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Thread: (Layman Science Series) Week 2 - Why is the center of the earth so hot?

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    Default (Layman Science Series) Week 2 - Why is the center of the earth so hot?

    Intro
    I am trying to post a science/physics question of varying difficulty each week for this year.

    The Rules are:
    Answers must be complete, and each statement must be sound/logical.
    The better the answer, then the more points awarded. Answers can always be updated at anytime as
    we learn something new everyday.
    The greater the difficulty, the greater the points. I will give an answer at end of week. Repeating my
    answer awards no points, you will have to come with a better or alternate answer.

    Question
    Why is the center of the earth so hot? Assume that the earth started out as a rogue planet from deep space that got caught in the sun's gravity

    Difficulty
    A-Level Physics
    A-Level Geology

    Site share of the week
    Real Engineering - YouTube
    https://www.youtube.com/channel/UCR1...6UEA_zQ81kwXfg
    Selfishness is the gateway to Self Destruction
    Lack of "Wokeness" is to be reincarnated as a tapeworm, whereas more awareness give rise to higher level feelings and relations with others

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    Interesting concept. And not thrown outward from the BBT? Hmm....

    Alright. Let's say our sun is fairly new and Earth got caught in the gravitational pull while being thrown nearby. This would then say that Earth was a planetoid of sorts that had an existing core. The rotation balancing act by the core versus the planet's rotation - with just the right distance from the sun - then would have allowed for life to form. If we consider that some bacteria may be found on other planets, it's not outlandish to think that we would have then evolved from tardigrades. I just wish we had retained the "Duncan MacLeod" ability.

    All in theory. Not an evolutionist. For discussion purposes.

    Hopefully not too much info, but enough to get persons thinking.
    Knowing the solution doesn't mean knowing the method. Yet answering correctly and regurgitation are considered "learning" and "knowledge".

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    Alright. Let's say our sun is fairly new and Earth got caught in the gravitational pull while being thrown nearby. This would then say that Earth was a planetoid of sorts that had an existing core. The rotation balancing act by the core versus the planet's rotation - with just the right distance from the sun - then would have allowed for life to form. If we consider that some bacteria may be found on other planets, it's not outlandish to think that we would have then evolved from tardigrades. I just wish we had retained the "Duncan MacLeod" ability.
    Lol
    However, It probable would not be nice traveling tru deep space without sufficient food .

    Actual the question is still in keeping with the Big Bang Theory
    https://en.wikipedia.org/wiki/Rogue_planet
    A rogue planet (also termed a free-floating (FFP), interstellar, nomad, orphan, sunless, starless, unbound or wandering planet) is an interstellar object of planetary-mass, therefore smaller than fusors (stars and brown dwarfs) and without a host planetary system. Such objects have been ejected from the planetary system in which they formed or have never been gravitationally bound to any star or brown dwarf.[1][2][3] The Milky Way alone may have billions to trillions of rogue planets, a range the upcoming Nancy Grace Roman Space Telescope will likely be able to narrow down.[4][5]
    As far as we know Earth could be, but I am not saying it is. We just don't know. I think the common theory is that it is not. However the Earth does not fully match the typical composition and size at this orbit. We just don't know. However the point here is to theorize in a logical step by step approach.

    A planet can leave a solar system if solar "gravity" or "planetary angular moment" changes to some degree.

    There are high energy comets, and asteroids which can knock a planet. Even a comet passing near to a planet can transfer its kinetic energy to a planet, called orbital sling shot. I think the theory was awarded a Nobel Prize, and it is a technique NASA use to get more kinetic energy to launch crafts. If you maths it out correctly, a craft can get slingshot at a higher velocity as it passes a gravitational body moving in it orbit. As the crafts get near, the body pulls the craft (gravitationally and along its own orbit), but the craft should have enough velocity to curve and not fall to the body.

    Stars loosing energy/mass change their gravitation pull. Explosions create a push outwards to destabilize orbits (probable obliterate planets to molten pieces. It depends). This may cause rouge planets (or rouge molten asteroids which then sphere up, radiates and cools).

    Finally, a rogue planet or object that is moving in (almost) a straight line will get caught in an orbit (spiral to a stable orbit) of a star (or other big body) if its Newtonian velocity causes its increasing centripetal force to match the gravitational force of the solar system it enters. Otherwise it will just curve and escape, or spiral towards the star (In Einsteinian terms, the space time bending becomes circular at that speed when it enters the solar system.)

