吉林大学2 0 1 2 年考博英语其中一篇阅读理解真题及答案 Astronomers have witnessed the biggest bang since the Big Bang—the moment about 15 billion years ago when the universe was created in a massive explosion.The huge burst of energy from the edge of the universe is estimated to be second only to the moment of creation in its explosive force,releasing more energy in two seconds than the sun will give out in its lifetime.Scientists hope the explosion—known as a gamma-ray burst because it emits energy in the form of gamma radiation—will shed light on the earliest stages in the evolution of the stars and galaxies.Gamma-ray bursts cannot be seen by the human eye but if they could the sky would light up like a camera flash each time they occurred.They are by far the most energetic events in the universe and,until now,have remained largely a mystery. The latest gamma-ray burst to be detected accurately occurred last December.Using a network of telescopes and satellites,the astronomers were able to calculate its distance from earth at about 15 billion light years.This means it must have happened soon after the Big Bang itself,while the intensity of the radiation revealed it to be the biggest bang recorded by man.Scientists from the American National Aeronautics and Space Administration and the California Institute of Technology are to announce details of their analysis this week.The huge distance between the source of the explosion and the Earth suggests gamma-ray bursts are up to 10 times larger than previously thought,said Jonathan Katz,professor of physics at Washington University in St Louis. “Gamma-ray bursts may be the most distant things we will ever see and as such will act as beacons to pr...
