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Author Topic: Breaking the light speed barrier- done!  (Read 9113 times)

Offline qpan

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Breaking the light speed barrier- done!
« on: 09/12/2003 01:35:34 »
WoW! i was browsing the internet when i found a couple of articles about the breaking of the light speed barrier. And they appear to be quite genuine! (found on CNN website). Anyone know much more about this? Seems very interesting. It also seems very strange- apparently the experiment diddn't just break the light speed barrier, it completely shattered it!

http://www.cnn.com/2000/TECH/space/07/20/speed.of.light.ap/
or a slightly longer version here:
http://www.cnn.com/2000/fyi/news/08/21/speed.of.light/

and from a different source:
http://www.howstuffworks.com/news-item6.htm

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« Last Edit: 09/12/2003 01:39:21 by qpan »


 

Offline Ylide

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Re: Breaking the light speed barrier- done!
« Reply #1 on: 09/12/2003 03:57:14 »
...

I'm speechless.  

This seems to be a special case, though, so relativity may still hold true.  (Kind of like how brownian motion is a small scale violation of thermodynamics yet the theory holds true)

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Offline qpan

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Re: Breaking the light speed barrier- done!
« Reply #2 on: 09/12/2003 13:10:24 »
Yes- this does seem to be a very "mind boggling" special case- i thought that photons always travelled at the speed of light- doesn't this violate that fact?

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Offline chris

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Re: Breaking the light speed barrier- done!
« Reply #3 on: 09/12/2003 17:24:15 »
Very interesting. But I am concerned that I have not heard any more about this since. That's usually a bad sign.

But it does remind me of a more recent experiment in which scientists slowed light down - anyone got the reference ?

Chris



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Offline Ylide

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Re: Breaking the light speed barrier- done!
« Reply #4 on: 10/12/2003 05:22:15 »
Something bothered me about that 2nd article though....they were claiming to have observed the light exiting the chamber before it ever entered.

That sort of thing boggles my mind.  Aside from the fact that I didn't think we had instrumentation sensitive enough to measure anything moving that fast (310*186,000 m/s) how the hell does that work?  Is space time warping to prevent the speed of light from being exceeded?  What's happening here?





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Offline qpan

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Re: Breaking the light speed barrier- done!
« Reply #5 on: 10/12/2003 14:40:10 »
Yeah- that bit does seem a bit strange, but i think that it says the exiting beam only leaves after the leading edge enters:
"But Chadi said that, despite published reports to the contrary, the high velocity does not cause the light to exit the chamber before it enters it. That would defy the fundamental theory of causality, that one thing causes another."
"A pulse generated from the leading edge of the light pulse does leaves the chamber before the peak of the light enters it. This relates to the fact that the pulse, although it may look like a straight beam, actually behaves like waves of individual light particles."
Very strange, but not so strange that the other beam leaves before the main beam enters, which would imply that the exiting beam "knew" it had to set off before the main beam was fired, which would in turn mean that there is no such thing as causality and that the future is completely preprogrammed- which i sincerely hope it is not!

"I have great faith in fools; self-confidence my friends call it."
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« Last Edit: 10/12/2003 14:54:42 by qpan »
 

Offline qpan

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Re: Breaking the light speed barrier- done!
« Reply #6 on: 10/12/2003 14:56:25 »
Also, what happens to the light? If it is travelling faster than light speed, surely it will go back in time, or is Einstein's theory wrong?

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Offline Ylide

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Re: Breaking the light speed barrier- done!
« Reply #7 on: 10/12/2003 19:25:23 »
If it's exiting the testing chamber before it enters, that sounds like going back in time to me.



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Offline chris

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Re: Breaking the light speed barrier- done!
« Reply #8 on: 10/12/2003 21:03:21 »
Sorry if I've got the wrong end of the stick, but one of the references to the story that you gave above actually says that "the wave front leaves the chamber before the rest of the wave has left".

This is not the same as the wave leaving before it has entered !

Chris

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Offline Ylide

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Re: Breaking the light speed barrier- done!
« Reply #9 on: 11/12/2003 03:03:01 »
Maybe I misunderstood....it's finals week.  

And I'm now finished with exams and have 6 blissful weeks off.

