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## Question about the existence of "Charge"

 Quote by arul_k I am not familiar with Lagrangian equations, but in my very first post I did concede that mathematically the concept of charge is required.
In science we make mathematical models called theories. We then use those mathematical models to make a hypothesis, which is a predicted outcome of a specific proposed experiment. We then run the experiment and see if the outcome matches the hypothesis. If it does, then we call the mathematical model "verified" or "confirmed" and we have evidence to believe that the various mathematical objects in the model represent an accurate description of nature within the domain of the experiment.

The concept of charge was originally developed for a theory called Maxwell's equations, and has been since carried over as a central concept of a theory called Quantum Electro Dynamics. QED is the complete modern description of all electromagnetic phenomena. It explains all EM phenomena observed to date. It has been experimentally verified to greater precision than any other theory ever conceived or tested.

Charge is not only a mathematical concept, it is a mathematical concept with more exquisite experimental validation than any other concept ever developed. If you want something other than that then you are looking beyond the boundaries of science and the discussion doesn't belong here.

 Quote by arul_k Is it necessary to have a concept of charge apart from mass and electric field? What I mean to ask is for example in the case of an electron, it can be consisdered to have mass and a negative electric field, where is the need to introduce the concept of charge? mathematically it may be necessary to quantify charge but then is charge only a mathematical concept?
You'll be taking a lot of beatings for this thread in this forums.
I have never found the answer to my question, 'what is charge'?
It has no mass, it can not exist by itself, it always need a carrier. What is it?
I do not know if 'field' is the answer to my question. But it is a proposal worth looking into.
We can say 'field' is quantized for multiple charges, we can use imaginary lines of force in the fields for positive and negative fields as we do now.

I understand a 'field' must have a 'source', according to our current understanding of nature. Why don't we associate a 'charge like' concept with gravitational field also instead of only mass? We can call it 'Garge' or 'Gharge' etc, embedded in the mass which is causing gravitational field.

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 Quote by Neandethal00 You'll be taking a lot of beatings for this thread in this forums. I have never found the answer to my question, 'what is charge'? It has no mass, it can not exist by itself, it always need a carrier. What is it? I do not know if 'field' is the answer to my question. But it is a proposal worth looking into. We can say 'field' is quantized for multiple charges, we can use imaginary lines of force in the fields for positive and negative fields as we do now. I understand a 'field' must have a 'source', according to our current understanding of nature. Why don't we associate a 'charge like' concept with gravitational field also instead of only mass? We can call it 'Garge' or 'Gharge' etc, embedded in the mass which is causing gravitational field.
Charge is a property, like mass and spin. It is something that particles simply have that causes them to react in a certain way to another charged particle that has charge. We don't have a charge in gravitation because we have already accounted for gravitational interactions through mass and energy. More mass means a greater force exerted, whereas in electromagnetism more charges means a greater force.

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I just wanted to pop in and second what Simon Bridge said before (my bolding):
 Of course, bottom line is that these are all just models which we use to predict phenomena in nature. When the model does very well we tend to think we understand the phenomena. If you are not careful it will boil down to how you know that anything is real.
I did not want to second that because of the OP's question or because of the topic, I wanted to second it because there is very much truth in that in general, in my opinion. And it's one of the best statements I've seen on this forum, thumbs up!

 Quote by DennisN I just wanted to pop in and second what Simon Bridge said before (my bolding): Of course, bottom line is that these are all just models which we use to predict phenomena in nature. When the model does very well we tend to think we understand the phenomena. If you are not careful it will boil down to how you know that anything is real.
I also agree with this statement.

 Charge is a property, like mass and spin. It is something that particles simply have that causes them to react in a certain way to another charged particle that has charge. We don't have a charge in gravitation because we have already accounted for gravitational interactions through mass and energy. More mass means a greater force exerted, whereas in electromagnetism more charges means a greater force.
Aren't we following a double standard here? For electric field we use a strange 'property' calling it charge not mass, but for gravitational field we do not use a similar 'property' but use mass. All this because mathematical treatments satisfy observations.

Simon's statement above hits the bull's eye. Anyway, I guess we have to live with this.

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 Quote by Neandethal00 Aren't we following a double standard here? For electric field we use a strange 'property' calling it charge not mass, but for gravitational field we do not use a similar 'property' but use mass.
What double standard do you think exists?

Roughly speaking, there is an EM interaction governed by a property called charge and a gravitational interaction governed by a property called mass. There seems to be no double standard to me.

