Featured Rethinking the Earth's core

We don't know for absolute certainty what the Earth's inner core is made of, but we know that within a reasonable degree of accuracy that it must be composed of mainly Iron and Nickel with about 3-5% of its mass made up of lighter elements. This is based on observations via seismic waves, the known density of the Earth as a whole vs the density of the crust, the relative abundance of elements throughout the solar system, and many other factors. Silicon is believed to make up the bulk of the lighter elements making up the core primarily because it is by far the most abundant element in the Earth's crust capable of staying mixed with iron and nickel. Oxygen is more abundant, but it boils too easily.

 

Maybe read through the Wikipedia article about the Earth's Structure, and follow some of the references out of the article to some of the peer-reviewed journal articles:

https://en.wikipedia.org/wiki/Structure_of_the_Earth#Core

That should help you understand what Drakkith said in his reply, about how science approaches a question like this.

 

I'm not a geologist, so take the following with a grain of salt:

We rely on a combination of different methods from different fields. For example, we can look at the composition of meteorites, which are believed to be representative of the elements making up the rocky planets, and infer from them the composition of the Earth and other planets. We also know enough about stellar nucleosynthesis (creation of different elements inside stars and supernovas) to know that iron and nickel are very abundant compared to heavier elements and should form a substantial fraction of the non-gaseous material available for planetary formation.

Note that the average density of the Earth compared to the Earth's crust places great constraints on what elements could possibly make up the internal structure of the Earth. Since the density of the Earth as a whole is greater than the density of the crust, this means that heavier elements must be making up a substantial amount of the internal structure of the Earth. This fits with our current models of planetary formation in that when proto-planets are still hot and molten, heavier elements tend to sink inwards, which should lead to a core composed mainly of the heavy elements.

So just based off of the composition of meteorites, known reactions from nuclear fusion, the density of the Earth vs the Earth's crust, and some simple physics regarding buoyancy, we can already say that the Earth's internal structure must be composed of something similar to iron and nickel.

But that doesn't guarantee that the core itself is composed of iron and nickel. Further evidence comes from the aforementioned seismic waves. If, say, the mantle was composed mainly of iron and nickel, instead of silicon and oxygen, seismic waves would behave much differently than we observe. We'd also have massive amounts of molten iron and nickel popping out of volcanoes, but we don't see that either.

The details get very, very complicated. Just try reading this paper for example. Or this one. You'll find that unless you've been trained in geology and whatever else may be required, you will have a lot of difficulty understanding the details underlying all of our models. Unfortunately there is no way to teach this in a forum. You'd need to be formally educated (or devote a substantial amount of personal time) to learn it all.

None of the definitions found here of the word 'guess' seem to apply. While there may some guessing involved during the initial formation of a theory or model, the entire process evolves from a guess into a (hopefully) sound model or theory based on months or years of work. I see no reason to consider the end product of this process a "guess".

No, I wouldn't say that at all.

 

If you can quote the parts that you didn't understand, I think we can help you out. There is some great math behind imaging technologies (much of which existed back in the years you refer to), and with some help from us, you can probably start to understand it.

Saying "I don't believe it because I don't understand the math" is not really accepted here. We are happy to help you understand the math, as long as you are willing to put in the effort.

 

Without doubt? You can't. Ever. It's impossible.

If you'd like to know how seismic waves work and how we detect them, you're going to have to spend a lot of time getting into the technical literature. I certainly don't know the details. But the great thing is that you can find a huge amount of information online, and if not there, then you can almost always order a book off of amazon or somewhere else on a topic. For example, this book would seem to be excellent starting point if you're looking into learning more about seismic theory: https://www.amazon.com/Introduction...TF8&qid=1489199657&sr=8-2&keywords=seismology

If you question the material in that book, then you'd need to get into the underlying physics supporting geology and seismic waves, which, unsurprisingly, is extremely complicated.

The initial idea was a hypothesis, but the subsequent development of that idea turned it into a theory. Note that just because a theory exists does not mean it is correct. The Earth's core could very well be made out of some strange type of matter never seen before. We just have little reason to believe so.

Those phrases are found throughout all of science, so if you're basing your trust on science on whether or not it uses those words then you're going to be sorely disappointed everywhere you look. In the end it comes down to whether you trust that scientists generally know what they're doing or not.