''The Philadelphia Experiment'' is a ScienceFiction film published in 1984 about TimeTravel.

Two sailors from 1943, David Herdeg and Jim Parker, become FishOutOfTemporalWater when the US Navy destroyer they are stationed on vanishes as an unforeseen side-effect of an experiment in creating an electromagnetic InvisibilityCloak, and they find themselves in 1984. While they deal with the culture shock, Parker gets sick and vanishes, apparently sucked back in time. Herdeg, searching for an explanation for what happened to him, winds up at a military installation where it is revealed that a second cloaking experiment is underway, this time involving an entire city. It, too, vanished, and now there's a huge vortex in the sky that is sucking everything into it and growing larger.

It turns out that the interaction of the two experiments, one in 1943, the other in 1984, has created a [[TimeCrash time warp]] that captured both the destroyer and the city and threatens TheEndOfTheWorldAsWeKnowIt. Herdeg is given an experimental suit to protect himself from the effects of the vortex, and allows himself to be sucked back in in an attempt to shut down the destroyer's cloaking field.

The movie is InspiredBy, and takes its name from, a supposed ''real'' [[http://en.wikipedia.org/wiki/Philadelphia_Experiment invisibility experiment conducted during WWII]] which resulted in the same "side effects" as depicted in the movie. Today it's regarded as being little more than the stuff of overactive, discredited conspiracy theories.

A sequel, ''The Philadephia Experiment II'', was released in 1993. Herdeg wakes up one morning to discover that Germany has retroactively conquered the United States, apparently having won WorldWarTwo using a mysterious super-bomber. It turns out that yet another teleportation experiment resulted in the transportation of a nuclear-armed F-117 Nighthawk stealth fighter to 1943, and he must return to the past to stop it from being used by the Nazis. It features none of the original cast.
!!Tropes present in ''The Philadelphia Experiment'':

