# What is an Electron? Radius, Substance, Quarks & More

• Jonny_trigonometry
In summary, the electron does not have a radius in the classical sense and is considered fundamental. It is not made of three quarks and is described by a wavefunction. The concept of size is tricky in quantum mechanics and particles do not have distinct boundaries. However, the electron is still considered small due to its highly localized probability distribution. There is no obvious microscopic composition of the electron.
Jonny_trigonometry
Does it have a radius or not? If yes, then what is it? If no, then why does it (seemingly) not curve space-time to the point where it's discontinuous at the electron's center (an infinate potential)? If the answer isn't a yes or no, what is the probability distribution of radii as a function of radial distance? What is the substance that makes up the electron? Is it a group of matter waves bounded by one unit of charge? if it's made of three quarks, how does that work? what forces hold the quarks together, do they have charge or mass? How much empty space is in the electron, if any? If it's a point, is it infinately dense? if it's infinately dense, wouldn't it have infinate mass, and infinate gravity? How does the standard model make such a daft claim that the electron is a point?

Jonny_trigonometry said:
Does it have a radius or not?
Not in the classical sense, no. There is no concept of precise size in quantum mechanics.
If no, then why does it (seemingly) not curve space-time to the point where it's discontinuous at the electron's center (an infinate potential)?
It doesn't have zero size, either. There is no concept of precise size in quantum mechanics.
What is the substance that makes up the electron?
The electron is fundamental.
Is it a group of matter waves bounded by one unit of charge?
I have no idea what this even means, so I guess the answer is no.
if it's made of three quarks, how does that work?
An electron is not made of three quarks. An electron is fundamental.
what forces hold the quarks together, do they have charge or mass?
The strong force. They have both charge and mass.
How much empty space is in the electron, if any?
There is no concept of precise size in quantum mechanics.
How does the standard model make such a daft claim that the electron is a point?
It generally doesn't. The electron is described by a wavefunction, which can be used to find a probability distribution for its detection or interaction.

- Warren

Classical Radius of Electron

Obviously, this isn't a direct measurement, nor is such a thing likely to be possible, but I'd guess this is about the best answer you're going to get that actually gives you a number. At least this will dispel your notion that the electron is thought of as a point particle.

I find all this confusing as well.

If there is no concept of precise size in QM then why do we think of electrons as being very small? Or does non-locality mean that we don't? If electrons are fundamental then would it correct to say that electrons are made out electrons? Did all the electrons in existence emerge fully formed from the initial singularity? This seems to be implied but seems to make no sense.

thats interesting lose your name, I've never ran acroos anything like this before.

Is there really no concept of size in qm? what about the Bohr radius? is that not a size, and won't it usually stay the same? Do you mean that particles have no size? or do you mean that we can't make a precise enough measurement of a particle's size? I understand that the uncertainty principle puts limitations on the things we can know about particles, but it doesn't make the idea of size invalid. Can't size be a sharp observable, while momentum and/or location are fuzzy? Actually that last question just doesn't make sense to me, I never thought the uncertainty principle applied to the size of a particle.

Jonny_trigonometry said:
Is there really no concept of size in qm?
You can make statements like "there is a probability x that a particle will be detected inside some volume V," but that's about as close as you can get to the concept of size. Particles do not have distinct boundaries in quantum mechanics, because quantum mechanics represents particles with wavefunctions, and wavefunctions do not (generally) have sharp boundaries.
The Bohr radius has units of length, but it cannot be interpreted physically as the actual size of anything.
Do you mean that particles have no size?
As I said, the concept of size is tricky in quantum mechanics. There is no "size" operator. The best you can do is to draw a map showing the probability of detecting the particle in each volume unit in space, and then declaring that the "size" of the particle is the volume in which there's a 90% of detecting it. But, therein lies the rub: should you consider the volume in which there's a 90% chance to detect it? Or a 99% chance? Or a 99.9% chance? There's no "definition" of size.
or do you mean that we can't make a precise enough measurement of a particle's size?
We can't, but that's because particles just don't really have "sizes" in quantum mechanics. They don't have sharp edges.
Can't size be a sharp observable, while momentum and/or location are fuzzy?
Location and size are intimately tied together. If location is a "fuzzy" variable, size must be, also.
I never thought the uncertainty principle applied to the size of a particle.
It doesn't, directly. The uncertainty principle results mathematically from the failure of two observables to commute. Since there is no observable for size, there's no uncertainty relation for it, either.

