neutron star

inou2 · Apr 16, 2008

HI my first post here. Been reading this forum for years but i rarely post anywhere, But back on subject, If a thimbleful of neutron star material weighs a hundred million tonnes, what would happen if we brought some back to earth somehow? <div class="Discussion_UserSignature"> </div>

nimbus · Apr 16, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>HI my first post here. Been reading this forum for years but i rarely post anywhere, But back on subject, If a thimbleful of neutron star material weighs a hundred million tonnes, what would happen if we brought some back to earth somehow? Posted by inou2</DIV>I suppose it only weighs that much because of gravity in a neutron star's radius.  Instantly teleported here on Earth where ambient density's not nearly as much as in a neutron star, the thimbleful would probably unpack itself, but I don't know enough about that to guess exactly what that would be like. <div class="Discussion_UserSignature"> </div>

derekmcd · Apr 17, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>HI my first post here. Been reading this forum for years but i rarely post anywhere, But back on subject, If a thimbleful of neutron star material weighs a hundred million tonnes, what would happen if we brought some back to earth somehow? Posted by inou2</DIV>I can't say for sure what would happen, but it's fun to speculate.  First, we have to throw known physics out the window to even allow for something like this to even happen.  Even science fiction has some basis in reality, but I can't think of anything so fantastical as to allow for something like this.   But let's assume... <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /> First thing you have is a thimble full of neutron degenerate matter that probably has enough mass to build a fairly large city.  Once this thimble is released, the first thing that would likely happen is a rapid expansion of free neutrons due to lack of gravity to overcome the degenerate pressure. Neutrons in nature outside of a neutron star do not lump together and floating about by themselves are unstable. This is where things probably start to get ugly.  These free neutrons are probably in an extremely high state of energy and would be moving about quite rapidly.  This, I don't believe, would be the major problem.  The problems start when the highly energized particle start to decay. When a neutron decays, It becomes an electron and proton.  This beta decay is highly radioactive and are how fission reactions occur.  Now we have free neutrons, electrons, and protons randomly slamming into each other creating an uncontrolled nuclear reaction.  Doesn't sound like something we should do. Mind, you... I'm only guessing here.  Maybe someone with a little more expertise could chime in, but i'm probably fairly close  <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

Saiph · Apr 17, 2008

Actually, they won't just unpack automatically, IIRC.  First the lump would have to absorb enough ambient energy to rise up out of the degenerate state, so if you deny the lump that energy...it'll just sit there and weigh a lot

<div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

derekmcd · Apr 17, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Actually, they won't just unpack automatically, IIRC.  First the lump would have to absorb enough ambient energy to rise up out of the degenerate state, so if you deny the lump that energy...it'll just sit there and weigh a lot

Posted by Saiph</DIV>I thought about this a bit before I posted.  I still think there would be some rapid expansion.  I understand that Pauli Exclusion is not a force that is pushing the particle apart.  I also realize that neutrons are neutral and will not have a repulsive force.  I think entropy would be the overriding factor of the expansion of this thimbleful of mass.  I think once this matter would be released, it would expand like any other superheated gas/plasma.If not (and I  could be wrong), our thimble would just burrow its way to the center of the earth and make this discussion boring...<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" />  <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

pyoko · Apr 18, 2008

I am guessing fusion would occur. This would be rather violent. <div class="Discussion_UserSignature"> -pyoko the duck It is by will alone I set my mind in motion. </div>

Saiph · Apr 18, 2008

Sorry, no fusion for you!

As the material is pure neutrons you won't get any fusion.  As a matter of fact, that's a specific property of neutron stars, they don't undergo fusion.  They can't.  Surfaces gases may fuse, but the neutron star itself does not. derek:  Think of degenerate matter as a phase of matter, like ice is the solid phase of water.  It takes energy going into the system to move the matter out of the degenerate state.  It's already at insanely high temperatures at the nuetron star surface.  Even if you remove the vast pressure of the gravitational field...you haven't put any energy into the lump of neutronium.  And the neutronium is going to be far hotter than the surroundings, so it's only going to shed heat, losing energy, making the energy deficit worse.One thing to remember about entropy: It's a statement of overal order/energy in a system.  It doesn't drive anything.  It's an observation of overall behavior of a system.  Entropy increases in any closed system over time.  Entropy increases by the objects moving to the lowest possible energy state, which in a gravitational system is compacted, and compressed (lower potential energy that way) and in a thermodynamic system it's cold (less motion).  Both tendencies only encourage the neutronium to remain compacted. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

