Mr. Sagan (I think) once warned that neutronium/strange matter/neutron star guts was so dense (and therefore heavy) that if you were to drop a teaspoon of the stuff from about chest height it would fall straight through the earth. Or something like that.
Now this is good to know because I was kicking around getting my kids a do-it-yourself neutronium kit for Christmas. But they’re really careless and I could just see having dozens of holes in the bottom of my house that go clean through to…ok, the questions:
really?
would that generate a lot of heat (enough to melt stuff)? Or would it be akin to poking a hole in the ground with a stick, only with much less resistance?
how fast would it be going by the time it hit the center of the planet? How long would it take to get there?
Is that stuff stable outside of a neutron star, or would the lower pressures of space allow it to puff up some. How much would it puff?
If it doesn’t puff in a vacuum, and two neutron stars collided, could there be big hunks of neutron star whizzing around space just looking for a planet to crash into?
Assuming that it falls freely (i.e. that the Earth is so flimsy that soil, rock and iron core provide no resistance to the neutronium), it would take 42 minutes to reach the center of the Earth.
Yeah, it would not be stable. The gravity provides force that overcomes neutron degeneracy pressure, take it out of the star and it would puff right up. Do not get your kids that diy neutronium kit, those things are very poorly made and the instructions are book-translated from Tagalog or something. If they screw up, they will destroy the earth, then where will we go?
I expect that it would ‘expand’ by spitting out subatomic particles at very high speeds until it was all gone. A chunk of neutronium outside a gravity well is essentially an atomic nucleus with far, far too many neutrons, and would act like one. Not so much an expansion as an explosion. You wouldn’t want to be anywhere near it.
Some googling got me this article, which claims that besides the “teaspoon of neutronium” expanding with immense force due to the sudden lack of pressure, the neutron decay would put out a huge amount of energy.
And googling gravity + teaspoon + neutronium gets me multiple results from the SDMB; people seem to like the concept here.
According to wikipedia, a teaspoon of neutronium would have a mass of a couple billion tons. A lot, but not a ridiculous amount. And we think of it as a lump of stuff, but without the normal electromagnetic properties of non-degenerate mundane matter, there is not way for it to for any kind of internal structure, so it tends to be called a gas. It is not clear that it would even penetrate the Earth’s solid surface, other than by an enormous explosion that would probably reduce the earth itself to a dust cloud.
Those home neutronium kits are pretty hazardous. They use some kind of arcane degenerator field to form the neutronium and confine and stabilize it. Most people experience a problem when they turn the field off and the energy stored in it gets released. As I recall, there is a way to hook up eight D batteries so you can safely unplug the thing, and they will hold the field for about 17 minutes before they run out. You can rig up a plug that will work in your car, so if you actually manage to throw that much stuff into the thing, enough to make a pinpoint size droplet, you will at least be able to take the unit out in the desert or something so that your own neighborhood does not get cratered when the field shuts off.
It is pretty amazing that you can convert your household clutter into neutronium for such a small energy input. I think we need to make sure there are not any crazy terrorists getting their hands on one of these. Sane terrorists would be fine, though.
That’s an extremely interesting question that I hadn’t thought of. Could “neutronium”, if it could possibly be stable, essentially pass through normal matter with minimal interaction?
Let’s say for the sake of discussion that we have the equivalent of neutronium: something that dense but stable; and I’ll specify further that it attracts enough electrons to interact conventionally with normal matter. Say, strange matter clumps with just enough charge that they behave like super-heavy atoms.
I think the first thing that would happen when your billion-tonne teaspoon-full hit the ground would be that the ground would have to get out of the way FAST. So much force would be concentrated in so small an area that the ground would offer essentially zero resistance. In loose soil or porous rock like sandstone that would scarcely matter; but as soon as it hit solid rock the rock would be blasted out the way fast enough to vaporize it. So what you’d probably get is a small local earthquake and a geyser of plasma shooting out of the ground until it got deep enough.
What would happen if you could release the pressure on a teaspoon of neutronium slowly? What element would it have decayed to by the time it got to room temp and 1 atmosphere of pressure?
Release it slowly, and you’ll definitely end up with mostly iron, plus a few other elements in that vicinity. Release it quickly, and you’ll probably end up with the same, but it’s harder to predict.
Let’s stay real here. But this state of matter is that of unobtainium, right? Nary an electron in the real world, when this thought experiment trouble starts?
“A reactor vessel of a typical nuclear power plant (PWR) endures in 40 years (32 full reactor years) of operation approximately 3.5×1019 n/cm² (E>1MeV).” Wiki “neutron flux.”
But it leads off with this, which I don’t understand, how the OP’s neutron star scenario relates, because supernova is after the fun starts.
Neutron flux in asymptotic giant branch stars and in supernova is responsible for most of the natural nucleosynthesis producing elements heavier than iron. In stars there is a relatively low neutron flux on the order of 105 to 1011 neutrons per cm2 per second, resulting in nucleosynthesis by the s-process (slow-neutron-capture-process). By contrast, after a core-collapse supernova, there is an extremely high neutron flux, on the order of 1022 neutrons per cm2 per second, resulting in nucleosynthesis by the r-process (rapid-neutron-capture-process).
Atmospheric neutron flux, apparently from thunderstorms, can reach levels of 3•102 to 5•102 neutrons per cm2 per sec.[3]
(That atmosphere part is intriguing as well.)
But this state of matter is that of unobtainium, right? Nary an electron in the real world, when this thought experiment trouble starts?