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Membership
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The Atom (New Rules and New Roads)
Our Universe expanded into existence some 14 billion years ago, creating only the lightest elements, hydrogen and helium. The greater and greater clumping together of matter under the force of gravity led to the creation of stars. Some of these stars exploded, sending the heavier elements, that had been created by nuclear fusion in their cores, into space. This nuclear waste, and interstellar gas and dust, again clumping together, eventually formed our solar system, including the Earth. The iron in our bodies, for example, was formed in the cores of stars. If we are to survive as a species, we must leave the Earth. Our Sun will expand and incinerate our planet in about four billion years. Climatic change will make our planet can uninhabitable in about half a billion years (Carrington, 2000). But within 100 million years, there will not be enough carbon dioxide left in the atmosphere for plants to do photosynthesis (Dawson, 2000). With advanced telescopes, we detect daily, collisions between massive dense objects, which release enormous amounts of radiation. The light from a burst in January 2000 was equal to the radiance of 100 million billion stars. If one of these Gamma-Ray Bursts were to occur in our Galaxy, all land-dwelling life in it would be destroyed (Annis, 1999). It is estimated that thousands of advanced civilizations exist in our Galaxy. Gribbins (1991) suggests that there are 400 thousand technological civilizations in our Galaxy. Most of them are tens of thousands of years ahead of us in their scientific and technological development. This is due to the life suppressing nature of Gamma-Ray Bursts (Annis, 1999). Since collisions between objects in space are proportional to the proximity of such objects, most occur in the centers of galaxies. Therefore, centrally located civilizations can start to develop shortly after such bursts. Since the Earth is about 30 thousand light-years from the Galactic center, the development of intelligent live would be delayed by that length of time. More conservative estimates about life in the Galaxy suggest about 400 intelligent civilization. Assuming a uniform distribution of inhabited solar systems, the nearest one would be about 5,000 light years away. It is expected that an advanced civilization could travel among the stars at about 1/10 the speed of light. Therefore, it would take about 50,000 years for aliens to reach the Earth, once their expansion began. If there is such a civilization between our Solar system and the Galactic center, the most likely time of arrival is thus in 45,000 years. However, Annis (1999) estimates that the evolution of intelligent land-dwelling life takes about 200,000 years. Variations in development, etc., could well give differences in the time to reach the space exploration stage that are significant fractions of this time period. For example, our own development could have been retarded by the ideal 45,000 year delay expected. Until more accurate data is available, we have to assume a wide distribution of probable arrival times. Thus, contact with an alien civilization could occur at any time. Given these assumption, the probability of contact is about one chance in 50,000 per year. This is ten times the probability of a meteor impact that could destroy civilization, which is believe to be the most common external threat to life on our planet. Thus, contact with an alien civilization is by far the most likely extra-terrestial source of influence on mankind. The risk of being killed in a crash of a commercial airliner is about ten times less then this probability. Whether a meeting with a more advanced civilization would be as dangerous as being in a crash is difficult to estimate. However, the meeting of civilizations differing by only a few hundred years in technical development on this planet doesn't suggest a secure future for the lesser developed one.
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