## Charge +/-

• 214
One thing I find peculiar about the universe is it’s habit of making charged things; protons and electrons, positrons and antiprotons, ions, anions etc.

The only reason we know of them as “charged” is that they avoid some things and attract towards other things. It’s not as if they have a little plus or little minus attached, these two terms are relatively arbitrary, you could just as easily use A and B instead or 1 and 0 or yin and yang it doesn’t matter they simply define the relative nature of the two species and their interactions with each other and electromagnetic fields.

It’s seems odd then that we don’t apply this same principle to gravity. That gravity - being an attractive force between matter - doesn’t have a charge. Or that entropy - being a tendency to disperse or repel to the furthest spread out equilibrium again does not have a charge.

It seems energy and it’s equivalent matter, in general, come in two forms; that which likes to coalesce and that which likes to repel. And considering Newton’s third law of motion; every action has an equal and opposite reaction, it seems that perhaps charge is fundamentally necessary. After all they are relative to one another you can’t have a positive without a negative.

So is the universe somehow built of equal parts this and that? Is there some kind of irreconcilable division that exists at the core of everything?
Or, maybe creating a charge is the only way to turn zero (neutrality)/nothingness into somethingness (Information).
• 747
Mass is considered a charge, charge being generalised to cover electromagnetics, nuclear force, and gravity. Why it's positive and negative is simple: a hydrogen atom, consisting of one proton and one electron, has a net charge of e + -e = 0.

Charges are properties of elementary particles. Thermodynamics is the behaviour of groups of particles.
• 5k
Charge is to do with the way a particle spins, or rather its helicity - see https://en.wikipedia.org/wiki/Chirality_(physics)

The helicity of a particle is positive (“right-handed”) if the direction of its spin is the same as the direction of its motion. It is negative (“left-handed”) if the directions of spin and motion are opposite. So a standard clock, with its spin vector defined by the rotation of its hands, has left-handed helicity if tossed with its face directed forwards.

So the difference between an electron and a positron is simply that one is left handed, the other right, in its “spin”.

And the reason that difference can exist is electrons/positrons became massive particles that travel at the less than the speed of light soon after the Big Bang. They were “trapped” into a definite orientation one way or the other.
• 1.4k
Charge is to do with the way a particle spins

No.
• 787
:roll:
• 5k
No.

Yeah. I kind of gave up as soon as I started. So much that has to be unpacked here. :grin:

But it is a good thread topic. The underlying metaphysical question is how do we get these broken symmetries that are ... stably broken?

How does charge become a thing, thus allowing the Universe to be filled with interaction that have some material interest?
• 747
So the difference between an electron and a positron is simply that one is left handed, the other right, in its “spin”.

This is not true. An electron may be spin up or down.
• 5k
This is not true. An electron may be spin up or down.

I was steering towards a discussion of chirality. That should have been obvious.
• 747
I was steering towards a discussion of chirality. That should have been obvious.

Yeah, stupid me.
• 5k
What was at the back of my mind here was the loop quantum gravity (LQG) picture of particles as knots or braided structures in a spacetime "spin network". So charge becomes an intrinsic property of particles because a "chiral twistedness" is locked in.

So this is basically Bilson-Thompson's riff on the Harari-Shupe preon model of how to build up the standard model particles from twisted, and then braided, 2D ribbons. And this view collapses charge and parity into a single formalism (or at least, that was what I have been meaning to check more carefully).

Also important here - in relation to my own viewpoint - is the way helicity and chirality become detached once fermions actually become massive and so cease to move relativistically.

https://www.quantumdiaries.org/2011/06/19/helicity-chirality-mass-and-the-higgs/
https://en.wikipedia.org/wiki/Chiral_symmetry_breaking

So there is another whole conversation to be had about CP violation and how the Universe wound up actually divided into positive charges in the form of protons, and negative charges in the form of electrons.

If electrons and positrons had been produced in exactly even numbers, then negative charge would not have been a thing as they would have mutually annihilated to a sizzle of photons. Likewise a perfectly symmetrical production of protons and anti-protons.

So the speculative metaphysics I had in mind is a physics where spin is the basic notion - in terms of anchoring a picture of a spacetime that then supports a relational geometry. And where charge is then an emergent property due to trapped knots or twists left in the fabric of that geometry of relations as the Universe expands and cools.

As I say, I started to unpack that but ... well I actually had other work to get on with. But the issues still really interest me. :up:
• 787
So the speculative metaphysics I had in mind is a physics where spin is the basic notion

Thanks for the clarification.
• 747
And this view collapses charge and parity into a single formalism (or at least, that was what I have been meaning to check more carefully).

I don't know much about LQG but if P is fixed by C before the symmetry-breaking of the Higgs mechanism and at high (relativistic) energies, that would seem to exacerbate the problem of matter-antimatter imbalance that CP-violation solves. Either way, I'm not sure how you expected anyone to read the above into what you were saying earlier. I was just clarifying that matter and antimatter can have either spin, that's all.
• 7.1k
Good question @Benj96. Got me thinking...and the results...more questions than answers.

Starting off with electric charges, all I want to say is that charges (+/-) are on different particles - positrons (+) and electrons (-). Why does this matter? I don't know the latest best model for an atom but I suppose it's a tweaked version of the solar system model with negatively charged electrons orbiting around a positively charged nucleus. The electron orbit has given way to the electron cloud but the model is similar enough, at least I think it is, to allow me to ask the question, "how do we distinguish electric attractive force from gravity?"

Last I remember, the equations of the force of between opposite electric charges and the Newtonian formulatiom of the force of gravity between two objects are identical in form: F = K*(x1*x2)/(r*r) where K is the relevant constant, x1 and x2 are either the charge or the mass and r is the distance between the objects? Just a random coincidence or are we dealing with the same force, only at different scales?

Ref: Newton's Law of Universal Gravitation and Coulomb's Law

An odd coincidence worth noting in my opinion is that Charles-Augustin de Coulomb (1736 - 1806) who discovered Coulomb's Law and
Joseph-Louis Lagrange (1736 - 1813) who was the first to treat time as a fourth dimension were born in the same year.

Either Coulomb's law can explained in terms of a fourth dimension just like gravity or gravity is, well, a force to reckon with. :smile:
• 747
Just a random coincidence or are we dealing with the same force, only at different scales?

Could be the latter but, even if electric and gravitational forces have no identification at any scale, it is not a coincidence. The inverse square law is a consequence of geometry and conservation laws. If you picture an arbitrarily thin, spherical shell around a point charge/mass at its centre, the amount of radiative energy in that shell must equal the amount in any other shell, since it all radiates from the same point. Since the shell area increases as r^2, the energy density must decrease as r^2.
• 7.1k
Since the shell area increases as r^2, the energy density must decrease as r^2

Indeed, the surface area of a sphere is directly proportional to r^2. Ergo energy density assumed as energy/r^2 should decrease to the same extent. I thought density is a volume thing.

The Lagrangian side to this tale is more interesting then - replacing the concept of electric force with a fourth dimensional counterpart, whatever form or shape suits the situation.

Thanks.
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