Seven years after Elon Musk first challenged innovators to develop a functioning hyperloop system, Richard Branson-backed Virgin Hyperloop and Hyperloop TT are in a race to bring the high-speed transportation technology into the real world. Photo illustration: George Downs More from the Wall Street Journal: Visit WSJ.com: http://www.wsj.com Visit the WSJ Video Center: https://wsj.com/video On Facebook: https://www.facebook.com/pg/wsj/videos/ On Twitter: https://twitter.com/WSJ On Snapchat: https://on.wsj.com/2ratjSM #WSJ #Hyperloop #ElonMusk