Rewriting Earth's Creation Story: Hadean epoch a scientific myth

[C C]

http://www.theatlantic.com/science/archi...an/501668/

EXCERPT: [...] Geologists named this epoch the Hadean [...] Only after the so-called Late Heavy Bombardment quieted some 3.9 billion years ago did Earth finally start to morph into the Edenic, cloud-covered, watery world we know. [...] But as it turns out, the Hadean may not have been so hellish. New analysis of Earth and moon rocks suggest that instead of a roiling ball of lava, baby Earth was a world with continents, oceans of water, and maybe even an atmosphere. It might not have been bombarded by asteroids at all, or at least not in the large quantities scientists originally thought. The Hadean might have been downright hospitable, raising questions about how long ago life could have arisen on this planet. [...] “There is absolutely not a single scrap of observational evidence that requires that scenario ever took place. We as a scientific community created an origin myth that has no more intellectual value than 1 Genesis,” Harrison says. “Although we’re very quick to criticize those that operate on faith, that’s exactly what we did....”

[Yazata]

EXCERPT: [...] Geologists named this epoch the Hadean [...] Only after the so-called Late Heavy Bombardment quieted some 3.9 billion years ago did Earth finally start to morph into the Edenic, cloud-covered, watery world we know. [...] But as it turns out, the Hadean may not have been so hellish. New analysis of Earth and moon rocks suggest that instead of a roiling ball of lava, baby Earth was a world with continents, oceans of water, and maybe even an atmosphere.

If the Earth formed from accretion of planetesimals in an early accretion disk, that process would have taken some time. Each of the new additions would have released lots of energy as it collided with the proto-Earth. Each would need to have been squished down into the rest (like modeling clay) by gravity. That would have kept the surface unsettled. Then there's the theory that the mass of the Moon was torn from the body of the Earth by an impact with a Mars sized body. That would have disrupted the Earth's surface for some time afterwards, making it very inhospitable for the origin of life.

It might not have been bombarded by asteroids at all, or at least not in the large quantities scientists originally thought.

The Moon certainly seems to have been. So if asteroids were pocking craters all over the pristine newly formed Moon, why wouldn't they have been doing the same to Earth? Earth is a bigger target.

The Hadean might have been downright hospitable, raising questions about how long ago life could have arisen on this planet. [...] “There is absolutely not a single scrap of observational evidence that requires that scenario ever took place. We as a scientific community created an origin myth that has no more intellectual value than 1 Genesis,” Harrison says. “Although we’re very quick to criticize those that operate on faith, that’s exactly what we did....”

That's shamelessly overstating things. It's probably what caught the attention of the writer from The Atlantic though. I still want to know how these people think their Edenic very early Earth formed all once with conditions like we experience today. I want to know what they have to say about the accretion disk theories and how they explain away the catastrophic impacts. The idea that the Hadean era concept is based entirely on faith is foolishness in my opinion. It isn't based on ancient myth or on religious tradition. It's a hypothesis based on current theory about how the earth originally formed and on actual tangible evidence about conditions in the early solar system. It's as strong as our evidence about the origin of the Moon and the origin of its craters. How did the Lunar 'seas' form if there weren't large flows of fluid rock at one time on the lunar surface? If the Moon was very different in its youth than it is today, then it's reasonable to think that its neighbor right next door might have been different in its earliest period too.

[C C]

Rather than throwing the whole Hadean into this, it should have been better emphasized by these articles that only the Late Heavy Bombardment is being debunked by these geologists (i.e., the very "tail-end" of the Hadean). Some of the remarks of the scientists themselves seem responsible for encouraging a wide generalization of what "Hadean" embraces here, among science writers.

The LHB was actually still controversial even before their research, despite its popularity. If not for the material collected by the Apollo mission, the LHB probably wouldn't have even been conceived; that was both the stimulus and the primary "evidence" for it.

The hellish conditions and immense spike in impacts which the LHB represents (to the point of even positing asteroid collisions being involved) depends itself upon the Hadean period having settled down beforehand. So as to justify the LHB standing out as a remarkable duration compared to the typical range of activity.