Carter Roy (17:59)
The Fermi Paradox was a thought experiment first posed by enrico Fermi in 1950. The paradox questions why we have not yet encountered intelligent extraterrestrial life, even though the incredible scale of the universe suggests that there is a high probability of it existing. In 1975, physicist Michael Hart published a paper called An Explanation for the Absence of Extraterrestrials on Earth, which argued that because we haven't seen alien life, it must not exist. Hart's paper stoked aflame within the scientific community as fellow scientists also sought to find their own answers to the Fermi paradox. One of those scientists was physicist Frank Tipler. He asked, even if a civilization were advanced enough to travel through space and colonize a galaxy, where would they get enough physical supplies to do it? In his paper, Tipler suggested that a civilization would need some sort of technology that would efficiently replicate the tools necessary for space colonization. He suggested a self replicating universal constructor with intelligence comparable to the human level. By this logic, a civilization would send one of these constructors to a neighboring star, have the constructor build copies of itself using materials from that star system, and then send those copies to other stars. That way, the constructor could continue to build civilizations across a galaxy. Tipler argued that since we don't have such devices on Earth and we still have yet to see extraterrestrial life, it proved that such universal constructors and the aliens that would build them do not exist. If we are to take Hart and Tipler at their word that humanity is the only advanced life form in the universe, then the question becomes why? What is it that makes us unique? One answer to this question is found in the notion of the Great Filter. The Great Filter, named as such By Robin Hansen, a professor and researcher with experience working on DARPA or the Defense Advanced Research Projects Agency, is a theory that argues that at some point during a species evolution, it will hit a wall. This wall is the point at which it's extremely difficult or impossible for life to continue, such as some sort of inevitable apocalypse. That point is known as the Great Filter. The Great Filter could manifest in many different ways, whether it be resource scarcity, a natural limit to technological advancement, or a catastrophic astronomic event. If we propose this as a solution to the Fermi Paradox, what follows are two possibilities for humanity's place in the cosmos. The first is that we have already crossed the threshold of the Great Filter. We defy the odds that less evolved species before us were unable to overcome, and we will hopefully continue to evolve into an even more advanced civilization. Perhaps the universe was more hostile in the past, but over time, conditions became more conducive to life. The universe passed the Great Filter, and thus humans were able to evolve. We might be one of the few intelligent civilizations, if not the only one, in the universe. If we are unique as an intelligent civilization, it could be attributed to what is known as the Rare Earth Hypothesis. Even though there may be many Earth like planets in the universe, the specific conditions of Earth, such as our moon or the molecular composition of the planet, make it specifically suitable for life in a way that very few planets are. It would be a lonely reality, but it would also provide hope that humanity could evolve enough to become the first civilization to explore the galaxy. Unfortunately, the other possibility for humanity in the context of the Great Filter is bleaker, much bleaker. This alternative explanation says that the Great Filter is ahead of us. It suggests that there are certain filters that exist all across the universe. And at various points, different civilizations are filtered out. That is to say, they go extinct because they can't make it past some sort of obstacle. The universe is a fundamentally hostile place, and because of this, according to this theory, civilizations are not given enough time to evolve fast enough to avoid this Great Filter. This could manifest as some kind of naturally occurring cataclysmic event, like gamma ray bursts. Or it might be something that the civilization itself creates, like a nuclear apocalypse. It would be an inevitability that nearly all intelligent civilizations wind up destroying themselves after they reach a certain level of technological advancement. Simulation theory obviously plays well with this idea. If intelligent life was engineered by an unknown entity, these engineers could be testing for a civilization's ability to overcome the Great Filter. In this case, a naturally occurring Great Filter could be A cosmic disaster put in place by engineers to end the simulation. So we are not able to make contact with any other civilizations because they are either too unevolved to have the technology to reach us, or they've been wiped out by a great filter. Michael Hart and Frank tipler's arguments in 1975 and 1980 open the possibility that we are, in fact, alone in the universe. The reason we have yet to find incontrovertible proof about extraterrestrial life is because there is none. The universe is a vast and complex place, but perhaps for one reason or another, life, and in particular sentient life, is an incredibly rare phenomenon. But there are many scientists who think differently. Yes, there is no physical evidence of aliens, but there is also still no physical evidence that there aren't aliens either. Which brings us to the second solution to the Fermi paradox. Extraterrestrial life does, in fact exist in the universe, but for one reason or another, we have not observed it yet. Scientists Carl Sagan and William Newman argued against Hart and tipler in a 1983 paper titled the Solipsist Approach to Extraterrestrial Intelligence. In their paper, Sagan and Newman used mathematical models similar to the ones population biologists used to estimate animal populations. With those calculations, they concluded that the rates of a civilization's expansion in the universe that Hart had estimated are very unrealistic. Hart didn't take into account that many factors could affect population growth. For example, the possibility that other civilizations might have a