Explaining the Difference in Charge between Particles

[Messiri]

Why do oppositely charged particles attract? I know this question was asked on PF a while ago, but the answers given do not seem too convincing.

I understand that, by Coulomb's Law, there are attractive and repulsive forces between charged particles, proportional to the product of the particle's charges and inversely proportional to the square of the distance between them.

But, for example, why is there an attractive force between electrons and protons? What makes the proton intrinsically different to an electron, what property gives it a different "kind" of charge?

I would be grateful if someone could explain to me where the difference in charge stems from.

 

[DiracPool]

Charge is a fundamental property of matter, in a "first cause" sort of way. It is, at present, one of the fundamental building blocks of physical models, not reducible to a more fundamental architecture of constituents. So to ask why charge exists is kind of like asking why gravity exists, or why matter exists. The answer is that, at present, we don't know. But we have to start somewhere, so we label or give names to different phenomena and then formulate equations and test these formulations against experiment. "Charge" is a name that was given to a property of materials that behaved in a certain manner. It was later found out that charge was quantized via the Millikan Oil Drop Experiment. These quantized charges were called electrons and given a negative (-1) label to contrast from the proton, which had a (+1) label. It was later found that the proton was composed of three quarks with partial charges that add up to +1. Why these charges should perfectly balance each other in terms of coulomb units is still baffling to scientists, as far as I'm aware. I don't think that there's any insight into the issue that you are missing.

 

[Andrew Mason]

Just to follow up on what DiracPool has said, scientists tend to develop theories that explain phenomena in terms of more fundamental phenomena. Inevitably, one reaches a point that cannot be reduced to something more fundamental. Whether we have reached that point with charge is not yet clear. But we might have.

Science does not provide answers to questions like "how did the laws of physics originate", "is there a God", or "are there other universes that we cannot interact with?"; or "why is there charge". These are interesting questions that we would all like to have answers to. But science can't provide them - at least not yet.

AM

 

[jtbell]

In classical physics, electric charge and the electric and magnetic force laws are unexplained. They are taken as "given", in the same way as mass and F = ma in Newtonian mechanics.

In quantum field theory, one can derive the existence of charge and the laws of electrodynamics (Maxwell's equations) from something called "local U(1) gauge symmetry."

But that simply begs the question, "why does the universe obey local U(1) gauge symmetry?"

 

[sugeet]

Very nice question Messiri!
I would look at it this way, everything is made finally by quarks and leptons. Quarks are charged, that's their nature, they have a few properties, like we all have height, weight etc, like that these things have properties called charge, strangeness, mass etc. Protons are made of quarks which add up to a charge of +1, and electrons are leptons with charge -1. Its like their natural property. Everything has this property, things around us, books, sand, air water etc. Macroscopically things are generally neutrally charged. Charge is not a thing, its a property. when we say charges flow, what flows is particles having non-zero charge, there is no-thing as charge!

 

[FredericGos]

In quantum field theory, one can derive the existence of charge and the laws of electrodynamics (Maxwell's equations) from something called "local U(1) gauge symmetry."

Hi jtbell,

I'm curious, can you point me to papers, books or articles where I can read about this derivation? Sounds really interresting. thx.

/Frederic

 

[Messiri]

^second