By now, you know Brian Beckman given how many times he's been featured on Channel 9 and, well, just how amazing he is. Brian is an astrophysicist and software architect currently working on a technology we can't talk about...yet...Stay tuned for that. Dr. Beckman is the perfect choice for a new lecture in the C9 Lectures series. This is a single lecture, but there will be more interesting conversations to come on this deep and beautiful topic (in some sense, this is all about symmetry).In the Rx interview with Brian and Erik Meijer , a short discussion on covariance and contravariance took place as a tangential topic (which often happens in real conversations - and we love that!). The concepts of co/contravariance can confuse and confound. Also, they are not just related to programming.Here, Dr. Beckman teaches us about covariance and contravariance in physics. Are these universal properties? Do they apply to the mathematics of physics (from quantum mechanics to black holes) in the same basic way they do for general purpose programming with objects and lists, for example?Tune in. This is a deep dive lecture and quite mathematical. Don't be scared. As usual, Brian explains complex things in a readily understandable fashion for mere mortals. If you have no experience with math and physics, this may be a bit challenging, but certainly not entirely over your head.Enjoy.: You should download the supporting document and slides (you should download the MathType fonts here ). This will help you learn faster!