SPOILER WARNING: The following article contains major spoilers for Doomsday Clock #11 by Geoff Johns and Gary Frank, on sale now.
The evidence of Doctor Manhattan's meddling with reality is mounting in Geoff Johns and Gary Frank's Doomsday Clock. Among those who've come to realize that something is amiss is Lex Luthor. Luthor's been stockpiling photographs to support this notion -- photographs from realities that don't exist, thanks to Manhattan.
In Doomsday Clock #11, one of those photos recalls a classic moment in DC history -- one that readers have seen before, even if its unfamiliar to the occupants of the DC Universe.
That photo captures the defining moment when The Flash (Barry Allen) first met The Flash (Jay Garrick) in Gardner Fox and Carmine Infantino's The Flash #123 from 1961. That landmark story, titled "The Flash of Two Worlds" introduced the concept of the multiverse to DC continuity and marked the first-ever meeting between a DC hero and his Golden Age counterpart.
The the photo is shown in this issue's post-story supplemental material. The photo of the two Flashes is unique, as it's part of Luthor's collection of other photographs -- different photos that all contain the same common image. That image shows a younger, pre-Doctor Manhattan Jon Osterman and his then-girlfriend Janey Slater. That particular photograph was first seen in Watchmen, inadvertently discarded by Manhattan on the surface of Mars.
Those photos have been left like "breadcrumbs," according to Luthor, in various locations around the Earth where Manhattan has appeared to alter reality. One of those was left in Central City, where Luthor also found the photo of the Flashes. Luthor also calls the photographs "chronal debris" -- remnants from realities that no longer exist after Manhattan has altered them.
In current Rebirth continuity, Jay Garrick never became the Flash, although the exact reasons behind that are unknown. Doomsday Clock #7 showed that Manhattan deliberately prevented Alan Scott from becoming the first Green Lantern, and in turn preventing the formation of the Justice Society of America. Whether Manhattan also directly interfered with Garrick's fate, or whether that fate was secondarily altered by the absence of Green Lantern, is unclear.
Luthor's discovery of the Flash photo indicates that Manhattan had made his way to Central City at some point. This could likewise indicate some deliberate actions against Barry Allen on Manhattan's part, although not necessarily against Garrick. The presence of the photo, though, hints that Manhattan might have taken some reality-changing action against both Flashes.
Regardless, the fact that the photo exists shows that the fateful encounter between the junior and senior Flashes "happened" -- at least somewhere in reality. If Manhattan is eventually defeated and reality can right itself again, that moment stands to become canon again -- not merely "chronal debris."