Marty McFly is probably riding his hoverboard into the further future because it’s 2015, and we still don’t have them yet. There’s a reason we don’t have hoverboards, jetpacks, or flying cars just yet: physics. It’s tough to get things off the ground without a great amount of power and propulsion pushing downward. Lexus’s test hoverboard uses nitrogen-cooled superconducting magnets to hover above the ground, but it can only do so above another magnetized surface. Jetpacks are tough, too; you have to push enough energy toward the ground without blowing your feet off. And flying cars have no regulation yet, mainly because the government hasn’t had to deal with anything that’s road-legal and legal to fly as well.