* AllIsWellThatEndsWell: Despite the fact that Herdeg is indirectly responsible for the burning death of a car full of his subordinates, and the injury of some in the one he was riding in, he's more than happy to be the one driving Herdeg out (and engaging him in idle chit chat "So, what did you think of 1984?") so he can get back to 1943.
* BasedOnAGreatBigLie: Aside from a complete lack of any evidence supporting the experiment, the USS Eldridge was in the Carribean on a shakedown cruise during the dates specified, and four of the men mentioned by name to have died actually survived the war, one of whom eventually commanded his own ship.
* BodyHorror: After the ship returns from its trip many of the sailors are severely burned, but several are even seen "phased" halfway through a metal walkway... still living.
* CaliforniaDoubling: "Philadelphia" is actually Charleston, South Carolina. The "docked" ships you see are at [[http://en.wikipedia.org/wiki/Patriots_Point Patriot's Point]], and you can even see the first nuclear powered mercantile vessel, the [[http://en.wikipedia.org/wiki/NS_Savannah NS Savannah]] there in the film (it was moved from there in 1994), a huge anachronism.
* ConflictBall: [[JustEatGilligan All Herdeg had to do was go with the military]]. He is never given any reason ''not'' to trust the military -- when the group of soldiers comes down the hall at the hospital, he just runs for no reason. Of course, judging by his character through the movie, he's not the brightest bulb. It gets worse when Herdeg meets the man who he takes into the base at gunpoint who out-and-out tells Herdeg "You'll never get into the base -- it's secure!" despite the fact that that very base was the one looking for Herdeg. The conflict is all quite contrived, but TropesAreTools.
** They do get chased by a helicopter which opens fire on them without warning, but that's ConflictBall, too.
* CoversAlwaysLie: The cover (seen here) is misleading. The dark thing with the headlights in the center had nothing to do with the actual experiment, Herdog is actually riding out in it at the end of the movie to fix everything.
* DevelopingDoomedCharacters: There's a long segment at the beginning setting up the fact that Parker is in love (or married already), which takes place at a dance.
* DidNotGetTheGirl: Subverted. Herdeg is forced to leave his LoveInterest, Allison, behind when he enters the time vortex. It's strongly hinted that he'd eventually have been sucked back just like Parker anyway. [[spoiler:But then he jumps off the destroyer before the time vortex collapses, reappearing in 1984 after a DisneyDeath.]]
* DisneyDeath: Herdeg jumps off of the ''Eldridge'' into the vortex just before it collapses. The destroyer reappears in 1943, the town reappears in 1984, and everyone's happy (except for the horribly maimed sailors, one imagines), but where's the hero? [[spoiler:Cut to Allison walking through the town... and there's Herdeg.]]
* DrivingStick: [[InvertedTrope Inverted]] Upon commandeering Allison's car, Herdeg is so dumbfounded by the lack of a clutch pedal that he has to make Allison drive.
* FishOutOfTemporalWater: Actually some scenes of this were deleted. The most subtle bit was Parker's reaction to the bill for two breakfasts and coffee -- which probably cost several times the dollar amount it would have in 1943, but we just see his reaction to the check, not the price.
* {{Foreshadowing}}: Parker's wife in 1984 tells Herdeg that, "You never came back."
* TheFutureIsShocking: The culture shock of Parker and Herdeg arriving in 1984 is played up until they start getting chased by the military.
* GoneHorriblyWrong: The cloaking experiment is intended to hide a ship from radar, not make it vanish entirely.
* TheGuardsMustBeCrazy: One soldier manages to get onto the elevator with Herdeg. There are lots of innocent bystanders there. The guard waits until ''after'' a stop when someone is let onto the elevator -- the perfect opportunity to get Herdeg away from said bystanders -- and waits until the elevator is even ''more full and the door shut'' before attempting to restrain Herdeg.
* InvisibilityCloak: For a navy destroyer and an entire midwestern town. It's actually intended just to hide them from radar, but clearly doesn't work exactly as intended.
* JustEatGilligan: As under ConflictBall above, all Herdeg and Parker had to do was check in with the military and explain their story. The scientists were indeed looking for them and didn't mean them any harm.
* LemmingCops: Pursuing cars ''on foot through snow''. Chasing a car through a barn, flipping one car and [[MadeOfExplodium exploding]] the other after it rolls.
* MassTeleportation: A U.S. Navy destroyer and an entire town get sucked into the time vortex.
* OurTimeTravelIsDifferent: The wormhole version.
* ProductPlacement:
** Löwenbräu beer.
** Coke, several times. The most obvious is the man holding the can label-out as they watch the results of the missile-probe.
** Herdeg watches a commercial for the [[http://en.wikipedia.org/wiki/Rainbow_100 Rainbow 100]], which really was a computer for sale in the 1980's.
* TheSlowPath: Poor Parker has to live out 41 years of ridicule while his buddy Herzeg gets to gallivant around in 1984. No wonder he's bitter.
* TimeTravelForFunAndProfit: Parker owns a ranch, but he doesn't seem to be any wealthier than he could have been otherwise. [[spoiler: Herdeg, however, makes a joke at the end about the military probably owing him 40 years of back pay.]]
* TemporalParadox: Of the ontological sort -- if the time vortex is stopped back in 1943, then how does it start in 1984 and cause the events of the movie? This is, [[MST3KMantra perhaps mercifully]], left unanswered.
* TimeCrash: The time vortex created by the interaction of the two experiments will cause a horrible calamity if not stopped, as the 1984 end seems poised to suck up the entire planet. There's no corresponding vortex in 1943, however.
* TimeTravel: Accidental time travel caused by two experiments in electromagnetic cloaking 41 years apart.
* VeryLooselyBasedOnATrueStory: There was a project involving degaussing naval ships to allow them to pass through a field of magnetic sea mines. One sailor was electrocuted, but otherwise it was a success. That's about the closest the film gets to reality.
* WalkingTechbane: Of the accidental type; absorbing the electrical shock from the destroyer's generator causes Parker (and later Herdeg) to occasionally short out nearby electronics and attract thunderstorms.
* WhatHappenedToTheMouse: Blink and you'll miss it -- After Herdeg turns off the machine in 1943 and as he walks over to talk to Jimmy on the ship, he puts his 1984 gloves in his 1984 helmet and tosses it off to the side. He never retrieves them, leaving them in 1943. The movie's almost over, and there's no time to bring this up. He returns to 1984 without them.
* WhatYearIsThis: Parker and Herdeg figure out that they're in the future from copious clues, but have to ask for the precise date.
* YouHaveToBelieveMe: Parker's "insane" story of traveling in time got him put in a mental institution after he was sucked back. When Herdeg looks him up in 1984, he's a bitter old man.

!!Tropes present in ''The Philadelphia Experiment II'':
* ALittleSomethingWeCallRockAndRoll: Rock's absence in the alternate Nazi-run America is indirectly noted. The main bad guy is introduced as he tries to decide what background music to use for a propaganda film celebrating 50 years of totalitarian rule. After listening to Mahler, Wagner, Strauss, and Handl, he decides that "highbrow Eurotrash" won't cut it. Later on, he settles on country swing, but it still doesn't sound quite right.
* AlternateHistory: A scientific experiment sends a stealth fighter carrying nuclear bombs back in time to 1943. The Nazis capture the jet and use it to bomb Washington D.C. and win WorldWarII.
* ForWantOfANail: A rather ''big'' nail, but still.
%%* TheFutureIsShocking
* GivingRadioToTheRomans: Albeit by accident -- a stealth aircraft armed with nuclear bombs is transported back in time to Nazi Germany, where it's used to attack several cities in the eastern United States.
* GodwinsLawOfTimeTravel: The point of the film.
* GoneHorriblyWrong: You'd think that scientists in this world would have figured out by now not to try to teleport things or make them invisible.
* RippleEffectProofMemory: Somehow the altered modern timeline knows about what went wrong in the unaltered one.
* SetRightWhatOnceWentWrong: A variation in that Herdeg has to fix the past to stop the future from screwing with the past.
* StableTimeLoop: Inverted; see below.
* StupidJetpackHitler: Thanks to TimeTravel.
* TemporalParadox: In this case, [[SetRightWhatOnceWentWrong setting right what once went wrong]] ''destabilizes'' the StableTimeLoop and erases the entire incident from ever having happened.
%%If you are adding tropes for the first movie, there are TWO films listed on this page. Add tropes for the first movie ABOVE where it says "Tropes present in ''The Philadelphia Experiment II'':" %%