Back in 1956, the Silver Age of comics began with the revival of the 1940s superhero, the Flash. After the post-war waning of superhero comics, there had been attempts to revive old heroes before, such as when Marvel published a new Captain America comic in 1954. But, with the Flash, things were different.
Not only is the new Flash, Barry Allen, a completely new character with a different costume to Jay Garrick, but also Allen’s first appearance (in Showcase #4) has him reading an old Flash comic with Jay Garrick as a fictional character. So, rather than a return, the Flash is a totally new character in a new universe with only a tangential relationship to the original.
Fast forward to 1961, when the Flash has his own ongoing comic book in our world. Now, from my understanding of the legend, superstar artist Carmine Infatino was not a fan of the character, but his covers were a big seller, so he started trying to create impossible covers for writer Gardner Fox to create stories around. So, knowing what had been established in 1956, Infantino presented Fox with a cover showing both Barry Allen and Jay Garrick as the Flash speeding to rescue the same person. The solution Fox came up with for Flash #123 was quite extraordinary for the time.
While attempting to do a magic trick for a group of children using high-speed vibrations, Barry Allen’s Flash vanishes. He suddenly finds himself in Keystone City, home of the original Flash, Jay Garrick. Barry realizes:
“I vibrated so fast—I tore a gap in the vibratory shields separating our worlds! As you know—two objects can occupy the same space and time—if they vibrate at different speeds… destiny must have decreed there’d be a Flash—on each Earth.”
Today we are familiar with the idea of multiverses, but in 1961, even the term was yet to be coined. For readers of the time, this idea would have been mind-blowing stuff. Going further, the issue claims the reason why the Flash comics exist in Barry’s universe is that some people can “tune-in” to alternative worlds via dreams. In this case, the Gardner Fox of Barry’s universe was picking up on the events in Jay’s universe in his dreams, giving him the plots of the comics he was writing. This explanation elevates the story beyond parallel universes and into metafiction.
The rest of the comic is more of a fun adventure, with Barry and Jay teaming up against some old foes, but the most important parts are the floodgates that the existence of the multiverses opened. A few months later, Jay would visit Barry’s world; in 1963, the Justice League would team up with the old Justice Society, and in 1965, Black Canary, Dr. Fate, Hourman, Starman, and the original Green Lantern all crossed paths in regular publication.
Nowadays we cannot move for multiverses of superheroes on page and screen. But it all started with the picture of a man yelling, “Flash! Help me!” and two Flashes running to his aid.