03 Mar 12
Originally posted by twhiteheadOur signals would not be detectable in another galaxy, even close ones like the magellanic clouds which at 175,000 ly away wouldn't even receive our signals for another 175,000 years because our wavefront of RF is only 200 ly across, so it is only in that sphere 200 ly across could ANY civilization no matter how advanced even if they are only 125 ly away because our signals would not have reached them, even if they had a dish the size of the entire solar system.
Yes, I think it would. I think it would be a very significant find. It would either tell us that life travelled from Mars to Earth or vice versa, or that life is very common in the universe.
But do you get my point that even if we have terrabytes of data (with no signal found) it may be insignificant if it is only covering a tiny proportion of the univ ...[text shortened]... tly observable outside our own solar system and we haven't even rule out it existing on Mars.
And of course you are right we have only looked at a small portion of our galaxy. I don't think we could detect anything from another galaxy even if there was a signal to detect unless WE had a dish the size of the solar system. Even if we detected a signal from another galaxy it would strictly be one way because a return signal would take millions of years.
We would only have a chance at dialog if they were within ten or twenty light years, statistically unlikely, if there are other civilizations in our galaxy they are probably more like 10 thousand light years away, and if that was the average distance between civilizations, there would be room for a lot of them in our galaxy, since it is about 100,000 ly across. There could be a dozen such and we would never know unless their signals, assuming they were radiating RF of any wavelength, were in our neck of the woods.
I have heard it said we could detect ourselves with our own equipment on the other side of the galaxy if our signals were present there.
So it boils down to a matter of luck.
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04 Mar 12
Originally posted by KazetNagorraNo, and again, that's my point: we do not have nearly enough knowledge to make anything more than guesses. Not estimates, not even guesstimates - pure, unadulterated guesses.
That's not quite true - we know some things about what other planets look like, and we know approximately what ingredients are required for life. So even though our knowledge of planets, particularly outside our solar system, is limited, we can make guesstimates of the number of planets expected to have life on them. You make it sound like it's a metaphysical question, but it's not.
And you're right that it's not metaphysical. If we had sufficient data, we could make a proper estimate. But we don't. Not by a long shot. Any discussion of non-terrestrial life is just guesswork.
Richard
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04 Mar 12
Originally posted by SoothfastSince elephants exist on Earth, they are quite likely to exist on other planets.
I despise these kinds of vacuous arguments people try to make. What the hell is your point? The reasonable position for a scientist to take regarding the existence of life elsewhere in the universe is clear: since life exists on Earth, it quite likely exists elsewhere.
Since RHP exists on Earth, it is quite likely to exist on other planets.
Since you exist on Earth, there is a Vulcan you.
No. Stop guessing - start looking.
A couple of decades ago or so someone like you would have been running around in rags accosting pedestrians with spittle-foamed rants about how we don't know that other planets exist beyond our solar system, and anyone who said they did exist is "letting fear master their science" or some similar twaddle.
Nice personal attack, matey. Stop reading your own mind and start reading what I actually wrote, not what you would like me to have written.
Science is all about speculation. Without speculation there cannot be theories, and without theories there cannot be experimentation.
Of course. But I would like some slight acknowledgement that speculation is speculation, and not some post-modern certainty.
We can speculate about the existence or non-existence of life outside Earth all we want. In fact, we should. And in fact, we should keep looking for it. But we should also be honest about it: we are speculating, and we are looking for something we neither know is there, nor know is not there.
Again (*sigh*) I do not, repeat NOT, claim that there is no life outside Earth. What I claim is that we have no reason to believe that there is, any more or less than we have reason to believe that there isn't.
And yes, that uncertainty in itself is reason enough to keep looking.
Richard
05 Mar 12
1 edit
Originally posted by Shallow BlueIf life exists here, using the same exact atoms that exist throughout the entire universe, then the odds are not exactly the same as assuming the possibility of life elsewhere is exactly the same as assuming there is no possibility of life elsewhere. The fact that we know there is life here tips the scales of probability quite a bit. We are in no special area of the universe or even our own galaxy. So the odds a bookie would pay has to go up about the possibility of life elsewhere in our galaxy.
Since elephants exist on Earth, they are quite likely to exist on other planets.
Since RHP exists on Earth, it is quite likely to exist on other planets.
Since you exist on Earth, there is a Vulcan you.
