19 of the Strangest Unsolved Mysteries of All Time

Get ready to have the hair on the back of your neck stand on end. These unsolved mysteries are among the most chilling we’ve ever heard.

1 / 19
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The incident at Dyatlov Pass

On the first night of February 1959, nine ski-hikers died mysteriously in the mountains of what is now Russia. The night of the incident, the group had set up camp on a slope, enjoyed dinner, and prepared for sleep—but something went catastrophically wrong because the group never returned.

On February 26, searchers found the hikers' abandoned tent, which had been ripped open from the inside. Surrounding the area were footprints left by the group, some wearing socks, some wearing a single shoe, some barefoot, all of which continued to the edge of a nearby wood. That's where the first two bodies were found, shoeless and wearing only underwear. The scene bore marks of death by hypothermia, but as medical examiners inventoried the bodies, as well as the other seven that were discovered over the months that followed, hypothermia no longer made sense. In fact, the evidence made no sense at all. One body had evidence of a blunt force trauma consistent with a brutal assault; another had third-degree burns; one had been vomiting blood; one was missing a tongue, and some of their clothing was found to be radioactive.

Theories floated include KGB-interference, drug overdose, UFO, gravity anomalies, and the Russian version of the Yeti. Recently, a documentary filmmaker presented a theory involving a terrifying but real phenomenon called "infrasound," in which the wind interacts with the topography to create a barely audible hum that can nevertheless induce powerful feelings of nausea, panic, dread, chills, nervousness, raised heartbeat rate, and breathing difficulties. The only consensus remains that whatever happened involved an overwhelming and possibly "inhuman force."

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2 / 19
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Sickening noises

In December 2016, a CIA officer checked in to the American Embassy’s health office in Havana suffering from nausea, headache, and dizziness. Days later, two more CIA officers reported similar ailments. By late 2018, the number grew to 26 Americans and 13 Canadians experiencing nausea, hearing loss, vertigo, nosebleeds, and focusing issues. In all the cases, victims claimed that the symptoms were triggered by a strange noise they’d heard at their homes or hotel rooms. One person said the noise was high-pitched. Another described “a beam of sound, pointed into their rooms.” Some insisted that the noise more closely resembled marbles rolling along the floor.

The illnesses confounded medical experts. Doctors at the University of Pennsylvania who examined some of the victims diagnosed concussion-like symptoms but found no signs they’d suffered concussions.

We know what you must be thinking: The Cuban government is up to something, right? The Cubans vehemently deny they’re responsible, and many American investigators believe them. That’s because they still don’t know who or what made the victims sick. Was it a new type of weapon? The CIA claims it doesn’t know of any weaponry that could cause these symptoms. What about ultrasound? One theory holds that a pair of covert eavesdropping devices placed too close to each other by Cuban agents may have inadvertently produced such a reaction, like the kind of feedback you hear when someone stands too close to a microphone. But the FBI has found no evidence to substantiate that argument. In fact, ultrasound is above the range of human hearing.

Recordings of the sounds from some of the victims only added to the confusion. Two scientists who studied the recordings believe they captured the sound of lovelorn male crickets. One of the scientists, Alex­ander Stubbs of the University of California, Berkeley, says the insects are incredibly loud. “You can hear them from inside a diesel truck going 40 miles an hour on the highway.” Still, the scientists had no idea why the sounds might lead to illness in humans.

Maybe it was just nerves. “Cuba is a high-threat, high-stress post,” a former embassy official told propublica.org. Diplomats are warned that “there will be surveillance. There will be listening devices in your house, probably in your car. For some people, that puts them in a high-stress mentality, in a threat-anticipation mode.”

True—but then how to explain what happened in China? In May 2018, an American posted in the consulate in Guangzhou was diagnosed with the very same mystery illness. Ultimately, 15 Americans were evacuated.

