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I want to share with you something Neil deGrace Tyson said a short time ago during a Reddit AMA. It kinda reassures me that perhaps, after all, we will be able to recognize alien life forms when we encounter them.
Question
Life, as we know it on earth, is cell based, DNA, and so on. If we did find alien life, are we sure we would recognize it? What if alien life is similar to iron, but our tests couldn't even detect some other unearthly element that makes it living. I guess my question is, since earth life is so unique and specific to us, how do we expect to recognize"life" so unique and specific to another world? Could we have seen life on a planet millions of light years away, but not realized it because the details of photography are limited?
Answer(NDTyson)
Excellent question. We think life is alive and a slap of iron is not because, among a few other reasons, we have metabolism. We consume energy in the service of our existence. If we find any other entity that does this too, it would make a good candidate for life. Consider also that you reference and"unearthly" element. That is not likely at all because the periodic table of elements is full. There's no room for any other elements to be discovered in the natural universe. And using spectroscopy, we confirm that these very same elements are found in stars across the universe itself. Not only that, the four most common chemically active ingredients in the universe(H, He, O, C, N) are the SAME four most abundant ingredients in life on Earth. So our bias in searching for"life as we know it" is not entirely close-minded.-NDTyson
From a recent Reddit AMA:
I am Neil degrasse Tyson, your personal Astrophysicist. • r/IAmA
Question
Life, as we know it on earth, is cell based, DNA, and so on. If we did find alien life, are we sure we would recognize it? What if alien life is similar to iron, but our tests couldn't even detect some other unearthly element that makes it living. I guess my question is, since earth life is so unique and specific to us, how do we expect to recognize"life" so unique and specific to another world? Could we have seen life on a planet millions of light years away, but not realized it because the details of photography are limited?
Answer(NDTyson)
Excellent question. We think life is alive and a slap of iron is not because, among a few other reasons, we have metabolism. We consume energy in the service of our existence. If we find any other entity that does this too, it would make a good candidate for life. Consider also that you reference and"unearthly" element. That is not likely at all because the periodic table of elements is full. There's no room for any other elements to be discovered in the natural universe. And using spectroscopy, we confirm that these very same elements are found in stars across the universe itself. Not only that, the four most common chemically active ingredients in the universe(H, He, O, C, N) are the SAME four most abundant ingredients in life on Earth. So our bias in searching for"life as we know it" is not entirely close-minded.-NDTyson
From a recent Reddit AMA:
I am Neil degrasse Tyson, your personal Astrophysicist. • r/IAmA