Are You There, Aliens? It’s Us, the Human Race
“I bet everyone here a cup of coffee that we’ll find aliens within two dozen years.”
– Dr. Seth Shostak, Director of Communications for SETI
Look up into a clear night sky in a city, and you might see a small handful of pinpricks of light dotting the sky. Move out to the suburbs, where there’s less in the way of light pollution, and you’ll see a few more. Keep traveling away from population and artificial light – down a deserted highway, or out into a dark forest – and the sky begins to explode with thousands of stars, each of which could have their own solar system. Even then, the stars we see in the darkest of night skies still are only a small fraction of the stars in our galaxy, and our …show more content…
Does that simply mean they’re not out there at all? Fermi’s paradox would argue that’s exactly what it means. The Fermi paradox argues that if the universe is billions of years old, then there should be civilizations far more advanced than ours colonizing the galaxy; since we see no evidence of that, we must be alone (Webb, 2). Drake’s equation, while slightly more optimistic, still reduces the probability of communicating with other intelligent life to near zero: multiply the number of stars by the fraction of those with solar systems, then again by the fraction of habitable planets, then again by the fraction of those that developed life, then again by the fraction of those that evolved to intelligent life, and then one last time by the fraction that may then be capable of interstellar travel or communication (Tyson, 209). Neither of these propositions are very promising if one is asking about the presence of intelligent …show more content…
One is their limited scope. Currently, habitable zones are defined solely by distance from a star, but there are other factors that could determine whether or not a planet could hold liquid water. Venus, the hottest planet in the solar system, actually falls within the Sun’s habitable zone; Mars, which falls well outside the habitable zone, has substantial evidence (in the form of dry riverbeds and floodplains) that there was once liquid water on its surface (Tyson, 210). The difference between the two is atmosphere. Venus has a thick carbon dioxide atmosphere that prevents almost all of the incoming solar radiation from leaving again (Tyson, 210). It’s the same greenhouse effect Earth has, only turned up to eleven. Meanwhile Mars’s atmosphere, which is also mostly carbon dioxide, is extremely thin: 100 times thinner than Earth’s atmosphere (Sharp). Researchers from Caltech believe that, in the past, Mars had a thicker atmosphere with a better greenhouse effect, allowing for liquid surface water despite its distance from the sun (Redd). This atmosphere was lost over time, leaving Mars’s surface a frozen, inhospitable wasteland where once there could’ve been the possibility of water, and therefore, of
“I bet everyone here a cup of coffee that we’ll find aliens within two dozen years.”
– Dr. Seth Shostak, Director of Communications for SETI
Look up into a clear night sky in a city, and you might see a small handful of pinpricks of light dotting the sky. Move out to the suburbs, where there’s less in the way of light pollution, and you’ll see a few more. Keep traveling away from population and artificial light – down a deserted highway, or out into a dark forest – and the sky begins to explode with thousands of stars, each of which could have their own solar system. Even then, the stars we see in the darkest of night skies still are only a small fraction of the stars in our galaxy, and our …show more content…
Does that simply mean they’re not out there at all? Fermi’s paradox would argue that’s exactly what it means. The Fermi paradox argues that if the universe is billions of years old, then there should be civilizations far more advanced than ours colonizing the galaxy; since we see no evidence of that, we must be alone (Webb, 2). Drake’s equation, while slightly more optimistic, still reduces the probability of communicating with other intelligent life to near zero: multiply the number of stars by the fraction of those with solar systems, then again by the fraction of habitable planets, then again by the fraction of those that developed life, then again by the fraction of those that evolved to intelligent life, and then one last time by the fraction that may then be capable of interstellar travel or communication (Tyson, 209). Neither of these propositions are very promising if one is asking about the presence of intelligent …show more content…
One is their limited scope. Currently, habitable zones are defined solely by distance from a star, but there are other factors that could determine whether or not a planet could hold liquid water. Venus, the hottest planet in the solar system, actually falls within the Sun’s habitable zone; Mars, which falls well outside the habitable zone, has substantial evidence (in the form of dry riverbeds and floodplains) that there was once liquid water on its surface (Tyson, 210). The difference between the two is atmosphere. Venus has a thick carbon dioxide atmosphere that prevents almost all of the incoming solar radiation from leaving again (Tyson, 210). It’s the same greenhouse effect Earth has, only turned up to eleven. Meanwhile Mars’s atmosphere, which is also mostly carbon dioxide, is extremely thin: 100 times thinner than Earth’s atmosphere (Sharp). Researchers from Caltech believe that, in the past, Mars had a thicker atmosphere with a better greenhouse effect, allowing for liquid surface water despite its distance from the sun (Redd). This atmosphere was lost over time, leaving Mars’s surface a frozen, inhospitable wasteland where once there could’ve been the possibility of water, and therefore, of