>> NARRATOR: Magnificent monoliths, mysterious carvings, And legends of winged creatures visiting from other worlds. Have alien astronauts been visiting the Earth for thousands of years? >> GEORGE NOORY: Extraterrestrials are coming to this planet, and they're doing some very strangely evil things. >> NARRATOR: Or might mainstream science, the government, the media, and even academic institutions, all be part of an elaborate conspiracy to keep us from knowing the truth? >> SARA SEAGER: There is no robust evidence that aliens have ever visited Earth. >> DAN QUAYLE: We spent some time looking at this, but there was nothing conclusive. >> NARRATOR: But if so, why? >> PHILIP COPPENS: This cover-up, this technology, disappears within the confines of the mily industrial complex. >> NARRATOR: There are those who believe in the existence of a book. A book that contains the most highly guarded secrets of the United States of America. A book... whose very existence is known to only a select few. But if such a book exists, what would it contain? Secret histories? Secret discoveries? Secret lies? Does there really exist <i> America's Book of Secrets?</i> >> NARRATOR: The notion of a universe inhabited by alien creatures can be found just about everywhere in American popular culture. Especially in movies, books, and on television. But as far as the mainstream is concerned, the idea that life on other planets not only exists, but has, at any time, made its way to our planet, is considered the stuff of science fiction. And those who differ with that conventional wisdom are subjected to ridicule, scorn and, in some cases, government scrutiny. >> GIORGIO TSOUKALOS: Just because<i> we</i> can't travel from star to star, doesn't mean another civilization, who is poteially 10,000, if not a 100,000 years older than us, can't do it either. That's the height of human arrogance, yet we are saying, "Oh, this is just nothing but fantasy." >> NARRATOR: Could mankind really have been visited by alien beings from other worlds? And might the truth have been kept secret for centuries? Roswell, New Mexico. Here in the flat, thirsty lands of the American Southwest, lies a remote city of 50,000 residents. Once the home of America's largest Strategic Air Command base, it has now become ground zero for UFO-ologists and believers in all things extraterrestrial. Thanks to an incident that happened on the evening of July 8, 1947. (thunder crashing) >> JULIE SHUSTER: Following a major thunderstorm, rancher Mac Brazel came across this really extensive area of debris, stuff he had never seen before. He brought it to the local sheriff's office. They both thought it might be military because in 1947, Roswell was home to Roswell Army Airfield and home of 509th bomb wing. The base sent Major Jess Marcel, the intelligence officer, and at that point it basically became a military site as they gathered up every bit of debris they could find. >> JIM MARRS: Early on, they issued an official sanctioned press release from the Roswell Army Airfield saying, "We have captured a flying saucer." The next day, higher authority said, "Uh, uh, no, wait, wait, wait, uh, no, they were wrong. It was just a weather balloon." >> COPPENS: Something clearly landed in 1947. I've personally spoken with the Jesse Marcel family, and they're absolutely convinced that what they saw was not of this Earth. He knew what a weather balloon was, he knew that this wasn't a weather balloon. >> MARRS: They moved in with the military, they scraped up the whole area and they have since tried to act like nothing had happened. >> MICHAEL SHERMER:<i> National</i> <i> Inquirer</i> took the story and ran with it and that made it even more popular. And the moment that happens, you can start to count, like, the number of column inches devoted to a subject. (camera shutter clicking) And that's what generates a myth. >> NARRATOR: The Air Force added more twists to the Roswell mystery beginning in 1994 with a statement that what crashed at Roswell came from a top-secret experiment called Project Mogul. Three years later, the Air Force reported that the alleged alien bodies were in fact dummies attached to parachutes as part of a flight test. >> MARRS: Except that doesn't make any sense either because if you're gonna test ejection seats or cockpits or parachutes or whatever, you're gonna use a human-sized dummy, right? You're not gonna use a four-foot high, big-headed, alien-looking creature. So the whole thing is just, it's just almost laughable. >> NARRATOR: The Air Force's conflicting reports about what was recovered at Roswell ignited the flames of a conspiracy theory that continues to this day. But why the changing stories? What was-- or is -- the government hiding? >> MARRS: I think the truth is that something very unusual happened at Roswell. Now how many aliens there were, and what kind of ship it was, and where it came from-- we don't know because they've covered it up. They've hidden it away. >> NOORY: They might think we can't handle the truth. They may think that they can't control us. There could be all kinds of causes and reasons for the suppression. Maybe they were told not to tell us. And so one of the reasons could very well be why government does not tell us why they keep this, this book of secrets is simply to protect us from panicking. >> JONATHAN