Apr 24, 2024 05:39 PM
https://bigthink.com/starts-with-a-bang/...nt-aliens/
KEY POINTS: Long ago, Enrico Fermi posed a simple question just by gazing at the stars: "Where is everybody?" Known today as the Fermi Paradox, there are many possible solutions, but some explanations are far simpler than others: namely, that there isn't anyone else. Still, the most common way of estimating who's out there, the Drake equation, should never be used. Here's the science of how to do it right.
EXCERPTS: The Drake equation is one way to arrive at an estimate of the number of spacefaring, technologically advanced civilizations in the galaxy or Universe today. However, it relies on a number of assumptions that are not necessarily very good, and contains many unknowns that we lack the necessary information to provide meaningful estimates for.
[...] But that’s only the superficial reason why the Drake equation is problematic today. The deeper reason is that the Drake equation, when it was put forth, made an assumption about the Universe that we now know is untrue: It assumed that the Universe was eternal and static in time. As we learned only a few years after Frank Drake first proposed his equation, the Universe doesn’t exist in a steady state, where it’s unchanging in time, but rather has evolved from a hot, dense, energetic, and rapidly expanding state: a hot Big Bang that occurred over a finite duration in our cosmic past.
Instead, a much more productive route is to calculate the quantities we now can speak about with some level of certainty, and then move on to the great cosmic unknowns in as responsible a fashion as we can. Unlike the situation some 60 years ago, when the Drake equation was first proposed, we now have an excellent idea of what our Universe is like, both in and beyond the Milky Way and the Local Group...
[...] We’ve also learned a lot about the types and abundances of planets that exist around stars other than our own: exoplanets. [...] Instead of needing to speculate about how many stars form, how many have planets, how many planets per system have the potential for life, etc., we can actually utilize some excellent data...
[...] At this point, our uncertainties are so large that it’s eminently reasonable that not only might human beings be the only intelligent life in the Milky Way, but in the entire observable Universe, which likely contains more than a trillion (1,000,000,000,000) times as many stars as our own galaxy...
[...] We can confidently say, give or take, that there are perhaps 20 billion Earth-sized planets, made of similar elements to our own world, at the right distance from their parent star to have liquid water on their surface, assuming an Earth-like atmosphere as well. But of those worlds, how many of them have life? It could be most of them, many of them, or only a tiny fraction. Of the ones with life, how many of them develop complex, differentiated, intelligent, and technologically advanced life?
Before we even start asking questions about longevity, colonization, or machine-based life, we should admit — with a non-negligible probability — the most obvious resolution to the Fermi Paradox: The reason we haven’t made first contact with intelligent, technologically advanced, and spacefaring alien civilizations is because there are none. In all the galaxy, and perhaps even in all the Universe, we really may be alone... (MORE - missing details)
KEY POINTS: Long ago, Enrico Fermi posed a simple question just by gazing at the stars: "Where is everybody?" Known today as the Fermi Paradox, there are many possible solutions, but some explanations are far simpler than others: namely, that there isn't anyone else. Still, the most common way of estimating who's out there, the Drake equation, should never be used. Here's the science of how to do it right.
EXCERPTS: The Drake equation is one way to arrive at an estimate of the number of spacefaring, technologically advanced civilizations in the galaxy or Universe today. However, it relies on a number of assumptions that are not necessarily very good, and contains many unknowns that we lack the necessary information to provide meaningful estimates for.
[...] But that’s only the superficial reason why the Drake equation is problematic today. The deeper reason is that the Drake equation, when it was put forth, made an assumption about the Universe that we now know is untrue: It assumed that the Universe was eternal and static in time. As we learned only a few years after Frank Drake first proposed his equation, the Universe doesn’t exist in a steady state, where it’s unchanging in time, but rather has evolved from a hot, dense, energetic, and rapidly expanding state: a hot Big Bang that occurred over a finite duration in our cosmic past.
Instead, a much more productive route is to calculate the quantities we now can speak about with some level of certainty, and then move on to the great cosmic unknowns in as responsible a fashion as we can. Unlike the situation some 60 years ago, when the Drake equation was first proposed, we now have an excellent idea of what our Universe is like, both in and beyond the Milky Way and the Local Group...
[...] We’ve also learned a lot about the types and abundances of planets that exist around stars other than our own: exoplanets. [...] Instead of needing to speculate about how many stars form, how many have planets, how many planets per system have the potential for life, etc., we can actually utilize some excellent data...
[...] At this point, our uncertainties are so large that it’s eminently reasonable that not only might human beings be the only intelligent life in the Milky Way, but in the entire observable Universe, which likely contains more than a trillion (1,000,000,000,000) times as many stars as our own galaxy...
[...] We can confidently say, give or take, that there are perhaps 20 billion Earth-sized planets, made of similar elements to our own world, at the right distance from their parent star to have liquid water on their surface, assuming an Earth-like atmosphere as well. But of those worlds, how many of them have life? It could be most of them, many of them, or only a tiny fraction. Of the ones with life, how many of them develop complex, differentiated, intelligent, and technologically advanced life?
Before we even start asking questions about longevity, colonization, or machine-based life, we should admit — with a non-negligible probability — the most obvious resolution to the Fermi Paradox: The reason we haven’t made first contact with intelligent, technologically advanced, and spacefaring alien civilizations is because there are none. In all the galaxy, and perhaps even in all the Universe, we really may be alone... (MORE - missing details)
