Do you think any aliens exist in the universe?

[Kylie]

I think it's practically certain that alien life of some form exists elsewhere in the universe.

However, such life is most likely to be equivalent to single celled organisms or very primitive life.

I think multicellular life, that would be similar to plants or animals, would be much rarer.

And intelligent life far rarer still.

And life that is able to travel between the stars even rarer still.

And it's practically impossible that such life forms have come to Earth and done experiments on people.

 

[pood]

I think it's practically certain that alien life of some form exists elsewhere in the universe.

However, such life is most likely to be equivalent to single celled organisms or very primitive life.

I think multicellular life, that would be similar to plants or animals, would be much rarer.

And intelligent life far rarer still.

And life that is able to travel between the stars even rarer still.

And it's practically impossible that such life forms have come to Earth and done experiments on people.

I think you are probably right, but it it hard to quantify these claims. It remains possible that complex and intelligent life arose much earlier on other planets than on our own, and we are an outlier.

 

[bilby]

I think it's practically certain that alien life of some form exists elsewhere in the universe.

However, such life is most likely to be equivalent to single celled organisms or very primitive life.

I think multicellular life, that would be similar to plants or animals, would be much rarer.

And intelligent life far rarer still.

And life that is able to travel between the stars even rarer still.

And it's practically impossible that such life forms have come to Earth and done experiments on people.

I think you are probably right, but it it hard to quantify these claims. It remains possible that complex and intelligent life arose much earlier on other planets than on our own, and we are an outlier.

I'm with @Kylie on this one. Even on Earth, her heirarchy holds true - most life is unicellular and simple; Multicellular and/or intelligent life is far less common, though it's much easier for us to notice, 'cos a) it's big; And b) it's us.

Interstellar travel is still waaaaaay beyond our abilities, and is likely to remain so; Even our crazy billionaires who can afford to indulge a whim to promote spaceflight (which is very highly unprofitable, and seems destined to remain so for a loooooong time), limit their ambitions to visiting Mars, which is just next door, but is at the limit of our abilities; And the Moon, which is our own backyard.

And notably depite their desires, wealth, and efforts, they have yet to even get to the Moon.

The nearest star is in the order of 200,000 times as far away as Mars. The nearest star that has any chance of hosting Earthlike life is five or ten times as far again.

And all our space propulsion systems suffer from the fundamental laws of physics - the cost and difficulty of travelling to a distant location rises at least exponentially with distance.

My guess is that even if we were united as a species, with the goal of reaching an exoplanet as our sole priority, we still couldn't do it in the lifetime of our own star. And of course, the same applies to any aliens who might want to come here.

But if we could do it, why would we? Everywhere else is horrible. Mars is incredibly Earthlike as planets go, but is instantly lethal to pretty much all Earth life without massive engineering to protect against the hostile atmosphere, toxic soil, ionising radiation, and bitter cold. And that's the best part of the planet; a deep valley near the equator, in summer. The water (which we're gonna need) is all locked up at the poles.

If we wanted to live permanently on Mars, why don't any of us want to live permanently in Antarctica? Antarctica is an absolute paradise by comparison.

 

[pood]

I pretty much agree with all of this, especially the infeasibility of long-distance space travel. My point was just to remain somewhat agnostic on how swiftly complex life could evolve on another planet. It took billions of years to evolve here, but it is only one data point, and you can’t really generalize from one example. Maybe other planets are better suited to life, and complex life, than our own.

Then, too — and this is entirely speculative — maybe evolution as we understand it does not hold on other planets, and that organisms can develop in different and faster ways? Not long ago I posted about a scientific study suggesting that not all mutations are random with respect to environment, and may in fact occur in response to a changed environment. I have not seen any commentary on this study elsewhere online or in print, but if the study is true it suggests we may have some revisions to do in evolutionary theory.

 

[Kylie]

I think it's practically certain that alien life of some form exists elsewhere in the universe.

