Time-traveler UFO hypothesis

The time-traveler hypothesis, also known as chrononaut UFO, future humans, extratempestrial model and Terminator theory is the proposal that unidentified flying objects are humans traveling from the future using advanced technology. Some notable people have given recent public exposure to the hypothesis, such as retired NASA aerospace engineer Larry Lemke, Wisconsin congressman Mike Gallagher, and American filmmaker Steven Spielberg.

The time-traveler hypothesis is considered extremely implausible by mainstream scholars and is generally regarded as unorthodox even among fringe conspiracy theorists who argue that UFOs are extraterrestrial spacecraft or inter-dimensional phenomena.

Origins of time travel speculation
The notion of time travel from the future to the past is thought to have been introduced for the first time in literature by French botanist and geologist Pierre Boitard in his popular 1861 book Paris avant les hommes (Paris before Men), featuring a man sent back to prehistoric Earth where he interacts with an ape-like ancestor, A few years later, in 1887, Camille Flammarion published Lumen, a novel featuring an alien soul traveling through different worlds and historical periods.

Although traveling back in time is almost-universally considered physically impossible, theoretical research has explored whether it might be possible. It has also been speculated by scientists such as J. Richard Gott, Ronald Mallet and others that humans may someday be able to  time travel to the past.

Speculation of future human evolution
Many authors and researchers have speculated about the future evolution of mankind. In 1888 English author H. G. Wells published his famous science-fiction novella The Time Machine featuring a future evolution of humans and is generally regarded as one of the first modern instances of both time travel and speculative evolution. Other writers on speculative evolution include Edgar Rice Burroughs, British philosopher and science fiction writer Olaf Stapledon with his 1930 "future history" novel Last and First Men, American author Kurt Vonnegut in Galápagos, British writer Stephen Baxter in Evolution, Turkish artist and author Cevdet Mehmet Kösemen in All Tomorrows and others. Climate change, the technological singularity, space travel and genetic enhancement have also been identified as potential factors capable of altering the evolution of humans in the future, leading to different transhuman and posthuman scenarios.

UFOs and initial explanations
Human beings have reported unknown objects in the skies since antiquity. In the 1890s, a wave of mystery airships sightings was reported throughout the US, followed by Foo fighters and ghost rockets during World War II.

The modern UFO era began in the Summer of 1947, days after the United States announced plans to re-industrialize Germany over strenuous Soviet objection, sparking the Cold War. Amid fears of a Soviet response, civilian pilot Kenneth Arnold reported witnessing a formation of supersonic aircraft. Wartime prohibition of live "man on the street" broadcasts having ended, Arnold's sighting was covered nationwide on radio and print media. In the days and weeks following the Arnold sighting, a nationwide craze swept the nation as over 800 copycat sightings were published in the English-speaking press. 1947 sources speculated that the sightings resulted from novel US or Soviet technology, misidentification of mundane objects, or behavioral effects like mass hysteria;  Fringe sources suggested that the sightings were a sign of the end of the world, were angelic or demonic, or were vehicles carrying people  from other planets or other "dimensions".

Implausibility of humanoid aliens
Contactee and Alien Abduction folklore often describe encounters with human or humanoid figures and abductors. In his 1964 article The Nonprevalence of Humanoids George Gaylord Simpson claimed that it is extremely unlikely that there exists any form of extraterrestrial intelligence in the Solar System or elsewhere and that, even if they did exist, it was even more unlikely that they would be humanoids. His article was cited and analysed, alongside evolutionary biologist Theodosius Dobzhansky’s similar view on the implausibility of the evolution of humanoid extraterrestrial life forms, in the famous 2014 collection of essays Archaeology, Anthropology and Interstellar Communication edited by astrobiologist Douglas Vakoch and published by NASA in 2014. In the late 1980s, evolutionary biologist and historian of science Stephen Jay Gould put forth his famous thought experiment that if evolution was rewound and played back again it would likely take a very different course and humans would never evolve, which in addition to his declared view against human-oriented evolutionary teleonomy, helped shaped the established view that if intelligent extraterrestrials did exist, they would likely not resemble humans. Biologist Jack Cohen has assumed a similar position about the iconic representation of the Grey alien from reports of UFO abduction and close encounters, stating that extraterrestrials from an alien world could not have evolved a physiology so similar to humans'.

