21 of the best conspiracy theories

Conspiracy. Just saying the word in conversation can make people politely edge away, looking for someone who won't corner them with wild theories about how Elvis, John F. Kennedy and Bigfoot are cryogenically frozen in an underground bunker.

Conspiracies are sometimes real. The Watergate break-in is a good example of a political conspiracy that actually happened. But thanks to the social-media algorithms that push users toward ever-more-emotional, conspiratorial content, it's probably never been easier for false conspiracy theories to spread.

All conspiracy theories must have certain necessary elements: a conspiracy between two or more people, a secret action, and a motive, said Karen Douglas, a professor of social psychology at the University of Kent in the U.K. But the ones that take off usually have something extra.

"Conspiracy theories are likely to be more successful when they confirm what people want to believe. They are also likely to be successful if they are interesting/exciting and offer a 'big' explanation for a 'big' event," Douglas told Live Science in an email.

Related: Why do people believe in conspiracy theories?

Karen Douglas

Karen Douglas is a Professor of Social Psychology at the University of Kent in the U.K. Her research focuses on the antecedents and consequences of belief in conspiracy theories. She has published widely on these topics and her research regularly features in the media. Karen is currently working on a European Research Council Advanced Grant to study the consequences of conspiracy theories for individuals, groups, and societies.

The top conspiracy theories are often very difficult to dislodge. In part, that's because they fulfill a psychological need, Douglas said. That may be the social need to feel good about the group they belong to, the need to know the truth and have certainty, or the existential need to feel safe or feel a sense of control over what happens to us.

And hardcore believers are adept at rationalizing away evidence that contradicts their beliefs. Eyewitnesses who dispute the conclusions of even the biggest conspiracy theories are mistaken, according to believers — or part of the conspiracy.

The truth, however, is out there …

The dead internet conspiracy theory

The dead internet theory first surfaced on the Agora Road's Macintosh Cafe forum in 2021, when a user started a thread called "Dead Internet Theory: Most Of The Internet Is Fake." Citing posts from major online discussion forums like 4Chan, the theory claimed that non-human bots are responsible for almost all online activity and content creation.

At a top level, the concept is that artificial intelligence (AI) and chatbots automatically churn out social media posts designed to farm clicks, comments and likes on platforms like Facebook and TikTok. They do this because more engagement leads to more advertising dollars.

But the accounts responding to those automatic posts are in turn bots and AI agents, the conspiracy claims. In other words, everything is happening between machines, no humans needed. Go deeper down the rabbit hole, and some dead internet proponents argue that government organizations use these bots to manipulate human opinions.

Proponents argue the internet died around 2016 or 2017 — we just didn't know it back then.

This conspiracy theory has a little kernel of truth at its core: bots account for around half of all internet traffic, research suggests. That said, there are definitely humans on the internet.

The 9/11 Conspiracies

The evidence is overwhelming that the terrorist attacks of Sept. 11, 2001, were indeed the result of a conspiracy: a conspiracy of Osama bin Laden and a crew of mostly Saudi hijackers.

This is too simple for some, though. Conspiracy theorists have a variety of much more complex explanations for what happened at the World Trade Center and Pentagon that day, often involving insider knowledge by President George Bush, Vice President Dick Cheney and top Bush advisors.

Some famous conspiracy theories rely on anti-Semitic tropes, such as the attacks being orchestrated by Israel. Many claim that because "jet fuel can't melt steel beams," the Twin Towers must have been brought down by controlled demolition from bombs planted before the planes hit. (A 2006 NOVA documentary debunked these claims. It is, in fact, quite possible for the columns holding up skyscrapers to fail catastrophically when exposed to fires burning on multiple floors.)

Other claims are refuted by simple logic: If a hijacked airplane did not crash into the Pentagon, as is often claimed, then where is Flight 77 and its passengers? In many conspiracy theories, bureaucratic incompetence is often mistaken for conspiracy. Our government is so efficient, knowledgeable and capable — so the reasoning goes — that it could not possibly have botched the job so badly in detecting the plot ahead of time or responding to the attacks.

Princess Diana's murder

Within hours of Princess Diana's death on Aug. 31, 1997, in a Paris highway tunnel, conspiracy theories swirled. As was the case with the death of John F. Kennedy, the idea that such a beloved and high-profile figure could be killed so suddenly was a shock. This was especially true of Princess Diana: Royalty die of old age, political intrigue or eating too much rich food; they don't get killed by a common drunk driver.

