Edo Berger got an alert early last Thursday morning when a satellite detected a 10-second blast of energy known as a gamma ray burst coming from outer space.
Telescopes around the world swiveled to focus on the explosion, soon picking up infrared radiation, which travels more slowly than gamma rays. Berger waited for the visible light which he expected to come next. It never arrived. “We were kind of blown away. We immediately knew what that meant,” Berger said. What it meant was that he was looking at the oldest thing ever spotted — an enormous star exploding 13 billion years ago. “At that point the age of the universe was only 600 million years,” he said. In other words, Berger said, he was looking “95 percent of the way back to the beginning of time.” The star which exploded was 30 to 100 times larger than our own sun, and when it died, it gave off “about million times the amount of energy the sun will release in its entire lifetime,” Berger told CNN by phone from Harvard University, where he is an assistant professor of astronomy. Its death throes produced so much energy that “momentarily, we can essentially see it anywhere in the universe,” Berger said. The object, known as GRB 090423, is about 200 million years older than the previous record-holder for oldest object ever seen. Berger isn’t just interested in the record books, though — the gamma ray burst extended the frontiers of human knowledge about the history of the universe.
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“We learn that already massive stars were around 600 million years after the universe formed,” Berger said. “We suspected that, but now we have proof. Now that we know these objects are so bright, in the next few years we should be able to pinpoint exactly at what stage in the evolution of the universe stars and galaxies formed.” “There are theories” about when that happened, Berger said, “But they are all over the place. People let their imaginations run wild.” Given the discovery last week — which was announced Tuesday — Berger thinks it is possible that he will soon have a clear answer. “If we talk in a few years, hopefully I would be able to tell you exactly when that happened,” he said. The gamma radiation from GRB 090423, which took 13 billion years to reach earth, was detected by a NASA satellite called Swift. The infrared radiation was detected by the Gemini Observatory in Hawaii.