- Warren

When you have many particles, as in a macroscopic object, there is a certain volume inside of which all these particles are extremely likely to be found. This is the everyday notion of size. For a single fundamental particle like an electron, the probability distribution is much more smeared out, and there are no sharply defined boundaries. Still, it is very localized, with a vanishingly small chance of finding it a few cm away, so we can still safely consider it small. Like many macroscopic concepts, there is no obvious microscopic correlate of size.

Last edited:
ok, the size is indeterminate. What about the composition? what is it made of?

if you say matter and charge, then is charge evenly distributed (or embeded) in the mass?

what is meant by fundamental? it can't be cut in half? How can it not be cut in half, and at the same time, be the composition of two different things (mass and charge)? As far as I understand, something that is the composition of two things is not fundamental. Are matter waves not only composed of mass, but also charge? Is the matter wave not just the thing that causes the observation of mass, but also the observation of charge? Keep in mind, wave functions are all based on matter waves, those waves are what the wave functions describe, one such arrangement of matter waves (described by the wave functions) happens to be an electron... So I guess my main question is, in the invention of matter waves, were they given the property of both mass and charge, or just mass?

A wise man once said, re: quantum mechanics:

"Do not keep saying to yourself, if you can possibly avoid it, 'But how can it be like that?' because you will get 'down the drain' into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that."

Sounds like you're headed down that alley.

Jonny_trigonometry said:
what is meant by fundamental? it can't be cut in half? How can it not be cut in half, and at the same time, be the composition of two different things (mass and charge)?
An apple is both red and round. Can you cut an apple into two pieces, one red and one round?

- Warren

Hmm. I see what you mean but apples are not usually considered fundamental. To say that something is fundamental means, to me, that it cannot have parts. A thing that has no parts cannot have extension according to Leibnitz. If electrons are fundamental and Leibnitz was right then perhaps it's to be expected that their extension is indeterminate.

Infidel - I've seen that quote before but can't remember who said it. Can you remember where it comes from?

One very naive question. If an electron has a 50% chance of occupying a particluar volume of space does this mean that 50% of its mass and charge is somewhere else? Or does it have no mass and charge when it's not in that position? Or is this not a sensible question?

thats a great question... I think. But then again, I'm headed down an alley of some sort, so don't take my support seriously.

back to my question that hasen't been answered yet:

So I guess my main question is, in the invention of matter waves, were they given the property of both mass and charge, or just mass?

I understand what you mean Chroot. Suppose I built a couple of identical miniature houses out of legos, in that case, the smallest and most fundamental unit of "lego house" is one of the entire houses and nothing less, but that shouldn't stop our understanding of what the little houses are made from. We most definitely shouldn't make a rash statement like "lego houses are indivisible," does that mean that "lego houses" existed during the big bang?

Here's a weird concept: what if at the center of every particle, there is an extremely large and possibly infinate potential (because it's a point, and doesn't have a surface to touch, so if two electrons get close enough, they can push each other away with the force of a supernova for example, because the coulomb force is inversly proportional to the square of the distance between two point charges). And this potential is a multiply connected space with the big bang. All black holes are multiply connected to the big bang... all particles too. All particles are like tiny windows to the big bang, but the size of the windows are proportional to the energy of the particle (it's momentum). Somehow these tiny windows can coellece into a black hole, which is a much bigger window. Perhaps a black hole is like a huge Bose_Einstienien condensate and behaves just like a particle, but on a maco scale... So all particles are visible because light quanta are too big to fall into their tiny singularities, so the photons are able to bounce off, but not from a black hole, because it's singularity is much bigger. So if all matter is actually just multiply connected spaces to the big bang, then matter itself is imaginary (just in our heads) and the only thing that exists is space, all tied in knots and flowing through and within itself like a giant mobius strip. That would mean that the big bang is continuously occurring, and we only perceived it as an instant because our observable universe that we are familier with today has been moving along with us the whole time (it along with us, has we passed through the point of big bang) so it looks like it was an event that occurred once in the past.

Jonny_trigonometry said:
I understand what you mean Chroot.
I simply mean that mass and charge are not "parts" of the electron, they are characteristics. That an object has more than one characteristic does not make it composite, at least not in the physical sense.
And this potential is a multiply connected space with the big bang. All black holes are multiply connected to the big bang... all particles too.
This doesn't make the slightest bit of sense to me (you are perhaps misusing terms like 'multiply connected" and "potential"), and frankly this sort of speculation is not permitted on this site.

