Are we alone in the universe?

Why do you assume that your potential interlocutors believe this?

You miss at least a couple of signal points here. If you are sitting in your house, and i am sitting in my house, and we are miles apart, then it is reasonable to say that you and i are alone. Now, if we had a telephone or a radio, we could speak, and to that extent, we would no longer be alone. However, it the time it took for one of us to speak and that message to be received at the other end exceeded our life expectancy, then we would be, functionally, alone once more. If someone lives on a star sixty light years from our planet and i send out a message, even it received and replied to, the likelihood is that i won't be alive when the reply comes in. Were humns ever established on Mars, if you got on the radio and said "Hello," you'd have to wait 40 minutes to get a response. Conversation would be difficult at best. Over intra-galactic distances it would be impossible. You could send a message out into the void, but it would be silly to expect to converse. So, yes, we are alone.

A better question would be, are we unique. That might be worth discussion, in the sense of are we the only sentient, self-aware, technological civilization.

"A better question would be, are we unique. That might be worth discussion, in the sense of are we the only sentient, self-aware, technological civilization."

Good point. I tried to edit my comment to change the title but it wouldn't let me. I spent more time researching the thread than I did coming up with a good title (which is equally important to get conversation rolling.)
However, I do disagree with our definitions of "alone." Some people think you are a quack to believe that extraterrestrial life may exist. I was presenting an argument for why I think it most likely does exist. When I asked are we alone in the universe, I meant are we the only living beings in the universe. Are we special in that way.

Yes, if I could change the title I would write "are human beings unique?"

Of course, i cannot give an unassailable answer to that question. I doubt that we are on the only planet having life. (I won't go into or do any question-begging about what one means by life.) But if most of the life in the cosmos, or all of it other than the examples we have here, are single-cell organisms, i can't think it's a very important question to answer. I suspect that life is ubiquitous, for pretty much the same reasons you gave in your opening post. (I don't necessarily subscribe to your point of view exactly, but close enough.)

So where would you go from there, were it established that life is abundant?

I think that, once weve determined that life exists in ONE MORE place, like Mars for instance, that would set off a huge research effort to then look for the useable practical commonalities that we may discover. For example.
1Is apoptosis a universal thing or are there lifeforms that are basically immortal (Margulis theorized that somewhere in the deep Paleoproterozoic, life on our planet did not yet employ a form of cellular apoptosis

2Is life necessarily evolving through bilateral symmetry like on earth. (The number of non bilaterally symmetric species are few in species but large in number)

3Is life Galactically Carbon Based? Everybody has read "The Day of the Triffids" as a kid

4What forms of metabolism can life embrace throughout the galaxy (Im stickin close to home first)

I think "sticking close to home" is the only reasonable thing to consider, given intergalactic distances. I've read some speculation that silicon-based life might be plausible, but that's based on the rather simplistic observation that both carbon and silicon have a valence of four. The oxide of carbon is a gas, the oxide of silicon is silica--the two elements react very differently. I think another interesting question would be whether or not we would recognize life forms if they don't conform to our notions of what life must be like.

Theres a bunch of multi-valent amphoteric elements that could really be the base of life( like Phosphorus Selenium and even iron).We could have "men of steel" out there.

Silica is a stretch because many of the necessary intermediates don't
exist In Si. But it makes great scifi. Of course, there are entire genera of carbon/silica based PLANTS

ke bamboo Theres a bunch of multi-valent amphoteric elements that could really be the base of life( like Phosphorus Selenium and even iron).We could have "men of steel" out there.

Silica is a stretch because many of the necessary intermediates don't
exist In Si. But it makes great scifi. Of course, there are entire genera of carbon/silica based PLANTS

To give a quick response, I think in a sense we are unique in some ways. The way we evolved over the past billion years influences the way we are today. I think the way we think, to some degree our consciences, the ways our bodies work, the fact that we are social mammals, all has to do with unique evolutionary path we took. Had certain environmental conditions differed, we may have evolved completely different characteristics.
After all we share a common ancestor with apes, and all of the different species of apes alive today have different personalities, and characteristics. What if one of them would have involved intelligence on par with us. What would their society look like. Would they be at constant war like us? I doubt the bonobos would be.
"Most studies indicate that females have a higher social status in bonobo society. Aggressive encounters between males and females are rare, and males are tolerant of infants and juveniles. A male derives his status from the status of his mother.[35] The mother–son bond often stays strong and continues throughout life. While social hierarchies do exist, rank plays a less prominent role than in other primate societies"
Anyway I could probably start a whole new thread on that.

So, if there is intelligent extraterrestrial life, are they DNA based? I imagine it would be something similar to DNA.

Seems like there should be lots of life out there doesn't it.

Unfortunately earth life is the only data point on the chart right now. And you can't get a slope from a point.

we can see the existence of G and T in the spectra of stars.

There are other crystalline substances that can bond into long chains , and even boulangerite like "helices". the "geometry of life " would be another interesting little sidetrack Id wanna look into were I still in grad school .Kids today have super wide horizons of really big questions to play with.

don't be a goddam party pooper ros.
Hell, gunga has found entire alien shopping centers on Mars

I think it is a safe assumption that any life form would have to be based on self-replicating chemicals. FM has asked if apoptosis is universal. If it is not, then life forms may not need to reproduce (which asks the question of how they arise).

Once you reach the level of civilization, then other factors come in which have nothing to do with our specific evolutionary history. Life forms which are sentient, self-aware and which manipulate their environments would need to have a certain high degree of cooperative behavior. They would also need to have individual personalities--or so it seems to me. A hive mentality is not one which would foster innovation. That individuality would also suggest that consensus is needed to achieve anything.

I understand that they were wiped out in the customer stampede on Black Friday.

OHHH NOOOOOOO. I wonder if they had a Martian equivalent of Star Wars crap?

An intergalactic Walmart; What could be worse? I can just picture the aliens violently charging forward on black Friday at an Andromeda galaxy Walmart, desperately trying to snatch the last pair of Nike shoes for their child's four alien feet.

Good point. Maybe the bonobo's are too cooperative, and not competitive enough for our type of intelligence to evolve.

AHEM, aliens may have several pairs of podal locomoters , or maybe one set of three.
That certainly would screw up the assembly lines.

BTW, weve been entertaining ourselves on evolution threads for almost 10 years and we have our favorite "foils". Seems you have an interest in the subject. That's gratifying because the Fundamentalist worldview can sometimes be tiring. SO If we haven't given youse a welcome, well, Welcome.

Most of us are harmless and some, its been said, even have a sense of humor. I have seen no evidence of any such affliction however.

My guess would be that if 4 out of 6 most common elements in the universe are the 4 most common elements in our bodies (C, H, N, O), than most life in the universe may contain those 4 elements and hence be carbon based. The seventh and ninth most common elements in the universe are silicon and iron, so there may be some planets with conditions (distance from sun etc) conducive to life where silicon and iron are more abundant. In those situations, those elements may form the basis of life on those planets, if life is as resilient elsewhere as it is on earth (like extremophiles).