no ETs in universe

[Trakar]

Does nature ever produce things so rare that they don't have another of their kind? Is there an example of any particular ever discovered that belongs to a class of things, where the particular is the only member of that class? There is no evidence that I know of, apart from the existence of the Earth, that our solar system and the processes that lead to its formation is particularly special compared to other solar systems. So if the general conditions that lead to the formation of the Earth are not rare then I don't think intelligent life is extremely rare in the universe. But this is just my intuition based on the fact that nature tends to have a certain regularity, wherever we may look.

Out of the thousand or so ET planets that we know of the one that most closely approaches the Earth in Primary HZ orbit, mass and composition, is the planet Venus (planets much more extreme than Venus are being found in other stellar systems and are being touted as "Earth-like" and "habitable" ..., really!?). Show me another Earth and I think youd have a fair shot at finding life. Venus ain't Earth-like, and neither are any of the extrasolar planets I've looked at the data for so far.

[Trakar]

The main target of the cartoon appears to be the fact that
we are only looking for certain types of signals. I think that
criticism is a bit unfair because we are not limited so much
by what what we think we should be looking for as by what
we have the ability to detect.

The main target of the paper (which I haven't read -- I only
read the article) appears to be the fact that we only have a
single example of biogenesis from which to extrapolate the
"laws" of biogenesis. That makes uncertainty very great and
makes speculation more useful than observation -- until we
actually find some other examples to observe.

-- Jeff, in Minneapolis

^^^^^Very much this!

[Daffy]

As far as we can tell...the big bang. Is there a copy of Earth some where? Well if the universe is infinite in size then yes but it doesn't matter because it effectively doesn't exist to us anyway.

A planet with life? I bet they are all over the place. Most probably carbon based. Will it be DNA/RNA type molecule based life? Who knows but I wouldn't doubt it.

Currently our sample set is 1. I'd love for "life" to be discovered on Europa that is not based on DNA/RNA because it would show that different forms of life are possible. But I'd settle for DNA like based life too :P

But even the Big bang may have happened more than once according some variations on the multiverse theory. All I am saying (OK, asking, really) is that the only evidence we have is that intelligence can exist---so it seems to me the odds are tipped slightly in favor of other intelligences existing somewhere. Otherwise we have to explain why it only happened here. Don't we?

[Gomar]

so it seems to me the odds are tipped slightly in favor of other intelligences existing somewhere. Otherwise we have to explain why it only happened here. Don't we?

There is nothing to explain.
Odds are not tipped in anyone's or in any galaxy's or planet's favor. Odds are uniform no matter where you look. Given enough time, someone somewhere has to win.
It's the same reason that J.Lo's mom won $2m at a slot machine in A.C.; or why a man won $85k playing Take5 with 15,16,17,18,28; or why I did not win the $380 million Mega Millions jackpot, but someone else did.

Did the people who just died at that plane crash in Reno have better odds of being killed when they were born than you or I? No. It's all random chance.

Fact is everyone who playes the lottery has an equal chance/odds of winning; odds are not "stacked" to favor Ph.D's, plumbers, women, the deaf, blondes, red-necks, clowns,
or members of this forum.

There is life on planet Earth because that's how the dice rolled.

[Perikles]

If you were to shuffle cards 10million times, a royal flush must come up a few times..

You should never really use the word must when talking of probabilities. There is no certainty that a royal straight flush will turn up in 10 million deals. The probability of a RSF is 1 in 649740, so the probability of NOT a rsf is 649739/649740. So the probability of not dealing a RSF in 10 million deals is that number to the power 10 million. I have no idea what that number is, but one thing is certain, it is not zero. So the probability of one RSF in 10 million deals is very near one, but not exactly equal to it.

The point of this nerdy aside is that even with (say) 10^30 habitable planets out there, the existence of ET is never certain, just probable. Though it's worth a bet.