YOUNG: If there is evidence, allegedly the government would want to keep that a secret, hide it in a warehouse out in the desert some place. >> MARRS: The key motives for keeping the UFO, extraterrestrial issue secret falls into, I think, two broad categories. Number one, uh, weaponry. They view any exotic technology as possible weapons and therefore, it's got to be kept secret. And number two, any advanced technology could shake up the monopolies that the ruling elite enjoy in this country and so they've got to keep that secret. (camera shutter clicking) >> NARRATOR: But where is the proof that the government hid advanced technology found at Roswell? >> MARRS: I think a tip off to the fact that we got a hold of E.T. technology at the Roswell crash, is simply for the fact that up until about 1947, '48, '49, technological advancement was one of slow evolution. But after about 1950, you saw a literal explosion of technology. Fiber optics, night vision, computerization. Where did all that come from? I think we were picking up technology from some other outside source. >> NARRATOR: Might the U.S. government's advanced weapons technologies have been the result of access to extraterrestrial intelligence? According to authorities, such theories are absurd; the lunatic notions of a conspiracy-hungry public. >> DAVID CHILDRESS: In many ways, the mainstream completely marginalizes the idea of extraterrestrials coming here. They give it no credibility at all. And yet, what is so strange about the idea that extraterrestrials should come here? We know we're probably not alone in the universe. And we ourselves are trying to go to other planets. Why wouldn't they come here? >> NARRATOR: For those who adhere to the audacious notion that planet Earth is no stranger to alien visitation, evidence can be found in historical events from the ancient past. And for some, the proof is right before our eyes. >> ASTRONAUT: Contact light. Okay, engine stop. >> FLIGHT CONTROL: We copy you down, Eagle. >> ASTRONAUT: Tranquility Base here. The Eagle has landed. >> NARRATOR: On July 20, 1969, in what was arguably mankind's greatest technical achievement, Apollo 11 astronauts Neil Armstrong and Buzz Aldrin became the first humans in hiory to step foot on the moon. >> ARMSTRONG: That's one small step for man, one giant leap for mankind. >> NARRATOR: More than 125 million people watched the event live on their television screens, but then for a period of two nail-biting minutes, the transmission suddenly went dead. The official reason was technical difficulties, but there are many who believe those two minutes were recorded but censored due to the strange things the astronauts were reporting back to NASA. >> JASON MARTELL: Neil Armstrong and Buzz Aldrin actually saw things taking place on the dark side of the moon. And they were told they were not allowed to go there. And these were not Earth-based technologies. >> CHILDRESS: Neil Armstrong allegedly saw a UFO lifting up out of a crater on the moon. >> MARRS: Armstrong said, "Wow, look at the these babies. They're huge." And that they were, uh, ships up there watching them. >> NARRATOR: UFOs on the moon? Witnessed by astronauts Neil Armstrong and Buzz Aldrin? A delusional conspiracy theory? Or a government cover-up? Two facts are certain: the world watched as beings from one world landed on another, and a book published just one year earlier was now flying off store shelves. Written by Swiss author Erich von Daniken,<i> Chariots of the</i> <i> Gods?</i> made a compelling case for the notion that many of the world's ancient archaeological mysteries had other-worldly origins. >> CHILDRESS: The whole idea is extraterrestrials have been coming to Earth for thousands of years. >> ERICH VON DANIKEN: The best case worldwide is Nazca. I was one of the first who was in Nazca. Nazca is in Peru about 500 kilometers from Lima. When you fly over the desert, you see gigantic lines. They look like airstrips. Seen from the air, they give you the imagination of airstrips. They look like. Because they start abruptly, end abruptly. >> NARRATOR: Von Daniken's book also reported findings in the western United States of cave paintings of gods resembling strange creatures from another world. And other ancient images could be found in Italy that bore a striking resemblance to astronauts in space suits. >> VON DANIKEN: We have worldwide similar cave paintings. The so-called gods are always the one with the helmets and their halos. Now, if something happened just on one continent, let's say, the Africans would do this, I would be quiet. But I clearly can prove that these so-called gods, with the helmets and the halos, you find worldwide... thousands of of years ago when our forefathers had no connection to each other. So why this? Because they saw the same thing. >> NARRATOR: Within a year of Neil Armstrong's first walk on the moon,<i> Chariots of the</i> <i> Gods?</i> had sold 60 million copies and had been printed in 32 languages. It ignited belief in what has since become known as the ancient astronaut theory. But it also sparked controversy, even derision, from archaeologists, religious scholars, academics and even the mainstream media. >> VON DANIKEN:<i> Chariots of</i> <i> the Gods?