I don't know if this belongs in the Relativity forum or the Quantum Physics forum. Mentors, please move this if it is in the wrong forum. Recently, I have read several posts on physicsforums claiming that photons always travel at c. The reason light (not photon) travels slower than c in media other than a vacuum is that the photons are absorbed and reemitted by atoms in the medium. I looked around on the wider web and found that this view is widespread. Yet there are several problems with it. 1. How do all the atoms in the medium conspire to delay the same amount of time from absorption to reemission? 2. How do the all the photons conspire so that each gets absorbed and reemitted the same number of times? 3. How do the atoms conspire to maintain the phase coherence of laser light? 4. How does the absorbing atom remember the direction that the photon was travelling before it was absorbed? In addition, I have this question. In experimentally observed instances of absorption and reemission of photons, are the time delays compatible with this view? My guess (not scientific) is that the delay times are way too long to support this view of light in media. Does someone have data? If the experimental delay times are too long, then in my opinion people are describing two different kinds of absorption-reemission mechanism. One of these has experimental evidence and the other does not. This speculative mechanism is then being applied in a rather classical way to a situation where quantum mechanics should prevail. In that regime, the more sensible the picture you draw, the more likely it is wrong. And yet, the view is widespread. Am I the only person here who has problems with it?