Does anyone know anything about John Singleton who thru 2006-2009 claims to have made radio waves travel faster than light?
(He does this by 'abusing' them!!!???)
Googling just gives me loads of articles which seem to be cut&paste from same source(s)
Is it some kind of April Fool that got out of hand??
Seems legit...
http://www.magnet.fsu.edu/search/personnel/getprofile.aspx?fname=John&lname=Singleton
Singleton, J.; Ardavan, A.; Ardavan, H.; Fopma, J.; Halliday, D. and Hayes, W., Experimental demonstration of emission from a superluminal polarization current- a new class of solid-state source for MHz-THz and beyond, IRMMW2004/THz2004, Karlsruhe, October (2004); Published in IEEE Conference digest 04EX857, 04EX857, 591-2 (2004)
Interesting! I found this article on Wikipedia, and apparently even thought under certain circumstances the "group velocity" of a wave can exceed the speed of light, this does not mean that any information travels superluminally:
http://en.wikipedia.org/wiki/Dispersion_(optics)#Group_and_phase_velocity
The article quotes the following Nature article, which I haven't read:
Stenner, M. D., Gauthier, D. J., and Neifeld, M. A. (2003). "The speed of information in a 'fast-light' optical medium". Nature 425: 695.
I'd reserve judgement until reading the actual article to see what kind of stipulations apply in these cases, but on the surface at least it appears legit.
Originally posted by PBE6Thats way beyond me!
Interesting! I found this article on Wikipedia, and apparently even thought under certain circumstances the "group velocity" of a wave can exceed the speed of light, this does not mean that any information travels superluminally:
http://en.wikipedia.org/wiki/Dispersion_(optics)#Group_and_phase_velocity
The article quotes the following Nature article, whi ...[text shortened]... kind of stipulations apply in these cases, but on the surface at least it appears legit.
I'll wait for a layman's explaination.
Thanks.
Originally posted by PBE6But then it's only the group velocity which is faster than light, not the signal velocity.
Interesting! I found this article on Wikipedia, and apparently even thought under certain circumstances the "group velocity" of a wave can exceed the speed of light, this does not mean that any information travels superluminally:
http://en.wikipedia.org/wiki/Dispersion_(optics)#Group_and_phase_velocity
The article quotes the following Nature article, whi ...[text shortened]... kind of stipulations apply in these cases, but on the surface at least it appears legit.
Originally posted by AThousandYoungWhat I know is from my own field and data filters, so I don't know if it is exact in this case. Anyway, since this is non-technical it might not matter...
Right. I remember something about this, but it sounds like you know more. Can you offer the layman's version?
In a wave, the peaks will seem to "increase" and "decrease" as the wave moves. Like the wiki illustration here:
http://upload.wikimedia.org/wikipedia/commons/b/bd/Wave_group.gif
You can then see that the wave seems to move faster than its shape, because the highest peak eventually starts "decreasing" and the next peak becomes the largest one. So eventually you'll reach the same shape as before, but with the previous peak being the highest one! The speed of that shape is the group velocity.
Signal velocity is the speed at which a wave carries information. Imagine a disturbance in the wave, that disturbance would move at a certain speed which is the signal velocity. The easiest way to think about it is how fast it gets from point A to B from the moment when you originally send it from A (sometimes also called the front velocity, but it's the same AFAIK).
Originally posted by PalynkaThanks for the link. cant get my head around it at the moment though! 😕
What I know is from my own field and data filters, so I don't know if it is exact in this case. Anyway, since this is non-technical it might not matter...
In a wave, the peaks will seem to "increase" and "decrease" as the wave moves. Like the wiki illustration here:
http://upload.wikimedia.org/wikipedia/commons/b/bd/Wave_group.gif
You can then see tha ...[text shortened]... lly send it from A (sometimes also called the front velocity, but it's the same AFAIK).
Originally posted by wolfgang59Imagine a long conga line of people. Every beat in the music, someone raises their hand in sequence; first the first guy, then the second on the second beat, then the third on the third beat...
Thanks for the link. cant get my head around it at the moment though! 😕
Every four beats everyone also takes a step forward.
The "raised hand" will move faster than the individual people will.
Or better, think of a football game when people do "the wave". "The wave" moves around the stadium very quickly but each person stays in their own spot.
Originally posted by AThousandYoungI went to a football match with my girlfriend once. And a wave started at the other end. The wave approached and I made my part of the wave. I was excited because this was my first crowd wave ever, so I turn to my girlfriend to tell her my impression. But she wasn't there, I couldn't see her. She had propagated with the wave.
Or better, think of a football game when people do "the wave". "The wave" moves around the stadium very quickly but each person stays in their own spot.
Later she came back with two hot dogs in her hand and gave me one of them. I asked her how it felt to be carried away by the wave, but she just said that it was nothing. She didn't really understand what I meant.
Fantastic, isn't it!?
Originally posted by AThousandYoungBut isnt that the speed of the wave? (ie c for radio waves)
Imagine a long conga line of people. Every beat in the music, someone raises their hand in sequence; first the first guy, then the second on the second beat, then the third on the third beat...
Every four beats everyone also takes a step forward.
The "raised hand" will move faster than the individual people will.
Or better, think of a football ...[text shortened]... "The wave" moves around the stadium very quickly but each person stays in their own spot.