However, such life is most likely to be equivalent to single celled organisms or very primitive life.

I think multicellular life, that would be similar to plants or animals, would be much rarer.

And intelligent life far rarer still.

And life that is able to travel between the stars even rarer still.

And it's practically impossible that such life forms have come to Earth and done experiments on people.

I think you are probably right, but it it hard to quantify these claims. It remains possible that complex and intelligent life arose much earlier on other planets than on our own, and we are an outlier.

Perhaps. After all, it's possible that some dinosaur species could have become a species as intelligent as us if it wasn't for a certain asteroid.

Still, we can't assume that Earth is something special that has had set back after set back more often than any other planet where life could have evolved.

 

[Kylie]

I pretty much agree with all of this, especially the infeasibility of long-distance space travel. My point was just to remain somewhat agnostic on how swiftly complex life could evolve on another planet. It took billions of years to evolve here, but it is only one data point, and you can’t really generalize from one example. Maybe other planets are better suited to life, and complex life, than our own.

How would this work? Planets are not better suited for life, life becomes better suited to the planets. That's how evolution works.

Then, too — and this is entirely speculative — maybe evolution as we understand it does not hold on other planets, and that organisms can develop in different and faster ways? Not long ago I posted about a scientific study suggesting that not all mutations are random with respect to environment, and may in fact occur in response to a changed environment. I have not seen any commentary on this study elsewhere online or in print, but if the study is true it suggests we may have some revisions to do in evolutionary theory.

Why would the principles of evolution not work on other planets the same way they work here?

Random mutations produce a variety of different traits. Those traits that increase the likelihood of reproduction are going to get passed down to offsrping. Those traits that decrease the likelihood of reproduction are going to die out.

Why would that be any different on other planets?

Also, if we're going to suggest that somehow the rate of evolution is different on different planets, then it's just as likely that Earth is the planet that has the fastest rate of evolution.

 

[pood]

I pretty much agree with all of this, especially the infeasibility of long-distance space travel. My point was just to remain somewhat agnostic on how swiftly complex life could evolve on another planet. It took billions of years to evolve here, but it is only one data point, and you can’t really generalize from one example. Maybe other planets are better suited to life, and complex life, than our own.

How would this work? Planets are not better suited for life, life becomes better suited to the planets. That's how evolution works.

Then, too — and this is entirely speculative — maybe evolution as we understand it does not hold on other planets, and that organisms can develop in different and faster ways? Not long ago I posted about a scientific study suggesting that not all mutations are random with respect to environment, and may in fact occur in response to a changed environment. I have not seen any commentary on this study elsewhere online or in print, but if the study is true it suggests we may have some revisions to do in evolutionary theory.

Why would the principles of evolution not work on other planets the same way they work here?

Random mutations produce a variety of different traits. Those traits that increase the likelihood of reproduction are going to get passed down to offsrping. Those traits that decrease the likelihood of reproduction are going to die out.

Why would that be any different on other planets?

Also, if we're going to suggest that somehow the rate of evolution is different on different planets, then it's just as likely that Earth is the planet that has the fastest rate of evolution.

Sure, I agree with all this, but — we have one data point. Earth. We really don’t know if the principles of evolution would work the same on other planets. As noted, I posted a science article recently that questions whether even here on earth, all mutations are random with respect to the environment. I can envision a set of circumstances in which, say, Lamarckism holds, or something we have never considered.

And yes, it’s possible that earth has the fastest rate of evolution. It could also be the slowest. We just don’t know and cannot estimate any probabilities. That is the problem with having only one example to study.

 

[bilby]

After all, it's possible that some dinosaur species could have become a species as intelligent as us if it wasn't for a certain asteroid.

It's possible that they did.