While the seemingly airborne cause of these brain injuries is still a mystery, the fallout is clear. The Americans removed 60 per cent of their diplomats from Cuba and expelled 15 Cuban diplomats from Washington, DC. The mysterious sounds may well be the opening shots in a new kind of cold war.

These are the secrets the CIA doesn't want you to know.

3 / 19
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Ghost ship

On December 4, 1872, a British-American ship called "the Mary Celeste" was found empty and adrift in the Atlantic. It was found to be seaworthy and with its cargo fully intact, except for a lifeboat, which it appeared had been boarded in an orderly fashion. But why? We may never know because no one on board was ever heard from again.

In November 1872, the Mary Celeste set sail from New York bound for Genoa, Italy. She was manned by Captain Benjamin Briggs and seven crew members, including Briggs' wife and their 2-year-old daughter. Supplies on board were ample enough for six months, and luxurious—including a sewing machine and an upright piano. Commentators generally agree that to precipitate the abandonment of a seaworthy ship, some extraordinary and alarming circumstance must have arisen. However, the last entry on the ship's daily log reveals nothing unusual, and inside the ship, all appeared to be in order.

Theories over the years have included mutiny, pirate attack, and an assault by giant octopus or sea monster. In recent years, scientists have posed the theory that fumes from alcohol on board caused an explosion that, as a result of scientific anomaly, did not leave behind signs of burning—but was terrifying enough that Briggs ordered everyone into the lifeboat.

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4 / 19
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Who (and where) is DB Cooper?

On November 24, 1971, Dan Cooper was a passenger on Northwest Airlines Flight 305, from Portland to Seattle—a 30-minute flight. He was described by passengers and flight attendants as a man in his mid-40s, wearing a dark suit, black tie with a mother-of-pearl tie-clip, and a neatly-pressed white collared shirt. He took his seat, lit a cigarette, and politely ordered a bourbon and soda, for which he paid cash. Shortly after takeoff, he handed a note to a 23-year old flight attendant, who ignored it, assuming it was just the man's phone number.

"Miss, you'd better look at that note," Dan Cooper told her, "I have a bomb."

The note's exact wording is part of the mystery, since Cooper reclaimed it after the flight attendant read it, but his demands were for $200,000 in "negotiable American currency" (worth $1 million dollars today), four parachutes, and a fuel truck standing by in Seattle to refuel the plane on arrival. The flight attendant brought the demands to the captain. The airline's president authorized full cooperation. The other passengers had no idea what was happening, having been told that landing was delayed due to mechanical difficulties.

At 5:39 p.m., the plane landed, an airline employee delivered a cash-filled knapsack and parachutes, and Cooper allowed all passengers and two flight attendants to leave the plane. During refueling, Cooper outlined his plan to the crew: a southeasterly course toward Mexico with one further refueling stop in Nevada. Two hours later, the plane took off. When it landed in Reno, Cooper's absence was noted. Cooper (whom the media mistakenly referred to as "DB Cooper") was never seen or heard from again. No parachute was found, and the ransom money was never used.

In 1980, a young boy on vacation with his family in Oregon found several packets of the ransom money (identifiable by serial number), leading to an intense search of the area for Cooper or his remains. Nothing was ever found. For a time, it was speculated that Mad Men's (fictional) Don Draper was the man who would become Cooper. In the real world, a parachute strap was recently found at one of Cooper's possible landing sites. Stay tuned.

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5 / 19
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Living statues

From 1917 to 1928, half a million people were afflicted with a ghastly condition that could be part of the plot line of a horror film. The victims—very much alive and conscious—found themselves in inexplicably frozen states, their static bodies prisons for their minds.

Encephalitis lethargica (EL), aka “the sleeping sickness,” first appeared in Europe and quickly spread around the world, reaching epidemic levels in North America, Europe, and India by 1919. About a third of those stricken with the illness died. Of the survivors, nearly half eventually found themselves unable to physically interact with the world around them, all the while fully aware of their surroundings. Though occasionally capable of limited speech, eye motion, and even laughter, they generally appeared as living statues—totally motionless for hours, days, weeks, or years.

