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Original post by Mika McKinnon on Space

Have physicists finally detected gravitational waves?

The Harvard-Smithsonian Center for Astrophysics has news so big it announced that it would announce something. The press conference will stream live tomorrow at noon, but cosmologists everywhere are gossiping about what that news could be. The leading theory: Scientists have detected gravitational waves, in what would be a landmark discovery for the field of physics.

Gravitational waves are the last chunk of Einstein's General Theory of Relativity that was predicted but not yet observed. If gravitational waves have been observed, it most likely was done by the Background Imaging of Cosmic Extragalactic Polarization (Bicep) telescope at the south pole. It stared at the cosmic microwave background radiation from 2003 to 2008, but it takes a long time to process and analyze the data when looking for a faint signal in a lot of noise.

Have physicists finally detected gravitational waves?

2007 photograph of telescopes at the Dark Center at the Amundsen-Scott South Pole Station. From top to bottom, the partly-buried AST/RO, QUaD, Viper, and finally BICEP and SPT at the bottom. Image credit: Robert Schwarz

The Bicep mission page describes anticipated gravitational waves as faint, polarized, and distorted by gravitational lensing of objects between us and the cosmic microwave background radiation. They released a video of their observations in 2008. The colour scale adjusts throughout the movie to highlight temperature fluctuations of both the cosmic microwave background radiation, and the galactic plane:

Why look at the cosmic microwave background radiation for signs of gravitational waves? Because an infinitesimal moment after the universe started — 10-34 seconds after the big bang — we think it went through an inflationary period. If it did, that inflation could have amplified gravitational waves to such an extent that we can actually detect them. This would not only fill in that last missing chunk of things predicted by General Relativity that we haven't seen yet, but also offer a glimpse into the primeval universe. They won't be insta-proof that inflationary theory is correct, but they would rule out some cyclic theories for the origin of the universe.

Some pre-announcement articles are already mixing up very common gravity waves with gravitational waves. To differentiate, I'll pass things off to an exasperated Dr. Katherine Mack:

Have physicists finally detected gravitational waves?

Gravity waves are common phenomena in both the ocean and the sky, as seen in this MODIS image. Read more about them at the Earth Observatory.

As for the press conference, I'm already bracing for disappointment. "Breaking news! We'll have breaking news for you on Monday!" announcements produce so much hype that the actual discovery probably won't live up to expectations. I'm not the only one feeling that way — the Guardian ran an entire piece interviewing cautiously excited cosmologists warning that the observations would need to be highly robust if they're going to be momentous.

Update: What, you can't wait until Monday to confirm that this is all about gravitational waves before learning about them? Preposterous Universe has a detailed, lovely write-up on the topic with enough math to satisfy even pernickety cosmologists.

Update 2: Alright, I guess that lived up to the hype...

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