Governor Eric Greitens made a big futuristic splash yesterday when his office announced that a hypothetical Hyperloop would be included in the state of Missouri's bid for Amazon's second headquarters.The proposal suggests that a big tube connecting St. Louis to Kansas City will surely convince Jeff Bezos and Co. that the Show Me State is the place for them. The tube would use magnets, somehow, to blast passengers at top speed from one side of the state to the other in about 30 minutes time. By taking this approach, Greitens is able to offer Amazon two cities for the price of one (and, notably, gets to walk the line between the desires of his state's two largest metropolitan areas without committing to either of them).…