Archaeologists have trouble finding evidence of human activity just a few thousand years ago. A dinosaur civilisation with a similar technology level to that of ancient Greece, Rome, Egypt or Mesopotamia could easily have been erased entirely from the geological record in seventy million years; It's quite possible that in another seventy million, Egypt will have subducted into the mantle, leaving no trace even of the pyramids.

Certainly their surviving relatives include highly intelligent species - all of whom have very small brains by comparison to similarly intelligent mammals. So even the evidence of small skull capacity amongst surviving fossils may not soeak against intelligence - and of course there are many dinosaur species for whom no fossils (much less fossil skulls) exist.

 

[pood]

After all, it's possible that some dinosaur species could have become a species as intelligent as us if it wasn't for a certain asteroid.

It's possible that they did.

Archaeologists have trouble finding evidence of human activity just a few thousand years ago. A dinosaur civilisation with a similar technology level to that of ancient Greece, Rome, Egypt or Mesopotamia could easily have been erased entirely from the geological record in seventy million years; It's quite possible that in another seventy million, Egypt will have subducted into the mantle, leaving no trace even of the pyramids.

Certainly their surviving relatives include highly intelligent species - all of whom have very small brains by comparison to similarly intelligent mammals. So even the evidence of small skull capacity amongst surviving fossils may not soeak against intelligence - and of course there are many dinosaur species for whom no fossils (much less fossil skulls) exist.

There is a New Scientist article (not a good source) that addresses this.

An Arthur C. Clarke short story I read many years ago deals with the question of aliens arriving at a dead earth many millions of years in the future and finding evidence of a past civilization based on film or videos of Mickey Mouse or something like that. I believe they concluded that intelligent earthlings were cartoon-like mice. Can’t swear to that specifically but can’t be arsed to try to look it up now. That was the general gist of the story, though.

 

[Kylie]

I pretty much agree with all of this, especially the infeasibility of long-distance space travel. My point was just to remain somewhat agnostic on how swiftly complex life could evolve on another planet. It took billions of years to evolve here, but it is only one data point, and you can’t really generalize from one example. Maybe other planets are better suited to life, and complex life, than our own.

How would this work? Planets are not better suited for life, life becomes better suited to the planets. That's how evolution works.

Then, too — and this is entirely speculative — maybe evolution as we understand it does not hold on other planets, and that organisms can develop in different and faster ways? Not long ago I posted about a scientific study suggesting that not all mutations are random with respect to environment, and may in fact occur in response to a changed environment. I have not seen any commentary on this study elsewhere online or in print, but if the study is true it suggests we may have some revisions to do in evolutionary theory.

Why would the principles of evolution not work on other planets the same way they work here?

Random mutations produce a variety of different traits. Those traits that increase the likelihood of reproduction are going to get passed down to offsrping. Those traits that decrease the likelihood of reproduction are going to die out.

Why would that be any different on other planets?

Also, if we're going to suggest that somehow the rate of evolution is different on different planets, then it's just as likely that Earth is the planet that has the fastest rate of evolution.

Sure, I agree with all this, but — we have one data point. Earth. We really don’t know if the principles of evolution would work the same on other planets. As noted, I posted a science article recently that questions whether even here on earth, all mutations are random with respect to the environment. I can envision a set of circumstances in which, say, Lamarckism holds, or something we have never considered.

Why would natural selection stop working as an evolutionary mechanism?

How could Lamarckian evolution work?

And yes, it’s possible that earth has the fastest rate of evolution. It could also be the slowest. We just don’t know and cannot estimate any probabilities. That is the problem with having only one example to study.

So, let's go with the "earth is nothing special" idea and work under the assumption that things will work on other planets much as they do here.

After all, we have no reason to believe that gravity is different on other planets, so why evolution?

We know that evolution can work the way it is here. We also have no reason to believe that it should work differently on other planets. So until we get such a reason, there's no reason to think that it would work differently on other planets.

