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[KittyTac]

The only thing that separates you from the nearest black hole that can absorb your body and erase you from existence down to the atomic level is a thin layer of vacuum only a scant 27,000 light years thick.

I think a black hole can rip your molecules into individual atoms.

IIRC the atoms get crushed further, the gravity overcoming the strong nuclear force between the atomic components and they all get mushed into neutronium. Atleast, that's what neutron stars are made of, we can't observe what a black hole is made of, but I'd imagine it's something similar.

/bracingmyselftogetcorrected

A black hole is not made of anything. It's an infinitely dense, infinitely small point, surrounded by an event horizon, a sphere from which not even light can escape (hence why it's black). Basically what happens if you crush neutronium too hard.

[Reelya]

The only thing that separates you from the nearest black hole that can absorb your body and erase you from existence down to the atomic level is a thin layer of vacuum only a scant 27,000 light years thick.

I think a black hole can rip your molecules into individual atoms.

IIRC the atoms get crushed further, the gravity overcoming the strong nuclear force between the atomic components and they all get mushed into neutronium. Atleast, that's what neutron stars are made of, we can't observe what a black hole is made of, but I'd imagine it's something similar.

/bracingmyselftogetcorrected

A black hole is not made of anything. It's an infinitely dense, infinitely small point, surrounded by an event horizon, a sphere from which not even light can escape (hence why it's black). Basically what happens if you crush neutronium too hard.

However, the time dilation makes exactly specifying what's in a black hole now a bit more complex than that. Technically, the infinitely dense point never exists relative to our outside reality due to infinite time dilation at the event horizon. Black holes are always about to collapse.

You can't say a black hole "is" an "infinitely dense, infinitely small point", it just will be, after an infinite amount of time has passed.

At the event horizon of a black hole, this deformation becomes so strong that there are no paths that lead away from the black hole. ... Due to this effect, known as gravitational time dilation, an object falling into a black hole appears to slow as it approaches the event horizon, taking an infinite time to reach it.

So, we have a bit of a problem here, because relativity also says that from an external perspective it takes infinity time to reach the event horizon. Additionally, the schwarzchild radius for a set mass is linearly proportional to that mass: that means that volume increases as the cube of the mass. You can then reverse engineer the numbers: given any density of matter, including the known universe's density you can work out the maximum possible size of the universe. Because, if it was any bigger than that, it would have enough combined gravitational force to form an event horizon around that space.

What this suggests: the fact that bigger black holes are less dense, and that infalling matter takes infinity time to pass through the even horizon suggests that black holes don't actually grow because matter fell in because that would be a paradox (matter takes infinity time to actually fall in). No, what actually happens is that as matter gets close enough to the event horizon, then the location of the event horizon moves outwards. Because larger black holes are less dense than smaller ones, just moving enough matter near the event horizon is enough to cause the event horizon to move outwards.

[KittyTac]

Welcome to black holes. Breaking your brain since 1916.

[Reelya]

Also to put this out there, it looks like black holes don't even need to touch each other to merge.

Say you have black holes of mass 1 and you define that to have diameter 1. Touch two of them together and you have a mass 2 black hole of diameter 2. Then, touch two of those together and you have a mass 4 black hole of diameter 4.

But now backtrack, take 4 of the mass 1 / diameter 1 black holes, then you can definitely fit them inside a sphere of radius 4 without needing to even touch them together, and now that overall collection of masses has it's own, larger schwarzchild radius and forms a size-4 black hole without any of the masses actually having to have hit each other's event horizon. Which would be impossible anyway, since it takes infinity time to hit an event horizon.

This is what I mean by saying that matter doesn't "fall" into black holes. The event horizon just grows past where you are as the balance of matter changes.

[Yoink]

I remember reading about molecules as a kid, staring real hard at my hand and convincing myself I could see them.

[KittyTac]

I remember reading about molecules as a kid, staring real hard at my hand and convincing myself I could see them.

Same, but with bacteria and atoms.

[FallacyofUrist]

Same, but with bacteria and atoms.

I'm pretty sure I read about researchers training people to detect a single photon with their eyes so, who knows.

[hops]

I have occasional times when I realize that there is nothing between me and the universe except a thin sheath of gas, and start to royally freak out.


At the same time, I have occasional bouts of "jesus christ the wals are closing in, need space need space".

The thin sheath of gas is several times taller than you.












shorty

[Il Palazzo]

This is what I mean by saying that matter doesn't "fall" into black holes. The event horizon just grows past where you are as the balance of matter changes.

It's probably not the most sensible thing to use the Schwarzschild solution for either the infalling matter, the orbiting black holes, or the universe as a whole. I mean, you can do it - as in plug in the numbers - but what does it really tell you then?

[Hanslanda]

Same, but with bacteria and atoms.

I'm pretty sure I read about researchers training people to detect a single photon with their eyes so, who knows.

There's a guy that forms round stones with his bare hands to set the standardized weights and measures who can apparently deliberately abrade and feel the difference of one layer of molecules.

[JoshuaFH]

Same, but with bacteria and atoms.

I'm pretty sure I read about researchers training people to detect a single photon with their eyes so, who knows.

There's a guy that forms round stones with his bare hands to set the standardized weights and measures who can apparently deliberately abrade and feel the difference of one layer of molecules.

I saw that, and apparently he does a pretty good job of it. The bit on TV explained that if the sphere he was crafting were enlarged to the size of the Earth, the highest mountain and the lowest valley would only be a few feet apart, IIRC. Though apparently he doesn't have an apprentice, so this legendary skill dies with him.

I mean, if you're going to define the kilogram or whatever it was with an arbitrary value that requires a perfectly round super sphere, you might as well have it defined by a mystical craftsman who nooone will ever be able to replicate I guess? It's not like it could just be some mathematical constant or something, like the meter is.

[Dunamisdeos]

Because the size of the universe changes, and therefore so does the kilogram :3

At any rate, I recall reading that his goal is to create a sphere so perfect that it weighs exactly one what-we-consider-to-be-a-kilogram down to the molecule, and then we can record that on a permanent basis. The guy can apparently feel the difference in nanometers.

[KittyTac]

Because the size of the universe changes, and therefore so does the kilogram :3

I think that's not true. If the mass and size of objects got larger as the universe expanded, we would not be able to detect the expansion.

[Dunamisdeos]

Eh, I've read articles that say that's why, and other's that don't, but more that say it is. The difference is apparently in micrograms. I'm just repeating things I read, I'm not in on the science of it.

[dragdeler]

-snip-