An infinity is impossible and an infinity is wrong. It's also a nihilistic concept--perhaps the most such. Consider the common modern (Hollywood) "time travel" or "relative size" explanations. Almost always aided by cool computer pictures--you know. Imagine the network of folded dimensions, temporal paths, and timelines, in which each potential variation in time produces a potential future, creating a new universe in which everything is the same except for that one choice, et cetera, producing an infinity. Imagine also the camera zooming back from a tree, showing planet Earth, then the sun, the solar system, the galaxy, all the galaxies, and then it turns out it's all just an electron inside an atom inside another tree, inside another planet, et cetera, producing an infinity of scale. Relativistic meaningless; a trap baited for expansive, rather than for small, minds.
If we conceive of an infinity in time, or of different timelines/multiverses, then nothing has any meaning, neither any given timeline nor the entire hypothetical system of timelines. Imagine the infinite continuum of choice-based and/or "butterfly effect" timelines: there are two timelines for tomorrow, one in which you do all of your normal stuff plus you poison the water reservoir, and another in which you do all of your normal stuff and you don't poison the water reservoir (not even contemplate it). In all other aspects, those particular two timelines (out of the infinite theoretical possibilities) are identical--necessarily so, because an infinity cannot be achieved without the smallest possible variations both occurring.
In such an infinity, your value as a person in the instant before you poison or do-not-poison the water reservoir is meaningless, since one of those yous poisons the reservoir while the other does not, e.g. there is no such thing as character, identity, morality, or choice. The past cannot influence future behaviors in any way, accordingly it is irrelevant whether or not you are an active reservoir-poisoner or a regular kidney donor, since infinity includes all versions of you, both the "good" and the "bad," in scenarios where the good ones as well as the bad ones feed preschoolers to a wood chipper the next day.
That's the logical conclusion of the broken falsity of infinite multiverses--the snowball rationale, if you prefer--but the meaningless of choice applies to small actions, too. If choosing to have or not have another drink of water produces a split into two different timelines, then you didn't choose, and no one has ever chosen. Not only morality, but freedom, is an illusion, in infinity, and so too in an infinity of scale as well as one of time--for, if the atoms within your bread each include a universe which includes preschools, then by eating the sandwich you are a mass murderer, but it was okay because the children were also mass murderers (for eating and thereby rearranging the universes in their own sandwiches), but it was meaningless because your own world is about to be destroyed by someone else eating a sandwich, utterly unawares. Nothing is nothing and everything is everything.
Remember this when you hear about infinities. They are cute concepts--fun, impossible nonsense for idle speculation--but evil, or if you don't care about evil, scientifically ridiculous. Infinite universes includes universes where physical laws hold true up until August 5, 2016, when they abruptly invert, or timelines where physical laws undergo a single tiny adjustment, say the rate of proton decay accelerates a mere hundredfold, ergo not only moral quandaries but observation and experiment are worthless. Reason itself is as dependent upon a lack of infinity as is morality and other such mushy stuffs.
Infinity's ascendancy in our science and entertainment has coincided, not coincidentally, with relativism, for relativism supposes and requires infinity as its logical course. Suffering from the same cross-eyed internal contradictions as diversity (e.g., we're all the same therefore we need to be diverse), relativism and infinity break on the rack of their own rules. By asking for the dismissal of time and existence, relativity's attempt to condense everything down to one impossible, indecipherable now admits that it requires objective standards of time and existence in order to have something against which to rebel. James Dean ceases to be cool once he is the establishment; so too relativity, which dies without an objective host upon which to prey.