It’s official: data from the Planck satellite has revealed no signs of gravitational waves embedded in the cosmic microwave background, the primordial ‘echo’ of the Big Bang that occurred nearly 14 billion years ago.
This landmark result contradicts the now-infamous BICEP2 announcement of the discovery of gravitational waves last March — but this is not the end of gravitational waves, nor the theories behind inflation. In fact, according to cosmologists, we can expect the search to intensify over the coming months and years.
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After the details behind the Planck observations were revealed this week, Discovery News was able to speak with cosmologist Kendrick Smith, of the Perimeter Institute for Theoretical Physics in Ontario, Canada, to find out what impact these Planck data will have on our quest to understand what happened when the universe was born.
To recap, in March 2014, researchers of the BICEP2 telescope made a very public announcement that they had discovered the fingerprint of gravitational waves in the most ancient radiation observed in the distant universe — the cosmic microwave background, or simply, the CMB. This radiation is the remnants of the Big Bang and therefore originates from the genesis of our universe.
By studying the CMB, cosmologists are looking into a cosmic time capsule of sorts — the features etched into this radiation were created moments after the Big Bang, so their structure can reveal the conditions (and therefore the physics) of our universe back in the beginning of time.
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How the universe began is “one of the biggest open questions cosmologists are trying to answer,” said Smith. “There are several different theories on what happened shortly after the Big Bang … the problem isn’t that we don’t have a successful theory, it’s that we have too many successful theories! We’re trying to narrow down the possibilities.” Although Smith isn’t directly involved in this week’s joint BICEP2/Planck publication, he is a member of the international Planck Collaboration.
One theory is that the universe underwent a rapid expansion immediately after the Big Bang and one possible way to detect whether that inflationary period occurred is to look for gravitational waves etched into the CMB.
The BICEP2 telescope, based near the South Pole, is designed to specifically seek out a type of polarization in the ancient CMB radiation called “B-mode polarization.” Should B-modes be detected, it’s a sign that gravitational waves are present, proving certain inflationary universe theories.
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