Mozart Transmitted at 4.7c?
Engineers in aerospace are always interested in sending information faster - instantaneously, if possible. Think about the one hour 20 minutes delay in a command signal to the Cassini spacecraft around Saturn.
Now there are claims of using quantum tunneling to send signals over short distances at super-luminal (>c) speed. Gunter Nimtz and colleagues claimed to have transmitted Mozart's Symphony No.40 at 4.7 times the speed of light through a tunneling barrier. How's that possible?
Most scientists agree that some effects can propagate at faster than the speed of light, but that no useful information can be sent that way. Nimtz did the 'Mozart trick" and apparently claimed: "if that's not information, then I don't know what information is". The question is: can Nimtz prove that the information actually went over his link at faster than light? I do not think so.
It is one thing to send RF pulses and time the transmission delay per pulse. Such delays are not very well defined in this sort of experiment, because information needs the whole pulse, not just the leading edge. My view is that he did a test where some sort of effect could be measured to have propagated at faster than light and then pumped Mozart over the link and said "viola!". How did he know the music went over faster than light?
SL: Your Aerospace Watchdog
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A resonably good discussion of such issues
SL, and all:
If you do a search for <"faster than" light> on Science Blog you will find Light's Most Exotic Trick Yet: So Fast it Goes ... Backwards?. I especially like the article it's referencing, at the University of Rochester (the link at the bottom of the article). There you will find additional resources, like movies, that may shed additional light. (No pun intended. :-) )
Have fun. :-)
David
RE: A reasonably good discussion of such issues
Hi David, thanks for the link.
That "reasonably good discussion" is here: http://physicsweb.org/articles/world/13/9/3/1
I think it's very good!
SL: Your Aerospace Watchdog
RE: A reasonably good discussion of such issues
SL:
I'm not sure what you mean by "That 'reasonably good discussion'".
The reference you give is certainly a good one (though it predates what I was referencing by about six years, it's certainly quite relevant). It also has some good explanatory graphics.
The reference in what I provided takes one to http://www.rochester.edu/news/show.php?id=2544 (the University of Rochester link I recommended people follow at the end of the article I originally mentioned). Where one will find a number of additional graphics and movies that may help readers see how even "light so fast it moves backwards" still doesn't violate any "faster than light" restrictions.
Just clarification, just in case.
David
RE3: A reasonably good discussion of such issues
Hi David.
Firstly I assumed that you refer to the article from the Blog link as the "reasonably good discussion". Secondly I missed the link at the bottom of the Blog posting, because it simply says "University of Rochester". Subsequently I found the link that I gave in one of the replies in the Blog...
Anyway, both are very good articles and are recommended reading. Tx for the clarification.
SL: Your Aerospace Watchdog
Re4: A reasonably good discussion of such issues
SL:
I figured it might be something like that (especially once I looked through the comment posts near the end and found the link you referenced).
Incidentally, the reason I referred to the post I linked (originally) as the "reasonably good discussion" is due to it being a word-for-word quote of the "University of Rochester" article it references. Unfortunately, though, it lacked the additional resources of the original (hence my suggestion to follow through to the original).
I suppose I should have simply referenced the original, but I thought it might also be helpful to let readers know that such resources are right here (on Science Blog) and just a simple search away.
Oh well...
David
Re5: A reasonably good discussion of such issues
While you two were at it, I noticed that the "similar entries" at top left also reference the Blog article. Another resource not to be forgotten...
Burt Jordaan (www.Relativity-4-Engineers.com)
Re6: A reasonably good discussion of such issues
Burt:
I didn't think we were "at it", at least not in any unfriendly way. :-)
I certainly hope SL hadn't taken it that way, or anyone else, for that matter. If so, I'm very sorry.
Yes, I hadn't looked at the "similar entries" portion of the page. However, I have to wonder whether these particular similar entries were there before we referenced them.
Unfortunately, unless someone noticed them beforehand, we may never know. :-}
David
Re7: A reasonably good discussion of such issues
Hi, David.
