Trillions of Earths

[CraigS]

Originally Posted by bojan

Your line of thinking (and Bert's) is more or less the same as mine
However, to satisfy the scientific processes and procedures (excuse me for this "managerial talk") we have to go on searching for evidence, direct and indirect., of course.

Hmm… some might say that the search for evidence is to satisfy human curiosity.

Having said this, I do believe that there is an undeclared scientific theory of the existence exo-life. And this is under investigation.

Strange, because formally, a theory is an explanation of an observed phenomenon. But we don't have any observations yet, (outside Earth).

The other interesting aspect to this, is that this approach will never be able to reveal the ultimate 'truth' of of it all, because of the problem of induction, (it only takes one negative example to destroy a theory), and you can't examine all examples of this phenomenon, throughout all time and space.

It'll never be a scientific law, because a law is a phenomenon which has been observed many times, and no contrary examples found, so then it is accepted as a universal phenomenon .. a law.

So why all the talk of scientific process?


Perhaps a straw-man (hypothesis) ?

Amazing how science is warped around beliefs in disguise !

Cheers

[Robh (Rob)]

Originally Posted by CraigS

The problem here is that whatever processes which brought DNA/RNA, viruses and cells into existence on Earth (from chemical 'soups'), should also operate somewhere else, within the vast sample space.

This thinking then leads to the opinion that the Universe is teeming with life.

But the permutations and combinations of environmental conditions, necessary to support the processes leading to a viable candidate outcome, may actually turn out to be of more significance and impact on a single successful outcome, than the mere presence of the right compounds (eg: water), and processes, which have operated here on Earth.

We presently pay very little attention to these aspects. Once again, we have little/no empirical evidence underpinning these considerations, outside of the terrarium called Earth.

Craig, I agree with your assessment here.

When it comes down to it, the extrapolation of the life is here to the life is everywhere hypothesis is somehow based on the cosmological principle. That the chemistry and conditions here are repeated throughout the Universe. But does similarity of chemistry and conditions necessarily produce life?

Just how finely balanced are the conditions that allow life to originate? Are the very beginnings of life, the transition from inanimate to animate, just a fluke of chemical interactions and environmental conditions?

It is interesting that life on Earth is based on a DNA (or RNA) model of 4 chemical bases. This interconnection between living things implies to me a very narrow window of opportunity for the origins of life. Why haven't we also evolved jungles full of creatures based on a very different model altogether? Is this the only model that the Earth could fluke given the set of conditions at the time or was it just the most efficient model? Are we assuming that life elsewhere will also be based on the DNA/RNA model? If so, why does this happen?

I welcome any of the biologists to give their opinions as I've reached my level of incompetence on this issue!

Regards, Rob

[CraigS]

Yes Rob.

Good questions. I'd like to hear from the molecular-biologists on these ones as well.

Why haven't we also evolved jungles full of creatures based on a very different model altogether? Is this the only model that the Earth could fluke given the set of conditions at the time or was it just the most efficient model?

Evolution-by-natural selection may have taken 'care' of the other models.

As interesting as the possibility of exo-life is, equally interesting is the question of how would terrestrial DNA/RNA survive or adapt, on an exo-planet. We could learn a lot more about our own DNA/RNA and natural selection, if we plonked some on Mars to fend for itself.

But that would be pollution !

Take a look at this one.

The survival of so many of the bacteria in such a hostile environment with no oxygen adds weight to the hypothesis that microbes carried in meteors and meteorites could seed life on other planets or moons.

There ya go .. bacteria doesn't even need oxygen !!

I agree with Bert .. we know almost zip about what our own life needs to survive/develop !

So what does this say about increased/decreased chances of life with increasing numbers of exo-planets discovered ?

Cheers

[mswhin63 (Malcolm)]

Originally Posted by Robh

I don't take the view that life is inevitable or not inevitable in the Universe at large. There is just no statistical evidence to support either view. The Earth may be a unique sample of one.

Regards, Rob

I have to totally agree, all the findings on earth only provide a statistical reference to earth only. With that reference point all we can do is to say is allow life to exisit in more potentially toxic locations but still have not found these potential toxic locations.

We only need to do a single finding on another planet or a moon of a planet to completely change everything. A base number on a single world is not the basis for statisitical calculations for other worlds.

The first point of interest would be to find life on an active planet, maybe Triton which shows a lot of activity etc. Once we have find life on another planet then we have a second point of statisical calculation and then can justifiably make the claims.

This will obviously take a long time although they are developing a rover for one of the moons of Saturn already to pentrate one of the icy moons.

