Question: Why are there only two kinds of electric charges? Why do quarks come in three colors? Why do quarks have fractional charges of 1/3 and 2/3, while other elementary particles like electrons carry an integer charge?
Reply: Those are the basic rules or laws of Nature that we discovered. We don’t know why these are the rules. And if we find a more fundamental rule from which these rules are deduced, we will just replace one why with another. So we have to either a) acknowledge these as brute facts without explanation, or b) we can attribute them to the choice of a wise creator.
Question: If we posit a creator: Why is it more rational to infer that an intelligent designer instantiated this fact of affairs, rather than not?
Answer: Because the outcome of this state of affairs is that we are here. And if the state of affairs would be different, we wouldn't.
1. If you throw the electric charges and quarks together at random, you get no atoms and a dead universe.
2. So in fact, the electric charges and quarks were was not thrown together at random, but selected carefully to permit stable atoms, and a life-permitting universe.
3. Of course, we can appeal to physics that we don't even know, and posit a multiverse, and that random shuffling of these fundamental constants did permit that one emerged permitting a functional outcome, but that would just be a multiverse of the gaps argument.
4. The best explanation is that an intelligent designer created the right constants, fundamental forces, charges, colors etc. that produced stable atoms, and a life-permitting universe for his own purposes.
Leonard Susskind The Cosmic Landscape: String Theory and the Illusion of Intelligent Design 2006
The quark masses vary over a huge range from roughly 10 electron masses for the up-and down-quarks to 344,000 electron masses for the top-quark. Physicists puzzled for some time about why the top-quark is so heavy, but recently we have come to understand that it’s not the top-quark that is abnormal: it’s the up-and-down-quarks that are absurdly light. The fact that they are roughly twenty thousand times lighter than particles like the Z-boson and the W-boson is what needs an explanation. The Standard Model has not provided one. Thus, we can ask what the world would be like if the up-and-down quarks were much heavier than they are. Once again—disaster! Protons and neutrons are made of up-and down-quarks. According to the quark theory of protons and neutrons, the nuclear force (force between nucleons) can be traced to quarks hopping back and forth between these nucleons. If the quarks were much heavier, it would be much more difficult to exchange them, and the nuclear force would practically disappear. With no sticky flypaper force holding the nucleus together, there could be no chemistry. Luck is with us again.
Anjan Sadhukhan QUANTIZED CHARGE & FRACTIONAL CHARGE: FEW FACTS, FINDINGS AND NEW IDEAS June 3, 2020
The physical world around us is made up of different atoms and molecules which are the building blocks of the Universe. Molecules are the collection of atoms and atoms are consisting of neutral neutrons, negatively charged electrons, and an equal number of positively charged protons. Atoms are effectively charged neutral. However, any system possessing an unequal number of electrons and protons is referred to as the ionic system.
What is charge?
The charge on the electron is a fundamental constant of nature.
It is one of the most fundamental questions of nature. Like mass, charge is also a physical property. If we place an object in the gravitational field, due to “mass” it will experience force. In the same way, a charged particle experiences force in the electromagnetic field due to the presence of “charge” in it. It’s well accepted that e is the smallest available independent charge in the physical world. However, the composite particles like neutrons and protons are made up of some elementary particles called ‘quarks’ having smaller charges, multiple of e/3.
It's as if an electron says: hey quarks, let's team up, let's make an atom. Quarks: Hey, great idea, how much electric charge do you have? (Let's call it e). OK so we will team up of three of us, so we will just take each of us -1/3 or 2/3 of your charge. Electron says: Great!, I feel it, this way we can have a stable atom. Quarks: Great! ( Or maybe it was rather their creator thinking about that, in order to make, in the end, you and me ?! ) It seems that the quarks teamed up exactly so three of them can cancel out (attract) exactly the electron's electric charge. Now, here is the thing: More elaborate composite nucleon models can have constituent partons with other rational multiples, and eventually not cancel out with the charge of the electron, and there would be no stable atoms, but ions, and no molecules, and life in the universe !! Composite particles could result in fractional charges. For example, 2 quarks and one anti-quark could sum up and result in a fractional charge ( 1/3).
