All light comes from electrons that are in atoms. All light comes in the form of photons. All photons are 30 centimeters long. Tney consist of bits. There are negative bits and positive bits. They are emitted as pairs. I call them neg-pos pairs. As a photon is emitted, the pairs leave one behind another. If the first pair is oriented neg-pos, the next pair is oriented pos-neg. Thus they alternate. The distance between two pairs of similar orientation is the wavelength. The number of wavelengths in a photon is the frequency of that photon.
The key to understanding how photons are emitted is the behavior of an electron in an atom. The simplest atom is the atom of hydrogen. It has one proton and one electron. The electron is at a small distance from the proton. It can happen that an electron receives a strong push from an intruding body. If that push is toward the proton, the electron moves toward the proton, but does not quite reach it because there is a repelling force that increases as the distance shortens. The motion of the electron stops. Then it moves outward toward the point where it began. It overshoots, passing the central point at its highest speed. Thereafter, on the way out, the attraction causes the motion to slow to a halt, after which it moves back to fly past the central point again. That is oscillation. I call the central point the point of zero net force. If the oscillation stops, the electron comes to rest at its point of zero net force.
The oscillation of an electron would continue forever, if it did not lose some of the neg-pos pairs. Since the electron starts to lose motion at the instant that it passes the point of zero net force, it emits one pair for each passing, also known as "half cycle".
In atoms other than hydrogen atoms, the point of zero net force is determined by the algebraic sum of the forces from the nucleus and the other electrons. Therefore the frequency of the light emitted by atoms of different elements is characteristic of each element. Each element can be identified by its spectrum. The amplitude of the oscillation that is of relatively low frequency, say red, is less than the amplitude of oscillation for a higher frequency, say violet. The electron moves faster when it is pushed harder. But the electron has a longer way to travel when it is pushed harder. The result is that the frequency of oscillation for red is constant throughout the process of emitting a red photon. The expanation for that is that the force inreases at a constant rate as the path gets longer.
There is a limit to how hard you may push the electron and still get red light from it. At the limit, the rate of growth of restoring force is greater. For the zone in which the force increases faster, the electron covers the distance in less time, therefore has higher frequency.
The importance of this essay is in its contradiction of theories now accepted by the majority of scientists. They believe that the electron that emits the highest frequency loses its motion by dropping from the first allowable level above the zero level, to the zero level. They think that red light is emitted by an electron that drops from a level like 4 to a level 3, from which the electron can drop even lower and emit electrons of higher frequency.
Now that we have the experience with ruby lasers in which the red light is emitted when the electron is dropping to its lowest possible level we have evidence that the accepted theory is not in agreement with observation.
According to the textbooks, the electron in the hydrogen atom jumps from zero to 1 with an energy of an ultraviolet photon. When more energy is absorbed by the electron, it can rise to levels 2 and 3 and more. (limited only to the point at which the electron has escape energy) When the level rises to the range of visible light, after violet comes blue, green. yellow, etc. Notice that the electron cannot absorb red before it has absorbed six other colors of the spectrum plus ultraviolet.
Evidently, the experimenter never tried to find the absorption of monochromatic red light. If he did, he would find that the energy of the electron is at a low level when a red photon is absorbed. Naturally, when the entire spectrum is absorbed at once, red will be included, and you can't tell whether the more energetic photons had to get there first.
According to quantum theory, the electron in an atom is never at rest. No attempt is made to explain what makes the electron move. Supposing that the electron always moves, how can we express the location of the electron? The trick is to compute the probability of finding the electron at a point. Of course they mean an infinite number of points. Even if it were about a few points, how can one explain the unchanging energy in a particle whose motion is always changing? It gets a bit more complicated when two electrons share one set of probabilities. And when a photon is absorbed, what is the location of highest probability of finding the electron?
Wonders never cease. When the electron in an atom emits a photon, they say that the electron makes an immediate drop from one energy level to another. In that instant, the emitted photon comes into existence and flies off at the speed C. If the photon spends no time being formed, and wastes no time accelerating to speed C, it must be the size of a submicroscopic dot. Why then do they say that the photon has wavelength and frequency?
Now you see how you can learn from a laser what a photon is really like. It takes a billionth of a second to emit a photon. The front end of the leaving photon travels 30 centimeters before the rear end leaves. The frequency of the photon is exactly the same frequency as the frequency of the electron that emits the photon. The energy of the photon is equal to the energy loss of the electron. The photons that are emitted by a laser are exactly in step.
Incidentally, only certain atoms are capable of emitting photons in concert with other photons (synchronized). Those atoms must be capable of delaying the process of emission for a while, even though it is a short interval. When the photon from one atom, of say chromium, passes close to another chromium atom, which is in the excited state, it triggers the emission of a photon that is in step with the first photon. Naturally, there is a slight lag in takeoff, causing the first cycle of the second photon to be slightly behind that of the first cycle of the first photon. The result is an uninterrupted ray of great numbers of photons that is, in effect, a continuous emission.
In some applications of a laser, the ray gets pulsed by interrupters. The light becomes fragmented. It is not in the form of photons, which always are 30 centimeters long. Nevertheless, the fragments can be received in succession by atoms whose electron respond as if they were receiving photons of that color. Anyway, radiations of many kinds are continuous, like microwave and radio, even though their structure is the same as that of photons.