In order to build a practical time machine, AI must reach its maturity and it must be built in linear stages. The evolution of AI for the next 100 years comprising 3 recursive inventions that were invented by Mitchell Kwok: 1. Human Level Artificial Intelligence (aka True AI, Strong AI, and AGI) 2. Super AI (aka Super intelligent robots) 3. The Practical time machine. These 3 inventions are built on top of each other recursively and inherit all traits from its predecessor/s. You can’t build a practical time machine without first building super intelligent robots, and you can’t build a super intelligent robot without first building human level AI. All three inventions were patented by Mitchell Kwok between 2006-2008 (22 patent applications total). All 22 patents depict a full and comprehensive data structure to the practical time machine. This technology will be used to undo the 9/11 attacks.