    Even though earth's orbit is stable right now, the galaxy is dynamic at greater time scales.

    Assuming "Earth was a rogue planet" is just to get a starting point that "it would be cold" since it would have radiated its heat. Thus the question now is "why is the core hot?" using just A-Level Physics and Geology
    Selfishness is the gateway to Self Destruction
    Lack of "Wokeness" is to be reincarnated as a tapeworm, whereas more awareness give rise to higher level feelings and relations with others

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    https://www.discovermagazine.com/pla...of-earths-core

    By duplicating the extreme heat and pressure at the Earth’s core, a European research team has determined that the temperature of the center of our planet is close to 11,000 degrees Fahrenheit — nearly 2,000 degrees hotter than previously thought.

    Earth’s solid inner core is surrounded by a fluid outer core, with the boundary between the two expected to be the temperature of the melting point of highly pressurized iron — the primary ingredient of both layers. Researchers placed a speck of iron between two small conical diamonds and applied laser-beam heat and 200 gigapascals of pressure. As the iron changed from solid to molten, they measured the temperature by noting a change in how X-rays were diffracted — a faster, more precise method than the simple visual techniques used in older experiments.

    Knowing Earth’s core temperature is key to understanding the planet’s internal processes, particularly its magnetic field and geothermal activity, explains research team leader Simone Anzellini of the French Alternative Energies and Atomic Energy Commission.
    Selfishness is the gateway to Self Destruction
    Lack of "Wokeness" is to be reincarnated as a tapeworm, whereas more awareness give rise to higher level feelings and relations with others

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    Still waiting on more details on this. Been a bit on the sick side - flu - and recovering. Not as active as a result especially when you still have work to do.
    Knowing the solution doesn't mean knowing the method. Yet answering correctly and regurgitation are considered "learning" and "knowledge".

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    Quote Originally Posted by khat17 View Post
    Still waiting on more details on this. Been a bit on the sick side - flu - and recovering. Not as active as a result especially when you still have work to do.
    Apologies, I have been gone for a while. Everyone's time is precious. I assume that by now you have made a full recovery.


    To explain this question, I think for "understanding sake" I should explain the difference with air, water, and earth, and why physical processes can differ among them, and thus why, the same explanation can't be used as the main cause for each heat flow.

    Air is a mixture of gases. It expands easer relative to the others and mixes easier as well.
    Mixing is done by diffusion (Brownian Motion) and convection currents.
    There is still some degree of separation of gas, at a far away perspective, a sort of equilibrium of concentrations due to density of molecules and gravity separation. For example, a methane layer is formed. Methane rises because of its low density. It also gets dispersed by Brownian Motion (diffusion) and wind currents. A balance is formed.

    Sea Water does not expand as much as air. Currents mix it similar to to air as well as diffusion. Some Electrolytes are highly soluble causing a more homogenous mix. On a "per molecule density level", it is mixed more homogeneously that in earth.

    Earth (heavy elements and compounds) is more separable due to gravity. Diffusion is the least. Layers in the earth are more separated by a per molecule density. Currents still cause mixing. Earth is most opaque to radiation of the three. Earth molecules have more energy levels. Basically the elemental atoms have more transitional energy levels for the electrons, and more degrees of freedom for the molecules.
    It absorbs and re radiates more radiation especially in infra red range.

    All increase in pressure with increased depth.

    Different physical processes dominate in air, water and earth.

    For example, at the bottom of the Marianna Trench, it is cold. Yes there are currents in the sea and warmer water can reach into the trench due to shape of ground, etc. However, 'generally' it is cold. This is because currents mix/move the temperature. Hot water rises, and cold water sinks. Very slight expansion of water by warming thus atmospheric physics does not apply here. Secondly less sunlight reaches the bottom than the top. Sea is still translucent relatively to earth and has colloidal particles. Particles absorb more sunlight that the water. Particles way down would receive very little thus the colder temperature. Note sea is more uniform relative to earth.

    Now why is the center of the earth so hot:

    Think of packets of energy and how much different ways you can pack such packets in a molecule.

    Solids of one type of element generally have less degrees of freedom or ways of storing packets of energy, relative to the same element in a gaseous form. Solids have "molecular attraction" which limits the energy in the form of potential energy. Gases are above this limit. Different energy packings for different the states of matter.

