Neutron Star

  1. So how much denser than is a neutron star than an atom? Is it called a neutron star because electron's orbital effect no longer exists/acts the same, so as to no longer cause 99.99% of everything to be space?
     
  2. jcsd
  3. SteamKing

    SteamKing 9,915
    Staff Emeritus
    Science Advisor
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    A neutron star is composed of other things besides neutrons. The crust may still contain some chemically recognizable elements, while no one is certain what type of matter is contained in the core.

    http://en.wikipedia.org/wiki/Neutron_star

    The second paragraph discusses the density of neutron stars versus the densities of other types of matter.
     
  4. Wow denser than the nucleus of an atom, would that make it so that the strong nuclear force has a detectable field on a macroscopic sense outside of the neutron star?
     
  5. Drakkith

    Staff: Mentor

    Nope.

    It's called a neutron star because a great portion of the star is believed to be composed of neutrons. There should also be a mix of protons and electrons as well, with a greater proportion of neutrons to other particles as you get closer to the core. (Because the pressure is higher near the core, which makes it more favorable for protons to combine with electrons and form neutrons)

    Also, it is a misconception to say that 99.99% of everything is empty space. Fundamental particles are thought of as point-like, meaning they have no dimensions. Yet atoms still have "sizes" based on how the electrons occupy their states around the nucleus. It's actually kind of complicated, and you'd have to look into Quantum Mechanics a bit to understand it.
     
  6. Chronos

    Chronos 10,217
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    Great explanation, drakkith, aside from being incorrect.
     
  7. Drakkith

    Staff: Mentor

    Care to elaborate?
     
  8. Chronos

    Chronos 10,217
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    Gold Member

  9. Drakkith

    Staff: Mentor

  10. What part of quantum Mechanics, is it very easy explainable, or is there a paper i can read/ video I can watch to learn about it?
     
  11. I would say that you were incorrect in saying that it's a misconception to say that 99.99% of everything is empty space when you also said that the fundamental particles are point-like. They are point-like but interact with each other over a measurable distance, creating the "size" of the atomic system itself. The space within this system of interaction is almost entirely empty space.

    That is why within a neutron star, we consider it to be made almost entirely out of neutrons because the matter is compressed so densely, that the space an atom occupies is compressed to the point where the atomic systems are essentially compacted together. At least in a neutron star, we can say with a fair amount of reasonable certainty, that it contains matter that is made up of far less than 99% of empty space.
     
  12. The 4th grade science definition of matter is something that has mass and takes up space, so by taking up space does this mean the size of the atomic system, even though the atomic system itself isn't taking up space the same way as we think that a desk does?
     
  13. Correct, it is referring to the fact that atoms interact with each other at a distance, relative to the size of their atomic systems.
     
  14. Drakkith

    Staff: Mentor

    If fundamental particles are point-like, and if you believe that only particles are "physical" objects capable of taking up space, then 100% of everything is empty space. However if you consider that particles are believed to be "excitations" of fields then you could say that the space inside an atom is filled with these fields and is not empty.

    Atoms are not actually a single size. The electrons occupy orbitals and have certain locations that they are most likely to be found. However, due to the wavelike nature of particles, there is a small chance that an electron can be found nearly anywhere in the universe. (Very, utterly, extremely small chance, but a chance nonetheless.) Protons and neutrons follow similar rules, but due to their much larger masses and the effect of the strong force the area where you are most likely to find them is much, much smaller than that of an electron. (Which is why a nucleus is so very tiny compared to the size of the electron orbitals)

    That's why I said that the issue of empty space is complicated. Depending on how you look at it the atom could be 100% empty space or it could fill most of the universe at once.
     
  15. Basic subatomic particles are most definitely not point-like aside from electrons. At the most, Protons and Neutrons have a somewhat easily measurable size, and do take up a physical space. It is this space, that most of the atom's matter is located. The atomic system itself though, extends for as far as the electrons orbitals reach because that is that atom's area of influence. It is this area that atoms normally interact with each other linking up to create molecules that comprise the rest of an object. This is why most matter is considered to be 99% empty space.
     
  16. Strictly speaking, it's not pressure that makes it favorable, but availability of extremely energetic electrons.

    When neutron star is being formed, electron "gas" becomes more and more degenerate, more and more of electrons move at relativistic velocities, and reach enough energy for p + e -> n + nu reaction. Conversely, normally unstable neutrons cannot decay, since there is no quantum-mechanical "space" for resulting not-energetic-enough electron.
     
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