### Reflections On Refraction

When light comes in the window pane, its path shifts, but you must observe very closely to notice this. Automobile windshields used to be flat. Now they are curved, and the distortion at both ends of the glass is noticeable.

While we are examining window panes, we should pay attention to how much light is reflected at the near surface, and how much at the far surface. Then we can compare how much light is reflected at various angles.

It is often expedient to see what happens in extreme cases. In this instance we can get a block of glass, about the size and shape of a child's toy block. In a dimly lit room, place the block on a sheet of paper. Shine the narrow beam from a pen light or any flashlight that is covered except for a tiny hole in the light shield.

When the light ray is perpendicular to the surface of the glass, the ray passes through in a straight line. When the ray is at another angle, the ray bends sharply at the near surface of the glass, and bends again at the far surface. We obseve that the starting ray became shifted in passing through the glass, and then emerged parallel to the original ray.

We repeat the experiment using an opaque shield in front of the light source. There is a narrow slit in the shield, about as thin as a razor blade, for light to pass. The light bends at the near surface of the glass block. Inside the block, the ray widens. It becomes a spectrum, and when it exits through the far surface of the glass block, it displays all the colors of the rainbow.

White light contains photons of various frequencies. At each encounter of a photon with an electron, the path of the photon is slightly altered. There are fewer encounters in air because there is more empty space between molecules. In glass there are more encounters.

Furthermore, in glass the electrons are more uniform. The atoms in the glass are under the constant influence of their neighbors. In fact, there are only a few special electrons that can oscillate at frequencies near the frequencies of visible light photons. Their natural frequencies are in the ultraviolet range.

If the electrons in the glass could vibrate at the frequencies of visible light, the glass would lose its transparency. Some glasses contain an impurity whose frequency matches the frequency of certain photons of a particular color. That glass absorbs that color, causing the ray to lose its whiteness. The glass becomes colored.

Notice that we could not see the colors of the spectrum until we passed the light through a narrow slit. The photons in the ray of white light travel together until they begin to refract by different amounts according to color. If the beam of white light is wide, the ray receives as many photons from other sources as it loses by refraction. Therefore the ray remains white.

However, when the ray is narrow and far removed from other rays, each color in the ray bends by a different angle, causing the colors to separate from each other. The whiteness disappears.

When the path of the ray is perpendicular to the plane of the near surface of the glass, a photon that reaches an electron in the glass causes the electron to oscillate on a plane that is parallel to the surface. The first neg-pos pair of that photon determines the plane. When the neg-pos pairs are out of step with the oscillation of the electron, the electron emits pairs at the same rate as they arrive.

The incoming photon consists of neg-pos pairs that have mass and velocity. That combination is called momentum. Upon arrival at the electron, the first neg-pos pair stops short, losing its momentum. Momentum never disappears. It is transferred from one body to another. In this instance the momentum is taken up by the electron.

The electron is oscillating through a path that includes the point of zero force. That point belongs to the atom, whch, in turn, is strongly attached to its location in the glass. Therefore the path of oscillation is on a plane that shifts a little each time a neg-pos pair is retained.

When the electron begins to emit neg-pos pairs, the photon is refracted and pursues a path that is perpendicular to the new plane of oscillation.

It turns out that the frequency of the oscillation of the electron is in the ultraviolet range. When a photon of violet light reaches the electron, each neg-pos pair shifts the position of the oscillation plane exactly as much as the neg-pos pair from a red photon would. The difference is that the neg-pos pairs of violet arrive in more rapid succession, and more of them accumulate before the emission begins. Thus the angle of the plane of oscillation has shifted more. Of all the visible photons, the red photon collects least at the electron, and the angle of the oscillation plane shifts least for red.

While emision goes forward, the angle does not shift, because all of the newly arrived momentum is transferred to the departing neg-pos. Toward the end of the departure of the photon, the electron moves back to its original plane, to compensate for the restoration of momentum to the final neg-pos pairs.

