Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What do you make of this?

  1. Sep 11, 2007 #1
    I just stumbled upon this and I was wondering of it's validity.I would have thought if this was true it would have been out in the mainstream even more. It's from 2004 but i would think still relevant. I would like to hear some more about this from u guys...like, is this for real?....this seems to be one of those changes in physics that would screw up some stuff, no? What would the repercussions be if it happened again.

  2. jcsd
  3. Sep 11, 2007 #2


    User Avatar

    these Variable Speed of Light (VSL) theories spring up periodically. then they get some attention in the popular press. then they get refuted by the likes of Michael Duff
    http://www.arxiv.org/abs/hep-th/0208093 and http://xxx.lanl.gov/abs/physics/0110060
    or John Barrow
    point out what the problem is.

    i guess what i think i've said before:

    the laws of physics doesn't give a rat's ass about what units we use to measure things. the speed of light is necessarily always 1 Planck length per Planck time and if we think that the speed of light (in units we like to use) has changed, the more salient observation iis whether the number of Planck lengths per meter has changed or if the number of Planck times per second has changed, or both (these ratios are dimensionless numbers) and, if that is the case (making us think the speed of E&M propagation has changed, we should be noting the change in one of these dimensionless values and ask why that.
  4. Sep 12, 2007 #3
    Ok Thanks...I was just wondering. Because like you mentioned every once and a while you hear about it but i never asked until now.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook