Why do positive and negative charges attract?


by Karmic Leprec
Tags: attract, charges, negative, positive
Kevin_Axion
Kevin_Axion is offline
#37
Aug12-10, 06:00 PM
P: 920
Quote Quote by FizixFreak View Post
you have probably gotten the answer but i think that string theory can give a more logical yet complex explanation you must be familiar with the curves in the space time fabric that causes every single object in the universe to attract the any other object causing what we know as gravitational pull.
the electrostatic force is found to be caused by same type of curves in space but since our three dimensions are already covered up by gravitational force there must be other dimensions in the universe in which the curves are caused by charged bodies so the uncharged bodies only create curves in the three dimensional space but charged bodies also create curves in other dimensions and because of these curves the charges attract to each other here is a link. in this video they talk not about the electrostatic force but unified EM force hope you find it helpful http://www.youtube.com/watch?v=YtdE662eY_M
( i might have made some mistakes here some creative criticism will be appreciated)
Firstly FixiFreak, you're talking about Kaluza-Klein Theory which has been proven incorrect. The curvature of five space-time dimensions produces Maxwell's equations for electromagnetism, Einstein's Field Equations for Gravity and the Radion/Graviscalar. The radion is a hypothetical scalar field which has falsified this theory and also the inconsistency of the theory for producing physical constants has made it inaccurate in describing nature. Also to extend that point, Kaluza-Klein Theory doesn't produce the Quantum Field Theories: Quantum Chromodynamics, and the Electroweak Interactions. So no, Electromagnetism isn't the curvature of five of an extra compactified dimension in Five dimensional space-time and this isn't the correct approach in describing nature. Although the extra dimensions and the geometry of the compactifications into Calabi-Yau Manifolds is etched into the elegance of String Theory.
FizixFreak
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#38
Aug13-10, 05:45 AM
P: 188
Quote Quote by Kevin_Axion View Post
Firstly FixiFreak, you're talking about Kaluza-Klein Theory which has been proven incorrect. The curvature of five space-time dimensions produces Maxwell's equations for electromagnetism, Einstein's Field Equations for Gravity and the Radion/Graviscalar. The radion is a hypothetical scalar field which has falsified this theory and also the inconsistency of the theory for producing physical constants has made it inaccurate in describing nature. Also to extend that point, Kaluza-Klein Theory doesn't produce the Quantum Field Theories: Quantum Chromodynamics, and the Electroweak Interactions. So no, Electromagnetism isn't the curvature of five of an extra compactified dimension in Five dimensional space-time and this isn't the correct approach in describing nature. Although the extra dimensions and the geometry of the compactifications into Calabi-Yau Manifolds is etched into the elegance of String Theory.
so may be you are trying to say that EM force is not caused by warps and curves in the extra dimensions?????????
but it makes so much sense and it also is the basis of string theory and if kaluza was wrong it proves that string theory is false as well may be it failed on some specific points but the main points of the theory which explain the EM force so beautifully just do not seem to be wrong.
Kevin_Axion
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#39
Aug13-10, 09:20 AM
P: 920
Warping of five-dimensional space-time to generate Electromagnetism isn't a physical idea established my String Theory. It also isn't a significant basis for the idea of String Theory, I think your perception of the theory is slightly obscured, you should read through this extensively: http://en.wikipedia.org/wiki/Superstring_theory
FizixFreak
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#40
Aug13-10, 12:52 PM
P: 188
Quote Quote by Kevin_Axion View Post
Warping of five-dimensional space-time to generate Electromagnetism isn't a physical idea established my String Theory. It also isn't a significant basis for the idea of String Theory, I think your perception of the theory is slightly obscured, you should read through this extensively: http://en.wikipedia.org/wiki/Superstring_theory
yes i was wrong about that.
but even if we keep string theory out of this the idea of kaluza still seems quite reasonable if this idea does not explain the EM force then what does(is it that CHARGE DUE TO SPIN STUFF)??????
Kevin_Axion
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#41
Aug13-10, 08:57 PM
P: 920
Yes, many theories appear reasonable but Kaluza-Klein theory isn't predictive or is cohesive with experimentally observed quantities: such as the Electron Mass, and the Coupling Strength of the Electromagnetic force. If you find dimensions to be intriguing then Superstring Theory is an idea that will fascinate you. Superstring Theory's extra dimensions (Calabi-Yau Manifolds) are naturally beautiful and are the basis of the theories predictive power and elegance. Spin is a property of particles, you can think of it as quantized angular momentum, so no charge and electromagnetism is derived from spin. Charge is also a quantum property of particles and charged particles interact with the electromagnetic field and with other particles by exchanging virtual photons.
FizixFreak
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#42
Aug23-10, 01:51 PM
P: 188
Quote Quote by Kevin_Axion View Post
Yes, many theories appear reasonable but Kaluza-Klein theory isn't predictive or is cohesive with experimentally observed quantities: such as the Electron Mass, and the Coupling Strength of the Electromagnetic force. If you find dimensions to be intriguing then Superstring Theory is an idea that will fascinate you. Superstring Theory's extra dimensions (Calabi-Yau Manifolds) are naturally beautiful and are the basis of the theories predictive power and elegance. Spin is a property of particles, you can think of it as quantized angular momentum, so no charge and electromagnetism is derived from spin. Charge is also a quantum property of particles and charged particles interact with the electromagnetic field and with other particles by exchanging virtual photons.
alright akward question but how does these exchanges cause attraction or repulsion i mean why do these exchanges cause the charges to accelarate in a field and what are these virtual photons ??
Kevin_Axion
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#43
Aug23-10, 02:17 PM
P: 920
The sole purpose of this thread was to satsify the question "why do positive and negative charges attract?", many people, including myself included a detailed explanation of how Electromagnetic attraction and repulsion is mediated by virtual photons to charged particles. You ask the question "how do virtual photons cause attraction and repulsion?" Once again there is not one person that knows, it is a property of nature that isn't described through theory, theories such as Quantum Electrodynamics (http://en.wikipedia.org/wiki/Quantum...ynman_diagrams) describe how charged particle are effected by virtual photons (http://en.wikipedia.org/wiki/Virtual_particle) and it describes the physical implications but it doesn't ask the question of Why? It doesn't have to, nor should it because nature doesn't ask the question Why? Human's do, it's a quality of our curiosity.
jVincent
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#44
Aug24-10, 07:38 PM
P: 18
There is a lot of talk in this thread about the nature of your question and whether you should be asking it at all, I think this is unnecessary noise in the discussion.