The cause is unknown, but one theory is brain inflammation triggered by a rare strain of streptococcus, the bacteria responsible for many sore throats each year. Science’s best guess is that the bacteria mutated, provoking the immune system to attack the brain, leaving the victim helpless.

None of this explains why the illness disappeared only to resurface sporadically, be it in Europe in the 1950s or in China ten years ago when a 12-year-old girl was hospitalized for five weeks with the disease.

Are such occurrences the new normal, or are they signs that EL could be planning something bigger any day? A 2004 analysis of 20 patients with symptoms remarkably similar to EL concluded that whatever ailed them “is still prevalent.” As such, history’s so-called sleeping sickness remains the stuff of nightmares.

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6 / 19
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What is Area 51?

Area 51, in southern Nevada, is a U.S. military base, the very existence of which was unconfirmed until 2013, when the CIA was obliged to respond to a Freedom of Information Act request from 2005. Based on historical evidence, it would appear that Area 51 supports the development and testing of experimental aircraft and weapons. Public satellite images, such as those available on Google Maps, don't provide insight. Even those with security clearance to visit Area 51 are transported there from Las Vegas via an airline called "Janet," whose planes are unmarked and which shrouds its windows upon descent.

The intense secrecy surrounding Area 51 has sparked rumours that the government uses it to house crashed UFOs and conduct lab tests on aliens. Other theories about what Area 51 is used for include: research on time travel, research on teleportation, meetings with extraterrestrials, development of a means for weather control, and activities related to a shadowy one-world government. Where these theories come from is as much a mystery as Area 51, itself, but one thing is certain: people love a good conspiracy theory. At one point, conspiracy theorists believed the moon landing in 1969 had been faked. Hint: it wasn't.

Delve into the most chilling UFO sightings ever recorded.

7 / 19
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Roaming ruins

It’s not unusual to find junk in Brazil’s Guanabara Bay, but what Robert Marx unearthed there in 1982 was an unusual kind of foreign matter. In an underwater field the size of three tennis courts located 15 miles from shore lay the remains of some 200 Roman ceramic jars, a few fully intact. According to Marx, a professional treasure hunter, the jars appeared to be twin-handled amphorae that were used to transport goods such as grains and wine in the third century. But how did they get there? The first Euro­peans didn’t reach Brazil until 1500.

The Romans, who traded primarily in Mediterranean port cities and the Middle East, had little incentive to invest in ships that could cross oceans. However, they did sail as far as India. Perhaps some untrained navigator lost his way in a storm. Or maybe mutineers steered the ship westward?

We may never know, nor are we likely to uncover more evidence. Brazil closed the Bay of Jars to further research in 1983 in an effort to deter looters, it said. Marx claims the government didn’t want the area explored because finding Roman-era artifacts there would mean that, contrary to Brazil’s official history, the Portuguese were not the first Euro­peans to reach the country. And 
the truth? It’s resting 100 feet under the sea.

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8 / 19
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What is the Voynich Manuscript?

The Voynich Manuscript is a roughly 250-page book written in an entirely unknown language/writing system. It's been carbon-dated back to the 1400s and includes illustrations of plants that don't resemble any known species. It's named for the Polish book dealer who purchased it in 1912. It is believed to have been intended as a medical text. Its first confirmed owner was Georg Baresch (1585–1662), an alchemist from Prague, who discovered it "taking up space uselessly in his library." Baresch tried to investigate the manuscript's origins, to no avail.

The manuscript changed hands for centuries until it was purchased by Voynich, who posited that it was authored by Albertus Magnus (an alchemist) or Roger Bacon (an early scientist). However, some believe that Voynich fabricated the manuscript and its history all by himself. Various other hoaxes have been proposed over the years. Of course, that wouldn't explain the carbon-dating of the paper and ink.

