How plausible is the idea that life originated only on Earth?

So far, there's no evidence that life originated anywhere other than on Earth. But, it's early days yet.

Given the statistics of the number of galaxies and stars within each... and given enlarging statistics on the fact that there are planets around other stars... i think its merely a question of probability. Yes, there is probably life elsewhere in the universe... even if its not as evolved as us... but it could probably be more evolved too. Who knows.

How plausible is the idea that life originated only on Earth?

The known universe is big damned place, with lots and lots of stars/suns, and probably with lots of planets. The odds are overwhelming that life is occuring on some of them.

I, for one, consider that if no other planet has life as we know it, then it can only be due to god, not nature.

Baron Max

but it could probably be more evolved too. Who knows.

What does one mean when they say "more evolved"?

What does one mean when they say "more evolved"?

People usually use that as a measure compared to how far along humans evolved. "More evolved" would mean ...further along the evolutionary scale as measured by human evolution. I.e., better than humans are at present.

Baron Max

"More evolved" would mean ...further along the evolutionary scale as measured by human evolution.

I don't think evolution would have to follow the same path it has taken here on earth even given the same initial conditions and timespan. In fact I see no reason why it would even be close to the path life has taken here. There does not have to be reptiles evolving into birds and mammals etc. I don't believe in an "evolutionary scale" as you put it.

I.e., better than humans are at present.

Are we the best then? Are we the pinnacle of evolution on our planet?

Are we the best then? Are we the pinnacle of evolution on our planet?

I would think so. We have reached a point where our intellectual abilities are allowing us to adapt the environment instead of adapting to it.

Now is this is actually a good thing? Perhaps not. Perhaps a more "evolved" form of life would know how to do this without damaging his own environment like we've been doing.

How plausible is the idea that life originated only on Earth?

not Plausible at all...comets*.

Considering the size of the universe, it's highly improbable that life exists only on Earth. You have to accept that bacteria also coutns as life.

We don't know much even about our own galaxy; but that doesn't mean there's no life anywhere else out there.

I saw an article once (wish I'd saved it) saying that lifeforms have been discovered in some strange places, like crevices deep in the earth. They seem to not be related to anything in our animal/plant paradigm. It didn't go into enough detail about whether it's based on DNA, but it raised the question about whether life had actually originated more than once, and the last wave was so successful that it out-competed the survivors of the earlier waves.

If it's true that life originated on earth more than once, then it's pretty likely that it happened somewhere else too. I just haven't been able to find anything on this in a long time.

No, it wasn't a tabloid. A respectable newspaper like the L.A. Times or Washington Post.

I saw an article once (wish I'd saved it) saying that lifeforms have been discovered in some strange places, like crevices deep in the earth. They seem to not be related to anything in our animal/plant paradigm. It didn't go into enough detail about whether it's based on DNA, All life on Earth is based on DNA, including these microbes found deep in the Earth. but it raised the question about whether life had actually originated more than once, and the last wave was so successful that it out-competed the survivors of the earlier waves.
This is an interesting concept known as the Shadow Biosphere.
http://en.wikipedia.org/wiki/Shadow_biosphere
http://www.scienceagogo.com/news/shadow_biosphere.shtml
One possible shadow biosphere is a population of microorganisms which might at one time been transported from Mars to Earth, or even from Earth to Mars and back again, inside meteorites. But this is speculation, as no such shadow biosphere has been found.


If it's true that life originated on earth more than once, then it's pretty likely that it happened somewhere else too. I just haven't been able to find anything on this in a long time. Keep looking; there is plenty of good stuff on this subject; but as I said, all informed speculation.

