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My random thoughts about the sun, black holes, and gravity.

  1. Mar 3, 2012 #1
    I'm a huge noob and I don't know much about physics and space and stuff, but I was thinking about this in the shower today..

    Anyone care to comment? Or correct me on anything?

    Ok, so I was talking about to Daniel about Gravity, the Sun, and Black Holes.. (Yes we are ghetto nerdy xD) And i may have gotten some stuff wrong.. but eh, critical thinking randomly!!

    Sooo I was thinking.. what the heck are black holes? Dead Suns.. and what are suns? They are this thing... Thats burning this stuff.. And what is gravity? ...We dont know! We can only see its effects. We cant bottle some gravity... or as far as I know recreate it.

    Sometimes I have irrational fears that the earths gravity is just gunna randomly quit and we're all gunna go flying out into space... So Im thinking.. What is gravity? I think and think and i STILL dont know.. So what is at the center of the earth? The single point of where the earths gravity starts.. right? Well... If you were to go to the center of the earth.. would you be all smushed? and how can we be sure?

    Or.. I think there's something about gravitys centers that we dont know yet. There's some aspect thats just.. completely missing. Perhaps something to do with super hot stuff spinning really fast? I dunno.. thats the big missing part from what I've been thinking about.

    Anyway - so.. some suns turn into Black holes... but why? The sun is some sort of core, prolly metal.. and theres all this STUFF orbiting it.. and the sun is fusing/fissioning/whatever it all the time.. and spitting bits of it out via solar winds and stuff.. so EVENTUALLY it will use up all the stuff that its fusing/fissioning and then what? it gets bigger, right? big enough to swallow the earth. But why? GRAVITY!??? Because maybe that the gravity isnt pulling everything in right now is cuz of the stuff being fused/fissioned somehow RESISTS gravity.. maybe the space between the atoms has its own sort of 'gravitational field' that resists the big field of the sun.. This is totally me speculating right here, but yeah it would make a bit of sense in my mind. So once all the stuff gets used up, it starts to fly out, because.. the core gets hotter with less stuff to burn?? So it gets hot and expands? Till the point where.. it gets tense? and like a balloon thats blown up.. when you pop it it suddenly explodes and goes back to being small?

    So the sun dying may be kinda like a marshmallow in the microwave.. After the sun uses all its stuff, theres still a bit of stuff left right around the core that gets really hot that pushes the rest out until.. something happens and then it shrinks.. and shrinks until the gravity doesnt have anything left of the 'stuff' left to push AGAINST the gravity, and the gravity pretty much turns in on itself and creates the 'black hole' Which may not even be a hole!! It might be that super dense core... and then it just takes everything and smushes it... not suck it "in" like as in a hole? but just takes all the "Air" out of all molecules and smushes it all into 1 big huge super dense thing.. It sucks all the empty space away from matter! So its SUPER Small!! Like, theres no coming out of "another side" cuz a 'black hole' may not be a hole but just a black sphere of mass that almost 'magnetically' sucks everything to IT.. essentially destorying the order that the molecules of stuff around it is in... But then black holes die. but why?

    And when the sun dies.. they never told us this in science that i can remember.. The Sun will loses a lot of its mass when it expands, and there is a chance that some of the planets will get PUSHED AWAY instead of being engulfed.. as their orbits will changed based upon the different gravities and stuff! WOAH! thats like... weird, lol.

    and black holes... they say space and time gets distorted.. but man thats a whole nother can of worms, and im not even gunna try and understand time altering, lol. I get blown away by the whole "Twin trip" thing by itself.

    And another thing is... outside of the event horizon is anohter egg shaped unit called Ergosphere in which its impossible to stand still in... cuz its pulling you TOWARD the event horizon. Ok i can buy that.. but why egg shaped? If you are right "On top of" the event horizon, you arent getting pulled toward it, but you'd be super pulled toward it if you were near the equator-ish area because the egg shaped ergosphere.

