About 61 years after he died, Albert Einstein is still right. The legendary theoretical physicist predicted a century ago that a space time continuum would contain gravitational waves.
This past September, a team of more than 1,000 scientists heard a sound from a billion light-years away that was generated by two black holes colliding. The scientists were working at the Laser Interferometer Gravitational-Wave Observatory, known as LIGO. The announcement of the results, made on Feb. 11, was greeted with considerable excitement by physicists, mathematicians and scientists, with one of them saying that astronomers have long had eyes but this breakthrough gives them ears, too.
I asked Marilena LoVerde and Patrick Meade, Stony Brook University assistant professors at the C.N. Yang Institute for Theoretical Physics, for their take on the big announcement.
DD: How does the significance of any potential finding of gravitational waves compare to that for the Higgs boson particle? Some people have suggested that it’s on the scale, if not larger, than the Higgs boson particle.
PM: I would certainly say it’s a very big discovery. However, unlike the Higgs, gravitational waves were on a much stronger footing that they should exist. The Higgs told us something new about how the universe worked, and it didn’t have to be true — there were many other options. However, gravitational waves are exciting because it’s a validation of the theory we already use, general relativity, and it may provide a new way to search for physics we haven’t discovered yet.
ML: This is absolutely on the scale of the Higgs boson. Similar to the Higgs boson, gravitational waves were predicted and expected to exist — and in fact indirectly measured through the spin down of the Hulse-Taylor binary pulsar — but the direct detection of gravitational waves is an absolute triumph of experimental physics and opens an exciting new era of gravitational wave astronomy.
DD: What has the email traffic about this announcement been during the last week? Have you received emails from scientists, colleagues, collaborators and friends who all want to know what this would mean and what you make of it?
ML: Rumors have been going around for months, but the frequency of people emailing/discussing such rumors and adding pieces of evidence suggesting they were true, and the details of the rumors have all increased significantly in the past few weeks.
PM: Since this isn’t directly my field I wasn’t as involved as with some other rumors, but rumors through Twitter, blogs and conversations with colleagues at other places who heard things were all happening over about the last month.
DD: Is there a chance that whatever was detected was an artifact?
ML: The signal looks very compelling. Of course I haven’t had much time to study the details of the statistical methods used to extract the signal and I’m looking forward to doing that.
PM: I’d say it’s extremely unlikely to be an artifact or statistical anomaly, because the same signal was seen in two separate detectors — one in Washington [state] and one in Louisiana.
DD: Will the existence and detection of gravitational waves open up the sky to enable us to “see” much more than we can now in terms of matter and the universe? Will they help us see and understand dark matter and dark energy?
PM: Gravitational waves definitely open up a whole new way to see the universe. However they won’t directly give us any information on dark matter or dark energy in the foreseeable future. To make gravitational waves that are observable with our technology you need very violent gravitational events, like these two black holes merging that LIGO saw. However, by developing new detectors with better sensitivity we may be able to look back and see other violent events in the history of the universe.