The Scientific Search For Alien Existence (Rebroadcast)

Advanced technology that lets us see previously unseen parts of the solar system, combined with the frequent discovery of “Earth-like” planets, has strengthened our longstanding cultural belief that aliens could exist (not to mention the fact that extraterrestrials continue to capture our imagination at the box office). And now, there’s even more to the idea that there is life beyond our planet.

Some of the latest scientific theories supporting the existence of alien life are collected in an anthology of essays called “Aliens,” edited by theoretical physicist Jim Al-Khalili. He and a couple of contributors weigh in on why scientists are more optimistic than ever before that we’re not alone in the universe.


  • Jim Al-Khalili Theoretical physicist; editor, “Aliens: The World’s Leading Scientists On The Search For Extraterrestrial Life”
  • Adam Rutherford Geneticist; host, “Inside Science” on BBC Radio 4; author of A Brief History of Everyone Who Ever Lived: The Human Story Retold Through Our Genes
  • Nathalie Cabrol Senior research scientist at the SETI Institute and director of the Carl Sagan Center

Excerpts From The Anthology, “Aliens”

From “Where Is Everybody?” by Jim Al-Khalili:

“Of course, an alien planet being suitable for life is one thing, but the really big unknown is this: given the right conditions, how likely is it that life could evolve elsewhere? To answer is that we need to understand how life began on Earth. If we are indeed alone in the vastness of the cosmos, then we need to understand why we are so special. Why would the Universe be apparently so finely tuned for life to exist, yet harbour it in just one isolated corner?

One way of thinking about this is to ask yourself how come you exist? What were the chances that your parents would meet and produce you? Indeed, what were the chances of their parents meeting, and so on all the way back? We are each of us the culmination of a long and highly unlikely chain of events leading back to the origin of life itself. Break any one of the links in that chain and you would not be here to ask the question in the first place. Maybe our existence is really no more remarkable than the lottery winner contemplating his or her good fortune: had that sequence of numbers not come up, then someone else would have won and they would also reflect on the improbable odds of their win.

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