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Burr

Aratus, it be wonderful if we both were here to see what "Differnce it would make" !!!!!!

As I've already pointed out on your previous thread, you are being driven by 'The Valence Effect'.   You believe that life on other planets would be beneficial to humanity.    You believe that aliens can show us a 'better way'. Therefore you get excited about every comment that supports that view. and get frustrated (angry?) by those that don't.    Obviously there is nothing wrong with finding one scenario more exciting than another.   That is human nature.  However it is intellectual suicide to allow it to drive your conclusions.

It would be interesting to discuss 'What difference would it make'.  But you will have to explain why you think it would be 'wonderful'.   It is by no means a universal point of view.

Centaur.   'To serve man' is indeed a possible scenario.   Let us consider the gorilla.     If some resource was required by our alien visitors, no thought to our habitat would be given if it got in the way.   If it came to supplementing their diet, then why not?   Gorillas are treated in exactly the same way.    Perhaps one day our survival will depend on some campaigning alien pressure group.  

I do believe in aliens. Because I don't think that WE  are the only existing civilization in this huge universe. There must be someone out there.

But I am neither so intelligent nor so educated on astronomy as you guys are. It is just what I think about it. And, as far as I know,  a lot of scientists are studying on this matter.

If I am wrong , please let me know.

- Anuva

Anuva1998

I do believe in aliens. Because I don't think that WE  are the only existing civilization in this huge universe. There must be someone out there.

Welcome to the discussion group, Anuva.

"Believe", "think" and "must" are not terms used within the scientific method.  Solid evidence linked by sound logic is what earns respect:  http://en.wikipedia.org/wiki/Scientific_method

Although i am also a firm believer that intelligent life exists beyond Earth it is only a belief. As Curt says, we have no scientific premise to work on. You can't even use the probability argument because we don't know the formula for such a calculation to be proven correct.

Baz.

My own view is that there is life elsewhere in the universe. The existence of extrasolar planets and suggestion that planets are much more common in our galaxy than we previously thought somewhat lowers the odds against.

There's no hard evidence that there are planets outside our own galaxy but it is certainly a fair assumption that if they can form in our galaxy, they can certainly form in galaxies similar to ours.

Although I'm rather unpopular for saying this and accused of being narrow-minded, I don't think intelligent life is prolific in the universe, so the chances of finding it in our galactic backyard is very low.

At this particular point in time, we know there are lots of planets out there and I think it is only a matter of time before we discover microbiological life elsewhere in the universe and quite possibly even in our own solar system.

We can put even the most cautious figures into the Drake Equation and show that there could be a few advanced civilisations in our own galaxy but the density is low, say one per million million cubic light years or less. This would suggest that if we assume that civilisations are evenly spread in our galactic backyard, that the next one will be (on average) 2 500 light years away.

At this distance, we'd have to wait 5 000 years for a reply.

Anuva1998

I do believe in aliens. Because I don't think that WE  are the only existing civilization in this huge universe. There must be someone out there.

Hello Anuva.

If your opinion is that life exists elsewhere in the universe, that is fine.   There is no right or wrong opinion, because at the moment we don't know either way.    Your opinion might turn out to be correct.    The discussion is really to do with whether we can take what we do know now and conclude the likihood of life forming on other planets.

You make the argument that the universe is huge.  In fact it is possibly infinite in size, or as near as matters.    On top of that is the possibility of multiple universes.     From this many people conclude, as you do, that whatever happened to form life here must have happened more than once.    I can understand your reasoning.     The problem is we really don't know the conditions for life to form.    There is no doubt that once it does form that life is pretty good at surviving, but the independent formation is big unknown.    

A nearly infinite universe might be the reason that life has formed on the Earth.  It maybe such an unlikely thing that it requires a huge number of 'chances' for it to happen once.    The chances of it happening twice in our universe might be infinitely improbable.

Or perhaps you are right, but it isn't good science to say 'must'. 

Thanks everyone. I will have further study on this matter.

- Anuva

There is another element to this.   Supposing there are 1000 civilisations in the Universe, equally spread out.   They would be so far apart as to be undetectable.    So there may be lots of life in the universe, but practically speaking we might as well be on our own.    The issues of alien spacecraft, first contacts or receiving radio signals would be just as if life was unique to the Earth.

Yes, I agree and would further add that 1 000 civilisations spread evenly even throughout our own galaxy would present similar problems.

I think open-mindedness means being open to all possibilities, not just one. I think the main scenarios are:

1. We are totally unique and no life exists outside our own planet

2. The universe is teeming with intelligent life

3. Life is quite common (say 1 to 10% of stars have planets and moons that contain life) but that only a very small number of ecosystems develop intelligent life and:

3a The Earth is the ONLY ecosystem that has produced intelligent life

3b Other ecosystems have produced life intelligent enough to send signals through space but  they are far enough to make communication difficult if not practically impossible

We don't definitively know the answer and I doubt if we will in my lifetime but I would say the "smart money" is on 3b. Forget about the Mars meterorite for a minute and consider that organic molecules have been detected outside our solar system. This is not definitive proof but certainly a strong suggestion.

We can't rule out the other possibilities and I'm open-minded enough to accept that but when you look as to how we evolved on Earth, one can only conclude that our evolution was been lucky to say the least to exist at all.

Don't forget the possibility that many other intelligent life forms may have developed, but that they have been separated by time as well as space.  Intelligent civilizations can be expected to have a finite life span in terms of longevity, so it is fully possible that many have come and gone, and that others may not evolve until long after human-kind is finished.

Yes, that is also true. We do not yet know how long a civilisation can last after developing the capability to send interstellar signals. Again, this is more of a guided guess but I would say that there's more civilisations that will come than those that have gone.

We know that life is far less liklely to develop in planets orbitting metal poor Population III and Population II stars (if not downright impossible), so we can deduce that there aren't many metal-rich stars older than the Sun. So any life around them would not be much more advanced than we are, unless it could have evolved more rapidly. We know that microbiological life took 3 900 million years to evolve into beings capable of sending interstellar signals here. Does microbiological life inevitably evolve to advanced life? I don't think so and it's not impossible that Mars may well turn out to be one place where it didn't.

Could a past civilisation have developed the ability to travel intergalactically? I'd say possibly but probably not en masse. We know that some organisms can live for thousands of years but can advanced life? I think it could be possible and it is also possible that our brains may be able to exist in cybernetic "bodies" in future so artifically extend our lifespan.

M44 : I wonder if there exist a computation, which could determine the probability of a successful propagation of intrelligent life forms, such as the one use by science here on Earth, but applied to, solar systems, galaxies, galactic clusters, and super of hyper clusters? This would reduce the occurrence of extinctions over time, if applied, and such a probibiliy can be calculated.

I can't remember it exactly but it's called the Drake Equation. Most of the values in it are estimates but even the most pessimistic estimates seem to suggest that we're not alone, although the chances are that we're alone in our own galaxy. The most optimistic estimate gives an average distance of 100 to 1 000 light years.

The other possibility is that other civilisations may receive our systems but choose not to reply.

M44 : Thanks for your reply, I'm familar with the Drake Equation, but my reference was to the nunber used on Earth which deals with the necessary residual population ( number) for continued survival after a near extenction. This number could determine the necessary nunber of populated planets, etc. which are necessary to span a contineous population within the universe.