DAVID: Cosmology: milky way size is enormous (Introduction)

by David Turell , Wednesday, June 26, 2019, 15:13 (1978 days ago) @ dhw

DAVID: The entire universe is viewed as fine tuned for life everywhere.
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dhw:The argument as I understand it is that if the universal laws of nature were not as they are, matter would be different, and therefore life as we know it could not exist. You might just as well say that if there wasn’t a universe, there would be no life. It’s a non-argument. At the same time we are told that if our sun were any different and our relationship to the sun were any different, there would be no life. This argues for fine-tuning of our galaxy, but not for fine tuning of billions of other galaxies extant and extinct. We do not know if there is life outside our own galaxy, or if there was life on galaxies that have disappeared. If you tell us that OUR galaxy is fine-tuned for life, it seems to me you have a case. If you tell us that every other galaxy is fine-tuned for life, you have no case until you can prove that there is life on other galaxies. In which case, it is absurd to say that the whole universe is fine-tuned for life.

DAVID: If the universal laws were different, that might be no matter at all. Our galaxy formed within the special parameters that made the universe, and seems to be a very special galaxy.

dhw: Yes indeed. Some people say it is fine tuned for life, unlike other galaxies. That is why it is absurd to claim that the whole universe is fine-tuned for life.

DAVID: There are many types of galaxies all appearing under the same rules. But all galaxies are under the same rules and diverse as they are individually. You are correct in that some special additional fine tuning applies to our galaxy and our Earth, all allowed under the general fine tuned rules of formation of our universe.

dhw: In other words, all galaxies are galaxies, but they are all different. And we cannot say all galaxies (i.e. the whole universe) are fine tuned for life. We can only say that of our own galaxy.

Our galaxy seems very special, but the current scientific opinion among cosmologists is that our universe is at its basis fine-tuned for life to appear somewhere.