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.
So 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
Yeah, 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.
Do 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.
You’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.
The 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.
>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...
> 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.
Is it just me who found the technical description and analogy here lacking?
There's nothing that suggests electrons are a cloud. Yes, a "cloud" defines the probability where they can be found, but electron doesn't occupy the cloud.
Electron is always a point, no matter what wave function it has. Therefore, from this perspective space is all empty.
If you invoke path integrals and infinitely many things bubbling in and out of existence, space suddenly fills up. But the author doesn't even mention that.
If you want to understand this stuff, read up Feynman's descriptions & lectures on QED.
If an electron is always a point, how does it have a wave function? Field is the proper term for "cloud", and Quantum Field Theory is an alternative description of the universe, where fields are fundamental, and particles are excitations in the fields.
> Electron is always a point, no matter what wave function it has. Therefore, from this perspective space is all empty.
That depends on what interpretation you're going with. Even with that caveat, I'd be surprised if most physicists would agree with that statement. Electrons are in fact described by the wave function. It's not that the wave function tells us where the electron is, but that the best way of describing the reality of the electron is through its wave function. How and why measurements seem to cause that wave function to collapse to a definite location is different depending on your interpretation of QM.
The electron is both a particle AND a wave. So for practical purposes we must use words like clouds, or regions, or the electron is “spread out”
Neither of the words capture the essence of what is truly going on, afaik.
Language is ambiguous and we are debating between two meanings of empty - nothing there or nothing there, but can be replaced with something else. And we have the added distraction of what nothing means - no physical, permanent “particles” or the abstract empty space.. We can go down the rabbit hole of parsing semantic meanings.
How often do objects interact with our bodies when passing through us? Neutrinos, very rarely. The atoms of an aluminum bat, very commonly. Light? It depends.
Something being "empty" or "full" all depends on spatial and energetic scale.
But visible light can't get through us at all. Does that prove that we aren't empty space? The whole point is that this criterion is incredibly ambiguous.
Depending on the conditions, it is through that neutrinos can pass through even very degenerate matter like that which forms neutron stars. "Empty space" really doesn't mean all that much if the thing that is interacting with it does so weakly.
All the article says is that "empty" isn't enough information.
If "empty" means "I can put electrons in there", then it takes more binding energy to pack more electrons into the same space. If you want to pack more electrons in, you have to squeeze harder.
Example: you can confine an electron to a tiny part of an atom (electrons in inner shells of heavy atoms, for example) but those electrons are very tightly bound (held in by very high ionization energies).
Or the "emptiness" of an atom could be measured using neutral particles, which don't interact with the electrons at all and sail right through as if the electrons were empty space.
For what it's worth this is normal sophomore physics. There's no way to just dismiss it. But there's also no way to claim it's less than a hundred years old.
> For non-quantum objects, this isn’t a problem, as different methods of measuring an object all give you the same answer. Whether you use a measuring stick (like a ruler), high-definition imaging, or a physics-reliant technique like Brownian motion or gravitational settling, you’ll arrive at identical solutions.
Right off the top, it's made clear this author doesn't know what he or she is talking about. From at least the time of de Moivre, around 1740, the problem of estimating an accurate true value from multiple differing measurements was recognized in its own right as a problem. By 1810, Gauss and Laplace had discovered the basics of statistical estimation, the form of the normal distribution, results including the central limit theorem, and regression techniques such as non-linear weighted least squares. Now, almost 200 years later, the problem still exists, and is being worked on in various forms and circumstances.
To give a simple example, take 1000 frames of well-exposed video of a still scene, with constant illumination, and constant exposure settings on the camera. Now try to estimate how many photons, within a constant multiplicative factor, are coming from each point in the scene. Most of the measurements will show a normal distribution, but at the extremes of exposure, something more complex is going on (perhaps to do with sensor non-linearity, censored sampling, or something else). This is one of the basic theoretical problems in HDR imaging, and is an active area research (i.e. unsolved, as of today).
It's very hard to get past that paragraph -- which is the first one in answer to the question "why?".
So, in an atom, how much volume does the electron cloud occupy? It's more than the volume an electron occupies, but, in the upper end, does it occupy all the space from the electron to the nucleus? (And also because it is rotating, that space then occupies all the area surrounding the nucleus as well?)
One on hand, electrons as point particles sure sounds empty enough. On the other hand, the fields fill everything.
But on the gripping hand, you could set the volume of the electron to something ludicrously large, like the volume of a proton, then use the charge distribution of whatever "orbital" to trade that charge for an equivalent amount of proton-volume, as sort of a percentage filled of unit volume ... integrate, and you could get a sense of the density.
That, I think, is about as fair as you could ask for when dealing with point particles that are still smeared around.
Readit News
>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.
https://www.scirp.org/journal/paperinformation.aspx?paperid=...
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...
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.
Try it.
There's nothing that suggests electrons are a cloud. Yes, a "cloud" defines the probability where they can be found, but electron doesn't occupy the cloud.
Electron is always a point, no matter what wave function it has. Therefore, from this perspective space is all empty.
If you invoke path integrals and infinitely many things bubbling in and out of existence, space suddenly fills up. But the author doesn't even mention that.
If you want to understand this stuff, read up Feynman's descriptions & lectures on QED.
Downvote for this article (sorry).
That depends on what interpretation you're going with. Even with that caveat, I'd be surprised if most physicists would agree with that statement. Electrons are in fact described by the wave function. It's not that the wave function tells us where the electron is, but that the best way of describing the reality of the electron is through its wave function. How and why measurements seem to cause that wave function to collapse to a definite location is different depending on your interpretation of QM.
Something being "empty" or "full" all depends on spatial and energetic scale.
If "empty" means "I can put electrons in there", then it takes more binding energy to pack more electrons into the same space. If you want to pack more electrons in, you have to squeeze harder.
Example: you can confine an electron to a tiny part of an atom (electrons in inner shells of heavy atoms, for example) but those electrons are very tightly bound (held in by very high ionization energies).
Or the "emptiness" of an atom could be measured using neutral particles, which don't interact with the electrons at all and sail right through as if the electrons were empty space.
For what it's worth this is normal sophomore physics. There's no way to just dismiss it. But there's also no way to claim it's less than a hundred years old.
Right off the top, it's made clear this author doesn't know what he or she is talking about. From at least the time of de Moivre, around 1740, the problem of estimating an accurate true value from multiple differing measurements was recognized in its own right as a problem. By 1810, Gauss and Laplace had discovered the basics of statistical estimation, the form of the normal distribution, results including the central limit theorem, and regression techniques such as non-linear weighted least squares. Now, almost 200 years later, the problem still exists, and is being worked on in various forms and circumstances.
To give a simple example, take 1000 frames of well-exposed video of a still scene, with constant illumination, and constant exposure settings on the camera. Now try to estimate how many photons, within a constant multiplicative factor, are coming from each point in the scene. Most of the measurements will show a normal distribution, but at the extremes of exposure, something more complex is going on (perhaps to do with sensor non-linearity, censored sampling, or something else). This is one of the basic theoretical problems in HDR imaging, and is an active area research (i.e. unsolved, as of today).
It's very hard to get past that paragraph -- which is the first one in answer to the question "why?".
One on hand, electrons as point particles sure sounds empty enough. On the other hand, the fields fill everything.
But on the gripping hand, you could set the volume of the electron to something ludicrously large, like the volume of a proton, then use the charge distribution of whatever "orbital" to trade that charge for an equivalent amount of proton-volume, as sort of a percentage filled of unit volume ... integrate, and you could get a sense of the density.
That, I think, is about as fair as you could ask for when dealing with point particles that are still smeared around.