</i> was on the market in the German-speaking world in February, 1968. About one and a half months later, it was on top of every best-selling list. And it took about maybe three or four weeks, then the critics began. >> SEAGER: It was outrageous. It collected a bunch of things and put them together in a way that was completely outlandish, yet so compelling that people wanted to believe it. And people want to believe that aliens visited Earth in the past and that they helped us with the pyramids and with the Nazca lines and that ancient aliens gave us technology. But the reality is, there is no robust evidence that aliens have ever visited Earth. >> SHERMER: A theory incorporates a whole bunch of different hypotheses and facts and evidence, all converging to a particular conclusion. In this case, that we were visited by aliens in ancient times and the fact is we weren't. There's no, no evidence for this at all. >> MAX TEGMARK: If there were an American book of secrets about extraterrestrials, it would say there that the only species able to colonize our universe is us. >> NARRATOR: Nine months after his book's release, Erich von Daniken was arrested for fraud, embezzlement and forgery in connection with loans he had secured to finance his research. A coincidence? Or a punishment intended to discredit and even silence his increasingly popular theory? >> CHILDRESS: There's a natural suppression of this idea that extraterrestrials are here. And, even if there is overwhelming evidence for it, even the governments are going to want to keep a lid on this. >> TSOUKALOS: The ancient alien theory has been looked down upon by academia for a very long time, and that's okay, because we have to understand that science always has this status quo. And it's the status quo that needs to be maintained. >> COPPENS: 40 years later, the questions are still out there, and some are still being posed. And science is still coming up with no answers, because for 40 years, they have been unwilling to address it. >> YOUNG: The possible conspiracy would be there is such power in these ideas, revolutionary world-changing social upheaval could follow if in fact these all came out. >> NARRATOR: Could there really be a global cover-up of ancient alien activity? One that shields the public from a profound knowledge that, if revealed, could shatter the very ic of our civilization? Even distinguished NASA astronaut Edgar Mitchell, the lunar module pilot for Apollo 14 and the sixth man to walk on the moon, says the answer is... yes. >> EDGAR MITCHELL: I think that the evidence of E.T.s and aliens being here, which I'm convinced they have been, are sufficient evidence in itself. That they come from some other place. >> COPPENS: What we're going to find is not only that we are not alone, but also that our entire history needs to be reanalyzed. Everything-- what we know about the past-- all of a sudden has to become inclusive of visitors from elsewhere. >> NARRATOR: In 1974, Sunn Classic Pictures, an independent production company specializing in family-friendly documentaries, released a feature film version of <i> Chariots of the Gods</i> to theaters across the United States. Grossing nearly $26 million, it helped fuel the flames of a growing interest in the ancient astronaut theory. >> SHERMER: When<i> Chariots</i> came out, I was in college, and I remember it was a big pop culture thing. I mean, it was a huge story, and I thought that this would be fantastic if there was something to this. >> TSOUKALOS: For the first time ever, the idea that extraterrestrials might have visited Earth in the remote past was being popularized. You have to understand that in the '70s, the country was in upheaval, people were unsatisfied with what was going on in politics and all this-- very reminiscent of what is happening today, by the way. >> NARRATOR: The willingness on the part of the American public to embrace many of the film's audacious claims was due in no small part to a growing cynicism and antiestablishment attitude, one that took root in the era of Vietnam war protests and the Watergate scandal, particularly with the generation known as baby boomers. Now everything was being questioned, especially organized religion and even the existence of God. >> SHERMER: The slow erosion of mainstream religion and the rise of new age spiritualities and that sort of thing, the alien hypothesis became much more popular. There was a more of a receptive audience for it-- that there are beings out there coming down here-- which then finally also has religious overtones. >> YOUNG: Von Daniken takes a very stimulating theological stance. He has an explanation for the gods that both questions and challenges traditional explanations of what gods are or what God is. >> TSOUKALOS:<i> Chariots of</i> <i> the Gods?