By: Sara Knight
BU News Service

Astrobiologist Jack T. O’Malley-James and his team detailed their efforts to predict how life on Earth will end in the beautifully titled study “Swansong Biospheres.” Despite appearances, their end goal is not to depress us with a reminder of mortality and the non-permanence of everything we know and love. Rather, they seek to know what might happen to life here to know what to look for on similar but older worlds out there.

Our sun’s gradual warming and eventual exhaustion of nuclear fuel sets off the ticking clock in the background of the study. One day, the sun will find itself with no more core hydrogen to burn and will be so bummed-out it will collapse in on itself in disappointment (or because of gravitational attraction, maybe). By contracting, the sun will pull in more hydrogen to its center, setting off a rapid chain of reactions – increasing its luminosity and sparking a great expansion. It is at this point our sun evolves from a cute yellow dwarf into a mature red giant. Scientists mark this graduation date occurring anywhere from 5 billion years to 7.6 billion years in the future.

According to O’Malley-James et al. life will already be several billion years extinct by that point. They estimate that the hardiest unicellular life-forms will be able to cling on to our increasingly blistering planet only up to 2.8 billion years in the future, and then only in the highest latitude regions in caves of ice.

This knowledge allows us to search for life on Earth-like planets at different phases of their evolution. O’Malley-James explained to National Geographic: “A planet in a later stage of its habitable development may appear uninhabited if we only look for the signs of life as we know it on Earth today.”

More Great Information on the End of the World and/or Humanity:

If you are of an apocalyptic bent and 2.8 billion years seems like too long to wait, don’t despair! It really could happen any day now – visit one of the internet’s best websites, Exit Mundi, to read all the different dire scenarios in which our species bows out, or blows out, or fizzles out, or whatever. The site kindly organizes the scenarios either by time (any day now, near future, or distant future) or by category (space, earth, science, religion).
Be warned: Exit Mundi is a huge time-sink, and we may not have all that long left.