Space & Astronomy

90% of galaxies may be hostile to life

By T.K. Randall
November 25, 2014 ·  36 comments

Gamma ray bursts are destructive and deadly. Image Credit: NASA/ESA/ESO The universe contains an estimated 100 billion galaxies, a seemingly endless supply of opportunities for life to develop, yet according to astrophysicists Tsvi Piran and Raul Jimenez only one in ten of these may be able to accommodate complex life forms like those we see here on Earth.

The reason for this is that long gamma ray bursts, which occur when massive stars collapse and explode, can set off a chain reaction capable of destroying a planet's ozone layer.

The two scientists believe that in most galaxies these bursts would make it extremely difficult for life forms more complex than microbes to develop. Even in galaxies such as our own where the size and metallicity make conditions more favorable, there is still the likelihood that these bursts could render most of the planets similarly inviable, especially those nearer to the center.There is even evidence that a mass extinction event that occured on Earth 450 million years ago that wiped out 80% of all species may have been caused by one of these gamma ray bursts.

"It's almost certain that bacteria and lower forms of life could survive such an event," said physicist Brian Thomas. "But [for more complex life] it would be like hitting a reset button."

"You'd have to start over from scratch."

Source: Sciencemag.org | Comments (36)

Tags: Life, Universe, Galaxy, Gamma Ray Bursts