- Warren

Not just photons can move through the multiply connected space at the center of a black hole, but also matter, as long as the singularity radius is larger than the average radius of any particle. The influx of energy being pulled by central forces towards the singularity must be equal to or greater than the uniform energy-density in the big bang. In other words, the "pressure" (or energy-density) at the edge of the radius (event horizon) of any particle can't be less than the energy-density of the big bang or else the pressure of the big bang would push it's way through every particle, and all particles would behave the opposite way (negative would be positive). Pressure is related to the area of the singularity (average radius), because it's in units of force per unit area. So if a small enough area (approaching a point in size) is defined as the area of the singularity (or, area of the open window to the big bang), then any amount of energy distributed on this area can equal or exceed the pressure in the big bang.

Speculation is the reason for epistomology.

I may not arrange words in the way you like, but I just want to communicate this idea to other people. If it only makes sense to me, is it because I'm the only one willing to entertain this thought? I guess I'm special.

How can I better explain this idea... I've already explained that when two particles get close enough to each other, their electric field energy-density can seemingly have no limit if they have no radii. right?

So, using general relativity, (which states that the curvature of space-time is dependant on the amount of energy present per unit volume) then if there exists an infinate energy-density, space-time will be discontinuous (it will be curved so much that it's in a state that we define as a "singularity").

note: particles must have radii, at least a probability distribution of possible radii, and the average radius must be small enough to produce black hole like effects (an infinate potential energy isn't needed, but a very large one is needed).

(keep in mind, I haven't taken any classes on cosmology or general relativity, so I'm not sure if I'm using these words the way cannonical physicists use them (all I know is that somehow a black hole produces a singularity without using an infinate amount of energy), please do me a favor and see these words the way I'm using them and not the way they are exactly defined)

Here's the big jump I make, and is why this is a weird concept: I define this "singularity" as being "multiply connected" to the "singularity" at the big bang. I'm viewing the big bang as kind of a "reverse black hole" (or, a black hole that is viewed backward in time), so in that sense, it does have a "singularity" from which there is an outflux of energy, and at the center, there exists a constant energy-density. This energy density must be equal to or less than the maximum energy-density in the center of every known particle and "macro particle" (if we want to define all particles as multiply connected to the big bang). Viewing things this way, we know that every particle has a total potential energy (from it's mass, charge, momentum, spin, distance from a central force, etc.), so their radius must then correspond to an area that allows that specific particle's energy to be distributed (over the area in a cross-section of in a mannor that equals or excedes the pressure in the big bang. perhaps photons are the only particles that have the property where the two pressures are equal, and somehow because of this they don't have mass.

Jonny trigonometry said:
note: particles must have radii, at least a probability distribution of possible radii, and the average radius must be small enough to produce black hole like effects (an infinate potential energy isn't needed, but a very large one is needed).

Particle probability distributions do not have a well-defined radius. Where do you strike a radius in a bell curve?

well, the best I can do to bridge the gap you see is say that it's not a point and it doesn't have a radius. It's somewhere in between a point and sphere. due to the wave-particle duality of nature, so I simply regard this distribution as the overall radius.

On what basis would you call an electron spherical? The shape of the orbitals described by the wave functions is only spherical at 1s, and even then cannot be said to represent the shape of any corporeal object. We just don't have any idea what it would look like if we could see it. The only hypothesis I know of that even attempts to describe any 'shape' of fundamental particles is string theory, which says they are extended extremely short distances in one dimension. It should be noted that a "string" has no radius.

lets not get hung up on this whole radius thing. We have to accept that it's not there and it is at the same time, just like schrodingers cat has to be both dead and alive at the same time. Thats not even what I'm mainly concerned about, I should have started the thread with the "wierd concept" that I've already written about earlier in this thread.

Chroot, so you're answer is that matter waves are made from mass and charge. That charge is distributed in mass and with one, you will always have the other (otherwise you could cut an apple into one half round and the other red). Ok, thank you. So that means that matter waves are repelled by each other because they are made from negative charges too, not just mass. So the only way they would attract each other is by magnetic forces (if two wave-packets of matter waves are traveling parallel to each other, they will be attracted to each other). All matter is flying away from the big bang, so it's all reletively traveling in parallel paths in local neighborhoods (just like the sun's rays are relevitely parallel at the surface of the earth). Parallel moving like charges attract, and maybe that's why gravity pulls mass together. Since matter waves have both mass and charge, we have to come up with some other reason why gravity emerges.

