->''"DO NOT MESS WITH TIME."''
-->--'''Note From Harry's Future Self''', ''Fanfic/HarryPotterAndTheMethodsOfRationality''

In many time travel shows, the time machine is generally safe to operate, and the machinery itself is safe.

However, not all time machines are like that. Some could get downright dangerous to use, because trivial mistakes in any time of time machine operation could get time travelers dead. Worse, the world or more could get destroyed by the time machine itself. There can be many reasons on why the time machine itself is dangerous. What if the time machine overlaps matter on its arrival? What if what powers the time machine itself is dangerous, due to various reasons from radioactivity, instability, or just sheer amounts of power necessary? Or, what if some of the time machine's physics requirements are dangerous? Or what if the time traveler is likely to end up [[TimeAndRelativeDimensionsInSpace someplace unsafe]], like anywhere but the surface of the earth?

Now, not all time-related dangers are related with time machines. There are also many forms of time dangers, such as those caused by difference in time's flow. For example if there was a bubble of space where time is running 20 times faster, and you stick your hand in it, your hand will get 1/20 as much blood and therefore will start to die! Not to mention all the blood that was in your hand at first quickly accumulating in your wrist. You could lose your hand in a short time.

{{Temporal Paradox}} is a sub-trope to this. Compare TimeCrash, HyperSpaceIsAScaryPlace.
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!!Examples:
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[[folder: Anime and Manga ]]

* In ''{{Doraemon}}'', TimeTravel is achieved by going through a tunnel-like space on your TimeMachine. Shall one gets knocked out of the machine and into the tunnel, one will be stranded in time. The problem is, Doraemon's time machine is basically just some futuristic devices bolted to a ''tatami'', so the risk of being thrown overboard is always there. Dorami's is safe, because it's a flower-shaped capsule. Have we mentioned that some bad guys have their own time machine, [[PimpMyRide so you can have a chase in time while you chase in time?]]

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[[folder: Film ]]

* ''Film/{{Timecop}}'', as explained in the description, requires extremely high speed when they pass through the time travel field. There was one failure that just left two red spots on a heavy steel wall.
** That said, that's more NoOSHACompliance: After all, they ''could'' make the track twice as long to allow safe deceleration on failure...
*** Or make the track a centrifuge, so it'd be trivial to make a second pass at higher acceleration... like one illegal time traveler did in one of the books.
** In one episode of the short-lived ''Timecop'' TV series, the protagonist and his temporary partner (played by Creator/BruceCampbell) find a mothballed time travel lab in the past. They find an early version of the pod still using rocket boosters instead of the so-called "timecop propulsion". When Bruce Campbell asks what happened if the speed wasn't high enough, the protagonist pointed him towards the blackened wall at the end of the track.
* In ''Film/BackToTheFuture'', the [=DeLorean=] has to be traveling at 88 miles per hour. Which means that unless you know what's going to be in front of you in the time period you're heading to, you're going to crash.
** By the third movie, Doc seems to be acknowledging this. Marty's a little less sure, but both times Doc assures him that the obstacle he's seeing in the present won't be there in the destination time.
** Or that something that isn't there in the present ''will'' be there in the future, ([[spoiler:like the rest of the bridge.]])
* In ''Film/{{Primer}}'' excessive time travel causes strange physical problems in the protagonists: mysterious bleeding from their ears and deterioration of their handwriting. WordOfGod is that this is also a case of CloneDegeneration.
* In the 2002 film version of ''[[Film/TheTimeMachine2002 The Time Machine]]'', the titular device creates a spherical bubble to protect the occupant. Reach outside, that protection no longer applies. The main character hurts his hand when he instinctively grabs at an item he dropped. A Morlock wrestling with him on the machine ends up hanging outside the bubble, aging into dust. Logically, any attempt to reach outside the bubble should have violently scattered their atoms across dozens of years of history, but the RapidAging looked cooler, presumably.
* The directors cut of ''Film/TheButterflyEffect'' reveals that Evan suffers minor brain damage every time he majorly changes the past, resulting in severe migraines and nosebleeds as he gets the extra memories (often 20 years worth) burnt onto his existing ones. On the other hand, he's GenreSavvy enough to realise that repeated time travel might ultimately kill him, causing him to intentionally think through what he wants to change before each trip.

