Cosmic Dust Adds Uncertainty to Big Bang Ripple DiscoveryMarie French
Astronomers who announced in March that they had detected the first direct evidence of the Big Bang that formed the universe, said that their observations may have been clouded by cosmic dust.
The scientists, who reported the interference yesterday in the journal Physical Review Letters, said it didn’t change initial data released in March on what they attributed to cosmic microwave patterns from the beginning of the universe. Now more data is needed to rule out whether dust truly interfered with their results, said Jamie Bock, an author of the study and professor of physics at the California Institute of Technology.
“It’s an amazing discovery so there’s a very high bar” for the evidence, Matias Zaldarriaga, a theoretical physicist at the Institute for Advanced Study in Princeton, said in a telephone interview. “At the moment the most conservative explanation fits the data. This could just be contamination from cosmic dust.”
Further experiments are under way and observations of cosmic dust levels must be awaited, said Zaldarriaga, who wasn’t involved in the study. “The whole problem is that there’s not enough data.”
Using a radiation-sensitive telescope stationed in the South Pole, a team of astronomers led by Harvard University astrophysicist John M. Kovac spotted cosmic microwave patterns of the impact of a burst of gravitational energy released less than an instant -- a trillionth of a trillionth of a trillionth of a second -- pointing to the birth of the universe 14 billion years ago. The findings, presented as the signature of the Big Bang, were announced at a press conference on March 17.
“Most of the paper remains unchanged, including the actual data points,” Chao-Lin Kuo, a Stanford University assistant professor and an author of the study, said in an e-mail. “We did soften the cosmological interpretation, given new information” about background levels.
Scientists have theorized that background radiation from the rapid expansion of the universe can be observed as cosmic microwaves. Detecting evidence of gravitational waves leftover from that event would provide the strongest evidence yet of how the universe began.
The results amounted to direct evidence for the “inflation” theory of the universe’s origin, said Kovac’s team, which included scientists from Stanford, the Harvard-Smithsonian Center for Astrophysics and the California Institute of Technology. Alan Guth, professor of physics at the Massachusetts Institute of Technology, is the originator of the inflation theory, which holds that the universe underwent a period of rapid acceleration outward at its very beginning.
Interference from the light of cosmic dust could also cause these results, other scientists said, after seeing the initial study. Unpublished results of other research measuring the presence of cosmic dust and models were used to try and rule that out.
Direct measures of cosmic dust reported in May from the European Space Agency’s Planck satellite indicated polarization from cosmic dust may be higher than those models predicted, Bock said. A combination of the results from the Planck analysis and the results from the South Pole observations should give a definite answer, he said.
“I’m afraid people are going to have to be patient,‘‘ Bock said. ‘‘Until we have direct data. the models can only tell you so much.’’