This is a great talk by Fay Dowker about spacetime. However, since it is such a complicated topic, she had to start at the beginning and talk about atoms, entropy, the laws of thermodynamics, black holes, etc., in order to set the stage for her theory that spacetime is made up of discreet elements similar to atoms. This is called the Causal Set Theory. Here is a rather technical entry on Wikipedia, and here is another video recording of a lecture by Dowker at the Max Planck Institute for Gravitational Physics. Click on the “recorded talk” link to launch the video (not as visually friendly as the one posted below).  -- Dallas

Fay Dowker speaks at a Perimeter Institute Public Lecture on November 2, 2011. Black holes are hot! This discovery made by Stephen Hawking ties together gravity, spacetime, quantum matter, and thermal systems into the beautiful and exciting science of "Black Hole Thermodynamics". Its beauty lies in the powerful way it speaks of the unity of physics. The excitement arises because it tells us that there is something lacking in our understanding of spacetime and, at the same time, gives us a major clue as to what the missing ingredient should be. Theoretical physicists at Perimeter Institute and elsewhere are pioneering a proposal, known as Causal Set Theory, for the structure held by these most fundamental atoms of spacetime. In this talk, Professor Dowker describes  black hole thermodynamics and argue that it is telling us that spacetime itself is granular or "atomic" at very tiny scales.

More Perimeter Public Lectures can be found at: http://www.perimeterinstitute.ca/en/Outreach/Public_Lectures/View_P...