Intelegent life in the Universe, how common is it?

[Urban Ranger]

Originally posted by Odin
I said COMPLEX LIFE needed photosynthesis. Read the post before you spew stuff I already know. Chemoautothrophy is enough to sustain microbes, but animals need oxygen, and oxygen comes from photosynthesis, which cannot occur on Europa.

I am not sure that animals need oxygen. Oxygen is an oxidising agent that drives processes to release energy in the animals and plants on earth. Fundamentally though the important thing is energy.

[smacksim]

Considering all the new evidence for planets coming in, just this week even, my questions are:

When do you think we'll find a terran-like planet?
20 years, 40, 60, ? It will certainly be 15, until the new scopes are in orbit.

When will we find other life in the universe?
IE, how likely do you think it is that we'll find it on one of Sol's other rocks, or will we detect a methane-oxygen atmosphere (life for sure) on an extra-solar first? Or will it have to wait until we actually go somewhere else, which could be quite long.

And agree with Urban Ranger that animals, in the sense of multi-celled specialized-celled macroscopic critters with motility, don't necessisarily need Oxygen. But AFAIK the terran Kingdom Animalia depends utterly on Oxygen. Just think about photosynthesis. For a long time everyone believed there was only one photosynthetic pathway and energy cycle. Then CAM and C4 photosynthesis were discovered in Cacti. It is not at all inconceivable to imagine cellular respiration with other chemical models.

-S

[Darkstar]

Originally posted by Odin


I said COMPLEX LIFE needed photosynthesis. Read the post before you spew stuff I already know. Chemoautothrophy is enough to sustain microbes, but animals need oxygen, and oxygen comes from photosynthesis, which cannot occur on Europa.

Life is most likely to start in water because water can desolve more things than any other natural substance and because it expands as it freezes. I'm not ruling it out, I'm just saying it's unlikely

And you are COMPLETELY WRONG. We have COMPLEX LIFE at the bottom of the oceans that live PURELY inside eco-systems that never, ever, ever touch photosynthesis. You just need an energy source. You should go check out the smokers... and theres also the deep water super brine ecosystems. Both feature microbial life that fill that "photosysnethsis" energy harvestors that plants do on the surface. No photosynthesis involved. Those food chains goes up to highly advanced animals including crabs and octipi relatives. They are being studied very intensely by NASA... whole eco-systems that have ZERO input from sunlight, and have ZERO input from photosynthesis.

Water was convenient for us. That's why we need it. But again, that is merely one instance. We should not presume. Life, if it exists elsewhere, will use whatever is handy. That's the way of life. Now, if we want to go sit down and have tea with Intelligent life, it would be nice if they are mostly water, like us. Otherwise, it could be inconvienent trying to be around each other.

[Odin]

Originally posted by Urban Ranger


I am not sure that animals need oxygen. Oxygen is an oxidising agent that drives processes to release energy in the animals and plants on earth. Fundamentally though the important thing is energy.

Some archaebacteria use sulfur insread of oxygen for aerobic respiration, but for the most part, organics burned in oxygen is one of the best sources of energy available to life, since oxygen is one of the most common elements in the universe. Also, Fermentation is too inefficient for large organisms. The rules of chemistry are the same throughout the universe, the molecules in one planets primordial soup should be similar to the next. the exact amino acids and the structure of nucleic acids would differ from world to world, but the biochemistry should be broadly similar.

[Darkstar]

Originally posted by Urban Ranger
We have a crystal ball, don't we?

Individually, maybe. In every aspect, highly unlikely.

About Titan? Have you ever *looked* at the data? How do you expect something at the average temperature of liquid methane to use *liquid water*? The fact that water (H20) is also very rare there... it's mostly hydrocarbons, not Hydooxides.

In every aspect, yes. But water is convinent. There's better heat conductors then copper, but we use copper a lot in electronics for heat conductors. Why? It's convinent.

[Darkstar]

Originally posted by Odin
Some archaebacteria use sulfur insread of oxygen for aerobic respiration, but for the most part, organics burned in oxygen is one of the best sources of energy available to life, since oxygen is one of the most common elements in the universe. Also, Fermentation is too inefficient for large organisms. The rules of chemistry are the same throughout the universe, the molecules in one planets primordial soup should be similar to the next. the exact amino acids and the structure of nucleic acids would differ from world to world, but the biochemistry should be broadly similar.

But the conditions for life won't be. And that's what the "Only Earth twins" parameters overlook.

[Odin]

Originally posted by Darkstar


And you are COMPLETELY WRONG. We have COMPLEX LIFE at the bottom of the oceans that live PURELY inside eco-systems that never, ever, ever touch photosynthesis. You just need an energy source. You should go check out the smokers... and theres also the deep water super brine ecosystems. Both feature microbial life that fill that "photosysnethsis" energy harvestors that plants do on the surface. No photosynthesis involved. Those food chains goes up to highly advanced animals including crabs and octipi relatives. They are being studied very intensely by NASA... whole eco-systems that have ZERO input from sunlight, and have ZERO input from photosynthesis.

those animals could nor have evoled in the first place if PHOTOSYNTHESIZERS hadn't made oxygen. Remember, ALL animals need oxygen, many microbes don't. There is a huge difference between bacteria and tube worms. There can be no photosynthesizers on Europa, hence NO OXYGEN FOR ANIMALS.

[Darkstar]

Wrongo, Odin. There's sources for oxygen in the deep ocean that are completely unrelated. Remember, science currently believes they came first, before plants and photosynthesis. If that's so, that means there were no plants on the surface making O2 (that do not reach the deep waters in the first place, but you don't seem to be interested in that aspect). So they started utilizing oxygen before plants existed.

Honestly, I think it would do your interests a world of good to check out the latest on deep ocean eco-systems, the actors in the systems, etc etc etc.

And again, you presume.

All you need is electricity through H2O to get Oxy. And you can get that in an amazing number of ways. So, even if you say "You gotta have free oxygen!", then there is indeed the possibility to have free oxy roving around on Europa.

Heck, Europa isn't even the only water ocean moon in the solar system that we know of. So I don't know why you are so stuck on that one world.

And finally... when we begin talking about *life*, then you cannot accurately say

all animals need oxygen

That's cause we don't know that as a fact. We know that all terran animals need oxygen (not 100% true, but it is close enough for our discussion here).

We can presume many things by looking at what's in this one, isolated lab of life that we know of. Using it as a model, we can guess and hypothesize. But until we find other worlds full of life and can study them, we can not say that the only possiblity for complex life requires liquid water and oxygen. We can say, we know that complex life on earth require water and oxygen, and therefore life might repeat itself in some way under similar conditions. And that's what we really want. To find something very similar to ourselves out there that will be able to talk to us. And will bother to talk to us.

[Odin]

Originally posted by Darkstar
All you need is electricity through H2O to get Oxy. And you can get that in an amazing number of ways. So, even if you say "You gotta have free oxygen!", then there is indeed the possibility to have free oxy roving around on Europa.

Not enough to sustain areobic respirayion in large organisms, though. I don't think its a coincidence that the first animals appeared 700 million years ago when the oxygen level passed 15% for the first time (animals didn't diversify until just before the Cambrian because of a series of global ice ages, "Snowball Earth" events, between 800 and 600 million years ago).

[Boris Godunov]

Originally posted by Darkstar
See, that's just the wrong answer. We are delicate about those matters, but anything that actually evolved there wouldn't be.

Now, if we just want to find mammalian life, then we know *precisely* what to look for... earth like worlds with one or more large satellites that receive a certain amount of radiation, and has undergone several large killing incidences so as to create an environ to allow mammals to become the dominate life form.

Of course, the desire to find "mammalian" life is probably more out of some teenage Star Trek fantasy then genuine interest in finding real intelligent life, but heh, I suppose that's the only hope until "holo-decks" are invented and installed in some people's houses.

I then suggest you take up some issues with your colleagues at NASA:

http://nai.arc.nasa.gov/news_stories/news_print.cfm?ID=157

"Staying away from the galactic center has an additional advantage. The center of the Galaxy is awash in harmful radiation. Solar systems near the center would experience increased exposure to gamma rays, X-rays, and cosmic rays, which would destroy any life trying to evolve on a planet. "

There are other reasons why being closer to the center would be bad:

"Being in the outer region of the Galaxy protects our Solar System from the huge gravitational tug of stars clustered near the galactic center. If we were closer in, the combined gravity of all those stars would perturb the orbit of comets in the Oort cloud. The Oort cloud, which circles the outer perimeter of our Solar System, contains trillions of comets. The gravitational disturbances caused by other stars would send many of those comets in our direction - increasing the rate of comet impacts and endangering - if not eventually wiping out - life on Earth."

Overall, the article focuses on "Galactic Habitable Zones," which are indeed rare.

[DanS]

And that's what we really want. To find something very similar to ourselves out there that will be able to talk to us. And will bother to talk to us.

