Can the Earth be the only place in the Universe that harbors life? Most astronomers don't believe this is true. Certain statistics in the Universe provide evidence that living beings may be common place through out the universe, on planets of other stars besides the sun. In this paper I plan to discuss the various viewpoints of those that believe that extraterrestrials exist and have even been visiting Earth, and the viewpoints of skpetics that believe that aliens don't exist and have not been visiting Earth.
To get into the topic we must first start at the base of the subject. First the question must be dealt with of life being only indigenous to planet Earth. One of the most basic materials that are essential to form life are basic carbon compounds. These carbon compounds are very abundant throughout the Universe. Carbon compounds exist not only on planets but on comets and free floating asteroids and gas clouds in space. Although, even with the abundance of all these compunds in the Universe the chances of these compounds forming into living beings aren't so great, however it is true that the odds of carbon forming into life sustaining compounds is greatly increased with an increase in time. The Universe works on a basis backward to the human way of thinking. The Universe becomes more orderly with time while we would tend to think that time breaks down structures. This means to us that the chances of life evolving on any part of the Universe increases as time moves forward.
Another factor that is necessary for life evolving is a Star's size. Our Sun is a very ordinary star in terms of it size and temperature. Statistics show that there are billions of stars like the sun in our galaxy alone. ( Henbest & Couper, 1989, paragraph 5 ) Life evolving in one of these star systems may have developed in the same way humans have. Philosophers have argued for centures about how to define life. " If we study living things on the Earth, we find that there are some very basic characteristics that will guide us when we consider life elsewhere in the Universe." ( Henbest & Couper, 1989, paragraph 7 ) Life on Earth shows immense diversity. From organisms such as sea slugs to the human being. All life on Earth are made up of the same basic units, cells. Each cell is built up from chains of carbon, the most important element to our existance.
Within our own solar system only 1 out of 9 planets defines as having life as we know it. According to some scientists Mars our sister planet may have started to harbor life early in its evolution but some catastrophic event caused Mars to become the barren frozen wasteland it appears to be today. for our solar system alone 2 out of 9 planets that have or may have had life aren't very bad odds for extraterrestrial life throughout the Universe.
Most skeptics of extraterrestrial life or at least of intelligent extraterrestrial life existing are those...