[CraigS]

So, further to my post #41, which tends to imply that the belief in exo-life is just that .. a human idea, (or belief), as opposed to a scientific one, I offer 'Logical Reasoning' as an alternative interpretation:

There are three kinds of logical reasoning: Deduction, Induction and Abduction.

Deduction means determining the conclusion. It is using the rule, and its precondition, to make a conclusion.

Induction means determining the rule. It is learning the rule, after numerous examples of the conclusion, following the precondition.

Abduction means determining the precondition. It is using the conclusion and the rule, to assume that the precondition could explain the conclusion.

Using these techniques, one could easily argue the case for, or against, probable exo-life. These arguments would appear to be reasonable, perfectly logical statements, based on the available evidence.

However, logical arguments can also be made entirely independently from the available empirical evidence (or absence thereof).

Logical, but not scientific !

Errors in logic can be made by using Abductive logic, also.

Interesting.

Cheers
PS: I've seen a few examples of these techniques, lately.

[avandonk]

Something I just remembered reading about some years ago and discussing with my colleagues.

Would you believe bacteria in solid granite deep in the earth! They replicate about once every hundred or thousand years. Their biomass could be greater than what is on the surface!
Is this alien enough for you?

Here
http://nai.nasa.gov/news_stories/news_print.cfm?ID=46

and here
http://aem.asm.org/cgi/content/abstract/76/14/4788

There is far more if you google


Were these bacteria subducted eons ago by tectonic plate movements? Or did they originate there?

I will quote the line all scientists use at the end of any paper 'further work is needed'.

Why all life on earth uses the same template for DNA, RNA and proteins etc. is for one simple reason if you have a different system you cannot exploit other life for food.

Even in the eighteenth century scientists knew that there had to be enzymes that broke down all different forms of organic matter originating from life. Say that flies legs were impervious to breakdown then we would be knee deep or higher in flies legs.

Until a bacteria evolves to break down the plastics we are polluting the earth with, we will end up with plastic everywhere. It is already a major pollutant in the oceans and responsible for countless deaths of sea life.

I do agree we have no proof of any life outside our Earth. Consider though how many exoplanets did we know of twenty years ago, zero?

Opinion or hypotheses count for nothing but at least it opens the mind to look for the evidence.

Titan looks like a good place to start.

Bert

[CraigS]

Hmm ..
Very interesting there, Bert.

Now I know what you meant when you said (about exo-life):
"Fortunately they are too far away to hurt us" !! Food source, eh .. hmm…

I am hesitant to bring it up, but Tom Gold had a theory about bacteria living deep inside the Earth. He wrote a book called "The Deep Hot Biosphere". I think he theorised that the bacteria were living on hydrocarbons which were continually being generated by deep primordial processes, which have continued since the formation of the Earth. Fascinating read. I think it was created at a time to counter the 'peak oil' hypothesis. I had a thread with Carl on this one. I don't think geologists like Gold's theory.

Titan, eh ? Yep .. I threw that one into our answers to the school kids about possible places where life might be able to exist, (Gold's theory actually predicted it … and Titan's environment !). I'm surprised you wouldn't choose Enceladus or Europa, though, (because of the liquid water presence).

Interesting.

Cheers

[avandonk]

"I'm surprised you wouldn't choose Enceladus or Europa, though, (because of the liquid water presence)."

CraigS



Craig you are of course quite correct. I was just pointing out that a look closer to home was possible. I did not have the facts that you put forward in my head as I cannot know everything. What would we make of life if found on all these possibilities? If it has the same template as life on Earth would it prove seeding of life by comets/asteroids? If the template is different it would indicate that life is everywhere there is liquid water.

Remember that 1950's science fiction movie where the aliens had a book called "To Serve Man". Too late did people find out as they were being spaceshipped out that it was a cookbook!

Bert

[CraigS]

Originally Posted by avandonk

What would we make of life if found on all these possibilities? If it has the same template as life on Earth would it prove seeding of life by comets/asteroids?

Hmmm .. perhaps it might prove what we'd like to prove .. "wherever there is water, there is life" .. but all it really would show is that there's another moon in our solar system, which has life we recognise .. and has water.

If the template is different it would indicate that life is everywhere there is liquid water. Where did it come from ? Panspermia?? Necropanspermia ?? The questions are endless !

would we recognise it as life if the template was different? I guess it depends on just how much different. Who knows ?

Remember that 1950's science fiction movie where the aliens had a book called "To Serve Man". Too late did people find out as they were being spaceshipped out that it was a cookbook!

Bert

Ha !!
Haven't seen it … but I like the idea !!


