Probability of Intelligent Life in Our Galaxy

[marcus]

...
This is as detailed as it gets, far as I know.
http://www.fas.org/sgp/othergov/doe/lanl/la-10311-ms.pdf

My sincere thanks to Chronos for posting this link about Fermi's Question.

there are a lot of eyewitness accounts here
It was 1950 or so
(dated by a newyorker cartoon they discussed)
It was at lunch
He said something like "where is everybody?"
and they all understood and laughed.


And I must confess that obviously it doesn't matter much whther you call it a Question or an objection or a paradox or, even you might say, a Quip.

I think it points out an odd thing for which AFAIK there is no one right explanation. If I yell and rant about this (which I hope doesn't hurt anybody's feelings) it is because of a sense I have that those Quips are the best---the leave it open. they do not prescribe a logical context in which they are always to be interpreted. they are questions pointing in lots of directions.

somebody could write a book with 5 chapters each picturing a different one of Rader's 5 possibilities, one could have a book called "Fermi's question" that explores and visualizes the different possible answers---a SciFi book I would think (unless science has gone out of style in SciFi)

 

[turbo]

Aunt Nettie gave the most convincing explanation of the origin of life on Earth 'way back in 5-3-2001. I'm surprised nobody here has cited her work.

http://www.dearauntnettie.com/archives/archives-0105.htm

 

[turbo]

somebody could write a book with 5 chapters each picturing a different one of Rader's 5 possibilities, one could have a book called "Fermi's question" that explores and visualizes the different possible answers---a SciFi book I would think (unless science has gone out of style in SciFi)

There have been tons of entertaining stories written about these very scenarios, mostly in the '40s through the '60s. In more recent years, the genre has shifted pretty hard toward fantasy, though. People actually refer to "hard" science fiction to denote that the author has tried make his storyline at least conform to possible physics, and not resort to miracles as plot devices.

There have been a number of stories actually that address advances in propulsion technology in the following way: A fast high-tech ship leaves for Proxima Centauri (for instance) and in a matter of months or years, it chances upon a chemically fueled ship that was sent out centuries before and was presumed lost. The crew of the new ship board the old one and find that over the intervening generations, the inhabitants have lost technological knowledge and skills, developed new ship-centered belief systems, forgotten all about Earth and the fact that they are on a colonization mission, etc, etc.

 

[marcus]

Aunt Nettie gave the most convincing explanation of the origin of life on Earth 'way back in 5-3-2001. I'm surprised nobody here has cited her work.

http://www.dearauntnettie.com/archives/archives-0105.htm

thanks for the Nettie link.
this is potentially a great source of information
and I will hereafter keep the link handy at all times

the poem about the man who
was asphyxiated by his own flatulence is inspiring
or expiring as the case may be

 

[Rader]

To continue in the theme of "it's not that simple":
1) If, after another 200 years or so of detailed searching, we find that there never was life on Mars, that would cause a bigger upset to astrobiology than finding evidence of extinct life. Why? Because we know life was well established on Earth within a billion years of its formation; indeed, we can't do any more to directly determine (by fossil evidence) how much earlier - than ~3.5 billion years ago - life flourished on Earth because there are no rocks on Earth older than this (at least, none that could retain fossils). We also know that there is regular exchange of material* between Earth and Mars (and between several other pairs of planets too), and that plenty of earthly bacteria could survive a trip between the two planets. So, if there was a time when the Earth had life and Mars was hospitable to life, then it's highly likely Mars was seeded by Earth. It may be that life originated on Mars and we are all the descendants of martians.

Nereid, what would you say if we found ACDTZ on Mars? This will be the most interesting find, if something `life`is different. The chances would be against this as you say but then if it was so, energy requirements and conditions, would be the only things necessary for life to pop up anywhere. We have only now a short time now to find this out.

 

[kurious]

More intelligent Life will exist where the most time has elapsed relative to where we are in the Milky Way.We have to consider time dilation from special relativity and time dilation from general relativity.So, for our galaxy greatest probability of more intelligent life than us is given by the planet in the Milky Way that has the smallest value
of gravitational field strength + speed relative to us.

 

[Rader]

I don't think it's necessary for all civilizations to develop at the same time for us not to see them. Just that they don't develop very far beyond where we are. No interstellar travel, even by robots, sems to be the requirement.

