I’ve heard the command “Reverse the Polarity!!!” on so many sci-fi movies and shows in the past. Was it just an early form of sci-fi techno-babble? Do they use it anymore?
Star Trek: “That Which Survives” 
In Transformers: The Movie, Kup (Lionel Stander) says:
Kup: Yep, like the shrikebats of Dramedan.
Hot Rod: How’d you defeat them?
Kup: I’m trying to remember…there were an awful lot of casualties that day. Oh, yeah! We inverted polarities!
Wasn’t there a line in the original Ghostbusters about something similar? I remember them saying, “don’t cross the streams,” but I thought there was something about reversing the polarity, too.
Here ya go (not quite polarity, but close):
Egon: I have a radical idea. The door swings both ways. We could reverse the particle flow through the gate.
Peter: How?
Egon: We’ll cross the streams.
Peter: Excuse me, Egon, you said crossing the streams was bad.
There was a “reverse the polarity” joke (actually “Reverse the Magnet!”) in the TV miniseries of Gulliver’s Travels, the one with Ted Danson. It was when the flying island of Laputa had to avoid being drawn in by a counter-magnet.
Reversed polarity can be a bad thing electrically, especially for electronics and some types of transformers. In movies, it’s done for effect and with a lot of poetic license.
Like “Take evasive action!” instead of “Run away! Run away!”
It’s used in Forbidden Planet (1956) I don’t have the context as I wasn’t taking notes. This may be the original usage but still makes no sense.
Why does Google-ing “reverse the polarity” turn up a load of financial pages rather than references to Voyager?
And start the reactor!!!
As a big fans of FP, which I’ve watched a gazillion times, I dispute this. I can’t recall them saying it. One reason I love FP is that the dialogue is surprisingly well thought-out and free of technobabble. When you can’t understand something, it’s still rooted in some assumed technology or science that’s self-consistent (like the whole stasis field thing at the start when they decelerate).
We had a hilarious thread about “Reversing the Polarity” on this Board about a year ago. Definitely worth looking up.
Quite. I was watching FP last night and I don’t think I hallucinated it. It jumped out at me because I’d read this thread otherwise I’d wouldn’t have noticed it. If I get time tonight I’ll see if I can find the context it’s used in.
That’s the first thing I thought of when I saw this thread title.
Who has time to look it up and provide a link? I’d do it myself, but I got a pie in the oven.
(small hijack)
In *The Right Stuff * Tom Wolfe talks about Chuck Yeager’s flight that first broke the sound barrier. There was something in it about one of the early theories on how to do this involved reversing something, perhaps the direction of engine thrust, at the moment you hit the sound barrier. Supposedly the pilot who first tried it died . Is there anyone out there who remembers this and what exactly the pilot was supposed to reverse? I can’t find my copy of the book.
(end hijack)
Here’s a segment of a transcript of Forbidden Planet which I’ve found. No character names, for some reason, but hopefully you’ll recognize the surrounding dialogue:
Not to reverse the polarity of this thread or anything, but in response to popular demand, here’s the previous polarity thread. 
From Forbidden Planet: Forbidden Planet Script - transcript from the screenplay and/or Leslie Nielsen movie (use control-F to locate the line.)
Captain: Attention. Captain to crew. Stand by to reverse polarity. Standard class “A” security will be maintained upon landing… and until further notice, all hands will wear sidearms. That is all.
Curse you, Frylock! I knew I shouldn’t have fiddled so long with the link! [sub]shakes fist[/sub]
From the book How I Did It, by Victor Frankenstein: (:D)
“…Until, from from this darkness a sudden light broke in upon me. A light so brilliant and wondrous, and yet so simple – change the poles from plus to minus and from minus to plus…”
And from Steve Martin, in his L.A. Story:
Harris: All I know is, on the day your plane was to leave, if I had the power, I would turn the winds around, I would roll in the fog, I would bring in storms, I would change the polarity of the earth so compasses couldn’t work, so your plane couldn’t take off.
Scrivener. the Frankenstein quote equals awesome.
-FrL-