Light's Most Exotic Trick Yet: So Fast it Goes...Backwards?

[michaelmozina]

http://www.rochester.edu/news/show.php?id=2544<br /><br />Ok, now I'm very confused. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[tom_hobbes]

Wow. This reminds me of a short story by Bob Shaw.<br /><br />I don't know if anyone here ever read it, Light Of Other Days, from the fifties or sixties, it had an invention called Slowglass. This stuff could slow light to a crawl for the duration of it's passage through a pane, until years later the light exited the other side as a coherent view of whatever the glass was positioned in front of. Depending upon the thickness you could have a view of a tropical beach, or a Himalayan mountainside for months or years. It'd be cool if this research could lead to some sort of application...<br /> <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[TheShadow]

I’m not sure we can call these guys scientists. They are confusing the transmission of light with the propagating of the information about the light. As was demonstrated with experiments with Bose-Einstein Condensate, “light” does not actually “slow down”. <br /><br />When scientists “slowed light down” in a bose-einstein condensate of sodium vapor, they discovered something very interesting. According to these scientists, they didn’t actually slow the photons down. What happened is that when the photons entered the condensate, their patterns were transferred to the electron spins of the molecules of the vapor. At that point the photons themselves ceased to exits as photons. The vapor was brought to near absolute zero by using lasers to slow down the molecules until all motion was stopped. In this way they trapped the patterns of the photons in the stationary molecules. As soon as they allowed the molecules to “warm up” the patterns representing the photons continued their journey through the condensate to the other side. At that point, new photons were emitted which had the characteristics of the original photons, including frequency and direction. This also explains why light appears to “slow down” when “passing through” certain materials. Different materials transfer the patterns at a different rate.<br /><br />What this means is that the information which encodes the characteristics of the original light is propagated through the medium at a velocity that is determined by the physical characteristics of the medium, which is determined by the molecular motion of the molecules of the medium at the time. Note that the relative molecular motion can also be describe as the “temperature” of the molecules. <br /><br />Bottom line, if these guys think they have “slowed down”, “speeded up”, or “reversed” light, they simply don’t know what the hell they are talking about.<br /><br />BTW, why are you quoting that wingnut Birkeland on a post about light?<br /> <div class="Discussion_UserSignature"> <p> </p><p> </p><p> </p><p> </p><p><font size="1" color="#808080">Who knows what evil lurks in the hearts of men, the Shadow knows. </font></p> </div>

 

[nova_explored]

very nicely put Shadow. Thankyou.<br /><br />even watching the animation, it doesn't show the light (photonic wave) jumping ahead of itself. I don't get what the fuss is about.<br /><br />If it were truly in reverse we would see a change in the wavelength as the information from one end overtakes the other. <div class="Discussion_UserSignature"> </div>

 

[spacechump]

I blame the press and the fact that some scientists think that the only way to get into the headlines is to wow the public with misleading headlines and quotes.

 

[tom_hobbes]

Ahhh. Thanks for putting us straight. <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[siarad]

Yes they're confusing photons as the means of transmission of information.<br />This is akin to electrons moving slowly through a medium but the information travelling much faster.<br />Even more 'electricity' is reflected back from an open ended cable as is used in your PC PCI bus to voltage double as this light information seems to do.<br />Maxwell considered electricity to travel in space surrounding wires being guided by them.<br />Perhaps 'photonic information' does likewise & it's speed governed by space as with electricity.<br />The 'mirror TV' explanation doesn't ring true as different rays of light are being viewed not sped-up slowed-down ones <img src="/images/icons/rolleyes.gif" />

 

[nova_explored]

so another words, space is the primer for the passage of information, not the photon?<br /><br />"Maxwell considered electricity to travel in space surrounding wires being guided by them."<br /><br />i'm having trouble following that. <div class="Discussion_UserSignature"> </div>

 

[tom_hobbes]

I realised the mirror analogy was bollocks but I chalked that down to journalistic ignorance. Oh well. <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[michaelmozina]

<blockquote><font class="small">In reply to:</font><hr /><p>They are confusing the transmission of light with the propagating of the information about the light. As was demonstrated with experiments with Bose-Einstein Condensate, “light” does not actually “slow down”.<p><hr /></p></p></blockquote><br /><br />I think you explained the specific issues and confusion pretty elegantly. Thanks. <img src="/images/icons/smile.gif" /><br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>BTW, why are you quoting that wingnut Birkeland on a post about light? <p><hr /></p></p></blockquote><br /><br />Are you familiar with Birkeland currents? <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

 

[siarad]

Wasn't aimed at you just have to reply to someone here <img src="/images/icons/wink.gif" />

 

[tom_hobbes]

In any case, yar a bastid! <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[exoscientist]

This is analogous to experiments repeated by several researchers over the last few years.<br /> They appeared to show light travelling than c. <br /> The explanation offered is that the light pulses are shaped so that the front portion arrives earlier than main portion and this allows the full light pulse to be reconstructed before the main pulse arrives. <br /> This can give the impression that the light is moving faster than light or even that the pulse arrives at its destination before the main pulse leaves the origin point.<br /><br /> Some refs:<br /><br />Physics News Update Number 495 - Story SUPERLUMINAL LIGHT PROPAGATION.<br />http://www.aip.org/pnu/2000/split/pnu495-2.htm<br /><br />Scientists Claim To Break Speed-of-Light Barrier <br />By Maia Weinstock<br />Staff Writer<br />posted: 06:06 pm ET<br />19 July 2000<br />http://www.space.com/scienceastronomy/generalscience/faster_than_c_000719.html<br /><br />Wednesday, 19 July, 2000, 18:09 GMT 19:09 UK <br />Beam smashes light barrier.<br />"Dramatic demonstration <br />But the NEC scientists believe their work does not violate Einstein's theory. <br />"Writing in the journal Nature, Dr Lijun Wang and colleagues say their light beam raced through the atom trap so quickly that the leading edge of the pulse's peak actually exited before it had entered."<br />http://news.bbc.co.uk/1/hi/sci/tech/841690.stm<br /><br />May 30, 2000 <br />Light Exceeds Its Own Speed Limit, or Does It? <br />By JAMES GLANZ <br />"As most physicists interpret the experiment, it is a low-intensity <br />precursor (sometimes called a tail, even when it comes first) of the <br />incoming wave that clues the cesium chamber to the imminent arrival of <br />a pulse. In a process whose details are poorly understood, <div class="Discussion_UserSignature"> </div>

 

[kyle_baron]

It looks to me, that he's got an interesting toy. It'll probably end up in David Copperfields hands someday! <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>