Virtual Particles and the Speed of
[the following series of questions came in one email, but represent a number of similar questions]
Setterfield: The answer is basically yes. There are a number of other ways of looking at this, but that is a good picture.
Setterfield: Again the answer is bascially yes on this approach. You might consider that the speed of light has always remained the same, except for the interference from the virtual particles.
Setterfield: Yes. On this approach, the speed of a light photon between interactions with virtual particles has remained unchanged since the origin of the universe.
Setterfield: The answer is NO! The intrinsic impedance of the vacuum is fixed. This means that the electric and magnetic properties of the vacuum change synchronously. If only the electric property of space changed and the magnetic properties were fixed (or vice versa), there would THEN be dispersion. But this does not happen, and dispersion does not occur.
Setterfield: NO! it has nothing to do with the wave nature of light, nor does it contribute to it.
Setterfield: You are heading in the right direction here. The important key is that SED physics has shown that inertial mass on a subatomic level (such as with an electron) is due to the retarding force exerted by the waves of the Zero Point Energy (ZPE). As an electron is accelerated, it encounters an increasing number of waves which offer resistance to acceleration and so impede motion. This manifests as inertial mass. Thus, when an electron's mass increases, it is because there are more ZPE waves in a given volume. At the same time, this increased number of waves offers a greater resistance to the motion of the electron (or other subatomic particles) and so it travels more slowly. This is probably a better picture to present than one using virtual particles, as the virtual particle interaction you suggested would be (at the atomic level) an intermittent one, whereas the ZPE waves are acting against the electron continuously. However, your analogy using the swimming pool is good.
Setterfield: In answer to this question, it must be realized that we are not only dealing with electrons when masses increase with the resultant velocity decrease. The same is true of all sub-atomic particles including protons and neutrons. Let us here give the illustration of alpha decay. Picture the alpha particle moving back and forth within the nucleus of an atom that undergoes alpha decay. The alpha particle is constrained by the potential energy barrier of the nucleus. The motion of the alpha particle within the nucleus causes it to strike the barrier, or knock at the gate to be let out, a certain number of times per second. Each time it hits the barrier, there is a finite probability that it will penetrate the barrier and escape. When the ZPE is lower, subatomic masses are also lower, but their total kinetic energy is unchanged. This means that the speed of the alpha particles within the nucleus is higher, which results in more hits at the barrier per second, and so it escapes sooner. Conversely, as the ZPE strength increases, alpha particle masses increase and their velocity decreases. This means fewer hits per second at the barrier, and so a reduced escape rate results. This means that the rate of radioactive decay is also reduced.
Setterfield: There are several components to this question. First, we can only see something if light is emitted by that object, or if light is reflected off that object. For a lantern shining in the dark, we see it because light photons are emitted by the lantern in our direction. For a person walking down a hallway, light is reflected off that person in such a way that light photons are bounced back in our direction that allow us to see that person. In both cases, the light photons have to travel the distance from the emitter or reflector to the observer. For most purposes on earth, because the distances involved are so small, these light photons cover the distance almost instantaneously. In the case of the Moon, which we see because it reflects light from the sun back to earth, those reflected photons have to travel the distance from Moon to Earth and the process takes about 1.5 seconds. So light, radio and all electromagnetic radiation takes time to travel, even though the radiation travels exceedingly fast.
The second part of the question relates to why there is this time delay seeing that it is "empty space" that is being traversed. Iain effectively asks why it does not happen instantaneously because there is "nothing in the way" so to speak. It is at this point that the discoveries of modern physics comes to the fore. In the 18th century, a vacuum was thought to be just empty space devoid of all solids, liquids and gases. Then in the 19th century it was discovered that radiation such as heat could be transmitted through the vacuum. The idea was then to have a perfectly sealable flask, pump all solids, liquids and gases out of the flask and then cool it down to zero degrees Kelvin (absolute zero or about minus 273 degrees C) so that no temperature radiation existed within the flask. In the 20th century, it was discovered that even if that was done, and the flask was completely in the dark as well, then an energy still existed within that vacuum and was intrinsic to it. That energy is called the Zero Point Energy (ZPE) because it is there at absolute zero temperature, and it is pervasive throughout the whole universe, going through everything.It is in the form of electromagnetic fields and waves and originates with the stretching of the heavens (as the Bible states 12 times) or the expansion of the universe (as astronomers express it).
When you go down to a beach, and a speedboat goes by, the waves from the boat hit the waves from the ocean and form whitecaps where they meet. In the same way when the ZPE waves meet, they form a concentration of energy. Modern physics has established that energy and matter are inter-convertible. So at the point where the ZPE waves meet, virtual particle pairs form, which are positive and negative pairs of subatomic particles. So there would be formed electron-positron pairs or proton-antiproton pairs, or a positive and negative pion pair, and so on. The particle pair which formed would depend on the energy of the colliding waves. There is a whole zoo of such virtual particle pairs filling any given volume. Each pair only exists momentarily, but then the positive and negative charges attract each other, and they annihilate back to energy again. However fleeting their existence, they do have an effect on the properties of the vacuum. Indeed, it can be calculated that at any given instant, there are about 1063 virtual particle pairs in any cubic meter that we are dealing with.
Now consider a photon of light going through the "vacuum". It hits a particle pair, is absorbed, the pair annihilate and the photon is re-emitted and goes on its way, only to strike another virtual particle pair... In other words, the path of a photon through space is like a runner going over hurdles. The more hurdles there are between the start and the finish, the slower the elapsed time from the runners in completing the course. Alternately, it is like a very fast train having to make quick stops at a number of stations on the line. The more stops, the longer the train takes to get to its final destination.
So the vacuum is not "empty" but filled with virtual particle pairs. The number of pairs depends on the strength of the Zero Point Energy. Since the ZPE originated with the stretching of the universe, then, as the stretching went on, the ZPE strength built up. As a result, more and more virtual particle pairs came to exist in any given volume of space. So space became "thicker" with virtual particles as time went on. The conclusion is that light traveled extremely fast initially when the ZPE strength was low, but is now traveling much more slowly because of a higher ZPE strength and a vacuum which is "thicker" with virtual particles.
I hope that answers your question.