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9 / 19
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Do the Pollock Sisters prove reincarnation?

Although scientists tend to poo-poo the possibility of reincarnation, every once in a while, a story comes around that is so compelling and otherwise unexplainable that it gives even scientists pause. That is what we have in the story of the Pollack sisters.

In 1957, two young English sisters, Joanna Pollock, 11, and Jacqueline Pollock, 6, died in a tragic car accident. One year later, their mother gave birth to twins, Gillian and Jennifer. When the twins were old enough to talk, they began identifying and requesting toys that had belonged to their dead sisters, pointing out landmarks only their dead sisters would have known (such as a school they'd attended), and sometimes panicking upon seeing cars idling ("That car is coming to get us!" they reportedly shrieked on one occasion).

After the twins turned five, these incidents became less frequent, and the girls went on to lead normal lives. Still, the story of the Pollock Sisters made its way to Dr. Ian Stevenson (1918–2007), a psychologist who studied reincarnation. After studying thousands of supposed cases, Dr. Stevenson wrote a book telling of 14 he believed to have been real, including that of the Pollock Sisters.

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10 / 19
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Where are the Sodder children?

Like the Pollocks, George and Jennie Sodder of West Virginia were forced to cope not only with the immeasurable loss of their children, but also with the mysterious circumstances surrounding that loss. After the Sodder home burned to the ground on the night before Christmas in 1945, five of the ten Sodder children were still alive and accounted for. But what about the other five? From all accounts, it would seem that they had vanished into thin air.

Notice how we don't say "vanished into smoke?" That's because in the ruins of the fire, zero physical evidence of the children could be found, which is virtually impossible from a scientific standpoint. But that wasn't all that smelled off about the events of that night. Apparently George tried to save the children, who he believed were still trapped inside by using his coal truck, which strangely, was inoperable; the phone lines to the house were found to have been cut; a woman claimed to have seen all five missing children peering from a passing car while the fire was in progress; and a woman at a Charleston hotel who saw the children's photos in a newspaper said she had seen four of the five a week after the fire. "The children were accompanied by two women and two men, all of Italian extraction," she said in a statement. "I tried to talk to the children in a friendly manner, but the men appeared hostile...and wouldn't allow it."

The Sodder family theorized that the children had been kidnapped, perhaps in an attempt to extort money, perhaps to coerce George into joining the local mafia (the Sodders were Italian immigrants), or perhaps in retaliation for George's outspoken criticism of Mussolini and Italy's fascist government. From the 1950s until Jennie Sodder's death in the late 1980s, the Sodder family maintained a billboard on State Route 16, with pictures of the five vanished children and offering a reward for information. The last (known) surviving Sodder child, Sylvia, 69, still doesn't believe her siblings perished in the fire.

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11 / 19
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What really happened to young Walter Collins?

In 2008, Clint Eastwood's film Changeling re-awakened interest in one of the most bizarre and tragic crime stories of the 1920s. Single mom Christine Collins reported her nine-year-old son, Walter, missing in March 1928 from their home in Los Angeles. Five months later, the police brought "Walter" back to Christine, except it wasn't Walter, and Christine knew it. But the LA police dismissed Christine's concerns, going so far as to accuse her of terrible mothering and having her committed to a mental hospital.

The real Walter Collins was never found, and over time, authorities came to believe he was one of the victims of convicted child-murderer Gordon Stewart Northcott, although Northcott's mother offered a confession for killing Walter. Whatever happened to Walter Collins, his body was never found, and no one ever learned what really happened. Nor has it been established with any certainty why the police were so invested in covering up the boy's disappearance that they brought a different child back to Christine and tried to convince her and the rest of the world that it was Walter.

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12 / 19
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The disappearance of Paula Jean Welden

Paula Jean Welden, 18, was a sophomore at Bennington College on Dec. 1, 1946, the day she told her roommate, Elizabeth Parker, she was going for a long walk but failed to return. A search focused primarily on Vermont's Long Trail (a 434-km trail that cut through Vermont to the Canadian border), where local witnesses reported having seen her.

