A spoonful of neutron star

[AluminumStudios]

We've all heard many times how a spoonful of neutron star material would weigh millions of tons (or more) on Earth and such. But what I want to know is if we could theoretically somehow take a spoonful of a neutron star, wouldn't it explode insanely violently the second it was no longer in the gravitational field that compressed it?

Neutron stars are unimaginably hot. At those temperatures any matter should want to expand as a gas. So if we could borrow the transporters from the starship Enterprise, and beam a spoonful of neutron star material to Earth, wouldn't it explode rather than remaining a super-dense, super-hot clump of matter?

Also, if it exploded, what would it release? Would it be an unbelievable blast of particle radiation (neutrons), or would it be more like the shower of various particles seen inside the colliding beams of particle accelerators due to the high energies involved and neutrons colliding with other particles?

* I know that the Enterprise's transporters have a limited range and even with boosting the annular confinement beam probably couldn't get a lock on material from a neutron start, this is in theory ;-)

 

[Biftheunderstudy]

According to the back of the envelope calculation that I just did,

1 tsp = 5E-3 m^3
Neutron star density = 10E17 kg/m^3
So, there are ~10E31 neutrons in a teaspoon of Neutron star

A typical beta decay has ~1MeV, so there are ~10E37 eV available as energy in the form of neutrinos and electrons.

The hiroshima bomb was 60E9 J compared to the 1E18J here....but remember, a large chunk of that will be in neutrinos and that is only the average beta decay. The other part will be electrons. Also this is the total energy if all the neutrinos beta decayed and says nothing about the time scale.

Caveat: My math could be wrong...

Edit: Hiroshima was 60E12 and was 40 kiloton (?) ish, we've detonated 50 Megaton bombs before, thats 60E15. Astrophysically, this is rather small. A really big supernova/gamma ray burst is 10E51 ergs or 10E48 Joules, AGN create radio lobes etc. with a energy of creation of something like 10E53 ergs...these are among the most energetic things in the observable universe. This is also a really naive calculation that assumes that all of the neutrons beta decay neglecting anything about recombination of the protons into hydrogen or that sort of thing and says nothing about the time scale that this happens over, it could be a slow burn that doesn't do much of anything.
Here's an interesting page:
http://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)

 

[PsiStar]

so ... there would be a really big bang

 

[Ninjahedge]

Just wait 'til you add milk!

 

[PsiStar]

and thus, a milky whey

 

[Ninjahedge]

No whey!

 

[KIAman]

First, scientists aren't sure what exactly is the composition of a neutron star and their best theories show several layers of matter with the outer layer of ions and the core of quark soup. From which portion does the "spoon" grab?

Second, other than the thermal energy of the extreme temperature, there isn't any specific potential force that would cause an explosion. There is no matter-energy conversion nor any chemical reductions to release energy.

The best it could do was simply destabilize as it adapts to the new surroundings aka, weak gravity, nitrogen/oxygen/carbon/water in the air.

My best guess is that the spoonful would rip through the crust of the earth as it destabilizes and simply be assimilated with the earth's mantle causing a minor earthquake.

But this is really up to the imagination. This is like asking "what would happen if the sun just dissapeared?" The answer to the question is "it's impossible."

 

[Ninjahedge]

KIA, you are better than I for ignoring the whole ST "magical teleporter" MOI that is being proposed, but I am not sure he is asking about anything besides the stored kenetic energy from being atomically compressed.


I do not know if there would be any actual nuclear reprocussions to the expansion, but when you compress solid matter that greatly and then relieve it of its confining pressure, you will get a significant reaction.

I guess it all depends on where you put it. You zap it in at 100' above the surface and all I think you would get, at most, would be a shockwave. You wuold also definitely get some local freezing as the sample expands and cools.

But if you were to put this in direct contact with solid matter like 100 miles below the surface, I believe the expansion produced would create a sizable shockwave transferring through the magma and eventually the earth's crust.

I guess it all depends on how compressed this matter really is. Maybe nothing woud happen. Maybe a neutron star is actually at a state of stability that was achieved by compaction beyond the normal range possible by smaller scale physical means.

Maybe someone would make a movie about it.

The possibilities are endless (IN 3D!!!!!!!) >quark<

 

[Elias824]

KIA, you are better than I for ignoring the whole ST "magical teleporter" MOI that is being proposed, but I am not sure he is asking about anything besides the stored kenetic energy from being atomically compressed.


