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Can light be slowed

  1. Nov 3, 2005 #1
    i read an article below and i wonder if it has any relevance in fundamental physics principle of constant sped of light


    IBM slows light, readies it for networking
    By Michael Kanellos, CNET News.com
    Published on ZDNet News: November 2, 2005, 10:39 AM PT

    Forward in EMAIL Format for PRINT ZDNet Tags: Processors Networking Energy Intl Business Machines Corp
    IBM has created a chip that can slow down light, the latest advance in an industrywide effort to develop computers that will use only a fraction of the energy of today's machines.

    The chip, called a photonic silicon waveguide, is a piece of silicon dotted with arrays of tiny holes. Scattered systematically by the holes, light shown on the chip slows down to 1/300th of its ordinary speed of 186,000 miles per second. In a computer system, slower light pulses could carry data rapidly, but in an orderly fashion. The light can be further slowed by applying an electric field to the waveguide.

    Researchers at Harvard University and the University of California, Berkeley, have slowed light in laboratories. IBM, though, claims that its light-slowing device is the first to be fashioned out of fairly standard materials, potentially paving the way toward commercial adoption.

    A number of companies and university researchers are currently tinkering with ways to replace the electronic components inside computers, which ferry signals with electrons, with optical technology. Optical equipment ferries data on photons, the smallest measure of light. Photons are far faster. More important, optical equipment generates less heat, curbing the growing problem of heat and power consumption.

    The catch, however, is that until recently, creating optical components has been more of an art than a science. The components cost a lot to make and can't be cranked out in the millions like silicon chips. Another factor: Optical parts are typically big, unlike silicon chips, which measure only a few millimeters on a side.

    Progress in blending the best of both technologies is advancing rapidly, however. Intel has demonstrated a Raman laser fashioned from silicon. Intel and start-up Luxtera have shown off silicon modulators, which chop up the light from a laser so that it can represent data.

    IBM's silicon waveguide, as the name suggests, would channel light pulses created by the laser and modulator.

    When the optical conversion might start to occur is a matter of speculation. Luxtera has said it will start to commercially produce products in 2007. The computer industry, however, tends to move slowly when it comes to major overhauls of computer architecture. Several components will have to be developed before photos can replace electrons inside computers.

    A paper providing details on the chip will run in Nature on Wednesday.
  2. jcsd
  3. Nov 3, 2005 #2


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    Again, this comes repeatedly. You need to understand what is meant by the "speed of light" in a medium, i.e. understand the difference between group velocity, phase velocity, and signal velocity. You also missed light being "slowed" down to ZERO m/s from a few years ago.

    This advice also applies to the "superluminal" pulse of the NEC experiment of a few years ago.

  4. Nov 4, 2005 #3


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    Cherenkov radiation is light emitted when a charged particle passes through an insulator at a speed greater than that of light in the medium. The characteristic "blue glow" of nuclear reactors is due to Cherenkov radiation.

    Here's some links for you to read if you are interested in understanding how it happens:
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