All life on Earth is based on DNA, including these microbes found deep in the Earth

History has produced RNA lifeforms

Yes; but none are alive at the moment. The only exceptions to the DNA rule I know of are prion-based diseases such as Creutzfeldt-Jakob disease (http://en.wikipedia.org/wiki/Creutzfeldt-Jakob_disease), and non-biological artificial lifeforms such as robots and other a-life (http://en.wikipedia.org/wiki/Artificial_life) varieties such as simulations on computer.

there are 7 subdivisions in virusses only 3 of them use DNA the others use RNA
http://en.wikipedia.org/wiki/DsRNA_virus

Most life however uses DNA even the sulpher breathing/eating ones

I gotta agree with Tristan. Especially if the universe is flat---then there are not only other life forms in the universe, but exact copies of us (probably not in our Hubble volume, though).

yeah if your looking at a multiverse level where there are still planets where elvis lives then their are infinite earths alone and who know how many other places

yeah if your looking at a multiverse level where there are still planets where elvis lives then their are infinite earths alone and who know how many other places

Not necesarily a multiverse---if the universe is flat, then it is infinite. The part of the universe we see is finite, but universe as a whole (if this is even a meaningful statement) is infinte. That means there are infinite copies of Earth, all with their own unique histories. (This is analagous to finding, say, War and Peace encoded in pi. Funny things happen at infinity---nothing is improbable anymore, and everything happens infinitely many times.)

The more interesting question is if there are any intelligent life forms in our galaxy. Does anyone know Fermi's paradox? Can anyone explain it to me?

there are 7 subdivisions in virusses only 3 of them use DNA the others use RNA
http://en.wikipedia.org/wiki/DsRNA_virus

Most life however uses DNA even the sulpher breathing/eating ones
Interesting; thanks.
Of couse many people, even virologists don't think of virii, or prions, as living organisms, as they can't replicate independently. But there were supposedly independently living RNA organsisms billions of years ago, according to the RNA World hypothesis
http://en.wikipedia.org/wiki/RNA_world_hypothesis

Space is soo big and and we didnt explored a 0.000000000000000000000000001 part of it so in that fact i would say there is 99% to find a one living life form somwhere it could be a microbe or virus maybe alien but it has to be :rolleyes:

btw (0.000000000000000000000000001 ) <---this number is from my head just.but its something near truth maybe few 0 are still missing.

Space is soo big and and we didnt explored a 0.000000000000000000000000001 part of it so in that fact i would say there is 99% to find a one living life form somwhere it could be a microbe or virus maybe alien but it has to be :rolleyes:

btw (0.000000000000000000000000001 ) <---this number is from my head just.but its something near truth maybe few 0 are still missing.

actually afther the vikings on Mars and the moon camera embarrassment it's save to say that only earth is properly diagnosed.
Then again like they usely say in science, is that it's inpossible to disprove life it's only possible to proof life.

It is now estimated that there are: 70000000000000000000000 stars (note that this 4% of the universe known "stuf" and that it can even be infinite little if you believe in a multivers)

so the changes of finding something are pretty large altough like eburacum45 says their always going to be scientist who are going to dispute life.

note that Mistletoe also can't survive without a host because it can't absorb water and note that even human have to eat and are therefore depended from a outside food source and I'm not going to start on their assexual replicating abilities

The greatest weight.— What, if some day or night a demon were to steal after you in your loneliest loneliness and say to you: "This life as you now live it and have lived it, you will have to live once more and innumerable times more; and there will be nothing new in it, but every pain and every joy and every thought and sigh and everything unutterably small or great in your life will have to return to you, all in the same succession and sequence—even this spider and this moonlight between the trees, and even this moment and I myself. The eternal hourglass of existence is turned upside down again and again—and you with it, speck of dust!"— Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experienced a tremendous moment when you would have answered him: "You are a god and never have I heard anything more divine!" If this thought gained possession of you, it would change you as you are or perhaps crush you; the question in each and every thing, "Do you desire this once more, and innumerable times more?" would lie upon your actions as the greatest weight! Or how well disposed would you have to become to yourself and to life to crave nothing more fervently than this ultimate eternal confirmation and seal?

The Gay Science
Nietzsche

Erm...reincarnation thread?

Erm...reincarnation thread?

