The Fermi Paradox: Are We Alone in the Universe?

[emc2cracker]

Rare Earth or rampant life?

I remember watching Carl Sagan's Cosmos and seeing the equation for life in the universe for the first time. It really made me wonder if indeed we might find some form of life at one of our nearby extra solar systems. But I remember even then wondering if the equation wasn't lacking in parameters.

The first question I had was on the number of stars, surely not just any star would be capable of supporting life. The only example we have is our sun, and it seems that the percentage of stars that are like our sun would be but a fraction of the number of stars in the universe.

Then rare Earth theory came out and I couldn't even imagine the parameters that they came up with. A brief summary:

Galactic Habitable Zone:

Radiation from the galactic center is bad for life, but heavy elements are essential for life. So basically every galaxy has its own habitable zone much like a solar system would.

Right kind of star:

Hot stars have a short lifespan that would not favor evolution of life, red dwars have a habitable zone that would put the planet in a tidal lock. It is thought that this would not favor evolution of life either. I quote from wikpedia article on rare earth:

" Rare Earth proponents argue that the stellar type of central stars that are "just right" ranges from F7 to K1. Such stars are not common: G type stars such as the Sun (between the hotter F and cooler K) comprise only 9%[14] of the hydrogen-burning stars in the Milky Way."

Right planetary systems:

A system that supports life obviousely cannot have a large gas giant with a crazy orbit or an orbit in the habitable zone because it would probably fling any potential planets capable of supporting life out into space. But recent discoveries have shown that gas giants don't necessarily shield inner planets from asteroid impacts, so basically gas giants aren't essential for life so long as they are either not there or not in a conflicting orbit.

Large moon:

It is also thought that our moon was essential in life on our planet, making planets with large moons like ours more favorable for life conditions. But it seems our moon maybe a very very rare occurence. Our moon is essential for seasons and stabilizing our Earth rotation. But then again it maybe our moon is not as rare as rare Earth proponents think, after all in our solar system has 1/3 of Earth sized planets developing a large moon.

The other parameters are not so cut and dry but I will post this link to wikpedia article on rare earth: http://en.wikipedia.org/wiki/Rare_Earth_hypothesis

If this theory is correct or even close it may seem that the probability that there are other intelligent life forms in the universe is very low. It may be that we are the first life forms to evolve to intelligence in the universe! Can you imagine what kind of responsibility we would have in that instance? It seems to me if we are all there is that its our duty to colonize and spread life throughout the universe.

I do not understand why we are not building "project orion", the craft that was proposed in the 60's to reach the nearest star systems using pulse nuclear detonations. Such a craft could reach maybe 5% of the speed of light using current technology, far more if we could harness antimatter explosions in a feasible way. The sooner we reach extra solar systems the sooner we will know just how rare life may be or not.

Can anyone here weigh in on this and help me fomd this may be wrong in some of its assumptions? To me this is a very depressing theory.

Thanks

 

[mgb_phys]

I do not understand why we are not building "project orion", the craft that was proposed in the 60's to reach the nearest star systems using pulse nuclear detonations.

I think it was the idea of a launch that involved detonating 100s of atom bombs over Florida, or the possible effects on real estate values of 'doing a Challenger' with a craft with a couple of gigatons worth of thermo-nukes on board.

 

[emc2cracker]

I think it was the idea of a launch that involved detonating 100s of atom bombs over Florida, or the possible effects on real estate values of 'doing a Challenger' with a craft with a couple of gigatons worth of thermo-nukes on board.

Well frankly the idea of launching that way off the surface of the Earth is insane, I have given no thought to it though I know it was suggested back then. But building such a craft in orbit is feasible, assembling the bombs in space could be done as well though I think its not necessary. There could be a system of checks and safety features to launch the bombs into orbit without the risk of detonation or contamination using rockets instead of the shuttle would be far safer. In any case I think its worth the risk to be on our way to the next star system don't you?

But I think the nuclear space treaty is the killer of this idea. Though I think its silly to imagine that we may somehow poison space with radioactivity by traveling this way. Though I agree when approaching any extra solar system we would have to exercise caution and make sure we are leaving our trail out of the way of potential life bearing planets.