So is this state of affairs coincidence, or the result of the thoughts of our wise creator?
Q & A: Quarks and Fractional Charges 12/28/2009
Protons have charge +1, and electrons, -1, using units of e. The charge of an atom or composite particle is found by adding the charges of its protons and electrons (since neutrons are electrically neutral). Therefore, the charges of such particles are integer values. However, there are subatomic particles with fractional charges. It turns out that protons and neutrons are composed of particles called "quarks." These quarks, which come in different "flavors" (up, down, charm, strange, top, bottom) make up certain particles. They have fractional charge. Up, charm, and top all have fractional charge of +2/3, while down, strange, and bottom all have a charge of -1/3. Protons are composed of two up quarks and one down quark, so the total charge is +1. Likewise, neutrons are composed of two down quarks and one up quark, so the total charge is 0. Quarks are confined to the particles they compose. This is, appropriately, referred to as "confinement." This is why we don't observe quarks--and therefore their fractional charges--outside their composite particles (such as protons and neutrons).
Quarks have a real fraction of the elementary charge (-1/3 or 2/3). Baryons are made up of three quarks, and that those quarks can have -1/3 or 2/3 the elementary charge. This way, the quarks can combine so that the Baryon will have an integer of the elementary charge. This way, the nucleus, and the electron can be in a stable atomic state, where their electric charges cancel (attract) exactly. Any other way, the atom would not be stable.
In reality, the charge of the electron is not an integer, it is 1.6021765 × 10−19 coulomb, or 4.80320451 × 10−10 electrostatic unit (esu, or statcoulomb). Any amount of charge is nothing but the integer multiple of small units of charge, called the elementary charge, e, which is equal to Coulomb (SI unit of charge). The interaction between charged objects is a non-contact force that acts over some distance of separation.
In particle physics and physical cosmology, Planck units are a set of units of measurement defined exclusively in terms of four universal physical constants, in such a manner that these physical constants take on the numerical value of 1 when expressed in terms of these units.
The electromagnetic force is the Coulomb interaction. This is the familiar law that says that like charges repel each and opposites attract. This law alone dominates the interactions between essentially all objects larger than an atomic nucleus (10−15 meters) and smaller than a planet (10^7 meters).
Where do quarks get their charge?
Science has no answer to why nature uses certain fundamental rules and physical laws and not some other rules that we can conceive. That is probably a question best left to priests or philosophers. For example, the electric charge is an intrinsic property of charged particles and it comes in 2 flavors: positive and negative. Even scientists don’t know where it comes from; it’s something that’s observed and measured. It gets worse: nobody knows how let alone why opposite charges attract and similar charges repel according to Coulomb’s law.
Those are the basic rules of Nature that we discovered. We don’t know why these are the rules. And unless we find a more fundamental rule from which these rules are deduced, we will never know the answer to that why question (and even then, we’d just replace one why with another.)
Bill C. Riemers Ph.D. Experimental High Energy Physics, Purdue University July 17, 2016
The smallest observable NET charge for a charged set of quarks is 1. But the quarks that make up the group have a fractional charge. This is far more of a complex result than anyone would have ever reasonably expected. But it is 100% consistent experimental observations. My best answer as to why quarks have a fraction charge is if there is a GOD, then GOD is both extremely clever and GOD has a really twisted sense of humor (as this seems like an Easter Egg in the laws of physics.) God also seems to appreciate the beauty of higher mathematics.
Closer to truth: WHY COSMIC FINE-TUNING DEMANDS EXPLANATION
The electric charge on the proton is exactly equal and opposite to that of the electron to as many decimal places as you care to measure. This is more than slightly anomalous in that the proton and the electron share nothing else in common. The proton is not a fundamental particle (it is composed in turn of a trilogy of quarks), but the electron is a fundamental particle. The proton's mass is 1836 times greater than that of the electron. So how come their electric charges are equal and opposite? Why is it so? There is no reason why this state of affairs could not be different! Actually, there is an infinite number of possible different arrangements which would prohibit setting up stable atoms. Why is the electric charge on the electron is exactly equal and opposite to that of the positron, the positron being the electron's antimatter opposite? That equal but opposite charge is again verified to as many decimal places as one can calculate. So that means the electric charge on the proton and the electric charge on the positron are exactly the same, yet apart from that, the two entities are as alike as chalk and cheese. Why is it for this electric charge equality between different kinds of particles?