Erm...reincarnation thread?

ad infinitum in extremis

The greatest weight.— What, if some day or night a demon were to steal after you in your loneliest loneliness and say to you: "This life as you now live it and have lived it, you will have to live once more and innumerable times more; and there will be nothing new in it, but every pain and every joy and every thought and sigh and everything unutterably small or great in your life will have to return to you, all in the same succession and sequence—even this spider and this moonlight between the trees, and even this moment and I myself. The eternal hourglass of existence is turned upside down again and again—and you with it, speck of dust!"— Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experienced a tremendous moment when you would have answered him: "You are a god and never have I heard anything more divine!" If this thought gained possession of you, it would change you as you are or perhaps crush you; the question in each and every thing, "Do you desire this once more, and innumerable times more?" would lie upon your actions as the greatest weight! Or how well disposed would you have to become to yourself and to life to crave nothing more fervently than this ultimate eternal confirmation and seal?

The Gay Science
Nietzsche


Stupid :bugeye: but sometimes i feel like this how you described knowing it has no sence :D

note that this 4% of the universe known "stuf" and that it can even be infinite little if you believe in a multivers

You don't have to believe in the multiverse to say that the universe is infinite---just that it is flat (that is, Omega = 1). This seems to be what the experimenters are telling us.

The more interesting question is if there are any intelligent life forms in our galaxy. Does anyone know Fermi's paradox? Can anyone explain it to me?

Fermi's paradox is a little like the time travel paradox. There is a very high probablilty that there are many advanced civilisations out there (especially in a very old and flat universe). A lot of these civilisations wil be mre advanced than us. They should be able to travel very fast. They should have been sending radio signals for a long time now.

So why then do we have no evidence for it?

Its just like why do we not find evidence for travellers from the future?

I did not answer the poll because it did not give enough choices.

From the history of the Earth and other considerations, I would bet that life exists elsewere in the universe and very likely elsewhere in our galaxy, but not in our solar system.

Also from the history of the Earth and other considerations, I expect intelligent life to be extremely rare. It would not surprise me to discover that we are the only intignet species in our galaxy.

Note that life appeared on Earth at almost the earliest time it was possible for it to exist, suggesting that given suitable conditions life will come occur.

Note also that intelligent life did not show up until very recently. If you represent the history of the Earth by 1000 days, intelligent life appeared less than a minute ago. Note that the dinosaurs were an evolutionary success for over 100 million years, without progressing toward intelligence.

The above suggests that intelligence might be a lucky fluke rather than an evolutionary inevitability.

BTW: Most are aware that there is a habitable zone in a solar system. Too far away, too cold; Too close, too hot. Not many are aware that there is a habitable zone in a galaxy. Too close to the center, too much radiation & too much gravitationaly interaction; Too far away from the center,l not enough ehavey elements like oxygen, carbon, iron, et cetera.

Consideration of habitable zones cuts down the odds on suitaboe conditions by many orders of magnitude.

How plausible is the idea that life originated only on Earth?

Any kind of life? I would say it is impossible that life only formed here. I would be shocked if there isn't life somewhere else in our solar system, either now or in the past.

The building-blocks of life are in meteors and interstellar dust. Carbon-based compounds now seem very common, rather than rare. And the more extremophiles we find, the more we have to broaden the scope of *where* life can exist.

Do you really want to know about sentient, technological life? Because that is just as amazing a step as life itself, making it all the more unlikely to be widespread.

200 billion solar systems in a galaxy, 300 billion galaxies in the known universe, take into account the possibility of a multiverse, I think the chances of us been alone are pretty slim.

Have any of you considered the Exogenisus hypothesis?

Have any of you considered the Exogenisus hypothesis?

Are you meaning panspermia, or yust that we little monkeys have been tampered with.

Personally I believe that there should be millions of planets in this galaxy alone that have life, but only a handful that have the ability to be(come) habitable to multicellular lifeforms.

there certainly is some freaky art out there that make denouncing aliens without any proof yust as stupid as saying that they are here truly exist
http://upload.wikimedia.org/wikipedia/en/2/2d/Ancientastronauts.jpg

Are you meaning panspermia, or yust that we little monkeys have been tampered with.

Personally I believe that there should be millions of planets in this galaxy alone that have life, but only a handful that have the ability to be(come) habitable to multicellular lifeforms.

there certainly is some freaky art out there that make denouncing aliens without any proof yust as stupid as saying that they are here truly exist
http://upload.wikimedia.org/wikipedia/en/2/2d/Ancientastronauts.jpg

Yes. Those are clearly aliens. :rolleyes:

Yes. Those are clearly aliens

I never said that, I yust thought it's a funny picture I was looking if there ever was a cavepainting from a neanderthal, they maded pictures from humans and animals so I tought it was weird why they never made a picture of them.

