This question might involve too much current for an electronic engineering board, but it involves electricity, so I'll ask it anyway.
YouTube videos of the railgun https://www.youtube.com/watch?v=ZL4kbBIf39s show a curious phenomenon; billowing clouds of what appear to be flame emerging from the barrel. Those are understandable from conventional cannon, because there is combustion continuing after the projectile leaves the tube, but railguns don't use combustion.
What's going on? They're far too fractal to be supersonic shock waves. Are they plasma, glowing atmosphric gases that have been heated by compression in front of the projectile, or something else?
Drones are, in essence, flying autonomous vehicles. Pros and cons surrounding drones today might well foreshadow the debate over the development of self-driving cars. In the context of a strongly regulated aviation industry, "self-flying" drones pose a fresh challenge. How safe is it to fly drones in different environments? Should drones be required for visual line of sight – as are piloted airplanes? Join EE Times' Junko Yoshida as she moderates a panel of drone experts.