Why do likes charges attract? Well, lets ask first a more useful question, what is charge? Well charge is a concept we have invented to describe attractive and repulsive forces which we observe between objects. We then went on to describe mathematical formulas which described the nature of these attractions and repulsions.
So the question of why do like charges repel, should really be asked remembering that we ourselves defined the concept of charge based on the repulsion. That is, you are not going to find a question which goes like: "Well, when you have 7 cars in a row, that leads to a charge, and because all cars go the same direction this leads to....."

The reality of the question is that when we do experiments where we transfer a charge to an object, two objects that undergo the exact same charge transfer, be it negative or positive will show a repulsion. Therefor we built the framework with the definitions giving a repulsion for like charges. Later experiments then pinned down the origin of these charges to the subatomic particles.

Of cause a more mathematically complex derivation of a similar result could be given using all the weirdities of quantum mechanics and some would find such an answer more rewarding simply because it contained more equations. However we should remember that QM itself is just a mathematical framework which we built requiring the apparent results of reality to be true, so it doesn't prove anything that it can be used to derive the results it was based on (except that it isn't falsified by those specific experiments).

As Feynman is trying to explain, it is not a case of the answer being unknown, it is a case of the answer being just another level of abstraction invented for the sole purpose of explaining the reality that we find when we cary out experiments. Following down this road your equation becomes.
AJ Bentley
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#45
Aug25-10, 08:18 AM
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I can't answer the question as to why (or how) charges come in two varieties, with contrary properties but there is a QM explanation of the interaction of electromagnetic fields with charge. In a way, that answers the question of how the forces arise.
Is that what you are asking about?
Zhabka
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#46
Aug25-10, 01:11 PM
P: 18
Quote Quote by jVincent View Post
There is a lot of talk in this thread about the nature of your question and whether you should be asking it at all, I think this is unnecessary noise in the discussion.
Agreed! I couldn't believe the stubbornness with which people refused to even consider the question just because it had the word "why" in it. No one even mentioned QED until the second page of posts, shouldn't that have been the very first reply? Obviously no one is expecting a grand-unified-tied-up-in-a-neat-little-package-with-a-nice-looking-bow description of attractive and repulsive forces. But is it really so bad to want something more satisfying than "because that's the way it is", or "its defined that way".