Loose from actually believing in aliens I would never believe that some of them visit through history and leave some cryptic clues around.

I never said that, I yust thought it's a funny picture I was looking if there ever was a cavepainting from a neanderthal, they maded pictures from humans and animals so I tought it was weird why they never made a picture of them.

Loose from actually believing in aliens I would never believe that some of them visit through history and leave some cryptic clues around.

If they are here, they are obviously interested in our cattle and wheat, and not us.

they are here, they are obviously interested in our cattle and wheat, and not us.

Ah yes the intilligent life forms, I'm still not agreeing with the interstellar voting on this one.
The only thing sure it that if they exist that they either don't care or can't visit us and that we can't do nothing from our side beside hope that the next telescope can image them or something.

>> there's no evidence that life originated anywhere other than on Earth.>>>>

oh yes there is... many LIFE forms can travel through space, unharmed.

Now according to BS Darwinianism, where did they get that idea from ???

Open your mind, the truth is really all in, but many people wish to believe in fantasies.

there's life on all planets. even in the sun.
but not the same kind of life as on earth.

Let's say we recieved a long awaited radio signal indicating there is an intelligent life form living (or was) on another planet around some distant star system on the other side of the galaxy approx. 60,000 or 70,000 light years away. Then what?

Then it's time to get decoding that signal!!!!!!

If there was a civilization exactly like ours orbiting another star, how close would it have to be for us to pick up it's radio/TV signals assuming they did everything the same way we do?

I saw an article once (wish I'd saved it) saying that lifeforms have been discovered in some strange places, like crevices deep in the earth. They seem to not be related to anything in our animal/plant paradigm. It didn't go into enough detail about whether it's based on DNA, but it raised the question about whether life had actually originated more than once, and the last wave was so successful that it out-competed the survivors of the earlier waves.

If it's true that life originated on earth more than once, then it's pretty likely that it happened somewhere else too. I just haven't been able to find anything on this in a long time.

No, it wasn't a tabloid. A respectable newspaper like the L.A. Times or Washington Post.

This sort of relates to the tangent I went off on in the thread about high IQ societies.

Back in the late 70s, there was this guy named Carl Woese, who was sequencing ribosomal RNA in bacteria that some colleagues had collected. He was trying to figure out where these bacteria were on the evolutionary tree of life, phylogenetically, that is, by looking at the similarities in highly conserved regions on the genome.

He soon found that some of these bacteria were radically different (molecuarly) from either the prokaryotes or eukaryotes. So different, in fact, that they warranted an entire new branch on the tree of life. These became known as the Archaea (after over a decade of grueling scientific dispute). This difference between the three kingdoms cannot be stressed enough– it's a bigger difference between a bacteria cell and a Archaea than that of a lobster and an elephant.

These Archaea are found to live in some of the most extreme environments on earth. They have been found in black smokers– volcanic vents thousands of feet down, on the sea floor, living in water near 100°C and a pressure of 380 atmospheres. They've been found in polar ice, in the places where the salt concentration is 10x that of the sea, in environments with pHs above 9 and below 3.

Some they've found almost 3 kilometers under the earth's crust, which reduce iron using hydrogen for energy, excreting magnetite as a waste product. While we eat sugar and burn it with oxygen for energy, these things eat metal.

It's not a question of whether or not life is out there, but one of us being able to recognize it.

If there was a civilization exactly like ours orbiting another star, how close would it have to be for us to pick up it's radio/TV signals assuming they did everything the same way we do?

Well it would take roughly between 4 and 50,000 years for the radio waves to reach us from any star sytem in our galaxy. Thats 200 billion stars. There is no reason not to believe that advanced civilisations could have been developed on another planet within our galaxy in that time-frame.

