UFOs: What Are They?
What are UFOs, really? If you pose that question to a fervent believer who pours over testimonies from supposed alien abductees and reports of mysterious lights in the nighttime sky, you'll hear that they probably are spaceships from other worlds. A hard-core skeptic, on the other hand, is more likely to tell you about atmospheric conditions that produce false blips on radar, eager untrained observers who mistake aircraft lights or military flares for alien craft, and photos doctored by hoaxers.
In between those two extremes, those who've studied the UFOs over the years have offered a range of different explanations. Given the general lack of tangible evidence and the difficulty of testing any of these notions, it's probably more accurate to call them hypotheses rather than theories. But here are some of the most popular and/or intriguing possible answers. It's important to note that what we describe generically as UFOs may not all be the same thing; instead, it's entirely possible that the category includes multiple phenomena with vastly different explanations.
The Extraterrestrial Explanation
This is an answer that would make a lot of people with those "I Want to Believe" posters in their bedrooms very happy. On the plus side of the ledger are eyewitness reports which include details that sound like design features of spacecraft. For example, Japanese airline pilot Capt. Kenju Terauchi, who encountered a UFO while flying over northern Alaska in 1987, described a craft 500 to 1000 feet away that consisted of "two dark cylinders with row after row of spinning amber lights, one row spinning in one direction, the next in the opposite." On the problematic side, in the 2002 book "The Science of UFOs: What If They're Real?" astronomer William A. Alschuler notes that some of the high-speed maneuvers ascribed to UFOs would exert such enormous forces that it's difficult to imagine how living creatures inside could survive them. Of course, it's also possible that a technologically advanced alien civilization could have solved such a problem.
The Nazi Flying Saucer Explanation
For decades, there's been speculation—most recently, in British journalist Nick Cook's book "The Hunt for Zero Point: Inside the Classified World of Antigravity Technology" that during World War II, German scientists developed a flying saucer equipped with an antigravity propulsion engine. As the storyline goes, U.S. forces may have captured the plans or even a prototype device and brought it back to this country, where government scientists secretly tried to further develop the technology. There's also suspicion that some UFO sightings may actually be flights of other nations' top-secret experimental aircraft, which might explain why declassified CIA files contain so many accounts of UFO sightings abroad.
The Atmospheric Explanations
Ball lightning, reflected light from clouds, and other natural phenomena are often cited as an explanation for what observers think are UFOs. Air Force officials tried to explain away air traffic controllers' sightings of UFOs in the Washington, DC area in 1952 as a glitch on their radar screens caused by a temperature inversion, in which a layer of warm, moist air covered another cooler, drier layer closer to the ground.
The Electromagnetic Explanation
Many reports of UFOs, Alschuler writes, describe lights that lack form or surface. One hypothesis offered by UFO skeptics is that what witnesses are actually seeing visual effects caused by the shifting of parts of the Earth's crust, which in turn would lead to temporary disturbances in electromagnetic fields above the Earth's surface. Some people have reported seeing similar lights near the ground just prior to earthquakes. Interestingly, it might also be that these external magnetic field disturbances somehow directly affect witnesses' nervous systems. That would mean that people would report seeing lights that essentially exist only inside their brains, and that video and still cameras would not be able to record them.
The Power-of-Suggestion Explanation
Alschuler notes that over time, the proportion of various UFO shapes reported by witnesses has shifted. Initially, cigar-shaped UFOs seemed to predominate; later, saucer-shaped craft began to show up in reports, and most recently, the cigar shapes and saucers have given way to wedge-shaped craft. Those trends, perhaps not coincidentally, have closely tracked the changing depiction of extraterrestrial spacecraft in science fiction magazines, movies and television over the course of the 20th Century. That raises the question of whether UFOs actually are some sort of mass psychological delusion, akin to the hysteria about witches in 17th Century Europe and America, or the widespread belief in late 19th and early 20th Century England in the existence of fairies (which was stimulated by what now seem to be obviously phony photographic images of tiny sprites taken by spiritualists). For whatever reasons, it could be that witnesses are reporting what they believe alien spaceships are supposed to look like, rather than describing actual objects.
The Scam Explanation
In a 2003 article for the Skeptical Inquirer, Swedish astronomer and planetarium show producer Tom Callen notes that numerous photographic images of purported UFOs over the past seven decades subsequently were exposed as frauds. To demonstrate the ease of perpetrating such hoaxes, Callen and colleagues actually recreated a number of iconic UFO pictures by building plastic models of saucers, photographing them, and superimposing the images over photographs of various locations in Stockholm. The results, he wrote, could fool anyone, "except for those who investigate such seemingly incredible images and understand how easy it is to make them."
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