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A question about the existance of a thread

  1. Sep 9, 2005 #1
    I know that my question is going to be misunderstood, but I am hoping that someone will read it for what it is and answer it directly:

    Is there a thread in this forum that discusses the idea that the speed of light may be slowing down. If yes, can you direct me to that thread?
  2. jcsd
  3. Sep 10, 2005 #2
    My understanding is that there are suggestions that the speed of light may have been different in the past. This is not necessarily evidence that the speed of light is changing today though, and it is possible that the speed of light when measured in the past would have been precisely the speed of light as we measure it today anyway, even if today we see "the speed of light in the past" as being different.

    (Basically that would be saying that no matter where or when you are, the speed of light is c.)
  4. Sep 10, 2005 #3
    It's easy to conceptualize a varying speed of light. What makes the idea unattractive to physicists is that you have to abandon a very high symmetry principle called "the principle of relativity."
  5. Sep 10, 2005 #4

    Try looking for Joao Magueijo and John Moffat and VSL theory. It's apparently not part of the lunatic fringe per se, but equally it is not widely accepted either (consider the use of the words "controversial" and "dubious" by mainstream physicists to describe it).

    Wikipedia has an article on it, but note that oddly enough one of the links at the bottom of that article is to "Creationists Interests". Is varying speed of light theory an attempt to reconcile the age of the universe to extremist Christian doctrine, is it being hijacked by such interests or had the author of the wikipedia article just noticed that creation scientists were taking an interest?

    I don't know the answer, but I suggest care when reading articles in this area.
  6. Sep 10, 2005 #5


    User Avatar

    Staff: Mentor

    None of you all answered the original poster's question directly! :biggrin:

    To the OP: Did you try the "Search" function listed in the navigation bar at the top of this page?
  7. Sep 10, 2005 #6
    I tried "speed light slowing" but I got too many hits and none of the ones I looked at seemed to be on the topic. Unfortunately for this search, there have been experiments in which the speed of light in various media are quite slow and this topic has been visited a lot on these threads.
  8. Sep 10, 2005 #7


    User Avatar

    Staff: Mentor

    Unfortunately, this site's search function doesn't seem to support searching on an exact phrase. However, Google does support exact-phrase searches, it indexes this site, and you can restrict searches to this site only. Try a Google search on the following:

    "variable speed of light" site:www.physicsforums.com

    The quotes tell Google that you want an exact match for that phrase. Also try some other similar phrases.
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