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A floating timeline (also known as a sliding timescale) is a device used in fiction, particularly in comics and animation, to explain why characters age little or not at all over a period of time - despite real-world markers like notable events, people and technology appearing in the works and correlating with the real world. A floating timeline is a subtle form of retroactive continuity. This is seen most clearly in the case of comic book characters who debuted as teens in the 1940s or the 1960s but who are still relatively young in current comics. Events from the characters' pasts are alluded to, but they are changed from having taken place years ago to having taken place more recently.
Any dates given within the comic are not relative to the publishing date of the comic (i.e. "10 years ago" means "10 years before you read this"). This device enables publishing companies to continue to use their characters for as long as they wish without changing them significantly. If used completely, the floating timeline allows all the volumes of a series to be viewed in any order while still maintaining a solid perception of the plot. A floating timeline is usually abstracted from that of actual historical events, but may contain subtle references to the real world timelines.
The use of a floating timeline in comics often requires drastic revisions of a character's history, since many comic books are produced over a time period measured in decades.
Marvel Comics 
For instance, in 1960s comics by Marvel Comics, the character the Thing states he fought in World War II. However, in comics in the 2000s (decade), the Thing states that the idea of him fighting in World War II is ridiculous, as he would have to be much older.
A variation of the floating timeline effect was used in the Fantastic Four comics when run by artist John Byrne in the 1980s. In these stories, characters appeared celebrating Christmas in the December issue and then, four issues later, they appeared in full Spring, although the events had happened just a few weeks ago in the storyline. This may be called "seasons shift" in periodical publications such as comic books.
Another example can be found in Iron Man's origin. Tony Stark creates his first armor to escape his captors. In the character's first story, this event took place during the Vietnam War. Then, in the 1990s, it was updated to the first Gulf War, and in the 2000s (decade), it was depicted as having taken place in Afghanistan. While the specifics of the event never deviate from the canon, the place and time are updated, reflecting the real-world age it was published in and also preventing Stark from aging.
DC Comics 
Another example is the DC Comics character Wonder Woman. Wonder Woman was a heroine in 1950s comics; however, recent DC publications imply that she began as a hero in the mid-to-late 1980s. The fact there was a Wonder Woman in the 1940s is later explained by the retcon that Diana is the second Wonder Woman, having inherited the mantle from her mother, Queen Hippolyta.
In the DC multiverse, alternate explanations have been introduced for such enigmas; in the 1960s, it was shown that the stories from various eras took place in different parallel universes. The Wonder Woman of the 1940s, for example, is not Hippolyta but an alternate-reality Diana. Later, in a series of stories entitled Crisis on Infinite Earths, they were consolidated in a single universe from which a new timeline started over.
Such a timeline often creates confusion due to major historical events such as World War II or the Vietnam War, which many characters, such as various members of the Justice Society of America, need to be based on. It seems that only storylines (apart from those based on real-world events such as 9/11, World War II, etc.), character designs, and dialogue abstracted from current affairs are truly canon, though as many of these fade into the distant past, it remains to be seen whether characters will be tied to these origins still or retconned for a more recent war. For example, shortly after 1986's Man of Steel miniseries, Superman's adopted father, Jonathan Kent, was revealed to have fought in World War II in the mini-series The World of Smallville. Later, in the aftermath of 1993's Death of Superman he is said to have fought in the Korean War.
Batman's origin often shows his parents murdered in 1930s or 1940s fashions, while the adult Bruce Wayne clearly lives in the present (this is shown in fashion and technology). In The Return of Bruce Wayne #5, Batman travels in time to shortly after his parents were murdered. The 1930s-style clothes and cars are explained by a character who informs him that "retro is big this year," keeping the iconic image but being vague about the actual year.
The Phantom 
The Phantom is known to be "The Man Who Cannot Die" and "The Ghost Who Walks" since it's a well kept secret that the persona of the Phantom is inherited from father to son. The Phantom still uses a floating timeline which makes it possible for the 21st Phantom to be married to Diana, have slowly aging children and keep his best friend Guran the same age.
