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Cosmology

BICEP2: A Month Later

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BICEP2: A Month Later

For theoretical physicists, ambulance chasing involves getting papers out quickly after a major data release. Some ambulance chasers make significant contributions, some are just trying to draw attention to their earlier work, while others are banging out insubstantial papers in the hope that they will be cited by their slower colleagues. But whatever their motives, cosmologists have certainly been busy: the BICEP2 discovery paper has been cited 188 times on the Arxiv, all in "preprints" written within a month of the original announcement. I am pretty sure this is a world record, and you can always check the current tally.

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How To Train Your Universe

How To Train Your Universe

Cosmologists don't give tips to newbie universe-builders, but we do ask how our universe evolved. It was quickly discovered that a simple Big Bang needed special and apparently arbitrary initial conditions in order to grow into the universe we now inhabit. But In 1980, physicist Alan Guth, then a post-doc at SLAC, realised that a mechanism he dubbed inflation made these "initial conditions problems" manageable, even if it didn't solve them completely.

The Smoking Gnu

The Smoking Gnu

When it comes to the details, the stories diverge. Some claim a (relatively) large B-mode that could be hard to square with other datasets, or would imply that the early universe is weirder than we imagine. Other rumours tell of a signal that is consistent with everything else we know, but might permit only a more tentative detection.

Planck Live Blog

Planck Live Blog

Planning to live blog the Planck live blog data release tonight.  In the meantime, read Renee Hlozek and Shaun Hotchkiss's blogposts which give good discussions of what is at stake, or watch Ed Copeland giving a quick survey of cosmology.

How Two Guys Working for the Telephone Company Discovered the Origin of the Universe

How Two Guys Working for the Telephone Company Discovered the Origin of the Universe

The story has been told many times. The detector had an annoying and remarkably intransigent "hiss" and Penzias and Wilson knew it was the detector, since the hiss didn't change as they pointed their antenna at different places in the sky.  A radio hiss can be converted into a temperature: a red-hot coal has a temperature of a few thousand degrees Celsius but this hiss was microwave-hot, putting it just a few degrees above absolute zero.