Cheers

[jenchris (Jennifer)]

Firstly I think it a bit arrogant to even surmise we're the only lifeform with IQ above 10.
A million monkeys typing for a million years will produce the complete works of Shakespeare (along of course with most other books and novels and possibly quite a few good new ones.)

So RNA/DNA would simply happen given a certain set of values in any situation that warranted it.

65 million years ago, the saurian empire was reduced to ashes.
Who is to say that intelligent saurians would not have evolved in the ensuing period - maybe alongside mammalian proto-human - if we had not been subjected to a comet strike (if that was what put paid to the scaly ones.)
I read a book about it once - West of Eden - great concept.
Wherever the chance for life exists, life will exist in whatever form and style that will allow progenation.

"It's life Jim, but not as we know it." Probably the basis of all of our yearning for the stars. We're boldly going and no one will ever stop us.

[CraigS]

Originally Posted by jenchris

Wherever the chance for life exists, life will exist in whatever form and style that will allow progenation.

Interesting that this thread has generated such opinions.

I'm reminded of one of the few valuable comments on this topic:

Confusion exists between statistics and empirical data. There is no empirical data. Statistics do not reveal truths. Even a probable outcome is not a dead certainty.

Originally Posted by jenchris

"It's life Jim, but not as we know it." Probably the basis of all of our yearning for the stars. We're boldly going and no one will ever stop us.

And going there is the only way to find out !

Cheers

[avandonk]

I am reminded of simple computer programs that are allowed to evolve by combining the most successful ones. Very quickly we get programs that can mimic life.

It is not a throw of the trillion dice every time! It is then weeding out of the useless numbers after one throw, and throw again with loaded dice.

Our weakness as humans has turned into our ultimate strength. We are born helpless and lacking very few survival skills and depend on our parents and others for initial survival and teaching us these same skills as we get older. It is this long process that has led to our dominance of the planet.
We can evolve quicker than our genes. Our knowledge is stored in books and more lately on line.
I just wish that more people would learn the lessons that are stored in the multitude of these books rather than relying on the scratchings of goat herders in one book that they call holy.

Bert

[Robh (Rob)]

Originally Posted by jenchris

A million monkeys typing for a million years will produce the complete works of Shakespeare (along of course with most other books and novels and possibly quite a few good new ones.)

Hi jenchris,

Good to have your input.
A lot of the arguments run along this line ... that life has to eventuate given enough stars and enough time.
Your statement about the monkeys is going to be hard to assess.
An interesting point and seemingly feasible. But I wonder?
I'll get back to you when I get some numbers.

Regards, Rob

[CraigS]

Originally Posted by avandonk

I am reminded of simple computer programs that are allowed to evolve by combining the most successful ones. Very quickly we get programs that can mimic life.

Dawkins had one of these .. 'Weasel' I think he called it. Neat stuff.

Can't help but think that it had a copious dose of Post #45 in it .. (Deduction, Induction, Adbduction) … otherwise it would probably crash every time !

Still, as far as a model to counter an attack is concerned, I think it did quite admirably.



A Michio Kaku documentary aired recently, in which a computer program was created, which started out with animated stick figures. Their task was to develop into upright walkers, which they eventually did.

Can't help thinking this program also had a big dose of irrefutable logic in there, as well.



Cheers

[Robh (Rob)]

Hi all,

The statement was made that ...
A million monkeys typing for a million years will produce the complete works of Shakespeare (along of course with most other books and novels and possibly quite a few good new ones.)

To our perception, the statement appears entirely feasible. But is it? I didn't really know.
Being curious, I thought the problem was worthy of some analysis. If nothing else, it would illustrate the complexity of information.

To reduce the labour involved, I decided to just download a text version of one of Shakespeare's plays "As You Like It". It has the famous line that goes "All the world's a stage". I then counted the number of each character a, b, c etc in the text. No, I didn't sit there and count each individual character! You can use find and change, replace a with a, b with b etc. and it tells you how many it's replaced. There was 110 pages, 22959 words and 123539 characters, which also includes things like commas, semi-colons and spaces. I accounted for every character bar 34 of them but didn't waste more time trying to track these few down. Conservatively, I divided out 34! (that's factorial) in the end just to be sure.

If every character were different, there would 123539! different arrangements of all the characters. That's about 1.06 x 10^575387.
However, there are 7109 letter a's, 1359 letter b's, letter 1913 c's etc. So this reduces the number of possible arrangements to
123539!/(7109! x 1359! x 1913! ...).
After some hours of computation (am I crazy), the number of possible random arrangements came to about 6.9 x 10^160016.
As a comparative reference, the number of stars in the observable Universe is estimated at 10^22 and the number of atoms at 10^80.

