The word "portal" in science fiction and fantasy generally refers to a technological or magical doorway that connects two distant locations separated by spacetime. It usually consists of two or more gateways, with an object entering one gateway leaving via the other instantaneously.

Places that are linked by a portal include a different spot in the same universe (in which case it might be an alternative for teleportation); a parallel world (inter-dimensional portal); the past or the future (time portal); and other planes of existence, such as heaven, hell or other afterworlds. A parallel world, such as the Wood between the Worlds in C. S. Lewis's Chronicles of Narnia, may exist solely to contain multiple portals, perhaps to every parallel world in existence.

Portals are similar to the cosmological concept of a wormhole, and some portals work using wormholes.

Use

Portals are often used in science fiction to move protagonists into new territory. In video games the concept is often used to allow the player to cover territory that has already been explored very quickly. A related book plot that is commonly used is the struggle to get to the opposite end of a new gate for the first time, before it can be used.

Film and television

In film and television, a portal is often portrayed using a ripple effect.

• Star Trek: The Original Series: One of the earliest examples is the Guardian of Forever, in Star Trek. The device could open a spacetime portal to any point in history on any world in the universe. It was ring-shaped, with a watery "event horizon". This device was introduced in the Star Trek: The Original Series episode "The City on the Edge of Forever" in 1967.

Other examples of portals include:

