i'm certain life exists *somewhere* in that vast volume of space, but that's exactly the difficulty in finding life.... there are so many galaxies and stars so where do we look? what do we look for? since we live on a planet, we can easily deduce that the best place to look is on other planets! as of today, we've detected 233 planets outside of our solar system and its cool that we finally found an earth-like planet that exists in a region around a star with a temperature to support liquid water!
life on earth has existed for 5 billion years but the universe is about 13.7 billion years old. some life out there could have just began in the last billion years or less, or some planets could have harbored evolving life forms for twice as long as the earliest known life forms believed to be on earth! that raises interesting questions about what life on earth might look like in another 5 billion years (assuming life survives this destructive period in human existence)! consider that only 65 million years ago, dinosaurs dominated earth's surface!
communication with extraterrestrial lifeforms is a whole other issue. our chance of "communicating" with anything out there (in my opinion) will result from another civilization communicating with us. we've been sending off electromagnetic signals for, lets say, 100 years. the earliest signals are now 100 light years away from earth in all directions. within that sphere there are only ~30 stars. the new planet we just found is about 20 light years away... so it has received our earliest transmissions and has had ample time (over 20 years) to send a light signal back our way. We havent received any signals from this or any other planet accoring to the SETI Institute. our (unintentional) early electromagnetic signals have only reached a few dozen stars among the buhzillions that exist in the universe... and thats traveling at the speed of light!
so.... thats why i say our best chance for communication is from another life form having sent out a signal at some point in the past. let's say there's intelligent life on a planet on the other side of the milky way... about 40,000 light years away. if we receive a signal tomorrow from this distant planet, the signal will have been traveling from that planet for 40,000 years! we are ready with our return signal (of course!), which we send out immediately. that planet will start receiving our original signals in 39,900 years and then in 40,000 years, they will receive our response specific to their message. then it will take them 40,000 years to respond to us, etc....
another (more hopeful) option is that they will have detected our presence thru light detection or exploration of our
my point is not to lose all hope of ever detecting another civilization... on the contrary, i think it is super exciting that we are detecting so many planets so rapidly right now!! my real point is that there *has* to be life out there somewhere is this unfathomably large universe of ours. probability says there should be life considering the volume and the fact that the chemistry that makes life possible on earth is extremely abundant throughout the universe. so let's keep looking and doing our best not to destroy our own successful and immensely special civilization while we are actively searching for those signals!!
A very hopeful and informative post, Amanda, thanks. I too share that feeling that with all those galaxies, stars, and now (finally detected) planets, this wonderful accident must have happened other places too, though with the small demonstrated sample size for life (N=1), strictly speaking it's a bit risky to extropolate! We should definitely keep looking for the signs of others out there, though I also wonder when the others may have gotten cable or optical communication or neutrino or tachyon communication or whatever. Could they be advanced but invisible unless they are trying to be seen (heard, detected)? This sort of discussion always reminds me of Sagan of course, which is also not a bad thing.
Hail to thee Pixie, this is the first time I've read your blog. I share your disbelief that this old planet should be the only one in the known universe to have life on it. It really isn't that unique surely. The abundance of the right chemistry, multiplied by the sheer volume of space and uncountable stars blows away any idea of uniqueness, so let’s keep looking and listening. The problem I think we're most likely to face is one of time, or rather the short span of time that is the evolution of the conscious beings that we would hope to communicate with. Life on Earth is only a few hundred million years old and people have only been around for a tiny fraction of the planet's existence. If the same is true of our neighbours, then we are relying on their existence to coincide with ours. Two simultaneous blinks of an eye out of an eternity. What are the chances of that? Sorry if that sounds pessimistic, but I'm out of chocolate.
On th eother hand:
Suppose the emergence of life requires 4 independent 1 in a million events, or 8 independent 1 in a thousand events. That gives a total chance of 1 in 10^24. With only 10^22 stars in the universe, it puts the probability for life at 1%.
As for aliens flying around looking for us, consider this:
The earth has hand oxygen in the atmosphere (the most spectroscopically obvious sign of life) for over 2 billion years, so the light cone for that telltale sign encompasses quite a few galaxies by now. We have had macroscopic life for half a billion years, and life on land for 300 million. So you'd think that if that interested anyone out there, they would have stopped by during that time, and not just in the last couple of decades...
I believe that not just life, but civilizations and technologies far in advance of ours are out there and well aware of us. Some incidents such as Belgian UFOs and cattle mutilations seem compelling to me. Sorry for wandering into lala land, but ETs seem like a natural explanation. I believe they do not reveal themselves in a major way because they prefer to avoid quicksand. Of course I could be wrong about all this. Actually I rather hope I am. An ET that mutilates cattle would not seem particularly friendly. Thanks for providing me the opportunity to post.
bigbob... youre out of chocolate :( that comment really gave me a chuckle... thanks!
chuck... not sure where you get the numbers of stars in the universe or the chance of life emerging, but its a good point that there are buhzillions of things that have to happen in the right order for life as we know it to exist... it's a good thing that there are about a buhzillion stars out there (i cant bring myself to attach any numbers!)! also, the oxygen in our atmosphere doesnt actually produce any light, so it would be very difficult for beings far away (or even nearby really) to pick up its presence. i like your idea that maybe earth was cataloged by some creatures 500 million years ago as having no intelligent life. i wonder if we'll get stuck back on the life-check rotation?
twixter... got a chocolatey twix to spare for bigbob? (hee hee) i have to disagree with you about the UFO's (why belgian?) and cattle mutilations.... nothing i've seen has ever convinced me that "ET's seem like a natural explanation". i highly recommend carl sagan's book demon-haunted world for more on that. thanks for posting!
I got that number from an astrobiologist's talk.
I agree with u that its certain to have life on other planets, and i extremely disagree with u CHUCK that 1% is the percentage ! OMG think about it !! all this space, is just for uss!!? i believe there are humans with more advanced technology.... !!!! it will be great to find them ! but we should make sure not to Open a war between us and "Them" heheh .. imagination !!
i'm first timer at ur blog.. and this post is simply amazing.
all of what u guys have said is definite. i might have a little addition too.. what if we are the ones smart.. what if the lives out there are less intelligent than us? dont u think that would be a reason too as to why we havent got any signs yet?
just a thought =)
One question regarding the electromagnetic signals we are emanating- does this information travel an infinite distance? What I mean is, are the paths of these waves altered by silly things like gravity? And blocked by the sun and other chunks of matter? Of the sphere drawn from earth with a radius of approximately 100 lightyears, how much of that sphere's surface area is actually being hit by the signals? Is patchy coverage optimistic? If unaltered transmission is a factor, perhaps the fact that we are moving relative to everything else while we continuously send data solves the problem?
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