How likely are we to find extraterrestrial life?

[otseng]

Many NASA scientists think we're on the verge of finding alien life.

Ellen Stofan, NASA's former chief scientist, said in 2015 that she believes we'll get "strong indications of life beyond Earth in the next decade and definitive evidence in the next 10 to 20 years."

Many astrophysicists and astronomers are convinced that it's not a matter of if we'll find life — it's when.

https://www.businessinsider.com/nasa-pl ... de-2019-11

Questions for debate:
- How likely are we to find extraterrestrial life?
- What empirical evidence is there that any extraterrestrial life exists?
- What are the implications if extraterrestrial life exists or do not exist?

[DrNoGods]

[Replying to post 10 by Menotu]

I believe that there is likely already life here that is ET like, if not currently absolutely in the past.

What do you mean by "ET like"? Are you using "ET" simply as short for extraterrestrial (in which case the phrase "ET like" is hard to decipher), or are you referring to something like the E.T. character in the 1982 Spielberg movie?

Will we ever find it?
I believe, almost 100%, that some have. Will modern science admit to it?

Are you suggesting that modern science has "found" some kind of alien life on Earth but is hiding the information for some reason? This sounds like a conspiracy theory, but it depends on your definition for "ET like."

There is a huge difference between intelligent life of the kind being sought by systems like SETI, and what is expected to be a far more likely situation where much simpler life forms more like bacteria are found on a planet or moon outside of Earth. If such a discovery is made (life of any kind on another celestial body) it will be very interesting to see how the various religions will respond to it. Would their response be very different if the first discovery was a bacteria-like creature, rather than something far more advanced and having what we would call intelligence?

The people responsible for creating the most popular monotheist religious documents (eg. the Bible, the Quran, etc.) had no idea that microorganisms existed, so they made no comments about them or their "creation." Are there any implications for religious dogma if bacteria-like creatures are found on another planet or moon? Or, because microorganisms are not mentioned in the holy books, does that exempt them from any influence on interpretation of "creation" events when it comes to creatures large enough to see with the naked eye?

If science had found some sort of alien life what would be the reason for keeping that quiet? I don't see any benefit to hiding such information if it did exist.

[Menotu]

[Replying to post 11 by DrNoGods]

Are you using "ET" simply as short for extraterrestrial

Yes - sometimes my spell check doesn't work and I was too lazy to copy/paste the right spelling at the time to be honest

Are you suggesting that modern science has "found" some kind of alien life on Earth but is hiding the information for some reason?

That's a loaded question. While I can't say for sure, having several friends in the military (from new recruits to high ranking officers to officials with secret security clearance in a few different areas of the country) I would lean towards 'yes, but...' (with the but being depending on how one defines alien life).

There is a huge difference between intelligent life of the kind being sought by systems like SETI, and what is expected to be a far more likely situation where much simpler life forms more like bacteria are found on a planet or moon outside of Earth.

Of that, there is little debate.

If such a discovery is made (life of any kind on another celestial body) it will be very interesting to see how the various religions will respond to it.

And frightening I suspect.

If science had found some sort of alien life what would be the reason for keeping that quiet?

I think there can always be a reason. Rather it's a valid, legit reason or not is the question.

I don't see any benefit to hiding such information if it did exist.

I think that depends on whom you're asking.
If one looks in to the subject enough, you find a myriad of claims of evidence that was thwarted by 'powers that be' (aka the government I suppose). And while I don't believe every single issue like that I come across, it does make you wonder some.
Perhaps there's more at work than simple inept government nannies at play?
Any rate, it's fun to consider.

[Willum]

Well, the likelihood of discovering extraterrestrial life inside the solar system is pretty high. It might not be very interesting life, however. Microbes, things that can eke out a living on the meager amount of energy elsewhere.
The other question is if that life has been able to rise above the waves, be it water, ammonia or methane. If you can’t do dry land, you can’t do electronics or rocketry.

The implications?
One is why would God/gods make really boring life on other worlds? Certainly not to worship them.
Other implications are the universe is as science expects it.

[Still small]

If you (or anyone else reading this thread) are religious ... would your views change if life were found elsewhere in the universe? How would that impact the idea that humans are special creatures? Would it negate that? Or would it be just be another subject to try and analyze and explain within the framework of whatever religion one follows? That is probably a question for another section of the website, but I've always assumed that the great interest in the question of whether there is life elsewhere in the universe is driven in large part by this particular issue ... ie. are humans special in the grand scheme of things, or just creatures who evolved a highly complex and capable brain that allows them to ponder these kinds of questions.