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[[folder: Literature ]]

* In one of Creator/LarryNiven's ''[[Literature/KnownSpace Gil "The ARM"]]'' stories, the time compressor invention was used to hide a murder. First, a witness was murdered in an impossible way - his head burnt to ash [[spoiler:by a flashlight from inside time compression sphere. The light come out hundreds of times stronger and literally burned the victim alive]]. Then another witness ''lost her arm'' poking the compressor, as she stuck her arm into an area where time moved faster - and deprived it of blood for several minutes. In the final arrest, the murderer was stuck inside the bubble and the cop was outside holding on to him by his legs. Unfortunately, the compression of time affected the killer in such a way that he died by thirst. Yes, the cop literally held the killer until he died of thirst. The effects of double time compression (One inside another) were discussed, and one of effects is that light speed inside the time compression sphere would be just a few feet per second. It means if a punch was thrown, the arm would get shorter!
* In ''The Time Ships'', the time traveling jeep was blown to pieces by intersection with a reverse growing tree while they were traveling backwards with expiring fuel. Lucky, the time travelers survived.
* One of MichaelMoorcock's ''Dancers at the End of Time'' short stories has a time traveller trying to warn her era about the future, only to find that ''time itself'' won't let her. The harder she tries the more her time machine overheats, but she refuses to give up and dies in agony.
* In the novel ''Literature/{{Timeline}}'', travel is accomplished by copying the information required to rebuild a perfect copy (at the atomic level) of the traveler and beaming this information into the past. Errors in copying are possible (in fact, inevitable if the machine isn't properly shielded) leading to CloneDegeneration.
** The beginning of the film version, the dead scientist's body scan revealed that part of his body appear to be slightly shifted from their normal place.
* In the short-short story "The Man from When" by Danny Plachta a time-traveller arrives from the future and states that his departure caused such an expenditure of energy that it completely wiped out the Earth of his time. He then reveals that [[spoiler: he has travelled back all of ''eighteen minutes''.]]
* In Kevin O'Donnell's story "Gift of Prometheus" a malfunctioning time bracelet freezes its wearer outside of time and space with a bullet in his gut, [[AndIMustScream unable to do anything but suffer]] and wonder if it will last forever.
* ''Literature/TheDivingUniverse'': Stealth tech creates bubbles of altered time, which are usually fatal to anyone unfortunate enough to stumble into them.
* In the [[MagicTheGathering Magic: the Gathering]] novel ''Time Streams'', a lab explosion results in areas where the passage of time is slowed down or sped up; blindly stumbling into these areas from the outside is usually a cheap ticket to a messy death. Several students are caught in an area of extreme slow time, where decades later they're still living out the initial seconds after the explosion. Passage into and out of these desynchronized areas is eventually developed, allowing research to skip ahead at a prodigious pace.
* In ''Strange Attractors'' by WilliamSleator, the creation of a CrapsackWorld AlternateUniverse is almost the only outcome that could come of sending anything (much less a person) into the past.
* In the ''Literature/HostileTakeoverSwann'' series, going the wrong way through a wormhole takes you back in time. The entrances of wormholes are heavily guarded, though, and anyone coming through is shot. Also, because of the butterfly effect, you're in a new timeline, which will never become the exact future you came from.

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[[folder: Live Action TV ]]

* In a ''Series/StarTrekTheNextGeneration'' episode, "Timescape", Picard is injured when he sticks his hand across the edge of a "time bubble", which causes his fingernails to age faster than his arm. Later, he experiences symptoms of "temporal narcosis" due to a malfunction of the equipment protecting him from being frozen in time.
** Ironically, its mentioned that taking the "armband" off would merely freeze someone in that timeframe with no ill-effects from the rapid transition from one to the other. Time is funny like that.
*** [[GeniusBonus Or because that particular time bubble was an extreme slowdown while the one encountered earlier that harmed Picard's hand was an extreme speed up. It would make sense that taking off the armband would move you into that time reference.]] Meaning if you took off your arm band in an extreme speed up it would age you into dust, while taking it off inside a slow down would well... [[CaptainObvious slow you down ]]
** A ''Series/StarTrekVoyager'' episode "Shattered" has Chakotay end up in a temporal anomaly that results in various parts of his body having different ages. The Doctor manages to stabilize him. Apparently, they covered this at the Starfleet Medical Academy.
** Another episode "Blink of an Eye" has an astronaut from a planet were time operates in a faster rate than the regular universe, ends up dying during the transition to the timeframe on Voyager, while the other one barely survives.
* In one ''OuterLimits'' episode, the result of RippleEffectProofMemory is that an entirely new lifetime's worth of memories gets added onto the existing one, which could result in brain damage.
** Another episode had a time traveller end up a few days in the future to see his wife dying from a gunshot wound. He goes back and tries to prevent it. However, the side effect of the trip is physical and mental degradation. By the end, his wife has had enough and decides to leave him. In a deranged state, he ends up shooting her. Seems to be a case of YouAlreadyChangedThePast, doesn't it? Then the episode does a 180 on this idea and has the guy go back to the night he first met his wife and shoot his younger self, himself turning to dust. Of course, the worst part is that she was planning on killing herself that day.
* ''Series/SevenDays''. There are so many things wrong with the Sphere. First of all, while it's [[ExactlyWhatItSaysOnTheTin very accurate]] [[TimeAndRelativeDimensionsInSpace in time travel, landing it]] ''[[TimeAndRelativeDimensionsInSpace where]]'' [[TimeAndRelativeDimensionsInSpace you want to be]] requires precise piloting. Second, [[OurTimeTravelIsDifferent Our Time Travel Is]] '''''[[AgonyBeam really]]''' [[AgonyBeam painful]]''. Third, well, go to the page and check out the list of {{Phlebotinum Breakdown}}s the machine suffered. That's probably not even the full list!
* ''{{Sanctuary}}'': A time bubble allows people to enter, but violently destroys anything attempting to leave. Time inside the bubble runs six years to each day outside, resulting in three-year periods of no sunlight. Naturally, this is not good for a self-contained ecosystem. Furthermore, if the bubble had expanded too far, the time differential between the different parts of the Earth would have destroyed the planet. [[spoiler:Will and Magnus manage to reverse it, but at the cost of [[RetGone ret-goning]] everyone born inside the bubble.]]
* ''Series/SapphireAndSteel'': Time is outside the (metaphorical) safe corridor in which human life and history exist, and it is constantly trying to exploit weak spots in the corridor walls and break in. This, when it happens, is not a good thing. Time is the ''enemy''.