 

[pood]

I pretty much agree with all of this, especially the infeasibility of long-distance space travel. My point was just to remain somewhat agnostic on how swiftly complex life could evolve on another planet. It took billions of years to evolve here, but it is only one data point, and you can’t really generalize from one example. Maybe other planets are better suited to life, and complex life, than our own.

How would this work? Planets are not better suited for life, life becomes better suited to the planets. That's how evolution works.

Then, too — and this is entirely speculative — maybe evolution as we understand it does not hold on other planets, and that organisms can develop in different and faster ways? Not long ago I posted about a scientific study suggesting that not all mutations are random with respect to environment, and may in fact occur in response to a changed environment. I have not seen any commentary on this study elsewhere online or in print, but if the study is true it suggests we may have some revisions to do in evolutionary theory.

Why would the principles of evolution not work on other planets the same way they work here?

Random mutations produce a variety of different traits. Those traits that increase the likelihood of reproduction are going to get passed down to offsrping. Those traits that decrease the likelihood of reproduction are going to die out.

Why would that be any different on other planets?

Also, if we're going to suggest that somehow the rate of evolution is different on different planets, then it's just as likely that Earth is the planet that has the fastest rate of evolution.

Sure, I agree with all this, but — we have one data point. Earth. We really don’t know if the principles of evolution would work the same on other planets. As noted, I posted a science article recently that questions whether even here on earth, all mutations are random with respect to the environment. I can envision a set of circumstances in which, say, Lamarckism holds, or something we have never considered.

Why would natural selection stop working as an evolutionary mechanism?

How could Lamarckian evolution work?

And yes, it’s possible that earth has the fastest rate of evolution. It could also be the slowest. We just don’t know and cannot estimate any probabilities. That is the problem with having only one example to study.

So, let's go with the "earth is nothing special" idea and work under the assumption that things will work on other planets much as they do here.

After all, we have no reason to believe that gravity is different on other planets, so why evolution?

We know that evolution can work the way it is here. We also have no reason to believe that it should work differently on other planets. So until we get such a reason, there's no reason to think that it would work differently on other planets.

I am not exactly contesting what you are saying. I think you are probably right. I am pointing out, however, that we can observe gravity to be universal, because we have vast amounts of data that confirm this.

But we cannot observe evolution to be universal or other life forms to exist or that they develop in the same way that we do, because we have only one data point, which is earth. Evolution on another planet is an assumption. I think it is probably a good assumption but it remains defeasible.

 

[Kylie]

After all, it's possible that some dinosaur species could have become a species as intelligent as us if it wasn't for a certain asteroid.

It's possible that they did.

Archaeologists have trouble finding evidence of human activity just a few thousand years ago. A dinosaur civilisation with a similar technology level to that of ancient Greece, Rome, Egypt or Mesopotamia could easily have been erased entirely from the geological record in seventy million years; It's quite possible that in another seventy million, Egypt will have subducted into the mantle, leaving no trace even of the pyramids.

Certainly their surviving relatives include highly intelligent species - all of whom have very small brains by comparison to similarly intelligent mammals. So even the evidence of small skull capacity amongst surviving fossils may not soeak against intelligence - and of course there are many dinosaur species for whom no fossils (much less fossil skulls) exist.

True. But I think that's highly unlikely.

For one thing, there is one thing that we have that we are absolutely certain of that comes from that long ago: their fossils.

Let's assume that there was a Dinosaur society with a technological level about the same as the ancient Romans. They had a wide trade network, so they spread out over a large area.

We'd have to assume that the dinosaur society would have done the same. And since such societies can leave traces on skeletons (for example, signs of broken femurs that have healed, a wound that is fatal without treatment), surely we would see indications of similar things. Yes, we have dinosaur fossils with evidence of healed injuries, but nothing (as far as I am aware) of an injury that would be fatal without medical treatment. We'd also surely see fossil dinosaurs that show evidence of having been buried in a ritualistic way, with bodies arranged in a specific way, and with artifacts, such as shells or bone tools. And yet we don't see this. And we know that things like bones and shells can survive for those millions of years.

