• Question: Why is the speed of light constant?

    Asked by millerbei to Asif, Laura, Lena, Sean on 22 Mar 2012. This question was also asked by monkeyboii.
    • Photo: Sean Murphy

      Sean Murphy answered on 22 Mar 2012:

      The speed of light changes when traveling through different media. The speed of light in a vacuum is 299,792,458 m/s but light is slowed down in transparent media such as air, water and glass. We say the speed of light in a vacuum is constant due to ‘special relativity’, which states that:
      1. The speed of light is independent of the motion of the observer.
      2. The speed of light does not vary with time or place.

      This is a good explanation of special relativity if you are interested
      http://www.squidoo.com/relativity_explanation

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