Would my (religious) views change if life were found elsewhere in the universe? Not necessarily, as my view of life is based upon that which God has revealed through the Bible. The Bible speaks of God’s creation and involvement with life on and only on this planet, Earth. It makes no reference to the possible existence or nonexistence of life anywhere else within the natural (physical) universe. Whilst it would greatly intrigue my interest, it would not overly worry me as I’m often amazed at God’s accomplishments according to His purpose, realising that (virtually) nothing is beyond His capabilities. Nor should I attempt to restrict or limit His works to that according to man’s abilities.

On the other hand, though pointed out earlier (by Divine Insight, post 6) the fact of total nonexistence of life elsewhere can never be proven (you can’t prove a negative), if it were possible to prove the total nonexistence of life elsewhere despite the possibility of numerous suitable habitats, would that change your views and beliefs about life here on Earth? Would you accept that maybe it is special and according to a purpose?

Have a good day!
Still small

[Willum]

I'd also forgotten one BIG detail.

How long is intelligent life likely to be in the history of its planet?
Humanity has arguably been here 140,000 years, if I remember correctly.

We have mastered the radio for only 100 years or so.
We are also responsible for mass extinctions that could easily come back and murder us.

That means out of the Billions of years of life, only 100 (call it 200) years have we been smart enough to look for it, and we may be extinct in a biological eye-blink.

200/1000000000 is a very small amount of time to be able to find other life.

If we make a order of magnitude assumption that other life will do the same thing, that means the crude odds of us every finding intelligent life are 200/1000000000 x 200/1000000000

or 4 in 10^13.

Increase that for every nearby star, decrease it for the distance of those stars... it remains a very small number.

[DrNoGods]

[Replying to post 14 by Still small]

The Bible speaks of God’s creation and involvement with life on and only on this planet, Earth. It makes no reference to the possible existence or nonexistence of life anywhere else within the natural (physical) universe.

But that is because the people who wrote the text compiled into the Christian bible had no idea what the lights in the sky were, that other planets might exist, what a planet even was, that microorganisms existed, etc. So it is not surprising that the bible makes no reference to life elsewhere in the solar system, or in our galaxy, or the universe, because at that time no one had any idea what these things were. The lights in the sky were thought to be resident to a series of domes located at different distances from Earth, rotating about Earth as Aristotle had proposed. This was the accepted view until Copernicus proposed, in 1515, that the Earth was just another planet like Venus and that planets orbited the sun, and he didn't publish his famous treatise until 1543, just before his death (many centuries after the biblical texts). The biblical authors could not possibly have concocted a creation story including life on other planets due to the scientific ignorance of humans at that time.

... if it were possible to prove the total nonexistence of life elsewhere despite the possibility of numerous suitable habitats, would that change your views and beliefs about life here on Earth? Would you accept that maybe it is special and according to a purpose?

IF such a thing could be proven, then it would certainly point to life existing only on Earth as a unique, extremely rare occurence. But it would not prove it was due to the action of a god. It would just mean a very unusual thing happened. If we're talking hypotheticals, if humans had never evolved but the other 99.99...% of all life that has existed on Earth otherwise existed as it did/does, what would that say about the creation story that you believe? Go back in time just 10 million years ... only 0.2% of the age of the Earth ... and there was nothing resembling a human on this planet, but it was teeming with life. Why did god wait some 4.5 billion years before "creating" humans after the planet formed, and create the illusion that life progressed from much simpler (but still very complex) single-celled organisms to mammals and primates over a very long period of time? You have to be a YEC to believe the biblical creation story, because it makes even less sense if twisted (as has been done by some) to try and make the story consistent with the known age of the Earth.

Also, if Earth is the only planet in the entire universe with life of any kind, you'd have to ask a whole slew of questions about why a god would only choose one planet out of billions or trillions for his experiment. Why not bless countless other habitable planets with intelligent life forms instead of having them all be essentially useless celestial bodies? Why even create the rest of the universe at all when only one tiny solar system is important? It seems that a god like that is not only jealous as the bible states, but also very selfish. The creation myth of Christianity, and the many other creation myths humans have invented, is just untenable in the light of modern science.

[otseng]

Came across this interview of Helen Sharman (the first British astronaut and first woman to visit the Mir space station):

Aliens exist, there's no two ways about it. There are so many billions of stars out there in the universe that there must be all sorts of different forms of life.

https://www.theguardian.com/lifeandstyl ... uch-i-know

Sharman has no uncertainty that aliens exist. However, there must be does not mean any actually exist. So, here is another case where a scientist has complete belief in something where there is no actual empirical evidence for its existence.

Again, if a scientist can believe in the existence of something without any empirical evidence for it, it is not ridiculous for a Christian to believe in God even if there is no supposed empirical evidence.

