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i'm trying to find out what the decay energy is for neutronium. i'd like to find out if it would be a suitable fuel source for our civilization's needs (if we ignore the problem of extracting it from somewhere.)

Qmechanic
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    Where would you extract it? You can't get close to a neutron star, because of the extreme tidal effect, see https://physics.stackexchange.com/a/631427/123208 And if it's a young neutron star, you also have an intense magnetic field and pulsar radiation to worry about. – PM 2Ring Dec 10 '21 at 19:09

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Neutronium doesn't form as a stable bound state under normal conditions (i.e. pretty much anyplace outside the conditions found in a neutron star). If it did, it would be element number zero in the periodic table.

It doesn't form as a stable bound state because the residual strong force/nuclear binding force between two neutrons isn't quite sufficient to bind them, and because a free neutron is not stable. To only slightly oversimplify, bound neutrons are stable only dynamically, and only because their decay products cause protons to become neutrons at the same rate that neutrons decay to protons.

So, it would decay in a time frame that is too rapid to have practical use as a nuclear fuel, if it were formed in a laboratory (it does not exist in nature outside neutron stars).

It is extremely radioactive; its only legitimate equivalent isotope, the free neutron, has a half-life of 10 minutes, which is approximately half that of the most stable known isotope of francium. Neutron matter decays quickly into hydrogen.

As a result of the Second Law of Thermodynamics, the formation energy will always exceed the decay energy in any actual physical system.

Furthermore, since it does not exist as a stable bound state, it would not be a useful way to store energy as a substitute for a battery.

Also, since it is electromagnetically neutral, even if you tried to "ionize it" since it has no electron shell, containing it in a compact fashion would be challenging. You couldn't use a magnetic cage to do so, and if you made enough of it, it would behave chemically as a non-reactive noble gas.

So, neutronium could not serve as a viable fuel source for any civilization.

ohwilleke
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