</i> was quite timely because we ourselves just became extraterrestrials on the moon. Space exploration at the time was huge. (weapons zapping) >> NARRATOR: Even more evidence of the ancient astronaut theory's growing attractiveness could be found in popular culture, primarily in films like <i> Star Wars,</i> which places its high-tech world of robots and lightsabers not in the far future but "a long time ago in a galaxy far, far away." Similarly popular was<i> Battlestar</i> <i> Galactica,</i> a fantasy adventure television series which told the story of a doomed humanoid race in search of a home planet. Its use of Egyptian-style spacesuits and other ancient iconography seemed to validate von Daniken's notion that the people who built the pyramids may in fact have come to Earth from other worlds. >> SHERMER: The idea of there being extraterrestrials out there, this is called the plurality of worlds debate. It's been around since the ancient Greeks. So it's just a small extension to go from, "They're out there," to "They've come here." >> NARRATOR: But there were those for whom the idea of extraterrestrial beings traveling to Earth and influencing its history represented not a far-fetched theory but the lowest and most dangerous form of pseudoscience. They called ancient astronaut theory everything from "racist" and "colonialist" to downright nonsense. And these were members not only of the religious and scientific communities but of the presumably more open-minded world of academia. >> COPPENS: When<i> Chariots of</i> <i> the Gods?</i> came out, it created a revolution because people either loved it or hated it. Mostly, the ones who hated it were the academics because they somehow felt that this notion that we had been visited by extraterrestrial beings was simply impossible. Erich von Daniken had to be wrong. And what they were confronted with was the fact that these questions couldn't be answered by science. Science was basically saying that there was no validity whatsoever. >> TODD DISOTELL:<i> Chariots of</i> <i> the Gods?</i> actually really did have an effect on me because when I see what I call outright bad science, it really gets my hackles up, and when I listened and read about and saw different shows on these different hypotheses, it often ended up sort of screaming matches at the television screen about, "That's the dumbest thing I ever heard." >> TEGMARK: I don't think the Earth has ever been visited by any extraterrestrials. I find it striking how we humans have again and again underestimated the technological capabilities of ancient peoples. We tend to be a little bit arrogant and say, "Ah, those loser Egyptians and Greeks, you know. What do they know?" >> NARRATOR: Is ancient astronaut theory really as anti-scientific or preposterous as its detractors believe it is? Or could there be another, perhaps more secret reason for the mainstream resistance to the idea that alien visitors have been coming to Earth for centuries? >> YOUNG: Having a new idea of religion, a new revelation of sorts is gonna challenge any established belief system and the institutions that support that belief system, that established economic interests would be concerned about the technology, the advances, that it could disrupt markets, could disrupt their own financial interests. >> NARRATOR: But there is one branch of the government that is reportedly very open to the idea of extraterrestrials in our midst... the presidency. In his first days in office, President Bill Clinton is said to have asked two questions: who really killed President Kennedy? And what is hidden at Area 51? >> BILL CLINTON: If the United States Air Force did recover alien bodies, they didn't tell me about it either, and I want to know. >> NARRATOR: The administration of President George H.W. Bush also made a secret investigaon into the possibility of alien visitors on planet Earth. >> QUAYLE: The alien situation is very interesting. We literally spent some time looking at this, but there was nothing conclusive that came of it. >> NARRATOR: "Nothing conclusive"? Can it really be that the nation's highest office cannot confirm or deny that alien visitors on Earth do not exist? Or... is it possible that the truth about UFOs and alien astronauts is being kept hidden-- even from the president? >> NOORY: I think most presidents have tried to find out what's going on, and I don't think they get through the door. I don't think they're told. But there's that very high likelihood that the secret is here and we don't know about it. >> COPPENS: Various people in the Obama administration have expressed a deep interest in UFOs. But in all cases, what we hear is that somehow the UFO secret is not something which is to be shared to the president. >> MARRS: So that means the President of the United States cannot even get to this information, which I think should raise the question in everyone's mind: well, who <i> does</i> get to this information... and who exactly are<i> they</i> to keep it from everyone, including the president? >> NARRATOR: The relationship between the President of the United States and otherworldly beings stretches back to the very founding of the country. From its earliest days, the U.S. government has been associated with signs... symbols... and allusions to cosmic contact. >> CHILDRESS: The Founding Fathers of America were very open-minded and forward-thinking people. Thomas Jefferson reported seeing a UFO. Benjamin Franklin wrote that he beeved in life on other planets. Even George Washington had a portrait made of himself that has a UFO in the sky. So, you have this idea of the Founding Fathers even possibly being influenced themselves by extraterrestrials. >> NARRATOR: But why, if the nation's highest office remains curious about the possibility of alien visitors, is the notion so scoffed at by those in the scientific community? Is there a cover-up? Or do they think mankind is not yet ready... to handle the truth? Perhaps the answer