Sometimes a picture is worth thousands of words

Giorgio · Post by **Giorgio** » Thu Mar 31, 2011 6:30 am

This image is so meaningful I had to post it.

From Astronomy Picture of the Day:
http://apod.nasa.gov/apod/image/1103/Ke ... s_rowe.jpg

Can someone really still believe that we are alone in this universe?

chrismb · Post by **chrismb** » Thu Mar 31, 2011 7:11 am

I believe it is quite possible humans are the only intelligent species in the galaxy, yes. It is not simply that their planet is at just the right conditions for the range of water/organic chemistry that life seems to require, but that the particular history of the planet has lead a path of evolutions just-so, in particular [but not exclusively] the unbelievably fortuitous collision with a like-sized proto-planet to form the earth-moon system (big water tides) and fast rotation [so that life can survive between days and nights]. Another particular feature is the particular abundance of actinides within the core that is just right to maintain a crusted-but-molten-earth, thus a magnetic field and protection from stellar winds.

If you then combine all of that with the temporal issue - viz. that after billions of years of life here that 'intelligent life' has only just emerged, suggests that the probability of life::intelligent_life is diminishingly small, even if the conditions of life are met.

I ask the question in a different way - what would be the probability of all life on earth dying out tomorrow? So I would suggest that if there was no life on a planet one day then the probability of there being some the next is much the same as the inverse of that function. This is because it is not possible for 'one' new organism to come into being. There has to be a 'bio-sphere' of viable organisms that can work within that bio-sphere. It is the total biota on a planet that is 'life', not just the emergence of one organism at a time. So this is why I suggest the probability of life forming is as likely as it is dying, because multiple, interacting species must [die out or] come into being simultaneously, which seems staggeringly unlikely to me.

Skipjack · Post by **Skipjack** » Thu Mar 31, 2011 7:37 am

If you then combine all of that with the temporal issue - viz. that after billions of years of life here that 'intelligent life' has only just emerged, suggests that the probability of life::intelligent_life is diminishingly small, even if the conditions of life are met.

Actually, earth faced several extinction events, that delayed the development of intelligent life by millions, if not billions (ok exaggerated, but could be close to a billion) of years.
E.g. the dinosaurs could have eventually evolved into more intelligent beings. Species like the Dynonychus, or the Velociraptor were highly intelligent and very organized. I remember a paper from some 20 years ago that said that they could have eventually evolved into something called the dinosauroid. A creature of human like intelligence and dexterity.
Now I am no sure whether that is really true, but it remains quite credible that several great extinction events have delayed things on earth quite a bit.
To me it does seem rather unlikely that we are the only intelligent life in this Galaxy, but I do indeed have no evidence that suggests that there is indeed intelligent life out there.
Right now, I am actually glad if there are no other intelligent life forms out there. Earth is in no way prepared for a potential conflict with them.
I do however think that it is very likely that there would be other worlds that are habitable and offer earth like conditions for human colonists.
That would be very desireable as well. In fact, we will need this, if mankind is to survive.

Giorgio · Post by **Giorgio** » Thu Mar 31, 2011 7:47 am

Well, firstly you need to believe that those conditions are all fortuitous and not common in planetary evolution, and this, IMHO, no one can yet prove it or disprove it.

Than why limiting evolution to an carbon/oxygen/water based form? We are already finding life in much harsher conditions on our own planet, so a life form based on another types of chemistry cannot be excluded.

Also I didn't mention Intelligent life, but just life.
If we are looking for Life to communicate with than the "civilization existence time-frame" as you suggested is indeed the most important value, but if we talk only about life than is really less and less important. After all life on this planet is existing from million of years.

Should we talk about intelligent life in the universe I really do not feel that we can consider the Human race among it.
We can probably consider ourselves a smart race, but intelligent? I doubt.

Giorgio · Post by **Giorgio** » Thu Mar 31, 2011 7:54 am

Skipjack wrote:To me it does seem rather unlikely that we are the only intelligent life in this Galaxy, but I do have no evidence that suggests that there is indeed intelligent life out there.

Also to me it makes little sense to think that out of this universe life evolved only on this rock.

If we were an intelligent race we should be busy building space telescope or moon telescope to answer this and other questions, evolve our knowledge and prevent our possible extinction.

Skipjack · Post by **Skipjack** » Thu Mar 31, 2011 8:02 am

I think Carl Sagan once said something like that:
As the only intelligent species in the universe that we know off, it is our duty to find out as much as possible about this universe that created us.
Makes sense to me.