So, lets get one monkey typing 1 character per second for a year.
That increase our chances to 1 in 2.2 x 10^160009 of ending up with Shakespeare's classic.
If you put a trillion (10^12) monkeys on a planet around every star in the Universe (just play the game) and let them type for a billion years, that increases your chances to one in 2.2 x 10^159966.

Even a computer operating at 10^15 calculations per second won't put much of a dent in this figure.
Result ... pretty much impossible. Gone to rest my brain.

Regards, Rob

[CraigS]

OMG !!!

Such dedication !! Such tenacity !!

Rob for the next Newton Medal Prize !
(the maths equivalent of the Nobel Prize! … sorry Steven .. he pipped you at the post !).

Mind you, Jennifer's statement had me go into recall, as I have read this same 'story' somewhere, sometime, also. I just can't remember where.

Just goes to show how easy it is to make statements and how easily they become embedded in our collective consciousness as 'truisms'.

Good onya Rob.

Cheers
PS: So, the corollary to the assertion was: "So RNA/DNA would simply happen given a certain set of values in any situation that warranted it." Hmmm …. (??)

[Robh (Rob)]

Originally Posted by CraigS

Mind you, Jennifer's statement had me go into recall, as I have read this same 'story' somewhere, sometime, also. I just can't remember where.

Craig,

Just came across this. Oh, well!
At least it supports the order of magnitude of my results.

http://en.wikipedia.org/wiki/Infinite_monkey_theorem
Under the heading Probabilities

Regards, Rob

[CraigS]

Ha Ha

I knew I'd read about it before … 'twas in The Blind Watchmaker by Dawkins!

The Wiki article says:

Evolutionary biologist Richard Dawkins employs the typing monkey concept in his 1986 book The Blind Watchmaker to demonstrate the ability of natural selection to produce biological complexity out of random mutations. In a simulation experiment Dawkins has his weasel program produce the Hamlet phrase METHINKS IT IS LIKE A WEASEL, starting from a randomly typed parent, by "breeding" subsequent generations and always choosing the closest match from progeny that are copies of the parent, with random mutations. The random choices furnish raw material, while cumulative selection imparts information.

Just like I said previously, this program involves hard-coded logic to make Dawkins' point.

There are lots of 'ins and outs' behind this truism, it seems. Everyone wants to interpret it to prove something … for and against. The trap seems to be in attempting to use it as 'proof'.

These words still apply: "Statistics do not reveal truths. Even a probable outcome is not a dead certainty". Nor is an improbable outcome, a dead certainty.

It would seem that one cannot use the typing monkeys analogy, to state anything with absolute certainty .. for or against.

Until we find a highly intelligent monkey !

(Perhaps that was Shakespeare )

Cheers

[ngcles]

Hi All,

Hmmm ... all very interesting and educational. Just to set a few things straight ...

Though I am personally of the opinion that intelligent life in our galaxy is very, very rare (ie as I said in the other thread and probably <10 and tending towards very small one digit numbers) out of its 300 to 400-odd billion stars, yes of course we should be looking earnestly!

A find of any life-form (past or present) on Mars while very interesting is not particularly significant for gauging the likely extent of life elsewhere in the Milky Way. We know that it is quite possible for simple bacteria and archaea to make the journey inside rocks that have been blasted off the surface by meteor/comet impacts. I think I read somewhere that Earth receives a couple of kg of Mars every year -- and it works in reverse. Viable bacteria/archaea inside a suitable rock could survive for many tens or thousands of years to land somewhere else and colonise that place. If we found evidence of simple life on Mars, fact is, it is too easily transferred either way for us to easily conclude it arose on both bodies independently without other evidence.

The case for Jovian or Saturnian moons is substantially different. There is virtually no mechanism to transport life from Earth or Mars there or vice-versa. If evidence were found there, then that certainly raises the probability that simple life is ubiquitous in our galaxy (and therefore the Universe as a whole). Obviously this is both where and why we should look. I support the idea of searching wholeheartedly. If it is there does it affect my philosophical or world-view – no. If it isn’t there does it affect my world-view – no. If it is there does it increase the probability that intelligent life exists elsewhere – I think a little bit, but not by that much.

It almost amounts to a massive leap of faith to conclude that if we find bacteria/archaea within the oceans of Europa, that intelligent life is similarly ubiquitous. Plants and animals need a much, much, much narrower range of stable conditions to even stand a slight chance. The first bacteria/archaea arose here at about 800 million yeas after the formation of Earth -- a quite long time. It may have happened a little earlier than this but there is no evidence of it.

