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Author | Topic: center of the earth | |||||||||||||||||||||||||||
simple  Inactive Member |
quote:Fine. Sounds reasonable. I thought I had read something about how, pressure alone, if high enough, would have turned gold into liquid. Point noted
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CK Member (Idle past 4158 days) Posts: 3221 Joined: |
quote: Really?
quote: This message has been edited by Charles Knight, 30 January 2005 17:01 AM
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JonF Member (Idle past 199 days) Posts: 6174 Joined: |
Could superpressurized water, with a phase zone of gold, or graphite, as it got closer to the 'diamond', fool the waves, at least our reading of them? No. We would see the boundaries.
Can the waves require, heat assumptions aside, the core to be dense as iron. Are you suggesting something in the waves narrows down the density aspect to the same as iron for sure? Pretty much. It has to have values for several properties that produce the right predictions for wave velocities. See below.
It would have to be how fast the waves pass through the core, I presume. But I have not heard someone come out and say something like this. 'Sound waves travel through the core at xxxx mph, and take xxxx minutes to do so, so, since it is 1500 (or whatever) miles long, the density of the core must be exactly, xxxxx. If you can establish it has to be a certain density, I can just look at material in the right range for cool suspects. Ah, that's because you haven't looked for or looked at any evidence, you are just making it up as you go along. The velocity of of P waves depends on the density, shear modulus, and bulk modulus of the material:
Vp =
(linked from Velocity of P and S-waves...) K is the bulk modulus, µ is the shear modulus, and r is the density. K and µ change under pressure, but not a heck of a lot; they mostly depend on the strength of the atomic bonds that hold the material together. µ is zero for all liquids. r changes under pressure for some materials, but not for others, and can change discontinuously with pressure if the materials structure changes. The velocity of S waves is:
Vs =
(from the same source as above) By studying waves from many sources arriving at many detection stations, we can figure out what the velocity of both types of waves is as a function of depth1, without making any reference to temperature:
(linked from the end of Earthquakes & their Uses {Seismology}) (Notice the sudden changes where it changes from solid to liquid or vice-versa. We would see similar jumps at any sudden change in solid properties, such as a layer of gold changing to a layer of diamond). So, there you go. When you plug the properties of iron into those equations, they produce the observed wave velocities quite nicely (except we have to assume that about 10% of the core is nickel and other contaminants to match the density, which complicates the analysis some, but is justified by other evidence). All you have to do is to show that the properties of any material you want to propose produces the observed wave velocities when plugged into these equations. ----------------------- 1In fact, these waves are used to make "CAT scans" of the Earth; googling "seismic tomography" will turn up some fascinating images, including convection in the mantle and subducting plates. {edited to fix second equation} This message has been edited by JonF, 01-30-2005 17:16 AM
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JonF Member (Idle past 199 days) Posts: 6174 Joined: |
If I get to an assertion phase, I'll let you know As Charles pointed out, you have already:
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simple  Inactive Member |
quote:Yes, in my opinion, if we could fit the evidence we do have in a cooler model of the interior, it would be a better one, if it ends up fitting the evidence better. No we are not. of course there yet!
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CK Member (Idle past 4158 days) Posts: 3221 Joined: |
How can you have a model if you don't make any assumption or supply any evidence?
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CK Member (Idle past 4158 days) Posts: 3221 Joined: |
Can I suggest that when we get to the magic number of 300 posts that unless Cosmos can supply some rational reason for us to carry this mess forward (in the form of a decent OP? that we wrap it up?
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simple  Inactive Member |
quote:I am wondering, just about that at the moment. There is said to be a 'd' zone or area actually, between the outer core and inner-different in composition. " "D" layer: depth of 2,700-2,890 kilometres This layer is 200 to 300 kilometres thick. Although it is often identified as part of the lower mantle, seismic evidence suggests the D" layer might differ chemically from the lower mantle lying above it. Scientists think that the material either dissolved in the core, or was able to sink through the mantle but not into the core because of its density." Page not found - Moorland Private School So it seems there is a boundry for us here! Potentially. quote:Thanks, sounds like it should be doable? By the way, the particular site, and diagram happened to leave out the potential boundary I just 'proposed'. So, apparently we have some stuff (d) that is at the border of the inner and outer core. It can't penetrate the 'diamond', or core (whatever it is made of). Yet, as someone else pointed out, we need to come up with the right specific gravity (density balance). Using just a sample of diamond, and water, this does not match. Gold has very heavy specific gravity, about 19.3. We need to come up with around 5.5, I believe, and the diamond was only around, as I recall about 3.5 or 3.9. Now if we looked at the 19.3/3.9/and water, I think it was 1 -what would we average out to? Would it not be in the ballpark? Anyhow thanks for the wave stuff, it's something to chew on.
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simple  Inactive Member |
quote:People, except you, of course, have been trying to do that.
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CK Member (Idle past 4158 days) Posts: 3221 Joined: |
I'm confused - you told ned that you had not proposed anything but were just putting things "out there"?
Now you are saying people are helping you to refine a model? Which is it? I tend to lurk on scientific threads where my knowledge is limited. However no special expertise is needed to comment on your shifting and changing use of terminology and where you stand. This message has been edited by Charles Knight, 30 January 2005 18:30 AM
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JonF Member (Idle past 199 days) Posts: 6174 Joined: |
There is said to be a 'd' zone or area actually, between the outer core and inner-different in composition. Look again. The "D" layer is between the outer core and the mantle ... and, indeed, the figure I posted shows a change in the trend of the P wave velocity, and perhaps a change in the trend of the S wave velocity (it's hard to tell at that scale), at exactly that point. Don't forget that you have to come up with the correct total mass and moment of inertia for the Earth, also.
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Brad McFall Member (Idle past 5063 days) Posts: 3428 From: Ithaca,NY, USA Joined: |
Bridgman had,
quote:
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AdminJar Inactive Member |
Cosmo, this is your final notice.
Stop right now and provide something in the way of valid evidence that will support your assertions. Your next post MUST include some valid scientific evidence that supports an earth with a diamond core surrounded by gold. No excuses. No other replies. No discussion. Provide the evidence. New Members should start HERE to get an understanding of what makes great posts.
Comments on moderation procedures (or wish to respond to admin messages)? - Go to:
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JonF Member (Idle past 199 days) Posts: 6174 Joined: |
Cosmo, I'm pretty convinced you aren't really interested in making a model; I bet you just want to be a gadfly without considering the possibility that your ideas are wrong. In case I'm wrong, look at GS 388 Lab 5: Density and Radial density distribution via the Adams-Williamson equation. That's lab material for EAS 388, Geophysics and Geotectonics. This course and lab covers exactly what you claim to be attempting to do. The handouts contain all the equations and data you will need. You don't have to accept all their reasoning why the density should vary in a particular way . Let us know when you've finished the calculations.
{Changed subtitle by edit} This message has been edited by JonF, 02-01-2005 07:41 AM
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JonF Member (Idle past 199 days) Posts: 6174 Joined: |
Jeez, I love the Internet.
Alan L. Jones has written two Computer Programs for visualizing all sorts of earthquake stuff, including internal wave propagation. One updates its database of earthquakes over the Internet and will notify you of earthquakes within minutes if you wish. The one that shows internal propagation doesn't have as up-to-date a database, but the earthquake that caused the recent tsunami has been added to the database. Who woulda thunk it. Both free. {changed subtitle in edit} This message has been edited by JonF, 02-01-2005 08:01 AM
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