Do you think that emergence of intelligent civilizations in the universe is common or rare?

It must be extraordinarily rare since there have been no artificial signs detectable from space. A Type 2 to Type 3 civilization would be readily identified due to emissions or artificial constructs - anything in space not made by nature would be a dead giveaway. And intelligent civilizations in this galaxy would have had around 4 billion years lead time from the present to establish itself (once the galaxy stabilized).

What many scientists overlook or choose to disregard is the idea that life does not intrinsically form where life is supportable. The Drake equation and the scientists of Carl Sagan's era postulated that there is a 10% chance of planets sustaining life to have it, and a 100% chance that life will become intelligent. That is excessively optimistic when you research the biology of evolution and the incredibly low chance of forming DNA from enzymes, moving to multi-cellular organisms, sexual reproduction, and then sentient intelligence. There is, afterall, ONLY one kind of life that ever formed on the planet: DNA-based, and out of the hundreds of million species ONLY one species that has been capable of culture. Those parameters in the Drake equation can be taken to mean 10^-18 chance or something ludicrously pessimistic to infer that we are the only intelligent life in the galaxy if not the universe. The most likely explanation why other civilizations are not there is not because they destroy themselves, but because they are most likely just not there.

Some scientists believe we are the first intelligent species to ever form.

Intelligent aliens wouldnt destroy themselves.If a civilizations is getting closer to a type 1 society,it has moral principles and they wont destroy themselves.When they reach a type 1 and when they get close to a type 2 civilization,they are immortal.They have a tehnology against everything.Type 3 civilization is a true immortal civilization,which means that they could even escape a dying Universe and they could get in another one,or they could even create their own Universe.Creating Universes is more for a type 4 civilization.

Now,lets talk about how many other civilizations there could be.First,we dont know anything about how common are civilizations,so everything would be just guessing.The only way that we could know how many civilizations there could be,is to search for atleast a few millions of Earth-like planets,and from that data,we could have an estimation.

Logic is something that could give us a good view on other civilizations.For example,we are here on Earth,and our civilization have a potential to become God-like.We know that evolution exists,and life exists.So,on every habitable planet life should happen.With evolution,life tends to become more adapted,more complex,and more advanced,if beings are in a pressure for survival.

So,logic and evidences tell us that life is extremely common in the Universe.When we talk about civilizations,they should be rare,because it takes a lot of time and luck for a being to rise above animal kingdom.But because there are billions of habitable planets just in our galaxy,even if civilizations are rare,a minimum number of civilizations per galaxy on average should be atleast a few hundred.Realistic number is in thousands.So some range would be between 300 and 300 000 civilizations per galaxy.It could be just 500,lets say,or it could be even 200 000.Remember that not all civilizations are interstellar.Even if there are 200 000 civilizations in our galaxy,just a tiny fraction would be interstellar.Most of civilizations wouldnt have a tehnology.

There is also a one very important thing.Advanced civilizations could create other civilizations by altering the DNA of animals which live on that planet.So,those aliens could create as much civilizations as they want.They could even populate every single planet in our galaxy with a civilization.So,its even harder to know how many civilizations are there.

We should know how many civilizations are naturally possible in the Universe,without intervention of an advanced aliens.That will give us a realistic view on how common are civilizations.

So,for the end.Life is a standard thing in the Universe.Evolution happens.Civilizations happen.So,civilizations should be rare,but they should also be a standard thing in the Universe.A number for that standard is anywhere between a few hundred,to a few hundreds of thousands of civilizations on average per galaxy.

There could possibly be millions upon millions of intelligent civilisations in the universe.

/ / "do you suppose that most intelligent civilizations destroy themselves or render themselves irreversibly stagnated, hence the lack of any tangible evidence that we see?" / /

Imagine this hypothetical :

Every supernova ever, is a civilisation reaching the point of particle collisions. (eg LHC Large Hadron Collider)

Each increasing the energy of their collisions to an unknown critical energy, whereupon they cause a chain reaction which converts their home planet to energy. (via E=mc^2)

I read somewhere to instantly convert an adult human to energy via E=mc^2 would be equivalent to 17,000 Hiroshima size H_bombs.

Imagine then, an entire Planet.

PS : I bet one of our mathematical friends could tell you the total energy of the Earth (E=mc2^) and how closely it matches the energy of your average supernova.

All the best.

Rare. Exceedingly rare. So rare in fact that the nearest (assuming that another even exists at the present time) is in a galaxy in the far distant universe: much too far away to even detect.

That of course gives an elegant solution to the problem of why we have never detected life in space: it simply does not exist, or at least not within detection range.

Cheers!

Check out the Drake equation. There are many variables, many of which we can only have a "best guess" estimate for.

Yes. We're still waiting to observe the first one.