I do not know if there would be any actual nuclear reprocussions to the expansion, but when you compress solid matter that greatly and then relieve it of its confining pressure, you will get a significant reaction.

I guess it all depends on where you put it. You zap it in at 100' above the surface and all I think you would get, at most, would be a shockwave. You wuold also definitely get some local freezing as the sample expands and cools.

But if you were to put this in direct contact with solid matter like 100 miles below the surface, I believe the expansion produced would create a sizable shockwave transferring through the magma and eventually the earth's crust.

I guess it all depends on how compressed this matter really is. Maybe nothing woud happen. Maybe a neutron star is actually at a state of stability that was achieved by compaction beyond the normal range possible by smaller scale physical means.

Maybe someone would make a movie about it.

The possibilities are endless (IN 3D!!!!!!!) >quark<

Isnt a nuclear explosion just a shock wave, its more of a matter of what i picks up in that shock wave, like maybe people and buildings. It would be pretty interesting Espically if the shock wave is anything close to what one of the previous poster came out to.

 

[Ninjahedge]

Elijas, a nuke causes a shockwave, but that is because it is changing matter to energy, not just expanding back to a stable state.

I do not think this would go nuclear if it was allowed to spring back, although some stuff may be sprung out if the kinetic energy released id greater than the nuclear attraction/repulsion fueling it.....

 

[willem2]

Elijas, a nuke causes a shockwave, but that is because it is changing matter to energy, not just expanding back to a stable state.

I do not think this would go nuclear if it was allowed to spring back, although some stuff may be sprung out if the kinetic energy released id greater than the nuclear attraction/repulsion fueling it.....

The only thing that prevents collapse in a neutron star, is that the
neutrons have very large velocities. If you remove the surrounding
material, all those neutrons will fly off, with very large speeds,
much larger than those in a nuclear explosion, enough to
split any atom.
About half of those neutrons will collide with something in the earth
in the first hundreds of metres.
There will be about 10^12 kg of neutrons in a spoonful of neutron star.
I think the effect would be similar to a 10^12 kg of U235 exploding.
I don't think anyone on earth would survive this.

 

[kotss]

Helps the medicine go down.... Everyone knows this.

 

[Biftheunderstudy]

The only thing that prevents collapse in a neutron star, is that the
neutrons have very large velocities. If you remove the surrounding
material, all those neutrons will fly off, with very large speeds,
much larger than those in a nuclear explosion, enough to
split any atom.
About half of those neutrons will collide with something in the earth
in the first hundreds of metres.
There will be about 10^12 kg of neutrons in a spoonful of neutron star.
I think the effect would be similar to a 10^12 kg of U235 exploding.
I don't think anyone on earth would survive this.

No, a neutron star is supported by neutron degeneracy pressure. Neutrons, being fermions, can't occupy the same state a the same place because of the Pauli exclusion principle. This is the same mechanism that supports a white dwarf which is held up by electron degeneracy pressure.

They operate on the same principle as all stars, a balance between outward pressures and inward gravity. It so happens that neutron stars have very high rotation rates and so some centrifugal support is present as well.

The other part of this is that a free neutron is unstable, it has a half life of around 11 minutes before it decays into a electron and electron-neutrino. Neutrons in a neutron star would be considered bound and thus be stable against this sort of decay channel, if you took them out of the star they are no longer bound and will decay with a half life of 11 minutes.

You can work out how much energy this produces per second (the wattage if you will) via beta decay. What I posted above was the TOTAL energy after all of the beta decays, so there might not even be a shockwave.

 

[Ninjahedge]

Bif,

1st (anal) is that it is "centripital". Centrifugal is the perceived force that people think is being applied to them due to rotation, when the force itself is actually the opposite (pulled in, not pushed out).

2nd, I think what people are asking is if the neutron star will just "realize" it has no confining pressure anymore (gravity) and "spring" back to its natural state. Several different scenarios have been mentioned, including simple volumetric expansion, neutron ejection with colateral nuclear reaction, and "nothing" with neutron decay.

While I do not think the neutrons will just go shooting out in random directions, I do not think they will just sit there either. If the matter expands with no confining force capable of restraining it, we have the possibility of a sloppy dirty nuclear chain reaction party. If it expands, but that loss of energy causes other processes to come into effect reducing the neutrons back to "normal" atomic configurations, we would end up with some free particles, but most likely a concusive shockwave and a LOT of absorbed energy.

If it is in a semi-stable because of some other balance, such as centripital force, we might even see a further collapse into black-hole state.


