Scientists propose why we cannot find life in space
10 Aug 2016 by qwwqdccwwm.d qwwqdccwwm.d
The reason why we cannot find other life outside of Planet Earth is because we may be ahead of the evolutionary curve, according to scientists from the Harvard Smithsonian Center for Astrophysics.
The reason we cannot find other life outside of Planet Earth is because we may be ahead of the curve, according to scientists from the Harvard Smithsonian Center for Astrophysics.
The universe is 13.8bn years old, with Earth forming less than five billion years ago. One school of thought among scientists is that there is life billions of years older than us in space. But this recent study in the Journal of Cosmology and Astroparticle Physics argues otherwise.
Avi Loeb, lead author from the Harvard Smithsonian, said: “If you ask, 'When is life most likely to emerge?' you might naively say, 'now'. But we find that the chance of life grows much higher in the distant future."
Life first became possible 30m years after the Big Bang, when stars first provided the universe with enough carbon and oxygen. Life is predicted to end in 10 trillion years when all the stars in the universe have faded and died. Loeb and a team of researchers considered the likelihood of life between those two parameters.
They concluded the main factor would be the lifetime of stars. Stars larger than approximately three times the Sun’s mass will perish before life has a chance to evolve. This is because the higher a star’s mass the shorter its lifetime. The smallest stars weigh less than a tenth as much as the sun and will glow for 10 trillion years, meaning life has lot of time to begin on those planets orbiting them in the ‘habitable zone’. The probability of life increases over time so the chance of life is many times higher in the distant future than now.
Loeb said: “So then you may ask, why aren't we living in the future next to a low-mass star? One possibility is we're premature. Another possibility is that the environment around a low-mass star is hazardous to life." This is because red dwarfs emit strong flares and ultraviolet radiation that would strip any atmosphere from a rocky planet in the habitable zone.
Future space missions such as the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope will help Loeb answer the questions of whether our existence is premature and if low-mass stars are hazardous.