The trail yielded no clues, however, and soon, what the Bennington Banner refers to as "tantalizing and unquestionably strange leads" began to materialize. These include claims by a Massachusetts waitress that she'd served an agitated young woman matching Paula's description. Upon learning of this particular lead, Paula's father disappeared for 36 hours, supposedly in pursuit of the lead, but it was nevertheless a strange move that led to his becoming a prime suspect in Paula's disappearance. Soon stories began circulating that Paula's home life was not nearly as idyllic as her parents had told the police. Apparently, Paula had not returned home for Thanksgiving the week prior, and she may have been distraught about a disagreement with her father. For his part, Paula's father posited a theory that Paula was distraught about a boy she liked and that perhaps the boy should have been a suspect.

Over the next decade, a local Bennington man twice bragged to friends that he knew where Paula's body was buried. He was unable to lead the police to any body, however, let alone Paula's, and with no evidence of a crime, no body, and no forensic clues, the case grew colder, and the theories grew stranger, including those linked to the paranormal. New England author and occult researcher Joseph Citro came up with the "Bennington Triangle" theory, which explained the disappearance as linked to a special "energy" that attracts outer space visitors, who would have taken Paula with them back to their world.

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13 / 19
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The Flannan Isles Lighthouse disappearances

In 1900, three keepers of the Flannan Isles Lighthouse off the west coast of Scotland disappeared under the strangest of circumstances.

The lighthouse was manned by a three-person team (Thomas Marshall, James Ducat, and Donald MacArthur), with a fourth man rotating in from shore. On Boxing Day (Dec. 26) of 1900, the relief keeper arrived to find none of the lighthouse keepers present. The only sign that anything was amiss was an overturned chair near the kitchen table. No bodies were ever found, which has led to endless speculation. Theories range from drownings to abduction by foreign spies, a ghost ship, or a giant sea monster. Whatever happened back in December 1900 at the Flannan Isles Lighthouse, we may never know.

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14 / 19
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The bridge at Overtoun that calls dogs to their maker

The Overtoun Bridge, near Dumbarton, seems to call dogs to leap to their death. Since the early 1960s, some 50 canines have perished, and hundreds more have jumped but survived, reports Slate via their Atlas Obscura blog, with some returning for a second leap onto the jagged rocks 50 feet below.

The Scottish Society for the Prevention of Cruelty to Animals has sent representatives to investigate but to no avail. In terms of scientific truth, it is debatable, if not incredibly unlikely, that dogs are capable of forming an intent to die. Yet, something is luring dogs off that bridge, often from the very same spot, and always on sunny, dry days. Many theories have arisen, including that the bridge is haunted (this was a popular theory after a local man threw his baby son to his death from the bridge in 1994); a mink is marking the area with an almost irresistible scent; and a sound anomaly exists at the bridge that only dogs can hear.

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15 / 19
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The big grey man

The Big Grey Man is an inhuman creature that is said to haunt the summit and passes of the second highest peak in Scotland, Ben Macdui (in the native Scottish tongue, the creature is known as Am Fear Liath Mòr). Like the Yeti of the Himalayas and Big Foot (also known as Sasquatch) of the American Pacific Northwest, the Big Grey Man has been seen by few eyewitnesses. What makes the Big Grey Man particularly frightening is that his physical characteristics don't resemble that of a bear, and thus sightings can't be dismissed as bear-sightings.

Those who have seen the Big Grey Man describe it as extremely tall (over 10 feet) and human-like, with short hair, broad shoulders, and long arms. Nearly all reports of sightings include the sound of gravel crunching beneath footfalls. Scientists haven't been able to come up with an explanation for the sightings and the accompanying sounds, although psychologists have proposed that those who have supposedly seen and heard the Big Grey Man have been in a state of physical and mental anguish brought on by exhaustion and/or isolation.