I noticed the similar entries list beforehand. It's a nice feature of Science Blog, although computer recognition of "similar" can sometimes produce weird results.
BTW, I think Burt's use of "at it" did not refer to an unfriendly interaction but simply in the sense of "while you're at it, could you pick up a quart of milk."
In other words, I read it as "otherwise engaged" not "in each other's face."
Fred Bortz -- Science and technology books for young readers (www.fredbortz.com) and Science book reviews (www.scienceshelf.com)
Re8: A reasonably good discussion of such issues
Fred:
So, are you saying that you noticed that one or both of the references SL and I posted were within the "similar entries" list before we posted our references? That would be great and remarkable. (Just as you say, a computer's "idea" of similar can leave much to be desired.)
By the way, I'm glad you interpreted Burt's comment as you did.
David
Re9: A reasonably good discussion of such issues
Hi David.
I actually noticed this particular "similar entry" ever since SL posted this Blog entry, but did not pay much attention, since it was "oldish" and I've read it before. So the 'computer recognition' worked just fine here.
BTW, I did intend my "at it" remark the way Fred interpreted it. I understood that there was just a bit of miscommunication, with no confrontational issues. :-)
Regards,
Burt Jordaan (www.Relativity-4-Engineers.com)
hmm.. .what?
I guess this is a Blog, stimulating discussion, not a technical article site.
Re: hmm... what?
I agree with the second Anonymous. SL tends to set a scenario and then ask a probing question. I love that on Blogs!
What is missing in the opening post is perhaps a link to some technical articles on this subject.
Burt Jordaan (www.Relativity-4-Engineers.com)
hmm
That's a shockingly sophisticated analysis of this research. I don't think my life could go on had I not read it.
Re: Mozart Transmitted at 4.7c?
Yea, it is hard to figure out how Nimtz determined that his piece of Mozart actually was transmitted at a propagation speed exceeding c. My money is on that his 4.7c was merely a measurement error (or trick?) using some form of radio wave (I believe it was microwaves in a waveguide). In order to know that you have exceeded the speed of light in a transmission, one must probably time single photons, not so? Otherwise, you may be timing some artifact of the apparatus.
Burt Jordaan (www.Relativity-4-Engineers.com)
exactly...
how do you measure faster-than-light speeds?
measure faster-than-ligh
You can compare a signal sent at the speed of light (usual way) with the test signal (superluminal) and see if there is a lag between them
Re: Mozart Transmitted at 4.7c? (exactly...)
"how do you measure faster-than-light speeds?"
Light moves about 1 foot in one nano-second (ns). So if you have an accurate enough timing device and you find that some signal took 0.8 ns to move the one foot between a transmitter and a receiver, you can conclude the the signal moved at roughly 1.25 times the speed of light.
Regards,
Burt Jordaan (www.Relativity-4-Engineers.com)
The devil is in the details...
Proving the transmission is easy!
All he has to do is decode the signal and the "far end" and play the audio...
Re: The devil is in the details...
Anonymous wrote: "All he has to do is decode the signal and the "far end" and play the audio..."
And how does he know that music signal traveled faster then light?
SL: Your Aerospace Watchdog
A previous commenter noted
A previous commenter noted the possible error of only tracking wave fronts, rather than the entire wave. If the 4.7c assertion is due to only tracking the wave fronts, I'm willing to bet that the signal can't be decoded after transmission.
In any case, decoding the signal is critical to any assertion that information can be passed faster than light. If the information can't be understood, what good is it?
(Yes, I'm distinguishing between information as defined in physics, and information as defined by engineers...)
Re: A previous commenter noted
" the possible error of only tracking wave fronts, rather than the entire wave."
I agree (obviously!)
SL: Your Aerospace Watchdog
wella?
perhaps you mean "voila" ?
Re: wella? (perhaps you mean "voila" ?)
Tx, fixed in OP...
SL: Your Aerospace Watchdog