Jason Waller Cosmological Fine-Tuning Arguments 2020, page 100
Fine-Tuning in Particle Physics What would happen to our universe if we changed the masses of the up quark, down quark, and electron? What would happen to our universe if we change the strengths of the fundamental forces? And what would happen to our universe if we eliminated one of the four fundamental forces (gravity, electromagnetism, strong force, weak force)? In each of these cases, even relatively minor changes would make the existence of intelligent organic life (along with almost everything else in our universe!) impossible. “The neutron-to-proton mass ratio is 1.00137841870, which looks . . . uninspiring. Physically this means that the proton has very nearly the same mass as the neutron, which . . . is about 0.1 percent heavier”. At first, it may seem as though nothing of significance hangs on this small difference. But that is wrong. All of life depends on it. The fact that the neutron’s mass is coincidentally just a little bit more than the combined mass of the proton, electron, and neutrino is what enables neutrons to decay. . . . If the neutron were lighter . . . yet only by a fraction of 1 percent, it would have less mass than the proton, and the tables would be turned: isolated protons, rather than neutrons, would be unstable. Isolated neutrons will decay within about fifteen minutes because particles tend toward the lowest possible energy consistent with the conservations laws. Given this tendency of fundamental particles, the slightly higher mass of the neutron means that the proton “is the lightest particle made from three quarks. The proton is stable because there is no lighter baryon to decay into. The ability of the proton to survive for an extended period without decaying is essential for the existence of life. In the early universe, there was a “hot, dense soup of particles and radiation,” and as the universe began to cool, the heavier elements decayed into protons and neutrons. The Universe managed to lock some neutrons away inside nuclei in the first few minutes before they decayed. Isolated protons were still important chemically because they could interact with electrons. In fact, a single proton is taken as an element even in the absence of any electrons—it is called hydrogen. But now imagine an alternative physics where the neutron was less massive, then free protons would decay into neutrons and positrons, with disastrous consequences for life, because without protons there could be no atoms and no chemistry. Neutrons are electrically neutral and so will not interact with electrons. That means a universe dominated by neutrons would have almost no interesting chemistry. A decrease in the neutron’s mass by 0.8 MeV would entail an “initially all neutron universe. It is rather easy to arrange a universe to have no chemistry at all. If we examine a range of different possible masses for the up and down quarks (and so the proton and neutron), we can conclude that almost all changes lead to universes with no chemistry. Thus, there are firm and fairly narrow limits on the relative masses of the up and down quarks if our universe is going to have any interesting chemistry.
Another problem with a lighter neutron is that a small decrease in neutron mass of around 0.5 to 0.7 MeV would result in . . . an almost all helium universe. This would have serious life-inhibiting consequences since helium stars have a lifetime of at most 300 million years.
Let’s turn to the electron. “The ratio of the mass of the proton to that of the electron is 1,836.1526675—an utterly mundane number. It is the electrons that account for all of chemistry. It is the electrons that allow chemical bonds to form and so allow for solids to exist. When two atoms or molecules come together and shuffle electrons, a chemical reaction has occurred. Sometimes the electron is not pilfered but shared: as the two atoms or molecules wrestle for possession of the electron, a chemical bond is formed.
In solids, atoms are held together by chemical bonds in a fixed lattice. . . . We can break this lattice by shaking it vigorously. Given quantum mechanics, we know that the particles in the universe are constantly jiggling and moving. In fact, it is this constant jiggling that makes it impossible to bring something to absolute zero, which would require all atomic motion to stop. If we are imagining increasing the mass of the electron, then this quantum jiggling becomes a significant problem for the stability of solid structures. If the electron mass were within a factor of a hundred of the proton mass, the quantum jiggling of electrons would destroy the lattice. In short: no solids. So there is a firm-fixed range for the mass of the electron—it can range from 0 to about a factor of a hundred times smaller than the mass of the proton before life as we know it becomes impossible. We see from these very brief considerations that the masses of the fundamental particles cannot be changed very much relative to one another without losing chemistry (and so organic life).
