The World’s End

Image from Wikimedia Commons.
Image from Wikimedia Commons.

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:

Image from Wikimedia Commons.
Image from Wikimedia Commons.

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.

Life might survive a meteoric fall to Earth

Phytoplankton: foundation of the ocean's food web...and possibly of life's origins? Photo courtesy of NOAA via flickr Creative Commons.
Phytoplankton: foundation of the ocean’s food web…and possibly of life’s origins? Photo courtesy of NOAA via flickr Creative Commons.

by Mark Zastrow
BU News Service

Are we the aliens we’ve been looking for?

The notion that the seeds of life originated in outer space and fell to Earth on a meteorite may seem like science fiction. After all, the theory, known as panspermia supposes that life could survive the violent impact. But now, that survival act looks possible, according to research presented last month at a conference in London.

To test life’s resilience, the researchers froze phytoplankton—the microscopic organisms that permeate the ocean—into pellets, as if stuck on a rock sailing through interstellar space. They loaded the ice-bound algae into a powerful gas gun, which shot them into water at over 13,500 miles per hour. Then they thawed the samples and left them to culture.

But despite the violent impact, a small portion of plankton survived. “This sort of impact velocity would be what you would expect if a meteorite hit a planet similar to the Earth,” Dina Pasini, a scientist at University College London and the study’s lead author, said in a statement.

Panspermia has recently received a boost of media coverage. A study published September 15 in the journal Nature Geoscience suggested that comets smashing into primordial Earth could have formed amino acids, the building blocks of life. And in late August, a team of scientists claimed that Mars, not Earth, was the best place in the early Solar System to find molybdenum, a key element in enzymes required by complex life.

Pasini notes that a round of headlines doesn’t mean the theory is proven. But she says that her research shows that questions like whether we fell from the sky, or if aliens out there are our distant relatives, are “not as farfetched as one might assume.”