E.T. Exists!!!

And yet, it happened. Life can be proven to exist on at least one planet, Earth. From there, we can conclude that all of the variables necessary for life to exist are set within our universe, because if they weren't then we wouldn't be having this debate. The possibility of another universe containing the necessary variables is irrelevant to the possibility of life existing within this universe. Whether or not our universe exists independently or as part of a larger multiverse space only brings in the question of the universality of set variables. So what are the variables that are necessary for life to exist? First, we must realize that the physical laws that govern events in this universe are universal in nature, or basically, they apply everywhere in the universe and that not even a galaxy at the edge of the observable bubble plays by a different set of rules [1]. With that in mind, we can confidently assume that another planet, in the right conditions, would create a proper environment for life to originate. Assuming, of course, that the way it is theorized to have happened on Earth would be repeated. So what are the "right conditions" for life to originate? While we are obviously ignorant of possible life that don't have the same requirements as our own, our current definition of "life" only applies to life that would exist similarly to Earth-Life, so this narrows our conditions to only those that Earth-Life requires to exist. These conditions for planets are: 1. They're a comfortable distance away from a star similar to our sun. That is, they're far enough away to be out of the heavy heat and radiation zone, but not so far that they're extremely cold. This just-right distance is called the "habitable zone." 2. They're made of rock. Jupiter, Saturn, and Uranus in our solar system are made of gases, so we don't expect life to be able to survive there. 3. They're big enough to have a molten core. Earth's core gives us a source of geothermal energy, it allows cycling of raw materials, and it sets up a magnetic field around the planet that protects us from radiation. Mars probably had a hot liquid core at one time, but because it's a smaller planet its heat dissipated more quickly. 4. They are good candidates for having a protective atmosphere. The atmosphere holds carbon dioxide and other gases that keep the planet warm and protect its surface from radiation. Those are just for planets and only for planets that would follow a similar existence to Earth. A moon could have all of the necessary conditions for life to exist, but allow them in a different way, such as Europa [2]. Even a rogue planet, a planet detached from it's mother star, could possess the proper requirements [3]. The estimation for habitable planets has been reported a number of times, each within the range of a few billion to tens of billions [4]. For the sake of this debate, I will use the lowest reported value of 2 billion for my final point in this round. The amino acids that are necessary for building DNA and RNA has been created in the Miller/Urey experiment, Juan Oro's testing of Hydrogen cyanide and ammonia, and found within meteorites that have fallen to Earth [5]. By combining all of these factors, we can see that even if there was a 1 in a million chance of life originating on a properly conditioned place, it would still occur two thousand times in just our galaxy alone. This, of course, only addresses the chance of microbial life existing. Microbial life, while still extraterrestrial life, is not intelligent life, so this argument doesn't directly address Con's. But this does: The age of the Universe is estimated to be around 13.7 billion years old [6], The first confirmed signs of life existed 3.5 billion years ago [7]. It took a minimum of 3.5 billion years for Earth to possess it's first intelligent life. Let's cut the amount of habitable planets that are likely to have life down by a factor of 100 for a sake of random events happening that would prevent life from advancing too far, so that leaves just 20. There has been 4 (rounded up from 3.9) 3.5 Billion year time scales since the big bang, let's forget the first one since that is likely to be too hostile for something as fragile as life. Now we are left with three time scales, which we then multiply by the 20 that do likely to have at least microbial life, and we get 60. That's 60 different places in the galaxy where intelligent life, at least as advanced as us, are likely to exist. I would then multiply that by the number of galaxies in our universe, but that doesn't seem necessary. Sources: [1] http://www.amnh.org... [2] http://www.space.com... [3] http://www.space.com... [4] http://space.about.com... [5] http://people.chem.duke.edu... [6] http://en.wikipedia.org... [7]http://en.wikipedia.org...