I think that depends on how you are approaching the subject. For the great majority, proof will come when all mankind sees the writing on the wall,
and has the graffiti of suppoistion and speculation confirmed by science...
Originally posted by Druscilla
1. Safely distant unambiguous radio signal detected
If by safely unambiguous, you mean a radio signal that bares unmistakeable hallmarks of being devised by an intelligence of some kind, then why not?
The only difficulty here would be, would we recognise such a thing if it came? There is a chance that a sufficiently complex signal could be lost in
the noise of the stars. Therefore the transmission would have to be directed toward us to have a hope of getting through. Furthermore, it is unlikely
that we would be able to discern all but the most basic of proof of its intelligent origin. Also, one must remember that the first broadcast an alien
intelligence is likely to have picked up, would have been of Adolf "may his name be forever cursed" Hitler, pontificating and hating on people, so its
unlikely any neighbor we would want to meet, would reply to such drivel, save to blow us all to hell to keep our hatred in the past, and prevent us
from infecting the cosmos with our unreasoning xenophobia.
Another sigificant difficulty, will be that there will be an inevitable language barrier, and without evidence to say that the alien language will be
decodable for us, there is every reason to suspect that only the most basic mathematical correspondance would have been sent, or could be discerned.
Then you have the issue of how long such a signal would take to reach one star system from another, which could mean that the originator of the
messege has long since given up, ceased to send, and/or has ceased to exist.
2. Microbial life, and/or simple life found on Mars, or somewhere else in our solar system
Again, it depends what you are intending to confirm. If they found microbial life on Mars (about which there has been recent speculation), then all
that would confirm in fairness, is that there are microbes on Mars. Even if it were proven that the microbes were of martian or non terran origin,
rather than being contamination from the lander/rover, all that would prove and confirm, is that Mars has microbial life, living on its surface. One
might deduce from that information, that Mars HAD a flourishing ecology at one point, but there again, it might just make a better case for the
argument, rather than being proof itself.
3. Aliens show up in the open to say "hello", destroy us, harvest us, enslave us, make friends, whatever.
Well of course that would be confirmation, but is pretty unlikely at this point, from what facts there are on this topic.
4. We find/locate/detect a derelict, or even active alien probe
I would be very suprised if we had the fortune to stumble across something like that, and if we DID, I would be even more suprised if it came out into
the public domain. There is much speculation that such things have occured before and been hushed up, so as a confirmation it is sketchy,because
confirmation to my mind would be by a method that is inclusive and open.
5. Bio-SETI finds unassailable evidence we were engineered by aliens
If that was remotely on the cards, then we would already have to have evidence that they existed in the first place (of which there exists none, and
if found would render any confirmation centering around that line of thought moot, since alien life would already have been proven by the EXISTENCE of
aliens to do the genetic manipulation in the first place) and examples of thier work in DNA manufacture, to compare our own DNA to. We dont have
either, or at least, if we do, then most of us dont know it, and it is therefore of little use in confirming anything to the wider population of the
planet, which is the only aim of searching for intelligent life in the universe, to answer for all mankind the big question, are we alone out
6. We find xeno-archaeological remains on the moon, Mars, an asteroid, somewhere: abandoned facilities,listening/transmission/detection/sensing
equipment left behind, artifacts of non-human origin.
That would seal the deal, but is again reliant on our being TOLD about anything of that nature. The best confirmation, will come when something that
literally cannot be debunked, re-imagined, questioned or refuted comes to the attention of all mankind. Individuals knowing something is of no use in
this regard unless the truth is told to all mankind. I myself refuse to believe anything that I cannot touch, test and examine for myself, save of
course for matters of faith. However, faith has no place in what should be a purely scientific area of study.
I am hopeful however, that we will see such a thing in my lifetime, though I have no reason to suspect it will be so.
edit on 1-12-2012 by
TrueBrit because: Corrected quote error.