Well it would take roughly between 4 and 50,000 years for the radio waves to reach us from any star sytem in our galaxy. Thats 200 billion stars. There is no reason not to believe that advanced civilisations could have been developed on another planet within our galaxy in that time-frame.
Yes, but how faint would the signals be? Could they be picked up?

I am not so sure life originated only on earth. It's a very open-ended question, but I do tend to be reminded of Harold and Urey despite their putative flaws.

Yes, but how faint would the signals be? Could they be picked up?

http://www.space.com/searchforlife/seti_shostak_tv_061109.html

Hey everyone.

I'm just new to this site, and this is my first post, so please try not to be too harsh.

With the universe being flat:
How is that possible, as we are all clearly able to move in three-dimensions?

With life beginning only on earth:
I find this to be near impossible to believe due to the fact that there are so many stars, so many celestial bodies orbiting those stars, so many different atoms and and lighting strikes and enzymes capable of producing life, and the final factor is time, which as we know it (or as I know it), is infinite. And anything multiplied by infinity is infinity, so no matter how small the chance of life being created, be it on earth or otherwise, it will always happen.

http://upload.wikimedia.org/wikipedia/commons/9/98/End_of_universe.jpg

the flat universe is obviously the lowest one, you can check http://en.wikipedia.org/wiki/Flat_universe#Flat_Universe if you wan't to know more.

Especially if the universe is flat---then there are not only other life forms in the universe, but exact copies of us (probably not in our Hubble volume, though).I'm intrigued as to the notion that an infinite flat universe = infinite copies of everything?
Why?
I'm not too up to speed on the flat-universe concept but infinity does not equal infinite copies of everything, as far as I know. Or does it??

Well, an average of about 100,000,000,000 stars per galaxy, and approx. 100,000,000,000 galaxies by one estimate. So there's 10^22 stars, and say there's even one planet in each system which is the right distance from its parent star (whatever the size or luminosity of the star, which would make that safe distance extremely variable) and you have 10^22 planets that have the potential (given enough time, say 10^9 years) to develop some form of life. Now intelligent life, you're looking at 3x10^9 years at least. Sentient life, like us, who regard ourselves as intelligent, well we only developed in the last 5 million years. So you're probably looking at 4.5x10^9 years for us. Even so, the first stars appeared in the Universe about 12x10^9 years ago, so I'd say that sentient life (ie somewhere around our level of intelligence) has developed by now, somewhere in the Universe, probably a very long time ago (ca. 7-8x10^9 years ago). I would suggest that the very earliest forms of sentient life has by now reached the stage of surpassing the need for bodies, and has become purely non-physical.

http://www.space.com/searchforlife/seti_shostak_tv_061109.html

So according to this, we couldn't even pick up TV transmissions from Alpha Centauri! What the fuck is SETI doing, then?

Xylene: You numbers are very impressive, although your estimates of stars in a galaxy and number of galaxies might be a bit high.

You are overlooking a few pertinent facts.In a solar system there is a habitable zone. Too close to the star and there is too much heat & radiation. Too far away and it is too cold.


There is also a habitable zone in a galaxy. Too close to the center, too much radiation and too many fast moving stellar objects, likely to disrupt a solar system. Too far from the center and not enough heavy elements like carbon, oxygen, et cetera, very necessary for the biochemistry of life.


The history of our planet suggests that life will occur almost as soon as the conditions are sutable. However, our history strongly suggests that it takes 4 billion years or so for intelligent life to happen.


The history of our planet suggests that intelligent life might be a lucky fluke. The dinosaurs were successful for 100 million years without developing intelligence. They apparently died off due to Earth being hit by an asteroid.


Life is not possible in the first 3-5 (maybe more) generations of stars. The early universe had nothing but hydrogen, helium, and some trace amounts of 2-3 other very light elements. The heavy elements were cooked in the interior of stars, which created gas clouds at the end of their life cycle. It takes maybe a billion years for gas clouds to collapse gravitationally and form a new solar system from gas clouds contaiing those heavy elements.The above are the major issues. There are other considerattions cutting the odds down.

The above indicates that intelligent life is not likely to occur in the first 7-9 billion years of the life of the universe: A few billion years for the first solar system with enough heavy elements and 4 billion years for intelligent life to evolve.

