PrkWd.
You mentioned doing the math, and figuring out how many planets could possibly have life on them. While there may be more than a number can represent, conditions for the most part do not favor the growth of life forms.
There is a developing science behind finding extrasolar planets, extrasolar systems, and what it takes to sustain any form of life. Even though our planet detecting abilities are still in there infancy, there are several things we can deduct from teh little information we have found.
Of course there are infinite amounts of planets grasped by a stars gravity. But you have to consider alot of other things than the number of planets. The planetary systems stability. For example, look at Pluto. Its orbit is highly elliptical, It has been "Slung" by another massive body at one time or another, possibly Neptune. Most systems found have planets with extremely elliptical orbits. One that when computed out, only spell doom for the planet. Those large bodies, and there elliptical orbits make the possibility of there being terestrial planets like earth in that system...Extremely slim. If there are/were, more than likely they wouldnt have the time neccassary to sprout life before being destroyed or flung out.
Sure, there are countless stars alone in our Milkyway, but.....Alot of them have some charectoristics that make it hard to support a stable planetary system. Lots of stars have companion stars looked in orbit. Binary star systems are not condusive of planetary formation. Planets, and stars tend to get gravitationally shot out of the system.
A big percentage of stars in galaxies are also in Clusters. A hostile and unlikely place for stable planetary systems. The Nebula in Orion is host to countless Brown Dwarfs, and Gas Giants wondering thoughout them, long detached from there parent star.
Its not as easy as Carl Sagans Formula.
I beleive intelligent life is out there, no doubt about that, but I dont think that its plentifull enough that another civilazation would ignore the discovery of another civilization on another planet.
You also have to think of things like Planet Killers. No doubt that there is intelligent life, growing and evolving out there right this minute. One thing to think of though is how many of those civilazations end prematurely. All it would take to end the existance of us Humans in a short amount of time is a relatively small chunk of rock. Consider how many civilaztaions will get wiped out by such before they can have the technology for space travel.
Space Travel.
Space Travel alone is a whole other aspect to think of. I will remain open minded as to if intelligent life has visited us, I beleive there is a good possbility it has. I believe the ones that might of visited earth live relatively near by. A close star.
Space, time and mass do some very interesting things when you start talking about the speeds that would have to be attained to travel from star to star. You have time dilation, increased mass (mathmatically its supposed to be infinite at the speed of light), and volume issues.
Consider this....You have a space ship that can go the speed of light. You cant just hop in it crank her up and go the speed of light. Nor can you just all of a sudden stop. At least not us humans can.
So, just because the galaxy and universe may be teaming with life, that does not mean that it will ever be able to reach us, or know of our existance. Making me believe that if a civilazation knows of any other life out there, IT WILL TAKE INTREST. For its other nieghbors may be out of reach.
I could go on for at least 9 more pages, and go into great detail, but I dont want to bore everyone to death with my endless jibber jabber. Space, and the physics behind it are one of my specialties.
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