    BUT an interesting question is - would it crush it into a sphere like I previously thought? Or would it be like folding/unfolding a piece of paper? Like.. unfolding and crushing it into a 2D plane? Would that be why galaxys and stuff are spiral shaped instead of sphereical? Wouldnt black holes actually RIP dimentions apart, changing everything into 2D instead of SIMPLY crushing it together in a still 3D environment?

    Or perhaps is there some force acting upon a black hole's ergosphere similar to the tides of the earth? This seems unlikely, but i thought about it.

    Buttt Stephen Hawking put a theory out there stating that black holes emit small amounts of thermal radiation... and he suggests that black holes technically evaptorate over time because they loose their mass via emission of the stuff it sucks up. So does this mean that heat is technically faster than light? and faster than dark? becuase it can escape the event horizon? is this why absolute zero cannot exist? Because heat is everywhere whereas light may not be everywhere since its slower?

    Also wouldnt the earth turn into a black hole too? Daniel says its mass is too small. But if it is essentially a hot burning core with gasses and crap around it.. just with a crust over top of it.. Would we know if the core started to like die, like the sun would? would we see the effects of the gasses 'getting bigger' like the sun? More earthquakes? Hotter environment? I duno just a thought.
  2. jcsd
  3. Mar 3, 2012 #2


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    Stars are ball of hydrogen and helium, fusing the hydrogen in the core into helium, and if massive enough the helium into carbon and oxygen. More massive stars make heavier elements.

    What is anything? The only correct way to answer that question is by explaining the properties of it, including mass, charge, how strong it is, it's effect on other things around it, etc. We know how gravity works to such an accurate degree that we can predict how things will occur hundreds to thousands of years from now and thousands of light years away. We can't bottle gravity any more than we can bottle electromagnetism. Both are one of the 4 forces of nature, not matter, which we can bottle.

    The core of the Earth is at it's center. The gravity does not start there, as all of Earths matter contributes to gravity, not just the center. And yes, we would be crushed. There have been wells and tunnels drilled thousands of feet deep where we can measure the increasing pressure of the above rock and earth. There is no reason to think this simply stops happening at the core.

    Gravity is a force and has no center. Did you mean the Earth?

    Simply due to increasing mass in the core of large stars. Eventually they get so dense they can't support themselves against gravity, and BOOOOM. Supernova.

    The core of the Sun is mostly Helium and Hydrogen with traces of heavier elements. Once it uses up most of the Hydrogen the core will collapse until it heats up enough to begin fusing Helium. Since at this point in time there will also be a Hydrogen fusing shell, all that extra energy puffs out the stars outer layers.

    Heat is simply the motion of atoms and molecules in an object. In a gas or plasma these particles shoot around in different directions at super fast speeds, which on the large scale results in increased pressure of the gas or plasma. There is no field that pushes it apart.

    It expands until the energy being released is equal to the energy being generated, at that point it will reach equilibrium and stop expanding. Once the helium is used up it will start to contract again. But this isn't a sudden event like a balloon bursting, it happens over many many years.

    First, the Sun is not nearly massive enough to ever turn into a black hole. A black hole is not a literal hole in space. It is simply a massively dense remnant of a star where the force of gravity is strong enough at a certain distance from it that not even light can escape. If you were to replace the Sun with a black hole, which isn't possible, but if it was the Earth would still spin around in it's orbit with no change. The force of gravity from a black hole is no different from anything else except when you get close to it thanks to the fact that all that mass is no compressed into a tiny tiny volume. Black holes will only die if Hawking Radiation exists, and even then it will take many billions of years for them to evaporate.

    They won't really get pushed away, it's just that the Sun will gradually lose mass, causing the orbits of the planets to move outward.


    It is simply frame dragging. http://en.wikipedia.org/wiki/Frame_dragging
    No, hawking radiation is generated and released outside the event horizon. http://en.wikipedia.org/wiki/Hawking_radiation

    The core of the Earth is most likely solid iron and nickel and is surrounded by liquid metal and rock in the mantle. There are no gasses like in a star. It is also not burning. It is simply still very hot because the Earth has not had time to cool off from the heat of it's creation. No worries, we aren't going to collapse into a black hole. The Sun is several times too small, and we are thousands of times smaller than the Sun, so there's no chance of that happening to us.
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