It would seem to me one of the most important requirements are planets with liquid, vapor, solid water cycles with liquid water, land boundary interfaces. Under these conditions life should be present from what we understand about the evolution of life on earth. If we assume that our tiny solar system is typical for this generation of stars (nothing says otherwise) there are billions and billions of possible sites for intelligent life outside of our solar system.

I don't see why intelligent life couldn't evolve entirely in/under the water (i.e., even on a planet that has no land masses at all).

 

I don't see why intelligent life couldn't evolve entirely in/under the water (i.e., even on a planet that has no land masses at all).

The problem IMO with water worlds is the lack of complex molecule building in the presence of normal atmosphere. That water/land boundary can cause great biodiversity and evolution to use diverse energy sources. A water world with a wet/wet energy boundary "sweet spot" is completely possible but the odds for complex life IMO are much greater where UV and other mutation driving forces are present over wide areas.

 

It would seem to me one of the most important requirements are planets with liquid, vapor, solid water cycles with liquid water, land boundary interfaces. Under these conditions life should be present from what we understand about the evolution of life on earth. If we assume that our tiny solar system is typical for this generation of stars (nothing says otherwise) there are billions and billions of possible sites for intelligent life outside of our solar system.

A stable and consistent rotation rotation of the planet is also important. As is the planet's orbital path. Doen't do much good if the planet is frozen half of the year.

 

The problem IMO with water worlds is the lack of complex molecule building in the presence of normal atmosphere. That water/land boundary can cause great biodiversity and evolution to use diverse energy sources. A water world with a wet/wet energy boundary "sweet spot" is completely possible but the odds for complex life IMO are much greater where UV and other mutation driving forces are present over wide areas.

Water also has challenges for the beings evolving in the water to manipulate their enviroment. Part of the success of humans is our arms. legs and most important the opposable thumb.

Whales and dolphins are highly intelligent creatures as well as a number of land based animals. You have to wonder how more advanced they would be if they were able to have the same advantage of learning from manipulation of the enviroment like we have done over the eons.

I would agree that intelligent under water life is possible but it likely once was land based.

 

A stable and consistent rotation rotation of the planet is also important. As is the planet's orbital path. Doen't do much good if the planet is frozen half of the year.

That might make things a bit more difficult to get going but evolved life forms can handle Antarctic winters if there is energy storage of some type.

 

You are thinking like a human who is inherently ethnocentric and indelibly prone to anthropomorphism. As we all are. Adaptation to the environment is either accomplished or you die making room for those still living who can and must adapt.

 

Considering that current estimates place the number of stars in the milky way at around 400 billion, I'd say that applying the brute force of statistics to the problem would yield that there must be a significant number of planets with earth-like conditions in this galaxy alone.

The real problem is that we do not yet have enough information to perform a reasonable calculation, since the amount of earth-like planets that we know of is exactly one.

But, as the main character in Carl Sagan's novel "Contact" once said: if there weren't any other life out there but us, it would be a awful waste of space.

 

That might make things a bit more difficult to get going but evolved life forms can handle Antarctic winters if there is energy storage of some type.

I am referring to human intelligence or better. Certainly there are creatures that can live in extremely cold environment. The mentioned whales for one, but they simply don't posses the intelligence of humans. OK most humans. As I am sure a whale or even a seal is probably more intelligent than a vast number of humans.

 

You are thinking like a human who is inherently ethnocentric and indelibly prone to anthropomorphism. As we all are. Adaptation to the environment is either accomplished or you die making room for those still living who can and must adapt.

I believe that 'human' like (I know, what exactly does human mean) characteristics are common in this universe on earth like planets. Our evolution of basic mechanical features, characteristics and tool creation/usage are unlikely to be special due to how ordinary our solar system is and the common physics of mechanical advantage across this universe. The actual structures might be very difference but the toolkit need for advanced mechanical intelligence should be much the same.

 

Considering that current estimates place the number of stars in the milky way at around 400 billion, I'd say that applying the brute force of statistics to the problem would yield that there must be a significant number of planets with earth-like conditions in this galaxy alone.

The real problem is that we do not yet have enough information to perform a reasonable calculation, since the amount of earth-like planets that we know of is exactly one.

But, as the main character in Carl Sagan's novel "Contact" once said: if there weren't any other life out there but us, it would be a awful waste of space.

It is not the number of planets that is the problem. It is a planet that exists in an almost ideal conditions as does the earth.

Geologically stable is yet another important factor that earth possesses. The earth of a few billion years ago would have never allowed human level intelligent life to evolve even if life was given more time to evolve. Earth was simply too geologically unstable to allow life to evolve to any significant degree. Had the earth not stabilized none of us would exist and we certainly would nut be typing on these computers.

 

It is not the number of planets that is the problem. It is a planet that exists in an almost ideal conditions as does the earth.

Geologically stable is yet another important factor that earth possesses. The earth of a few billion years ago would have never allowed human level intelligent life to evolve even if life was given more time to evolve. Earth was simply too geologically unstable to allow life to evolve to any significant degree. Had the earth not stabilized none of us would exist and we certainly would nut be typing on these computers.

I would expect there to be several planets in the orbital Goldilocks zone on huge numbers of stars with multiple orbiting planets on our ‘Galactic Habitable Zone’. There are really two in ours but only one has the proper conditions for present life while Mars might have been livable in the distant past by earth standards. It could be that life transforms the conditions on the planet to be more hospitable to evolving life if the initial conditions are viable and stable for long periods of time.

https://www.news.ucsb.edu/2015/015769/planetary-sweet-spot

 

Not all life may exist as we know and think of life. There are a few definitions of what determines life. Consumes Energy. Homeostatic IE maintains a steady state. Responds to its environment. Growth. Motion. Reproduction (a real biggie). Death. And then there is the philosophical determination of what intellect consists of. I think therefore I am or I am and therefore I think. Or the psychological arguments of Nature Vs Nurture in determining who we are. And then there are the broomstraw philosophers who will always wonder what it all about...