The Adventures of Tintin 
The Adventures of Tintin have a floating timeline spanning the period of 1929 to 1976, set invariably in the present of the respective episode's creation, as is visible from technology (cars, planes etc.) as well as alluding to current-day events of the interbellum and the rise of fascism, and later the Cold War and the space race, while references to World War II itself are conspicuously absent from those episodes created during the war when Belgium was under German occupation.
Another famous example is Archie Comics, in which all the characters have remained the same age since its inception in the 1940s, but have been adapted regularly to show current trends and fads. Archie Andrews and his friends have been high school teenagers since they were first introduced in 1941.
Syndicated Comics 
This effect is also seen in most syndicated comic strips and, in some cases, is even mentioned by characters. For example, in a certain FoxTrot strip, Andy remarks to Jason "You can stay 10 sweetie, I don't mind." Likewise, in one early Calvin and Hobbes strip, Calvin's unwillingness to live in the moment is criticized by his father, who says: "Yeah, I know. You think you're going to be six years old all your life." Indeed, throughout the strip, Calvin remained six years old, with the character Susie Derkins being the only character in Calvin and Hobbes to have a (shown) birthday.
A different kind of floating timeline occurs in Peanuts. As most established characters are young children, characters initially introduced as babies (such as Sally Brown) age to roughly match their counterparts but then cease to.
Continuity-based webcomics often exhibit floating timelines as well; the webcomic 1/0 often mentioned the fact that an hour from the characters' perspective could translate into months to the author and readers, while Megatokyo, since the end of its first year, has had just over one day of in-comic progress per real-world year. Thus, for instance, preview posters for Metal Gear Solid 2 and Metal Gear Solid 4 have been seen within mere months of one another. The comic Least I Could Do had a floating timeline until the July 9, 2007 strip, in which the cast opened a "letter" from the writer and artist which stated that from that moment on, they would age normally rather than remain a perpetual age 24 or so.
Live action 
Doctor Who 
Due to the show's use of time travel as a major plot element, Doctor Who has on many occasions visited a past year which was still the future at the time of the story's writing. For example, various contemporary stories from the original series which were set in their respective decades feature Earth actively involved in interplanetary travel. Later episodes, the new series, and the series Torchwood are written assuming real-life progress in space travel. The UNIT dating controversy is an attempt to explain the confused timeline and the technology seen during those episodes, as well as the inconsistently maintained time setting depicted within those episodes. Tongue-in-cheek references to the problem were made in the The Sarah Jane Adventures spin-off  and, subsequently, on Doctor Who itself.
In the series' revived era, an extra year was created when the program jumped ahead by a year in 2005. By 2007, both Doctor Who and its then-new spin-offs Torchwood and The Sarah Jane Adventures had re-established present-day in 2007 despite Doctor Who having depicted two successive Christmases and myriad months of events that remained in-sequence.
M*A*S*H, a TV series set during the Korean War, lasted eleven years, while the actual war lasted only three. The members of the 4077th celebrated Christmas and Thanksgiving more times than the actual conflict would have allowed. In addition, some characters length of service in the military seems to vary, often wildly. When Colonel Potter, for example, takes command of the 4077th, the date is stated as 1952, however a later episode shows him hosting a New Year's Eve party in 1950. Compounding this, Alan Alda's character, Hawkeye, claims to have been stationed in Korea for two years, long before Potter takes over from Colonel Blake. Also, the characters of Frank Burns and Charles Winchester both, at separate points, claim to have been serving at the M*A*S*H for two years, despite Charles having been Frank's replacement and the two never having served together.
One Tree Hill 
The drama series One Tree Hill used a floating timeline as well. The first four seasons of the show focus on the main characters' lives through two high school years. With the beginning of the fifth season, Schwahn decided to skip the timeline four years ahead, showing their lives after college. In the seventh season, he adjusted the timeline fourteen months into the future after the sixth season. In the eighth season finale episode, a whole year goes by. The last time jump appeared in the series finale in 2012, when the show skipped around another seven years. In the end, this means that One Tree Hill covered about seventeen years in its nine seasons.
