Warning: The following article contains spoilers for Doomsday Clock #10, by Geoff Johns, Gary Frank, Brad Anderson and Rob Leigh, on sale now.
Over the past eight decades, the DC Universe has gone by a lot of different names. As alternate realities flourished around it, DC's main universe has been reclassified with distinguished monikers like Earth-One, New Earth and Earth-0, names that center on the main planet of focus in the midst of DC's various reboots.
In Doomsday Clock #10, the DC Universe gets a new name. As Watchmen's omnipotent Doctor Manhattan walks through the DC's history, he dubs it the Metaverse, a name reflecting its unique position in DC's cosmology. Instead of simply being another world in the DC Multiverse, the Metaverse sits above all the other realities, where any changes to it ripple across all of the dimensions beneath it.
While the word 'metaverse' has been infrequently used to describe the magnitude of DC's multiversal order, Manhattan's use of the name here acknowledges the DC Universe's special place in DC's cosmic order, since the prefix "Meta" means beyond here. And though the term has been used on occasion to describe the magnitude of DC's multiversal order, he's also naming the universe for its defining feature, metahumans.
In most modern incarnations of the DC Universe, any person with powers that are beyond regular human abilities is referred to as a metahuman. Within DC continuity, the term was originally coined by the Dominators, a group of alien invaders studying why humans develop powers in 1986's Invasion! #1, by Keith Giffen, Bill Mantlo and Todd McFarlane.
Originally, the term was specifically used to describe human individuals who developed powers, like the Flash, Firestorm or Poison Ivy. Since then, the term has been applied more broadly to anyone with superpowers, even to aliens like Superman.
By any definition of the term, Doctor Manhattan would be considered a metahuman. As Alan Moore and Dave Gibbons detailed in Watchmen #4, Manhattan developed his powers after being trapped in an intrinsic field generator.
While that kind of origin is relatively common in the Metaverse, Manhattan has been portrayed as the only metahuman in the world of Watchmen. Accordingly, the existence of DC's metahumans has both fascinated and perplexed Manhattan throughout Doomsday Clock.
In Doomsday Clock #10, Manhattan travels to April 18, 1938, the day when Superman's debut by Jerry Siegel and Joe Shuster was published in the real world in Action Comics #1. In the Metaverse, Superman made his public debut as a superhero on that day, and introduced his world to the concept of super-powered individuals.
After seeing the ripple effects Superman's introduction caused throughout time, Manhattan went on to identify the Man of Steel as the central figure of the Metaverse.
In both the Metaverse and the real world, a legion of metahumans emerged in the wake of Superman's debut. Although the rise of metahumans has often gone unquestioned in the DC Universe, Doomsday Clock has interrogated the idea with the Supermen Theory.
According to the Supermen Theory, the United States government covertly engineered the creation of metahuman heroes and villains, which is why the U.S. is home to a disproportionate number of the world's metahumans.
While this information kicked off an international metahuman arms race, it also makes the idea of metahumans central to history of the DC Universe to a degree that it hasn't been before.
Even though they're arguably the two biggest plot points in the series, Doomsday Clock hasn't yet made an explicit connection between the Supermen Theory and Doctor Manhattan's tampering with the Metaverse's history.
In their own ways, both of those ideas are examinations of how important the idea of metahumans is to the larger Metaverse. Although neither of those investigations is quite over, Manhattan has already renamed the DC Universe, in part, to affirm the centrality of its super-powered residents.