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20

Earth's radius is about 6400 kilometres. That's 6400000 metres. Let's say that you have a mound 20 metres high, burying an older settlement. Your new "radius" is now 6400020 metres. Let's say that $g = 9.8\ \rm m/s^2$ at 6400, your new gravity will be $g = 9.799939\ \rm m/s^2$. Clearly, this is hardly "lower level of gravity". To make this even less ...


5

To address your original concern, no, the fact that there are buildings underground does NOT mean that the surface of the earth is higher than in the past. What is actually happening is that these buildings are subsiding into the ground. How? Believe it or not, earthworms. Worms were once constantly tunneling through the soil underneath ancient buildings, ...


4

We know the density of the core from seismology. We also know the density of pure iron at given pressure (P) and temperature (T). From these two, people have long noticed that there is a discrepancy: the actual core is lighter than a theoretical core made of pure iron. This is known as the Core Density Deficit (CDD). To explain this CDD, we need to add light ...


3

On a quick approach: Magnetism. The copper itself have a weak magnetism, so a copper core will not create a magnetosphere. Chek here or here. Gravity. The Iron density is 7.874 g/cm³ and the nickel density is 8.908 g/cm³. Copper density is 8.96 g/cm³. So with those density data, the core will be heavier. (The actual core is supposed to have a 9.9-12 g/cm³ ...


3

I've already commented on this before here. This will not work regardless of whether this is iron or lead or anything else. The fact that it was published in Nature does not mean it is true, always remember that. A 108 kg ball of iron would have about 30 metres in diameter, which is not a lot, compared to Earth scales. Here is why it will not work: We ...


3

Because there wasn't enough oxygen to oxidise all of it. There is only so much oxygen on Earth. Most of it went to oxidise the elements that have higher affinities to oxygen: silicon, magnesium, calcium, aluminium, etc. Iron and nickel have lesser affinity to oxygen, so you start by oxidising some of it, until there is no oxygen left. But there is still ...


3

The whole mass of the Earth, mantle, crust, atmosphere and sea, contributes to the Earth's gravitational field, not just the core. Unless you want to split hairs, the Earth's gravity is the same now as it always was. In case you do want to split hairs, the Earth collects a substantial amount of space dust, meteorites and cosmic debris every year, but no one ...


2

The Earth's core is both solid and liquid. The outer core is molten and produces currents of molten nickel/iron which generate the Earth's magnetic field in a dynamo effect, while the inner core is solid. The reason the inner core is solid is that it is under tremendous pressure, more so than the outer core. Scientists know this from the analysis of seismic ...


2

The earth produces 20TW[1] of thermal energy from radioactive decay in the mantle. This is the amount of warmth that the earth generates, so it should give us a ballpark idea of how much heat we would need to remove from the earth in order to make an impact on the earth's internal temperature. To summarize the heating situation under earth's crust, the ...


2

When the Earth was newly formed by collisions with asteroids, comets, planetesimals and other debris of the early solar system 4.6 billion years ago, the planet was incandescent and the mantle hotter and more fluid than it is today. Just as you have heard, the heavy metals sank toward the centre. And just as you say, there is a tiny place at the very centre ...


2

No, simply because we cannot access it and the methods for understanding it are essentially indirect geochemical and geophysical measurements (mostly experimental petrology and wave propagation experiments). We only talk about models, so far. So much so anything deeper than the crust - to be more precise, anything but upper continental crust is either ...


1

This is an interesting question that is maybe a little misguided. Instead of answering your question directly I'd like to draw your attention to some things that might get you to rethink your reasoning. It turns out that what you're thinking of as the lower mantle (an assemblage of solid phases: mainly bridgmanite + ferropericlase + some other stuff) might ...


1

Because the early earth and the current surface of the earth are very different conditions. Any oxidized iron present on the forming earth would have quickly ceased to be oxidized as the planet became molten, Once heated the oxygen would have quickly been stripped away by elements with higher affinity. Silicon for instance has a much higher affinity for ...


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