I have read many books for laypeople yes, I was a layperson once myself, and I remember, at the age of 16, reading about this stuff Electrodinamica cuantica yahoo dating all of them talk about virtual particles and not one of them has ever Electrodinamica cuantica yahoo dating any sense to me. So I am going to try a different approach in explaining it to you. A virtual particle is not a particle at all. It refers precisely to a disturbance in a field that is not a particle.
A particle is a nice, regular ripple in a field, one that can travel smoothly and effortlessly through space, like a clear tone of a bell moving through the air.
If you give it a shove and let it go, it will swing back and forth with a time period that is always the same, no Electrodinamica cuantica yahoo dating how hard was the initial shove you gave it.
This is the natural motion of the swing. Well, the swing would start jiggling around all over the place, in a very unnatural motionand it would not swing smoothly at all. If something makes a real particle, that particle can go off Electrodinamica cuantica yahoo dating its own across space. If something makes a disturbance, that disturbance will die away, or break apart, once its cause is gone.
Two electrons approach each other; they generate a disturbance in the electromagnetic field the photon field ; this disturbance pushes them apart, and their paths are bent outward. One says they "exchange virtual photons", but this is just jargon.
For example, an electron is a real particle, a ripple in the electron field; you can hold one Electrodinamica cuantica yahoo dating cuantica yahoo dating your hand, so to speak; you can make a beam of them and send them across a room or inside an century television set a cathode-ray tube. A photon, too, is a real particle of light, a ripple in Electrodinamica cuantica yahoo dating electromagnetic field, and you can make a beam of photons Electrodinamica cuantica yahoo dating in a laser.
But if two electrons pass near each other, as in Figure 1, they will, because of their electric charge, disturb the electromagnetic field, sometimes called the photon field because its ripples are photons. That disturbance, sketched whimsically in green in the figure, is not a photon.
That said, it is not at all mysterious; it is something whose details, if we know the initial motions of the electrons, can be calculated easily. As in Figure 1, for a positron an anti-electron and an electron; now the slightly different disturbance causes the two particles to attract one another, and their paths are bent inward. This disturbance is important, because the force that the two electrons exert on each other — the repulsive electric force between the two particles of the same electric charge — is generated by this disturbance.
The same is true if an electron and a positron pass each other, as in Figure 2; the disturbance in this case is similar in type but different in its details, with the result that the oppositely charged electron Electrodinamica cuantica yahoo dating positron are attracted to each other. To really understand this you need a small amount of math, but zero math is unfortunately not enough.
An electron may naively be thought of as a ripple of minimum intensity the minimal ripple in an electron field. But the electron interacts with the photon field i. The combination of the two disturbances i. Now there are many types of disturbances that fields can exhibit that are not particles. Another example, and scientifically one of the most important, shows up in the very nature of particles themselves.
A particle is
Electrodinamica cuantica yahoo dating as simple as I have naively described. It turns out that since electrons carry electric charge, their very presence disturbs the electromagnetic field around them, and so electrons spend some of their time as a combination of two disturbances, one in in the electron field and one in the electromagnetic field.
The disturbance in the electron
Electrodinamica cuantica yahoo dating is not an electron Electrodinamica cuantica yahoo dating, and the disturbance in the photon field is not a photon particle. This is sketchily illustrated in Figure 3. The Feynman diagram needed to calculate the process in Fig. One says electron emits and reabsorbs a virtual photon", but this is just shorthand for the physics shown in Fig.
The language physicists use in describing this is the following: As in Figure 3, for a photon. The Electrodinamica cuantica yahoo dating can become a disturbance in the electron field. This disturbance has some regions with negative electric charge and some with positive electric charge, but with total charge zero, like the incoming photon itself.
The photon can do the same with other charged fields, such as the muon field. Another example involves the photon It is not merely a ripple in the electromagnetic field, but spends some of its time as an electron field disturbance, such that the combination remains a massless particle.
The language here is to say that a photon can turn into a virtual electron and a virtual positron, and back again; but again, what this really means is that the electron field is disturbed by the photon. But why are we seeing a positron — an anti-electron — and yet I am only referring to the electron field? The reason ties back to the very reason that there are anti-particles in the first place: For some fields such as the photon field and Z field these particle and anti-particle ripples are actually the same thing; but for fields like electrons and quarks, the particles and anti-particles are quite different.
So what happens when the electron field is disturbed by a passing photon is that a disturbance is set up that has some electron-like disturbance with net negative electric charge, and some positron-like disturbance with net positive charge, but the disturbance as a whole, Electrodinamica cuantica yahoo dating the photon itself, carries no net charge at all.
For those who learned and recall a bit of freshman physics, what is happening is that the oscillating electric Electrodinamica cuantica yahoo dating that makes up the photon is polarizing the electron field — inducing a dipole moment.
Remember dielectrics and how electric fields can polarize them? One "photon becomes a virtual electron-positron pair", but this is just shorthand for the physics shown in Fig. The same is true, by the way, for all the other electrically charged fields, including those of the muon, the up quark, and so forth.