    The more down the periodic table, generally the more opaque to light. Especially heavier elements/compounds by atomic number. This is because they have many more electrons, and which corelates to having more ways to pack packets of energy. Consider the opaqueness as to a way in which solids absorb/interact/emit more frequencies of radiation, especially in infra red.[1 mark]

    Molten earth (heavy element and compounds) also follow a density distribution. Usually one of the lighter compound, silica, comes up to the surface of the Earth. You can expect heavy compounds and elements to be down in the planet's core. Like Iron, Silver, Gold and Lead. Gold, silver and lead is relatively rare. It is believed that earth has an iron core [1 mark]

    Solar radiation hits the earth's surface (Air and water are more transparent to light and this may be related to the degrees of freedom or energy levels changes being small and narrowband relative to heavy elements) High energy XRays and other radiation are absorbed by the heavy elements and compounds. When surface earth is heated it is re-radiated (in all direction) in lower infrared. The inner heavier erth is more opaque to that radiation and obsorbs it and has a broader band of absorption. The effect increases as you go down. However the Earth rotates and outer layyer are not always in the sun and radiatte (up and down) and cool. It will not be as opque as the core, thus will not be so much heasted by the core. Equilibrium is reach with the inner core being hot mostly because it is truly opaque and absorves. An anology would be a black ball core nested in a giant glass casing and place in the sun
    Selfishness is the gateway to Self Destruction
    Lack of "Wokeness" is to be reincarnated as a tapeworm, whereas more awareness give rise to higher level feelings and relations with others

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    Thanks for posting the detailed answer. Still not fully recovered interestingly. Part of why I've not been active. Please continue with the series because it is very informative. Once I've fully recovered I'll be back giving my layman view on the topics. Again - I am still a bit surprised nobody else is jumping on it. Even if you don't have college experience in the specific field, giving a POV on the topic helps. And helps others with the final answers.
    Knowing the solution doesn't mean knowing the method. Yet answering correctly and regurgitation are considered "learning" and "knowledge".

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    Quote Originally Posted by khat17 View Post
    Thanks for posting the detailed answer. Still not fully recovered interestingly. Part of why I've not been active.
    Hope you make a full recovery soon

    Quote Originally Posted by khat17 View Post
    Please continue with the series because it is very informative. Once I've fully recovered I'll be back giving my layman view on the topics. Again - I am still a bit surprised nobody else is jumping on it. Even if you don't have college experience in the specific field, giving a POV on the topic helps. And helps others with the final answers.
    Totally agree. It is nice to bounce ideas between different heads Even Einstein was seeking someone to get ideas from. You have an idea and put it out and someone else can LOGICALLY take it apart and analyze it and give you logical feedback. And visa versa, you can do the same for someone else's idea. Multiple theories can exist until experimental rules it out, or shows it needs modification. Conclusion is what should not be drawn in hast.

    I am surprise no Physicists or scientists are here too. Maybe it is a symptom of our education system or maybe I need to incentivize people and students with a cash prize at the end.
    Selfishness is the gateway to Self Destruction
    Lack of "Wokeness" is to be reincarnated as a tapeworm, whereas more awareness give rise to higher level feelings and relations with others

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    Quote Originally Posted by crosswire View Post
    Hope you make a full recovery soon


    Totally agree. It is nice to bounce ideas between different heads Even Einstein was seeking someone to get ideas from. You have an idea and put it out and someone else can LOGICALLY take it apart and analyze it and give you logical feedback. And visa versa, you can do the same for someone else's idea. Multiple theories can exist until experimental rules it out, or shows it needs modification. Conclusion is what should not be drawn in hast.

    I am surprise no Physicists or scientists are here too. Maybe it is a symptom of our education system or maybe I need to incentivize people and students with a cash prize at the end.
    LoL. I bet persons will be more likely to participate to get some Digicel/FLOW credit at the end of the week. Ay sah...
    Knowing the solution doesn't mean knowing the method. Yet answering correctly and regurgitation are considered "learning" and "knowledge".

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    Quote Originally Posted by khat17 View Post
    lol. I bet persons will be more likely to participate to get some digicel/flow credit at the end of the week. Ay sah...
    dwl

    ..........................
    Selfishness is the gateway to Self Destruction
    Lack of "Wokeness" is to be reincarnated as a tapeworm, whereas more awareness give rise to higher level feelings and relations with others

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