Upstairs, Downstairs 
The British drama series Upstairs, Downstairs also used a floating (and at times anachronistic and uneven) timeline. At the end of the first season, which was set in the 1901-1909 time period, London Weekend Television ordered a second season. The writers decided to keep the second season in the same time period as the first, interspersing the episodes temporally among those of the first season. However, certain aspects of the plot (Elizabeth's marriage, for instance) were continued as if the events in the first season had taken place immediately before those of the second. When the show was picked up for a third season, it was decided that the show would move forward in time. The final episode of the last season was set in 1930, 28 years after the first episode; while some characters (such as Rose Buck and James Bellamy, both in their 40s at the end of the fifth season) had aged appropriately, others (such as Daisy Peel and Georgina Worsley, both of which were in their mid-20s eighteen years after being introduced at age 18) had not. The timeline became even more convoluted when the series was revived in 2010. While the show was set in 1936, a mere six years after the original had ended, it included some of the characters from the original, whose actors had all aged a few decades in real life.
Desperate Housewives 
Desperate Housewives series creator Marc Cherry opted to begin Season Five at a point five years after the end of the fourth season. The season marked the return of Edie Britt, bringing home her new husband Dave Williams. During the five-year gap, Susan and Mike divorced. Season Five began with Susan about to marry Jackson Braddock. Carlos, having received a blow to the head during the tornado in Season Four, was blind, while his wife Gaby had bore two children and gained a significant amount of weight. Whilst specific dates were not used again in the series, references to contemporary concerns, such as the state of the US economy, were made in some episodes.
Floating timelines are used in animation in much the same way as in comics: characters can retain the same age or general appearance over the years.
Phineas and Ferb 
On Phineas and Ferb the entire length of the three seasons has taken place during one summer vacation (104 days, according to the theme song). After "Phineas and Ferb" released a Christmas special, the show humorously mentions it in the summer's timeline, even though the Christmas special supposedly takes place after summer ends. It was mentioned by the characters that it felt "longer than 104 days" on the 105th episode. This was referenced in one episode called Fly on the Wall where Dr. Doofenshmirtz says that summer keeps going on and on and it feels like it's been going on for four years.
The Simpsons 
On The Simpsons, Bart Simpson has stayed in the fourth grade and Lisa Simpson in the second grade for the show's entire run, and the baby Maggie has never aged. The show has run through the presidencies of George H. W. Bush, Bill Clinton, George W. Bush and Barack Obama. All of them have been addressed as current or former presidents according to the dates when the respective episodes were aired. In "Lisa's Wedding", the story takes place in 2010 – 15 years in the future from the original air date - and Lisa is depicted as being 23. During "Boy Meets Curl", Homer and Marge qualify for the 2010 Vancouver Winter Olympic Games, and Lisa is still in the second grade. Homer is shown as a teenager during the moon landing, yet later shown as a toddler during Woodstock, events only 26 days apart in 1969. New technologies and trends appear, but the basic appearance of the characters never changes. This has been directly referenced by the show; Bart is in love with a girl and wonders why she rejects him, asking Lisa: "Is it the fact that I've worn the same clothes day in, day out, for the last four years?"
There is little continuity in The Simpsons. Major story developments or changes in one episode are not usually further developed in the next, though elements of earlier episode are sometimes subsequently mentioned or shown in the background as part of a joke. There are some instances of the passage of time, such as the aging of Apu Nahasapeemapetilon's octuplets. One fake explanation was made in "Behind the Laughter" (a parody of the VH1 show Behind the Music) where Lisa Simpson stated that she was slipped pills to stunt her growth. The stories are similar to Archie Comics or commedia dell'arte, in which stock characters with identifiable personalities repeatedly appear without much reference to what has gone before. Some major changes, like deaths, have been permanent. Maude Flanders and Bleeding Gums Murphy died and did not reappear except for flashback scenes or Halloween "alternate universe" episodes.