 Aren't we following a double standard here? For electric field we use a strange 'property' calling it charge not mass, but for gravitational field we do not use a similar 'property' but use mass. All this because mathematical treatments satisfy observations.
I think this is an excellent observation. Indeed there are (at least) two definitions of mass. One is so called inertial mass and is defined by Newton's second law, F = ma. The other is called gravitational mass and is defined by Newton's law of universal gravitation. These two are equal. This equality is one of the things that lead Einstein to his theory of general relativity.

 Quote by Neandethal00 You'll be taking a lot of beatings for this thread in this forums..
That happens to be the case for most of my questions!!!!!!!!
 Quote by Neandethal00 I have never found the answer to my question, 'what is charge'? It has no mass, it can not exist by itself, it always need a carrier. What is it? I do not know if 'field' is the answer to my question. But it is a proposal worth looking into. We can say 'field' is quantized for multiple charges, we can use imaginary lines of force in the fields for positive and negative fields as we do now. I understand a 'field' must have a 'source', according to our current understanding of nature. Why don't we associate a 'charge like' concept with gravitational field also instead of only mass? We can call it 'Garge' or 'Gharge' etc, embedded in the mass which is causing gravitational field.
Maybe the asumption that field must have a surce is false. As I stated earlier an EM wave once generated can exist independent of any "source"

Quote by DennisN
I just wanted to pop in and second what Simon Bridge said before (my bolding):

 Of course, bottom line is that these are all just models which we use to predict phenomena in nature. When the model does very well we tend to think we understand the phenomena. If you are not careful it will boil down to how you know that anything is real.
I did not want to second that because of the OP's question or because of the topic, I wanted to second it because there is very much truth in that in general, in my opinion. And it's one of the best statements I've seen on this forum, thumbs up!
Jul14-12 03:40 AM
There was a time when all of space was thought to be enveloped in what was known as the luminiferous aether. Was it "real" or was it "imaginary"? It just didn't exist. The concept was found to be redundant. The very basis of science is to enquire into the nature and origin of the phenomena we see around us.....

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 Quote by arul_k Maybe the asumption that field must have a surce is false. As I stated earlier an EM wave once generated can exist independent of any "source"
Even for an EM wave the Lagrangian has conserved quantity corresponding to the gauge symmetry. This conserved quantity is charge, and is still conserved even when its value is 0.

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 Quote by arul_k There was a time when all of space was thought to be enveloped in what was known as the luminiferous aether. Was it "real" or was it "imaginary"? It just didn't exist. The concept was found to be redundant. The very basis of science is to enquire into the nature and origin of the phenomena we see around us.....
Absolutely. But the luminiferous aether failed to show up AND it was not needed. Electric charge, on the other hand, shows up AND is needed (at least today).

If you are wielding Occam's Razor carelessly, you might find yourself trying to cut away things which to our current understanding have been verified and are needed. And then you will be going backwards in science. But, as I said, I only seconded Simon Bridge's statement because I think it was true and very well formulated in general, not because of the OP/topic, and I don't want to put my words in his mouth.

Concerning the existence of charge as we know it today, you have already got a lot of good answers from others. I will present the following for you to think about:

Particles in a magnetic field (Lorentz force)
Experiments have shown that there is a fundamental, elementary charge, e (disregarding fractional quark charges; they are confined). When charged particles travel through a magnetic field, particles with positive charge will turn one way, particles with negative charge will turn the other way and neutral particles will travel straight ahead. The path will be dependent on both the sign and the size of the charge. How would we model this without the concept of charge?

Annihilation/Pair production
Two electrons can not annihilate nor be the result of pair production; both processes involves an electron and a positron. How would we model this without the concept of charge and charge conservation? Or, to put it in another way, how could we tell the difference between matter and antimatter without the concept of charge? (compare with your suggested EM-waves; two EM-waves will NOT annihilate; they will pass right through eachother)

Standard Model
How do you build/rebuild the Standard Model without the concept of charge? (that's a tough one)

It seems Occam's Razor is up against some really serious non-redundancy in the case of electric charge.
Note: Please don't take this as a beating. It is just meant to show the significance of what you are questioning.
 Recognitions: Gold Member Science Advisor This thread contains a lot of suspect 'messing about' with already well-defined quantities. How can anyone confuse Field with Charge? A field is a vector, for a start, and a charge is a scalar. That makes them about as different as they could be. A field can exist in between two charges or 'around' one charge but that doesn't make the two things the same.