Lowering the speed of light

[GeeKay]

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

[EdEarl]

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.

[Strange]

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.

[Klaynos]

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.

[swansont]

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. "

[MomentTheory]

[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."

[Robittybob1]

 

[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?

[StringJunky]

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.

[swansont]

This experiment has nothing to do with passing through a medium. "Photons that travel in free space slower than the speed of light"

[Mordred]

https://briankoberlein.com/2015/01/24/need-speed/

 

Came across this good coverage, on my Google+

 

Thought I'd share it

[Strange]

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 )

[MomentTheory]

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?

[swansont]

"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.

[MomentTheory]

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.