4 ms·

Without looking up the Drake Equation, here's a rough estimation of the problem. Ignoring all extinct species, there's an estimated 8.7 million unique species

Without looking up the Drake Equation, here's a rough estimation of the problem. Ignoring all extinct species, there's an estimated 8.7 million unique species of plants and animals currently on Earth. So let's do some dumb estimating and say that there's a one in 10 million chance of "intelligent" life evolving on a planet that supports life. (I will not address the controversial issue of whether or not human life is actually intelligent.) So whatever estimation is used for the number of habitable planets in our galaxy, Only 0.00001% of those planets might have intelligent life. Next, you must factor in how many of the intelligent species develop technology capable of interstellar communication, and when do they do it? Humans have existed for a few million years, but we have only had radio for a hundred years. With the development of technology comes the risk of self annihilation. We humans have had the ability to destroy ourselves for roughly 60 years. How much longer we go is anybody's guess, but given that life on our planet has existed for roughly 3.5 billion years, and the planet will become uninhabitable in another 5 billion (when the sun changes modes), the time window is pretty small. It's likely that life needs some elements that were less available in the early universe, so let's assume that it's only possible on planets of third-generation stars like ours. Also consider the speed-limit of EM propagation (C). There are only 76 stars within 100 light years of us. It's unlikely that intelligent life exists in any of those systems, but if it did, the inhabitants (if they were listening) would just now be able to hear us. Assuming we survive our technological revolution/evolution for another 100 years, we might get a message from a nearby system. Before then, we might receive some communications from systems farther away, but how long does a technological civilization use radio with simple modulation schemes that we would recognize as something other than noise? Maybe in less than a hundred years, we will have gone through radio, optical, and then quantum communications technology. It's likely that other technological civilizations (if they exist) are using communication technology that is incompatible with ours. I'm not sure if Drake considered all of these things, but it looks pretty bad for us with regard to our ability to confirm the existence of extraterrestrial intelligence any time soon.

Gupie 6y ago
> there's an estimated 8.7 million unique species of plants and animals currently on Earth. So [...] there's a one in 10 million chance of "intelligent" life evolving on a planet that supports life Isn't that the probability that a species is intelligent. The probability that intelligence will eventually evolve on a planet with life is 1.0, from the evidence that we have so far.
- anonymousiam 6y ago
  Sure, the probability is 1.0 given infinite time. It took 4.5 billion years for us to get here, and we didn't get started until 5 million years ago. That means Earth went through 99.89% of its existence with no intelligent life. Also, Earth has had numerous extinction events that killed off at least 3/4 of land-based life (and 96% of marine life). We have no way of knowing whether extinction events are more, or less common on other habitable planets, or whether such events might even be necessary for the evolution of intelligent life.
- Geminidog 6y ago
  This is a serious misunderstanding of probability. When someone won the lottery in the past he did not have a 100% chance of winning the lottery even though in hind sight he won. A person who has a 1 in a million chance to win the lottery CAN still win the lottery. And if he does win the lottery, his chances of winning was STILL one in a million. Same with life in the universe. Just because it happened does not make the probability of it happening at all 100%. Far from it.
  - Gupie 6y ago
    I was only joking when saying 100%, but it is high. It is like having a bag of 1000 marble and you put your hand in and pull out a green one. You now know that the probability that there are a lot of green marbles in the bag is high.
mcbits 6y ago
1/10 million species on Earth being intelligent doesn't really imply that 1/10 million planets with life would have intelligent life. Any planet with life undergoing evolution may also develop millions of species, with "intelligence" being an important trait for some of them. Problem is, that tells us nothing about how many planets could sprout life in the first place. Even right now on Earth, we have multiple tool-using species spanning mammals, birds, and cephalopods, separated by hundreds of millions of years of evolution. They all seem like good candidates for developing technology at some point over a few million years.
- iso947 6y ago
  In the billion or so years life has existed on earth, there’s no evidence any species built a nuclear bomb or had large plastic manufacturing or left anything in GEO, all of which we’ve achieved in the last 100 years. Progressing to that stage this seems unlikely for a planet with life on.
  - jjk166 6y ago
    It's not like every species rolls the dice independently to see if it will be an advanced civilization. That the smartest animal to ever live on this planet is alive right now is no less probable than the largest animal to ever live on this planet (the blue whale) is alive right now - both are products of evolutionary processes that took many millions of years and are continuing. In addition to increasing size, there is a trend in the fossil record of improving intelligence for species throughout the animal kingdom since the extinction of the dinosaurs, which themselves had undergone many millions of years of increasing complexity since the previous mass extinction. As for the sudden nature of humanity's major technological advances, that's just the nature of geometric growth - every advancement makes more advancements easier. The humans that took thousands of years to go from agriculture to writing were biologically no different from and no less capable than those who went from first flight of a plane to first walk on the moon in a single lifetime.
tasty_freeze 6y ago
> Humans have existed for a few million years, The most recent common ancestor with our primate cousins was about 7M years ago. There have been various hominid species, but I don't think we call them humans. I thought the general rough guess is homo sapiens are on the order of 200K-300K years old.

Gupie 6y ago

> there's an estimated 8.7 million unique species of plants and animals currently on Earth. So [...] there's a one in 10 million chance of "intelligent" life evolving on a planet that supports life Isn't that the probability that a species is intelligent. The probability that intelligence will eventually evolve on a planet with life is 1.0, from the evidence that we have so far.

anonymousiam 6y ago
Sure, the probability is 1.0 given infinite time. It took 4.5 billion years for us to get here, and we didn't get started until 5 million years ago. That means Earth went through 99.89% of its existence with no intelligent life. Also, Earth has had numerous extinction events that killed off at least 3/4 of land-based life (and 96% of marine life). We have no way of knowing whether extinction events are more, or less common on other habitable planets, or whether such events might even be necessary for the evolution of intelligent life.
Geminidog 6y ago
This is a serious misunderstanding of probability. When someone won the lottery in the past he did not have a 100% chance of winning the lottery even though in hind sight he won. A person who has a 1 in a million chance to win the lottery CAN still win the lottery. And if he does win the lottery, his chances of winning was STILL one in a million. Same with life in the universe. Just because it happened does not make the probability of it happening at all 100%. Far from it.
- Gupie 6y ago
  I was only joking when saying 100%, but it is high. It is like having a bag of 1000 marble and you put your hand in and pull out a green one. You now know that the probability that there are a lot of green marbles in the bag is high.

mcbits 6y ago

1/10 million species on Earth being intelligent doesn't really imply that 1/10 million planets with life would have intelligent life. Any planet with life undergoing evolution may also develop millions of species, with "intelligence" being an important trait for some of them. Problem is, that tells us nothing about how many planets could sprout life in the first place. Even right now on Earth, we have multiple tool-using species spanning mammals, birds, and cephalopods, separated by hundreds of millions of years of evolution. They all seem like good candidates for developing technology at some point over a few million years.

iso947 6y ago
In the billion or so years life has existed on earth, there’s no evidence any species built a nuclear bomb or had large plastic manufacturing or left anything in GEO, all of which we’ve achieved in the last 100 years. Progressing to that stage this seems unlikely for a planet with life on.
- jjk166 6y ago
  It's not like every species rolls the dice independently to see if it will be an advanced civilization. That the smartest animal to ever live on this planet is alive right now is no less probable than the largest animal to ever live on this planet (the blue whale) is alive right now - both are products of evolutionary processes that took many millions of years and are continuing. In addition to increasing size, there is a trend in the fossil record of improving intelligence for species throughout the animal kingdom since the extinction of the dinosaurs, which themselves had undergone many millions of years of increasing complexity since the previous mass extinction. As for the sudden nature of humanity's major technological advances, that's just the nature of geometric growth - every advancement makes more advancements easier. The humans that took thousands of years to go from agriculture to writing were biologically no different from and no less capable than those who went from first flight of a plane to first walk on the moon in a single lifetime.

tasty_freeze 6y ago

> Humans have existed for a few million years, The most recent common ancestor with our primate cousins was about 7M years ago. There have been various hominid species, but I don't think we call them humans. I thought the general rough guess is homo sapiens are on the order of 200K-300K years old.