Transcript: http://www.davidcolarusso.com/blog/?p=33#more-33 This video is an adaptation of an earlier piece of mine--Perspective on quantum mechanical tunneling. That film, however, was designed for a unique audience, and I felt its overall length was limiting its appeal here. So I've repackaged it as one of my Explainer episodes. I Hope you enjoy. People have been asking for the math. So here it is. The Sun's core temp is ~13.6 MK. For hydrogen nuclei the Coulomb barrier is roughly 0.1 MeV. This corresponds to a temperature in excess of 1 GK! Luckily, tunneling and the distribution of speeds among nuclei lower the actual temperature required. So without tunneling even the Sun's core isn't hot enough for fusion. To see most of this worked through, check out this link: http://burro.cwru.edu/Academics/Astr221/StarPhys/coulomb.html for a less mathematical explanation, try: http://en.wikipedia.org/wiki/Nuclear_fusion#Requirements The Tabletop Explainer is an intermittent educational vlog presenting answers to viewer questions, brief science lessons, and ideas for teachers and students. It is a feature of my blog "Tilts at Windmils" which can be found at http://www.davidcolarusso.com/blog/