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[[folder: Newspaper Comics ]]

* In [[http://www.gocomics.com/calvinandhobbes/1987/09/02 this]] ''CalvinAndHobbes'', the dangers of using a [[BambooTechnology cardboard time machine]] are discussed.
--> '''Hobbes:''' Why do we have to wear goggles?
--> '''Calvin:''' Geez, do you think traveling years into the future [[CasualTimeTravel is like driving down the street?!]] We've got to contend with [[SwirlyEnergyThingy vortexes]] and [[FasterThanLightTravel light speeds]]! Anything could go wrong! Of course we have to wear goggles!
--> '''Hobbes:''' Gosh, I think my goggles are in the bedroom. If I'm not back in a couple minutes, you can go without me.

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[[folder: Video Games ]]

* ''{{Achron}}'': You can Chronoport your units back in time. It's like teleporting, but for time instead of space. You just need to make sure the arrival point isn't [[TeleFrag occupied by anything]]. Like, say, your unit's [[TemporalParadox past self]].
* ''{{Final Fantasy XIII-2}}'': Resolving paradoxes and fixing the timeline forces the seeress ([[WaifProphet Yeul]]) to see all of the changes caused, up and down the timeline. This happens to shorten her lifespan a little every time, the symptoms progressing from collapsing, to [[FaintingSeer falling unconscious]] to (ultimately) [[HeroicRROD dying]]. [[spoiler:Serah happens to have the same powers. It makes for a [[TheHeroDies depressing]] [[DownerEnding ending]].]]

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[[folder: Webcomics ]]

* [[http://mindmistress.comicgenesis.com/gift1.htm This]] MindMistress story explores some dangers of time flow differences. Among other dangers, it's very unwise to hit anything hard while sped up. [[spoiler: Being trapped in high speed was not too healthy for someone, as she died by age in short real time.]]
* Webcomic/RealLifeComics [[http://www.reallifecomics.com/archive/110616.html This strip]] touches this subject with a discussion after a time bubble was used to rapidly age mead 6 months.

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[[folder: Web Original ]]

* Website/{{Cracked}}.com has a [[http://www.cracked.com/article_18564_6-time-travel-realities-doc-brown-didnt-warn-us-about.html list of reasons why time travel sucks]].

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[[folder: Western Animation ]]

* In the ''WesternAnimation/BatmanTheAnimatedSeries'' episode "Time Out of Joint", Clock King uses a time-altering device to trap Batman and Robin in a "bubble" of slowed time, where [[YearOutsideHourInside seconds for them pass as hours on the outside]]. Batman points out that objects "outside" the bubble are moving relatively at tens of thousands of miles an hour while they are comparatively "standing still". Meaning there will be an enormous (think asteroid impact or nuclear weapon) explosion if anything collides with them in their "frozen" state. Fortunately Batman defuses the trap before it can happen.
** FridgeLogic suggests that everybody outside the bubble just saw the Batmobile parked in the middle of the highway for a full day (or however long they were trapped), with the dynamic duo sitting nearly motionless inside. It's a good thing nobody tried to knock on the window to see if they were ok.
* The final episode of ''{{Futurama}}'' deals with the Professor inventing a literal ResetButton that rewinds time by ten seconds, affecting anyone who isn't in the button's radius or in the Professor's special shelter. When someone or something leaves the shelter and the button is used immediately afterwards, the something or someone is disintegrated. This happens to both a ten dollar bill the Professor scams Zoidberg out of using the button, and [[spoiler:the Professor himself, though he manages to undisintegrate himself later on]]. And when Fry accidentally breaks the button by stepping in it, [[spoiler:it freezes time for everyone and everything except him and Leela, who were both in the button's radius at the time]].

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