[Daffy]

There is nothing to explain.
Odds are not tipped in anyone's or in any galaxy's or planet's favor. Odds are uniform no matter where you look. Given enough time, someone somewhere has to win.
It's the same reason that J.Lo's mom won $2m at a slot machine in A.C.; or why a man won $85k playing Take5 with 15,16,17,18,28; or why I did not win the $380 million Mega Millions jackpot, but someone else did.

Did the people who just died at that plane crash in Reno have better odds of being killed when they were born than you or I? No. It's all random chance.

Fact is everyone who playes the lottery has an equal chance/odds of winning; odds are not "stacked" to favor Ph.D's, plumbers, women, the deaf, blondes, red-necks, clowns,
or members of this forum.

There is life on planet Earth because that's how the dice rolled.

But when one person won the lottery, the evidence indicated a better than zero chance that someone else would in the future. And they did.

[ravens_cry]

Even if life develops again, and even if some it is life that uses tools and communicates in complex ways that we call "intelligent life", there is no certainty they would invent radio, much less interstellar travel, something we have barely begun to do at the most stretched definition.
The energy requirements are beyond immense.
Look at us, we have used nuclear fusion. That's about the second or third most efficient process we know about for turning matter into energy (is a black hole accretion disc more or less efficient?), and the energy requirements still look huge.
I hope there is other minds out there, I do, but, in the end, we really don't know.
Not yet.

[iquestor]

Out of the thousand or so ET planets that we know of the one that most closely approaches the Earth in Primary HZ orbit, mass and composition, is the planet Venus (planets much more extreme than Venus are being found in other stellar systems and are being touted as "Earth-like" and "habitable" ..., really!?). Show me another Earth and I think youd have a fair shot at finding life. Venus ain't Earth-like, and neither are any of the extrasolar planets I've looked at the data for so far.

A Thousand or so?? We are at 684, with more being announced weekly. Kepler has a candidate list of 1200 which require another transit or two. What the data begins to show is that rocky planets are fairly common, possibly as high as 40%. We only have a few that are within the margins that are habitable by the data we have so far, and the error factors for these are still significant, so right now, we can't really say if they are more comperable to Venus than to Earth. However in 10 - 15 years (when we have a real candidate list to work from) we should be able to bring to bear more tools on these worlds and tune in a little further -- like spectroscopy.. I think by then we will have a dozen or so worlds that show strong indications of being reasonably earthlike by the presence of CHON, and ranges for temperature, gravity, and other factors, planets that are possibly inhabitable, of not inhabited.

[iquestor]

Daffy -- Actually, the laws of probability are what indicates the chance. The fact that someone won has zero impact on the probability of an event happening. evidence has nothing to do with it.

A coin toss is 50/50 for heads over tails. If a person flips a balanced coin10 times and it always comes up heads, the evidence seems to suggest that heads is the more likely event, however the probability is still 50% and always will be.

[Daffy]

Daffy -- Actually, the laws of probability are what indicates the chance. The fact that someone won has zero impact on the probability of an event happening. evidence has nothing to do with it.

A coin toss is 50/50 for heads over tails. If a person flips a balanced coin10 times and it always comes up heads, the evidence seems to suggest that heads is the more likely event, however the probability is still 50% and always will be.

I get that, but---question: we are not talking about a 50/50 coin flip; we are talking about billions and billions of galaxies each with billions and billions of stars (Hi, Carl!). All I am asking is, since intelligence arose on Earth (at least), surely the odds for intelligence elsewhere are not zero---are they? I doubt that they can be calculated accurately with only one planet for evidence, but surely the odds are not zero. Or am I missing something? For there to be zero chance of intelligence elsewhere, it would then require some mechanism unique to Earth for it to have risen here at all. Wouldn't it?

[Jeff Root]

iquestor,

I think you missed the point about the lottery.