Family Guy 
As the show started in 1999, all characters have aged only a year to two years at most. Chris Griffin was depicted as having attended Buddy Cianci Junior High school at the start of the series; however, six years later, in the 2005 episode Jungle Love, he began attending James Woods High School. His sister Meg has attended James Woods High for the duration of the entire series, another example of the floating timeline concept, however she has aged three years, from sixteen to eighteen. The floating timeline has also been referenced on the show, in the episode Road to Rupert, when Brian tells Stewie that he thinks Stewie's getting a little old to have a teddy bear. Stewie responds with "Brian, I'm one," to which Brian responds with "Still?" The two characters then utter interchanging "What?"s before the story continues without either character mentioning it again. Similarly, Bonnie Swanson appeared to be pregnant through the first seven seasons of the show; Peter points this out in the episode Blind Ambition saying "Bonnie, you've been pregnant for like six years now, either have the baby or don't!" She finally gave birth to Susie Swanson during the 117th episode, Ocean's Three and a Half. One episode from 2011 had Brian and Stewie travel to the pilot episode from 1999 and saw their past selves were all the same age 12 years earlier.
South Park 
Similar effects are observed on the animated TV show South Park, which has depicted Bill Clinton, George W. Bush and Barack Obama as the current U.S. president. While the main characters have aged slightly, moving from third to fourth grade in school, there have been some continuity errors. In the episode "Cartman's Mom is a Dirty Slut", Eric Cartman's father is alleged to be a member of the 1989 Denver Broncos, which would place the characters' conception in 1989, 9 years before the episode's 1998 airing. However, in the 2010 episode "You Have 0 Friends", the Facebook profiles of characters Stan Marsh and Kyle Broflovski list their birth dates as being in 2001.
In both the anime (which began in 1989) and manga, the characters of Ranma Saotome and Akane Tendo are introduced as being 16 years old. Most of the other teenage characters are also 16 years old, while Akane's two sisters Nabiki and Kasumi are 17 and 19 respectively. In Volume 5 of the manga, Ranma is told Satsuki Miyakoji was voted Miss Tea Ceremony for 1993. Much later in Volume 33, Ranma's bill for the damages to the Kunoichi Red Hot Tea House is dated 11/17/2009. However none of the teenage characters have aged.
Similarly, the anime seasons were often updated to reflect the time period in which they were made. In the episode "Clash of the Delivery Girls! The Martial Arts Takeout Race", which first aired on October 20, 1989, the starting line is decorated with banners containing the flags of all the international competitors. The Soviet Union flag is among them. Later in the episode "The Cradle From Hell", which aired on June 12, 1992, the calendar is from 1992 - a full year after the Soviet Union became the Russian Federation. The anime series also had three Christmas specials, yet Ranma and Akane remain 16 years old throughout.
In Pokémon, at the beginning of the original series in 1997, Ash is 10 years old. However, at the beginning of the Best Wishes series in 2010, the narrator states Ash is 10 years old, meaning he hasn't aged at all throughout all four series, even though Ash states upon returning to Pallet Town for the first time in the Indigo League Season that it was a year since he first left.
James Bond 
James Bond is one of the best examples of a floating timeline in film. Bond, as depicted by the films, remains in his early thirties through late 50s consistently since 1962. Bond decreases in age every time the actor changes, with the exception of the transition from Sean Connery (born 1930) to Roger Moore (born 1927). Even some of the supporting characters of the series, such as Felix Leiter and Miss Moneypenny exhibit the same ageless quality thanks to a frequent change in actors. For the remake of Casino Royale, Bond underwent a reboot, discarding the Cold War history of the character for a modern day 21st Century setting and ushering in the latest portrayal of Bond in the film series' history, showing Bond achieving his Double-O licence to kill status, while the same actress continued to portray his superior, M.
Some fan theories attempt to explain Bond's never-aging and his constant changing of appearance (due to new actors taking the role) by stating that James Bond isn't actually the given character's real name, but a code name granted by MI6 to its best or most dashing agent in the field. This would explain how the reboot of the character in Casino Royale managed to incorporate the same actress who played M. In addition, such a theory applies to all characters in James Bond, since they are all secret government agents (including the CIA character, Felix Leiter). The codename theory however has been debunked by other fans, citing little connections made throughout the films to suggest that all the actors (except Daniel Craig) were playing the same character  - as well as showing the tombstone of James Bond's father, who also had the name 'Bond'.
