Artist’s conception of a planetary lineup that shows habitable-zone planets with similarities to Earth: from left, Kepler-22b, Kepler-69c, Kepler-452b, Kepler-62f and Kepler-186f. Last in line is Earth itself. Credits: NASA/Ames/JPL-Caltech

The question of whether we are alone in the universe is one of the most intriguing questions in science and astronomy. The answer to ‘are we alone?’ affects our claim for being special in the cosmos, and we shall never know – unless we search.

Gresham College invited Joseph Silk to talk about whether we are alone in the universe. Silk is a British astrophysicist. He studied at Cambridge, earned his Ph.D. from Harvard in 1968, was a postdoctoral fellow at Cambridge and Princeton, and taught at the University of California, Berkeley, and the University of Oxford.

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Our solar system formed half way through the history of the universe, and many sun-like stars that host planetary systems are billions of years older than our Sun. The odds of finding evidence for life are unknown, but the search continues as astronomers observe the nearby universe for Earth-like planets and seek signs of life on exoplanets that resemble the earth in terms of atmosphere, composition, and climate.