Modern popularization
It is unclear exactly when the hypothesis in its complete form was first proposed. Early versions surfaced between the '70s' pseudoscientific literature and the '90's internet culture, at times associated with the idioms "chrononaut UFOs", "time traveling humans" or simply "future humans". Examples include contributions by Jacques Vallée in his book The Invisible College, Radford University anthropology professor and former Forbes contributor David S. Anderson, Jenny Randles' 2001 book Time Storms, James Herbert Brennan's 1997 book Time-travel: a new perspective, which also draws parallels between the time travelers and elements of the pseudoarchaeological notion of ancient astronauts and Ooparts, and many others. In their 1998 book The Day After Roswell, US Army officer Philip J. Corso and American novelist William J. Birnes reported that German physicist and engineer Dr Hermann Oberth believed the craft recovered at Roswell could have been a time machine.

On April 27, 2012 History aired the "Time Travelers" episode from season 4 of the series Ancient Aliens produced by Prometheus Entertainment, available on Netflix since 2022. In the same year, the "Time Benders" episode from season 18 of the same series aired on History, exploring other aspects of the concept and featuring more speakers, including American professor of biological anthropology Michael P. Masters from the Montana Technological University in Butte, Montana and British journalist and Ministry of Defence civil servant Nick Pope. Pope linked the Rendlesham Forest incident in the UK and the Cabo Valdés Case in Chile with the time-traveler hypothesis, a connection he also explored in his 2014 book (written with John Burroughs, USAF, Ret., and Jim Penniston, USAF, Ret.) Encounter in Rendlesham Forest: The Inside Story of the World's Best-Documented UFO Incident, published by St. Martin's Press. The two episodes feature, among others, ufologists Giorgio A. Tsoukalos, Sean David Morton, authors Erich von Däniken, David Hatcher Childress, Philip Coppens, and theoretical physicist Ronald L. Mallett, discussing the time-traveler hypothesis in the contexts of pseudoarchaeology and pseudohistory.

In 2013, the Huffington Post published an article describing the time-traveler hypothesis and often referencing the Ancient Aliens episode. In the article, the author also reports an online conspiracy theory about how U.S. Navy Commander George W. Hoover allegedly revealed to his son, George Hoover Jr. and later to ufologist William J. Birnes, that the Roswell incident may have involved human beings from the future rather than aliens and that he believed those "beings" were not extraterrestrial, but rather "extratemporal" in nature. The article goes on linking Hoover's story to other alleged UFO sightings and UFO abduction accounts with similar statements and reports about aliens actually being "humans of the future who have found the technology to overcome the limitations of light speed and time travel paradoxes that keep present day humans from breaching the boundaries of time" and that their "often-humanoid appearance may suggest a link between the way we look today, and what we might look like thousands of years from now."

In his 2019 book Identified Flying Objects and subsequent 2022 volume The Extratempestrial Model, Dr Masters explored more in depth various aspects of the time-traveler hypothesis, including fringe ancient astronauts theories and possible future development scenarios of human anatomy such as brain growth, craniofacial evolution, bipedalism, paedomorphism and more. Masters and his theory were featured on various podcasts, such as Sean Patrick Hazlett's Through the Glass Darkly, Kelly Chase's UFO Rabbit Hole, and The Cryptid Factor co-hosted by New Zealand journalist David Farrier, comedian Rhys Darby, producers Dan Schreiber and Leon Kirkbeck.

In 2020 WatchMojo published a video on the topic. In the same year, TNW also published an article about Masters' extratempestrial model. In June 2022, British ESA astronaut Tim Peake mentioned the time-traveler hypothesis in an interview on Good Morning Britain. In a 2023 interview with Stephen Colbert from The Late Show, American filmmaker Steven Spielberg also mentions the theory.

