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Cosmology
The next batch of Planck data was released yesterday (very early in the morning here in New Zealand), and this time the big news is that Planck has accurately measured how long it took for the first stars to light up after the Big Bang. The headline story is that the dark ages – the time before stars – lasted roughly 550 million years, 100 million years longer than Planck's previous estimate. (This is a long time, but a fraction of the 13.8 billion years since the Big Bang itself.)
When the news started to unravel, it struck me that the cosmology community was in the same position as someone waking up in an unfamiliar Las Vegas hotel room with a throbbing headache, hazy memories of the night before, and a fresh tattoo reading "r=0.2".
Unfortunately, once the initial excitement died away, a number of voices asked whether BICEP2's signal had a more humble origin -- dust in our own galaxy. Dust can mimic a gravitational wave signal if it interacts with the galaxy's magnetic field. From a cosmic perspective, anything inside our galaxy is a "foreground" – dirt on the window through which we peer at the microwave background, the fossil light from the big bang coming to us from the furthest reaches of space.
When the news of the BICEP2 result broke, the mood was euphoric. There was open speculation about Nobel Prizes, a certain video went viral and cosmologists spoke of a radical transformation in our understanding of the early universe. And all of this may still come to pass. But the wave of doubt blowing through the cosmological community in the last week is growing into a consensus that the BICEP2 team has overstated the case for a discovery.
It's possible that the cosmology community is slowly waking up to find itself in an unfamiliar Las Vegas hotel room with a throbbing headache, hazy memories of the night before, and a fresh tattoo reading "r=0.2".