• Buck Rogers in the 25th Century (TV series): Portals appeared in the series Buck Rogers in the 25th Century (1979–1981), where interstellar travel was facilitated by a network of portals.
• Cowboy Bebop: In the anime Cowboy Bebop, hyperspace gates allow for faster—though not instantaneous—travel between the planets and colonies of our solar system.
• Donnie Darko: In the movie Donnie Darko a portal appears on a cinema screen.^[1] A fictional book within the film (Philosophy of Time Travel) serves as the basis for fan theories about time travel, parallel universes and portals.^[2]
• Doraemon: A more lighthearted use of portals can be found in the Japanese comic and anime series Doraemon, where the Anywhere Door is used to travel from any point to another. This door looks like and operates like an ordinary household door.
• The Final Countdown (film): In the movie The Final Countdown, the aircraft carrier USS Nimitz is transported via a portal to 1941, where its Captain must decide whether to intervene in the Pearl Harbor attack.
• He-Man and the Masters of the Universe: In the cartoon series He-Man and the Masters of the Universe and She-Ra: Princess of Power the characters are able to travel through time and space by using magic space portals and time corridors. They can be used by characters with magic abilities, and are usually of a yellow colour. Sometimes they can have a pink or purple appearance. In some instances a portal allows travel from one place to another in just a few moments. In other cases (the She-Ra-Episode "Darksmoke and Fire"), the user travels through a separate dimension and can change his destination en route.
• Gargoyles: Two types of portal existed in Disney's mid-1990s Gargoyles animated fantasy adventure series; one was usable from any body of water while in a boat of any size, and took the traveler(s) to the series' depiction of the enchanted island of Avalon through the reciting of the Latin-language "Avalon spell",^[3] while the other was through the use of the fictional, enchanted "Phoenix Gate" artifact, which took the traveler(s) to any time and place that the person that held the device was thinking of when they recited a different Latin-language spell to activate the artifact's occult powers.^[4]
• Gravity Falls: In Gravity Falls, Dipper and Mabel's Great Uncle Ford constructed a portal underneath the Mystery Shack. It was used by his twin brother Stan to bring him back from an unknown dimension.
• Howl's Moving Castle: In the Hayao Miyazaki film Howl's Moving Castle, based on the novel by Diana Wynne Jones, Howl's castle has a door with a four color dial above it, and each color setting causes a different location to appear on the other side of the door, only one of which is immediately outside the castle.
• Jackie Chan Adventures: In the cartoon series Jackie Chan Adventures, eight demons were sealed away using portals to trap each of them in a different realm. The portals could be opened again. The demons were released but later recaptured and returned in the netherworld. A spell was used on each portal to seal it forever, ensuring that the demons could never escape again.
• Jak and Daxter: "Warp gates" in Jak and Daxter are rings enclosing a rippling blue substance used for transportation.
• The Legend of Korra: In The Legend of Korra, the two spirit portals, located in the north and south poles, connect the physical world and the spirit world, allowing passage to the spirit world without meditation. However, a new portal was created in the center of Downtown Republic City after Kuvira's sprit energy weapon overloaded.
• Lost in Space (film): The 1998 film Lost in Space featured a space-bound hypergate system. The premise of the film is that the Robinson family will pilot a spaceship to Alpha Centauri to construct a receiving hypergate, allowing instantaneous travel between Earth and Alpha Centauri.
• Mighty Max: In the Mighty Max television series and toyline, the titular character Max receives a magical baseball cap capable of projecting wormhole-like portals that allow Max to teleport across time and space and even travel to alternate dimensions and the astral plane.
• Monsters, Inc.: The animated film Monsters, Inc. involved portals that open through children's closets. This enabled the inhabitants of the monster world to enter children's bedrooms and cause them to scream. Children's screams are the power source of the monster world, and are siphoned through the portals into containers for refinement. Each portal is an exact replica of a child's wooden closet door in a metal frame, allowing a monster to enter that child's room. Some portals have metal doors and open to counterparts in remote locations in the human world. The finale features a wild chase through a massive gallery of closet door portals, causing jumps between places such as Paris, Japan and Tahiti.
• ReBoot: A portal in ReBoot, created by the villainous character Megabyte, displays a rippling event horizon.
• Starcraft (series): The StarCraft series features warp gates that are similar in style and function.
• Stargate Franchise: The Stargate franchise uses wormholes as one of the primary methods of travel between planets. Large rings are placed on, or in orbit around planets throughout the universe. When the travelers "dial" the address of their destination, a wormhole is formed between the two Stargates.^[5]
• Star Trek: The Next Generation: Star Trek depicted devices called "Iconian Gateways" with angular frames and ripple effects such as the one in the Star Trek: The Next Generation episode "Contagion".
• Star Trek: Voyager: In Star Trek: Voyager and the game Star Trek: Armada II, the Borg have a technology known as the transwarp conduit. The aperture of the conduit at the transwarp hub resembles the event horizon of a Stargate crossed with the wormhole effect created by the Stargate.
• Star vs. the Forces of Evil: In the animated television series Star vs. the Forces of Evil, characters open portals to other dimensions using Dimensional Scissors.
• Portals are prominent in the 1987–1996 Teenage Mutant Ninja Turtles cartoon, as a method of transportation between distant locations and even through time. The most famous portal of the series is inside Krang's Technodrome but from the third season, Donatello also develops a portal generator.
• Transformers: In Transformers, the Decepticons built the Space Bridge, which serves a similar purpose. A large round ring built on Earth (lying flat) would create a subspace tunnel to a destination tower on Cybertron. One key difference in function was that matter was not broken apart for transport.
• Treasure Planet: In Treasure Planet, the portal (also referred to as "a 'big door' opening and closing") is an enormous energy doorway that allows practical, rapid travel between two distant locations anywhere in the universe. The spherical map (holographic projector) that led to Treasure Planet also worked as the portal's control panel once plugged into a keyhole and would project an orbital list of locations. One touch on one of the projected destinations and the portal would instantly open a doorway to that destination, large enough for a ship to pass through. It is possible that the portal was built by the ancient alien race that created the map and the planet itself (which is actually a large, spherical mechanism composed of incredibly advanced technology).
• Imaginationland: The Movie: In Imaginationland: The Movie, the boys are told of a portal into Imaginationland that had been built during the Cold War and is controlled by the government. The Pentagon decides to send a group of soldiers into Imaginationland through the portal.
• My Little Pony: Friendship is Magic: In the fourth generation of My Little Pony, portals are often depicted as rifts through space and time, and can be opened by a being with powerful magic, or with specific powerful magical items (such as the Elements of Harmony). These portals can be used for transportation between universes (as is the case in the Equestria Girls series of My Little Pony); or can be used for banishment (as seen in the season 8 episode, Shadow Play^[6][7], and in Equestria Girls: Rainbow Rocks)

Literature

In his Hyperion Cantos novel series, Dan Simmons imagines a network of portals called "farcasters" which connect most human-inhabited planets. The form these portals take can vary, and they may be opaque, completely transparent, or semi-transparent. The completely transparent variety is very commonly used and effectively turns all connected places into one giant WorldWeb where distance becomes almost meaningless. Some of the more opulent occupants may have houses where each room is built on a different planet, and some rooms themselves may be partially built in several different physical locations but be joined by farcaster portals to form one complete room.

Stephen Robinett's book Stargate^[8] (1976) revolves around the corporate side of building extra-dimensional and/or transportational stargates. In the novel, the stargate is given the name Jenson Gate, after the fictional company that builds it. Andre Norton's 1958 novel Star Gate may have been the first to use that term for such portals. The plot of Robert A. Heinlein's Tunnel in the Sky (1955) uses a portal. Raymond Jones' Man of Two Worlds (aka Renaissance) (1944) employs a portal that turns out to be a fraud.^[9]

The Shi'ar, an extraterrestrial race introduced by Marvel Comics in 1976, also utilize a network of stargates. The Shi'ar utilize both planet-based stargates (for personal travel) and enormous space-based versions (equivalent to the Ori supergate and used as portals for spaceships), though both are usually depicted without any physical structure to contain the wormhole. They are used for travel across great distances.