But in addition to the fundamental particles, there are also four fundamental forces: gravity, electromagnetism, the strong force, and the weak force. What happens if we imagine varying the strengths of these forces? Let’s begin with gravity. Gravity is weaker than electric forces by a huge amount (about 10^36 times weaker). “Imagine for instance [if] gravity was only 10^30 rather than 10^36 feebler than electric forces. Atoms and molecules would behave as in our actual universe, but objects would not need to be so large before gravity became competitive with the other forces”. This would require planets and stars to be scaled down by a factor of about a billion. We would also need to be scaled down as well because gravity would crush anything as large as ourselves. Rees argues that even small bugs would have to have very thick legs. But so far this seems to be an interesting universe with chemistry and organic life (albeit smaller organic life). But there are some significant problems. One of the biggest problems is the lifetime of the typical star. Instead of being around for 10 billion years, the average lifetime would be much shorter. Interestingly, Rees concludes that the weaker gravity is (provided it isn’t actually zero), the grander and more complex can be its consequences. But if we strengthen gravity much more than Rees imagines, then the consequences are even more dire. This grants gravity a rather firm upper bound relative to the electromagnetic force. Furthermore, if gravity were less than 0, then it would be a repelling force with obvious dire consequences. Collins calculates the quantity of fine-tuning here (assuming an upper bound of the strength of the strong force) as 1 part in 10^36. Even if we are skeptical of these exact calculations, we can safely conclude that the life-permitting range is extremely small.
Now let’s turn to the relative strengths of the strong force and the electromagnetic force. The strong force is the force that holds the nucleus of an atom together, and the electromagnetic force is the force that keeps electrons in orbit around a nucleus. “The effect on the stability of elements of decreasing the strong force is straightforward, since the stability of elements depends on the strong force being strong enough to overcome the electromagnetic repulsion between protons in a nucleus”. Since protons all have a positive electric charge and like charges repel each other, weakening the strong force would make it substantially harder for the nucleus of an atom to hold together. But how much can we imagine weakening the strong force before a nucleus with more than one proton becomes unstable? Doing the required calculations tells us that a “50 percent decrease in the strength of the strong force . . . would undercut the stability of all elements essential for carbon-based life, with a slightly larger decrease eliminating all elements except hydrogen” (Collins 2003: 183; Barrow and Tipler 1986: 326–327). Because it is the relative strengths of the forces that matters, one can reach the same instability with about a fourteen-fold increase in the electromagnetic force. This entails (keeping everything else the same) that in terms of atomic stability, there is a firm upper bound to the strength of the electromagnetic force (and, of course, it cannot fall below 0). The ratio between these forces is also significant when it comes to the production of heavy elements in stars.
Based on recent computer models, Stephen Hawking and Leonard Mlodinow report that
a change of a little as 0.5 percent in the strength of the strong nuclear force, or 4 percent in the electric force, would destroy either nearly all carbon or all oxygen in every star, and hence the possibility of life as we know it. Let’s turn to what would happen if we imagine eliminating a force from our universe (or imagine its value as 0). Interestingly, we can quickly infer that without gravity, electromagnetism, or the strong force, there is little chance for a life-permitting universe.
If gravity did not exist, masses would not clump together to form stars or planets . . .
If the strong force didn’t exist, protons and neutrons could not bind together and hence no atoms with an atomic number greater than hydrogen would exist.
If the electromagnetic force didn’t exist, there would be no chemistry.
A universe without the weak interactions would be a universe where neutrons would be stable, and all protons and neutrons would be forged into helium, leaving behind the merest trace of hydrogen.
This is bad news for stars, water and almost all known organic molecules. In addition to the four fundamental forces, there are other laws of physics which if eliminated would prohibit life from evolving in our universe. Collins mentions two (the “Pauli exclusion principle” and the “quantization principle.”) If Pauli exclusion principle, which dictates that no two fermions can occupy the same quantum state, did not exist, all electrons would occupy the lowest atomic orbit, eliminating complex chemistry. If there were no quantization principle, which dictates that particles can only occupy certain discrete allowed quantum states, there would be no atomic orbits and hence no chemistry, since all electrons would be sucked into the nucleus.
