Thursday, March 13, 2008

Novos resultados do WMAP

WMAP gives thumbs-up to cosmological model

With the analysis of two further years of WMAP data announced last week, that view of the early universe has just got even more detailed. As well as placing tighter constraints on parameters such as the age and content of the universe, the five-year WMAP data provide new, independent evidence for a cosmic neutrino background. (...)

“The discovery of the neutrino background tells us that our models are pretty much right,” says cosmologist Pedro Ferreira of the University of Oxford. “Stuff from particle physics that you’re not putting in by hand just drops out of them — that’s pretty cool if you ask me.” (...)

Among the tens of other cosmological parameters that have been tightened by the new WMAP results are the age of the universe (13.73 ± 0.12 Gyr) and its content, reinforcing the unsettling fact that 95% of the universe is made of stuff that science cannot explain. According to WMAP, neutrinos made up 10% of the universe at the time of recombination, atoms 12%, dark matter 63%, and photons 15%, while dark energy was negligible. Today, by contrast, 4.6% of the universe is made of atoms, 23% dark matter, 72% dark energy and less than 1% neutrinos.

“The WMAP5 data don’t change anything we thought, they change what we know,” says Hinshaw. “Despite the enigmas of dark matter and dark energy, the more different threads we can weave together [such as determining the number of neutrinos based on different mechanisms that occur at separate cosmic epochs], the more confident we become in the basic picture.”

Post a Comment