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16 / 19
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The lost colony of Roanoke

In 1587, John White led a group of people from Britain to found an English colony, settling on Roanoke Island, one of a chain of barrier islands now known as the Outer Banks of North Carolina. White left for more supplies, but on his return three years later, found the colony meticulously abandoned, with all houses and fortifications dismantled with care. Before he'd left the colony, White had instructed the colonists that if they were taken by force, they were to carve a cross into a nearby tree; but there was no cross. The only clue was the word "Croatoan," the name of a native tribe allied with the English, which was carved into a post. White took this to mean that the colonists had moved to Croatoan Island (now known as Hatteras).

Ensuing investigations turned up claims that the colonists had been slaughtered by the Powhatan tribe, but there is no archaeological evidence of this, and a recent re-examination of the primary sources indicates that any massacre that occurred was not of this particular group of colonists, but rather a group of colonists who had arrived earlier. More enduring theories involve integration between the colonists and the Croatoans or other local tribes, but so far, no DNA evidence has positively identified any descendants of the colony.

17 / 19
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The Circleville letters

In 1976, residents of Circleville, Ohio, began receiving hate-mail that has wreaked havoc ever since. The letters, postmarked from Columbus, were invasive and accusatory, highlighting a supposed affair between school bus driver Mary Gillespie, and the school superintendent. One letter addressed to Mary's husband Ron, threatened his life if he didn't put a stop to the affair. By 1977, the husband was dead, the result of a suspicious one-car crash involving shots fired. When the Sheriff ruled the death an accident, however, residents began receiving letters accusing the Sheriff of a cover-up. The letters continued throughout the 1970s and early 1980s, and even after Ron's sister's husband, Paul Freshour, was convicted of writing the letters and attempting to murder Mary via a booby-trap-rigged pistol.

Even with Freshour in prison, however, the letters continued. He even received one himself. In 1994, Freshour was released, and he maintained his innocence until his death in 2012. The true identity of the Circleville Letter Writer remains unknown. Some still believe it was Freshour. Others believe it was Mary, herself, and that she used the letters to concoct and support the perfect murder of her own husband.

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18 / 19
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The Tunguska event

On the morning of June 30, 1908, 2,013 square kilometres of forest in Siberia, Russia were flattened by what would have appeared to have been an explosion, except that there were no witnesses and no other evidence. The phenomenon, known as the Tunguska event, has been classified by scientists as the largest "impact event" (which means a recordable impact between two astronomical objects, such as an asteroid and the earth) in recorded history. Yet no "impact crater" has ever been found (which would be an important earmark of an impact event). Thus, scientists can only surmise what may have happened, which may be that an asteroid exploded over the earth, and the destruction that ensued beneath it in Siberia was the result of after-effects.

19 / 19
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The disappearance of Malaysian Airlines Flight 370

On March 8, 2014, while flying from Malaysia to China, a Boeing 777 carrying 239 passengers and crew members seems to have vanished into thin air. The multinational search effort, the largest in aviation history, has turned up a mere 20 pieces of aircraft debris. The Prime Minister of Malaysia has declined to comment other than to say that the aircraft disappeared over the Indian Ocean. The lack of closure has engendered multiple theories, many of which are considered "conspiracy theories," which, according to Harvard professor, Cass Sunstein, are a natural product of "horrific and disastrous situations, because such events make people angry, fearful, and looking for a target."

Theories include hijacking, capture by the U.S., crew suicide (it was reported that the pilot was having marital problems), a fire aboard the aircraft, vertical entry into the sea, a meteor strike, and even alien abduction. Notwithstanding the passage of three years and the expenditure of $160 million scouring thousands of square kilometres of ocean, the disappearance of Malaysian Airlines Flight 370 and the 239 people aboard remains a mystery.

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Originally Published on Reader's Digest