In Tarzan of the Apes, the first of the Edgar Rice Burroughs' famous series, it is noted that Tarzan's parents sailed from Dover on their way to Africa on "a bright May morning in 1888" and that their son was born some months later, soon to be orphaned and raised by apes. But Tarzan's own son grows to manhood in the novel The Son of Tarzan, which was published in 1915. In Tarzan the Untamed, Tarzan plays a role in the First World War, fighting members of the German Imperial Army (and many other foes besides). But in Tarzan and the Foreign Legion - the last which Burroughs wrote - Tarzan is still perfectly fit during World War II, serving as an RAF combat pilot and battling the Japanese after being shot down over Sumatra. In that novel, Tarzan tells how in his youth, after saving the life of a witch doctor, he was rewarded by treatment that gave him immortality. Later (authorised and unauthorised) additions to the series placed Tarzan even later, for example fighting the Mau Mau in the 1950s Kenya.
Nero Wolfe 
Mystery writer Rex Stout created a floating timeline for master detective Nero Wolfe and other principal characters in the corpus, while the stories take place contemporaneously with their writing and depict a changing landscape and society. Nero Wolfe's age is 56. "Those stories have ignored time for thirty-nine years," Stout told his authorized biographer John McAleer. "Any reader who can't or won't do the same should skip them. I didn't age the characters because I didn't want to. That would have made it cumbersome and would seem to have centered attention on the characters rather than the stories."  In the early novels, Wolfe dated himself somewhat by discussing his life before World War I and his combat service in that war, but in later stories he was less explicit about his past.
Nancy Drew 
The Girl detective Nancy Drew began her career in 1930, and still appears in successful novels up to the present. In all that time she became only two years older, sixteen at first and eighteen in the present novels, though the world around her changed considerably (she now uses a mobile phone and drives a hybrid car).
Children's novels 
This phenomenon is even more evident in children's series. In the Sugar Creek Gang books, the series took place between 1940 and 1970, and yet the characters age only two or three years. However, the older books were continually being modernized to fit into the continuity of the series. Similarly, the two sets of Bobbsey Twins endure multiple school years and multiple summer vacations, never aging beyond twelve and six.
Another example of this is in The Babysitters Club books by Anne M. Martin. The books about Kristy, Claudia, Stacey, Mary Anne, Dawn, and Abby who were in 8th grade as well as Jessie and Mallory who were in 6th grade who all belong to a babysitting club started in the mid-1980s and continued until the early 2000s (decade). During this time they did not age at all. They had books dealing with summer vacations, but they always returned to 6th and 8th grade. And as for Enid Blyton's Famous Five, Julian seems to remain about twelve despite fact that he cannot have had so many holidays as 21 (total number of books) from age 12 to 14.
See also 
- see On Continuity: No-Prizes, Retcons, and the Mental Acrobats of Continuity Repair
- Marvel Two-in-One #77
- see 20 and 766
- A report about UNIT in The Sarah Jane Adventures episode "The Lost Boy" refers to UNIT's "golden period that spanned the sixties, the seventies, and some would say, the eighties."
- The Tenth Doctor explains to companion Donna Noble in "The Sontaran Stratagem" that he worked for UNIT "back in the 70s. Or was it the 80s?"
- Doctor Who episode "Aliens of London"
- The Upstairs, Downstairs Web Pages
- "The Red Badge of Gayness" South Park Episode 3.14; November 24, 1999
- "Mystery of the Urinal Deuce" South Park Episode 10.9; October 11, 2006
- "The Snuke" South Park Episode 11.4; March 28, 2007
- "The Coon" South Park Episode 13.2; March 18, 2009
- Burroughs, Edgar Rice. Tarzan and the Foreign Legion, Edgar Rice Burroughs, Inc., 1947. Chapter 25.
- McAleer, John, Rex Stout: A Biography (1977, Little, Brown and Company; ISBN 0-316-55340-9), p. 383; and McAleer, John, Royal Decree (1983, Pontes Press, Ashton, MD), p. 49