UK folks - Horizon tonight - Are we Alone in the Universe?

[Neil]

http://news.bbc.co.uk/1/hi/sci/tech/7275370.stm Horizon: Are we Alone in the Universe? is on BBC Two at 2100GMT, Tue 4 March or afterwards from BBC iPlayer Although it is almost certain life exists around the galaxy, my fear is:- a) Complex life arising is far more unlikely than we imagine - There are so many coincidences piled on coincidences that allow us to live! b) How many complex life forms then terminate themselve by one method or another - We're trying pretty hard and could add to this list in the next 100-200yrs! c) How many of the species given (a) & (b) happen to exist during the same time frame. d) Communication is far far harder than we imagine - SETI is still looking!! e) Space travel is far far harder than we imagine - Travelling at speed in space is not easy! And far far more so with passengers!

[SymphonicX]

My beef has always been with the notion that aliens will be human-like and function both politically and socially...personally I think if we do discover alien life, it'll be in the form of bacteria, plants or at very very most a small lizard like animal. You're right about co-incidences, but as the universe is so big there literally is infinite possibility - but constricting the possibilities down with logic makes sense: if somehow they are self aware, intelligent alien lifeforms, the chances are it's so unfathomably far from us that we'd never meet or discover each other. the building blocks of life transcend the gulf of space...therefore any alien life could easily mimic our own, they would have to, for life to form - the chances of this being within a reachable, or even studiable distance? Very slim indeed...the chances of them somehow having the ability to break the laws of physics which we barely understand and simply cannot defy? very slim. They would be part and parcel of very similar limitations at best - the only saving grace is that if they are a species that has survived longer than any species on this earth, and have reached various levels of understanding of the universe, to the point where they are able to manipulate time and space itself...very unlikely. So in short, if there are aliens, I seriously doubt they'd be intelligent or advanced in any way. if they WERE...the chances are their evolutionary steps are completely different which would make communication practically impossible, in much the same way we can't talk to dolphins..

[Terran]

Although it is almost certain life exists around the galaxy, my fear is:- a) Complex life arising is far more unlikely than we imagine - There are so many coincidences piled on coincidences that allow us to live! b) How many complex life forms then terminate themselve by one method or another - We're trying pretty hard and could add to this list in the next 100-200yrs! c) How many of the species given (a) & (b) happen to exist during the same time frame. d) Communication is far far harder than we imagine - SETI is still looking!! e) Space travel is far far harder than we imagine - Travelling at speed in space is not easy! And far far more so with passengers! A) If we find life within our own solar system I think that would add significant evidence that "life" is a common emergent property given various chemical conditions. Meaning, that simple life would be a common feature throughout the universe. We still do not have a great understanding for the way solar systems develop so many of these "coincidences" you refer to could have actual mechanisms that aid in their development making it more than a matter of chance. For example even within our own solar system many of these "coincidences" exist on other planets and moons, if it were only a matter of chance one would expect the bodies within our solar system to possess less of these characteristics that we attribute to the development of complex chemical reactions(required for life). I know we have talked about this particular topic before so Im not sure If we want to revisit it in full..... B)Hmm...I suppose this could be an issue....but if we killed ourselves it would not mean life on the planet would disapere ...we could not even do that with all our nuclear bombs combined... The life that remains would evolve into more complex life and fill various sorts of ecological niches....maybe even one day after various extinction events and millions and millions of years intelligent life may make another appearance. Given the distances we are talking about if we find intelligent life lets say from some sort of signal by the time we receive the message the species might have already gone extinct....and by the time our responce signal gets to their planet another intelligent species may have already evolved to take over that niche...or its like the land of the dinosaurs and no one is there to receive the message.... C) This made be stratch my head....because like looking out into space is like looking into the past...for both humans and "others"...no one thing anywhere exists in the same time frame as something else anywhere...its all relative....Time is an illusion..... D) Too true...unless we figure out a better way.... E) Well true...but.....thats not really how I see the potential future of space travel and "humans"...the Singularity .....Given certain technological advances....Human's become indistinguishable from machines so much so that the human consciousnous exist as data within machines of our own building....Life spans are indefinite but a given consciousnous is not immortal....Space craft can be sent out into space traversing the huge distances and while it will take huge periods of time for these space craft to reach their various destinations once they do consciousnouses can be sent across the distances of space as light information and loaded onto the ship(so a consciousnous moving at the speed of light).... These ships will have manufacturing equipment aboard so that once they reach their destinations they can start building various infrastructure and things.........So sending these manufacturing ships out into space will be like building galaxy highways....and since lifespan is indefinite the time scale is managable.....

[Mike70]

kind of interesting timing that this show is going to be on so close to cassini's ultra close approach to enceladus- one of the prime candidates for life in the solar system because of the unquestioned presence of liquid water. on the 12th of Mar cassini is going to come within just 23 km of the surface of enceladus. yes you read that right it isn't a typo 23 km. there is subsurface water on enceladus that is being sprayed into space through some form of water volcanism. the real interest that enceladus is such a hot topic of study right now is that mixed in with the water (actually ice particles as it is exposed to space and freezes) are organic compounds (organic meaning based on carbon). so you have both liquid water and very interesting chemistry happening as well. here is a link cassini's homepage: http://saturn.jpl.nasa.gov/science/m...s.cfm?pageID=5 here is a pic of the water/ice jets on enceladus: