Posted: Jun 12, 2018 11:32 am
PensivePenny wrote:DavidMcC wrote:Not THAT crazy, Macdoc, because the narrator is playing slightly fast and loose with words when he describes the photons as "bonded, like molecules". I suspect that the reality is that this is not a property of the photons, but more of their interaction with the rubidium atoms of the medium. Strange thing can certainly happen in such media, such as the group velocity of the light slowing almost to a halt (eg, bicycle speed).
EDIT: References from here:
https://physics.aps.org/story/v3/st37
Wow! I had no idea. Thanks for that link. Quantum mechanics is WAY beyond me, but I'm curious, does this have any impact on our understanding of the speed of light at the upper end? Since the majority of the univerese's known mass is unaccounted for, call it dark matter/energy or whatever, are there any implications of the rubidium experiment that might pertain to dark matter acting as a governor of light?
Penny, the "upper end" is c, the speed of light in vacuo.
The issue of dark matter is complicated, because there is more than one form of it. There is the "mundane" issue of dark bodies known as planets, which generally only reflect light (although gas giants may emit a limited amount of long-wavelength light, without having ignited as stars in their own right). Then there is the stranger phenomenon from deep space of apparent gravitational anomalies, capable of bending light from distant stars, and possibly accounting for the shortfall of mass in the known universe:
https://en.wikipedia.org/wiki/Dark_matter
...
The primary evidence for dark matter is that calculations show that many galaxies would fly apart instead of rotating, or would not have formed or move as they do, if they did not contain a large amount of unseen matter.[2] Other lines of evidence include observations in gravitational lensing,[3] from the cosmic microwave background, from astronomical observations of the observable universe's current structure, from the formation and evolution of galaxies, from mass location during galactic collisions,[4] and from the motion of galaxies within galaxy clusters.
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