I have had several people Electrodinamica cuantica yahoo dating me something like this: Virtual particles, which are what appear in the loop in that diagram, are not particles. They are not nice ripples, but more general disturbances. And only particles have the expected relation between energy, momentum and mass; the more general disturbances do not satisfy these relations.
So your intuition is simply misled by misreading the diagram. Instead, one has to do a real computation of the effect of these disturbances. In the case of the photon, it turns out the effect of this process on the photon mass is exactly zero. The Electrodinamica cuantica yahoo dating can generate disturbances in the photon field; the resulting photon disturbance can in turn create disturbances in other electrically charged fields, such as the muon field.
And it goes on from there. Our picture of an electron in Figure 3 was itself still too naive, because the photon disturbance around the electron itself disturbs the muon field, polarizing it in its turn. This is shown in Figure 7, and the corresponding Feynman diagram is shown in Figure 8. This goes on and on, with a Electrodinamica cuantica yahoo dating in any field disturbing, to a greater Electrodinamica cuantica yahoo dating lesser degree, all of the fields with which it directly or even indirectly has an interaction.
The Feynman diagram needed to calculate the process shown in Figure 7. But sometimes these complications are central, so we always have to remember they are there. Is it correct to say that these quantum fields pervade spacetime — or is it better say the set of fields actually composes creates?
Also, what is the complete list of fields currently known? In most theories with extra dimensions, some of the fields that we observe would actually form a part of the metric Electrodinamica cuantica yahoo dating the higher-dimensional spacetime. In other words, one explanation as to why there Electrodinamica cuantica yahoo dating so many fields in nature might be that we live in a world that has some of its dimensions wrapped up think of how a hose has a large dimension along the hose and small dimension around the hose and that the metric of the full space-time looks to us, in three-dimensional space, like a metric for three-dimensional space and time along with many other fields whose explanation seems non-obvious.
A complete list of fields is ill-defined, but I can give you the list of apparently-elementary fields. And Electrodinamica cuantica yahoo dating wind field and temperature fields in air, a density field in a metal, are composite too. I did not find consensus in this one. As long as you understand the object does not correspond to any concept in English or in daily life, and that it has some properties that you just have to learn about, you can call an electron an elementary particle, a quantum of the electron field, or a quantized wave in the electron field.
Elementary particle is rather short and the least mysterious sounding. Just that many experiments on the basic properties of nature require studying its particles, if you do those experiments, propose them, study them, interpret them, etc. Not all fields have particles, while all particles are quanta of
Electrodinamica cuantica yahoo dating. Then a massive particle is a localized object with a definite mass, energy, momentum and position, and orientation.
I can now a representation of the Poincare group — the group of all translations, rotations, and changes of reference frame
Electrodinamica cuantica yahoo dating with a constant velocity — by simply moving the particle to a new position, rotating the particle, or looking at the particle Electrodinamica cuantica yahoo dating a different frame.
That set of particle states with all those different positions, orientations, and velocities form a complete representation of the Poincare group. But I can do a pretty good job on both, or a perfect job on either one.
In dense aether theory the water surface can serve as a low dimensional analogy of 4D space-time and the density fluctuations of the underwater are the analogy of virtual particles, after then.
So what you are saying essentially is that transient ripples, which are not stable or sustainable, are caused by
Electrodinamica cuantica yahoo dating particle in every other field with which they can interact.
If another particle is present, their ripples combine and the particles DO interact. They fall apart, into Electrodinamica cuantica yahoo dating particles. For example, if the two electrons in my picture came together with enough energy, the transient ripple Electrodinamica cuantica yahoo dating in the figure could have enough energy to produce an electron-positron pair so that there would be four particles in the final part of the picture, three electrons and a positron.
The disturbance in the field can carry lots of energy, and that energy can be turned into particles. But the disturbance itself Electrodinamica cuantica yahoo dating still transient. Does that answer the question? The original asker seemed to purport this. One of the things that tripped me up as a student, was also just how arbitrarily small you could make the difference between real and virtual.
But then every particle we have ever Electrodinamica cuantica yahoo dating is an internal leg of a bigger Feynman diagram. For instance, the electron we measured from a particle accelerator eventually is absorbed by an atom somewhere, and hence becomes an internal leg in that diagram. So then most people say, well its just a question of lifetime.
Long lived particles called real, short lived particles are virtual.
But then suppose you have a photon that was emitted from the Pleiades, and it presumably is real or almost real all the Electrodinamica cuantica yahoo dating cuantica yahoo dating until it is absorbed in your retina.
So have you just measured a real or virtual photon? sorta depends on how you draw the diagram! In general, what we have in quantum fields are disturbances of many types. There is a very special disturbance we may call a particle, which is a ripple can in principle travel forever.
But this is an idealization: So the issue is how close is it to the ideal case. In most physical processes one deals
Electrodinamica cuantica yahoo dating Electrodinamica cuantica yahoo dating that are clearly either close to the ideal or very far from the ideal.