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The shape of 'things'.

  1. Sep 10, 2013 #1
    Forgive me if this is posted in the wrong section, but it relates to the compact heavies of the universe.
    Generally, we seem to have the classical idea of what an atom 'looks' like in our minds, a small a spherical body joined with other small spherical bodies which make up the different elements that exist. What happens to the spherical shape when things get distorted by massive gravity?
    I know with neutron stars all the empty space between the electrons and nucleus gets compressed away, which forces the electrons into the nucleus, and all that is left are neutrons (not sure about the process, but just go with it). The neutrons are basically touching each other, but is that all? Are the neutrons also spherical at these pressures, or do they start to become distorted also?
    I would imagine that they would essentially become cube shape at the core of a neutron star to push out the remaining 'free space' between the touching spherical neutrons. Is there a correlation between the distortion of a neutron to a cube and the formation of a black hole?

  2. jcsd
  3. Sep 10, 2013 #2


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    Neutrons are not billard balls, they are not "touching" each other. The region of a neutron star where neutrons dominate is (probably) more like a liquid. Neutrons can pass through each other, and overlap, and so on, there is no need to get deformed. At some point, it gets tricky to define "shape" at all. There is certainly no cube-shaped neutron.
  4. Sep 15, 2013 #3
    Thanks mate, you seem to have a comprehensive understanding of most things astronomical.
    What are the reasons that the neutrons are able to occupy the same space at the same time in the example that you give?
    I would have thought that the neutrons would have individually been very 'solid'. Do you know whether they are compressed at all?

  5. Sep 15, 2013 #4


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    It is a quantum mechanical phenomenon. Two particles, like neutrons, can occupy the same place at the same time if they occupy different "states". A simple example would be two neutrons in a helium nucleus. They can occupy the same place at the same time because they have opposite "spin". Spin is just one of the several properties a particle has, and as long as at least one of those properties is different from another particle they can occupy the same place.

    Each neutron itself is very "solid" depending on what you mean by that, though you cannot compare them to small solid balls. They have several properties that seem very disturbing if you aren't familiar with Quantum Mechanics, such as the ability to occupy the same place at the same time as another neutron. Note that the "shape" of a neutron is dependent upon the arrangement of the three quarks that compose it, and it takes a phenomenal amount of force to really do anything with these quarks. The color force (the force that holds the quarks together) is unimaginably powerful. So powerful that a very very small "bleed-through" of this force is responsible for holding particles together inside the nucleus of an atom, and even though it is only a very small fraction of the strength of the main color force, it dominates over the repulsive electromagnetic force from up to about a hundred protons combined.

    Does that make sense?
  6. Sep 16, 2013 #5
    Thanks Drakkith, I have heard/read mention of spin before regarding quarks, as well as 'up and down' quarks. That slots another of the puzzle pieces together for me. I was going to mention quarks in the original post, but I know even less about those than the bigger particles they make.
    Mind you, I have a book waiting to be read on the bed side by Brian Cox and an associate which delves into some of this also, so hopefully some of that will sink in.
    There seems to be a very strong correlation to the more fundamental the particle, the more powerful its immediate forces become.
    I think I also have heard mention of the maximum number of protons which can be held together effectively in the nucleus which is why our periodic table of the elements only goes so far, with the last 10-15 being (very temporarily) man made.

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