A boom tube is a slang expression for a fictional extra-dimensional point-to-point Einstein-Rosen bridge (a form of teleportation) opened by a Mother Box used primarily by residents of New Genesis and Apokolips in DC Comics. The concept was created by Jack Kirby for his Fourth World series of comics.
The "science" of boom tubes has never been explained (as is normal for the New Gods, though Orion, in the first issue of New Gods, says that a tube "stems from the waves of the mind") but they allow people to quickly travel interstellar distances, and between dimensions, by creating an apparent tube between two points through which people can travel. When used, a low humming accompanies the formation of the "tube" (a tunnel of rippling circles of light) which increases in volume as the tube is maintained and traversed, ultimately culminating in a loud "booming" noise when it closes. This "boom" has been known to knock bystanders off their feet and shatter glass, and gives the technology its name. The tubes are generated or opened by another device, a Mother Box. Boom tubes are powered by the mysterious X-element, which serves as a matter threshold.
The initial Kirby comics depict boom tubes as a sort of quasi-technological equivalent of Bifröst, the Rainbow Bridge linking Asgard and Earth; indeed, boom tubes are described as a "bridge to Earth." Subsequent writers have allowed the tubes to be used for point-to-point transport between various locations on New Genesis, Apokolips, Earth, and other planets, thereby making them near-ubiquitous for the travel of the New Gods.
The "tubes only" idea was reinforced when later writers introduced the idea that the New Gods were, in fact, giants, and that the boom tube would appropriately shrink or enlarge people who traveled through it. The precise size ratio has varied, with New Gods in their "original" size being depicted as anywhere from tens of feet tall, to tens of thousands of miles tall (as in New Gods #10, 1996).
In Brad Meltzer's Justice League of America #1, a villain named Doctor Impossible uses a "father box" to summon "hush tubes".
Outside of the comic books, boom tubes have been seen on a number of occasions. They are first seen in the last two seasons of the Super Friends animated series, Super Friends: The Legendary Super Powers Show and The Super Powers Team: Galactic Guardians on a number of occasions. Here, they are referred to as "Star Gates," and they are used by the natives of Apokolips, though without the sonic boom caused by boom tubes. New Genesis was never shown or mentioned.
In the Legends miniseries they are also referred to as "star gates".
The DC Animated Universe incorporated the Boom Tubes in their shows: They were first seen in Superman: The Animated Series, as well as Justice League, Justice League Unlimited, and Batman Beyond.
In the Legion of Super-Heroes television series, Superman X uses a device similar to a Mother Box called a "warp key" to open a portal to the past to recruit the Legion of Super-Heroes to battle Imperiex.
Boom tubes appear briefly in the video game Mortal Kombat vs. DC Universe as one of many transportation methods used. In the first scene of the DC Universe side of the story, Darkseid attempts to escape defeat in Metropolis via a boom tube. However, Superman blasts him with a heat ray as he enters the boom tube, coinciding with Raiden of the Mortal Kombat multiverse blasting Shao Kahn with a lightning blast as he enters a portal in another plane. The cosmic coincidence of Darkseid and Shao Kahn using similar portal-like apertures simultaneously combined with the also simultaneous energy discharge from the respective protagonists' attacks results in the being Dark Kahn, the antagonist of the game.
The Boom tubes are featured in the DC Super Hero Girls TV special "Super Hero High".