*breaks out a pint*



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Offline Quantumcat

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Re: Breaking the light speed barrier- done!
« Reply #10 on: 11/12/2003 11:14:41 »
Lucky you, we get ten days for christmas. In Austraia I got two months =(

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Offline chris

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Re: Breaking the light speed barrier- done!
« Reply #11 on: 11/12/2003 13:31:50 »
2 months Christmas holiday - presumably that's because the weather is nice at Christmas ?

I'm betting you get bugger all "summer" holiday (in July / August) when your weather is sh1t ?

Chris

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Offline tweener

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Re: Breaking the light speed barrier- done!
« Reply #12 on: 14/12/2003 01:04:14 »
Don't complain about 2 weeks off for Christmas.  Those of us with "real" jobs get one day (Dec. 25).  Enjoy your time off everyone!

Back to the speed of light article.  All they have done is shoot a laser through a medium where the speed of light is slightly faster than it is in "free space", that is a vacuum.  They stated very clearly and several times this is not inviolation of Einsten's relativity.  The "speed of light" is fixed for the medium in which the light is traveling and we usually refer to the speed of light in a vacuum.  The speed of light in water is slower, but fixed.  The speed of light in cesium vapor  in this experiment is faster than in a vacuum, but is still fixed.


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Offline Ylide

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Re: Breaking the light speed barrier- done!
« Reply #13 on: 14/12/2003 09:43:58 »
What do you mean by "fixed for the medium?"  I have not taken physics beyond electricity and magnetism but I was under the impression that the theory of relativity said that the only the speed of light is constant and everything else is relative to a system / observer?

And isn't 310 times the speed of light a wee bit more than "slightly" faster?  =)  



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Offline tweener

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Re: Breaking the light speed barrier- done!
« Reply #14 on: 14/12/2003 22:43:02 »
That's what I meant by "fixed".  It is constant for the medium in which it is traveling.

And, I would say that 310 is not a very large factor.

The original press release ( http://www.nec.co.jp/press/en/0007/1901.html ) states the following:

 
quote:
Scientists at NEC Corporation's (NEC) (NASDAQ: NIPNY) (FTSE: 6701q.l) basic research unit in the United States, NEC Research Institute (NEC-I), have proven light can travel faster than its acknowledged speed in vacuum*1 in a successful experiment in superluminal light propagation. Despite exceeding the vacuum speed of light, the experiment is not at odds with Einstein's theory of relativity and is explainable by existing physical theory. The research work, which may result in significantly faster information transfer speeds across networks and in computers, is to be published in the July 20th issue of Nature in a paper by NEC research scientists Dr. Lijun Wang, Dr. Alexander Kuzmich and Dr. Arthur Dogariu.


Salient points here are
1.  That light can travel faster than its speed in a vacuum.
2.  The experiment is not at odds with Einstein's relativity.
3.  The experiment is explainable by existing physical theory.


This is exciting work, but it is not faster than light travel.

I also read some of the other "news" articles, and they were very sad in their interpretation of the original artcle.  Sensationalism is not necessary in science reporting.  And, even worse, the BBC was one of the worst articles!  [V] They are usually one of the better news orgs.



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Offline Ylide

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Re: Breaking the light speed barrier- done!
« Reply #15 on: 15/12/2003 11:34:07 »
So 3x10^8 m/s is the speed of light in a vacuum...period.  It goes faster or slower in a different medium but remains constant in that medium.  Gotcha...all clear now.  All these guys did was develop a medium in which photons can travel faster than they could in a vacuum, then?



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Offline chris

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Re: Breaking the light speed barrier- done!
« Reply #16 on: 15/12/2003 23:12:12 »
Well I'm glad we cleared that one up !

Chris

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Offline tweener

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Re: Breaking the light speed barrier- done!
« Reply #17 on: 16/12/2003 23:20:25 »
Well, sort of.  What they did was develop a medium that allowed certain wavelengths to travel faster than others, with a really strange relationship.  It really is exciting work for the possibilities it raises in computing and transmission lines, but it's really not FTL travel of an energy pulse.


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Re: Breaking the light speed barrier- done!
« Reply #17 on: 16/12/2003 23:20:25 »

 

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