Friday, March 21, 2014

Microwave telescope down at the South Pole finds gravitational waves from the Big Bang

On Monday March 17th something spectacular in science was announced. A readable description appears in a New York Times article titled Space Ripples Reveal Big Bang’s Smoking Gun. A web page on the Nature magazine web site said that Telescope Captures View of Gravitational Waves.

A large team led by John M. Kovacs announced that their little BICEP2 microwave telescope at the South Pole had found a signal consistent with inflationary gravitational waves. (BICEP is an acronym for Background Imaging of Cosmic Extragalactic Polarization). You can read the draft of their magazine article here. They concluded:

 “....The power spectrum results are perfectly consistent with lensed-ΛCDM with one striking exception: the detection of a large excess in the BB spectrum in exactly the l range where an inflationary gravitational wave signal is expected to peak. This excess represents a 5.2σ excursion from the base lensed- ΛCDM model.

....The long search for tensor B-modes is apparently over, and a new era of B-mode cosmology has begun.”

This is a cool experiment, both figuratively and literally. National Geographic has a web page about why The South Pole is a Great Place to View Space. The air temperature at the pole averages -72 degrees Fahrenheit, or 215 Kelvin (where zero Kelvin is absolute zero, as cold as you can get). The telescope is cooled by liquid helium down to 4 Kelvin, but at the focal plane the detector is refrigerated even further to only 0.27 Kelvin.

There are lots of people and stories behind this discovery. (The magazine article lists 47 authors). One Caltech web page is titled Building BICEP2: A Conversation with Jamie Bock. He mentions the late Andrew E. Lange. The last sentence in the magazine article draft is:

“We dedicate this paper to the memory of Andrew Lange, whom we sorely miss.”  

The image of ripples is from Roger McLassus at Wikimedia Commons.

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