There is a way of viewing the spectrum of white light without glass. Light from a point source is directed toward twin slits that are separated by a razor-thin border. The light falls on a white screen behind the slits. Instead of an image of two narrow slits, we find projected on the screen a panorama of the colors of the rainbow.

Consider two photons of exactly the same frequency that are in synchronization. That is the way they commonly come from a single point source. As the photons pass through their respective slits, they can go straight ahead or slightly to the left or slightly to the right. If they chance to meet on the left, for instance, they may or may not agree in phase when they hit the white screen. If they both have the same orientation of their neg-pos when they meet on the screen, a spot of their color will be visible. What is special about that spot is that the distance that one of the two photons traveled from its slit to the screen is exactly one wavelength longer than the distance that the other photon traveled. A wavelength is the distance between one neg-pos pair and the next neg-pos pair that has the same orientation. Since neg-pos pairs alternate between two orientations, the distance between any two neg-pos pairs is half a wavelength.

Light should travel in straight lines. It does so unless it interacts with something along the way. In this case the interference came from the molecules of the material that lines the borders of the slits. Some photons pass through the slits straight, some slightly shifted, some more shifted.

Now consider what happens to the photon that meets another photon when their orientations are opposite. Both photons disappear. They are neither absorbed nor reflected nor emitted. The neg of one attracts the pos of the other. Instead of groups of two, they become groups of four bits, all along their length. They have been converted into new entities that fly at the speed of light and never interact with anything, because they are electrically neutral. They are called neutrinos.

Neutrinos are mysterious and scary. When you have a kind of matter that other kinds of matter can turn into, and the matter that it turns into cannot become anything else, in the long run everything in the universe will turn into that kind of matter.

I know that is not happening, because the universe has been here long enough to have experienced everything that can happen. Furthermore, neutrinos are misunderstood.

Astrophysicists have reason to believe that there is invisible and undetectable matter throughout space. It seems that there is gravitational force that can't be accounted for in any other way.

The saddest part of the story is that gravity is not understood. I have a neat solution for that problem. Since everything, including neutrinos, consists exclusively of neg-pos bits, gravity is due to neg-pos. There is a force of attraction between neg bits and pos bits, and a force of repulsion between neg bits and other neg bits, and a repulsive force between pos bits and pos bits. The attractive force is slightly stronger than the repulsive force. The difference in strength between the two forces is gravity. Although the forces of attraction and repulsion are very much stronger than the force of gravity, the former generally cancel each other, but there is nothing to cancel the force of gravity.

The conversion of everything into neutrinos is not an irreversible process. There are many huge fiery furnaces , called stars, that turn everything into nice fresh individual bits that get reprocessed. It is recycling that occurs without our assistance.

____________________________________________________________________________________

____________________________________________________________________________________

REFLECTION AND WATER

Why does the color of a surface change when the surface becomes wet?

It is for the same reason that the color of an element is different from the color of a compound that contains that element. In the case of water, the compound molecule contains hydrogen atoms and oxygen atoms. The position of each electron shifts when the atoms combine to form the water molecule. That causes the possible frequencies of oscillation of electrons to change. Thus the colors that are absorbed change.

The color that we should see in pure water is blue, but the blue light that water scatters in all directions is pale. However, in lakes that are very deep, and the water is pure, the blue color is amazingly strong.

In the case of a wet surface (like a table top, for instance) the water does not combine to form molecules; but the effect is the same. The electrons in the water molecules have new points of zero net force, and therefore new frequencies of oscillation. This brings us to another viewpoint. The distinction between molecules of compounds that are formed in reactions between water and other molecules, and surfaces that are wet with water is academic. In both cases, the electrons in the water that are closest to the interface have a new point of zero net force, and therefore reflect different combinations of colors. We find a new general rule, that the internal structure of atoms changes with every change in the location of the atoms.

 previous page next page