If millions of people buy lottery tickets and nobody wins this
time, and the prize increases, people millions of people will
buy tickets next time, too. But if the lottery is held over and
over and nobody ever wins, people will stop buying tickets,
because the evidence is that you can't win. If somebody wins,
the evidence will be that you can win, and lots of people will
buy tickets.

I used to hope that someday I 'd win a lottery. But eventually
I caught on from what I picked up here and there that the
chances of winning are pretty poor if you don't buy a ticket.

-- Jeff, in Minneapolis

[Jeff Root]

An a priori calculation of the probability of an event occurring
can only be done if one knows the rules for the calculation. For
events in nature, the rules can only be learned via observation.

-- Jeff, in Minneapolis

[kevin1981]

I think common sense is needed, when talking about the possibility of other life, out there in the universe. We hav'nt detected any, so we don't no if there is any. Like people have said in this thread, just because it has happened here, on planet earth, dos'nt necessarily mean it has happened anywhere else. I like to think that if life has happened here, then why not somewhere else, but, there is no evidence for it, so for me the answer is, we just don't know.

As for "intelligent" life, maybe we are the first...

[WayneFrancis]

But even the Big bang may have happened more than once according some variations on the multiverse theory. All I am saying (OK, asking, really) is that the only evidence we have is that intelligence can exist---so it seems to me the odds are tipped slightly in favor of other intelligences existing somewhere. Otherwise we have to explain why it only happened here. Don't we?

Your question was "Hmmm---can anyone think of anything else in the universe that has definitely happened only once?" I guess the better answer would have been :
The start of our universe only happened once.
once you start talking about stuff in the "multiverse" you might as well not ask the question.
I'd also say that given the current data it looks like our universe isn't in some cyclic model so currently I'm comfortable with saying that the big bang only happened once.

I completely agree with you on there being other intelligences out there. But then we could get into a debate about what is "intelligent". We aren't even the only creatures here on Earth with culture, tool use, advance problem solving, theory of self and arguably even language. I believe just like life is an emergent property of chemistry, I believe "intelligence" is an emergent property of life. Just the sheer numbers involved would suggest that there would be other planets out there that are almost just like Earth and I'd can't even fathom that there could have been some unique event that happened here on Earth that started life.

Like you are trying to point out, there isn't anything in the universe that seems "unique" in the general sense. I guess besides being sarcastic my answer of the "big bang" shows to what extreme you'd probably have to go to to find something.

[WayneFrancis]

Even if life develops again, and even if some it is life that uses tools and communicates in complex ways that we call "intelligent life", there is no certainty they would invent radio, much less interstellar travel, something we have barely begun to do at the most stretched definition.
The energy requirements are beyond immense.
Look at us, we have used nuclear fusion. That's about the second or third most efficient process we know about for turning matter into energy (is a black hole accretion disc more or less efficient?), and the energy requirements still look huge.
I hope there is other minds out there, I do, but, in the end, we really don't know.
Not yet.

Depends on your definition of efficient. Accretion disc have fusion going on in them.

[Colin Robinson]

I get that, but---question: we are not talking about a 50/50 coin flip; we are talking about billions and billions of galaxies each with billions and billions of stars (Hi, Carl!). All I am asking is, since intelligence arose on Earth (at least), surely the odds for intelligence elsewhere are not zero---are they? I doubt that they can be calculated accurately with only one planet for evidence, but surely the odds are not zero. Or am I missing something? For there to be zero chance of intelligence elsewhere, it would then require some mechanism unique to Earth for it to have risen here at all. Wouldn't it?

Logically, yes, the odds of intelligence emerging on a planet have to be above zero. On the other hand, it is logically conceivable that they are so low that you could search billions of galaxies (assuming you had the time and the technology to do so) without finding another planet with intelligent life. Indeed, it logically conceivable that our Earth is the only planet among billions of galaxies with life at all.

Whether that ought to be the preferred hypothesis, is another question.

