Monthly Archives: December 2004

The Mysterious Flashes

 

      In the late 1960s the US military satellites started looking for gamma radiation suspecting secret Soviet nuclear tests. But instead of finding gamma radiation from Russia they found flashes of gamma radiation from outer space. These flashes were very intense and lasted a very short duration. Scientists named these flashes Gamma Ray Bursts.

      At first scientists thought that Gamma Ray Bursts(GRBs) orignate from our own galaxy( Milky Way). But when more GRBs were detected they seemed to come from all possible directions. So the theory that they orignate from the Milky way was rejected. They come from all possible directions in the Universe.

 

      The radiation from GRBs is VERY VERY intense. It can be hundreds of times the light produced from a typical supernova( blast at the end of a star’s existance). A typical GRB can be a million trillion times brighter than the Sun. This makes a GRB the brightest source of gamma ray photons as long as it lasts.

      GRBs are very common. Since 1991 more than 2500 GRBs have been detected.

      In 1997 scientists got some data about the location of a GRB. But they were shocked to discover that the particular GRB was more than 12 billion light years away!!! So it had occurred 12 billion years back and light has reached us now. That means that whatever event caused that GRB occurred when our earth was just born.

      If a GRB occurs in our Galaxy it would most likely kill us by the intense radiation. It will turn night into a day of intense and blinding light!

      GRBs are classified into two types: short duration( lasting less than 2 seconds) and long duration( lasting more than 2 seconds). The radiation of these two is very different and scientists suspect that they may be caused by different kinds of events.

      One theory is that long duration GRBs are caused by hypernovae: the huge explosion caused when a special type of star( Wolf-Raylet) star dies. A Wolf-Raylet star is a very heavy, very hot star that sometimes produces fits of material ejection. When such a star collapses the collapsing core sends a blast wave through the star at speeds close to the speed of light. This blast wave hits material inside the star and produces huge amount of light and gamma rays. These come to us as Gamma Ray Bursts. A hypernova explosion can be hundreds of times more violent then a supernova.

      Another theory that tries to explain short duration GRBs proposes that such GRBs are produced when neutron stars collide and annihilate each other. Neutron stars and very dense stars that have atoms stripped of everything except their nucleus.

      But no one knows for sure. What I can say for sure is that the earth may be a violent place but the violence on earth is NOTHING compared to the violence in the Universe. And when we look at the Universe we realize our smallness and the trivilality of our concerns.

 

      “When men are calling names

       and making faces

       And all the world is ajangle and ajar

       I meditate on inter-stellar space

       And smoke a mild cigar”

                        -Bert Taylor

 

 

Kanwar

 

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  Go, wondrous creature! mount where Science guides:                 

  Go, measure earth, weigh air, and state the tides:                  

  Instruct the planets in what orbs to run,                          

  Correct old time and regulate the Sun;                             

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