Off-screen stage hands ensured the automatic doors on shows like Star Trek and The Next Generation always opened with impeccable timing and speed. And now Japanese robotics researchers have developed an intelligent sensor that could make the automatic doors at your local grocery store far less stupid.

The Riemann Hypothesis, which deals with the distribution of prime numbers, was first put forth by mathematician Bernhard Reimann in 1859. It has yet to be fully proven and remains one of the most important unproven theories in mathematics. It's so important that the Cray Mathematics Institute is even offering a $1…

There's something about secret doors that makes my spine tingle. The excitement! The mystery! But most secret doors are on the inside of a house—pull that book to reveal a hidden chamber! push that wall through!—this one, amazingly, is on the outside. It's so good you don't even see it.

If you're prone to losing your keys and finding yourself locked out of the house when you get home, you'll want to pay attention to this brilliant home mod by YouTuber oggfaba. Using hardware and lumber you can easily find at any home improvement megalopolis, they created a near invisible secret door that perfectly…

Doors are some seriously ancient tech but they have this problem where they can only keep people out if they're closed. This bizarre but clever take on the "revolving door" by a company called Barbecan, on the other hand, aims to get you inside, but simultaenously keep any ne'er-do-wells out. Specifically…

New York knew for a long time that a big storm could flood and collapse the subway system, which is exactly what happened with Sandy. Yet city officials did nothing about it. But now, after all the suffering, we'll finally be prepared.

Sure, the axe murderer presented in this door prop is about as lazy as they come, but you have to admit the overall attention to detail is pretty intense.

You get this odd looking piece, created by the Netherlands-based Dieter Volkers. It will ensure that nobody visiting your home/room takes you very seriously. [Dieter Volkers via Core77 via FastCo]

Marc DeVidts decided that his Miami residency needed to look more like the future, so what did he do? He added air-powered doors to his home. Thanks to his guide, you too can transform your kitchen into the bridge. [MAKE]

You probably don't spend much time thinking about door knobs, or how they could be improved. Maybe you should! This glass globe lets you catch a glimpse of what's going on in the room you're about to enter.

Those deep, curving shots from far outside the table would be impossible with this ping pong door, but that's OK. When I lose, which happens frequently, I can literally slam the door in my opponent's face. Imperfection. [Fubiz via Ffffound]

*Ring* *Ring* *Ring* *Ring* "What?!" "Oh sorry, I can't stop pushing your Spore doorbell." *Ring* "I'm calling the cops." *Ring*

If your household is statureally diverse, this 3-in-1 door from Slam Doors may be of interest. It features separate doors for kids and humiliatingly short adults.

It's an alarmingly simple concept that claims to be the world's first application: Netherlands-based company Natuurcafé La Port installed a power generator into a revolving door. Fantastic, but it took us this long?

Carbon fiber is pretty, and it's a cool technique to implement with car design... but what about doors? Who cares, you say? I agree, but it still didn't stop this door from becoming a reality.

The parking spaces at my apartment are so narrow that I have to suck in my gut and shimmy like a burglar on a ledge whenever I get out of my car. If I had this disappearing car door, however, that would be totally unnecessary. We don't want to spoil the video by describing it here, but suffice it to say that if this…

We can see how an electric door opener is useful for small children, the elderly, and the infirmed, but if you're using this because you can't manage to get off your ass for 30 seconds to open the door for the UPS guy, you should just go smack your mother right now for not raising the lazy out of you.