In this Friday Evening Discourse at the Royal Institution, Professor Jim Al-Khalili explores how the mysteries of quantum theory might be observable at the biological level. Although many examples can be found in the scientific literature dating back half a century, there is still no widespread acceptance that quantum mechanics -- that baffling yet powerful theory of the subatomic world -- might play an important role in biological processes. Biology is, at its most basic, chemistry, and chemistry is built on the rules of quantum mechanics in the way atoms and molecules behave and fit together. As Jim explains, biologists have until recently been dismissive of counter-intuitive aspects of the theory and feel it to be unnecessary, preferring their traditional ball-and-stick models of the molecular structures of life. Likewise, physicists have been reluctant to venture into the messy and complex world of the living cell - why should they when they can test their theories far more cleanly in the controlled environment of the physics lab? But now, experimental techniques in biology have become so sophisticated that the time is ripe for testing ideas familiar to quantum physicists. Can quantum phenomena in the subatomic world impact the biological level and be present in living cells or processes - from the way proteins fold or genes mutate and the way plants harness light in photosynthesis to the way some birds navigate using the Earth's magnetic field? All appear to utilise what Jim terms "the weirdness of the quantum world". The discourse explores multiple theories of quantum mechanics, from superposition to quantum tunnelling, and reveals why "the most powerful theory in the whole of science" remains incredibly mysterious. Plus, watch out for a fantastic explanation of the famous double slit experiment. Watch this video on the Ri Channel with additional learning materials: http://bit.ly/X826sE Friday Evening Discourses The tradition of Friday evening discourses at the Royal Institution was started by Michael Faraday in 1825. Since that time most major scientific figures have spoken in the famous Lecture Theatre at the heart of the Ri building at 21 Albemarle Street. Notable talks include Faraday announcing the existence of the technology of photography in 1839 and J.J. Thomson announcing the existence of the fundamental particle later called the electron in 1897.