 

[mgb_phys]

IIRC the design weighed several 1000tons, and had a reaction plate that was a 2000 ton lump of nickel - getting that lot into LEO would be 'challenging'. Typical launch costs are about $5000/kg

Building bombs that don't go bang accidentally is easy - but you are still planning to lift a few 10,000kg or Pu into LEO, an accident that aerosoled that over Florida - whilst possibly raising the average standard of the US - wouldn't do much for the local politician's chances.

Seriously though - the real way to do galactic scale exploration is self replicating robots, look up von Neumann machines.

 

[emc2cracker]

IIRC the design weighed several 1000tons, and had a reaction plate that was a 2000 ton lump of nickel - getting that lot into LEO would be 'challenging'. Typical launch costs are about $5000/kg

Building bombs that don't go bang accidentally is easy - but you are still planning to lift a few 10,000kg or Pu into LEO, an accident that aerosoled that over Florida - whilst possibly raising the average standard of the US - wouldn't do much for the local politician's chances.

Seriously though - the real way to do galactic scale exploration is self replicating robots, look up von Neumann machines.

Ok we are getting way off topic lol, I'll concede I shouldn't have brought methods of space exploration into the topic of rare Earth theory. However we get to the nearest starts we need to get there! Its easy to dismiss ideas that we will never have the benefit of, any exploration mission to the nearest stars would only benefit our grandkids at the most or great great grandkids.

But really how we find out if Earth is that rare is irrelevant to the question "is Earth really that rare?"

 

[slide_Rules]

But really how we find out if Earth is that rare is irrelevant to the question "is Earth really that rare?"

An educated guess: In ~50 years, we should have enough data about the nature of extra-solar planets to do some sort of statistical analysis.
Assuming steady technological progress, any reasonably close (50 ly?) Earth like planets should be detectable.
My guess is that intelligent life is very rare - but simple microbes may be much more common.

 

[Chronos]

'Only' 9% of the stars in the milky way are class G? - 9% of ~200 billion is 'rare'? The 'rare earth' argument is rather flimsy. We already know that moderate and lower luminosity stars constitute the majority of all stars, and stars without planets are the exception, not the rule. It is true that planets orbiting a red dwarf stars in the habitable zone would become tidally locked, but, how certain are we this would occur before life could arise and evolve? An intelligent species could develop substantially technological capabilities in a few million years.

The vastness of space is the bigger issue. Most scientists would agree that life exists elsewhere in the universe, and many would agree life not unlike our own does or has existed. But tourism across interstellar distances is hugely problematic and hugely expensive. Even EM communications beyond a few hundred years light requires enormous energy [and expense]. Why would a successful sentient species make such an enormous investment? Would they not have other resource intensive issues - like food, fuel, housing, education, medical care, amusement, infrastructure, government, and defense to worry about?

 

[emc2cracker]

'Only' 9% of the stars in the milky way are class G? - 9% of ~200 billion is 'rare'? The 'rare earth' argument is rather flimsy. We already know that moderate and lower luminosity stars constitute the majority of all stars, and stars without planets are the exception, not the rule. It is true that planets orbiting a red dwarf stars in the habitable zone would become tidally locked, but, how certain are we this would occur before life could arise and evolve? An intelligent species could develop substantially technological capabilities in a few million years.

Well if there is a galactic habitable zone that would take it down a little lower, but thank you. Since you lay it out that way it doesn't seem quiet as depressing. I am hoping tidal lock doesn't necessarily mean advanced life cannot develope. But we won't know until we get to or study more about the recent discoveries in Libra, the red dwarf with two planets in the habitable zone one most likely a water world on the edge of the zone. That one may not have a tidal lock being on the outskirt of the habitable zone. I recently came across an episode of cosmic journey that talks about these recent discoveries. Check it out these are some of my favorite shows, I sleep with this stuff playing lol.

http://www.hulu.com/watch/119620/cosmic-journeys-the-search-for-earth-like-planets

 

[slide_Rules]

Even EM communications beyond a few hundred years light requires enormous energy [and expense]. Why would a successful sentient species make such an enormous investment? Would they not have other resource intensive issues - like food, fuel, housing, education, medical care, amusement, infrastructure, government, and defense to worry about?

