Why should like charges repel and unlike charges attract? What is the theory behind it?

Question

I want a deep answer...

Answer 1

All fermions exchange virtual bosons with all other fermions.

I'm going to state the obvious now. The only reason you can detect an electron is because of its effect on its surroundings. What can you detect? There are only three ways in which an electron can be detected:

1) Electrostatically (like charges repel, unlike charges attract - just like in your question).
2) Gravitationally (this is a very weak force but is more well known than number 3, so I've included it here).
3) Quantum Mechanically (according to fermi-dirac statistics, two electrons cannot occupy the same quantum state, so there is a strong repulsive force between two electrons of the same quantum state. This is a little complicated to explain so I'll go into more detail below (for completeness).

Let's deal with the electrostatic case first. How does one electron know that there is another electron nearby? Like I said earlier, all fermions exchange virtual bosons with all other fermions. A fermion is a particle with a half-integer net intrinsic spin that obeys fermi-dirac statistics. A boson is a particle with integer net intrinsic spin that obeys bose-einstein statistics. This means that, whilst bosons can occupy identical quantum states, fermions cannot.

Now, the most common boson is the photon (often described as 'the particle of light'). Virtual bosons are so called because bosons are created (yes, created: violating conservation of energy) by a fermion and 'given' to another fermion. The boson then ceases to exist (yes, the virtual boson is destroyed: again violating conservation of energy).

In the case of an electron's charge, the virtual boson is the virtual photon. The virtual photon is created by a fermion, travels at the speed of light to another fermion and then exchanges its momentum with it. Then, the virtual photon ceases to exist. Now, this is important to note, the phase of the photon determines whether the momentum exchange is positive or negative. The phase of the virtual photon emitted is what determines our labelling of 'charge' as being 'positive or negative'.

If an electron exchanges a virtual photon with another electron the second electron experiences a force away from the first electron. Remember, though, that the second electron at the same time will exchange a virtual photon with the first, so the first photon will also move away from the second. It is all due to the exchange of momentum of the virtual photons and, technically speaking, violates conservation of energy.

Conservation of energy is only conserved in the principal of equivelence (that if you take the average of a quantum mechanical system over a sufficiently large time, it will behave like a classical system). Heisenburg's uncertainty principal dictates that energy can be created and destroyed as long as it is for sufficiently short amounts of time. This is dictated by the equation:

ΔE Δt ≥ ħ / 2

where ΔE is the change in energy (either created or destroyed, positive or negative), Δt is the amount of time over which the energy change occurs and ħ is the reduced planck's constant. This is not a fairy tale or make-believe: this is FACT, proven by the workings of a LASER or by the existance of alpha decay. It forms the basis for quantum field theory.

If you are convinced that energy can be created and destroyed as long as Heisenburg's uncertainty principal is obeyed, repulsion should make perfect sence. So what about electrostatic attraction (the attraction of two opposite charges)?

Well, if we consider a positron (the anti-electron) it has a +1 quantum electrical charge. This means that it emits virtual photons π radians out-of-phase. This means the momentum exchange is in the opposite direction, so the two particles (the electron and the positron) will feel a net force towards each other.

And that is exactly why like charges repel and unlike charges attract.

Now, gravitational attraction is believed to be caused by the idea but, instead of a virtual photon being exchanged, a virtual 'graviton' is exchanged. This is the theory adopted by super-string theory. Other theories include the Higg's field (which is more closely related to general relativity than quantum field theory).

Now, I said earlier I would explain about the 'size' of an electron. In quantum mechanics, the electron cannot be considered to be a particle in the same sence as in classical physics. In quantum mechanics, a particle as defined as the region over which the probability density function of the 'particle' is greater than the full-width at half-maximum (FWHM) value. This is because, according to Heisenburg's uncertainty principal, the exact position and momentum of a particle cannot be known. For this reason, rather than say a particle exists at a specific point in space, quantum mechanics relys on the use of a probability distribution function (pdf). Quantum tunnelling occurs because the pdf of a 'particle' changes at the 'walls' of a 'quantum well'.

Now, at this point I could go into an eight-week lecture series about how quantum mechanics works, so I will stop. But, it should be clear to you that the electron, when considered in quantum mechanics, exists in a pdf.

I also said I would come back to the force exerted on fermions of the same quantum state. Charge is an example of quantum state (at a simple level it can have three values: -1, 0 or 1). There also exists the quantum states of angular momentum, spin and, or coarse, the principal quantum number 'n'. These quantum numbers are labels that describe how the electron exists with respect to other particles. Two particles with the same quantum numbers cannot exist in the same position at the same time. Now, because in the orbits of an atom (for example) electrons can only exist in well-defined bands of states, there will be times when two identical electrons have the opportunity to occupy the same state. When that happens, one of the electrons changes state. In some cases the lowest-energy state change is to a higher 'n' value. This is yet another example of a breakdown in conservation of energy but is explained by quantum field theory beautifully (the energy is borrowed from the quantum field and replaced afterwards in such a short time that Heisenburg's uncertainty principal isn't violated). Importantly, the electron may jump up a state and the down again into a different state. When it does, it emits a photon (the excess energy).

Quantum mechanics is full of examples of how conservation of energy is violated.

In conclusion, the answer to your question, "Why should like charges repel and unlike charges attract?" is:

The repulsive and attractive force felt by charged particles is due to the momentum exchange of the virtual photons and depends on thier phase.

Answer 2

Electrons are formed of three factors. there is the mass comprising the southern a million/2 (gives you resistance to circulate), there is the electrical powered equator that bonds the electron and keeps it bonded, and there is the increasing magnetic lines of the northern a million/2 that equivalent the mass of the southern a million/2. simply by fact the capability of the magnetic lines equals the mass of the southern a million/2, a guy or woman is able to work out that there are sturdy lines of effect achieving outward from an electron. The magnetic lines being proportional to the southern mass have an instantaneous effect on the whole electron (like the version between towing a automobile with a rope or heavy chain). those lines of rigidity strengthen far previous the electron and, additionally, at oblique angles to path of shuttle, so as that they take in diverse "area". What reasons electrons to repel one yet another is the path of magnetic lines. all of them spin counterclockwise, so while they meet shifting from opposite guidelines, they lines on an identical time repel one yet another over long distances.

Answer 3

This was already answered on YAHOO ...try here

http://in.answers.yahoo.com/question/index?qid=20061106060503AAkbIfa