Think of beautiful blue planets with endless oceans orbiting many of the Milky Way’s one trillion stars. Could they support life? Perhaps even intelligent life? “There may be life there,” says Lisa Kaltenegger of the Max Planck Institute for Astronomy and the Harvard-Smithsonian Center for Astrophysics. “But could it be technology-based like ours? Life on these worlds would be under water with no easy access to metals, to electricity, or fire for metallurgy. Maybe life’s inventiveness to get to a technology stage will surprise us.”
In 2016, Kepler astronomers discovered planets are unlike anything in our solar system –a “water world” planetary system orbiting the star Kepler-62. This five-planet system has two worlds in the habitable zone — their surfaces completely covered by an endless global ocean with no land or mountains in sight.
Could alien waters worlds at some point evolve life as we know it on Earth? “Purely ocean worlds (without land on the surface),” writes Avi Loeb, chairman of Harvard’s astronomy department in an email to dailygalaxy.com, “are not likely to develop the diversity of life as we know it because they will be depleted of essential nutrients for life, such as phosphorous and molybdenum.”
“We typically think having liquid water on a planet as a way to start life, since life, as we know it on Earth, is composed mostly of water and requires it to live,” explains astrophysicist Natalie Hinkel of Vanderbilt University. “However, a planet that is a water world, or one that doesn’t have any surface above the water, does not have the important geochemical or elemental cycles that are absolutely necessary for life.”
“I think it could be dangerous just thinking about everything in an Earth-mindset,” says Ramses Ramirez at the Tokyo Institute of Technology. “You might be missing out on other possibilities.”
New research suggests that about 35% of all known exoplanets which are bigger than Earth should be water-rich. The newly-launched TESS mission will find many more of them, with the help of ground-based spectroscopic follow-up. The next generation space telescope, the James Webb Space Telescope, will hopefully characterize their atmospheres with important implications for the search of life in the Milky Way.
“It was a huge surprise to realize that there must be so many water-worlds”, said lead researcher Dr Li Zeng (Harvard University).
“If there is magic on this planet,” wrote one of Earth’s great philosopher’s of science, Loren Eiseley in The Immense Journey, “it is found deep within in its vast blue oceans.
The oceans of Earth itself became the conduit for evolution, says Peter Godfrey-Smith in Other Minds. Earth’s ocean-dwelling cephalopods – octopuses, squids and nautiluses, Godfrey-Smith writes – “are an island of mental complexity in the sea of invertebrate animals”, he writes, having developed on a different path from us, “an independent experiment in the evolution of large brains and complex behavior.”
“If we can make contact with cephalopods as sentient beings, it is not because of a shared history, not because of kinship, but because evolution built minds twice over,” says Godfrey-Smith. “This is probably the closest we will come to meeting an intelligent alien.”
The Daily Galaxy via Arizona State University, Goldschmidt Conference, The Atlantic, and Scientific American
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