pyoko · Apr 18, 2008

Fusion does not occur in neutron matter in a neutron star. It will if magically teleported to the surface of Earth, as the expansion will have enough energy to fuse atoms. <div class="Discussion_UserSignature"> -pyoko the duck It is by will alone I set my mind in motion. </div>

Saiph · Apr 18, 2008

sorry, still, "No fusion for you!"

First, it won't expand, see my previous posts.The material is now in a much colder environment with basically no pressure applied to it. Now, it's hot, so that alone will really mess things up (it's 25,000+ K).  But it won't start any fusion.  The atmosphere is far to rarified, the temperature spike from the material would only make it more so, and there is no amount of readily fusile material in the air.  Theres nitrogen and oxygen for the most part, but to fuse that requires temperatures and pressures far in excess of what a hot rock (even at 25,000 K) can produce.  The temperature has to exceed millions of degrees kelvin, with a monumental pressure that the earth's atmosphere can't provide, and the neutronium has no mechanism to produce.The massive dump of heat radiated into the air will certainly make things interesting.  you've go the mass of a mountain in something the size of a golf ball.  At 25,000K it has a luminosity of...lets see, L=4pi*sigma*R^2*T^4sigma=5.67×10−8 W·m-2·K-4r=0.02mt=25,000Kgiving L=1.1x10^8 Watts.Nasty, very nasty.  And I've no idea how much heat is actually in the lump, as I don't know the specific heat of neutronium... <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Saiph · Apr 19, 2008

so, the golf ball sized lump radiates at 1.1 x10^8 watts, which is joules per second.Lets try and put this in more useful, or at least familiar terms.Water requires 334 J/g to turn from ice to waterWater requires  2260 J/g to turn from water to steam.Water requires 4.184 J/g to  raise 1 degree celsius., raise it 100 degrees and thats 418.4 J/g to go from 0 to 100 C.So, to melt ice, and turn into steam requires 3012.4 J/g...lets make that an even 3,000 J/g.Now, that lump of neutronium is putting out 1.1x10^8 J/s, so that means it can boil 36,666 grams of ice per second... or 36.6 Kilograms.Hmm, doesn't quite seem large enough, wonder if I dropped a decimal somewhere.  <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

pyoko · Apr 19, 2008

I haven't had enough sleep for those numbers, but the term "hydrogen bomb" comes to mind. The golf ball is not going to need the nitrogen and what not in the air to fuel fusion. P.S. Your numbers are 'magic'. I will try to formulate a better answer when my evil side arrives. <div class="Discussion_UserSignature"> -pyoko the duck It is by will alone I set my mind in motion. </div>

Saiph · Apr 19, 2008

Hydrogen bomb: Ahh yes, the fusion bombs.  Those are where a core of heavy hydrogen isotopes are subjected to millions of degrees kelvin, and insane pressures created by the core of a fission bomb during it's explosion...Sadly, it's a far cry short of atmospheric pressure, and 25,000 Kelvin.  Especially when the forces involved will actually work to decrease the pressure, as the hot air is expelled away from the neutronium, diffusing away. Also, there's nothing "magic" about my numbers.  I may be off on my temperature for the surface of a neutron star (feel free to correct me) but even if I'm off by, say a factor of 10, that doesn't change things much. Now, if anybody wants to contemplate how this coulld explode dangerously...if you did manage to pump enough energy into it to boost it out of the degenerate state, then  you'd have all those millions of tons of neutrons now "free".  And "free" neutrons don't live very long, they've got a short half-life (about 10 minutes)...and all those neutron decaying we could safely say, "would be a bad thing."  <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

derekmcd · Apr 22, 2008

Ok, Saiph... what you said makes sense about expansion.  I didn't take into account the strong force binding the neutrons together (hence my assumption of free neutrons and rapid beta decay).  There might be a little bounce to it if the neutron are so close the strong force becomes repulsive and when pulled from it's gravity well, the 'neutronium' would find it's natural balance of 2 or so femtometers between the individual neutrons.So my revised hypothesis would be that you would have a thimble sized ball of material with about the same density of an atomic nucleus falling to (and through) the earth's core like a lead ball being dropped into water. (I like my original statement better... more destructive).And definitely no fusion, although I mentioned the possibility fission... but even that would seem unlikely.  I still say beta decay is inevitable, though, albeit, harmlessly at the earth's core.  <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