In short, doing the required calculations reveals that each of the masses of the fundamental particles and relative strengths of the different forces cannot be changed much without eliminating intelligent organic life.
Fine-Tuning in Quantum Mechanics
The rules of quantum mechanics are, of course, very different from the rules of classical mechanics. In classical physics, the rules are deterministic and each object has both a place and a definite velocity. But in quantum mechanics, “it’s a bit more complicated. Particles such as electrons have wave-like properties, so we describe them with a wave function whose peaks and troughs tell us where the electron probably is, and where it is probably going”. It is very good news for our universe that classical physics does not hold at the level of atoms, because if it did then atoms would be unstable. But classical mechanics does hold for larger objects like people, plants, and planets. So where is the boundary line between the quantum and the classical? The answer lies in Planck’s constant, which has been experimentally found to have the value of 6.62606957 × 10−23 kg m3 s−2 in our universe. Below this size and the rules of quantum mechanics hold, and above this size the rules of classical mechanics hold (with some complications not directly relevant to this argument).17 What would happen if we changed Planck’s constant? If we brought the constant to 0, then classical mechanics would hold not only for medium-sized objects like us, but also for atoms too. This would be a disaster for our universe because atoms would become unstable “as electrons lose energy and spiral into the nucleus”. Such a universe could not have much interesting chemistry. But what if we made Planck’s constant considerably larger? In this imaginary universe, medium-sized material objects would behave in quantum-like ways. While there are tricky philosophical questions about how to interpret quantum mechanics, we can be sure that if ordinary medium-sized objects behaved according to these laws, the world would be a very different place. In such a world bodies would have to be “fuzzy.” “It would be like Schrodinger’s ‘quite ridiculous’ cat, never knowing where things are or where they are going. Even more confusingly, its own body could be similarly fuzzy” . While it is unclear exactly what such a world would look like, we would know that it would not be obeying the laws of classical mechanics and that objects would have to behave in both wave-like and particle-like ways. Whether it would be possible to hunt down a boar who moved according to a wave function is far from clear (at best!), not to mention that I could not have both a place and a determinate velocity at the same time. Imagine kicking a ball in a world with a very large Planck’s constant and both the world around us [and] the ball would be radically unpredictable. This lack of predictability would be a significant problem for the existence of life. Thus, it seems as though Planck’s constant has to be relatively close to its current value for both atoms to be stable and life to be possible.
Ian Morison: A Journey through the Universe page 362
Half of the gravitational potential energy that arose from this inflationary period was converted into kinetic energy from which arose an almost identical number of particles and antiparticles, but with a very small excess of matter particles (about one part in several billion). All the antiparticles annihilated with their respective particles leaving a relatively small number of particles in a bath of radiation. The bulk of this ‘baryonic matter’ was in the form of quarks that, at about one second after the origin, grouped into threes to form protons and neutrons. (Two up quarks and one down quark form a proton, and one up quark and two down quarks a neutron. The up quark has +2/3 charge and the down quark −1/3 charge, so the proton has a charge of +1 and the neutron 0 charge.)
Stephen C. Meyer: The return of the God hypothesis, page 185
For instance, to make life possible, the masses of the fundamental particles must meet an exacting combination of constraints. In the previous chapter, I discussed the fine-tuning of the masses of the two naturally occurring quarks, the up quark and down quark, in relation to the range of expected possible values. Recall that the fine-tuning of the masses of those quarks is considerable—1 part in 10^21 . In addition, the difference in masses between the quarks cannot exceed one megaelectron volt, the equivalent of one-thousandth of 1 percent of the mass of the largest known quark, without producing either a neutron-only or a proton-only universe, both exceedingly boring and incompatible with life and even with simple chemistry. Equally problematic, increasing the mass of electrons by a factor of 2.5 would result in all the protons in all the atoms capturing all the orbiting electrons and turning them into neutrons. In that case, neither atoms, nor chemistry, nor life could exist. What’s more, the mass of the electron has to be less than the difference between the masses of the neutron and the proton and that difference represents fine-tuning of roughly 1 part in a 1000. In addition, if the mass of a special particle known as a neutrino were increased by a factor of 10, stars and galaxies would never have formed. The mass of a neutrino is about one-millionth that of an electron, so the allowable change is minuscule compared to its possible range. The combination of all these precisely fine-tuned conditions—including the fine-tuning of the laws and constants of physics, the initial arrangement of matter and energy, and various other contingent features of the universe —presents a remarkably restrictive set of criteria. These requirements for the existence of life, again defying our ability to describe their extreme improbability, have seemed to many physicists to require some explanation.
Strikingly, the masses of “up quarks” and “down quarks,” the constituent parts of protons and neutrons, must have precise values to allow for the production of the elements, including carbon, essential for a life-friendly universe. Indeed, the masses of these quarks must have simultaneously nine different conditions for the right nuclear reactions to have occurred in the early universe. The “right” reactions are ones that would produce the right elements (such as carbon and oxygen) in the right abundances necessary for life. The fine-tuning of the masses of these two naturally occurring quarks in relation to the range of expected possible values for the mass of any fundamental particle is exquisite. Physicists conceive of that range as extending between a mass of zero and the so-called Planck mass, an important unit of measure in quantum physics. But the value of the “up quark” must have a precise mass of between zero and just one billion trillionth of the Planck mass, corresponding to a fine-tuning of roughly 1 part in 10^21. The mass of the “down quark” must have a similarly precise fine-tuning.
Geraint F. Lewis A universe made for me? 18 December 2016
Imagining a universe, slightly different to our own. Let’s just play with one number and see what happens: the mass of the down quark. Currently, it is set to be slightly heavier than the up quark.
A proton is made of two light-ish up-quarks plus one of the heavy-ish down quarks. A neutron is made of two heavy-ish down-quarks plus one light-ish up-quark. Hence a neutron is a little heavier than a proton.
That heaviness has consequences. The extra mass corresponds to extra energy, making the neutron unstable. Around 15 minutes after being created, usually in a nuclear reactor, neutrons break down. They decay into a proton and spit out an electron and a neutrino. Protons, on the other hand, appear to have an infinite lifespan.
This explains why the early universe was rich in protons. A single proton plus an electron is what we know as hydrogen, the simplest atom. It dominated the early cosmos and even today, hydrogen represents 90% of all the atoms in the universe. The smaller number of surviving neutrons combined with protons, losing their energy to become stable chemical elements.
Now let’s start to play. If we start to ratchet up the mass of the down quark, eventually something drastic takes place. Instead of the proton is the lightest member of the family, a particle made of three up-quarks usurps its position. It’s known as the Δ++. It has only been seen in the rubble of particle colliders and exists only fleetingly before decaying. But in a heavy down-quark universe, it is Δ++ that is stable while the proton decays! In this alternative cosmos, the Big Bang generates a sea of Δ++ particles rather than a sea of protons. This might not seem like too much of an issue, except that this usurper carries an electric charge twice that of the proton since each up-quark carries a positive charge of two-thirds.
As a result, the Δ++ holds on to two electrons and so the simplest element behaves not like reactive hydrogen, but inert helium.
This situation is devastating for the possibility of complex life, as in a heavy down-quark universe, the simplest atoms will not join and form molecules. Such a universe is destined to be inert and sterile over its entire history. And how much would we need to increase the down quark mass to realize such a catastrophe? More than 70 times heavier and there would be no life. While this may not seem too finely tuned, physics suggests that the down-quark could have been many trillions of times heavier. So we are actually left with the question: why does the down-quark appear so light?
Things get worse when we fiddle with forces. Make the strength of gravity stronger or weaker by a factor of 100 or so, and you get universes where stars refuse to shine, or they burn so fast they exhaust their nuclear fuel in a moment. Messing with the strong or weak forces delivers elements that fall apart in the blink of an eye, or are too robust to transmute through radioactive decay into other elements,
Examining the huge number of potential universes, each with their own unique laws of physics, leads to a startling conclusion: most of the universes that result from fiddling with the fundamental constants would lack physical properties needed to support complex life.
