Paul Davies Quotes About Earth
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We know that within the solar system is very unlikely there will be anything more advanced than microbial life, but if we think outside the solar system and then, the distances are, of course, immense, then there could be Earth-like planets with more advanced form of life.
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I should say we know that there are many, many other Earths out there. We're almost certain that there will be upwards of a billion Earth-like planets in our galaxy alone, so there is no lack of real estate where life might happen, but what we don't know is how likely it is given the real estate, given a wonderful pristine planet like Earth how likely is it that life will pop up inhabited? We don't know the answer to that.
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If we're thinking about old civilizations, those that formed a long time ago and there were stars and planets around long before Earth even existed, then these are going to be towards the center of the galaxy. That is the place to look if you think there are ancient civilizations that have made beacons or some other way of attracting our attention.
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The secret of our success on planet Earth is space. Lots of it. Our solar system is a tiny island of activity in an ocean of emptiness.
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Astronauts have been stuck in low-Earth orbit, boldly going nowhere. American attempts to kick-start a new phase of lunar exploration have stalled amid the realisation that NASA's budget is too small for the job.
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Clearly, some creative thinking is badly needed if humans are to have a future beyond Earth. Returning to the Moon may be worthy and attainable, but it fails to capture the public's imagination. What does get people excited is the prospect of a mission to Mars.
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In time, [a Martian] colony would grow to the point of being self- sustaining. When this stage was reached, humanity would have a precious insurance policy against catastrophe at home. During the next millennium there is a significant chance that civilization on Earth will be destroyed by an asteroid, a killer plague or a global war. A Martian colony could keep the flame of civilization and culture alive until Earth could be reverse-colonized from Mars.
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Most life on Earth is microbes. we've only just scratched the surface of the microbial realm. Probably less than .1% of microbes have been classified let alone cultured or had their genes sequenced, so really that microbial realm is a mystery.
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If we do discover more than one type of life on Earth, we can be fairly certain that the universe is teeming with it, for it would be inconceivable that life started twice here but never on all the other earth-like planets.
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So how can we test the idea that the transition from nonlife to life is simple enough to happen repeatedly? The most obvious and straightforward way is to search for a second form of life on Earth. No planet is more Earth-like than Earth itself, so if the path to life is easy, then life should have started up many times over right here.
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An argument often given for why Earth couldn't host another form of life is that once the life we know became established, it would have eliminated any competition through natural selection. But if another form of life were confined to its own niche, there would be little direct competition with regular life.
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In the 1990s I began to study the prospects that life could spread from Mars to Earth or maybe Earth to Mars and that maybe life began on Mars and came to Earth, and that idea seemed to have a lot of traction and is now accepted as very plausible.
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Searching for alternative life on Earth might seem misconceived, because there is excellent evidence that every kind of life so far studied evolved from a common ancestor that lived billions of years ago. Yet most of the life that exists on Earth has never been properly classified.
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When I was a student almost nobody thought there was any life beyond Earth. Today it's fashionable to say that there is life all over the place, that the universe is teeming with it, but the scientific facts on the ground haven't really changed.
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The problem here is that a civilization that is 1,000 light years away doesn't know we exist. They don't know that we have radio telescopes here on Earth because they see Earth as it was 1,000 years ago. Nothing can travel faster than light, so however good their instruments they can't see in affect the future. So there is no particular reason they should be sending us messages at this time.
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The universe contains vastly more order than Earth-life could ever demand. All those distant galaxies, irrelevant for our existence, seem as equally well ordered as our own.
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No planet is more earth-like than Earth itself, so if life really does pop up readily in earth-like conditions, then surely it should have arisen many times right here on our home planet? And how do we know it didn't? The truth is, nobody has looked.
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What we want is another sample of life, which is not on our tree of life at all. All life that we've studied so far on Earth belongs to the same tree. We share genes with mushrooms and oak trees and fish and bacteria that live in volcanic vents and so on that it's all the same life descended from a common origin. What we want is a second tree of life. We want alien life, alien not necessarily in the sense of having come from space, but alien in the sense of belonging to a different tree altogether. That is what we're looking for, "life 2.0."
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