The John D. Mackay Memorial Lecture

Is life unique to Earth and found nowhere else amongst an estimated 40 billion planets in our galaxy? Or is it ubiquitous throughout the galaxy as well as among the many billions of other galaxies in the observable universe? Some astronomers have argued that life is a fundamental feature of the universe, among them Prof. Chandra Wickramasinghe and the late Sir Fred Hoyle. In a collaboration of over 40 years they developed the theory of cometary panspermia: the idea that life is widespread, dispersed in cosmic dust and gas clouds and spread to planets by comets and meteorites.

Over the decades evidence to support the theory came first from discoveries of unexpectedly complex organic molecules in space as well as in comets. There has also been the discovery of conditions within comets that could provide ideal sites for replication of bacteria. There is geological evidence of the oldest bacteria in rocks dated older than 4.2 billion years during a period of violent impacts by asteroids and comets, suggesting that they came with impacting comets.

Evidence within biology itself has shown that evolution of life has involved the additions of viral sequences that most plausibly came from space. There are discoveries too of the space-hardiness of bacteria, and of bacteria themselves in the stratosphere and on the outside of the international space station – consistent with the continuing ingress of these biological entities from space.

So why is it that the theory is not yet widely accepted in physics or biology? The reason, argues Prof. Wickramasinghe, now an Honorary Professor at the University of Buckingham, is connected with cultural issues more than science, and he joins us to put forward the case for the theory.

You can watch this free event from here, through the YouTube link below, or if you’d like to join questions and discussion, you can also go to the Science Festival’s YouTube channel