Robert H. Gray
In 2016, Gray published an article in "Scientific American" about the Fermi paradox, which claims that if extraterrestrials existed, we would see signs of them on Earth, because they would certainly colonize the galaxy by interstellar travel. Gray argues that the Fermi paradox, named after Nobel Prize-winning physicist Enrico Fermi, does not accurately represent Fermi's views. Gray states that Fermi questioned the feasibility of interstellar travel, but did not say definitively whether or not he thought extraterrestrials exist.
Fermi paradox
Exoplanet detection and classification is a very active sub-discipline in astronomy, and the first possibly terrestrial planet discovered within a star's habitable zone was found in 2007. New refinements in exoplanet detection methods, and use of existing methods from space (such as the Kepler Mission, launched in 2009) are starting to detect and characterize Earth-size planets, and determine if they are within the habitable zones of their stars. Such observational refinements may allow us to better gauge how common potentially habitable worlds are.