Costs are high, but a scientifically advanced species finds ways to explore. Isn't that the nature of science itself?

If nearby (< 300 ly) intelligent life is extremely rare, a successful sentient species would have a huge scientific interest/curiosity in finding and studying such life.

I'm a fan of a 'Recon Zoo Hypothesis': If we're being observed (or if we are to observe in the far future), it is / will be from very far away - with stealthy super-Hubble type probes and scopes.

 

[emc2cracker]

I don't know about that, I mean on our own planet anytime an advanced civilization comes across a more primitive one... the latter gets the short end of the stick. If indeed a more advanced civilization does find us, I think it will be a very very bad day for humans.

 

[dodo]

This is so cool: http://www.youtube.com/watch?v=65gbieOoD74".

 

[Chronos]

The Milky Way is about 100,000 light years across. Abusing the Drake equation and assuming ~6 intelligent civilizations exist at any given time in our galaxy, the average distance between them is no less than about ~ 16,000 light years. That is an imposing haystack. Even terrawatt transmitters would not be powerful enough to send detectable EM signals over such distances. How long would intelligent alien civilians put up with this kind of drain on their energy sources before voting the bums out of office?

 

[qraal]

I don't know about that, I mean on our own planet anytime an advanced civilization comes across a more primitive one... the latter gets the short end of the stick. If indeed a more advanced civilization does find us, I think it will be a very very bad day for humans.

Maybe to go to the stars they might need to become more advanced ethically too?

Alternatively we're in an unexploited pocket of the Galaxy and we're lucky we weren't 'orbiformed' for some big construction job...

 

[emc2cracker]

Maybe to go to the stars they might need to become more advanced ethically too?

Alternatively we're in an unexploited pocket of the Galaxy and we're lucky we weren't 'orbiformed' for some big construction job...

Or destroyed for an intergalactic highway... lol. But to say that good will and moral advancment must precede technical advancment flies in the face of all we know of ourselves. WAR has spurred technological advancment here, the space race was a mask for building the biggest rocket to carry the biggest bombs. I suspect any other advanced race has probably grown in similar ways... right now with no soviet union we have stalled in our advancment and our exploration of space. This speaks to the fact we should be VERY careful when we find intellingent life because if they are more advanced than us, odds are our meeting will be the beginning of the end of our civilization.

 

[Freeman Dyson]

'Only' 9% of the stars in the milky way are class G? - 9% of ~200 billion is 'rare'? The 'rare earth' argument is rather flimsy. We already know that moderate and lower luminosity stars constitute the majority of all stars, and stars without planets are the exception, not the rule. It is true that planets orbiting a red dwarf stars in the habitable zone would become tidally locked, but, how certain are we this would occur before life could arise and evolve? An intelligent species could develop substantially technological capabilities in a few million years.

The vastness of space is the bigger issue. Most scientists would agree that life exists elsewhere in the universe, and many would agree life not unlike our own does or has existed. But tourism across interstellar distances is hugely problematic and hugely expensive. Even EM communications beyond a few hundred years light requires enormous energy [and expense]. Why would a successful sentient species make such an enormous investment? Would they not have other resource intensive issues - like food, fuel, housing, education, medical care, amusement, infrastructure, government, and defense to worry about?

Well, the US has managed to make a sizable investment in space programs at the expense of other stuff. Ever heard the song, "Whitey on the Moon"? lol

"I can't pay no doctor bills
but whitey is on the moon"

Basically a song about a black guy bitching that his people are in poverty while the government is focused on moonshots.

A species that advanced I imagine would not have to worry much about funding medicaid and food production. They may not even have such needs. We wouldn't know how an enormous of an investment it would be to them.

And it wouldn't be tourism. It would be science. Darwin may have technically been a tourist when he took his long voyages across the globe, but he was also a scientist. No matter how small or insignificant an organism may seem, you will always be able to find somebody who is interested in studying it.

 

[emc2cracker]

Well, the US has managed to make a sizable investment in space programs at the expense of other stuff. Ever heard the song, "Whitey on the Moon"? lol

"I can't pay no doctor bills
but whitey is on the moon"

Basically a song about a black guy bitching that his people are in poverty while the government is focused on moonshots.

