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Originally Posted by Bill Thompson
1. It doesn't matter that there are billions of galaxies with billions of stars. The distance between galaxies is so staggering that any civilization in another galaxy would have changed or died during the time it would take to communicate to another galaxy.
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We could listen-in for a while.
Our desire to find a means of communication will be highly strengthened by finding intelligent life. String theory with 10 (or 11 with M-theory) may allow some form of communication in the future, worm holes (possibly, but not likely), particle entanglements which occur instantly across the universe, etc. These are hints of things to come.
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Originally Posted by Bill Thompson
2. Things are not as they appear. And reality is not as hopeful as scientists who are looking for ET suggest. Technology has given us the ability to look for extra-solar planets. But scientists fail to mention that they are focusing their attention on star systems that are not binary. You see, eventhough there are billions of stars in our galaxy, you can take more than 2/3rds of those stars and disgard them in a search for ET because they are binary stars.
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You are being a little generous still. GRB's may have sterlized large regions in the early days. Large stars don't last long. Small stars have problems, too. Of course, that still leaves billions of potential regions for life. 8)
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Originally Posted by Bill Thompson
3. Even if Life is abundant in the Galaxy, plant and animal life is rare.
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Also notice that plant and animal life occurred after a series of unlikely events. And, on top of all this, human life and other intelligent life is even rarer. Even if you take Earth as a model of a planet that exists throughout the galaxy we are still most likely alone.
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Still too early to draw any solid conclusion. Mars may still have living organisms under the surface.
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Originally Posted by Bill Thompson
4. Liquid water is rarer than you might think. Scientists that are hopeful that we are not alone in the galaxy often mention that all is needed is the existance of liquid water. It is a very common mistake that temperature is the only factor in keeping water in a liquid state. This is not true. Liquid water is rare because it requires a combination of temperature and pressure. Liquid water "boils" at room temperature in a vaccume.
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Good point. No doubt there really is a "sweet spot" (habitable zone) for these conditions which varys with star types. Spitzer's discovery of a planet forming within the star's accretion disk should make the subject less dry. :-? (sorry)
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Originally Posted by Bill Thompson
By the way, it is the lack of atmospheric pressure on Mars (1% of that on Earth) that is the reason why liquid water does not exist there today.
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I wonder what the water looks like under the surface. #-o
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Originally Posted by Bill Thompson
5. Geologists think that or sort of Earth/Moon arrangement is important for the existance of the kind of life we have:
http://www.spacedaily.com/news/life-01x1.html. So the question arises, how probable is it that a small, rocky planet could have a planetoid moon of our size. According to the BBC special "The Planets" it is very improbable. Part of the mission of the Apollo project was to determine the origin of our moon. Because of the age and compisition of the rocks on the moon it was eventually determined that the moon was born from a collision of another smaller planet into the Earth. Somehow the Earth survived and the upheaval of debris formed the moon. It is not very likely that our Earth/Moon arrangement is common. |
For advanced forms of life, this appears to be a big issue.
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Originally Posted by Bill Thompson
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Nice links. Sometimes it's just hard to know what we don't know. [hopefully, I am quoting someone intelligent.
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