Ask a geologist thread

[hackenslash]

Kinda supports my point, really. Any free oxygen at the start would combine with other elements more readily than with H (just mixing the two gases won't work as there's a thermodynamic energy barrier to overcome).

A barrier easily overcome by the simple expedient of giving it a nudge with, say, a lit match or, for example, the impact of a small bolide, of which there were many at the time.

Anyhoo, I have a pretty good geology question:

Have you seen the 'expanding Earth' thread 'over there', and what do you think?

[Svartalf]

I'll start with a simple one, before Gawd gets to it:

How did the Earth come to be as it is now? How was it formed?

The creationists have it so easy - just turn the Genesis 1 and no further brain exercise is required.

Ok executive summary of Earth history:
Earth accreted from the condensation of a rotating solar nebular, simultaneously with the other planets, about 4.5 billion years ago. Initially very hot with frequent volcanism and impacts from space and in the final stages of accretion. After a few hundred million years the temperature dropped to the point where liquid oceans formed - a Goldilocks planet rife for the appearance of life. Life probably started before 3.5 billion years ago (controversial) and by 2.5 - 2 billion years ago (plus or minus quit a bit) had changed the Earth to an oxygen bearing planet rather like today. Animals emerged around 600 million years ago and have infested the Earth ever since.

Ignore this if it's been answered in the course of the thread (I am reading it) ... but do geologists have any idea why we cot so much iron an silicon when we have gas giants made mostly of hydrogen, helium, and carbon compounds?

[hackenslash]

Ignore this if it's been answered in the course of the thread (I am reading it) ... but do geologists have any idea why we cot so much iron an silicon when we have gas giants made mostly of hydrogen, helium, and carbon compounds?

In the case of iron, this is fairly straightforward, and it's to do with the stability of the nucleus and the lowest energy configuration.

There are two forces at play here, namely the strong nuclear force and the electromagnetic force. The strong nuclear force is, as the moniker suggests, strong, but its range is very short. The electromagnetic force is weaker, but operates over a longer range. Bear in mind that, in the electromagnetic force, like charged particles repel.

When there is a relatively small number of protons and neutrons (nucleons) in a nucleus, adding nucleons is energetically favourable, because the electromagnetic force between the nucleons on one side of the nucleus and the other are overcome by the strong force. As the nucleus gets larger, the balance between the two forces shifts, and the electromagnetic repulsion of like charges overcomes the attraction of the strong nuclear force. Beyond this point, removing nucleons becomes energetically favourable. Iron is pretty much at the centre point, which means that the attraction of the strong nuclear force and the repulsion of the electromagnetic force are reasonable equal.

The above is very loosely explained, but reasonably robust.

As for silicon, the answer is simply that it formed, along with oxygen, the majority of the protoplanetary disk from which the solar system formed. The reason for that is that silicon burning is the final stage of high-mass stars (>11 times the mass of the sun) at the end of their main sequence, and after the triple-alpha process responsible for carbon production.

[Faithfree]

Kinda supports my point, really. Any free oxygen at the start would combine with other elements more readily than with H (just mixing the two gases won't work as there's a thermodynamic energy barrier to overcome).

A barrier easily overcome by the simple expedient of giving it a nudge with, say, a lit match or, for example, the impact of a small bolide, of which there were many at the time.

Anyhoo, I have a pretty good geology question:

Have you seen the 'expanding Earth' thread 'over there', and what do you think?

Just went over for a look. Wow - 274 pages - something is certainly expanding, but I don't think it's the Earth! After randomly browsing back through the thread I'm coming to the opinion that Expanding Earth enthusiasts have a lot in common with conspiracy theorists. Ignore 99% of the data with claims it's irrelevant, wrong or deliberate lies, while focusing on the 1% of the data that seem to support your contention. Then make lots of other stuff up.

[Thinking Aloud]

I actually replied to that when it was in its infancy, but quickly realised there was no point whatsoever trying to discuss anything with people who's argument rested solely on "these computer generated graphics of an expanding earth look convincing, and I've never seen standard plate-tectonic graphics that look so cool".

[Gawdzilla Sama]

So, what do they think is making Earth expand, do they think it's hollow like a balloon, and if not, where is the matter coming from to fill it in as it expands?

Or do they think about such things at all?

[Svartalf]

Don't you know we're at the other end of a wormhole and are getting matter pumped in from a black hole?

[FBM]

Probably eating too many Big Macs and super-sized freedom fries.

[Faithfree]

So, what do they think is making Earth expand, do they think it's hollow like a balloon, and if not, where is the matter coming from to fill it in as it expands?

It varies, depending on the expander. Neal Adams, the cartoonist whose video animation sparked the thread off, seems to believe new matter is actually being created at the centre of the Earth by some sort of mystical nuclear process, so the earth is not only expanding, but gaining mass as well.

I like potholer54's humorous take on the whole farcical affair:

[youtube]http://www.youtube.com/watch?v=epwg6Od4 ... re=related[/youtube]

[Gawdzilla Sama]

"So where did all this mass come from? I don't know." So fucking stop that shit then!

[FBM]

The earth is so too expanding. I know it because every year things get further away, fuzzier and harder to see. The only way I can keep up with the expanding earth is to update my eyeglass prescription from time to time. So there. QED.

[Gawdzilla Sama]

The earth is so too expanding. I know it because every year things get further away, fuzzier and harder to see. The only way I can keep up with the expanding earth is to update my eyeglass prescription from time to time. So there. QED.

If the Earth was expanding at the same rate I am we'd be on Jupiter right now.

[mistermack]

If the Earth was expanding at the rate that they claim, there is NO WAY that we would have oceans, or an atmosphere now. The pull of gravity years ago would have been much too small to keep gases from floating off into space. And I'm pretty sure that that would include water vapour.

So unless there was some way that the Earth has been losing density to expand, then it's impossible.
The core would have to be something pretty odd for that to happen.

[FBM]

If the Earth was expanding at the rate that they claim, there is NO WAY that we would have oceans, or an atmosphere now. The pull of gravity years ago would have been much too small to keep gases from floating off into space. And I'm pretty sure that that would include water vapour.

So unless there was some way that the Earth has been losing density to expand, then it's impossible.
The core would have to be something pretty odd for that to happen.

Eh? The tinfoil hat crowd's idea is that the earth has been gaining mass, causing it to expand, thus increasing gravity, which would trap the atmosphere even more strongly, as well as making it harder for me to crawl out of bed in the a.m., which seems to fit, now that I think of it.

[mistermack]

Kinda supports my point, really. Any free oxygen at the start would combine with other elements more readily than with H (just mixing the two gases won't work as there's a thermodynamic energy barrier to overcome).

A barrier easily overcome by the simple expedient of giving it a nudge with, say, a lit match or, for example, the impact of a small bolide, of which there were many at the time.

Anyhoo, I have a pretty good geology question:

Have you seen the 'expanding Earth' thread 'over there', and what do you think?

Would a spark be enough to ignite Hydrogen and Oxygen at super-cold temperatures in space though?
I don't know, I'm just wondering. I think it would have to be a very dense mix. But I'm sure that any free hydrogen and oxygen on the early Earth would find temperatures to encourage combustion.

Anyway, I was really wondering where "over there" is.