A number of motives for the time-travelers are put forth in the different media where the hypothesis is discussed, such as historical or paleoanthropological interest to study our own past, as well as tourism.

In popular culture
The 1966 Sherwood Schwartz TV series It's About Time portrays 20th-century astronauts being sent back to the stone age after traveling around the earth faster than the speed of light. The astronauts have to contend with the suspicions and superstitions of local cave-dwellers, who regard their advanced technology as sorcery. The astronauts eventually repair their space capsule and return to 1967 with the prehistoric family they befriended.

In Gregory Benford’s 1980 novel Timescape, scientist Saul Shriffer, a colleague of Frank Drake at the SETI Project Ozma, believes that a cryptic signal is of extraterrestrial origin, when it fact it had been sent thirty-four years into the past by humans in the future.

In his 1984 science fiction/fantasy novel Birds of Prey American author David Drake describes six sterile and mutually telepathic sisters who time travel back in time to save humanity from an intelligent but monstrous alien species similar to social insects. The plot suggests that in the future humanity evolves to be quite different from its present form and that the six sisters, along with many other future humans, had become more similar to the insectoid aliens, somewhat of a hybrid between hominids and worker ants or bees, in their attempt to fight them for survival.

In Michael Crichton's 1987 novel Sphere (and subsequent film adaptation of the same name), what was thought to be an alien craft at the bottom of the Pacific Ocean turns out to be a ship built by humans from the future.

In 1993, Syfy (at the time "Sci-Fi Channel") produced their first original TV film, Official Denial, directed by Brian Trenchard-Smith and written by Bryce Zabel, in which a man named Paul Corliss, played by Parker Stevenson, is abducted by aliens who at the end of the movie are revealed to be humans from the future.

In the fifteenth comic book of the Belgian series Blake and Mortimer, The Strange Encounter (2001), British physicist Philip Mortimer and Dr. Walt Kaufman from SUFOS (section of UFO Studies) investigate the corpse Major Lachlan Macquarrie disappeared in the Battle of Saratoga in 1777 after the appearance of three mysterious lights and reappeared in the present under the same circumstances, wearing a baldric inscribed with the words "Yellow King, 8061, Danger, Light, Plutonian, H, Poplar trees, Temple 1954". The same night of the autopsy, Mortimer fights an intruder wearing identical 18th century clothes and anachronistic items to Macquarrie. In the clash, the intruder falls and dies, revealing alien-like features under a human-suit. Based on the mysterious clue found on Major Macquarrie, they hypothesize that the alien could be from Pluto only to instantly realize that his physiology is unsuitable to survive the planet's harsh environment. Later, the dwarf-like alien scientist Dr. Z'ong reveals to Mortimer that commander Basam Damdu, absolute dictator of the Yellow Empire from The Secret of the Swordfish, along with his army, including Zong himself, are humans from 8061, a time when the earth is deserted due to a long nuclear war in the 21st century and humans are an endangered species with alien-like deformities. Some of these plot elements are similar to another earlier episode The Time Trap, where similar events such a post-nuclear dystopian Earth and a rising world order led by a tyrant take place in the 51st century, year 5060.

The English progressive rock band Yes wrote a song titled Aliens (Are Only Us from the Future) entirely dedicated to the subject. The track had been performed during Yes's In the Present world tour, but was never released, until the band's bassist Chris Squire decided to finally published it in 2012 together with English rock band Genesis’s guitarist Steve Hackett and Travis singer Fran Healy as co-writer, calling it simply "Aliens", on their only studio album, A Life Within a Day.

Jordan Peele's 2022 horror movie Nope references "futuristic humans coming back in time to stop us from destroying the planet."