While I expect life to exist on many planets in our galaxy, it is possible that we are the only intelligent life in our galaxy. Some galaxies might not have any intelligent life.

So according to this, we couldn't even pick up TV transmissions from Alpha Centauri! What the fuck is SETI doing, then?

Well, we gotta hope that they're using far greater signalling strength than that which TV stations are designed for!

ever heard of the wow signal (http://en.wikipedia.org/wiki/Wow_signal)

Fact is their is life on earth, Europa isn't lopoking that bad either and Mars has relative large quantities of (organic?) methane. I would say go SETI go

Well, we gotta hope that they're using far greater signalling strength than that which TV stations are designed for!
But why would they be? On earth, the trend is likely to be a weaker and weaker signals as more and more people switch over to cable or satelite TV. It may well be that high powered over the air broadcasting is a short lived phenomena among technological species. Of course, even if it's common, we wouldn't know about it.

It seems to me that if SETI was serious, they would try to build something that could pick up normal transmissions from other solar systems. Unless this is just impossible.

Xylene: You numbers are very impressive, although your estimates of stars in a galaxy and number of galaxies might be a bit high.

You are overlooking a few pertinent facts.In a solar system there is a habitable zone. Too close to the star and there is too much heat & radiation. Too far away and it is too cold.


There is also a habitable zone in a galaxy. Too close to the center, too much radiation and too many fast moving stellar objects, likely to disrupt a solar system. Too far from the center and not enough heavy elements like carbon, oxygen, et cetera, very necessary for the biochemistry of life.


The history of our planet suggests that life will occur almost as soon as the conditions are sutable. However, our history strongly suggests that it takes 4 billion years or so for intelligent life to happen.


The history of our planet suggests that intelligent life might be a lucky fluke. The dinosaurs were successful for 100 million years without developing intelligence. They apparently died off due to Earth being hit by an asteroid.


Life is not possible in the first 3-5 (maybe more) generations of stars. The early universe had nothing but hydrogen, helium, and some trace amounts of 2-3 other very light elements. The heavy elements were cooked in the interior of stars, which created gas clouds at the end of their life cycle. It takes maybe a billion years for gas clouds to collapse gravitationally and form a new solar system from gas clouds contaiing those heavy elements.The above are the major issues. There are other considerattions cutting the odds down.

The above indicates that intelligent life is not likely to occur in the first 7-9 billion years of the life of the universe: A few billion years for the first solar system with enough heavy elements and 4 billion years for intelligent life to evolve.

While I expect life to exist on many planets in our galaxy, it is possible that we are the only intelligent life in our galaxy. Some galaxies might not have any intelligent life.

I 100% agree with all of this and would like to add:

Many systems are binaries, which would make a habitable zone difficult to maintain.

It may be that technological life requires a large moon, to get it out of the water in the first place. Our moon is a very odd feature. Any odd feature may be a necessity that is too obvious for us to fully comprehend.

It may be that technological life needs a planet-busting catastrophe to wipe out any species that get rooted too well to displace.

But, technological life might also need a very large planet, like Jupiter, to keep too many of these impactors from ruining the party.

I think life is very quick to get going, and it is probably elsewhere in our solar system (past or present), but technological life might be astronomically rare (pardon the pun). Trillions and trillions of stars might not be enough to have two of these races in existence at the same time.

And anything multiplied by infinity is infinity, so no matter how small the chance of life being created, be it on earth or otherwise, it will always happen.

or will never happen.

But why would they be?

Because they could be trying to contact us. Think man, think :rolleyes: :D

Because they could be trying to contact us. Think man, think :rolleyes: :D
Sure, that's possible. But what makes more sense, searching for the occasional message intentionally sent to us by aliens that will never live to hear the reply, or searching for the constant signals unintentionally sent to us.

Again, consider aliens trying to detect us from a distant starsystem. Are we sending out high energy signals to intentionally contact aliens? If we're not, why assume they are?

Are we sending out high energy signals to intentionally contact aliens?

Have sent? Yes.

A better question would be how plausible is the idea that DNA-based life originated only on Earth.