Now, of course, this doesn't prove that it is impossible that dinosaurs developed such a society, but it does, I think, serve as strong evidence against it.

 

[Kylie]

I pretty much agree with all of this, especially the infeasibility of long-distance space travel. My point was just to remain somewhat agnostic on how swiftly complex life could evolve on another planet. It took billions of years to evolve here, but it is only one data point, and you can’t really generalize from one example. Maybe other planets are better suited to life, and complex life, than our own.

How would this work? Planets are not better suited for life, life becomes better suited to the planets. That's how evolution works.

Then, too — and this is entirely speculative — maybe evolution as we understand it does not hold on other planets, and that organisms can develop in different and faster ways? Not long ago I posted about a scientific study suggesting that not all mutations are random with respect to environment, and may in fact occur in response to a changed environment. I have not seen any commentary on this study elsewhere online or in print, but if the study is true it suggests we may have some revisions to do in evolutionary theory.

Why would the principles of evolution not work on other planets the same way they work here?

Random mutations produce a variety of different traits. Those traits that increase the likelihood of reproduction are going to get passed down to offsrping. Those traits that decrease the likelihood of reproduction are going to die out.

Why would that be any different on other planets?

Also, if we're going to suggest that somehow the rate of evolution is different on different planets, then it's just as likely that Earth is the planet that has the fastest rate of evolution.

Sure, I agree with all this, but — we have one data point. Earth. We really don’t know if the principles of evolution would work the same on other planets. As noted, I posted a science article recently that questions whether even here on earth, all mutations are random with respect to the environment. I can envision a set of circumstances in which, say, Lamarckism holds, or something we have never considered.

Why would natural selection stop working as an evolutionary mechanism?

How could Lamarckian evolution work?

And yes, it’s possible that earth has the fastest rate of evolution. It could also be the slowest. We just don’t know and cannot estimate any probabilities. That is the problem with having only one example to study.

So, let's go with the "earth is nothing special" idea and work under the assumption that things will work on other planets much as they do here.

After all, we have no reason to believe that gravity is different on other planets, so why evolution?

We know that evolution can work the way it is here. We also have no reason to believe that it should work differently on other planets. So until we get such a reason, there's no reason to think that it would work differently on other planets.

I am not exactly contesting what you are saying. I think you are probably right. I am pointing out, however, that we can observe gravity to be universal, because we have vast amounts of data that confirm this.

But we cannot observe evolution to be universal or other life forms to exist or that they develop in the same way that we do, because we have only one data point, which is earth. Evolution on another planet is an assumption. I think it is probably a good assumption but it remains defeasible.

Can you propose any mechanism which would prevent evolution happening on another planet the way it does on Earth?

 

[pood]

Can you propose any mechanism which would prevent evolution happening on another planet the way it does on Earth?

I am not proposing anything. I am saying we should remain agnostic on the matter.

We have one data point, life on earth. Even here, we do not fully understand the origin and development of life. We do not know how life began. As noted in a science paper, it may even be the case that some mutations are not random with respect to the environment, but may occur in response to the environment. If that were true, it would require a significant revision to evolutionary theory.

I don’t know. I know nothing about life on other worlds, or even if it exists. I suspect it does. If it does, I do not know how it develops, because it remains possible that evolution, as we understand it, is not universal. My point is that while we can observe gravity to be universal, we cannot do the same for evolution or life.

 

[Kylie]

Can you propose any mechanism which would prevent evolution happening on another planet the way it does on Earth?

I am not proposing anything. I am saying we should remain agnostic on the matter.

We have one data point, life on earth. Even here, we do not fully understand the origin and development of life. We do not know how life began. As noted in a science paper, it may even be the case that some mutations are not random with respect to the environment, but may occur in response to the environment. If that were true, it would require a significant revision to evolutionary theory.