Advances in astronomy have often shown our neck of the woods to be less unique than it seemed. For instance, it is possible to imagine a universe where only one world has mountains on it. Indeed there was absolutely no empirical evidence of mountains anywhere else, until the early 17th century, when Galileo made some observations which led him to conclude that there were mountains on the Moon... It is possible to imagine a universe where there are billions of stars, but only one star has planets. And we might, for all we knew, have been living in just such a universe, until the first exo-planets were confirmed in the 1990s.

[iquestor]

I get that, but---question: we are not talking about a 50/50 coin flip; we are talking about billions and billions of galaxies each with billions and billions of stars (Hi, Carl!). All I am asking is, since intelligence arose on Earth (at least), surely the odds for intelligence elsewhere are not zero---are they? I doubt that they can be calculated accurately with only one planet for evidence, but surely the odds are not zero. Or am I missing something? For there to be zero chance of intelligence elsewhere, it would then require some mechanism unique to Earth for it to have risen here at all. Wouldn't it?

To me, because of the sheer number of worlds out there, and taking the viewpoint that earth isnt anything special, I'd say the probability of life elsewhere, even another intelligence is close to 100%. But, we have no evidence, yet.

Jeff -- yes I did miss the point -- I was taking the post as it was without reading the previous posts. sorry.

[Paul Wally]

from what we can see in our neck of the woods, nature tends to produce highly complex and highly chaotic systems. whether or not you fart today can have huge consequences a million years down the line.

even if it were possible to recreate the conditions of the very early earth and the solar system to the maximum degree quantum laws allow us to, it stands to reason that life would evolve very differently (if at all) on that second earth. in that sense, i'd say nature produces uniqueness all the time. on the other hand, it seems that the basic laws and building blocks with which nature operates are universal. in that sense i believe the assumption that we are not alone is an almost 100% certainty. i wouldn't be surprised if even our galaxy was full of intelligent life.

There is however a difference between chaos and complex adaptive systems. Chaos is sensitivity to initial conditions leading to random phenomena without any perceivable pattern.
Life, on the other hand, can be classified as complex adaptive systems, which definitely has perceivable patterns and regularities and unlike chaos it's stable within some margin of external disturbances. So when we say that the emergence of life is sensitive to initial conditions, we have to clarify exactly what the variables are on which the intitial conditions are specified and how the emergence of life is sensitive to variations in these conditions. What I do know, at least in the case of the Earth, is that once life gets a foothold, it is everything but sensitive to disturbances like meteorites, comets, climate change etc. So the phenomenon of life on the whole, is existentially stable, the reason being that life is in essence adaptive, and with the emergence of intelligence it is even more adaptive.

Jeff Root:
An a priori calculation of the probability of an event occurring
can only be done if one knows the rules for the calculation. For
events in nature, the rules can only be learned via observation.

We do have some rules to go on, ,like the laws of physics and chemistry. So it's not a complete guessing game and there's no need to scout the entire galaxy for evidence.
Also, I don't think we should look at the emergence of life and intelligence as a contingent event , but rather as a class of phenomena. If we look at it in this way then it's possible to study the phenomenon with computer simulations, using only the laws of physics, chemistry and whatever evidence we currently have at our disposal. In such a model we could then vary the initial conditions to see how sensitive the emergence of life is to initial conditions. In this way we can at least get a qualitative idea of the dynamic processes. I have a dynamic systems view of this, so if we look at the emergence of life in this paradigm then I would say the problem is to find the space of initial conditions or the analog of the basin of attraction for the emergence of life (the attractor).

And it doesn't matter if our model eventually turns out to be wrong, as long as it is testable, in the sense that it would tell us where, how and what to look for as signs of habitable planets.

[Gomar]

iquestor,

I think you missed the point about the lottery.

If millions of people buy lottery tickets and nobody wins...
the chances of winning are pretty poor if you don't buy a ticket.

