Seeing the birth of the universe in an atom of hydrogen

September 5, 2012, Tel Aviv University
Seeing the birth of the universe in an atom of hydrogen

Windows to the past, stars can unveil the history of our universe, currently estimated to be 14 billion years old. The farther away the star, the older it is—and the oldest stars are the most difficult to detect. Current telescopes can only see galaxies about 700 million years old, and only when the galaxy is unusually large or as the result of a big event like a stellar explosion.

Now, an international team of scientists led by researchers at Tel Aviv University have developed a method for detecting galaxies of stars that formed when the universe was in its infancy, during the first 180 million years of its existence. "The method is able to observe stars that were previously believed too old to find," says Prof. Rennan Barkana of TAU's School of Physics and Astronomy.

Published in the journal Nature, the researchers' method uses to seek out emitted by , which were abundant in the early days of the universe. Emitting waves measuring about eight inches (21 centimeters) long, the atoms reflect the radiation of the stars, making their emission detectable by radio telescopes, explains Prof. Barkana. This development opens the way to learning more about the universe's oldest galaxies.

Reading signals from the past

According to Prof. Barkana, these waves show a specific pattern in the sky, a clear signature of the early galaxies, which were one-millionth the size of galaxies today. Differences in the motion of and gas from the early period of the universe, which affect the , produce a specific pattern that makes it much easier to distinguish these early waves from bright local .

The intensity of waves from this early era depends on the temperature of the gas, allowing researchers to begin to piece together a rough map of the galaxies in an area of the sky. If the gas is very hot, it means that there are many stars there; if cooler, there are fewer stars, explains Prof. Barkana.

These initial steps into the mysterious origins of the universe will allow radio astronomers to reconstruct for the first time what the early universe looked like, specifically in terms of the distribution of stars and across the sky, he believes.

A new era

This field of astronomical research, now being called "21-centimeter cosmology," is just getting underway. Five different international collaborations are building radio telescopes to detect these types of emissions, currently focusing on the era around 500 million years after the Big Bang. Equipment can also be specifically designed for detecting signals from the earlier eras, says Prof. Barkana. He hopes that this area of research will illuminate the enigmatic period between the birth of the universe and modern times, and allow for the opportunity to test predictions about the early days of the universe.

"We know a lot about the pristine universe, and we know a lot about the universe today. There is an unknown era in between when there was hot gas and the first formation of stars. Now, we are going into this era and into the unknown," says Prof. Barkana. He expects surprises along the way, for example involving the properties of early stars, and that observations will reveal a more complicated cosmological reality than was predicted by their models.

Explore further: Stars in the making: Research may sharpen view of developing universe

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2.3 / 5 (9) Sep 05, 2012
The "dark" ages of cosmology continues, our descendants are going to laugh at the folly of our ignorance. Much as we do towards the flat earthers and epicyclians.
not rated yet Sep 06, 2012
Of course we don't know everything yet. But it is ironic and/or erroneous to call cosmology "the "dark" ages" a decade after the first, and then likely last within its area of validity, self-consistent cosmology was found, the standard cosmology. It is the general relativity of our day.

Similarly to how everyday physics is now completely known in its outlines, the everyday cosmology is now completely known in its outlines.
not rated yet Sep 07, 2012
Speaking of ignorance... the writer of the article:
"Current telescopes can only see galaxies about 700 million years old" instead of:
"galaxies when the universe was about 700 million years old"
5 / 5 (1) Sep 07, 2012
The "dark" ages of cosmology continues, our descendants are going to laugh at the folly of our ignorance. Much as we do towards the flat earthers and epicyclians.

And what do you think SHOULD happen? That we jump from no knowledge to full knowledge through some miraculous way? Magic? Belief?

Most certainly future generations will see things differently - that doesn't mean the previous knowledge was wrong (e.g. you CAN model the universe using epicycles and it would be as correct as using Newtonian motion. The laws would just be humongously more complicated to write down. And they would still be a good approximation for a realtivistic universe.)

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