Unlike many conspiracy theories, though, this one had a billionaire promoting it: Mohamed Al-Fayed, the father of Dodi Al-Fayed, who was killed along with Diana. Al-Fayed claims that the accident was in fact an assassination by British intelligence agencies, at the request of the Royal Family. Al-Fayed's claims were examined and dismissed as baseless by a 2006 inquiry; the following year, at Diana's inquest, the coroner stated that "The conspiracy theory advanced by Mohamed Al Fayed has been minutely examined and shown to be without any substance." On April 7, 2008, the coroner's jury concluded that Diana and Al-Fayed were unlawfully killed due to negligence by their drunken chauffeur and pursuing paparazzi, The New York Times reported.

The conspiracy theory was also believed by Prince Harry, who said in January, 2023, that he believed she could still be alive for "many years" after the crash. He told Anderson Cooper on "60 Minutes" that he thought she may have faked her own death and they would be reunited at some point.

Subliminal advertising

Ever been watching a movie and suddenly get the munchies? Or sitting on your sofa watching TV and suddenly get the irresistible urge to buy a new car? If so, you may be the victim of a subliminal advertising conspiracy! Proponents of this conspiracy theory include Wilson Bryan Key (author of "Subliminal Seduction") and Vance Packard (author of "The Hidden Persuaders"), both of whom claimed that subliminal (subconscious) messages in advertising were rampant and damaging. Though the books caused a public outcry and led to FCC hearings, much of both books have since been discredited, and several key "studies" of the effects of subliminal advertising were revealed to have been faked.

In the 1980s, concern over subliminal messages spread to bands such as Styx and Judas Priest, with the latter band even being sued in 1990 for allegedly causing a teen's suicide with subliminal messages (the case was dismissed). Subliminal mental processing does exist, and can be tested. But just because a person perceives something (a message or advertisement, for example) subconsciously means very little by itself. There is no inherent benefit of subliminal advertising over regular advertising, any more than there would be in seeing a flash of a commercial instead of the full twenty seconds. Getting a person to see something for a split-second is easy; filmmakers do it all the time (watch the last few frames in Hitchcock's classic "Psycho"). Getting a person to buy or do something based on that split-second is another matter entirely.

Moon landing hoax

NASA landed astronauts on the moon in 1969. By the 1970s, a bizarre conspiracy emerged — that the moon landing never happened.

The conspiracy was described in a 1976 self-published book, "We Never Went to the Moon: America's Thirty Billion Dollar Swindle," and a 1978 movie, "Capricorn One." Even as late as 2001, there was a Fox documentary, "Conspiracy Theory: Did We Land on the Moon?" that gave air time to the claims that the whole Apollo moon-landing program was faked.

There are plenty of debunkings of the various moon hoax claims, and then there's the issue of the hundreds of pounds of moon rocks that have been studied around the world and verified as being of extraterrestrial origin. How did NASA get the rocks if not during a moon landing? Why would scientists from around the globe willingly participate in the American space agency's hoax?

Many astronauts have been offended by the implication that they faked their accomplishments. In 2002, when conspiracy theorist Bart Sibrel confronted Buzz Aldrin and called him a "coward and a liar" for faking the moon landings, the then 72-year-old punched Sibrel in the jaw.

Paul McCartney's death

Paul McCartney is not dead. As of mid-2024, he was still touring. He gives interviews, he has a website, he occasionally appears in the tabloids.

Pretty good for a guy that some conspiracy theorists think died in 1966.

The "Paul is dead" conspiracy goes something like this: On Nov. 9, 1966, Paul McCartney got into an argument with the other Beatles, stormed out of the studio and was promptly decapitated in a car accident. To cover the whole thing up, the band hired a look-alike (and sound-alike).

After going through all this trouble, though, the band then took great pains to drop clues in their album covers and lyrics to hint to the public that something was amiss. For example, on the cover of the Abbey Road album, all four Beatles are photographed striding across a zebra crossing, but only McCartney is barefoot and out of step with the other three. This must mean something, right? Despite public denials by the band (and many, many public appearances by McCartney), fans couldn't just let it be, and came together to look for more clues.

