Why did the US military dig a tunnel in the Alaskan tundra? What is the tunnel used for now? Visit https://www.kiwico.com/physicsgirl30 to get 30% off your first month of any subscription! Support Physics Girl videos → https://www.patreon.com/physicsgirl Special thank you to our X-Ray tier patrons: Carlos Patricio, David Cichowski, Eddie Sabbah, Fabrice Eap, Gil Chesterton, Isabel Herstek, Margaux Lopez, Matt Kaminski, Michael Schneider, Patrick Olson, Vikram Bhat, Vincent Argiro, wc993219 Music provided by APM https://www.apmmusic.com/ If you liked this video check out these: A picture of the beginning of the universe → null. Why is the Universe Flat? ft. Prof Alan Guth → null. http://physicsgirl.org/ http://twitter.com/thephysicsgirl http://facebook.com/thephysicsgirl http://instagram.com/thephysicsgirl Creator/Host: Dianna Cowern Editor: Levi Butner Producer: Kyle Kitzmiller