May 15, 2012
Kate Pope Hodel, KCSourceLink
Glass Fiber - the material science of how it behaves
This post comes courtesy of John Pavlish, Global Scholar at the Kauffman Foundation. A graduate of MIT, he did his senior thesis in the Department of Material Science and Engineering. You can also read more at John's blog.
Google Fiber will be using a glass fiber connection. It will be the fastest connection of being able to transfer information. Here’s the science behind why it’s fast.
Copper wire conductivity
Nearly all electrical devices are connected with some metal wire, commonly a copper wire. The majority of the energy is transferred along a wire mostly with electromagnetism. Electromagnetism is the source of energy for how all electrical devices operate. The reason that most devices use a metal wire is that metal elements have the largest amount of electrons in a valence shell. A valence shell is a collection of the electrons at the very far edge of an atom, away from the core of protons and electrons.
The reason why valence shells are used for transferring energy is that these electrons are at a state that takes very little energy to transfer them between atoms. Thus, a collection of metal atoms in a long wire can easily transfer these electrons. When a photon, which is a single beam of light, hits one of these valence electrons, it excites the electron enough to have it jump to another valence shell within a different atom.
Since metal atoms are much easier at sharing their valence shells between each other, it is much easier for a single electron to move between atoms along a wire. It is possible for a single electron to travel several miles this way.
Glass fiber more interesting
What makes a glass fiber more interesting than a copper wire is that you do not need to transfer the photons between particles but directly transfer the energy of light. The analogy for a metal wire is the ability of opening a door to move to the next room, where each room is a metal atom. A glass room does not have any doors, just windows so that you can see between each room from one end to the other.
Glass is a state of matter between liquid and solid material. Most common examples of glass are used with silicon SiO2 molecules, seen as grains of sand on a beach. However, you can use any type of matter for a glass as long as you freeze the liquid while the molecules are still in separated blobs. This state is known as an amorphous material.
Fiber is just a construction of the molecules. Common examples of everyday fibers are cotton fibers woven for a shirt to the fibers of a piece of fruit. A glass fiber wire is a strand of amorphous glass. Since the glass is amorphous, there are never any sharp edges of molecules at rest. These edges or facets are what splits light apart, like a diamond gem which splits light into separate colors of light. It is great for beauty, but not practical for maintaining the original energy. In comparison, an amorphous glass state maintains the original fidelity of the light from its original source of energy because the molecules are split apart like a quasi-liquid state. By splitting the molecules beforehand, you can maintain the light energy.
Since a glass fiber directly uses light for transfer energy, you are using one of the fastest means of transferring energy. Light is the fastest known means of traveling, the speed being “c” or approximately 3*10^6 m/s or 6.7*10^6 miles per hour.
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