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Thread: energy mass ratio

  1. #1 energy mass ratio 
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    how much maximum mass can you squeeze in lets say in a square cm. how much maximum energy can you squeeze in say a square cm.?


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    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by parag1973 View Post
    how much maximum mass can you squeeze in lets say in a square cm.
    In a square cm? Zero.

    In a cubic cm: A neutron star has a density of about 600,000,000,000 kg / cm3. This is probably the densest thing we know of.

    how much maximum energy can you squeeze in say a square cm.?
    Mass and energy are the same thing, so the mass above is about 5 x 1028 joules. But I'm not sure what you mean by "energy" and how it could be compressed.


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    Moderator Moderator Markus Hanke's Avatar
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    The upper limit of any mass distribution is given by the Tolman-Oppenheimer-Volkoff limit; the densest objects we know of are neutron stars, in which case the limit would be about 2 solar masses for a star with a radius of just 11km. This means, in practical terms, that one teaspoon of this neutron star's matter would weigh as much as 900 great pyramids of Giza.
    If this mass limit is exceeded the object will undergo a gravitational collapse and become a black hole.
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  5. #4  
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    Quote Originally Posted by Strange View Post
    A neutron star ... is probably the densest thing we know of.
    Doesn't a singularity have infinite density (thereby making it the most dense)? So, infinitely dense objects with finite mass... So you could hypothetically pack in an infinite quantity of singularities and have infinite mass :O Though the prior assumptions might be wrong.
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    Moderator Moderator Markus Hanke's Avatar
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    Quote Originally Posted by brody View Post
    Quote Originally Posted by Strange View Post
    A neutron star ... is probably the densest thing we know of.
    Doesn't a singularity have infinite density (thereby making it the most dense)? So, infinitely dense objects with finite mass... So you could hypothetically pack in an infinite quantity of singularities and have infinite mass :O Though the prior assumptions might be wrong.
    Yes, but it is unlikely that the singularity in the black hole is actually physically real; it emerges from General Relativity because that theory does not account for quantum effects, which are clearly significant here. Once we have a consistent model of quantum gravity ( which we don't yet ) chance are fairly high that no singularity appears in black holes.
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    consider a hypothetical sitaution. we align the magnets in such a way that a nealry perfect sphere is formed in space. This sphere will be in the centre of the magnets. now how much strong magnetic field is needed to disrupt the spherical structure. Note that these magnets hold on to their position due to mutual forces of attraction and repulsion. The magnetic field of all the magnets should be varied simultaneously. The sphere formed by such magnet arrangement has got magnetic
    potential as it is in the centre. I want to know what is the maximum magnetic field that a magnet can have such that it would not disrupt the arrangement of magnets.
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    Moderator Moderator Markus Hanke's Avatar
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    Quote Originally Posted by parag1973 View Post
    consider a hypothetical sitaution. we align the magnets in such a way that a nealry perfect sphere is formed in space. This sphere will be in the centre of the magnets. now how much strong magnetic field is needed to disrupt the spherical structure. Note that these magnets hold on to their position due to mutual forces of attraction and repulsion. The magnetic field of all the magnets should be varied simultaneously. The sphere formed by such magnet arrangement has got magnetic
    potential as it is in the centre. I want to know what is the maximum magnetic field that a magnet can have such that it would not disrupt the arrangement of magnets.
    I don't understand the connection to the OP...? Why are we suddenly talking about magnets ?
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    Quagma SpeedFreek's Avatar
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    What shape are the magnets?
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    The point is not about magnets. The point I want to make is that at the centre of the sphere large amounts of energy is stored in the form of magnetic potential. I want to know what is the maximum amount of energy we can store in space(vaccuum)
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  11. #10  
    Moderator Moderator Markus Hanke's Avatar
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    Quote Originally Posted by parag1973 View Post
    The point is not about magnets. The point I want to make is that at the centre of the sphere large amounts of energy is stored in the form of magnetic potential. I want to know what is the maximum amount of energy we can store in space(vaccuum)
    I think the magnetic potential at the center would be exactly zero. Consider Gauss law for magnetic fields :



    In my understanding, what this means is that the net flux through any closed surface around an arrangement of magnetic sources is zero. Since this sphere is obviously symmetrical, the same should hold true for the inside of the sphere, in other words, even sitting in the center you shouldn't be able to see a magnetic monopole surrounding you. Therefore the magnetic field lines at the center of the sphere must cancel each other out.
    Actually I am not 100% sure that I am correct with my intepretation - comments, anyone ??
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