John F. Kennedy's assassination

John F. Kennedy was shot in 1963 in a Dallas motorcade. But did Lee Harvey Oswald act alone? Or was there a second gunman on the grassy knoll?

These questions are the gateway to a vast arena of conspiracy theories that have spawned endless speculation and hundreds of books, articles and films. It didn't help that Lee Harvey Oswald was murdered in the basement of Dallas Police Headquarters while surrounded by police officers only two days after the assassination — and by a guy with ties to the Mob. The whole thing stunk, people figured.

Plenty of shadowy culprits have been suggested as the masterminds of the Kennedy assassination: Fidel Castro's government, or maybe anti-Castro activists, or organized crime, or the CIA, or Vice President Lyndon Johnson, or … Well, the thing about presidents is, it turns out, they have a lot of enemies. The Warren Commission report, produced by the official investigation into Kennedy's death, found no evidence of overarching conspiracies, though plenty of theories still flourish.

Roswell crash & cover-up

There is one fact that almost all skeptics and believers agree on: Something crashed on a remote ranch outside of Roswell, New Mexico in 1947. The government at first claimed it was some sort of saucer, then retracted the statement and claimed it was really a weather balloon. Yet the best evidence suggests that it was neither a flying saucer nor a weather balloon, but instead a high-altitude, top-secret military balloon dubbed Project Mogul.

As it turns out, descriptions of the wreckage first reported by the original eyewitnesses very closely match photos of the Project Mogul balloons, down to the silvery finish and strange symbols on its side. The stories about crashed alien bodies did not surface until decades later and in fact no one considered the Roswell crash as anything extraterrestrial or unusual until thirty years later, when a book on the topic was published. There was indeed a cover-up, but it did not hide a crashed saucer. Instead, it hid a Cold War-era spying program.

Protocols of the Elders of Zion

"The Protocols of the Learned Elders of Zion" is a hoaxed antisemitic book that purported to reveal a Jewish conspiracy to achieve world domination. It first appeared in Russia in 1905, and described how Christians' morality, finances, and health would be targeted by a small group of powerful Jews. The antisemitic idea that there is a Jewish conspiracy is nothing new, of course, and has been repeated by many prominent people including Henry Ford and Mel Gibson. In 1920, Henry Ford paid to have half a million copies of "The Protocols of the Elders of Zion" published, and in the 1930s, the book was used by the Nazis as justification for its genocide against Jews (in fact, Adolf Hitler referred to the "Protocols" in his book "Mein Kampf").

Though the book has been completely discredited as a hoax and forgery, it is still in print and remains widely circulated around the world.

The Satanic panic

For years during the 1980s and 1990s, America became convinced that an underground network of Satanists was working together to kidnap, torture and abuse children. None of it was real, but the conspiracy theories destroyed lives and livelihoods.

The pinnacle was Geraldo Rivera's infamous NBC special "Devil Worship: Exposing Satan's Underground," which aired on Oct. 28, 1988. Rivera relied on self-proclaimed "Satanism experts," misleading and inaccurate statistics, crimes with only tenuous links to Satanism, and sensationalized media reports. It was the most-viewed documentary in television history. "There are over one million Satanists in this country," Rivera said, adding that "The odds are, [they] are in your town."

The panic grew out of the idea that memories of abuse were often repressed and could be recovered with the help of hypnosis and a therapist. This idea was popularized in the 1980 book "Michelle Remembers," co-written by a Canadian psychiatrist and the patient he eventually married (ethics red flag), in which the eponymous Michelle recovers memories of supposed ritual Satanic abuse conducted by her mother.

In 1983, the panic exploded with the McMartin preschool trial, in which a California parent accused daycare owners of sexually abusing her son. Police then sent a letter to parents warning that their children may have been abused, urging the parents to ask what turned out to be leading questions to a bunch of suggestible preschoolers. Further questioning by authorities continued in this vein, yielding alleged eyewitness accounts by children of networks of secret tunnels and witches flying through the air.

After seven years, the daycare owners were eventually acquitted or had the charges dismissed. One was jailed for five years while awaiting trials and retrials. In the meantime, similar accusations spread through daycares around the country. Most were spurred on by now-discredited methods of questioning small children, methods that often led to children making sensational accusations because they wanted to please the authority figures questioning them.