 

It is not the number of planets that is the problem. It is a planet that exists in an almost ideal conditions as does the earth.

Geologically stable is yet another important factor that earth possesses. The earth of a few billion years ago would have never allowed human level intelligent life to evolve even if life was given more time to evolve. Earth was simply too geologically unstable to allow life to evolve to any significant degree. Had the earth not stabilized none of us would exist and we certainly would nut be typing on these computers.

I have these conversations with some of my more creationist friends who cite divine design as the reason for our existence. I cite my personal 'jackpot' theory which fits either point of view. Maybe we're singularly blessed. Maybe we're winners in the galactic jackpot - our little speck of dust won against gigantic odds. Either way, I wish we'd be a little more careful with it.

 

https://www.theverge.com/2019/7/10/20687434/amazon-sellers-nomad-merchants-products-malls-walmart

Discontinued nail polish can be astonishingly lucrative, but not these colors. A dinosaur riding some sort of motorcycle? No way. But these Jurassic Park Jeeps look promising, and an Amazon app on his phone confirms that each could net a $6 profit after fees and shipping. He piles all 20 into his cart.

It’s not a bad haul for a half-hour’s work, but it’s not great either. He consoles himself that he hit upon a trove of deeply discounted Kohl’s bras the day before as he left East Brunswick, New Jersey, on his way here to Edison. Home is still 300 miles away, in Tyrone, Pennsylvania, and there are plenty of stores between here and there.

Anderson is an Amazon nomad, part of a small group of merchants who travel the backroads of America searching clearance aisles and dying chains for goods to sell on Amazon. Some live out of RVs and vans, moving from town to town, only stopping long enough to pick the stores clean and ship their wares to Amazon’s fulfillment centers.

 

Back before the USSR fell a Swede told me one of the problems back home in Sweden was Poles. They would come to Sweden to commit crimes in order to be jailed because life in jail in Sweden was better than life living in Poland. It's all a matter of perspective and what you make out of life.

 

Not all life may exist as we know and think of life. There are a few definitions of what determines life. Consumes Energy. Homeostatic IE maintains a steady state. Responds to its environment. Growth. Motion. Reproduction (a real biggie). Death. And then there is the philosophical determination of what intellect consists of. I think therefore I am or I am and therefore I think. Or the psychological arguments of Nature Vs Nurture in determining who we are. And then there are the broomstraw philosophers who will always wonder what it all about...

I am not referring to just life. Certainly life can exist in he harshest conditions imaginable. The type of life I am referring to is at a much higher order. Lifeforms that can create, build and communicate at a intelligent level. A life form intelligent enough to create technology that improves that life forms way of life. Lifeforms that are capable in living outside of their natural environment through use of technology.

And I still believe that in order for such a life form to evolve it needs a very special set of environmental circumstances that make this possible. And I still contend that part of our success on the evolution stage had a lot to do with the tools that we had other than our brains. I still contend that much of the evolution of the humanoid brain had a lot to do with he fact that we were able to learn through the manipulation of the world around us.

 

I am not referring to just life. Certainly life can exist in he harshest conditions imaginable. The type of life I am referring to is at a much higher order. Lifeforms that can create, build and communicate at a intelligent level. A life form intelligent enough to create technology that improves that life forms way of life. Lifeforms that are capable in living outside of their natural environment through use of technology.

And I still believe that in order for such a life form to evolve it needs a very special set of environmental circumstances that make this possible. And I still contend that part of our success on the evolution stage had a lot to do with the tools that we had other than our brains. I still contend that much of the evolution of the humanoid brain had a lot to do with he fact that we were able to learn through the manipulation of the world around us.

What is so special about our environmental circumstances? In just our galactic sweet zone zone there should be millions of possible Goldilocks planets orbiting stars. Each star has the possibility of one or two planets within zone that might be similar to earth on a some X percentage of those systems. Everything we have learned in the past 20 years has increased the chances of large numbers of earth twins, not decreased the chances.

http://science.time.com/2013/11/04/...ecial-there-could-be-20-billion-just-like-it/

 

What is so special about our environmental circumstances? In just our galactic sweet zone zone there should be millions of possible Goldilocks planets orbiting stars. Each star has the possibility of one or two planets within zone that might be similar to earth on a some X percentage of those systems. Everything we have learned in the past 20 years has increased the chances of large numbers of earth twins, not decreased the chances.

I have already mentioned it. I stable rotation which means somewhat stable weather. A stable orbit close enough to the sun but not too far away from the sun. Geologically stable.

These are not my theories. I wish I could find the article but basically it stated that advanced life outside of earth might be more rare then you might think. There were too many things that went just right here.

 

I have already mentioned it. I stable rotation which means somewhat stable weather. A stable orbit close enough to the sun but not too far away from the sun. Geologically stable.

These are not my theories. I wish I could find the article but basically it stated that advanced life outside of earth might be more rare then you might think. There were too many things that went just right here.

I see zero evident that those specified conditions are special in anyway. Those conditions should fall in the normal range of planetary variation per X number of star systems where even one in a thousand of the earth-like planets means huge numbers just in the Milky Way. Earth is much more likely to be mundane, dull and ordinary instead of special.

 

If probability had any efficacy, we would have verified it with our radios. We could tune in many worlds. Or past worlds.

There is the un-known, but there is no probability. Life is singular and only self propagating. Why?

If we understood every atom and every galaxy, would that explain life and the living?

It would make life an even bigger mystery.