GeeKay Posted January 23, 2015 Share Posted January 23, 2015 I've just read an article on the BBC website (see link below) in which experimentalists have reduced the speed of light by remodelling photons. Does this mean that the frequency of light is also reduced? http://www.bbc.co.uk/news/uk-scotland-glasgow-west-30944584 Link to comment Share on other sites More sharing options...
EdEarl Posted January 23, 2015 Share Posted January 23, 2015 If this experiment can be verified by an independent scientist or group, then current theories may be modified. IMO a slower photon would affect wavelength, but not necessarily frequency, but others are more qualified than I am to answer your question. Link to comment Share on other sites More sharing options...
Strange Posted January 23, 2015 Share Posted January 23, 2015 That BBC report is largely incomprehensible! The paper is here: http://www.sciencemag.org/content/early/2015/01/21/science.aaa3035(for those who have access) I haven't been able to find a better summary. Link to comment Share on other sites More sharing options...
Klaynos Posted January 23, 2015 Share Posted January 23, 2015 Sorry, brief reply limited on time. Read the abstract. It's taking about group velocity. They normally means (in previous reports of this nature) information transfer is still limited to c. Link to comment Share on other sites More sharing options...
swansont Posted January 23, 2015 Share Posted January 23, 2015 It's also a geometric effect: when you have a non-plane wave, you get a beam spreading out. The distance a photon travels is not the straight line from source to target center, but also includes a transverse displacement (a non-plane-wave beam spreads out). It looks like that accounts for the additional distance, and thus the delay. http://arxiv.org/pdf/1411.3987v1.pdf "The analytical form of this predicted delay (Eq. 1) suggests a simple geometrical model, where the delay arises from the additional length of the diagonal ray, propagating at an angle with respect to the optical axis. In Fig. 3B we compare the measured and predicted values for the delay, showing that Eq. 1 is valid over the range of Bessel angles that we tested. " 1 Link to comment Share on other sites More sharing options...
MomentTheory Posted January 24, 2015 Share Posted January 24, 2015 [see "Notes Chapter 2." The Elegant Universe. Boston: NOVA, 2003. 390-91. Print.] “When light travels through a substance such as air or glass its speed is decreased in roughly the same way that a rock dropped from a cliff is dragged to a slower speed when it enters a body of water." Link to comment Share on other sites More sharing options...
Robittybob1 Posted January 24, 2015 Share Posted January 24, 2015 [see "Notes Chapter 2." The Elegant Universe. Boston: NOVA, 2003. 390-91. Print.] “When light travels through a substance such as air or glass its speed is decreased in roughly the same way that a rock dropped from a cliff is dragged to a slower speed when it enters a body of water." But when it re-exits they say it regains its original speed. Did it have a higher frequency while in the denser medium? Link to comment Share on other sites More sharing options...
StringJunky Posted January 24, 2015 Share Posted January 24, 2015 But when it re-exits they say it regains its original speed. Did it have a higher frequency while in the denser medium? No, I don't think so. The apparent lower speed is caused by the photon interacting with the outer electron of each atom it encounters as it passes through the medium, resulting in an accumulated delay. It's speed passing between each atom is always c. Link to comment Share on other sites More sharing options...
swansont Posted January 24, 2015 Share Posted January 24, 2015 This experiment has nothing to do with passing through a medium. "Photons that travel in free space slower than the speed of light" Link to comment Share on other sites More sharing options...
Mordred Posted January 24, 2015 Share Posted January 24, 2015 https://briankoberlein.com/2015/01/24/need-speed/ Came across this good coverage, on my Google+ Thought I'd share it 1 Link to comment Share on other sites More sharing options...
Strange Posted January 24, 2015 Share Posted January 24, 2015 https://briankoberlein.com/2015/01/24/need-speed/ Came across this good coverage, on my Google+ Thought I'd share it That's a really good write up (IMHO ) Link to comment Share on other sites More sharing options...
MomentTheory Posted January 28, 2015 Share Posted January 28, 2015 This experiment has nothing to do with passing through a medium. "Photons that travel in free space slower than the speed of light" "They sent photons - individual particles of light - through a special mask. It changed the photons' shape - and slowed them to less than light speed." "Special mask" sounds like a type of medium. Perhaps it is a mask made from magic? Link to comment Share on other sites More sharing options...
swansont Posted January 29, 2015 Share Posted January 29, 2015 "They sent photons - individual particles of light - through a special mask. It changed the photons' shape - and slowed them to less than light speed." "Special mask" sounds like a type of medium. Perhaps it is a mask made from magic?[/size] They were measuring the spedd after having passed through the mask. Link to comment Share on other sites More sharing options...
MomentTheory Posted January 29, 2015 Share Posted January 29, 2015 After further review of the PDF document, it seems to me, they were actually measuring a delay, not speed. I understand their assumption between speed and the delay, but how can we be certain the delay is caused by a lowered speed in free space? What this suggests to me is that light carries information, almost as though it had been "aware" of its prior passing through the medium. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now