Basic Information
Scientifically speaking, other dimensions would likely be just a "bigger picture" in terms of movement, measuring, space, physical interactions, and perception, like Edwin Abbot Abbot's Flatland. See Spatial Dimension, Fourth Dimension and Fourth Dimensional Lifeform for details. It's pretty cool, but what scientists mean by "dimension" is not really what most sci-fi media use the term to mean.
In fiction, other "dimensions" are generally presented as alternate realities. Another Dimension is speculative fiction trope that refers to another world or reality that is somehow convergent, divergent, or parallel to our own. To travel from this dimension to another dimension you need some sort of Magic, Applied Phlebotinum or at least some really good Technobabble. All kinds of craziness can happen in another dimension.
The TV Tropes Wiki takes the position that the difference between Another Dimension and an Alternate Universe is that the other dimension might have very little in common with our home universe, whereas the Alternate Universe is typically some sort of parallel world. As mentioned above, that's not a very scientifically sound definition, but I suppose it's good enough for Hollywood Science.
Related Tropes:
- Alien Geometries
- Alternate Universe
- Beneath The Earth
- Demonic Invaders
- Inn Between The Worlds
- Lost World
- Magical Land
- Mirror Universe
- The Multiverse
- Portal Network
- Transporters and Teleporters
See Also:
- Alternate Reality
- Dimension
- Dimensional Gate
- Dimension Hopping
- Fairy Realm
- Fictional Locations
- Metaphysical Place
- Multiverse
- Mythological Places
- Otherworld Tropes
- Plane of Existence
- Summoning
- Teleportation
- Time Travel
- Vortex
Sources
Game and Story Use
- Fun place to send the players.
- Convenient point of origin for monsters and NPCs.
- The sky's the limit! …Or actually, you can surpass the sky. That's kind of the point.