The earliest structures in the universe may be visible by the shadows they cast in the afterglow of the big bang.
The objects have been hidden until now because they formed in the dark age of the universe before the first stars switched on. "The shadows promise to provide the richest ever gold mine of information about the early universe," says Abraham Loeb of Harvard University.
The so-called cosmic dark age stretched from the fading of the big bang fireball 13.7 billion years ago to the time when the first stars ignited, several hundred million years later. During this period, hydrogen clouds formed into structures that eventually became the stars and galaxies of today.
Astronomers would dearly like to understand this formation process but, because of the lack of light, this period of the universe's history has seemed impenetrable - until now.
Loeb and his Harvard colleague Matias Zaldarriaga think that the hydrogen gas must have absorbed radiation left over from the big bang and that this absorption would have created shadows that astronomers should be able to see today. The effect is similar to that of a terrestrial cloud blotting out the sun and casting shadows on the ground.
More: http://www.newscientist.com/news/news.jsp?id=ns99995014
The objects have been hidden until now because they formed in the dark age of the universe before the first stars switched on. "The shadows promise to provide the richest ever gold mine of information about the early universe," says Abraham Loeb of Harvard University.
The so-called cosmic dark age stretched from the fading of the big bang fireball 13.7 billion years ago to the time when the first stars ignited, several hundred million years later. During this period, hydrogen clouds formed into structures that eventually became the stars and galaxies of today.
Astronomers would dearly like to understand this formation process but, because of the lack of light, this period of the universe's history has seemed impenetrable - until now.
Loeb and his Harvard colleague Matias Zaldarriaga think that the hydrogen gas must have absorbed radiation left over from the big bang and that this absorption would have created shadows that astronomers should be able to see today. The effect is similar to that of a terrestrial cloud blotting out the sun and casting shadows on the ground.
More: http://www.newscientist.com/news/news.jsp?id=ns99995014
