Schrodinger was responding to the quantum theories of Albert Einstein and his pals. One thing they said was that the state of a quantum thing is not determined until it is observed and the observation itself affects the outcome. That's a bit simplistic, but let's not get into the details here. Schrodinger proposed a situation in which a cat is inside a metal box and possibly exposed to a poison dependent on the half life of a radioactive atom. The fate of the cat is not determined until the box is opened and the observer observes whether the cat is dead or alive. So, as long as the cat is inside the metal box unobserved, the cat is both alive and dead.
Schrodinger's Cat led many to propose theories based on this thought experiment. One theory was that there are multiple realities. In one reality when the observer observes the cat as alive, reality splits to a world where the cat is alive, but another reality also exists where the cat is dead.
With Krona (dc comics charachter..one of the alien race of guardians,a scientist who became obsessed with observing the origins of the universe itself, despite an ancient legend that said discovering that secret would cause a great calamity ) attempting to observe the beginning of the universe, the very action of observation collapses possibility and determines the quantum reality--in which then all the universe exists. Observing something that cannot be observed changes the outcome. From this the DC Universe takes shape, but so also does the Multiverse. If the act of observation determines one outcome, then another outcome is also possible. And so begins the cascade of alternate realities that creates the Multiverse.
Even in our own reality, by simply observing phenomena, we may actually be determining reality, which up to that point is indeterminant.
One of my favorite runs of one of my favorite comic book series is "Schrodinger's Pizza." in Animal man by write Peter Milligan.