The difficulty in this is that it is not physically possible to move that much compressed matter instantly to an area radically different from its current environment. So we can all theorize about what might happen, but until they are able to contain a sample of that matter in, say, an EM containment field powerful enoug hto keep it compressed (or stable) and we then just shut it off, we will probably never know what really happens.

If we are lucky, one of our formulas will be right and tell us before we need to replace the state of Arizona.....

 

[Biftheunderstudy]

1. Right you are, I don't know what possessed me to even type that...normally I would have just said rotationally supported, indeed this is the wording that I've used to describe some phenomenon in my thesis...

2. I don't think you can neglect the beta decay energy...especially since it's probably at least comparable to the kinetic energy of the neutrons coming out of confinement. Also, beta decay was easy to calculate. Try coming up with how much stored up energy there is in a ball of neutrons coiled up like a spring...doesn't sound easy. Next, you need to consider neutron capture and the activation of nearby mater which will then also decay.

All in all, there is a lot of energy available but the question is how quickly does it release it.

 

[willem2]

No, a neutron star is supported by neutron degeneracy pressure. Neutrons, being fermions, can't occupy the same state a the same place because of the Pauli exclusion principle. This is the same mechanism that supports a white dwarf which is held up by electron degeneracy pressure.

This is actually exactly what I meant. Because the neutrons must occupy different states, they need to occupy states with very high energies. You can get some idea of this using the uncertainty principle

The density of a neutron star is about 4*10^17 kg/m^3 (in the middle, scooping up a spoonful from the surface will produce only a tiny fraction of the energy when exploding)
This is 2.4 * 10^44 neutrons/m^2 (multiply with 1000* avogrado's number)
A cube of 1m^3 neutrons will have 6.2*10^14 neutrons on each edge, so the distance between neutrons will be 1/6.2*10^14 = 1.6 * 10^(-15)m
According to the uncertainty principle (uncertainty in position)*(uncertainty in momentum) >= h/(4 pi)

This means that (uncertainty in momentum)>= (6.6 * 10^-34) / (4 pi * 1.6 * 10^(-15)) = 3.2 * 10^-20 Kg*m/s.
This corresponds to a speed of 1.9 * 10^7 m/s, so about 6&#37; of light speed.
Thats about 2MeV for each neutron, rather less than I tought.

Still about half the neutrons will immediately collide with atoms in the earth, producing about 10^25 J.

Note that the number of neutrons in a teaspoon calculated earlier in this thread is much too low. I'm using a 0.0025 ml teaspoon and a density of 4*10^17 kg/m^3 to get a 10^12 kg teaspoon with 6*10^38 neutrons

 

[Biftheunderstudy]

Note that the number of neutrons in a teaspoon calculated earlier in this thread is much too low. I'm using a 0.0025 ml teaspoon and a density of 4*10^17 kg/m^3 to get a 10^12 kg teaspoon with 6*10^38 neutrons

Check your math,
0.0025 mL = 2.5 E -9 m^3.
2.5 E -9 m^3 * 4 E 17 kg/m^3= 1 E 9 kg
1 E 9 kg / m_n = 5.9 E 35 neutrons / teaspoon

(I used slightly different numbers the first time around)

In any case, the energy per neutron is comparable. The average kinetic energy is on the order MeV while the average beta decay is also MeV. Since this is an order of magnitude estimate anyway, 1 MeV per neutron isn't much different from 5 MeV per neutron.

Timescale is rather important though, how quickly does each process deposit its energy into the environment?

 

[willem2]

Check your math,
0.0025 mL = 2.5 E -9 m^3.
2.5 E -9 m^3 * 4 E 17 kg/m^3= 1 E 9 kg
1 E 9 kg / m_n = 5.9 E 35 neutrons / teaspoon

(I used slightly different numbers the first time around)

In any case, the energy per neutron is comparable. The average kinetic energy is on the order MeV while the average beta decay is also MeV. Since this is an order of magnitude estimate anyway, 1 MeV per neutron isn't much different from 5 MeV per neutron.

Timescale is rather important though, how quickly does each process deposit its energy into the environment?

Sorry, now I was using a very small teaspoon, I meant 0.0025 l or 2.5 ml.
So that will still give 5.9 E 38 neutrons/teaspoon.

I don't think that 2 MeV neutrons can penetrate more than a few tens of metres of rocks, so a significant fraction of the 10^25 J will go into heating up and evaporating rock. I don't think we can save Arizona. I don't think I want to be on the same planet as 5.9*10^38 loose neutrons in any case.