No, it is not necessary, I agree, it could be 2=3=4. What I want to do is explore the possibility of 5, using facts we know about cosmology. Let us assume we are alone here in the Milky Way. The closest Galaxy is M31 2.2 million light years distant. The diameter of the universe 15,000 million años luz. When we observe a Quasar, we see it in the past, if we could instantaneously be there and look to here, where is the Quasar? We would see the same past, for the Quasar would be the future. So no matter which direction we look in we see the past in the present. If we could be anywhere instantaneously, then we would be nowhere except the present and center of the universe. If the singularity of the Big Bang is to be taken as fact and all evidence to present, seems to indicate that. In one time frame all points are the same, at light speed. The Milky Way and Andromeda are for all practical measurements at the center of this universe, although local measurement indicates 2.2 million light years distant. According to Marcus it would take a 1% of light speed civilization, 10,000,000 years to explore and colonize the Milky Way. The Milky Way is 100,000 light years across. The closest star systems with any possibility of life are much farther than the amount of time we have been trying to locate with light signals, inside the Milky Way. Even if, signals would have to be exact, received, understood and sent back. To do this with M31 we need 4.4M light years. 1% of light speed craft, out of the question, it would be better to stay home and have a beer and wait for subluminal craft to be fabricated.

Putting all this in prospective we just might not notice them yet, because give or take a reasonable amount of time to evolve, there not here yet nor are we there until our technology develops.

In the old west 20 miles was a long way to travel, what was the radius of that traveler’s knowledge?

Maybe 5?

01-We are alone.
02-They have not reached us yet.
03-They consider us ants.
04-They are here, we do not realize it.
05-All civilizations developed at same time, we are and all are at the center of the universe. None are not more advanced, than us, but many could be, equally or less advanced in there technologies.

 

[Entropy]

and that plenty of earthly bacteria could survive a trip between the two planets.

I dought that. It gets over 1000 degrees C when something enters the atmosphere and the blast that threw a rock from Earth to Mars would have killed all organism on it. A meteoric blast is like a nuke.

 

[Chronos]

I dought that. It gets over 1000 degrees C when something enters the atmosphere and the blast that threw a rock from Earth to Mars would have killed all organism on it. A meteoric blast is like a nuke.

Not all meteors explode like a nuke. Most just break into pieces. While it is true the outer surface can get mighty hot, the heat does not conduct very deep into rocky meteorites [the ones most likely to carry stowaways]. Furthmore, fragments from those that break up may not get hot at all. A lot of material was blasted off the surface of planets in the early solar system when asteroid collisions were commonplace [and they are still uncomfortably common these days].

Here is an article about a meteorite found in antarctica that is believed to have originated from mars.

http://www.sciencedaily.com/releases/2001/02/010227073558.htm

Here is a link to the NASA site with a related article and links to info about other meteorites believed to originate from mars

http://nai.arc.nasa.gov/news_stories/news_detail.cfm?ID=85

 

[Nereid]

I dought that. It gets over 1000 degrees C when something enters the atmosphere and the blast that threw a rock from Earth to Mars would have killed all organism on it. A meteoric blast is like a nuke.

Another example of the real universe turning out to be richer than the imaginations of scientists!

It has been known for quite some time that the only part of a meteor that gets really hot is the fusion crust; the insides remain quite cool, say 40C. In fact, carbonaceous chondrites wouldn't be recognisable as such if they were heated uniformly to 1000 C!

More surprising was how easy it is for a large meteor impact on Mars (or the Moon) to accelerate surface rocks to escape velocity, and maintain the integrity of the rock itself. IIRC, it took the recognition of some meteorites here on Earth as being unequivocally martian to convince folk to re-examine their understanding of impact mechanisms; when they did, lo and behold, yes it was easy.

Of course, homo sap, or even a cockroach, would certainly be killed by the acceleration, but bacteria are a great deal tougher. Even if a 'big' critter could survive the blast off, the hard vacuum and radiation of interplanetary space would do it in; not so bacteria, some of which can withstand truly extraordinary dosages, can 'hibernate' inside a rock in a hard vaccuum, and can be revived after dormancy of (hundreds of) millions of years.

 

[turbo]

05-All civilizations developed at same time, we are and all are at the center of the universe. None are not more advanced, than us, but many could be, equally or less advanced in there technologies.