The 2014 movie Interstellar contains deus ex machina beings who built the tesseract environment inside the supermassive black hole Gargantua and possibly placed the wormhole near Saturn that will lead the crew of the Endurance to three potentially habitable exoplanets. These "superior" entities – called bulk-beings by American physicist Kip Thorne in The Science of Interstellar, and referred to by the characters of the movie as "they" – are later revealed by the protagonist Cooper to be humans from the future who evolved to exist in five dimensions, guiding him and his daughter Murph through the necessary steps to crack the equation of quantum gravity and save humanity.

Terminology and connection to other theories
Although in his books and publications Dr Masters uses the neologism "extratempestrial" to describe his model and the alleged beings piloting the UFOs, the overall idea has been dubbed "the time-traveler hypothesis" by executive director of nonprofit Mutual UFO Network (MUFON), Jan Harzan.

The time-traveler hypothesis and the interdimensional hypothesis overlap by a certain degree. People in the ufology community, such as former MUFON director for the state of Pennsylvania John Ventre in an interview with KDKA News Radio, as well as American parapsychologist and engineer Harold E. Puthoff, refer to the two interchangeably. Dr Masters has stated that he considers his extratempestrial model a subcategory of the interdimensional hypothesis. Indeed, from a more scientific standpoint – albeit controversially – within the framework of the many-worlds interpretation of quantum mechanics, temporal paradoxes could be avoided if the time traveler would move from one dimension, or parallel universe, or timeline, to another.

Similarly to how the extraterrestrial hypothesis represents a potential solution to Fermi's paradox, the time-traveler hypothesis provides an alternative explanation for the absence of future time travelers. In an interview with Nova on PBS, astrophysicist and skeptic Carl Sagan stated that there's a possibility that time travelers from the future are already here and we simply don't have the means or the knowledge to recognize them as such, or have other names for them, such as "UFOs or ghosts or hobgoblins or fairies" and that he doesn't think "that the fact that we're not obviously being visited by time travelers shows that time travel is impossible."

Criticism
The time-traveler hypothesis is considered pseudoscientific. American astrophysicist Neil deGrasse Tyson has referred to the hypothesis as illogic. UFO skeptic Robert Sheaffer criticized Masters' work because it relies on "the belief that time travel is not only possible, but real."

British astronomer and science writer David J. Darling has stated that the extraterrestrial hypothesis and the time-travel hypothesis are equally reasonable yet highly unlikely and unnecessary and that, although certain aerial phenomena have indeed eluded identification, there is no apparent reason to justify the claim that they're artificial and/or not of this world. Furthermore, he added that "if some UFOs are 'alien' craft, it's just as reasonable to suppose that they might be time machines from our own future than that they're spacecraft from other stars. The problem is the 'if.' (...) Outside of the popular mythos of flying saucers and archetypal, big-brained aliens, there's precious little credible evidence that they exist. So, my issue with the (Masters') book is not the ingenuity of its thesis, but the fact that there's really no need for such a thesis in the first place."

Referring to the Rendlesham incident, science writer and UFO skeptic Ian Ridpath wrote that time-traveling UFO allegations from retired sergeant Jim Penniston's hypnosis session may have been influenced by him watching the sci-fi film Official Denial (which aired in 1993 and released on video in May 1994, a few months before Penniston's claim surfaced in September of the same year), suggesting a Life imitates art situation, with the film causing Penniston's false memory.

In February 2022, American futurist and science communicator Isaac Arthur discussed the odds against the time-traveler hypothesis on episode 23 Are Aliens Just Time Traveling Humans of the podcast It's Probably (not) Aliens, specifically debunking the concept as it was exposed on the ‘Time Travel’ episode of the Ancient Aliens series.

When asked about the plausibility of UFOs being future humans, Queensland University quantum physicist Fabio Costa told Popular Mechanics: "In a sense, traveling back in time requires two doors, one in the future and one in the past. You can only travel back if someone has opened the door to the past. So, people from the future cannot visit us... unless someone has already invented a time machine and nobody knows! (...) That leaves open the question: where is the time machine?"