Wednesday, May 9, 2007

is there other life in the universe?

i believe life... in some form... exists somewhere in the universe other than just on earth. the universe is just too big for us to be the only life!! we developed on one planet, among nine eight planets that orbit around one star in the milky way galaxy which harbors ~400 BILLION other stars. the milky way is only one galaxy among the BILLIONS of galaxies in the universe, each containing BILLIONS of stars. any of those stars could have planets, but planets are really hard to find!

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 neck arm of the milky way, in space vehicles that travel very very fast!!

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!!

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