No. Stop guessing - start looking.
[quote]A couple of decades ago or so someone like you would have been running around in rags ac e isn't.
And yes, that uncertainty in itself is reason enough to keep looking.
Richard
And of course we are looking. Looking for signs of life from every probe we have sent out into our solar system and more to come. We see evidence for the possibility of life on some of the moons of Saturn and Jupiter, of course not life found but possible artifacts of bacterial life at least.
The odds are life will form wherever a halfway decent supply of energy exists.
For instance, in the bottom of our oceans, thermal vents brings up water that is searingly hot, hundreds of degrees C. Around those vents new life forms. That is well known. What is not so well known is we recently found life forms around vents that have shut down for centuries, so the vents jump start life down there and when the vent stops, the life forms mutate to survive anyway.
05 Mar 12
Originally posted by Shallow BlueYou again bring me to ask: What is your point? I don't think anyone here would disagree that speculation about extraterrestrial life is just that: speculation. I and others may think it "highly probable" or "virtually certain," but would readily admit that 100% certainty is not a given. You're tilting at windmills that aren't even there.
Since elephants exist on Earth, they are quite likely to exist on other planets.
Since RHP exists on Earth, it is quite likely to exist on other planets.
Since you exist on Earth, there is a Vulcan you.
No. Stop guessing - start looking.
[quote]A couple of decades ago or so someone like you would have been running around in rags ac ...[text shortened]... e isn't.
And yes, that uncertainty in itself is reason enough to keep looking.
Richard
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07 Mar 12
Originally posted by SoothfastMy windmill is people who state, in all earnest, that since there is only very little evidence against the existence of life outside earth, it is reasonable and scientific to believe that there probably is life outside earth, or sometimes even that there must therefore be life outside earth.
You again bring me to ask: What is your point? I don't think anyone here would disagree that speculation about extraterrestrial life is just that: speculation. I and others may think it "highly probable" or "virtually certain," but would readily admit that 100% certainty is not a given. You're tilting at windmills that aren't even there.
The former attitude at least has been stated explicitly in this very thread, so don't say it's non-existent.
Richard
08 Mar 12
Originally posted by Shallow BlueIt is generally logical, and properly scientific, to presume that if an event has been observed to occur in one place in the universe, then it may occur in other places. This is in contrast to, say, the concept of a god, which has not been observed to occur even once in the universe in any scientifically verifiable manner -- quaint old tales of "miracles" that transpired millennia ago notwithstanding.
My windmill is people who state, in all earnest, that since there is only very little evidence against the existence of life outside earth, it is reasonable and scientific to believe that there probably is life outside earth, or sometimes even that there must therefore be life outside earth.
The former attitude at least has been stated explicitly in this very thread, so don't say it's non-existent.
Richard
12 Mar 12
An extraordinary and very lengthy list of factors that make our life possible could easily have been sufficiently different to make us impossible or to make us unrecognizably different.
Many of these can be discounted for our discussion since, while the multiverse position, say, accepts that the "laws" of physics for example can and will be different in other universes, we are only interested in our own universe for this discussion and in our universe, the laws are as they are throughout the universe. So in asking about life elsewhere, many of the factors favouring life can be taken as present.
We have narrowed the odds further by establishing that other planets certainly do orbit other suns, in immense (stupidly large) numbers. The prospect that there are planets which provide conditions comparable to those on earth is becoming quite acceptable.
Once we have a decent number of comparable planets (and I think we can say that we do, without yet knowing which ones) then the next thing to remember is that life is possible in quite diverse environments - such as a sulhpur rich, extremely hot vent deep under the oceon. We know this and we have found it on earth.
So whatever the stupendous odds may be against life having emerged on Earth, the fact is that those odds have been overcome by the way this universe is structured. The laws of physics are what they are and apply consistently across our universe. They can operate as well on many other planets as they do on our own. There are an awful lot of planets available for this to take place.
Then appreciate that - given certain conditions, then life is a reasonable product. These conditions may be surprising and rare, but they are perfectly possible and - as noted - they have indeed arisen on earth. Given the recurrence of such conditions (and allowing a range of environments in which they might arise) then life would be a reasonable expectation and indeed, one might feel surprised if it did not occur.
Life having started and survived, then the process of evolution would assuredly follow. It would be surprising if it did not.