If the hover board isn’t made in three years, a scientist from the future could go back in time and create it so it’s made on time.  However, if he comes face-to-face with himself, he could either pass out… OR… the encounter could create a time paradox, the results of which could cause a chain reaction that would unravel the very fabric of the space time continuum, and destroy the entire universe!  Lu-haaate!

If the hover board isn’t made in three years, a scientist from the future could go back in time and create it so it’s made on time.  However, if he comes face-to-face with himself, he could either pass out… OR… the encounter could create a time paradox, the results of which could cause a chain reaction that would unravel the very fabric of the space time continuum, and destroy the entire universe!  Lu-haaate!