Ever since man began to think, two questions have been haunting him.One of them is how did it all begin ,and the other- how will it end.Though man is still searching for the answers ,it seems the answers remain ever elusive.Even today nobody knows for exact how life began on earth and how would it end.
Talking about the how-will-it- end question,I keep coming across many theories now and then ,that suggest the possible ways .From nuclear warfare to global warming and an asteroid hitting the earth ,there are numerous possibilities of ending life on planet Earth.The most recent of these that I came across is the gamma ray burst.
A gamma ray burst is the most powerful explosion known.Discovered in the 1960's,gamma ray bursts are random ,fleeting and can occur anywhere in the sky.Locating them is an irritating task!!Gamma ray bursts can be either short or long .A long gamma ray burst usually lasts for two seconds and a short gamma ray burst for a few milliseconds.But the energy released in this short span of time is enormous.
Several studies in the past have demonstrated how longer high-energy
radiation bursts, such as those caused by supernovae, and extreme solar
flares can deplete stratospheric ozone, allowing the most powerful and
damaging forms of ultraviolet radiation to penetrate to the Earth’s
surface. The probability of an event intense enough to disrupt life on
the land or in the oceans becomes large, if considered on geological
timescales. So getting a handle on the rates and intensities of such
events is important for efforts to connect them to extinctions in the
fossil record.
According to astrophysicist Brian C.Thomas of Washburn University ,a short gamma-ray burst is more significant than a long gamma-ray burst.And if such a burst occurs inside our galaxy the effects on our atmosphere and oceans could be enormous.
The first effect is to deplete the ozone layer by knocking free
oxygen and nitrogen atoms so they can recombine into ozone-destroying
nitrous oxides. These long-lived molecules keep destroying ozone until
they rain out.
Those effects are likely to have been devastating for many forms of
life on the surface -- including terrestrial and marine plants which
are the foundation of the food web.
Based on what is seen among other galaxies, these short bursts, it
seems that they occur in any given galaxy at a rate of about once per
100 million years. If that is correct, then it’s very likely that Earth
has been exposed to such events scores of times over its history. The
question is whether they left a calling card in the sky or Earth’s
geological record.
One probable evidence could be iron-60 ,the isotope that's often regarded as the possible proxy for radiation events.If isotopes like iron-60 can reveal the strata of the events, it then
becomes a matter of looking for extinction events that correlate and
seeing what died and what survived -- which could shed more light on
the event itself.
Since the idea is pretty new it hasn't found acceptance among many paleontologists. But astrophysicists are confident about their claims.