View Full Version : Shadows of primordial atoms

2004-May-05, 04:09 PM
Scientists See Through the Dark Ages of the Universe (http://www.spaceref.com/news/viewpr.html?pid=14154)

Astronomers who want to study the early universe face a fundamental problem. How do you observe what existed during the "dark ages," before the first stars formed to light it up? Theorists Abraham Loeb and Matias Zaldarriaga (Harvard-Smithsonian Center for Astrophysics) have found a solution. They calculated that astronomers can detect the first atoms in the early universe by looking for the shadows they cast.

To see the shadows, an observer must study the cosmic microwave background (CMB) - radiation left over from the era of recombination. When the universe was about 370,000 years old, it cooled enough for electrons and protons to unite, recombining into neutral hydrogen atoms and allowing the relic CMB radiation from the Big Bang to travel almost unimpeded across the cosmos for the past 13 billion years.

Over time, some of the CMB photons encountered clumps of hydrogen gas and were absorbed. By looking for regions with fewer photons - regions that are shadowed by hydrogen - astronomers can determine the distribution of matter in the very early universe.

"There is an enormous amount of information imprinted on the microwave sky that could teach us about the initial conditions of the universe with exquisite precision," said Loeb.

2005-Oct-21, 11:37 AM
Intriguing, examining the early Universe by looking at shadows.......... Very intriguing.

2005-Oct-21, 07:31 PM
There is a Lovecraft pastiche in there somewhere.

Ken G
2005-Oct-22, 03:16 AM
George Rybicki looked at this question a long time ago, and decided it just wasn't a feasible idea. I wonder what Loeb and company are seeing that he didn't? I think he was talking about spectral features, while Loeb seems to be talking about an angular imprint, maybe that's the issue.