Two indispensable questions about life in the Cosmos

How did life on Earth initiate? Is there life thriving on other worlds? An answer to either question will reflect very heavily on the other.

These two above mentioned questions have an outstanding pedigree as human beings have been asking them since time immemorial. What is extraordinary about this historical moment, though, is how close we might be to answering either one. Even more extraordinary is the reality that an answer to either of these momentous questions will reflect very heavily on the other.

‘Is Earth Exceptional’ is a new book that purposely takes on these two questions at once: the beginning of life on Earth and the search for life outside Earth. The coupling of the issues into a single linked set of explorations is not a conceit or a astute form of packaging. Written by astronomer Mario Livio and biochemist Jack Szostak, what this significant new book offers is a deep dive into the rapidly evolving science associated with each question — and an equally deep conciliation on how they each play off each other.

Is Earth exceptional?

Early on in the book, authors introduce the crucial “ZOI principle,” which stands for Zero-One-Infinity. At the heart of our questions about life in the Cosmos is a basic question about probabilities: How likely is it to get life initiated on a random planet where the conditions don’t exclude its emergence (conditions like lack of atmosphere or being too hot or too cold)? If the basic material building blocks for life are there, then what is the likelihood that what occurred on Earth some 3.5 to 4 billion years ago will occur elsewhere?   

The Z part of the ZOI principle stands for Zero. Is it probable that what occurred on Earth was, essentially, a one-off? Was it a cosmic accident with a likelihood of, essentially, zero? That would effectively mean the origin of life never occurs anywhere else. People who don’t study the problem often balk at this prospect. After all, there are so many potentially habitable planets in the Cosmos, (the number is believed to be 10 billion trillion), so assuredly what happened here must have happened elsewhere. If the odds of initiation of life on a randomly chosen and potentially habitable planet are less than one in 10 billion trillion, then the Cosmos simply runs out of planets. The Earth will be stunningly unique because our planet just got stunningly lucky.

Then, however, there is the OI, or “One-Infinity,” part of the same ZOI principle. This is the idea that if you found even one other independent instance of life in the Cosmos beyond Earth, you could practically say there must be many others out there beyond your single discovery. Finding even one planet with “alien” life would, in other words, be enough to assume our Universe is teeming with alien life.

So, how near are we to finding alien life? This is Mario Livio’s domain. A theoretical astrophysicist of extensive interests and immense talent, Livio is the expert to talk with if you desire to know about the science of astrobiology and its hunt for life on other worlds. Pairing of Szostak and Livio and their particular specialties makes Their book ‘Is Earth Exceptional’ such a joy to read. It takes the reader deep into the frontiers of both the beginning of terrestrial life and the astrobiological endeavour for extra-terrestrial life.