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Empty space, by definition, is space that can be filled by something. So how closely can atoms pack together? A neutron star has a density of 10^17 kg/m^3, wher
by kylec 6y ago
Empty space, by definition, is space that can be filled by something. So how closely can atoms pack together? A neutron star has a density of 10^17 kg/m^3, whereas the typical human being is about 10^3 kg/m^3. I could fit the matter of trillions more human beings in the same space I'm taking up now. So yeah, I think there's some empty space in me.
- themodelplumber 6y agoSo the author is saying fields are already filling things up, right? To compare this to the "we can pack them atoms tighter" model seems to be confusing the author's model with another, separate mental model, one in which we can fill up more. But the author's model says we're full. Full of this field stuff. Not so? IANAS
- Retric 6y agoYou’re not filled with fields or those fields would block neutrinos. Instead we can shoot them though the earth and detect them just fine on the other side. Fields represent possible locations, not actual locations.
- not2b 6y agoFor anything that responds to the electromagnetic force, you're filled with fields. For something that responds only to the weak force, you're almost entirely empty space.
- Retric 6y agoIf that’s how you want to look at it, everything responds to gravity. But, that’s not what people mean when they say space is filled.
- mannykannot 6y agoIn the English-language usage I grew up with, 'occupied' means that there is something there, while 'filled' means occupied to the point where nothing more can be added. The former does not imply the latter. In this usage, space itself (the 'empty' space of the article's title) is implicitly not something. This usage may seem to be an accidental issue of language, resulting from an incomplete understanding of physics, but a lot of metaphysics seems to reach the point of hanging on such definitions. One may, of course, agree with both of the points of view expressed in this paragraph.
- lopmotr 6y agoThis whole idea of empty space within atoms is just nonsense using English grammar as a substitute for physics. It's a meaningless statement either way until you define the terms specifically enough. And by doing that, you can choose whatever answer you want. "occupied to the point where nothing more can be added" isn't specific enough because you can still add a lot of photons to a "filled" glass of water, so that means it's not filled by that definition even though it is by common sense. It just shows the irrelevance of everyday words and concepts at the subatomic scale. Even a neutron star is practically invisible to neutrinos which can easily pass through it despite it's being "filled" with neutrons.
- mirimir 6y agoWell, that space is filled, but only because of quantum interactions, and not because it's empty.
- stephen_g 6y agoIt’s abstract, but we experience this kind of issue with language lot. Think of a box that doesn’t have any objects in it. It’s empty, right? But if it’s sitting on the table in front of you it’s probably full of air. So in one respect it’s completely empty but in another it’s totally full.
- amelius 6y agoAnd then there are those who say that space is an emergent property, e.g. https://www.scirp.org/journal/paperinformation.aspx?paperid=88041 https://www.scirp.org/journal/paperinformation.aspx?paperid=...
- mirimir 6y agoYeah, they're probability distributions, not fields. So electrons, protons and neutrons are still tiny, even though their positions are uncertain. And so atoms are still mostly empty space.
- dwaltrip 6y agoI believe there is non-zero vacuum energy. So "something" is going on, whether it be virtual particles popping in and out of existence, even in "empty space". Granted, I don't really understand the details of what this means, but that's what I remember of the current science.
- mirimir 6y agoYes, vacuum energy. But that's still probability distributions, and so almost all of the vacuum is empty at any given time. Most physicists would likely say that there's no point trying to visualize this stuff in mundane terms. Or at least, that's what they were saying the last time I took a physics course.
- praptak 6y agoModeling electrons as tiny objects that have probability distributions has a weakness. There is no sensible value to assign to the 'tiny'. I mean there is no experiment to determine the 'size' of the electron.
- mirimir 6y agoOK, not a physicist. But what about this? https://en.wikipedia.org/wiki/Classical_electron_radius https://en.wikipedia.org/wiki/Classical_electron_radius
- praptak 6y agoCheck all the disclaimers on that concept, in particular "Attempts to model the electron as a non-point particle have been described as ill-conceived and counter-pedagogic"
- toohotatopic 6y agoDo those fields extend into infinity or is there a boundary that the electrons don't cross? >If you took an atomic nucleus and bound only one electron to it, you would see the following 10 probability clouds for each electron, where these 10 diagrams correspond to the electron occupying each of the 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d and 4f orbitals, respectively. The electron is never located in one specific place at one particular time, but rather exists in a cloud-like or fog-like state, spread throughout a volume of space representing the entire atom. If there is no boundary, then the universe itself would be full by that field definition because every electron would be at any point by a very small probability.
- bouncycastle 6y agoYou'll also develop a gravitational field and maybe things will start orbiting you!
- erwinh 6y agoyeah but are you still human then? It's like white space in a photograph or painting, it's part of the composition
- GoToRO 6y agoDo atoms still remain atoms in a neutron star? don't they collapse to a soup of subatomic particles? serious question.
- mirimir 6y agoNope, there are no atoms. Except at the surface, I suppose.
- db48x 6y agoThe core of a neutron star is 100% neutrons (or perhaps a quark-gluon plasma where no individual neutrons are distinguishable). All the electrons and protons have been crushed together (by the extreme gravity) until they merge and form neutrons. As you get further away from the core, you find more and more protons and electrons, but still no atoms. The surface layer of the star has distinct atomic nuclei, but since the surface temperature is so hot (600,000K) they are not neutral atoms; the electrons are not bound to the nuclei. The density at the surface is still about a thousand times higher than the density of water or stone.
- kleiba 6y agoI could fit the matter of trillions more human beings in the same space I'm taking up now. Try it.
- kleiba 6y agoNote to self: stop making non-obviously subtle posts on HN, they always get downvoted.
- coldtea 6y ago>Empty space, by definition, is space that can be filled by something. Is it? I'd say empty space is empty space whether it can be filled or not. If the universe was just 2 plates N meters apart that was impossible to move any closer (e.g. because of opposite forces, like with magnets which work fine in a vacuum), the space between them would still make sense to call empty...
- tomxor 6y ago> Is it? I'd say empty space is empty space whether it can be filled or not. Though technically correct when sticking to matter, it feels so wrong because of how it encourages inapplicable intuitions from the macroscopic world. "We are mostly empty space" is used as trivia, with an implicit exclamation mark suggesting it is astonishing and significant, but it is intentionally incomplete and lacks context - the whole picture shows something far more substantial that has nothing to do with our macroscopic intuitions.
- edem 6y agoThis comment made my day, thanks!
- omgwtf1000 6y agoYou can’t trust atoms. They make up everything.