IN AN INFINITY of universes, an endless number of possibilities must exist, as Max Tegmark argues in "Parallel Universes" [May]. It's tempting to wonder if every other Scientific American board of editors who published that article got as bleary-eyed reading the scads of letters it generated. Many of the notes were thoughtful--and thought-provoking--such as this one, which Anita Brubaker sent via e-mail: "If Tegmark's multiverse theory is true, then one of the many existing universes has no pain, no death and no suffering. On the other hand, one universe's inhabitants experience maximum pain. Has Tegmark demonstrated the existence of what are usually called heaven and hell?" More cosmic commentary on the May issue follows.
This article was originally published with the title Letters.