Luzr · Post by **Luzr** » Thu Mar 31, 2011 10:43 am

Skipjack wrote:
If you then combine all of that with the temporal issue - viz. that after billions of years of life here that 'intelligent life' has only just emerged, suggests that the probability of life::intelligent_life is diminishingly small, even if the conditions of life are met.
Actually, earth faced several extinction events, that delayed the development of intelligent life by millions, if not billions (ok exaggerated, but could be close to a billion) of years.

Did it? In fact, development of intelligent life was surprisingly fast, it happened during about 3 millions years, maybe much less (depends on what you consider as starting point...). Conditions for this to happen were stable for at least 100 millions years.

What does this tell you? To me that life in universe might be widespread, intelligence not so much.

Luzr · Post by **Luzr** » Thu Mar 31, 2011 10:50 am

Skipjack wrote: E.g. the dinosaurs could have eventually evolved into more intelligent beings.

Or, and that is funny line of thinking: Perhaps they did. Would we know today? 200 millions of years is long enough to cleanup all traces.

Then, it is possible they actually CAUSED their extinction event.

Or they did not. Or they left earth for space. Or, maybe, they are UFO pilots. Or they are still living on earth, using some sort of masking technlogy. Or among us - hm, thinking about it, perhaps they wrote "V" script to prepare us for them

Skipjack · Post by **Skipjack** » Thu Mar 31, 2011 10:57 am

200 millions of years is long enough to cleanup all traces.

64 million years, not 200 million. They died out 64 million years ago. I suppose, we would still find fossilized remains of the more evolved species. We would most likely also find remains of tools, if there ever was some sort of civilization prior to ours.

They left us the birds though...

Diogenes · Post by **Diogenes** » Thu Mar 31, 2011 1:25 pm

chrismb wrote:I believe it is quite possible humans are the only intelligent species in the galaxy, yes. It is not simply that their planet is at just the right conditions for the range of water/organic chemistry that life seems to require, but that the particular history of the planet has lead a path of evolutions just-so, in particular [but not exclusively] the unbelievably fortuitous collision with a like-sized proto-planet to form the earth-moon system (big water tides) and fast rotation [so that life can survive between days and nights]. Another particular feature is the particular abundance of actinides within the core that is just right to maintain a crusted-but-molten-earth, thus a magnetic field and protection from stellar winds.

If you then combine all of that with the temporal issue - viz. that after billions of years of life here that 'intelligent life' has only just emerged, suggests that the probability of life::intelligent_life is diminishingly small, even if the conditions of life are met.

I ask the question in a different way - what would be the probability of all life on earth dying out tomorrow? So I would suggest that if there was no life on a planet one day then the probability of there being some the next is much the same as the inverse of that function. This is because it is not possible for 'one' new organism to come into being. There has to be a 'bio-sphere' of viable organisms that can work within that bio-sphere. It is the total biota on a planet that is 'life', not just the emergence of one organism at a time. So this is why I suggest the probability of life forming is as likely as it is dying, because multiple, interacting species must [die out or] come into being simultaneously, which seems staggeringly unlikely to me.

I agree. Every year (it seems like) I run into information that indicates we are Unique and that the chances of a repeat (or even functionally similar) are unlikely.

I've read that Evolution is boosted by extinction events presumably caused by collisions of meteorites. I've read that Jupiter protects the planet from CONSTANT bombardment by acting as a sort of blocker and diverter for planet Earth.

I've read that the moon stabilizes the planets rotation, and without it the whole thing might be a deep freeze, I've read that the Earth's magnetic field pushes away most of the damaging particles streaming at us.

I've read that so many serendipitous and peculiar characteristics of this particular solar system must ALL occur just to make life on this planet possible, and that the odds of exactly the same sort of beneficial arrangements are highly unlikely in most Solar systems.

It's sort of the Anthropic principle on a smaller scale.

But yeah, I agree with your assessment.

rjaypeters · Post by **rjaypeters** » Thu Mar 31, 2011 3:35 pm

Giorgio wrote:Should we talk about intelligent life in the universe I really do not feel that we can consider the Human race among it.
We can probably consider ourselves a smart race, but intelligent? I doubt.

Except for the readers of this web-page, of course.

To paraphrase: If it's just us, it seems like an awful waste of space.

I subscribe to the statistical argument*: we have only looked at the merest specks of dust surrounding what we grandiloquently call "our" speck of dust. Even with the astronomical improbabilities listed above and others, the available volume in our** galaxy makes, I think, it likely we are not alone as intelligent beings.

However, I think the real problem is time. When will the intelligent life develop? Will the development of other intelligent life overlaps ours? If so, will we be able and willing to contact each other?