In the His Dark Materials trilogy, Philip Pullman has characters use the 'subtle knife' to carve a doorway from one world to another. CJ Cherryh's Morgaine series see the main characters travelling via 'gates' from world to world, closing them as they go.

Since the introduction of the stargate on the big screen other authors have referenced the stargate device. Authors Lynn Picknett and Clive Prince also write of The Stargate Conspiracy: The Truth About Extraterrestrial Life and the Mysteries of Ancient Egypt. The book details an alternative theory links the term stargate with Egypt's past: Either the pyramid itself is a gateway to the stars (because of the shafts pointing to a star) or a construction of Heaven on Earth based on geographical location of the great and outlying pyramids (see: Orion).

Games

Stargate-like devices, referred to as warp zones, are abundant in video games, as they can be used to split a game neatly into levels. The video games Primal and Turok the Dinosaur Hunter feature gateways allowing instantaneous travel between locations to this effect. In Metroid Prime 2: Echoes, a number of ring-shaped dimensional portals allow the main character to travel between Light and Dark versions of the planet Aether. In the game EVE Online, a large object called a "stargate" lets the player travel between solar systems, and in Homeworld 2, Hyperspace Gates serve as the centerpiece of one of the game's final missions, in which massive rings create wormholes capable of transporting matter great distances. In Super Mario 64 and its follow up, Super Mario Sunshine, various paintings and warp pipes lead to levels, all connected by a bigger level that houses these portals. Portals are used frequently throughout the Spyro (series), with each individual level, or world, separated by portals, allowing for loading screens which do not damage the games immersion.

In "Bioshock Infinite", Elizabeth is able to open up portals ("Tears") from another period of time either future or past, in an alternate dimension of their world.

In the Half Life franchise, Combine forces use portals to travel to Earth from Xen, a parallel plane of existence.

In Command and Conquer 3: Tiberium Wars, the alien race Scrin uses portals to transport their armies onto and across the battlefields. The description of their Gravity Stabilizer states that the structure compensates for Earth's intense gravity and magnetic field, "allowing Alien spacecraft to execute short-range teleportation jumps directly to the battlefield".

Portals are common in MMORPGs. In RuneScape, portals can be used domestically. Players can install portal chambers in their houses that link to different cities in the world, allowing free transport to these places for both them and any visitors to their houses.^[10] In World of Warcraft, mages can summon portals that can teleport the mages and their group members to various cities.

In the augmented reality game Ingress portals are placed at sculptures, statues, and other public art, unique businesses, and historically and architecturally significant buildings and the like, but serve as nodes in the game mechanics (see graph theory) without any transportation function.

The game Portal and its sequel, Portal 2 created by Valve Corporation features a portal-creating device, known as the Aperture Science Handheld Portal Device, as a central game mechanic which is used to solve puzzles and reach otherwise-inaccessible destinations. The portals are depicted with few special visual effects; instead, they are shown as representations of the destination, bordered by blue or orange particle effects. In the video game Half-Life, portals are displayed as glowing balls of energy which instantly teleport the user to an inversely colored exit point.

In the game Minecraft created by Markus Persson and Jens Bergensten, it is possible to build a portal to an alternate hell-like dimension called "The Nether".^[11][12] It is accessed by making a frame of obsidian blocks, with a 3×2 rectangle in the centre, then setting it on fire using any object that can make fire. When lit, the frame will be filled with blocks resembling whirlpools. A player standing in the portal long enough will be transported to "The Nether," which consists of caves, lava, fortresses, mushrooms, neutral zombie pigmen, magma-slime creatures, tall black "wither skeletons", and fire shooting "ghasts" and "blazes". Another kind of portal in "Minecraft" is the End Portal, which is a portal found 128 (only 3 in the console version) times in "Strongholds" throughout the world. The players use "Eyes of Ender" to find the End Portal, and places one Eye of Ender in each frame block (if not already there). When completed and entered, the player will go the "End", filled with mobs called "Enderman". The only way out of the End is to either get killed or kill the Ender Dragon, which opens a portal back to the Overworld.

The role of a portal serves the tunnel network of GLA in the game Command and Conquer Generals. This is a building that can garrison some units. These units can exit from every tunnel network of their base without any relay. It is supposed that they travel underground with relatively high velocities, but they seem to be teleported.

See also