I agree that this is what we want, but economy suggests that this is a waste of time and money, considering that we would probably find them incidently while doing higher priority research, if they exist. For instance, we might find them while looking for worlds like ours. The highest imperative is to understand the broadest range of life on such worlds.

Sometimes I become frustrated when I hear about money going to SETI. Drake's equation seems like it is used to justify the work. Of course, people (like me) waste enormous sums of money on new plasma TVs too, so as long as it's not the government spending the money...

[child of Thor]

I think the universe is teeming with 'intelligent' life - thats why they haven't contacted us yet as we are too stupid to probably keep ourselves or our planet alive.

[Flinx]

Originally posted by Edan

Originally posted by Dr Strangelove
So far most of the planets discovered outside of our solar system have been huge, around Saturn sized, and having orbits as close in to their respective suns as Venus or Mercury. Based on that information alone I don't think that life is likely to be very common.

Maybe that's because it's easier to spot huge Saturn sized planets?

The technique used to date, looks for the wobble caused in a star by the gravitational pull of its planets. This means:
-The larger the planet relative to the star, the bigger the wobble
-The closer the planet is to the star, the bigger the wobble
-The closer the planet is to the star, the faster the wobble

It would take up to 30 years of observational data to detect Saturn using this technique.

So far we only have enough data to find large gas giants in Mercury to Asteroid Belt locations.

Given the theories of stellar formation, stars with gas giants this close in are unlikely to have terrestrial planets in the same region.

[lord of the mark]

Originally posted by Darkstar
We are just so self-centered and self-absorded that we simply refuse to believe that anything but "odd colored humans with some schmuck on their face"

Yiddish/Yinglish lesson of the day:


Surely you mean with some schmutz on their face, not with some schmuck on their face. Schmutz means dirt 0 schmuck is used to refer to a fool, but literally means a penis (you can think of English parallels, Im sure)

Id rather not think about an alien with some schmuck in his face.

[DanS]

One of the problems with Drake's Equation is that you get stupid arguments like the following one, which banks on concensus "science" to assert a fact that can neither be argued against nor verified. When did science start running on such stuff?

First Contact Within 20 Years: Shostak

Will the 20s see ET roar onto center stage
Mountain View CA (SPX) Jul 22, 2004
If Intelligent life exists elsewhere in our galaxy, advances in computer processing power and radio telescope technology will ensure we detect their transmissions within two decades. That's the bold prediction from a leading light at the Search for Extraterrestrial Intelligence Institute in Mountain View, California.

Seth Shostak, the SETI Institute's senior astronomer, based his prediction on accepted assumptions about the likelihood of alien civilisations existing, combined with projected increases in computing power.

Shostak, whose calculations will be published in a forthcoming edition of the space science journal Acta Astronautica, first estimated the number of alien civilisations in our galaxy that might currently be broadcasting radio signals.

For this he used a formula created in 1961 by astronomer Frank Drake which factors in aspects such the number of stars with planets, how many of those planets might be expected to have life, and so on. Shostak came up with an estimate of between 10,000 and 1 million radio transmitters in the galaxy.

To find them will involve observing and inspecting radio emissions from most of the galaxy's 100 billion stars. The time necessary for this formidable task can be estimated from the capabilities of planned radio telescopes- such as SETI's 1-hectare Allen Telescope Array and the internationally run Square Kilometre Array- and expected increases in the power of the microchips that sift through radio signals from space.

Shostak assumed that computer processing power will continue to double every 18 months until 2015- as it has done for the past 40 years. From then on, he assumes a more conservative doubling time of 36 months as transistors get too small to scale down as easily as they have till now.

Within a generation, radio emissions from enough stars will be observed and analysed to find the first alien civilisation, Shostak estimates. But because they will probably be between 200 and 1000 light years away, sending a radio message back will take centuries.

Paul Shuch, executive director of the SETI League, a separate organisation in New Jersey, says Shostak's prediction ignores one important factor. "It is altogether reasonable to project the development of human technology, based upon past trends and planned investments," he says.

"But predicting the date, the decade or even the century of contact is another matter because the 'other end' of the communications link is completely out of our hands. It would be nice to think we know something about the existence, distribution, technology and motivation of our potential communications partners in space, but in fact, we don't."

Shostak admits that there are myriad uncertainties surrounding his prediction, but he defends the basis on which he made it. "I have made this prediction using the assumptions adopted by the SETI research community itself."

http://www.spacedaily.com/news/seti-04e.html