Saiph · Apr 22, 2008

Hmm... Now that I think about it more, you are right that there will be some beta decay, as the nuetrons expereince the quantum tunneling phenomena and find themselves free.  It certainly won't be pleasant to be around what I'd imagine to be a highly radioactive source.That alone could "melt" the surroundings, perhaps rivaling the 25,000 K temperature (anybody else have a good figure for neutron star surface temperatures?) <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

derekmcd · Apr 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Hmm... Now that I think about it more, you are right that there will be some beta decay, as the nuetrons expereince the quantum tunneling phenomena and find themselves free.  It certainly won't be pleasant to be around what I'd imagine to be a highly radioactive source.That alone could "melt" the surroundings, perhaps rivaling the 25,000 K temperature (anybody else have a good figure for neutron star surface temperatures?) Posted by Saiph</DIV> I think the degenerate matter comes from the interior and not the surface.  I also think that neutron stars cool quite quickly and their temperatures will widely vary depending on their age.  <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

Saiph · Apr 22, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> I think the degenerate matter comes from the interior and not the surface.  I also think that neutron stars cool quite quickly and their temperatures will widely vary depending on their age.  Posted by derekmcd</DIV> Actually, the degenerate matter comes from the surface, and th ecore.  It's only the "atmosphere" of highly compacted hydrogen and helium gases that can settle on the neutron star that aren't degenerate solids.Also, they cool slowly.  They form in the core of a supermassvie star, the core of a supernova, so they start insanely hot.  Throw in their small size (less than the moon, though they weight over 2x the sun!), and they can't radiate that immense amount of heat quickly.  Even with a 13 billion year spread, they are all pretty hot.  I think I'm lowballing the temperature estimate at 25,000 K.  I'm pretty sure that's the characteristic temperature of much cooler (and larger) white dwarf stars. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

derekmcd · Apr 23, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> Actually, the degenerate matter comes from the surface, and th ecore.  It's only the "atmosphere" of highly compacted hydrogen and helium gases that can settle on the neutron star that aren't degenerate solids.Also, they cool slowly.  They form in the core of a supermassvie star, the core of a supernova, so they start insanely hot.  Throw in their small size (less than the moon, though they weight over 2x the sun!), and they can't radiate that immense amount of heat quickly.  Even with a 13 billion year spread, they are all pretty hot.  I think I'm lowballing the temperature estimate at 25,000 K.  I'm pretty sure that's the characteristic temperature of much cooler (and larger) white dwarf stars. Posted by Saiph</DIV> I might just be arguing semantics here, but my understanding is that the surface of the crust is not degenerate because there is not enough pressure.  I've read it is mainly iron.  It's not until you get below the surface of the crust (albeit, still in the crust) that the matter becomes degenerate in phases.  The gravitational gradients are quite extreme here.  The difference between the surface and 500 or so meters deep makes quite a difference.  I've read the crust is anywhere for 1-2 km thick and is not uniform.  Below the crust is still anyone's guess. (the surface probably is, too... just not enough info).I did underestimate how rapidly neutron stars cool off.  When they are created, they will have temperatures in excess of 100 billion K.  They cool off to about some 500,000 K in only 1000 years, so it would be unlikely we would catch one whille it's cooling off.  At that point, they do cool off very slowly.As for their size, they are far smaller than the moon.  Estimated at about 10-30 km in diameter depending on their mass. (the more mass, the smaller they are).  <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