In a 1992 report on ritual crime, FBI agent Kenneth Lanning concluded that the rampant rumors around ritual Satanism were unfounded. Phillips Stevens, Jr., associate professor of anthropology at the State University of New York at Buffalo, said that the widespread allegations of crimes by Satanists "constitute the greatest hoax perpetrated upon the American people in the twentieth century."

Chemtrails

As airplanes travel, they leave behind them long water condensation trails called contrails. These cloud-like tracks dissipate quickly.

But to some conspiracy theorists, these condensation trails are much more nefarious. The "Chemtrails" conspiracy theory holds that condensation trails are full of other chemicals that scientists and governments are seeding into the atmosphere. Why? Pick your reason. It might be biological warfare or population control or geoengineering or an attempt to manipulate the weather.

Researchers who study things like clouds' impact on global temperatures are often harassed by Chemtrails believers, who think they're part of a large-scale conspiracy to secretly spray unknown chemicals into the atmosphere, according to Harvard University's David Keith. A 2016 study even debunked chemtrails scientifically, finding no evidence of unusual contrails or unexplained contamination in the environment. But true believers aren't swayed, as The Guardian reported in 2017.

Barack Obama birtherism

Some conspiracies, like chemtrails, percolate in the background of certain communities, never really penetrating the larger public. Others have big impacts. The Barack Obama birtherism conspiracy is one of the latter.

Barack Obama, the 44th president of the United States, was born in 1961 in Honolulu, Hawaii. But as soon as Obama began his campaign for president in 2008, "birthers" began to circulate the conspiracy theory that Obama had actually been born in Kenya, the country of his father. They argued that this meant Obama was not "a natural-born citizen of the U.S." — even though his mother was an American citizen — and thus he could not be president.

Nevermind that there were announcements of Obama's birth in the Honolulu newspaper, or that friends of Obama's mother remembered the day she went into labor. To combat the conspiracies, Obama not only had to release a copy of his birth certificate in 2008, he had to follow up with a release of the original "long form" document in 2011, contrary to the hospital's usual policy of issuing computer copies of birth certificates as acceptable identification.

The 2011 release reduced the number of Americans who believed in birtherism, according to Gallup polling. But many conservative political activists and pundits raised their profiles by advocating for birtherism. Among them? Donald Trump, who was at the time the soon-to-be-president.

COVID and 5G

Probably no event since 9/11 has spawned more conspiratorial thinking than the COVID-19 pandemic. There are conspiracies about the origin of the virus as well as basically every government's reactions. Many people even believe doctors are lying about COVID-related deaths, blaming the virus for deaths with other causes. A distrust of "Big Pharma," fomented for years by "alternative medicine" advocates like Kevin Trudeau (bestselling author of "Natural Cures They Don't Want You To Know About" — a textbook conspiratorial title if there ever was one), have also fed into conspiracies about medical treatment and vaccination.

One of the odder conspiracies mixes long-standing fears of 5G wireless technology with fears about the virus. According to the COVID 5G conspiracy, electromagnetic frequencies from cell phone towers undermine the immune system, making people sick with COVID, researchers reported in 2020 in the journal Media International Australia. Another conspiracy theory claims that the COVID-19 vaccines contain tracking chips that connect to 5G networks so that the government, or possibly billionaire and vaccine philanthropist Bill Gates, can surveille everyone's movements.

As CNBC points out, 5G chips are too large to fit through a vaccine syringe, and even the smallest RFID chips that could fit require a power source that couldn't make the squeeze.

Birds aren't real

When is a conspiracy not a conspiracy? When it's an elaborate piece of performance art.

Or… does that make it even more of a conspiracy theory?

The Birds Aren't Real conspiracy is a movement developed by Peter McIndoe, 23, who started spreading the idea in 2017. Until a December 2021 interview in the New York Times, McIndoe stayed in-character as a true believer, insisting in media interviews and online that birds aren't real, but rather they are surveillance drones made by the U.S. government. Birds Aren't Real has a staff; it has organized real-life protests; it bought real-life billboards; and it emblazoned vans with their claim. The goal, says McIndoe, is to parody the misinformation that Gen Z finds itself stewing in.

"Birds Aren't Real is not a shallow satire of conspiracies from the outside. It is from the deep inside," he told The New York Times. "A lot of people in our generation feel the lunacy in all this, and Birds Aren't Real has been a way for people to process that."

