Aliens!

There's an awful lot of our galaxy that we don't know anything about though. The thing is big. Really big. Light from the other side takes some 75000 years to reach us. 75000 years ago we were a bunch of primitives, not emitting anything that would distinguish us as intelligent (although we, together with other life, affected Earth's atmosphere, and that might have been detectable spectroscopically). So I'm not sure that the lack of evidence means much yet, we haven't nearly searched long or hard enough.

And the galaxy isn't just big in space, it's also big in time. Billions of years. Depending on how you count, humans have been around for, let's be generous, 100000 years. If we assume that today is a random day during which we exist, then there is a 95% chance that today is not within the first 2.5% of our existence and not within the last 2.5% of our existence. So, assuming we don't know anything else, there is a 95% chance that we'll be around for between another (2.5/97.5*100000=)2564 and (97.5/2.5*100000=)3.9 million years. Do the same thing for our technological civilisation, which is some 5000 years old, and you get a range of 128 to 200000 years. The oldest star in our galaxy is some 13 billion years old, so even with the first numbers we have a 95% chance of being around for only 0.03% of the current age of the galaxy. And if you look at the second number and conclude that a technological civilisation will often not last longer than 100000 years, and that that is of the same order of magnitude that a signal takes to cross the galaxy, there may be all sorts of alien civilisations, but we may never get the chance to talk to them.

As for life that we wouldn't recognise as such, one way that that could happen is if it functioned so slowly that we wouldn't recognise it as a changing thing. It seems to me that change should be part of any definition of life.

What do you mean by "alien planet"? Any extrasolar planet or a planet that is inhabited by alien life?
The number of confirmed extrasolar planets is quickly approaching 600 (564 currently) http://exoplanet.eu/catalog.php with another 1200 or so possible candidates from the Kepler mission alone! And we have not even discovered a fraction of planets yet!


I would say the chances for this are lower than winning the lottery.

I say they definitely exist somehwere in the Universe, yes. Yesterday there was a clear night sky and I finally identified half of Draco. (I will identify the whole of Draco tonight, if weather permits.)I also identified Cassiopeia along with Ursa Major and I had the feeling that although I probably checked out only a small part of the night sky, we are NOT alone in this Universe!

I've never been able to identify the constellations. Of course, maybe that's because I've lived in big cities almost all my life. . .

SuperShuki, I too, wonder how it is easier to identify them: with light pollution in the area I saw them or in overseas where I can see millions (it seems) of stars of all sizes, colors and brightness in the night sky and it becomes too confusing!
The night I was outside I was fortunate because there were no clouds whatsoever and due to light pollution, not many stars.
Ursa Major, Draco and Cassiopeia (along with Ursa Minor, Orion. etc.) is visible even if there is light pollution in my area.
Draco was a bit hard to follow, I still have not finished spotting the whole dragon! I had my Astronomy book as my guide.

I would agree with Sandra with the modification that we are the only technological species living in this galaxy at the moment the Drake equation has been mentioned in this thread but not the Fermi paradox

https://secure.wikimedia.org/wikipedia/ ... mi_paradox

Lourens has given us some numbers on this galaxy and being aware of them before they make me think that this galaxy is too small in relation to the speed of light for it to be likely that any other technologically sentient civilisation is sharing it with us. Given the examples on this planet of civilisations either expanding or crashing and burning one way or another either a technological civilisation will expand thru and upgrade the real estate of the galaxy it is in to fit its purposes (We have so far not seen any evidence of this anywhere in this galaxy or any others) or they die off for one reason or another.

Given the numbers involved it seems unlikely that we are the first and given its only taken about a hundred thousand years for our particular brand of ape to go from the flint tool to primitive space tools a blink of the eye in age of the universe terms it seems to me likely that most tech civilisations manage to kill themselves off before they manage to get a viable breeding population off their primary planet.

So i suspect that the answer for the Drake equation is less than equal to one and will be until we or some other species manages to set up a viable breeding population in a stellar system ideally about 1000 light years from its home one.

Given that more and more we are finding planets within the habitable zones of stars, and the more accurate our instruments become, the smaller the planets we can detect.