I don’t know. I know nothing about life on other worlds, or even if it exists. I suspect it does. If it does, I do not know how it develops, because it remains possible that evolution, as we understand it, is not universal. My point is that while we can observe gravity to be universal, we cannot do the same for evolution or life.

You are missing my point.

We KNOW evolution works here.

You are suggesting that we be open to the idea that it doesn't work somewhere else, despite there being no evidence for it not working differently.

That's like saying that even though my toaster works by using electricity to heat wire elements to cook the bread, it doesn't prove that ALL toasters work that way, and so we should be agnostic about the idea that maybe there are toast fairies that make toast in other countries.

Do you see how ridiculous that is?

 

[pood]

Suppose I toss a die one time and it comes up three. How do know it won’t come up three every time? To determine if there is a probability distribution for the die, I would have to toss it many times to reasonably determine that the probability of it coming up three is one in six. I have no way of determining what the probability of life on other worlds is or how it would arise or evolve, if indeed it does evolve. Maybe we are unique. Maybe there are other life forms but we are an outlier on how we develop. Maybe there are worlds so much better suited to life that complex organisms arise quickly, through what we understand to be evolution or through other means. Who knows?

I certainly don’t.

 

[steve_bank]

It is not just evolution.

It is all the processes led to environment that allowed the first self replicating structures to form.

The demise of the dinosaurs.

The Moon factors into it.

The Moon is crucial for stabilizing Earth's axial tilt (currently ~23.5°), preventing extreme wobbles that would cause chaotic, drastic seasonal shifts and unpredictable climates
, making life as we know it possible. Its gravitational pull acts like a stabilizer, counteracting the gravitational nudges from other planets, leading to stable, predictable seasons, while also slowing Earth's rotation and affecting tides.

We as humanoids wit technology may be rare or even unique.

 

[pood]

Can you propose any mechanism which would prevent evolution happening on another planet the way it does on Earth?

I am not proposing anything. I am saying we should remain agnostic on the matter.

We have one data point, life on earth. Even here, we do not fully understand the origin and development of life. We do not know how life began. As noted in a science paper, it may even be the case that some mutations are not random with respect to the environment, but may occur in response to the environment. If that were true, it would require a significant revision to evolutionary theory.

I don’t know. I know nothing about life on other worlds, or even if it exists. I suspect it does. If it does, I do not know how it develops, because it remains possible that evolution, as we understand it, is not universal. My point is that while we can observe gravity to be universal, we cannot do the same for evolution or life.

You are missing my point.

We KNOW evolution works here.

You are suggesting that we be open to the idea that it doesn't work somewhere else, despite there being no evidence for it not working differently.

That's like saying that even though my toaster works by using electricity to heat wire elements to cook the bread, it doesn't prove that ALL toasters work that way, and so we should be agnostic about the idea that maybe there are toast fairies that make toast in other countries.

Do you see how ridiculous that is?

Yes, we know evolution works here, but there is dispute over how it works. There are debates over how much influence natural selection vs. genetic drift has. As mentioned, we now have a scientific study that suggests not all mutations are random with respect to the environment.

I can imagine worlds in which Lamarckism holds or something else we cannot even imagine. I can imagine no world at which gravity fails to hold because of empiricism, but I can imagine logically possible worlds at which gravity fails to hold.

 

[pood]

To declare that evolution is universal in the same way that gravity is, is an unfounded assumption. We can see that gravity works everywhere and at all times. We have only one example of life, here on earth, and there is no way to extrapolate that it is universal among all life forms, even if other life forms exist at all. We don’t know.

Which is why I identify as an agnostic. I don’t know all sorts of shit.

 

[pood]

How do we know that the “laws” of physics are laws at all? I don’t think they are. I think they are descriptions of what happens in the world meditated by our particular perceptual and cognitive structures.

Aliens with radically different perceptual and cognitive structures might come up with different “laws” and even maths.

Who knows?

I sure don’t.