[DrNoGods]

[Replying to post 17 by otseng]

Sharman has no uncertainty that aliens exist. However, there must be does not mean any actually exist. So, here is another case where a scientist has complete belief in something where there is no actual empirical evidence for its existence.

This person is an astronaut as she has been to space, and has her degrees in chemistry, but just because she may believe in alien life personally, that carries zero weight as far as whether it actually exists or not. Just her personal opinion and nothing more. Analogous to Newton's certainty that a god existed, for example.

Again, if a scientist can believe in the existence of something without any empirical evidence for it, it is not ridiculous for a Christian to believe in God even if there is no supposed empirical evidence.

I would agree ... the operative word being believe. Anyone can believe anything, whether or not there is empirical evidence for it. The existence of extraterrestrial life has some probability that is nonzero because of two observables ... the existence of at least one planet that has life, and the existence of many thousands of exoplanets, some in the habitable zone (for life as we do know it). So although there is no empirical evidence for extraterrestrial life yet, there are reasons to expect that it is there. Dr. Sharman's comment in the linked article was this:

"There are so many billions of stars out there in the universe that there must be all sorts of different forms of life. Will they be like you and me, made up of carbon and nitrogen? Maybe not. It’s possible they’re here right now and we simply can’t see them."

So she is using the same probability argument mentioned earlier in this thread, but carried it further and said "Aliens exist, there’s no two ways about it." I'd translate that has indicating that she believes the probability is so close to 1 that she considers it equal to 1. But that is a step too far I think.

It is not ridiculous for Christians to believe in a god, but I'd argue that this is not the same analogy as a scientist believing in the existence of extraterrestial life. The latter at least has some information for its inference (one planet with life, many exoplanets exist), while the former is belief based on faith alone (often derived from acceptance of the content in a particular "holy" book). If just one of the many thousands of gods that humans have invented over the millennia had made itself known definitively, then it would greatly increase the odds that the Christian god could exist because we'd know from one instance that gods can, in fact exist. But this has yet to happen.

[ttruscott]

The Fermi paradox: if Earth, a fairly young planet has life and life is so easy then the vast numbers of older planets should have produced ancient civilizations by now...where are they? Hiding behind a Vulcan decree to not show themselves until we get interstellar capability?

[DrNoGods]

[Replying to post 19 by ttruscott]

The Fermi paradox: if Earth, a fairly young planet has life and life is so easy then the vast numbers of older planets should have produced ancient civilizations by now...where are they? Hiding behind a Vulcan decree to not show themselves until we get interstellar capability?

There was a long discussion on this in another thread here (don't have the link handy), but there are many reasons why any other civilizations that might be out there can't create communications that we could see, and vice-versa. Our own "radio bubble" is only about 130 light years (distance our first radio signals have travelled), so any electromagnetic communication that we have been able to generate could only be seen by a civilization within that extremely tiny distance from Earth (it is 26,000 light years just to center of our own galaxy).

Another issue is divergence. Even with collimated laser beams, or directional radio signals, at the highest powers we've been able to produce, the fundamental problem of beam divergence would kill the ability of electromagnetic signal from getting across the universe with any detectable signal level. Beam divergence is inversely proportional to the diameter of the beam. If we sent our most powerful, collimated laser beam, as large in diameter as we could make it, it would be many billions of miles in diameter at just 4.2 light years from Earth (the closest star to Earth). So only a teeny, tiny fraction of the beam could be relayed to another receiver located elsewhere, even if the first star had a receiver as large as the star. A check of the signal level of the Voyager signals, which are just a tiny fraction of a light year, illustrates the problem with trying to communicate across vast distances using radio signals.

https://voyager.jpl.nasa.gov/mission/status/

Voyager 1 is only 0.00243 light years from Earth and we receive only about 1e-21 of the signal from the 20W transmitter (we receive about an attowatt of signal 1e-18W). The rest is lost to divergence.

So the idea that electromagnetic signals from intelligent civilizations should be blasting Earth if they were out there is just not how it works. Even if such a civilization existed within our own galaxy (and it is far more likely any life that does exist is microbial), and they started transmitting signals exactly in our direction thousands or millions of years ago (and the pointing accuracy of that is unlikely given the tiny size of Earth), it is highly unlikely we'd see them due to the reduction in signal levels due to divergence, and to the very brief period of time humans on Earth have even had the capability to detect the signals (they'd have to have been emitted by the alien civilization within just the right time window to catch our ability to see them ... anything passing by prior to that we'd have missed).

I'll try to find the link to the prior discussion on this, which was pretty long and involved and had a lot of numerical examples of why the Fermi paradox just doesn't make any sense.