Electric Charge: An Example of Fine-Tuning? 10 Jan 2014
The electron, the proton, and the quark are all entities within the realm of particle hence quantum physics. All three carry an electrical charge. All three have mass. After those observations, things get interesting, or messy, depending on your point of view. The electric charge of the proton is exactly equal and the opposite of the electric charge on the electron, despite the proton being nearly 2000 times more massive. There’s no set-in-concrete theoretical reason why this should be so. It cannot be determined from first principles, only experimentally measured.
The Structure of the Atom
An electron has a negative charge exactly equal and opposite to that of a proton. Note: the charge is exactly equal, even though the proton has a far greater mass than the electron (some 2000 times heavier in fact, not that there has to be of necessity any relationship between mass and charge).
Now that’s strange since the electron is a fundamental particle but the positively charged proton is a composite particle, made up of a trio of quarks (as is the neutron with no net charge). The proton has two quarks each with a positive 2/3rds charge (up quark) and one quark with a negative 1/3rd charge (down quark) for an overall balance of one positive charge. (The neutron, on the other hand, has one up quark with a positive 2/3rds charge and two down quarks each with a negative 1/3rd charge, for an overall balance of zero charge – neither positive nor negative.)
Now you might suggest that an electron might be a fusion of a trio of down quarks, each with a negative 1/3rd charge, except the electron, again, isn’t a composite particle, and the mass is all wrong for that scenario. If an electron were a composite of a trio of down quarks, each with a minus 1/3rd charge, the electron would be thirty times more massive than it is – not something particle physicists would fail to take notice of.
Further, the force particle that governs the electron is the photon; that which governs the quarks inside the proton and the neutron is the gluon, which further differentiates the two things – quarks and electrons. In any event, if you could have a composite particle of a trio of negative 1/3rd down quarks, if that were the case, and it is the case, and it’s called the Negative Delta, you’d also need a composite particle that’s the fusion of a trio of positive 2/3rds up quarks for an overall charge of plus two. To the best of my knowledge, there is only one such critter in the particle zoo and it’s called the Doubly Positive Delta. I’m sure you’ve never heard of these Delta particles, which goes to show how much bearing or impact they have on life, the Universe, and everything.
In case you were wondering, there would be an anti-quark of minus 2/3rds charge, and an anti-quark of a positive 1/3rd charge, to yield an antiproton and an anti-neutron. The anti-proton would of course have an equal and opposite charge to the anti-electron (which has a formal name – the position). So things are equally as mysterious in the realm of the anti-world.
Question: How do you get 1/3rd or 2/3rds of an electric charge in any event? Of course one could just multiply by three and that does away with the fractions, but that doesn’t resolve the larger issues, like for that matter, what exactly is electric charge and how does it come to be?
Presumably, quarks inside of protons and neutrons, and electrons could have taken on any old values of charge, separate and apart, but didn’t. Why? Is this evidence for a Multiverse (where anything that can happen does happen in all possible combinations); intelligent design (which does not of necessity imply a deity – just a creator, or a programmer); or just a coincidence?
Equal and opposite charges between the proton and the electron would just seem to be one of Mother Nature’s little mysteries. Why is it so? What does it mean? Is it one of those numerous examples of fine-tuning that makes life, and thus you, possible? You could imagine the consequences if the electric charge on the proton and on the electron were different!
But something else is odd here. The proton, as noted above, is 2000 times more massive than the electron, but if you weigh up the trio of quarks* that make up the proton, the proton should only come in at roughly 20 times that of an electron. That’s 100 times too small. So where do the other 1980 bits of mass come from? Well the gluon that holds the proton’s (and the neutron’s) quarks together, like the electron’s photon and gravity’s (theoretical or hypothetical) graviton, have no rest mass that adds to the total. But the internal jiggling of the quarks and their gluon companions does add a bit more mass to the proton. Remember that motion equals energy which equals mass. Finally, that leaves the vacuum energy to fill the remaining gap.
Last edited by Otangelo on Fri Jul 30, 2021 10:40 am; edited 24 times in total