The experiment revealed that conspiracies sometimes grow by credulity: Local media sometimes reported on Birds Aren't Real as if it was something young people really believed rather than an elaborate joke. Birds Aren't Real organizers hope the joke will become a force for good by exposing all the ways misinformation thrives.

"Yes, we have been intentionally spreading misinformation for the past four years, but it's with a purpose," McIndoe said. "It's about holding up a mirror to America in the internet age."

The Earth is flat

Flat-Earth conspiracy theories first arose in the 1950s and have been given new life in the Internet age. They’re bizarre, almost quaint. After all, even ancient people knew the Earth was round. The Greeks even figured out the planet’s circumference in the 3rd century. Since then, astronauts have launched into space and seen the “Blue Marble” with their own eyes.

But Flat Earth believers don’t see beyond their own horizon: The line between Earth and sky looks pretty flat, they figure, and all the rest of the evidence gets tossed out the window. On YouTube and message boards, Flat-Earthers spend their time inventing weird physics to try to explain how things like gravity and lunar eclipses could possibly work if Earth were a flat disk. Many are motivated by religious belief or the desire to see the universe as a more caring, human-centered place, Michael Wood, a lecturer in psychology at the University in Winchester in England, told Live Science in 2018.

COVID treatments cause COVID deaths

The “COVID vaccines contain 5G chips” conspiracy theory is easy to mock, but a less-absurd-sounding conspiracy around COVID is very likely costing lives: Some people believe that the very drugs that can be used to treat COVID-19 are actually killing patients.

This has led to stories about people infected with the disease who have refused effective drugs, like the antiviral remdesivir, because they’ve put their trust in online “alternative health” sources who are often selling their own unproven (or in many cases, disproven) treatments. One of these viral alt-health podcasters, a former chiropractor named Bryan Ardis, has also been spreading the bizarre notion that COVID-19 isn’t even caused by a virus, but by snake venom injected into “certain people” by the Catholic Church and the U.S. Centers for Disease Control and Prevention. No word on how the millions of people infected with COVID-19 at this point have failed to notice the Pope skulking around their bedroom with a syringe full of snake venom, but never mind. Ardis, of course, sells his own line of supplements meant to combat this imaginary venom.

Reptilians run the U.S. government

The idea that the U.S. government (or perhaps the entire world government) is run by reptilian humanoids is … out there, to say the least. And yet, people holding this belief have done real damage. For example, a man who detonated a bomb in downtown Nashville, Tennessee, on Christmas Day 2020 had written a friend about his belief that lizard people walked the planet, disguised as humans. Warner killed himself, damaged 41 buildings, and injured three in the bombing.

The idea of half-lizard, half-human beings goes way back, with one academic tracing it to a pulp fiction magazine story from 1929. British conspiracy theorist David Icke has been a key spreader of the “reptilian shapeshifters control the world” conspiracy, which sometimes overlaps with New World Order conspiracy theories that suggest that an elite cabal plan to institute authoritarian global government. These conspiracies often overlap with anti-Semitism, assigning this supposed cabal Jewish roots.

The reptilian conspiracy theory got a small signal-boost with the death of Queen Elizabeth II in September 2022. According to Politifact, Facebook flagged and removed multiple posts after the queen’s death calling the monarch a reptile and linking to strange videos claiming the entire royal family is reptilian.

Health authorities are hiding natural cures

Conspiratorial thinking about health is widespread. A 2014 research letter published in JAMA Internal Medicine found that 37% of Americans believe that the Food and Drug Administration is suppressing natural cures for cancer because of drug company pressure. This was the most-believed health conspiracy in the study. Twenty percent also said they believed public health officials to be hiding data showing that cell phones cause cancer, and 20% said that doctors vaccinate children with risky immunizations, knowing them to be dangerous.

The National Cancer Institute reports that there has been no link found between cell phone use and cancer, and the 1998 study that first linked vaccines with autism was retracted by the journal for research misconduct. And as for natural cures for cancer? Respected oncologists actually do support treatment such as massage and music therapy for cancer patients — but alongside pharmaceuticals that are tested in clinical trials and have a proven track record.