The bacteria/archaea of today are essentially unchanged compared to those found in the fossil record from 3.5 billion years ago. They are extremely simple creatures who are robust, hardy and can survive in a wide-range of environments – high pressure, low pressure, high/low temps, underground, underwater, chemicals etc etc. But in themselves they will never learn to mix concrete or sign complicated insurance forms.

It took nearly another 3 billion years till we reach the point where there was (merely) multi-cellular life and then another 750-odd million years before we turn up. During that time there were/are literally tens if not hundreds of millions of species and varieties that did not develop intelligence. We are the only one that has managed the trick and we should never have succeeded according to the biologists (ask Charley Lineweaver UNSW astro-biologist). If you can, take in one of his talks on astro-biology and you will come to appreciate that if we (humans) suddenly die out we won’t be replaced by super-smart kangaroos, gorillas or dolphins in a hurry, or much more likely, ever.

If the eventual development of an intelligent species given favourable conditions is common or even fait’ du complete if you start just a few viable organisms, why weren’t/ aren’t there more intelligent species on Earth? Apart from we humans, even the most advanced and “intelligent” creatures in both present day in the fossil record show no sign of becoming more “clever” during the very long stages of their existence as a species – ie the smartest kangaroos today do not have more developed brains than those from many millions of years ago.

The dinosaurs were the “master-race” of this Earth for hundreds of millions of years yet none of them managed it either. Why? On the available evidence (ie without invoking wishful-thinking or speculation that “life may be different elsewhere”) the only conclusion you could reach is that intelligence is an exceptionally rare trait among advanced multi-cellular creatures – in fact it is so rare that in 3.8 billion years of our history and 10s or 100s of millions of species only one creature made the grade – and we shouldn’t have! If you don’t call that flukey, then what is?

/cont Pt 2 ...

[ngcles]

cont ...

But that’s just the icing on the cake! Before you even get to that stage, in order to have conditions suitable for frail, intelligent creatures, the evidence (we have a sample of one as the example, and again without speculative or wishful thinking) indicates you probably have to have the right sort of galaxy in the right sort of cluster. Not as common as you might think! The star has to be of at least moderate to solar metallicity (otherwise there isn’t enough material to make substantial terrestrial planets) and within certain limits on mass. Probably no more massive than say F6 to make it long-lived enough or no smaller than about G6 to make the habitable zone around it distant enough to prevent tidal locking of rotation of any terrestrial planet in the habitable zone. The star will also need to be within the galactic habitable zone and have a circular or near circular orbit. It is also preferable that (like our Sun) it orbits roughly in resonance with the spiral pattern of the galaxy.

The terrestrial planet orbiting such an unlikely star will also probably need conditions that include: a large moon (have you considered how unlikely the event that made our Moon was?), a geo-dynamo to maintain a magnetosphere and prevent evaporation of our atmosphere, the right (and stable) obliquity, be moderately fast rotators (too fast and the weather’s too unstable/extreme, too slow and we freeze to death at night), the right balance between continental crust and ocean plus plate-tectonics. Then it has to be in that habitable zone for a looooooong period of time. The other planets in the system will need stable circular orbits (again, very unlikely on the sample we’ve discovered) and we also need a gas-giant(s) at the right place to act as both a policeman and to direct enough comets at the right time our planet needed to obtain a water reservoir.

It is my opinion that the culmination of all these pre-requisites (and conditions) in one place for sufficient length of time is a manifestly unlikely event. But, we do have 400-odd million stars in our galaxy to pick from. Even so, for all these things to intersect and produce a planet that is habitable by frail, intelligent creatures over long periods would have to be seen as an exceptional rarity. But once you’ve got that suitable home, then and only then do all the further improbable (and time consuming) events that ultimately produce and support a frail intelligent species come into play.

Please don’t see my opinion as discounting yours (whatever it may be) they are all opinions because we have a very distinct lack of empirical evidence that bears directly on the question of whether intelligent life is ubiquitous. By comparison, simple life (bacteria/archaea) is likely to be much more common in our Milky Way (because it is both simpler and a lot less picky) but still very much a rarity compared to the number of stars present.

On that basis, again the way I see it, intelligent life is likely to be exceptionally rare and maybe even singular in our galaxy. Agree or disagree with my opinion (that for the last time I point out that I'm not passing-off as “fact”) by all means, but your view like mine is similarly an opinion.

It is an exceptionally interesting topic.



Best,

Les D