Have sent? Yes.
So we have sent such a signal. How long did it last? If an alien race wasn't listening at just the right time, they'd miss it. On the other hand, if they had equipment that could pick up normal TV/radio signals, they could detect us any time.

Again, consider aliens trying to detect us from a distant starsystem. Are we sending out high energy signals to intentionally contact aliens? If we're not, why assume they are?

Not only that, we've sent Voyager out there to meet them!

So we have sent such a signal. How long did it last? If an alien race wasn't listening at just the right time, they'd miss it. On the other hand, if they had equipment that could pick up normal TV/radio signals, they could detect us any time.


Again, consider aliens trying to detect us from a distant starsystem. Are we sending out high energy signals to intentionally contact aliens? If we're not, why assume they are?

I dont know if our signals are sent for alien listeners since that would compromise the international security of the home planet. That is why that missle to explode on that asteriod was soo far away from here.

I dont know if our signals are sent for alien listeners since that would compromise the international security of the home planet. That is why that missle to explode on that asteriod was soo far away from here.

Let's not forget when talking about listening for alien life that even if aliens had put out TV of their own we not hear it unless they were very close (only a few light years away).

The power of antenna needed to listen in is like a million times that of SETI just to checkout this neighborhood of stars (up to 100 light years away).

A form of evolution did occur here on Earth. But did it all come from scratch? That is something like a 1 in 4,000,000,000 chance based off the complexity of life and how easy it would have been to interrupt this. Even the odds are against this all getting started here on Earth without something else helping it to get the foothold life has today. But I guess there is quite some pride to the idea that we got going all by ourselves on this little planet.

A form of evolution did occur here on Earth. But did it all come from scratch? That is something like a 1 in 4,000,000,000 chance based off the complexity of life and how easy it would have been to interrupt this. Even the odds are against this all getting started here on Earth without something else helping it to get the foothold life has today.
The odds are almost certainly much lower than that, given the conditions that existed on Earth in the Hadean/Archaean periods. Here is an article which looks at the stages before the hypothetical RNA world;
http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0030396
But for Morowitz, the most exciting development in the metabolism-first camp, “the really new idea,” is that small organic molecules, such as amino acids, can catalyze the formation of other small organic molecules, such as nucleic acids. “This has emerged only in the last two years,” he says. This view has found strong support from a new finding published in the journal Chemistry in August 2005, which indicates that single amino acids can catalyze the creation of sugars from simple starting materials with enzyme-like specificity.

“What has emerged is a very strong self-organizing principle,” says Morowitz.
It may be the case that many terrestrial-type planets have some or many of the pre-requisites for the emergence of life. If so we might find that life is widespread.

Another study suggests that life might spread from star to star in the very early stages of a star's existence, when the stars are close together in a cluster. One study I have read suggested that such a transfer might occur on average once in every cluster; if so we might find even more life-bearing worlds out there.

The sun has made a couple of orbits around the milkyway in it's existence, are their any know family of our sun (ones that where made out of the same clouds?)

The sun has made a couple of orbits around the milkyway in it's existence, are their any know family of our sun (ones that where made out of the same clouds?)

Why?

So we have sent such a signal. How long did it last? If an alien race wasn't listening at just the right time, they'd miss it. On the other hand, if they had equipment that could pick up normal TV/radio signals, they could detect us any time.

I don't think we've recieved any alien replys yet. However, if I were an advanced alien living on another planet in a nearby star system and I happened upon an old 'I Love Lucy' T.V. rerun sent out from planet Earth about 60 years ago, I would probably switch channels.

I don't think we've recieved any alien replys yet. However, if I were an advanced alien living on another planet in a nearby star system and I happened upon an old 'I Love Lucy' T.V. rerun sent out from planet Earth about 60 years ago, I would probably switch channels.

Even the later porn channels?

If I was a alien and could somewhat be persueded to visit then watching some relevant terrestial movies would certainly change my mind. Name one movie/tv serie where there is no probing, no killing, no sex or humans being superior, with aliens.
The entire earth is broadcasting piss of unles you wan't to be fucked or/and killed. Perhaps to only thing stopping us from first contact is a PR problem.