See Inside Scientific American Volume 311, Issue 2

Whispers from Creation

The recent discovery of gravitational waves emerging from the big bang may point a way forward

DARK POLE: Telescopes at the South Pole search for clues about the universe's first moments.


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Apart from the terrible weather hanging around from an unusually cold winter, the second week of March started like any other week. But then rumors started floating around in the cosmology community about an imminent announcement out of the Harvard-Smithsonian Center for Astrophysics. The rumors spread to Facebook, Twitter and the blogosphere by the weekend. Details began to emerge. This was not any ordinary announcement but rather the kind that, if correct, would happen once per lifetime. It was something that most of us dreamed we could see only in a few decades if we were lucky, if at all.

On Monday, March 17, 2014, BICEP-Keck collaboration, which operates an array of microwave telescopes located at the geographical South Pole, announced the discovery of patterns in the polarization of the cosmic microwave background that could have been generated in the early universe. If this interpretation of the observations is correct, it could confirm a 30-year-old prediction of the cosmic inflation theory: that the simplest models of inflation can generate an observable level of gravitational waves, comparable to density or temperature fluctuations in the early universe. It would also be our first direct evidence for the quantum nature of gravity, the most outstanding puzzle in theoretical physics over the past century.

Yet in science, as in life, things are rarely as simple as they first appear. For example, the simple inflationary models that predict observable levels of gravitational waves also suggest that hints of these waves should have been seen in the temperature fluctuations observed by the European Space Agency's Planck satellite. But they were not! Furthermore, microwave emission from dust in our galaxy tends to be polarized, which could confuse BICEP-Keck observations, at least to some extent.

What does all this mean for our holographic theory of the big bang? When it comes to the observations of the early universe, we are limited to a handful of (now seemingly contradictory) probes. The Planck team is expected to release additional data in October, and other teams will also weigh in soon. Reconstructing the first moments of the universe is difficult business. Only with time—and perhaps some luck—will we know how it all began.

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