So I send out my respects to Karmic for standing his ground on this! So what if any real discussion on a topic like this will be nothing but conjecture? It never hurts to have a brain storm! After all, before any theory comes into being someone has to first make a guess at a better explanation, only then can you start to see if it holds water.

In my opinion, Faradave gave the best summary of the state of this topic today, hands down. He was a breath of fresh air that made me grin from ear to ear.

***

I wish I had something to add myself, but I don't have much. Although I do remember a few years back when I was in high school. This exact question suddenly started driving me nuts for a few months. At the time I had never heard of Quantum Electrodynamics and I don't think I was even aware of the basics of QM.

One day I decided, "I have to resolve this! I need some paradigm to imagine just to appease my curiosity!". At this point I was no longer concerned so much about being right as I was about just thinking of some way to picture it, just some allegory that made a shred of sense in my own mind.

What I came up with was a lot like the space-time warping some people here have talked about in the context of string theory. At the time the only thing I knew beyond Newtonian mechanics was a qualitative understanding of general relativity. So I just decided to think of the same thing as a mass distorting space-time except that there were two entities which would distort it in "opposite directions".

I thought of it kind of like one distorts the fabric inwards and the other distorts it outwards. To simplify the picture in my head I thought of it like single waves. One was a single crest and the other was a single trough. The crests were space-time ballooning out, the troughs were ballooning in (if that makes sense). If a crest meets a trough then they cancel out and the amount of "fabric" between them decreases, or they attract. If two of the same meet then they amplify each other and the separation grows, or a repulsion.

These days when I imagine that is isn't as satisfying as it was years ago. There are problems like the issue of two crests superimposing. This may separate the entities but it would do so by some specific amount (the sum of their distortions), which would imply that the force would suddenly stop when they were that far apart unless another like charge entered the system. Also, if it is actually space-time that they are distorting then wouldn't any other object, charged or not, be effected and hence appear to to experience the "force" as well?

So clearly it had lots of problems, but that's how ideas in physics work. Wonder, imagine a model, calculate its implications, compare those with reality, repeat.

***

These days, while I have not yet formally studied QED I can somewhat use it to create a little "artists rendition" of the EM interactions in my minds eye which keeps me happy enough for now.

All in all I think you should never tell someone there is no answer. You can't be sure of that anymore than they can be sure that there is an answer, and in the end trying to think of a better explanation will always have a slight chance to actually get you somewhere. If you don't try than you are guaranteed to never make progress.
Zhabka
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#47
Aug25-10, 04:57 PM
P: 18
But I suppose we shouldn't feel too bad, even the great minds of the Juggalo community are at a loss to explain this phenomenon! Fortunately good old Mr.Feynmann came to their rescue too.

http://www.youtube.com/watch?v=pDN1W...eature=related
JustRosy
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#48
Jun13-11, 07:09 PM
P: 1
Just a theory. I'm certainly no scientist. I'm sure at least some of what I'm saying here is off in some way or another, but I wanted to take a crack at this anyway.

Do you remember playing a game, probably as a child, where you had a sealed plastic box with a clear top, and inside the box was a plane of holes just above it's bottom, and in one side, were small metal balls which were held away from it, and then released into it? The object of the game was to get all the balls to sit in all the holes. It was harder than it looked, but it could be done, with time and concentration.

I like to look at positive, negative, and neutral charges that way. The charges desiring to be neutral (yet they may at first be either positive or negative) are the holes, the negative and positive charges are the small balls. When you release the balls to roll over the holes, especially at first, most of the balls will be "attracted" to the holes (so long as the box is right side up, of course). The amount of gravity is about the same, regardless of whether there is a hole in the plane or not, but because the balls "fit" into the holes, and because the pull of gravity is inevitably downward, when a ball's path is "disturbed" by the existence of a hole of at least an equal size and shape, with the need for the fit of a particular ball (charge) of at the most an equal size and shape, the ball "falls" into the hole. Gravity can be blamed for this, to some degree, but it would be interesting to see how this game would work in a vacuum. Anyway, the holes themselves do have some influence on the paths of the balls.

This "attraction" is because of a natural need for balance, or neutrality. Balance seems to be almost a requirement of both mother nature and human nature. "Equal and opposite forces..." etc. What do stars do? They try to balance, and spend their lifetimes, even their "after lives" trying to attain it. True balance, of course, means nothingness, from whence nothing can return - and yet nothing is lost, or gained, on any easily measurable level. In the human realm, losses are often converted to gains, the proverbial "lemonade."