lies in the Book of Secrets. >> NARRATOR: On May 13, 2008, the<i> L'Osservatore Romano,</i> the semiofficial newspaper of the Catholic Church in Rome, published an interview with Reverend Jose Gabriel Funes, the Jesuit priest who served as director of the Vatican's observatory at Castel Gandolfo, near Rome. (beeping) (camera shutter clicking) Bearing the headline, "The Extraterrestrial is my brother," Funes made a remarkable and audacious admission-- that there is no conflict between believing in God... and the possibility of intelligent life on other planets. In one swift move, the Roman Catholic Church had contradicted centuries of its own teachings. >> MARTELL: This would really break the mold of our current understandings of religion. And understand that a lot of the things we thought were mythology were actually fact. >> NARRATOR: Why the change in attitude? Did the Catholic Church discover evidence of life on other planets? Or might it be the time was right for the Church to admit something... it had known to be true all along? >> MARRS: The Vatican has some of the most advanced telescopes in the world. They have some of the most advanced radio telescopes and transmission and communication equipment in the world, and I think they know the same things our military-industrial complex knows, which is this is all very real, and that eventually it's gonna come out. >> TSOUKALOS: I think the reason why the Vatican came forward and endorsed the idea of a search for extraterrestrial life is because the Vatican wants to be ahead of the curve. >> NARRATOR: The Vatican observatory's announcement also included plans to explore the outer planets and their systems, with a particular concentration on Saturn's moons, Titan and Enceladus. >> CHILDRESS: They said that <i> they</i> would be involved with the search for extraterrestrial life. So suddenly the Vatican is saying, "Yes, there's other life on other planets. We're gonna be looking for it, too." >> NARRATOR: Could Saturn's moons really hold the key to the extraterrestrial origins of life on our planet? And is the Vican really admitting that the Earth's ancient religions might, in fact, have extraterrestrial origins? Even believers in ancient astronaut theory remain skeptical. >> CHILDRESS: The idea that the source of ancient religions might actually be interaction with extraterrestrials is not an idea that organized religion wants to promote. >> MARRS: What's at stake for organized religion? (scoffs): Power and control. It's that simple. >> NARRATOR: There are many in the ancient astronaut community, however, who claim that many of the beliefs and teachings that comprise the world's religions serve not to contradict the possibility of alien life, but to confirm it. >> TSOUKALOS: One of the biggest points of reference fothe ancient alien theory are the sacred books, sacred texts, that we can find all around the world. And those sacred texts, in many cases, describe people from the stars descending in some type of flying machi >> NARRATOR: The Vatican's bold admission that the possibility of intelligent life in the universe seemed to validate what scientists and cosmologists, like Stephen Hawking, had believed for centuries. But it also gave fresh credibility to another, perhaps even more controversial theory, that of intelligent design. >> TED PETERS: Intelligent design is a theory, having been... promoted now for about two decades, that says evolutionary development is not strictly a matter of chance; that actually, higher organisms are designed, and designed by an intelligent designer. They're not simply accidents of biological contingency. >> NARRATOR: Of course, the notion that the universe, and all living things, are more likely the product of a godlike being or entity was not new-- virtually every religion across the globe has embraced the concept for centuries. But intelligent design was now being championed by powerful political and religious conservatives-- people like Republican Party activist George Gilder, whose Discovery Institute in Washington, DC, stands at the forefront of what detractors would call this "subversive" and "pseudoscientific" concept. It was seen by the mainstream as an attack on the theory of evolution, and therefore threatened the integrity of modern scientific thought. >> PETERS: Those disciples of Charles Darwin, who advance evolutionary theory-- and today we call it the "neo-Darwinian synthesis," because genetics explains variation-- it's important to note these are chance events that lead to the development of new species. Intelligent design people want to say it's not just chance, it's the intervention of an intelligent designer. Who is that intelligent designer? Well, St. Thomas Aquinas would say, "We all call that designer God," but intelligent design people say, "We have no opinion on who the designer is." >> NARRATOR: Do proponents of intelligent design really have a secret agenda to undermine conventional science by promoting the belief in an almighty creator, or is it an ingenious means of bridging the enormous gap that exists between those who believe in Charles Darwin's secular theory of evolution and those who believe that mankind might also owe its very existence to beings from other worlds? Perhaps the ultimate answer can be found in the covert messages that are being transmitted