Carl Sagan was awesome, he was an American scientist, his interests were pretty broad, he was an astronomer, astrophysicist, cosmologist and astrobiologist, and he was also passionate about teaching science to the general public; he wrote a number of science books and had an award winning TV series called Cosmos: A Personal Voyage. Sadly he died in 1996 aged only 62.
In this video he’s talking about the Drake Equation, the equation used to estimate the number of advanced civilizations in our Galaxy. It’s an awesome concept, and Carl explains it beautifully.
We don’t know the values of most of the variables in the equation yet, particularly the ones towards the end, as Carl demonstrates by calculating an answer between 10 and millions of advanced civilizations, but the Drake Equation is a great way to help us organise our thinking about astrobiology and the search for extraterrestrial life (SETI).
It’s also fun to work out your own answer to the equation based on what you belief the value for each variable should be.
If you want to read more about the Drake Equation I’ve written a short post here.