Star Trek‘s technological legacy is vast. Kids watching back in the ’60s grew up and invented the cool things they saw in the show. Tablets, video calls, and flip phones are all real-life gadgets inspired by Star Trek tech. Food replicators and medical tricorders are not far off. But did you know that automatic sliding doors belong on that list as well?

Those of us who were not alive yet when the original series came out may have no idea that this technology blew people away at the time. Famed astrophysicist Neil deGrasse Tyson has even said it was the least realistic part of the show to him. When he watched as a kid, space travel and warp drive were believable enough. However, doors that knew when you wanted them to open seemed truly too good to be true. Let’s explore a bit about the history of those automatic doors, both in Star Trek and in real life.

Captain Kirk and Spock walk into a turbolift on Star Trek The Original Series
Paramount Pictures

When Were Automatic Doors Invented?

An engineer in ancient Greece actually invented the earliest known version of automatic doors nearly 2,000 years ago. It involved fire, pulleys, and a priest. The mechanism was designed to give the illusion that a divine power opened the temple doors. The next automatic door wasn’t around until 1931 but only existed in one restaurant in Connecticut. It swung open and closed to allow waiters back and forth to the kitchen.

Engineers invented the first automatic sliding doors in 1954 and they became commercially available in 1960. But they used a mat on the floor to trigger the doors, which is definitely not the case in Star Trek. They didn’t really catch on until the addition of motion sensor technology in the 1970s, after Star Trek‘s run. In the ’80s and ’90s, infrared technology advanced. Most automatic doors now use that to determine when to open and close.

Paramount Pictures

Their use in popular places like gas stations, grocery stores, and airports increases accessibility. It also removes the need to touch door handles and other surfaces. But because the infrared devices monitor a large space around the doors, they still open even if you’re just walking by. And that’s something that makes the doors in Star Trek smarter still than what we have today.

How Do Doors Work on Star Trek?

There’s some continuity questions about the doors in Star Trek. Some come with a button, others respond to voice commands, and then there’s those that magically know when to open and close. Private quarters have a chime and some sort of voice recognition. Other doors only open when characters actually intend to go through them, something that sets them apart from modern automatic doors. There are many scenes of people loitering near doorways that don’t open. With real-life automatic doors, people walking by, animals, or even a strong breeze can trigger them.

Paramount Pictures

Since the beginning, a distinctive sound has accompanied the doors. It has changed over time but is likely still dubbed rather than the actual on-set audio. The whooshing certainly implies some sort of pneumatic air-powered door. Rumor has it that the original foley is actually the sound of someone pulling paper from an envelope. We do see a few manual doors, like those in Wesley Crusher’s dorm at Starfleet Academy, though characters in universe consider them antiquated relics.

Does Star Trek Use Automatic Doors on Set?

In the original series, a stagehand operated the doors behind the scenes. Wires attached to the doors ran through a series of pulleys. The assistant director triggered a light, the person in charge of the door pulled on the mechanism, and the doors would open. It seems that the same setup was used on The Next Generation, which likely means it was on Deep Space Nine, Voyager, and movies during that time as well. Enjoy the blooper compilation below where mis-timed doors on both shows trigger late, early, or not at all. Just like in our reality, perhaps the on-set doors should come with caution signs.

Much of the publicly available information about the sets of the more recent shows and movies are actually from blooper reels. Chris Pine grappled with a door during at least one of the Star Trek movies. Based on a set tour of Strange New Worlds available to watch on Paramount+, it appears the doors slide open at the push of a button. Since they open automatically in universe, most likely an on-set crew member triggers the door out of frame when Pike and his Enterprise crew need to pass through.

Automatic sliding doors are present from the pilot episode (both of them) of the original series to the finale of Strange New World’s inaugural season (the most recent live-action episode to air). Of all the many questions we have about Star Trek, the most pressing is: when did automatic doors come to the set?

Paramount Pictures

Gene Rodenberry’s Star Trek legacy is many-fold and ever-lasting. Important people were molded by their love of the show. The diverse casting in every series advances civil rights around the world. And then there’s the technology. That something as ubiquitous as automatic sliding doors are now was once a science fiction dream is just one more testament to Star Trek‘s lasting legacy.

Melissa is Nerdist’s science & technology staff writer. Her text messages arrive to the sound of TNG’s door chime. Melissa also moderates “science of” panels at conventions and co-hosts Star Warsologies, a podcast about science and Star Wars. Follow her on Twitter @melissatruth.