According to some, the idea of infinite worlds was first suggested by the pre-Socratic Greek philosopher Anaximander in the sixth century BCE. However, there is debate as to whether he believed in multiple worlds, and if he did, whether those worlds were co-existent or successive. The first to whom we can definitively attribute the concept of innumerable worlds are the Ancient Greek Atomists, beginning with Leucippus and Democritus in the 5th century BCE, followed by Epicurus (341-270 BCE) and Lucretius (1st century BCE). In the third century BCE, the philosopher Chrysippus suggested that the world eternally expired and regenerated, effectively suggesting the existence of multiple universes across time. The concept of multiple universes became more defined in the Middle Ages. The American philosopher and psychologist William James used the term "multiverse" in 1895, but in a different context. The concept first appeared in the modern scientific context in the course of the debate between Boltzmann and Zermelo in 1895. In Dublin in 1952, Erwin Schrödinger gave a lecture in which he jocularly warned his audience that what he was about to say might "seem lunatic". He said that when his equations seemed to describe several different histories, these were "not alternatives, but all really happen simultaneously". This sort of duality is called "superposition".
Based on the given text give the name of the people and a summary of how they contributed to the notion of infinite or multiple worlds.
Here are the name of the people and a summary of how they contributed to the notion of infinite or multiple worlds:

Anaximander (6th century BCE): The idea of infinite worlds was first suggested by him.

Leucippus (5th century BCE), Democritus (5th century BCE), Epicurus (341-270 BCE) and Lucretius (1st century BCE):  They believed in the concept of innumerable worlds.

Chrysippus (3rd century BCE): He suggested the existence of multiple universes across time which means the world eternally expired and regenerated.

William James (1895): He first used the term "multiverse". 

Boltzmann and Zermelo (1895): In a debate between them the multiverse concept first appeared in the modern scientific context.

Erwin Schrödinger (1952): He first came up with the term "superposition" by referring to his equations that seemed to describe several different histories which were "not alternatives, but all really happen simultaneously".