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Our solar system is thought to have begun billions of years ago as a protoplanetary disk. Over time, gravity caused this matter to clump together and eventually form planets. There is debate over the process and its duration, with previous studies suggesting several ten million years until the initially dry Earth was formed. Water was delivered at the end of this period.
A new article in Science Advances (open) describes Iron isotope evidence for very rapid accretion and differentiation of the proto-Earth.
Moreover, new planet formation models based on the rapid accretion of pebbles onto asteroidal seeds suggest that Earth's main accretion phase may have been completed within the ~5–million year lifetime of the protoplanetary disk.
The authors find that the ratio of iron isotopes 54Fe to 56Fe in most meteorites differs from the Earth, and deduce that the planet formed rapidly with little material from the outer solar system, where those meteorites originated. The terrestrial iron isotope ratio does match that of a rare class of meteorites known as CI chondrites.
The only epoch in the history of the solar system when the CI-like material is readily available within the terrestrial planet–forming region is during the lifetime of the protoplanetary disk. This period represents the time when the in-falling envelope material of CI composition is channeled through the disk to fuel the growth of the proto-Sun and is estimated to have lasted approximately 4.8 ± 0.3 million years (Ma).
This conclusion has implications for where the Earth's water and oxygen came from:
An initially more reduced proto-Earth relaxes these constraints and only requires that Earth oxidized (i.e., acquired most of its mantle iron budget) by the accretion of CI-like dust. Water is the key ingredient for oxidation, and as such, our results are consistent with the accretion of a component of Earth's water and other volatile elements during the protoplanetary disk's lifetime. This may be achieved via the direct accretion of water adsorbed to dust or reflects the fact that the snowline will be inside of Earth's orbit toward the end of the protoplanetary disk's lifetime, allowing direct accretion of ice during this stage.
Regarding the Moon:
Critically, the rapid timescales proposed here can be reconciled with Earth's mantle 182W isotope composition if the Moon-forming impact occurred at least 40 Ma after the main accretion and differentiation of the proto-Earth.
(Score: 0) by Anonymous Coward on Sunday February 16 2020, @07:31AM (5 children)
"Keep in mind that the present theory is that there wasn't any Earth life, much less children who could record things, during the alleged formation of Earth 4.5 or so billion years ago."
Let me respond to this again. You're kinda missing the point in favor of nit picking at semantics and grammar. Yes, 'science' is a human endeavor invented by humans. However for science to exist, for us to be able to observe and describe the consistency and structure in the universe, the universe must have consistency. The existence of science evidences the existence of God because the fact that the universe allows for science to exist tells us that the universe is not a product of random chance.
If the universe is a product of random chance I would expect the universe to be a random universe with no consistent or predictable laws, properties, or characteristics. But it's not. It's a universe that continues to allow us to predict future events within a consistent tolerance. I throw a ball into the air and it comes back down. I do it again, it comes back down again. At no point in the future will it just randomly disappear instead of coming back down. Past instances of the universe aren't random, neither are present instances, and future instances continue not to be non-random.
In a random universe the production of future instances should not depend on past instances so even if a low entropy set of events did randomly occur over a specific time interval future time intervals should not be affected and should continue being highly random. Yes, if I throw a ball in the air enough times it's possible for me to get three instances in a row that it comes back down by chance. But if the universe is a product of random chance those three instance should not affect future outcomes and I should not be able to reliably predict that throwing the ball in the air a fourth time will result in it coming back down again.
(Score: 0) by Anonymous Coward on Sunday February 16 2020, @07:33AM
Errr ... typo
and future instances continue to be non-random. *
(Score: 1) by khallow on Sunday February 16 2020, @04:04PM (1 child)
So what? That would be the case whatever "God" happens to be: for example, random chance, some intern's computer simulation, and/or sentient omnipotent being with purpose. The anthropic principle is enough. Further, whatever structure the universe has would be considered of significance no matter how much or what that structure happened to be.
What's important here is evidence - observation or whatever that distinguishes between hypotheses. The observation that things are structured doesn't tell us anything since we can't exist otherwise and as of yet, we have yet to observe anything else other than our particular neck of the woods.
(Score: 0) by Anonymous Coward on Thursday February 20 2020, @08:41PM
"The observation that things are structured doesn't tell us anything since we can't exist otherwise"
This is a non-sequitur. Just because we can't exist in the absence of structure doesn't mean the existence of structure doesn't tell us anything.
"we have yet to observe anything else other than our particular neck of the woods."
Imagining other universes exist isn't science.
"Further, whatever structure the universe has would be considered of significance no matter how much or what that structure happened to be."
Which isn't an argument for or against design and misses the argument being made.
(Score: 1) by khallow on Sunday February 16 2020, @04:27PM (1 child)
This isn't about whether processes are sufficiently science-like to count semantically or your grammar. It's about simply not being there to observe the beginning of the universe, the Solar System, or almost the entirety of the creation and evolution of Earth. By necessity, we have to piece this together from the few clues we have now.
And I think you're kinda missing the point by dwelling on semantics and grammar rather than the actual disagreement.
(Score: 0) by Anonymous Coward on Thursday February 20 2020, @08:49PM
"And I think you're kinda missing the point by dwelling on semantics and grammar rather than the actual disagreement."
I was arguing that the existence of science is strong evidence for a designer because if there were no designer I would expect a random universe with no consistency. Your argument was that science is man created and if there is no man there is no science. That's missing the point and making a slight grammatical correction.