That would be a tough condition to meet. Stars form at different epochs in the life of a galaxy, and who knows when conditions might will arise that would allow life to arise. There may have been civilizations that have already been cut short by their sun going off main sequence and expanding. Their planets could have already been swallowed by their red-giant host. Conversely, there could be lots of planets that "will" be amenable to life in another billion years. Our species may or may not turn out to be very transitory. We have been on Earth for a VERY brief time, and if we do not become more cognizant of our effects on the Earth, we could very well kill our biosphere and ourselves, like a virus that is self-limiting because it kills its host before it gets a chance to infect another host.

 

[Nereid]

Nereid, what would you say if we found ACDTZ on Mars? This will be the most interesting find, if something `life`is different. The chances would be against this as you say but then if it was so, energy requirements and conditions, would be the only things necessary for life to pop up anywhere. We have only now a short time now to find this out.

Please excuse my ignorance, what is 'ACDTZ'?

 

[Entropy]

Not all meteors explode like a nuke. Most just break into pieces. While it is true the outer surface can get mighty hot, the heat does not conduct very deep into rocky meteorites [the ones most likely to carry stowaways].

Any blast that is going to launch a rock from Mars to Earth or visa versa has to have power around that of a nuke, so yes it would be like a nuke. I think more accurately you ment: "rocks can be accelerated by the shockwave [of the blast] into space without being cought in the fireball of the actual impact."

Here is an article about a meteorite found in antarctica that is believed to have originated from mars.

About that, isn't a little weird that the gas in the meteorite matched Mars's atmosphere exactly? The rock is suppost to be billions of years old right (not since it impacted Earth)? Strange that it's atmosphere would be so unchanged.

It has been known for quite some time that the only part of a meteor that gets really hot is the fusion crust; the insides remain quite cool, say 40C. In fact, carbonaceous chondrites wouldn't be recognisable as such if they were heated uniformly to 1000 C!

Err... I find that hard to believe. How exactly does it not conduct heat to the center of the meteorite? Do you have any sources I can go to? I want to learn more on this.

 

[Chronos]

Any blast that is going to launch a rock from Mars to Earth or visa versa has to have power around that of a nuke, so yes it would be like a nuke. I think more accurately you ment: "rocks can be accelerated by the shockwave [of the blast] into space without being cought in the fireball of the actual impact."



About that, isn't a little weird that the gas in the meteorite matched Mars's atmosphere exactly? The rock is suppost to be billions of years old right (not since it impacted Earth)? Strange that it's atmosphere would be so unchanged.



Err... I find that hard to believe. How exactly does it not conduct heat to the center of the meteorite? Do you have any sources I can go to? I want to learn more on this.

Check out the NASA site and report back.

 

[Nereid]

Err... I find that hard to believe. How exactly does it not conduct heat to the center of the meteorite?

In a few words, many kinds of rock are excellent insulators, the meteorite spends only a short time in the air, the fusion crust ablates (carrying off a lot of the heat generated by friction with the air), and volume increases as the cube of the size while surface area only the square.

Do you have any sources I can go to? I want to learn more on this.

See Chronos' reply.

 

[Entropy]

In a few words, many kinds of rock are excellent insulators, the meteorite spends only a short time in the air, the fusion crust ablates (carrying off a lot of the heat generated by friction with the air), and volume increases as the cube of the size while surface area only the square.

Ahhh... I see now, that makes sence.

 

[Rader]

Please excuse my ignorance, what is 'ACDTZ'?

I assumed you would know what I was hinting at, wrong assumption. I was into much of a hurry, hot here 104, off to the beach.

To be more specific.

A, T, G, y C are the letters of the genetic code and representing the nitrogenated bases adenina, timina, guanina y citosina, respectively. These bases together witht the sugar and the phasphate that they are linked to form the nucletoides, the fundamental units of DNA. In each gene the four bases are combined in diverse forms, to create words of three letters that specify which amino acid is necessary for each combination to elaborate a protein.
Nothing you do not know already.

What is 'ACDTZ'? What I was hinting at is, if we find life forms with say five bases to wind the DNA coil, what would it tell us? One additional base and one changed, a totally different combination, from how life evolved on Earth. Whats interesting to me is not if we find life on Mars but if it would be different as I suggest. Whats inside an atom, that when the arrangement of, a group of four bases, forming three letters, in a DNA coil, sprouts life as we know it? Are there other mathematical combinations? I do not expect you to answer this. Suspect to me, that symmetry seems to be universal, there could be other geometrical ways to form a DNA coil, to maybe sprout life.

This will be the most interesting find, if something `life`is different. The chances would be against this as you say but then if it was so, energy requirements and conditions, would be the only things necessary for life to pop up anywhere. We have only now a short time now to find this out.