thughout our galaxy even as we speak. >> NARRATOR: 290 miles north of San Francisco is an open field that many scientists believe could hold the key to contact with extraterrestrial intelligence. (camera shutter clicking) At the Allen Telescopic Array, radio receivers and giant transmitters are part of a global scientific network called SETI. >> TEGMARK: I think that the goal of the SETI program, the Search for Extraterrestrial Intelligence, is extremely important. We look at our universe and we just have to know: are we alone, or is there anybody else out there? >> NARRATOR: Among SETI's favorite cosmic targets are areas called Goldilocks zones. >> SEAGER: The Goldilocks zone is a zone around a star where the temperatures are not too hot, not too cold, but just right for liquid water to exist. All life on Earth requires liquid water, so we believe that the best way to search for other planets with life is to search for planets that have liquid water, and just as technology has begun to see planets that may be able to have life, that type of planet appears to be everywhere. >> TEGMARK: So the million- dollar question is if we can find that otherwise decent planet around a star in its Goldilocks zone because that's where we have the greatest chance of finding extraterrestrials. (beeping) >> NARRATOR: Could there really be an abundance of livable planets in the universe, and might SETI really detect intelligent life on one of them? But how? >> MICHAEL DENNIN: There's two senses in which you could detect intelligent extraterrestrial life. One is in, in just the noise that they generate. (car horns honking) (overlapping chatter) (whistling) If you think about our society, we now have TV, we have cell phones, we have all sorts of technology that radiates out into space, um, and could in principle be detected. (garbled radio transmissions) (car horns honking) (bell tolling) The other is, we have changes in our atmosphere that we generated by being on the planet and doing stuff, that in principle could be detected. >> COPPENS: It is very much like looking for a needle in a haystack because we're using radio astronomy. We're analyzing radio waves in an effort to try and find out whether, amongst the millions of signals which we get on a daily if not hourly basis from space, whether somehow in there is an alien communication. >> NARRATOR: Could the very existence of SETI along with NASA's missions to Mars and other planets be proof of the U.S. government's secret belief in the ancient astronaut theory, and if so, would we be prepared in the event of a real-life close encounter? >> CHILDRESS: UFO activity has been going on for thousands of years, and we have been monitored and watched since the beginning of our civilization. >> MARRS: The U.S. military and even the United Nations has stored away some contingency plans in the event that aliens should show up, you know, either benign or otherwise. They would be remiss in their job if they didn't have such contingency plans. >> NARRATOR: Are there secret files and covert plans under lock and key? Have there been exercises and other preparation work? If the truth finally comes out, might proof of life on other planets crumble the foundations of government, religion, science, and our society, or would it reassure us by revealing at last the truth about our origins? >> TSOUKALOS: If an American Book of Secrets existed, then the chapter on ancient astronauts would suggest that we shouldn't look for our origins on planet Earth but that in fact our origins... lie out there. (garbled radio transmission) >> NARRATOR: Might SETI be on the brink of an incredible discovery? Or are they, as some experts warn, setting planet Earth up for a mega-disaster? >> TEGMARK: Transmitting signals into space saying, "Hey there, here we are" is an absolutely idiotic thing to do. I mean, seriously you don't scream in the jungle. If you were a pig living on an island of pigs, very happily doing all your piggly stuff, would you like for the human neighbors on the island next to you to know that you're there? (pig squealing) Don't think so. We humans are newbies on this stage. We don't know who's out there. >> MITCHELL: If they were hostile and wanted to end the experiment we call humanity here, they could do so because they would have the technology to do so. >> NOORY: If this universe is made up of the same primordial soup, then you have to assume that not every being in this universe is enlightened and nice. It's very possible that there's a sect of extraterrestrials that are coming to this planet and they're doing some very strangely evil things. >> TSOUKALOS: Dr. Stephen Hawking suggested that SETI should stop sending out signals or searching for signals because the moment that extraterrestrials found out that we are here... they would come here to destroy us. (explosions) >> NARRATOR: Has the United States government really conspired with other nations to hide the facts about mankind's extraterrestrial past? Is there really a cover-up, or is the notion of life on other planets too bizarre to be believed? Perhaps the truth will never be known until the day when they return. <font color="#FFFF00"> Captioned sponsored by</font> <font color="#FFFF00"> A&E TELEVISION NETWORKS</font> Captioned by <font color="#00FFFF"> Media Access Group at WGBH </font> access.wgbh.org
