Life in the Milky Way


Every year, the “Edge” website poses one particular question to about 200 thinkers. All the answers are posted on the website, and eventually published in book form. The 2016 question was: “What Do You Consider the Most Interesting Recent (Scientific) News? What Makes It Important?”

My answer to this year’s question is posted below (you can see all the answers
Figure 1. Roughly Earth-size planets in the Habitable Zone of their central star. Credit: NASA Ames/W. Stenzel.

The publication of this empirically-based estimate marked a critical point at which the quest for extrasolar life transitioned from mere speculation to an actual science. The realization that planets which could, in principle at least, support life has turned the search for extrasolar life almost into an obsession for many astronomers. The plans for the near future in this field envision a two-pronged attack. On one hand, a series of upcoming and planned telescopes (in space and on the ground) will look for biosignatures — characteristics imprinted by life processes — in the atmospheres of planets in the HZ of their host stars.

On the other, Russian billionaire Yuri Milner announced on July 20th, 2015 a $100-million decadal project (called “Breakthrough Listen”) aimed at providing the most comprehensive search for alien communication (an extension of the existing Search for Extraterrestrial Intelligence) to date.

There is little doubt that the determination of the number of planets capable of hosting life will stay news for at least a few decades. The only discovery in this domain that will eclipse these findings will be the actual detection of extrasolar life. We are, for the first time in human history, on the verge of potentially eliminating the last obstacle to Copernican modesty — life on Earth. Copernicus taught us that the Earth is not in —> Read More