Life in the universe | The EconomistDoes life exist anywhere else in the universe? And how did it get started? Scientists are seeking the answers in the cosmos, our solar system and right here on planet Earth.
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Is there life elsewhere in the universe? Anyone who has pondered the immensity of the cosmos has probably wondered at some time or another whether life exists beyond our planet?
The search for life beyond Earth has been buoyed by recent discoveries made by NASA's Kepler telescope - it's looking for planets outside our solar system known as exoplanets. Kepler measures the brightness of distant stars and tracks a stars dimming when a planet passes in front. Up until 1995, exoplanets were purely theoretical - but scientists have since identified thousands of them.
in July, NASA scientists announced the discovery of one of their most exciting exoplanets yet - Kepler-452B. Located some fourteen thousand light-years away the planet is in the habitable zone which means it's the right distance from its own Sun and also the right size to potentially be earth-like.
There is a limit to how much we can learn about Kepler-452B because of its distance. NASA is launching the James Webb telescope in 2018 to find earth-like planets closer to home so they can study their atmospheres for bio signatures that would indicate the presence of life. But there's another way to learn more about distant planets beyond what the Kepler telescope can tell us, and that is to look for signs of intelligent life.
Frank Drake has been listening out for signals of intelligent life elsewhere in the universe for over 50 years. Mr Drake came up with something called the Drake Equation which is a mathematical formula that estimates how many advanced civilizations capable of transmitting signals might exist in the universe. He co-founded the SETI Institute, the search for extraterrestrial intelligence. Scientists at the SETI Institute have been searching for intelligent life for the past few decades.
SETI researchers have not come across any signals yet but they say this is to be expected. SETI's efforts recently got a huge boost with a launch of breakthrough Listen, overseen by Martin Rees, Stephen Hawking, and Frank Drake and funded by Silicon Valley entrepreneur Yuri Milner. The project will greatly expand the organization's capacity to search and sift through data. But scientists aren't only interested in discovering life forms light-years away. At first glance our solar system seems like a rather unlikely place to find life beyond Earth but the reason scientists think it is plausible is because of the discovery of a group of organisms called extremophiles that live on earth.
Scientists are looking at the moons of Jupiter and Saturn as well as our nearest neighbor Mars. The hope is that if we find further life in our solar system on places like Mars, we will improve our understanding of how easily it might have started elsewhere. But there is another way to answer this question - determining how it started on earth.
One man who is trying to come up with an answer to this question is Jack Szostak. In his lab at Harvard University he's trying to determine how easy it is to create life by making it himself. Modern cells are intricate nano scale factories stuffed with thousands of different chemicals each taking part in a complicated and messy web of reactions. Long strands of DNA and codicils genetic information. Shorter strands of RNA carry that information around the cell telling it how to manufacture the proteins that run the chemical reactions it requires to live. It seems unlikely that these systems all evolved at the same time. At the Szostak lab they're focused on two experiments. One to work out how primitive cell membranes could grow and divide into daughter cells, and the other on RNA replication.
Dr Szostak and his team have already created a protocell from a blob of lipids which contains RNA. The sticking point at the moment is working out how to make RNA that can copy itself without relying on a helping hand from RNA enzymes. If it is a difficult process reliant upon various bits of luck or circumstance then it is possible that we are a cosmic fluke - one that isn't going to be repeated elsewhere. But if experiments like Dr Szostak show that life emerges easily, then the odds of life appearing elsewhere in the universe look more likely.
Perhaps one day when we're looking into the night sky we'll finally know the answer to the question are we alone?