A species that advanced I imagine would not have to worry much about funding medicaid and food production. They may not even have such needs. We wouldn't know how an enormous of an investment it would be to them.

And it wouldn't be tourism. It would be science. Darwin may have technically been a tourist when he took his long voyages across the globe, but he was also a scientist. No matter how small or insignificant an organism may seem, you will always be able to find somebody who is interested in studying it.

I agree with everything but the part about exploration being for science. Though that is a very high probability, I would argue what if they are simply expansionist. What if we run across an advanced form of ancient Rome, a civilization that thrives on slavery, a civilization that all its citizens exist in a luxurious world created by the destruction and bondage of other civilizations? Such a civilization would have probably more of a drive for exploration than one based on science, so maybe it would be a good possibility we may run into bad guys first if we run into anyone. I hope that's not the case because we are wide open, maybe if that is the case it would be better if Earth was rare.

I would hope if we run into E.T. he would simply give us the blueprints to his spaceship and their database on medicines and longevity, maybe take me for a trip around the galaxy lol. So I hope you are correct and we run into scientific species if anyone.

 

[Freeman Dyson]

I agree with everything but the part about exploration being for science. Though that is a very high probability, I would argue what if they are simply expansionist. What if we run across an advanced form of ancient Rome, a civilization that thrives on slavery, a civilization that all its citizens exist in a luxurious world created by the destruction and bondage of other civilizations? Such a civilization would have probably more of a drive for exploration than one based on science, so maybe it would be a good possibility we may run into bad guys first if we run into anyone. I hope that's not the case because we are wide open, maybe if that is the case it would be better if Earth was rare.

I would hope if we run into E.T. he would simply give us the blueprints to his spaceship and their database on medicines and longevity, maybe take me for a trip around the galaxy lol. So I hope you are correct and we run into scientific species if anyone.

Well, it has been proposed by some...that any species that makes it to that technological level without destroying themselves have developed some kind of altruistic or peaceful values or else they would have killed themselves long ago.

 

[emc2cracker]

Or they just ran out of people to kill in their galaxy.. after they killed off the rest of their own kind I wonder how they would great a different species??

I mean I'm not dismissing your argument its VERY valid. You point out yourself we have no idea about their resources or what kind of investment space travel would be for them, on the same token we have no idea how they advanced. BUT I think based on our own history we can see that warfare feeds advancement more than peace does.

This whole discussion has gave me the following notion:

Assuming that life may have started springing up at the same time in the universe due the the dispersion of heavy elements, structures of galaxies and such, it is possible we are the first technological advanced lifeforms in our part of the universe. IF there there is a method and structure to life in the universe, and if there are more advanced civilizations than us, then it may be likely they advanced faster because they were more expansionist and non tolerant of other races or species. Now I don't have any basis for my hypothesis besides logic, but when talking about life out there I think its a pretty good notion. I do think that life has some consistency in its frequency and advancement, partly because if it was possible for advanced life to have formed billions of years ago then we would probably see lots of evidence of them, even here in our own galaxy or maybe as far as andromeda.

But also based on our own history, if that hypothesis has any teeth it may be very likely we are the first in our corner of the universe at least. And lucky for us, maybe not lucky for whoever we discover ages from now but who knows. It seems mankind has taken a turn towards enlightenment and a step away from self destruction, so though advancement may be slower from here on out we have had a jump start maybe on other civilizations.

But I do think if life is common, that lots of civilizations indeed will destroy themselves. However I think its also likely that some may simply kill off their enemies and then start looking for more. Let's look back and imagine Hitler developing the atom bomb and nobody else, or imagine Hitler winning world war II with no atom bomb. One might imagine the third reich being left here in peace and looking for more unclean species or races to exterminate, if indeed they didn't poison their own planet beyond their ability to live on it. Probably a bad example but the best I can think of in our own history, besides maybe an ever expanding Roman Empire that didn't fizzle.

Does that sound logical at all?? lol I hope it does I put a lot of thought into this notion. Thank you Freeman your input helped me dream that up lol. Karl Sagan's Cosmos was the first time I heard the notion you mention, I remember thinking if life was as rampant as he hoped it may be that there are exceptions to that very idea, though it probably has more teeth than my idea lol.