History Main / WhenDimensionsCollide

# A world with overly simple rules and internal logic entered by somebody from an Earth-like world. These works are more prone to humor as the native inhabitants fail to understand or loudly disbelieve things which would be obvious to normal humans.
# A world which has an alien set of physical laws (or somebody from it), that then interacts with an earth-like world. Type II worlds are almost always in the horror genre. Visitors from these worlds are often either {{The Fair Folk}} or {{Eldritch Abomination}}s.

* ''WebComic/UnicornJelly'': The dimension of Tryslmaistan periodically intersects with other dimensions, including that of Earth, leaving those residing in those portions of the other worlds stranded in Tryslmaistan. While the physics (and inhabitants) of Tryslmaistan are somewhat hostile to terrestrial life, it is similar enough that human castaways are able to form a civilization on the Myrmil Worldplate [[spoiler: before catastrophe struck and they needed to move on to other Worldplates]].

* ''WebComic/UnicornJelly'': The dimension of Tryslmaistan periodically intersects with other dimensions, including that of Earth, leaving those residing in those portions of the other worlds stranded in Tryslmaistan. While the physics (and inhabitants) of Tryslmaistan are somewhat hostile to terrestrial life, it is similar enough that human castaways are able to get form a civilization on the Myrmil Worldplate [[spoiler: before catastrophe struck and they needed to move on to other Worldplates]].

* ''Series/TheWitcherBloodOrigins'' concludes with a front-row seat to the Conjunction of the Spheres. Orange fire burns at the edges of interdimensional portals in the sky, revealing multiple planets from a satellite view. These portals merge and give the appearance of WhenThePlanetsAlign, concluding with some kind of ''flash'' that leaves everyone in all worlds unconscious as volumes are swapped with one another. The first survivors are beached on the shores[[note]]implying that the differences in heights at swap meant the highest survival rate was with those who were in seaworthy ships at the time[[/note]] who start asking each other questions only to discover they speak wildly different languages. The details are fudged from the original novels, [[spoiler:as elves had already conquered the world of the dwarves 1,500 years ago, and some of the humans transported were still in the Age of Sail rather than post-cyberpunk]].

* ''Film/Barbie2023'': This is part of the nature of Barbieland as a dimension formed of [[Main/Tulpa thoughts and ideas]], as real world concepts inherently shape it. However, properties of the real world such as depression, cellulite, and other aspects of genuine humanness that are not usually present in Barbies begin bleeding over into Barbieland [[spoiler: due to America Ferrera's character's imagination affecting Barbies]].

* ''Film/Barbie2023'': This is part of the nature of Barbieland as a dimension formed of [[Tulpa thoughts and ideas]], as real world concepts inherently shape it. However, properties of the real world such as depression, cellulite, and other aspects of genuine humanness that are not usually present in Barbies begin bleeding over into Barbieland [[spoiler: due to America Ferrera's character's imagination affecting Barbies]].

* ''Literature/TheGodsThemselves'' is a story based around a new form of energy that arises when people discover how to exchange matter between parallel universes. The protagonist slowly realizes that as they exchange matter between worlds some of the cosmological constants also change very slightly, but with potentially apocalyptic consequences.

* ''Series/BuffyTheVampireSlayer'': In Season Five, the exiled hellgod Glory is trying to re-enter her dimension, but the effort would cause all dimensions to collide (thus destroying the multiverse). Small glimpses of this process can be seen in "[[Recap/BuffyTheVampireSlayerS5E22TheGift The Gift]]", when places on Earth get changed and twisted and creatures from other dimensions including Xenomorph-like demons and a dragon enter our realm.

* ''VideoGame/CorpseParty'' takes this trope to [[UpToEleven extreme lengths]]. The protagonists are trapped in what are mentioned "closed spaces layered over closed spaces". In each chapter, the main characters you play as are all in the same school, but a different rendition of it, with events [[TimeyWimeyBall taking place before or after each other]] that seep into the others' dimensions. Best example is [[spoiler: how Ayumi leaves candles for others that act as a SavePoint after she and Yoshiki look for Seiko when she screams... yet when you play as Naomi and Seiko in Chapter 1, ''the candles were already there'']].

* ''Series/StarTrekTheNextGeneration'': In one episode, aliens from another universe with very different physical laws invade the main universe and start running experiments on the ''Enterprise'' crew. They manage to create a temporary environment where the laws of physics allow inhabitants from both universes to co-exist, but normal parameters within that universe do pretty crazy things to people's body chemistry.

*** In ''The Shackled Hut'', Queen Elvanna of Irrisen captures Literature/BabaYaga's dancing hut and chains it on display in her capital's market square. The hut defends itself by forcing a breach to the First World, causing an impassably thick forest of conifers, which grow back as fast as they're cut down, to grow overnight in the square and spread for several blocks before being stopped. The result is a patch of TheLostWoods sitting incongruously in the middle of a large city's merchant district, filled with a mix of stranded locals and of First World beasts and natives that found themselves dragged into the material world alongside the forest.

* In ''Alternate Routes'' by Creator/TimPowers, a secret government project is studying an otherworld where the laws of reality are much looser. Over the course of the novel, it increasingly leaks into our world, and it turns out the villain is trying to merge the two worlds entirely, which would result in our physical laws being dissolved in the otherworld's chaos.

* One hypothesis for the [[https://en.wikipedia.org/wiki/CMB_cold_spot CMB Cold Spot]], also known as the Eridanus Supervoid -- a zone of the universe where the cosmic microwave background is much colder than other areas and matter is relatively scarce, is that it's a scar left behind when our universe brushed up with another.

May happen between {{Layered World}}s or between worlds with a ThinDimensionalBarrier. See also RealityBleed for something more gradual.