"EARTHLIKE planets covered with deep oceans that could harbour life may be found in as many as a third of solar systems discovered outside our own, US researchers said yesterday."

Reported in the journal Science. A team from Colorado, Penn State University and Goddard Space Flight Centre Maryland used computer simulations of various solar systems forming. They believe that hot Gas Giants help in the formation of watery terrestrial planets like our own. This is further evidence that the rest of the universe is almost certainly inhabited.

Our own Solar System has a number of rocky planets. Earth is the largest terrestrial body although Venus is almost identical in size. Unfortunately it developed a runaway greenhouse effect caused by its dense atmosphere. Mars did once harbour oceans according to recent research.

Intelligence has survival value. The Octopus for example is an invertebrate and yet it has independantly evolved a twin lobed brain and is the smartest living invertebrate. Such parallel evolution is strong evidence for the development of intelligent life on other living planets in our Galaxy.

Research also suggests that the majority of other Earthlike planets in our Galaxy will be older than ours. This means that there is a statistically high probability of life more advanced than us having already evolved on numerous worlds. It is logical to assume that many of these races have already started exploring Space.

The biggest question asked concerning the possibility of sentient alien life has always been "Where are they?" as clearly we have not been visited within recorded history.

Australia was the last continent discovered by European explorers. Powerful seafaring nations were too busy fighting each other. Wars restricted the expansion of nations through attrition and resources.

Spacefaring civilisations would gradually colonise neighbouring Stars and expand their sphere of influence until they meet a challenging Alien race coming the other way. Then conflict follows. The winner will require time to recover before engaging in further exploration.

Just my own theory as to why we haven't had any visitors. Personally I think it's a good thing but inevitable we will meet them.

Wayne a strong possibility, yet it may not be the only one. It could mean other advance civilisations may also be in conflict with themselves or a close, (interstellar neighbour) and don't have the available resources for any long distance project. It could also be they're so different to us we don't recognise them, their transport or communication systems. There's many possibilities which are all fascinating, but it could be all possibilities considering the size of the universe.

You could also say we may have had visits which have led to certain primitive ideologies, or this planet was seeded to interbreed with native animals. Hence the reason some humans have the evolution gene and it appears not others. Or we could be getting accidental or deliberate visits from other dimensions, hence the appearance of alien and their ships looking just basic 3 dimensional machine and bodies as we may not see their extra dimensions.

Very interesting, I tend to lean towards every possibility and the probability they all may be wrong. I expect we may find out sooner than we realise, it's about now that our electronic and magnetic transmissions started only 100 years ago, would be reaching other planetary and galactic systems. If they are advanced, they would be able to detect our primitive attempts, but we may be not capable of understand theirs.

I hope you get a few interesting ideas from this thread as it appears you've wrote it to stimulate constructive thought, and not dogma.

Thanks for the informed reply. I'm also inclined to think every possibility likely. We have a bad tendency to talk in absolutes when philosophising about other intelligences. I believe this is the wrong attitude. To say that "they will do this or that" is to assume there is only one other Alien species of any consequence out there.

The ancients were just as blinkered as we are. Hardly ever seriously considering the possibility of external threats. Nearly all the great civilisations were guilty of anthropomorphism. They were the centre of the world and the universe. Nothing of relevance lay beyond their kingdoms. The Chinese, Aztecs, Aborigine, Indians etc all learned the truth only after bolder and more advanced nations invaded them.

The ancient Greeks considered the possibility that other Stars were Suns like ours with planets orbiting them. Suns which might harbour life and even strange "peoples". Then such heretical thinking was lost until the time of Galileo.

It is the nature of Life to reach out and expand into new environments. Sadly it is also the nature of life to ignore what we cannot see. Even when we know logically that something must surely exist since the odds against it our astronomical.

As an example we know that asteroid and comet impacts are a certainly yet we have taken no serious action to defend ourselves against such a threat. It is true that the chances of a dinosaur-killer striking us in our lifetimes is very slim, but the results of such an impact would be catastrophic. Up to 95% of life on earth could be destroyed.

A long period comet could hit us in the next second and we wouldn't even see it coming. Humanity would vanish. As if it had never existed.

WayneSmith: There's a heap of conjecture and jumping to conclusions in your posts.

Firstly, you're talking about computer simulations of solar systems forming. Do we actually know, completely for certain, that one third of planets are Earth-like? Even if we do, what does this actually tell us?

Parallel evolution on our own planet is evidence for life on our planet. It has nothing to do with life on other planets as far as we know. Until we find evidence of life on other planets, how do we know that there aren't anywhere from one to hundreds (or more) of unique factors that have led to life on this planet, and this planet only? It could be a lot more complex than we realise.

Planets being older than our own is no prediction for more advanced life, let alone spacefaring life. By analogy, homo sapiens is "younger" than a whole lot of other species, yet is more advanced. Likewise, European civilisation is "younger" by a long shot than many indigenous cultures that didn't get past the stone age. Perhaps life (if it exists) on other planets never got past the single-celled organism stage.

If intelligent life does exist, who would say it would run into conflict with other intelligent life? That's anthropomorphism that is completely unfounded.

I'm not saying you're necessarily wrong, but I don't think what you've stated is either good science or good philosophy. I think it's important that people don't let their enthusiasm run away with themselves or science and philosophy become part of the same realm as religion, and ultimately, that doesn't help the endeavour.

Statistically I'm more likely to be correct than false. To ignore a reality simply because we can't see it is to pander to superstition and anthropomorphism.

It's all theoretical but then so was relativity. Math doesn't lie.
http://www.scienceagogo.com/news/20060807214941data_trunc_sys.shtml

It tells us Earth is not unique. From Black Holes down to sub-atomic particles mass is relative to number. Specks of dust are more plentiful than asteroids ok. Why would earth sized bodies be exempt from the equation?

Parallel evolution is life repeating the same designs. The Dolphin, Ichthyosaur and Shark. Bats, Birds and Pterosaurs. It is not "evidence of life on Earth" but evidence that nature repeats itself.

"how do we know that there aren't unique factors that have led to life on this planet?"

Such as? Tribesmen once laughed at the idea of 'bacteria' or the Earth not being flat. Our Earth is orbiting a very average Star.

"It could be a lot more complex..."

The moon could be made of swiss cheese if we dig down a little further.

"Planets being older than our own is no prediction for more advanced life.. "

Every ecosystem will evolve at its own pace. On average the older planets will have more advanced life.

"By analogy, homo sapiens is younger"

Our closest relatives the other Apes are the next highest intelligence on Earth (except perhaps for Dolphins).

"Perhaps life on other planets never got past the single-celled organism stage."

Many haven't and many probably have. Seems rather bigoted to assume every other planet in the Galaxy is backward.

"If intelligent life does exist, who would say it would run into conflict with other intelligent life?"

Conflict is what drives evolution. Alien nations will be even less compatible than human nations.

"..enthusiasm run away with themselves or science and philosophy become part of the same realm as religion...doesn't help the endeavour."

Thinking that other intelligences are peaceful is deifying them and contrary to all knowledge. Aggressive species become top dog on Earth. We are not vegetarians.

WayneSmith: You're totally missing my point, which is that we don't know one way or the other. At this point, it's conjecture, and to try to state that as scientific fact is detrimental to science.

"Statistically I'm more likely to be correct than false."

This sums your position up perfectly. There's a difference between being definitely correct and what you're espousing. Furthermore, you're actually misquoting that article:

"...MAY harbor Earth-like planets...QUITE LIKELY that these Earth-like planets would have deep oceans with the POTENTIAL for life." [Emphasis mine.] No one except you is jumping to the conclusions you are.

We don't fully understand the pre-conditions for Earth's life, and we can't recreate them. Therefore, we can hardly extrapolate about them to other planets. Your point about the moon is a strawman.

"Such as? Tribesmen once laughed at the idea of 'bacteria' or the Earth not being flat. Our Earth is orbiting a very average Star."

There have been other predictions in the history of science that were way off. Until the application of the scientific method, any idea is a conjecture or theory.

I'm not sure what you're saying about apes and dolphins. What I was saying is that our own evolutionary track (as a culture and as a species) is quite young, so age doesn't necessarily have anything to do with advancement.

"Seems rather bigoted to assume every other planet in the Galaxy is backward."

I didn't say it was. No one knows one way or the other yet.

"Conflict is what drives evolution. Alien nations will be even less compatible than human nations."

Inter-species conflict isn't the only evolutionary factor. We know nothing of other species' social psychology (if they do exist). Conjecture.

"Thinking that other intelligences are peaceful is deifying them and contrary to all knowledge. Aggressive species become top dog on Earth. We are not vegetarians."

This is irrelevant to your quote of mine.

You're the one making assumptions. Once again, my only point was that we don't have enough information. Stop saying I'm assuming things when I'm not arguing for or against any of these points.

"You're totally missing my point,"

Not at all. Your point was "we dunno"

"...which is that we don't know one way or the other. At this point, it's conjecture, and to try to state that as scientific fact is detrimental to science."

Human beings are smart enough to work on fractal facts. We can make educated guesses based on what we do know. Conjecture and science go hand in hand. Theories require an original hypothesis before any evidence is even gathered. The odds of me being right are frankly higher than my being wrong. The consequences of my being right demand that we take such possibilities seriously.

"No one except you is jumping to the conclusions you are."

Absence of evidence is not evidence of absence. Most scientists agree that we are not alone. Asimov was quoted as saying "wimps don't become Top Dog".

"We don't fully understand the pre-conditions for Earth's life, and we can't recreate them."

Amino acids have been created in laboratory tanks. The whole Earth was once laboratory tank! Life was inevitable. It appeared almost immediately.

"Until the application of the scientific method, any idea is a conjecture or theory."

Science has its flaws. It is not perfect. Some things must be analysed in relation to what we know and educated guesses made. Most scientists now believe life in this universe to exist.

"so age doesn't necessarily have anything to do with advancement."

Age is a factor. We are talking about billions of worlds. Averages must be employed. Its commonsense that more advanced life than ours must exist if we are not alone in this universe.

"Inter-species conflict isn't the only evolutionary factor."

Its the main one. Others are environmental challenges.

"We know nothing of other species' social psychology (if they do exist). Conjecture."

Again parallel evolution tells us otherwise. Even if only one percent of spacefarers were aggressive they would overwhelm and destroy the 99% who are pacifists. Ofcourse its more likely to be 99% being dangerous carnivorous survivor types like us.