Edit: Oh, and will we change so we are no longer interested in Contact when another intelligence species develops?

*Derived from the Drake equation and related concepts.

**More grandiloquency!

seedload · Post by **seedload** » Thu Mar 31, 2011 3:57 pm

Diogenes wrote:
chrismb wrote:I believe it is quite possible humans are the only intelligent species in the galaxy, yes. It is not simply that their planet is at just the right conditions for the range of water/organic chemistry that life seems to require, but that the particular history of the planet has lead a path of evolutions just-so, in particular [but not exclusively] the unbelievably fortuitous collision with a like-sized proto-planet to form the earth-moon system (big water tides) and fast rotation [so that life can survive between days and nights]. Another particular feature is the particular abundance of actinides within the core that is just right to maintain a crusted-but-molten-earth, thus a magnetic field and protection from stellar winds.

If you then combine all of that with the temporal issue - viz. that after billions of years of life here that 'intelligent life' has only just emerged, suggests that the probability of life::intelligent_life is diminishingly small, even if the conditions of life are met.

I ask the question in a different way - what would be the probability of all life on earth dying out tomorrow? So I would suggest that if there was no life on a planet one day then the probability of there being some the next is much the same as the inverse of that function. This is because it is not possible for 'one' new organism to come into being. There has to be a 'bio-sphere' of viable organisms that can work within that bio-sphere. It is the total biota on a planet that is 'life', not just the emergence of one organism at a time. So this is why I suggest the probability of life forming is as likely as it is dying, because multiple, interacting species must [die out or] come into being simultaneously, which seems staggeringly unlikely to me.

I agree. Every year (it seems like) I run into information that indicates we are Unique and that the chances of a repeat (or even functionally similar) are unlikely.

I've read that Evolution is boosted by extinction events presumably caused by collisions of meteorites. I've read that Jupiter protects the planet from CONSTANT bombardment by acting as a sort of blocker and diverter for planet Earth.

I've read that the moon stabilizes the planets rotation, and without it the whole thing might be a deep freeze, I've read that the Earth's magnetic field pushes away most of the damaging particles streaming at us.

I've read that so many serendipitous and peculiar characteristics of this particular solar system must ALL occur just to make life on this planet possible, and that the odds of exactly the same sort of beneficial arrangements are highly unlikely in most Solar systems.

It's sort of the Anthropic principle on a smaller scale.

But yeah, I agree with your assessment.

Limit it to the galaxy then I agree too - for additional reasons. If abundant intelligent life exists in the galaxy then it must exist far in advance of our existence. Say a billion years. Given a billion year head start, then an intelligence at our level would have spread quite readily through the galaxy. We would see signs of it. We do not. Therefore, it doesn't exist.

At a universal scale, I tend to think it is probably out there. 100's of billions of galaxies with 100's of billions of stars. 50,000,000,000,000,000,000,000 or so is a lot of stars.

Just my two cents.

Luzr · Post by **Luzr** » Thu Mar 31, 2011 4:56 pm

Skipjack wrote:
200 millions of years is long enough to cleanup all traces.
64 million years, not 200 million. They died out 64 million years ago. I suppose, we would still find fossilized remains of the more evolved species. We would most likely also find remains of tools, if there ever was some sort of civilization prior to ours.

Are you sure? My understanding is that fossilized remains we are able to find today are just random samples of very very long time period.

About tools, well, maybe some materials could keep the form for such a long time. But not many. Iron turns into rust. Glass losts its shape. Stone buildings broken by erosion....

But of course, it is mere funny speculation. I believe that the correct assesment is that intelligent life is very rare even if life itself is common.

KitemanSA · Post by **KitemanSA** » Thu Mar 31, 2011 6:22 pm

Luzr wrote:
Skipjack wrote:E.g. the dinosaurs could have eventually evolved into more intelligent beings.
Or, and that is funny line of thinking: Perhaps they did. Would we know today? 200 millions of years is long enough to cleanup all traces.

Please tell me folks, what is the physical trace of "intelligence"? For all we know there have been 50 sapient species on this planet, only one of which chose to go the "technology" route. What trace would a race of a-technical genius philosophers leave?

rjaypeters · Post by **rjaypeters** » Thu Mar 31, 2011 6:53 pm

seedload wrote:Given a billion year head start, then an intelligence at our level would have spread quite readily through the galaxy. We would see signs of it. We do not. Therefore, it doesn't exist.

Yes, the absence of evidence is evidence of absence argument. The irony is you are not alone in making it.

When looking at artifacts from a very old civilization, would we recognize what we were looking at?