 

[Ninjahedge]

Damn neutrons.

 

[Homerboy]

I'm just here to say "Awesome thread".

 

[QuantumPion]

Timescale is rather important though, how quickly does each process deposit its energy into the environment?

Free neutrons have a half-life of about 10 minutes. So if you had 1e9 kg of neutrons (~6e35 neutrons) then after 1 second, 6e35*(1-e^(-1/600)) = ~1e33 neutrons would decay. According to the chart of nuclides, the beta energy for neutron decay is ~300 keV. 300 keV*1e33 = 4.8e19 J or about 11,000 megatons of TNT.

This would be an interesting way to destroy an entire planet, because unlike a nuclear fission/fusion bomb, where the reaction is contained for a microsecond and then ends, these free neutrons would spread out as they heat up but continue to decay. It would ignite the atmosphere and melt the whole surface in a matter of minutes (3 million megatons of tnt of betas after 5 minutes).

 

[Evadman]

I just wanted to chime in on the transporter. The number of neutrons in a teaspoon would have a total energy of roughly 1.5 &#215; 10^23J using data supplied elsewhere in this thread. That means in order to transport the neutrons off the star (mass to energy then back to mass conversion) the amount of energy transferred would be roughly equivalent to:

The total energy from the Sun that strikes the face of the Earth for a week
5 times the estimated energy contained in the world's coal reserves
4 times the identified global uranium-238 resources
3 times the estimated energy contained in all the world's fossil fuel reserves
3 times the estimated total energy released by the 2004 Indian Ocean Earthquake
More than 20 teratons of TNT. (20,000,000,000,000 tons)

It is within a rounding error of being the approximate energy released in the formation of the Chicxulub Crater in the Yucat&#225;n Peninsula. The asteroid that hit us and marks the Cretaceous/Tertiary boundry and caused a 110 mile crater.

It's not far off from the total power output of the sun for 1 second (3.86&#215;10^26). If we could harness a significant portion of the sun's energy output (maybe a Dyson Sphere) we could do this. anyway, I don't want to be on the planet when this is tried, or in the ship trying to transport it.

 

[Ninjahedge]

Wouldn't it be easier to just teleport the earth to the neutron star instead?

 

[Gibsons]

Free neutrons have a half-life of about 10 minutes. So if you had 1e9 kg of neutrons (~6e35 neutrons) then after 1 second, 6e35*(1-e^(-1/600)) = ~1e33 neutrons would decay. According to the chart of nuclides, the beta energy for neutron decay is ~300 keV. 300 keV*1e33 = 4.8e19 J or about 11,000 megatons of TNT.

This would be an interesting way to destroy an entire planet, because unlike a nuclear fission/fusion bomb, where the reaction is contained for a microsecond and then ends, these free neutrons would spread out as they heat up but continue to decay. It would ignite the atmosphere and melt the whole surface in a matter of minutes (3 million megatons of tnt of betas after 5 minutes).

hm, wow. It's an exploding explosion of explosions.

There's also the issue of what happens when you start hitting a lot of nuclei with gobs of neutrons at very high energies, you'd certainly get some fission events, right?

For that matter, the protons that remain after the beta decay will have plenty of energy too - wouldn't they be able to form deuterium or tritium with all the neutrons around, at least early on when the density is so high? And if that happens, you could then get fusion to helium?

 

[willem2]

I just wanted to chime in on the transporter. The number of neutrons in a teaspoon would have a total energy of roughly 1.5 × 10^23J using data supplied elsewhere in this thread. That means in order to transport the neutrons off the star (mass to energy then back to mass conversion) the amount of energy transferred would be roughly equivalent to:

The total energy from the Sun that strikes the face of the Earth for a week
5 times the estimated energy contained in the world's coal reserves
4 times the identified global uranium-238 resources
3 times the estimated energy contained in all the world's fossil fuel reserves
3 times the estimated total energy released by the 2004 Indian Ocean Earthquake
More than 20 teratons of TNT. (20,000,000,000,000 tons)

The amount of energy needed to lift it out is a lot more than that. Most of the gravitational energy of the collapse of the star has escaped in the form of neutrinos during the supernova explosion, and you have to provide that as well to lift something out.
IF we can build something that can withstand the pressure of neutron
star material, getting te required energy can't be difficult, because you
can get lots of energy from dropping stuff on the neutron star.