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Physicists report gravity wave signature of the Big Bang

Mar 19 / 14

Scientists have found evidence that instants after the Big Bang, the universe expanded in a staggering burst that created ripples in space-time.

A group of researchers including CIFAR Senior Fellows Barth Netterfield and Mark Halpern co-authored papers released this week from the BICEP2 experiment, a South Pole study of the oldest light in the universe, called the Cosmic Microwave Background (CMB). The experiment appears to have detected gravitational waves which were caused by the universe’s rapid growth a trillionth of a trillionth of a trillionth of a second after it was born, an expansion physicists call inflation.

“What we believe is that during this inflation, all kinds of ripples and wrinkles in the universe became larger and smoother,” Halpern says. “It’s a little bit like you’ve got a wrinkled tarp and you’re stretching it out, and all these wrinkles become smaller and smaller. And then if it ends suddenly, you’re left with some residual wrinkles.”

Halpern, a member of the Cosmology & Gravity program along with Netterfield, built the detector readout system for the BICEP2 radio telescope’s new, ultra-sensitive cameras, which allowed it to detect these residual wrinkles and show that they appear to include gravitational radiation.Halpern says the data need verification, but renew hope for a theory that aligns our understanding of particle physics and cosmology.

“There was a hope that we would understand the particular particle physics that leads to this phase transition,” Halpern says. “That it would all come together in a tidy bundle, that particle physics and cosmology would match and would explain each other.”

However, the particular signature of gravitational radiation is very faint and difficult to detect. Halpern says researchers feared for years they simply wouldn’t be able to see the signal, which would thwart them from completing this harmonious picture of the universe in which the particle interactions and the birth of the Universe fit neatly into the same theories.

But the signal came, and it seems to correspond with existing predictions.

“It gives us this hope again that we’re back in the game,” Halpern says.

If correct, the evidence would also disprove several other theories, charting a new course for the future of cosmological research.


Harvard University, which runs the BICEP2 experiment, announced the new results in a press conference on Monday.

UPDATE June 2, 2014:

Researchers inside and outside of CIFAR are debating the BICEP2 results in light of new evidence suggesting there could have been errors in the methodology. Please see CIFAR News & Ideas for the latest on this story.