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Gravitational Waves Seen in the Polarization of Light From the Big Bang

1 Jun 2015, 18:33 UTC
Gravitational Waves Seen in the Polarization of Light From the Big Bang
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THE COSMIC MICROWAVE BACKGROUNDThe oldest light we can see in the Universe is called the cosmic microwave background (CMB) and it is the relic light from the Big Bang. While this light is old, it isn't quite as old as our Universe. Before an event called recombination, the Universe was not transparent to light, so the light couldn't propagate very far before being absorbed. Recombination happened about 380,000 years after the Big Bang and the light from this time is what we observe in the CMB.Everywhere we look on the sky, the frequency of this microwave light is very nearly the same. Since heat can be transmitted through radiation (such as microwaves), we can characterize this light to have a temperature of about 3 K (or about 3 oC or 5.4 oF above absolute zero - the coldest anything in the Universe can be). Why this temperature is the same everywhere on the sky doesn't immediately make sense since the heat hasn't had enough time to be transferred across the Universe.The slight variations in the CMB temperature from opposite sides of the sky as measured by 9 years of data from the WMAP mission. The fluctuation in the CMB temperature ...

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