the main idea I'm trying to bring is the idea of thinking that all particles are "windows" to the big bang, albeit they are windows with fuzzy edges. but fuzzy or not doesn't matter at all, the name of this thread is "what is an electron" not "what is the radius of an electron"

energymatterspeed-> thank you for putting me in my place. That link you posted seems like a bunch of mindless babble (just like most of my posts). I admit I haven't done any calculating of my ideas, and maybe I should come up with some numbers and relations before I ask for other people's opinion's on the idea. I do admit the idea is kinda odd, but it makes sense when you figure the reason why I chose to make that one beginning assumption (all particles are mulpiply connected to the big bang). But ya, my idea is too weird to even give time to think about. that's prolly why everybody would rather talk about radii.

Lose your name, I think maybe you're getting the hydrogen atom and the electron confused. The electron doesn't have states like 1s, or 2p, it just has spin up or spin down. but ya, the "radius" is "fuzzy"

The question "what is a particle" has not been answered. As well as string theory there are vacuum field theories and variations of quantum theory such as:

"Are All Particles Identical?"
Sheldon Goldstein, James Taylory, Roderich Tumulkaz, and Nino Zanghox
PACS numbers 03.65.Ta. (foundations of quantum mechanics) published September 28, 2004; (appendix 1)

Imagine a drop of water in space, as long as it does not break up, it can adopt any shape, including waveform. Given that all single waveforms spin at the same rate; then both force and wavelength are dependent on its amplitude: the water drop can be a sphere or a wave and still be the same water.
Now you can play with this model in various ways (for example, separate wave energy from the water), to create your own vision of how nature works. Compare your model with known experimental results. when you have one that matches experimental work; your model is as good as any other: that's particle physics.
Any model that matches all experiments must also comply with quantum theory (i.e. be capable of matching the mathematical predictions), so your model would also be a viable interpretation and if good enough, would replace the standard model interpretation; that is the main aim of current theory development.

ok, well I calculated the radius of the elcetron using my relation. If I use 1094 grams per cubic centimeter as the density in the big bang (corresponding to a time of 10^-43 seconds) I get a radius of 5.836084753863517*10^-13 meters... hmm, i would guess it would be a little bit fudged because we're trying to avoid running into singularities. Hmm, also, that radius corresponds to equal pressure on both "sides" of the particle (one "side" being the density in the big bang and the other the density of the particle). Suppose that because of general relativity, matter curves space in a way that for all matter, there is an influx of space-time. Then would I need to say that the energy-density of the space influx into a particle must be a tad bit greater than the energy density at the big bang, otherwise if they were equal, there would be no influx (no curvature of space-time) around the particle, and therefore it would have no mass... This could also have fudged my calculation because I set it up so the energy-densities are equal, and maybe I should have set it up so that the energy of the influx of space into a particle is proportional to it's mass.

For want of being rude, you are talking complete and utter bollocks. We have a very similar situation here to that of the 'division by zero' thread over on the maths forum. I suggest you read some basic quantum mechanics texts before starting on wild speculation that 'sounds right' as far as your completely uninformed view permits.

## What is an Electron?

An electron is a subatomic particle that carries a negative charge and is located outside the nucleus of an atom.

## What is the radius of an Electron?

The radius of an electron is approximately 2.8179 x 10^-15 meters.

## Is an Electron considered a substance?

No, an electron is not considered a substance as it is a fundamental particle and does not have a distinct physical structure or composition.

## What are quarks and their relationship to Electrons?

Quarks are even smaller subatomic particles that make up protons and neutrons, which in turn make up the nucleus of an atom. Electrons do not contain quarks and are not affected by the strong nuclear force that binds quarks together.

## How does the number of Electrons in an atom affect its properties?

The number of electrons in an atom determines its chemical properties, such as its reactivity and ability to form bonds with other atoms. The arrangement of electrons in an atom also affects its physical properties, such as its conductivity and melting point.

• Electromagnetism
Replies
14
Views
926
• Electromagnetism
Replies
2
Views
806
• Electromagnetism
Replies
1
Views
1K
• Electromagnetism
Replies
2
Views
1K
• Electromagnetism
Replies
16
Views
1K
• High Energy, Nuclear, Particle Physics
Replies
17
Views
2K
• Electromagnetism
Replies
7
Views
1K
• Electromagnetism
Replies
28
Views
2K
• Electromagnetism
Replies
16
Views
1K
• High Energy, Nuclear, Particle Physics
Replies
9
Views
1K