Harvard Team's Big Bang Findings Called into Question

A European study into the origins of the universe is shedding light and raising questions on data first gathered through a Harvard telescope at the South Pole and unveiled this past spring.

At a panel discussion in March, a team of Harvard researchers led by associate professor of Astronomy John M. Kovac shared evidence of “cosmic inflation,” the expansion of the universe after the Big Bang. The data—which was collected over three years and analyzed over four—indicated that a gravitational repulsion caused the universe’s exponential expansion.

But findings from the European Space Agency’s Planck satellite suggest that the data collected by Harvard’s telescope, BICEP2, did not completely account for galactic dust.

“What Planck did was they basically said the level of polarized dust emission in the BICEP2 region was...higher than anybody thought it was beforehand,” said Kirit S. Karkare, an astronomy graduate student who is working on the Harvard research team.

These findings have raised some questions in the scientific community about the previous claims made by the Harvard team, although many of the implications are still undetermined.

“The models of polarized dust in our galaxy are pretty uncertain actually,” Kovac said. “If they’re all underestimates, there is a possibility the entire signal device which we measured with very high precision could be explained by galactic polarized dust.”

The Planck data, which will be published in the journal Astronomy & Astrophysics, delves more deeply into the polarization patterns of the galactic dust.

“The issue is there’s a particular signature in the cosmic background,” said Marc Kamionkowski, a physicist at Johns Hopkins University who was not a member of the Harvard team but participated in the March panel. “There is dust in the galaxy that emits polarized light that may mimic the cosmic signal.”

The BICEP2 and Planck teams have both taken data from the dust distribution, and Kamionkowski said that researchers need to proceed carefully.

“[There is] a lot more in the data that has not been taken advantage of, and we should be waiting for more careful analysis,” Kamionkowski said.

As the project moves forward, the groups plan to collaborate on their mapping technologies. They will study the signals that are detected by both technologies and could be attributed to dust, Kovac said.

“What’s really remarkable is that all of these experiments basically are looking for extremely, extremely faint signals,” Karkare said. These signals exist as photons and can be observed by telescopes like BICEP2 and its predecessors, BICEP1 and Keck Array.

“Seeing the difference between a billion and a billion and one of these photons is fantastically difficult to do,” Karkare said.

Over the next several months, Harvard researchers and collaborators will also be developing a new telescope, BICEP3.

“Knowledge gets refined as we add more and more data,” Kovac said. He explained that while the public sphere may latch onto and generate headlines, the team’s focus is to clarify the uncertainties.

“What we’ve learned this year is that this is nothing if not very exciting science,” Kovac said. “Whatever the level of dust, the experiment was wildly successful in achieving breakthrough sensitivity. It is our goal to take that same approach and to apply it to a wider swath of sky—hopefully the whole sky.”

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