Another way to look at it is that every negative charge is in need of another negative charge to be "complete." Negatives "fit" each other, creating positives, and if too many negatives are attracted, this can attract more negatives to fill the holes to create a neutral charge. If no extra negatives are created, some can be lost as positives are "damaged" or split in the process, thus attracting more damaged positives to remove the excess negative charges to fill their own "holes." Positive charges only need to loose a negative charge when split or when introduced to one too many negative charges. They'll do whatever possible to achieve this needed balance, when it's possible. You can also see this in human nature, so it stands to reason that human beings are made up of atomic structures which operate in the same manner, in order to perform varying functions throughout the human body, which give way to processes that create who we are as people.

Here's a question: Does everything, from atoms to galaxies and beyond, spin in the same direction? If so, or if not, why?
Nosh37
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#49
Sep22-13, 07:50 PM
P: 1
I like where Just Rosy is going with the ball idea. The universe is run on energy I would assume. And because it runs on energy you need to understand ideas of both kinetic and potential energy. Something that is positively charged does not become stable until it is attracted to something negatively charged just like particles in higher densities go to particles in lower densities. The idea of positive and negative charges is almost misleading in this context. It is simply the idea of a property brought on by protons and electrons. Protons and electrons are attracted to each other because it provides stability to the universe. If the universe had no inclination to be stable, I seriously doubt humanity would even be around to answer that question. So be thankful that positive attracts to negative, because it is important.

Just Rosy here is an answer: probably not. Have you heard of the different half spin properties of electrons? You know the property that makes atoms paramagnetic, diamagnetic, and ferromagnetic?
jarekd
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#50
Sep23-13, 07:38 AM
P: 111
The repulsion/attraction of the same/opposite charges (and quantization) is natural if we see them as being of topological nature - if they are just topological charges. Then we can easily get to Maxwell equations describing their behavior (thread).
The energy of the field grows with its stress. The top picture below shows that the closer opposite topological charges are, the smaller stress of the field (energy) - they attract:
Fiziqs
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#51
Sep23-13, 09:34 AM
P: 119
At the risk of once again being overly simplistic and stupid, I'm going to suggest a very simple way of explaining the attraction and repulsion of particles. Particles spin. Ta-da!!!!!

Like spinning tops, particles spinning in the same direction will violently repel each other, and particles spinning in opposite directions will be drawn together.

Now everybody feel free to point out why this explanation is incorrect. I have found that I can actually learn quite a bit by coming up with a simple way of visualizing something, and then having people much smarter than me tell me why I'm completely wrong. So feel free to point out my error.

Why can't a simple thing like spin, explain the attraction and repulsion of particles?
jarekd
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#52
Sep23-13, 09:39 AM
P: 111
Fiziqs, you are getting dipole moments this way, while charge is a monopole.
The difference is that while monopoles attract/repel with force proportional to 1/r^2 and it doesn't depend on their orientation ... monopole-dipole (like spin-orbit) interaction is 1/r^3, dipole-dipole 1/r^4 (e.g. making ortho-postronium much more stable than para) and they depend on relative orientation.
Fiziqs
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#53
Sep23-13, 01:57 PM
P: 119
Quote Quote by jarekd View Post
Fiziqs, you are getting dipole moments this way, while charge is a monopole.
The difference is that while monopoles attract/repel with force proportional to 1/r^2 and it doesn't depend on their orientation ... monopole-dipole (like spin-orbit) interaction is 1/r^3, dipole-dipole 1/r^4 (e.g. making ortho-postronium much more stable than para) and they depend on relative orientation.
Ok, after taking some time read up on the terms in this post I must admit that it is still going over my head. Is there any way to dumb this down? I realize that the post is probably self explanatory to most people here, but unfortunately I'm a little slow.

For example, I'm not sure what you mean when you state that charge is a monopole, or even what dipole moments are really.

Any clarification would be helpful, thanks.
jarekd
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#54
Sep23-13, 02:11 PM
P: 111
It means that electric field around charge (generally: monopole) is spherically symmetric: arrows direct toward or outward the center.
In contrast, dipoles are asymmetric exactly like bar magnet - emphasize some direction: http://en.wikipedia.org/wiki/Magnetic_dipole
Both spin and rotation/spinning of a charge correspond to magnetic dipole moment - beside being a charge, electron is also a tiny magnet: http://en.wikipedia.org/wiki/Electro..._dipole_moment


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