According to the Daily Telegraph, Howard Smith, a senior astrophysicist at Harvard University, says he believes humans are alone in the universe. His belief is based on the analysis of 500 discovered planets that appear to be too hostile to support life—at least as it is currently known.
Smith is likely not alone in his belief, but other scientists continue to search for life elsewhere in the universe. It was less than two months ago when NASA announced the discovery of a bacteria capable of surviving in an arsenic-heavy environment by modifying its cells. The geomicrobiologist who led the study of this bacteria explained that this discovery “open[ed] the door for us to think about biology in ways we have never thought.” So Smith might be overhasty with his dismissal of those 500 planets with environments hostile to “life as we know it.”
One should hope that a senior astrophysicist would be open-minded enough to speculate that unknown life on unknown planets just might have biology that differs from what is known on Earth.