MeteorWayne · Apr 23, 2008

It's really just such an amazing concept...a city sized "object" with the mass of a star. Makes my head all wobbly...  <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

derekmcd · Apr 23, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>It's really just such an amazing concept...a city sized "object" with the mass of a star. Makes my head all wobbly...  Posted by MeteorWayne</DIV> No doubt about it.  I imagine many physicists have had their faces look like your avatar after trying to figure them out so dummies like my avatar can talk about them.(btw, King Crimson is awesome... so many killer artists that have contributed to that body of work).  <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

MeteorWayne · Apr 24, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> No doubt about it.  I imagine many physicists have had their faces look like your avatar after trying to figure them out so dummies like my avatar can talk about them.(btw, King Crimson is awesome... so many killer artists that have contributed to that body of work).  Posted by derekmcd</DIV>I heard "Lucky Man" on the radio yesterday, and it made me want to play the Court of the Crimson King...but I can't cause all the windows are open, and the only way to play that is LOUD!!!Sunday it's supposed to get cloudy and cooler, so the windows will be closed...<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-cool.gif" border="0" alt="Cool" title="Cool" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

derekmcd · May 1, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>It's really just such an amazing concept...a city sized "object" with the mass of a star. Makes my head all wobbly...  Posted by MeteorWayne</DIV>And if it wasn't wobbly enough, here's this...http://www.space.com/scienceastronomy/080430-neutron-star.html "The neutron star produces about 7 to 10 bursts per day. These explosions release more energy in 100 seconds than our sun radiates in an entire week. The energy is equivalent to 100 hydrogen bombs exploding simultaneously over each postage-stamp-size patch of the dying star's surface." <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

pradipta · May 8, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>HI my first post here. Been reading this forum for years but i rarely post anywhere, But back on subject, If a thimbleful of neutron star material weighs a hundred million tonnes, what would happen if we brought some back to earth somehow? Posted by inou2</DIV> SUN is the only star of solar system as well as the universe. Visit http://www.spacemirrormystery.com to know the logic and original truth.    <div class="Discussion_UserSignature"> pradipta </div>

eburacum45 · May 8, 2008

I can't agree that the lump of neutron star material would just sit there, Saiph; everything I have heard about this subject suggests that its internal pressure would cause it to explode violently. The interior of a neutron star is inder immense pressure- which causes the material to become degenerate; this degeneracy pressure would make the material explode. I can't see any way to keep the material together as a coherent lump, even if it drops straight into the Earth. The lump of material would simply expand inside the Earth, as if the material of the Earth were thin air. This would probably manifest itself as a huge underground explosion. <div class="Discussion_UserSignature"> ---------------------------------------------------------------http://orionsarm.com http://thestarlark.blogspot.com/ </div>

eburacum45 · May 8, 2008

In this post at physicsforums Chronos talks about this subject; http://www.physicsforums.com/showpost.php?p=420210&postcount=11

To condense matter to the state that exists in a neutron star, you must overcome the neutron degeneracy pressure [for white dwarfs, it is the electron degeneracy pressure]. The minimum amount of matter required to generate a gravitational field sufficiently powerful to reach the neutron degeneracy pressure is about 1.4 solar masses. The minimum mass required to produce a white dwarf is about .67 solar masses. Anything less than .67 solar mass does not have enough gravity to self collapse into a condensed matter state. In other words, the smallest stable chunk of neutron star matter that can exist is 1.4 solar masses. It may be theoretically possible to compress a smaller quantity of matter to these states using external force, but, it would not be stable. Even if you crushed a small amout of matter down to a black hole, it would rapidly radiate mass away and explode. Degenerate matter also radiates intensely and would go poof as well.

I'm not sure that black holes and neutron star matter are directly comparable, but it does look as if an isolated lump of neutronium would explode.  <div class="Discussion_UserSignature"> ---------------------------------------------------------------http://orionsarm.com http://thestarlark.blogspot.com/ </div>

Saiph · May 9, 2008

Should be "stable" except for escaping neutrons (via tunneling effects).   That would be nasty...and offhand I don't know how significant this decay would be.  It could be pretty quick...The reason is, as I stated above, the fact that it's in a "degenerate" state of matter.  It takes energy to get out of that state...  Once it's there, it isn't kept there by the pressure exerted on it.  At least, that's my understanding of the subject.  <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

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