finite lifespan, or that a civilization might control population growth rates to maintain their ecology. This essentially means that a civilization might reach a type of equilibrium with their home planet based on its resources, and therefore would not need to venture out into the cosmos. Sagan and Newman asserted that a model of any given civilization would be vastly complicated and dependent on an umpteen amount of variables. Therefore, we cannot make assumptions based solely on the population models of humanity. Sagan and Newman went on to argue that just because we can't see alien life doesn't mean they don't exist. They just might not behave exactly in a way familiar to us. For example, perhaps another civilization has no interest in life outside their world, the same way humans do. Or perhaps advanced civilizations have a pact to allow life that emerges in the universe to evolve without influence, much like a real life Prime Directive from Star Trek. Whatever the reality, direct contact has yet to be a proven phenomenon. However, the latter half of the 20th century brought a wave of exploration into finding ways to detect extraterrestrial life. Even so, scientists have yet to find definitive proof of signs of life in the cosmos. Perhaps this is simply because our technology is not advanced enough. The radio and infrared signals we send out from Earth only stretch out to about 100 light years away before dissipating, which constitutes about 0.1% of the galaxy. Those signals are how alien life might be able to detect and locate us, the same way that we've attempted to detect alien life by looking for signals in outer space. But since we're only reaching 0.1% of the Milky Way, the rest of the universe might be completely blind to our existence. We're unable to reach much of the galaxy. And perhaps the same can be said for some distant lifeforms all the way at the other end of the Milky Way. This line of thinking supports something known as the Mediocrity principle, which is kind of everything. That is the exact opposite of the rare Earth hypothesis. The Mediocrity principle states that there is nothing unusual about our intelligence, our planet, our solar system, or our galaxy until evidence proves otherwise. And so, if we are to believe that there is nothing unusual about us, why wouldn't there be beings similar to us somewhere else in the universe? And if they are out there, what is preventing us from encountering them? Well, there are a few possibilities. Number one, that aliens couldn't and or can't reach Earth because of some sort of physical barrier. Number two, that aliens simply chose and actively choose not to visit Earth. And number three, that intelligent alien species just recently invented the technology to reach us, and they're still on their way. To which, I might add a fourth possibility. Maybe we'll call it the conspiracy theories destination equation, which is to say, if there is an alien life form on an alien planet, in order to search the universe for life, it would have to send out a ship in one direction all the way to the end of the universe, which means there would be an infinite number of tangential lines from that alien planet Every planet they hit. They would have to search for alien life. Meaning, since they don't know we're here and don't know to look for us, it could take an infinite amount of time to find us. Now, if one of these possibilities is the solution to the Fermi paradox, then we must turn our search outward. If alien life isn't coming to us, is there a way that we can find alien life? Life? The answer, anticlimactically, is maybe. In the second half of the 20th century, several efforts to find extraterrestrial life began. In the late 1960s and early 70s NASA participated in some efforts to search for extraterrestrial life with programs including Project Orion, the Microwave Observing Project, and the High Resolution Microwave Survey. These all used different forms of electromagnetic transmissions to try to detect alien life in outer space, but they found nothing conclusive. However, in 1981, Senator William Proxmire used Hart and Tipler's arguments to pull back funding for all of these projects. He said that if physicists argued that there was no extraterrestrial life at all, then what was the point of looking for it? It is a fair argument, but only if you take Michael Hart and Frank Tipler's arguments as gospel. Yet, like much of the work surrounding the Fermi Paradox, nothing can be for sure, because so much of it is based on conjecture. Despite the government shutting down their search for aliens, interest in extraterrestrial life did not. Wayne and others took up the mantle. The most prominent example was a private organization called the Search for Extraterrestrial intelligence, or the SETI Institute, and was founded in 1984 by Thomas Pearson and Jill Tarter in Mountain View, California. According to the institute, our mission is to explore, understand and explain the origin and nature of life in the universe and the evolution of intelligence. The researchers at SETI are fundamentally involved with the problem of the Fermi paradox. They are trying to discover at least a glimpse of extraterrestrial life, thereby altering our understanding of the universe. The SETI Institute utilizes physical and VI biological sciences, as well as astrophysics to make discoveries about life both on Earth and beyond. In outer space. Private endeavors like this solidified one simple fact. The public, scientists and non scientists alike, wanted to find aliens. And they were willing to go to great lengths to do so. In 1992, the US government's interest in alien life was sparked again. That year, NASA began the more official search for extraterrestrial intelligence, their very own SETI program. But less than one year later, this program was shuttered after a campaign against it led by Senator Richard Bryan. Even so, the SETI Institute blazes on. They continue to use state of the art technology to scan the night sky, looking for any sort of irregularity that might point to some sort of alien life. In their breadth of exploration, SETI may just have found the first signs of extraterrestrial intelligence. And with that discovery, we may not only have a possible answer to the Fermi paradox, but a much larger understanding of our place in the cosmos.
