Science & Technology Q&A for Kids (and others) [October 1, 2021]

Stephen Wolfram answers general questions from his viewers about science and technology as part of an unscripted livestream series, also available on YouTube here: https://wolfr.am/youtube-sw-qa

Questions include: Why do flies fly around seemingly constantly with no apparent goal whatsoever? - Why don't we make houses out of some kind of amber and then carve them? - How do traffic light systems work? - Does Stephen prepare any of the answers? they are all so clear and thought out - Hello, how are the magnetic north and geographical north related? - 1 How come oil is deposited in Arctic regions? -  Could you please explain what Eigenvalues/vectors and what you can do with them. Thanks.