Many "natural health" promoters get rich selling their own (unregulated) supplements and vitamins, making their financial conflict of interest just as pressing as any pharmaceutical company's. Kevin Trudeau, author of the book "Natural Cures 'They' Don't Want You to Know About" and "Diet Cures 'They Don't Want You to Know About," was convicted of fraud in 2013 for making false claims in his infomercials and books. Despite spending eight years in prison, he's still giving talks and raising money from his fan club — money the federal government is currently trying to trace, as Trudeau owes nearly $37 million as a settlement for the people who bought his falsehood-filled diet book.

Fan theories gone wild

Not all conspiracy theories are political — or even that consequential. The world of internet fandoms can be wild, with true believers on social media spinning dramatic tales about their favorite celebrities' real lives.

The weirdest of these theories play on the fact that fans know the celebrities they see on their screens are packaged through production companies and filtered through public relations strategies. This sheen of unreality may make it easier to believe, for example, that Canadian singer Avril Lavinge is dead and has been since around 2003, when her record company replaced her with a body double.

"It's so dumb," Lavinge (who is very much alive) told EW in 2019.

An even bigger brouhaha arose around Chinese actor Zhang Zhehan, who was canceled and denounced in 2021 after pictures emerged of him online visiting a controversial Japanese World War II memorial. Zhang's career evaporated overnight, and when he returned to social media after months away, some fans became convinced that this new poster was a deepfake, according to Vox. They even analyzed the facial wrinkles of his pet dog and doxxed the actor's therapist. (Zhang now has a verified Instagram account and is experiencing a career revival outside of China.)

Celebrities have reported these conspiracies affect their real lives. A group of One Direction fans called "Larries" spent years insisting that now-former bandmates Harry Styles and Louis Tomlinson were a secret couple, which affected the pair's real friendship, Tomlinson told Seventeen magazine in 2017. "It created this atmosphere between the two of us where everyone was looking into everything we did," Tomlinson said. "It took away the vibe you get off anyone."

"They" want you to eat bugs

To combat climate change, experts recommend eating less meat and more plants. In some circles, this advice for a warming planet has transformed into something more sinister: The "ruling class" wants everyone (else) to eat bugs.

It's a claim made by conservative media personalities like Michael Knowles and Tucker Carlson, and often used to mock anyone who suggests the need to reduce greenhouse gas emissions. According to NPR, the conspiracy theory percolated through the message board 4chan starting in 2019. Some social media posters talk about the theory with a sardonic flare — the phrase "I will not eat the bugs," is a common refrain — while others have attempted to tie it in with wider anti-Semitic beliefs about a global cabal trying to control the masses.

The darkest version of these conspiratorial beliefs is called "The Great Reset," which holds that the global elite plan to enslave the masses in a kind of survivalist dystopia, where freedom is a thing of the past and the only thing to eat is insects.

Denver International Airport is a hub for the Illuminati

The Denver International Airport is a quirky place, known for its offbeat art: Gargoyles overlook the baggage claims, murals depict scenes of war and horror, and there's a 32-foot (9.75 meter) blue horse with red eyes presiding over the road leading in and out of the terminal.

All of this weirdness, combined with the municipal drama surrounding the airport's construction (the project went almost $3 billion over budget), sparked an array of conspiracy theories. The most common, according to the Denver Public Library, is that the airport is secretly the headquarters of the New World Order, the Illuminati, the Reptilians or some other shadowy groups with plans to take over the world.

To bolster these beliefs, theorists spin alternative explanations of the airport's odd decor. For example, an inlay in the floor with the symbols for "gold" (Au) and "silver," (Ag) referencing Colorado's mining history, become a secret message about a made-up pathogen known as the Australian Antigen. A mural decrying war and wishing for world peace becomes a warning about a totalitarian future.

All of this is built, according to the theorists, on top of a six-story deep bunker where the elites will hunker down to ride out the end of the world. Or maybe it's a prison for dissenters. Of course, there's no evidence of anything beneath the airport besides maintenance tunnels, a baggage transport system, and harried travelers moving between terminals on an underground train. But that doesn't stop those who want to believe in something more nefarious beneath this airline hub.

Conspiracy theories may be popular, but they are far from harmless.

"Conspiracy theories historically have been linked with prejudice, genocide, risky health behaviour, climate denial, and more recently some quite disturbing behaviour related to QAnon and COVID-19 conspiracy theories. They can turn people away from mainstream politics and science," Douglas said.

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