As far as I understand, if the chemicals necessary are available, if there is water and a source of energy (heat), then life can arise.
Earth is an example of just that happening. Maybe it isn't as unlikely as some say.
Well. If they find some form of life on Europa, then we will have evidence of the variety of circumstances under which life can arise.

I would like us to encounter some form of sentient life. But even if we find microbes or a pretty flower on another planet, that would be exciting.


Studied astrobiology last semester at university, this was the text book:
'Life in the Universe', Shostak, Bennett and Jakosky.

With the amount of organic molecules we have already spotted around our galaxy already i am quite willing to believe that we will eventually find examples of many forms of life thru our galaxy if we survive long enough to do so we even may find archaeological examples of other extinct tech civilisations but as i said above i think that given the size of our galaxy in relation to the speed of light and the amount of time its been around its seems likely to me on the balance of probabilities given the age of our galaxy that we are the only tech civilisation existent at the moment in this galaxy. I would like to be proved wrong and be willing to shake the hand or tentacle of any LGM that i might encounter provideing of course S/He/It is not carrying a signed copy of "A Hundred ways to serve Man" written by their Jamie Oliver equivalent

I think if we look hard enough we may even find life on Mars or Europa tho it may only be of bacteria level the anomalous Methane levels on Mars and the colours of the cracks in Europa's surface ice sheets still give me hope that we might still find something in this solar system and if we do then the Goldilocks zone could be considerably expanded increasing the likelihood of more sophisticated lifeforms elsewhere but not i think other tech civilisations.

Me personally i would give our fellow apes dolphins and dogs the benefit of the doubt on a certain awareness and intelligence but dipping a stick into a termite mound is not a tech civilisation IMHO.

Intelligent Aliens i also have doubts along with Intelligent spammers he say looking at your sig.

The definitive answer is this: The numbers involved essentially guarantee that sentient life is not a singular occurrence in the universe. However, the spaces and times involved virtually guarantee no contact among them, or at very best allow for long-distance communication with vast intervals between one response and another. Even this is a low probability given the brief timeframes in which civilizations close enough to contact each other in space would be technologically and psychologically compatible enough to communicate.

The chance for contact of a sort, however, increases substantially if we examine the possibility of astro-archaeology - finding abandoned technology of long-gone civilizations either through remote-sensing or direct exploration of celestial bodies. Finding anything in this solar system would be a very low probability, but the odds would increase with a wider sample of star systems.

I don't think it would be at all going out on a limb to state that there are probably ruins all over the galaxy, in far more profusion, and across far wider spans of time, than the relative handful of active civilizations currently living.

Well, that's assuming that there's no way around the light speed speed limit, for example, wormholes, or the Alcubierre drive. Considering the exponential rate of technological advancement of our times, it could even happen in our lifetimes.

Sort of the other way around - the current fact is that there is no way around the light speed limit, so we would have to assume there is to propose futures that utilize such technologies. While I am optimistic, I find it best to examine the future from a least-assumptions perspective. Trust me: I've looked deeply enough even at cautious futures to know that they are every bit as amazing, just slower to develop.



This is a misunderstanding. Only certain limited metrics of technological advancement - e.g., the number of transistors in a given processor space - have exhibited exponential growth, while macro-technological development has either grown linearly or in asymptotic curves as their underlying technologies reach maturity and fail to make radical leaps. The odds of superluminal space travel being available within the lifetime of anyone alive today are vanishingly small - I see no basis for it.

Agreed. Look at battery tech advancement - very slow - look at nuclear fusion - very slow - building construction - very slow (concrete was invented by the romans) - banking technology - hmmm, backwards -

Semiconductor and computer tech seems to be one of the few areas with rapid advancement - but would like to hear of others areas!

James

Ray Kurzweil wrote a bunch of books on this topic. He refers to information technology growing exponentially, and writes that more and more technology is becoming, at base, information technology. http://www.kurzweilai.net/

Yes, a lot of stuff requires semiconductors, but that doesn't mean that the industry itself is advancing at the same rate - just that they may be able to do the same stuff faster and cheaper.

It's real innovation that is becoming less common. We still use rockets to get to space - IT doesn't create a new propulsion system - it's just makes the ones we have easier to design, build and run. (ref: SpaceX). However, it won't make it cheap enough for everyone to go in to space, that requires something else entirely.