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The planet we live on currently houses 7.1 billion people. Apart from our own species, there exists approximately 8.7 million other species, leading to a total of 3000 quintillion individual organisms alive at any given time. We can easily tell that earth is habitable, but, are we alone? Is earth the only source of life in the universe? Aside from conspiracies and the conventional green wobbly aliens with big black eyes, there really is a science behind the likelihood of extraterrestrial existence and where these organisms may exist in the universe. There are statistical challenges faced behind the potential existence of aliens as well as the methods currently in use to find evidence of extraterrestrial environments, and maybe even extraterrestrials themselves.
Statistically speaking, the universe is a huge place and astronomically speaking, the sun is a young star. There are billions of stars in the galaxy that are billions of years older. Because our sun has an orbiting planet capable of sustaining intelligent life, stars which are the sun’s age or older also have the capability of maintaining planets similar to earth, which implies there may be several more planets in the universe that could possibly hold intelligent life. Since the universe is billions of years old, these other worlds containing intelligent life could have started millions of years earlier than life on our earth, and because we are just now exploring the realm of interstellar travel, these other older civilizations could have fully developed methods to travel to, and completely colonize the planets of other stars in an entire galaxy. So, why haven’t we been contacted? This is a famous question posed as a result to the Fermi Paradox, which states the analogy I just explained.
One solution to this paradox may be explained in the Drake Equation. The Drake Equation predicts the statistical chances of life in the Milky Way Galaxy. An average of current estimations applied to this equation conclude that there are possibly 1000 to 100,000 civilizations ranging in intelligence in the Milky Way Galaxy. One caveat that comes with this equation, though, is that four of the variables, cannot be statistically estimated. Because of this, mathematical cosmologist Frank Tipler predicted a more pessimistic result to the Drake equation, a number much less than one civilization per galaxy. We could be the only civilization in our galaxy, which may explain the Fermi Paradox.
There are several other theories of why we have not been contacted by extraterrestrial life if it exists. Intelligent life could inevitably self-destruct before it has the capability of travelling interstellarly or extraterrestrials could as of now live in a way undetectable to humans.
Now, since we haven’t been visited, or even contacted, by any extraterrestrial life as we know it, the natural progression in determining if we are truly alone is to explore for ourselves; instead of waiting for other life to find us, we find other life. In order to find potential extraterrestrial environments, we need to narrow our search down to exclude the vacuum of space, and areas of extreme temperatures and high radiation, where life as we know it would never survive. This narrows the search down drastically, limiting the search to a specific type of planet or moon located in the habitable “goldilocks” zone, of a star’s planetary orbit range. This zone is derived from a mathematical calculation that determines how far a planet needs to be away from the sun in order to have liquid water reside on the surface. The hotter the star, the further away the habitable zone needs to be for the planet within this zone to carry liquid water. Where there is liquid water, there is a higher probability of existing life.
Because our current technology does not let us travel to other solar systems in a plausible amount of time to directly find these environments, we need to expand our methods of search to include much more than just sending rovers to potential life-carrying planets and moons. This is where we shift from the work done by NASA to an organization called the Search for Extraterrestrial Intelligence Institute, or SETI. SETI is the leading organization that searches for signs of life through large radio telescopes, possibly coming from other intelligent life. These telescopes continuously scan the sky and record all waves within a certain range coming from space. The data is then sifted through and determined if any abnormalities exist. An example of such abnormality can be seen in data retrieved in 1977, famously called the Wow! Signal. This signal was a strong, specific radio signal recorded by SETI telescopes. The signal has not been found again, and there is no concrete explanation for what could have caused this extremely specific radio wave, but if it did come from an extraterrestrial civilization, the signal would have required a 2.2-gigawatt transmitter, which is only capable of being constructed by a particularly advanced civilization.
So, we know the universe is big, and habitable environments astronomically rare. There is strong statistical evidence going in both ways, trying to answer the question of if we are truly alone. We haven’t been contacted by extraterrestrials and may never will be, but the nature of human curiosity has spawned searches, conspiracies, and entertainment for decades. As famous astrophysicist Niel deGrasse Tyson once said, “We are part of this universe; we are in this universe, but perhaps more important than both of those facts, is that the universe is in us.” We are all made from the elements found in the cores of stars, scattered throughout the universe, available to any reaction that sparks life. As living, functioning humans, it is hard to ignore this fact. We very well know we may not be the only ones in the universe, but why leave this up to thought? As long as we have the resources to look for other things out there, we will.
Statistically speaking, the universe is a huge place and astronomically speaking, the sun is a young star. There are billions of stars in the galaxy that are billions of years older. Because our sun has an orbiting planet capable of sustaining intelligent life, stars which are the sun’s age or older also have the capability of maintaining planets similar to earth, which implies there may be several more planets in the universe that could possibly hold intelligent life. Since the universe is billions of years old, these other worlds containing intelligent life could have started millions of years earlier than life on our earth, and because we are just now exploring the realm of interstellar travel, these other older civilizations could have fully developed methods to travel to, and completely colonize the planets of other stars in an entire galaxy. So, why haven’t we been contacted? This is a famous question posed as a result to the Fermi Paradox, which states the analogy I just explained.
One solution to this paradox may be explained in the Drake Equation. The Drake Equation predicts the statistical chances of life in the Milky Way Galaxy. An average of current estimations applied to this equation conclude that there are possibly 1000 to 100,000 civilizations ranging in intelligence in the Milky Way Galaxy. One caveat that comes with this equation, though, is that four of the variables, cannot be statistically estimated. Because of this, mathematical cosmologist Frank Tipler predicted a more pessimistic result to the Drake equation, a number much less than one civilization per galaxy. We could be the only civilization in our galaxy, which may explain the Fermi Paradox.
There are several other theories of why we have not been contacted by extraterrestrial life if it exists. Intelligent life could inevitably self-destruct before it has the capability of travelling interstellarly or extraterrestrials could as of now live in a way undetectable to humans.
Now, since we haven’t been visited, or even contacted, by any extraterrestrial life as we know it, the natural progression in determining if we are truly alone is to explore for ourselves; instead of waiting for other life to find us, we find other life. In order to find potential extraterrestrial environments, we need to narrow our search down to exclude the vacuum of space, and areas of extreme temperatures and high radiation, where life as we know it would never survive. This narrows the search down drastically, limiting the search to a specific type of planet or moon located in the habitable “goldilocks” zone, of a star’s planetary orbit range. This zone is derived from a mathematical calculation that determines how far a planet needs to be away from the sun in order to have liquid water reside on the surface. The hotter the star, the further away the habitable zone needs to be for the planet within this zone to carry liquid water. Where there is liquid water, there is a higher probability of existing life.
Because our current technology does not let us travel to other solar systems in a plausible amount of time to directly find these environments, we need to expand our methods of search to include much more than just sending rovers to potential life-carrying planets and moons. This is where we shift from the work done by NASA to an organization called the Search for Extraterrestrial Intelligence Institute, or SETI. SETI is the leading organization that searches for signs of life through large radio telescopes, possibly coming from other intelligent life. These telescopes continuously scan the sky and record all waves within a certain range coming from space. The data is then sifted through and determined if any abnormalities exist. An example of such abnormality can be seen in data retrieved in 1977, famously called the Wow! Signal. This signal was a strong, specific radio signal recorded by SETI telescopes. The signal has not been found again, and there is no concrete explanation for what could have caused this extremely specific radio wave, but if it did come from an extraterrestrial civilization, the signal would have required a 2.2-gigawatt transmitter, which is only capable of being constructed by a particularly advanced civilization.
So, we know the universe is big, and habitable environments astronomically rare. There is strong statistical evidence going in both ways, trying to answer the question of if we are truly alone. We haven’t been contacted by extraterrestrials and may never will be, but the nature of human curiosity has spawned searches, conspiracies, and entertainment for decades. As famous astrophysicist Niel deGrasse Tyson once said, “We are part of this universe; we are in this universe, but perhaps more important than both of those facts, is that the universe is in us.” We are all made from the elements found in the cores of stars, scattered throughout the universe, available to any reaction that sparks life. As living, functioning humans, it is hard to ignore this fact. We very well know we may not be the only ones in the universe, but why leave this up to thought? As long as we have the resources to look for other things out there, we will.