-- Jeff, in Minneapolis

I am confused. You have 0% chance of winning if you do not buy lottery tickets; if you do, no matter how small (MM = 1:176m) you do have a chance. Ifcourse, there are non-jackpot prizes as well.
Is it possible somewhere in the universe there is life? Yes. But the probability of it being intelligent enough to be able to travel from planet to planet, inter-solar,
inter-galactic, is small.
There has been no alien visits to Earth in 5million years, thus most likely there never will be.

[Jeff Root]

Gomar,

First, my comment that "the chances of winning are
pretty poor if you don't buy a ticket" was not part of my
comment to iquestor. I unintentionally made it appear
that way by putting the two comments in one post, but
you smushed them together into one sentence!

My second comment was brought to mind by the first.
It was two things:

1) A joke, meant for you to laugh at the fool in the joke,

and

2) An absolutely true story about me.


* * * *

Okay, now... Just because somebody holds a lottery
and draws numbers doesn't mean anyone wins it. That
happens pretty frequently. If it happens over and over
and over, and nobody ever wins, people will get the
idea that the thing is a rip-off, and won't buy tickets.
Maybe eventually somebody *would* win, maybe not.

Is it possible somewhere in the universe there is life? Yes.

Here!

But the probability of it being intelligent enough to be able to
travel from planet to planet, inter-solar, inter-galactic, is small.

Say WHAT?????

It's TOO intelligent! THAT'S the problem! The ET's are all so
blasted intelligent -- all 849 MILLION species of them in the
Milky Way -- that they know better than to waste their time
coming here! Interplanetary travel is expensive and takes a
long, long time. Them aliens know when a trip is worth it
and when it ain't.

There has been no alien visits to Earth in 5million years,
thus most likely there never will be.

True, the last alien visit to Earth was 5 million, 35 years ago,
but that just means the next one is due in only 126,000 years,
give or take a few millenia. Just wait, you'll see. They have
to send somebody round every so often to keep their records
up-to-date.

"Bayesian reasoning" my donkey.

-- Jeff, in Minneapolis

[Daffy]

Is it possible somewhere in the universe there is life? Yes. But the probability of it being intelligent enough to be able to travel from planet to planet, inter-solar,
inter-galactic, is small.
There has been no alien visits to Earth in 5million years, thus most likely there never will be.

You seem to be changing the parameters. I actually agree with this statement (Although I would amend it to "there is no convincing evidence of alien visits to Earth in the last 5 million years). But I can't imagine what would make this little rock unique so that it is the only place intelligent life appeared in the entire universe---almost seems impossible. But due to the distances (in time and space) involved and the cosmic speed limit, I also find it hard to imagine how we would make contact with anyone. I hope we keep trying, though. Who knows?

[IsaacKuo]

Why "5 million years", anyway? That's long before humans even existed. Even if aliens visited Earth one million years ago, there would have been no humans to visit. And even if aliens visited some archaic Homo Sapiens 300,000 years ago, so what? How would we know about it today?

It's only in the last few thousand years that we have historical records to draw from, but how could we tell the difference between an alien visitation and any of myriad stories of fairies or sea monsters or big foot or whatever?

Maybe we could presume that the alien's starship must use some sort of highly energetic propulsion system, so it should have been visible decelerating into the solar system as a "comet". But it's only in the last few centuries that comet observations were measured well enough to tell the difference between a natural comet and something zooming in faster than solar escape velocity.

Without such evidence of a starship, an alien visitation story looks just like any other fanciful story of strange beings.

The bottom line--we have no evidence of alien visits, but this does little or nothing to rule out the possibility of alien visits except for the last few hundred years.

[The Milky Way]

As someone once put it, all our efforts so far to find ET life have been like boiling water and waiting for a lobster to walk into your kitchen. The Universe is unimagineably huge, and we've only observed a tiny, tiny fraction of it in very limited detail.

I have not failed. I've just found 10,000 ways that won't work.
Thomas A. Edison

Think the quote can be used in this context - if we didnt had the SETI program, we would not know that we would fail, would we?

