Editing Marvel Universe (section)

===Time===
{{unreferenced section|date=September 2014}}
One cannot normally alter the Marvel Universe's history; if a time-traveler should cause an alteration to the established flow of events at some point in the past, a [[Parallel universe (fiction)|divergent universe]] will simply "branch out" from the existing timeline, and the time-traveler will still return to his or her unaltered original universe. Those realities can also spawn realities of their own. There exist hundreds, probably thousands of such realities. It is unknown why this happens, though a warp known as the Nexus of All Realities exists in a swamp in the Florida Everglades of Earth-616. For the most part, this does not matter, as most beings are unaware that this occurs, or even that their universes were recently "born" from another. However, individuals and organizations exist that try to monitor or manipulate the various realities. These include [[Immortus]], the [[Captain Britain|Captain Britain Corps]], the [[Time Variance Authority]], the [[Timebreaker]]s/[[Exiles (Marvel Comics)|Exiles]], and [[Kang the Conqueror]]'s forces. It is possible to travel through time without creating a new alternative universe, instead of altering events in the future, but this seems to have devastating and very far-reaching repercussions, as depicted in [[Marvel 1602]] (it almost destroyed the whole multiverse, including the [[afterlife]]).{{citation needed|date=September 2014}}

Also, time itself passes much differently within the confines of the Marvel Universe than it does in the real world. Despite various characters having appeared within company publications for decades, few, if any, have aged to any appreciable degree. For example, the patriotic hero [[Captain America]] was created in 1941 but stopped appearing in titles soon after the end of [[World War II]]. The character was revived more than 20 years later, explained as having been frozen in a block of ice though believed to be dead, to lead Marvel's latest team of superheroes the [[Avengers (comics)|Avengers]]. This first Avengers team featured several characters that would go on to be some of the company's most famous and most popular. Although the characters would be portrayed in hundreds and even thousands of adventures over the decades, they have been portrayed as having aged little or not at all.{{citation needed|date=September 2014}}

Naturally, this tendency is purely due to story conveniences (or a somewhat haphazardly shifting patchwork pattern of authors), and mainly that the fictional "continuity" has been maintained and expanded far beyond what [[Stan Lee]] and others originally planned or hoped for. Hence, the passing of time was more discernible in the very early years, such as the graduation of [[Spider-Man]]; and what started as children or teenaged characters, such as [[Kitty Pryde]], [[Franklin Richards (character)|Franklin Richards]], [[Valeria Richards]], [[Power Pack]], or the [[New Mutants]] are all allowed to age at wildly shifting rates (in the second case even backward at times), whereas surrounding characters somewhat dependent on a certain age limit do not change at all. This recurrently creates inherently contradictory effects, as events are routinely described to have happened several years ago, even in cases when this would mean that some of the involved characters would have been toddlers. Different approaches also exist regarding allowing "second-generation" descendants of heroes or villains, full-grown over 18 years after an event (for example, [[Hulkling]], other members of the [[Young Avengers]], the [[Runaways (comics)|Runaways]], and the [[Secret Warriors (Team White)|Secret Warriors]]), whereas other books, such as ''[[Young Allies (Marvel Comics)#Heroic Age|Young Allies]]'' use the inherent contradiction to debunk similar claims. If a past storyline wherein a direct depiction of a then-current president or similar is referred to in a later era, it tends to become updated accordingly, sometimes with an "in-joke" acknowledgment.{{citation needed|date=September 2014}}

A more recent explanation was given by Galactus to the Ultimates, namely that some important events – for instance, the creation of the Fantastic Four or the Avengers –  have a 'gravity' all their own and warp time around them, causing the timeline to subtly change to accommodate this.<ref>''Ultimates'' (2015) #5</ref>