scientists, a multinational collaboration led by Jan Tauber of the ESA, produced in 2013, showing the faint irregularities from which gargantuan features like galaxies would grow. Its microwave portrait reveals a universe 13.8 billion years old that is precisely mysterious, composed of 4.9 per cent atomic matter, 26.6 per cent mysterious dark matter that is not atomic, and 68.5 per cent of even more mysterious dark energy, the glib name for whatever it is that seems to be blowing the universe apart.
The result is a resounding victory for a sort of standard model of cosmology that has grown up over the last two decades, said Lyman Page, a Princeton astrophysicist. “It’s amazing that just six parameters describe the universe,” he said.
Cosmologists still do not know what dark matter — the material that provides the gravitational scaffolding for galaxies — is, but the Planck results have increased their knowledge of what it is not.
Space experiments like NASA’s Fermi Gamma-ray Space Telescope and Alpha Magnetic Spectrometer have recorded excess cosmic ray emissions that, some say, could be evidence of a certain kind of dark matter particles colliding and annihilating one another.
After Planck, we need another answer for those experiments, the French agency concluded in a statement. Neal Weiner, a particle theorist at New York University, who is not part of Planck, concurred. That model of dark matter, he said, if not completely excluded, now could be severely constrained.
Planck dealt a blow to another possible dark matter candidate, namely a brand of the ghostly particles known as neutrinos. Physicists have known of three types of neutrinos for some time and have wondered if there were any more, whose accumulated mass would affect the evolution of the universe. Planck’s results leave little room for a fourth kind, so-called sterile neutrinos.
Compounding the frustration of cosmologists in the room in Ferrara and at large was an issue that has galvanised them for the better part of a year: whether astronomers had detected the very beginnings of the Big Bang in the form of space-time ripples known as gravitational waves.
The added value of the data is a map showing how the microwaves are polarised, information that could shed light on what was going on when the universe was a trillionth of a trillionth of a trillionth of a second old, and in the grip of forces about which physicists can only speculate.