Besides that, everything have a beginning, and SETI is just the start. Hopefully in this century we will come up with a much more advanced way
to SETI.

[The Milky Way]

We know for a certainty that we exist, while we can only speculate on other life. The cartoon is cute but not relevant because of that.

Actually it can be quite relvant. I once read a universal IQ scale of how low IQ is possible and how how its possible.
The scale goes from -4 to +9. regular plants are 1, meateating plants are stunning 2, ants are on 3, and Humans spectacular 5.
So on the IQ scale theres "only" a difference of 2 between human and ants - and the diffirence are gigantic so to speak, and
we dont really show any interest for them ants do we?
Lets say there are a species out there, near us or not, with a IQ scaled 7,8 or 9 - would they really care for us, like we dont care for ants?

What have been written was all said in the article - just thought it would be an interesting point of view here
Ill dump in the article if i can find it - very interesting.

[Blackhole]

Without any evidence to defend the existence of other 'living things', or lack thereof, in the Universe, we are left with what we know about ourselves.

In a basic level of thinking, this is how I break down the thought of other life existing outside of Earth.

Earth appears to have rolled the cosmic dice and lucked out by aligning all of the essential ingredients that are a necessity for life (as we know it). From what I can observe on Earth, life exists in the Universe. It may be a rare combination of many different things (liquid water, carbon, atmosphere, Goldilock zone, Electromagnetic field, the moon, and the list goes on and on...) that allow for life to evolve, but from what we know it has happened once in the Universe. From this, one can conclude that life exists in the Universe and it's at least conceivable that life exists elsewhere in the Universe.

Now if we take what we know about the size of the observable Universe, that is, there are hundreds of billions of star's in the milky way galaxy and many of them with planets orbiting them, and there are hundreds of billions of galaxies. The numbers alone make thinking about the existence of life elsewhere in the Universe perfectly rational.

[Gomar]

But when one person won the lottery, the evidence indicated a better than zero chance that someone else would in the future. And they did.

So if I win tomorrow's $116m MM jackpot, I'll let you know. Even if I hit the 2nd prize of $250k I'll be happy.
I might even donate some $ to SETI or some other research for ET's.

If no one wins, it rolls over to $135m. Given 310m people in the U.S. someone must win eventually.

[kzb]

In science, a negative result can be just as valuable as a positive result. It's not quite that definitive in SETI yet, but the absence of signals does add to the weight of evidence.

There's no ET civilisation in our galaxy. Let's face facts. The Earth is a billion years younger than the average habitable planet, and habitable planets arose in the galaxy about 5 billion years ago.

If the development of a technological civ were in any way common, or even inevitable, the evidence for these ancient civilisations would be obvious. But we don't see any.

[Jeff Root]

There is no reason whatsoever to think that we would be able
to detect any evidence of an ancient, widespread interstellar
civilization. So the fact that we don't see any evidence of one
only tells us that if such a civilization exists, they aren't going
out of their way to make themselves evident to us.

-- Jeff, in Minneapolis

[neilzero]

Humans are sort of intelligent. How can ET identify an intelligent civilization on Earth from one light year away? Perhaps they cannot even tell that our solar system has a third planet, unless they brought a Seti etc system in their space craft about as advanced as we have on our whole planet. The evidence is diminished about one million times at a distance of 1000 light years. Nearly all of our galaxy is more than 1000 light years away = we have scarcely begun a superficial search of our galaxy. We have not even began a search for intelligence in other galaxies, or dimensions. Neil

[kzb]

There is no reason whatsoever to think that we would be able
to detect any evidence of an ancient, widespread interstellar
civilization. So the fact that we don't see any evidence of one
only tells us that if such a civilization exists, they aren't going
out of their way to make themselves evident to us.

-- Jeff, in Minneapolis

Even if this is true, they would be here already. They've had hundreds of millions to billions of years.