Cambridge Science Festival: Life in Unexpected Ways, Unlikely Places

Billions of years ago, globs of molecules sat lifeless on an inhospitable version of our future home. How did such molecules come to life? As part of the Crossroads conference last weekend, physicist and futurist Freeman Dyson shared his thoughts on the origin of life on Earth, and the forms it may take elsewhere in the universe.

In its simplest form, life on Earth is made of nucleic acids, what Dyson calls "the software," and proteins, "the hardware." The standard hypothesis of life's formation is known as the "RNA world," which suggests that because of all of the known properties of RNA today, it may have been alive billions of years ago. Dyson advocates an alternate view, the elegantly-named "garbage bag theory." As Dyson puts it, "The first primitive cells were just random collections of molecules [within a membrane], which gradually became more organized. Before long, they started competing with each other." In a known chemical pathway, it is possible to progress from metabolism to formation of RNA, which would eventually allow the bags to replicate. Through competition and selection, the process which has sustained evolution to the present day, more efficient bags came to dominate and become the first true cells.

Dyson's novel theory for life's formation on Earth carries over into a new concept of how to find it elsewhere. "I don't believe life is mostly on planets," he stated boldly. "Life may originate on planets, but it has probably spread to other places by now, and the number of places where it's spread has no relation to the number of places where it's originated." Therefore, he believes our searches for life, which have mostly gone in a very systematic way--first, find planets like Earth, then find which of these quasi-Earths have life--may be missing the diversity of life strewn haphazardly throughout our galactic neighborhood. Instead, we should be looking for life that we would be easily (and cheaply) be able to see, even if it is unlikely to be there.

"The whole history of astronomy is finding things which aren't supposed to be there." So what form would Dyson's "unexpected" life take? As an example, he took us to Europa, a moon of Jupiter with water ice on the surface covering a liquid ocean below. Most visions of Europan life have assumed it would be in the relatively warm ocean, but Dyson suggests we scan the surface. He envisions "flowers" taking nutrients from the ice, whose "petals" must concentrate sunlight much more efficiently than plants on Earth.

Dyson's flowers would have to adapt to life in a vacuum. While this may seem difficult at first, the prospect of airless life is essential to his belief that life can spread far from its origin. "Why is it better to be in a vacuum? Because you can move! If something hits Europa and sends big chunks of ice up into space, any living creatures that are attached to them can continue more or less as before." The floating, flowery ice chunks would careen through space, sustaining life as they are, or crashing onto another world and rooting flowers on a new home.

When we first discover life on another world, what form will it take? How will it have originated? An open mind is a great asset. While the ideas Dyson presented at the conference seem to stretch our view of what is possible, "we never have as much imagination as nature."

If you're interested in Dyson's flowers, check out this article by Rachel Courtland of New Scientist, who explored the topic in more detail earlier this week.