OK, total stab in the dark re: the SLAC - and this is just based on your hint, and the articles use of "give-aways" such as:
"Physicists have long known....never observed directly" and, "first direct observation...long-predicted phenomenon."
These things throw up the same type of flags as "possibly," "could," "large," etcetera..
Anywho, this reads like the grand "something (matter) from nothing (energy)" and I automatically think: "BIG BANG!" (bleat?)"
I was thinking more along the lines of still trying to prove that Quantum Electrodynamics (QED) is correct, though we require it to be correct in order to make our calculations work. Those calculations are then used to provide evidence that QED works... That's circular logic at its best. Don't get me wrong though, I agree that QED (and QCD for that matter) are close approximations - I just seriously doubt that they are the final word on the subject. Any more correct than Newtonian gravity as compared to General Relativity, although, there is the potential that Newton may have been more correct, but there is another variable involved that GR accomodates and Newton never considered. It's a topsy-turvy world out there and scientists are often a bit too quick to yell Eureka!
1. When they say "From a standing start, the reconstructed beam sped back up to the normal speed of light. Analysis showed that it possessed exactly the same shape and wavelength of the original beam, although it was slightly weaker." What is meant by "weaker?"
Amplitude. It's signal strength was effectively lower than its original or that presupposed by summing the strength of the frozen wave with the energy input of the lasers.
I read on wiki that "frequency is an invariant quantity in the universe. That is, it cannot be changed by any linearly physical process unlike velocity of propagation or wavelength." So, "frequency" could not have changed, either... what did?
First, through a process of elimination, you did find the answer - AMPLITUDE. This is the signal strength (for lack of a better description). It is the measurement of peak to peak waveform "potential". As for the "invariant quantity" issue - don't worry about it... It's a matter of someone at Wiki being dramatic, although correct. Basically they are trying to say that, "what goes in must come out", although it may come out altered. Wavelength and velocity, the two terms that makeup frequency will invariably change as they are moving through a different medium, but it is the ratio between them that remains the same - thus f remains the same.
2. Is the "reconstructed beam" the same photons as in the original beam? Is there any way to know? (i.e., seems to me if it is "reconstructed" by shining the laser on the second set of sodium, then they must entertain the possibility that this is in fact a new "original" beam (from exciting the sodium atoms - even though they believe they have revived the "original")). And, now that I think about it (damn you, Merl!), if the "reconstructed beam" isn't exact (it's "weaker") then it's not much of a reconstruction, is it?
Now you are starting to see my point... This article was offered "as is" - meaning that the authors expected you to buy it hook, line & sinker without protest (much like most non-peer-reviewed articles are). It's a puff piece and they played fast & loose with the terminology. It reminds me of reading a science textbook in any school in the country.
No - it isn't the "exact same" as the original. Keep in mind, photons are considered to be 'fundamental' - meaning that they are constructed of nothing smaller. The only way to set them loose is to free them from something else. They are a packet of quanta and their velocity is directly proportionate to the energy required to set them free. Once they are stopped (absorbed), they can be 're-emitted' (same photon is possible but not a certainty) through excitation. If that excitation is not identical to the original excitation process - they will remain differentiated. So, the weaker beam indicates that there are losses in the system that they cannot account for and have no intention of explaining to you.
Like I said, interesting, but if this is their idea of "reconstruction," I'm not stepping into their transporter!
I'll be right there, standing next to you - NOT IN LINE FOR THE TRANSPORTER (yet), watching the lemmings running off the cliff (cheering them on).
Well, on subjects that you're passionate and knowledgeable about, it is going to be hard for you to post almost anywhere (except w/in your circles) without going too deep, too far, too fast. For example, I wiki'd "wavelength" and "frequency" to prepare my question above, and have to admit, looking at 'wavelength' graphically, I don't see how it's different from frequency (except by the equations).
And, I'll just give you my logic, so you can better gauge the depth, breadth, and speed of you responses (at least to me - lol). In my world, time cancels out, "Period" is "Distance" and Wavelength is Frequency.
See if this helps. I did it up really quickly, but it should cover the basics:
If you're wondering, "yes," I passed my college physics course.
But, the thing with that (and all education) is that I just plugged numbers into equations to (hopefully) get a "right" answer. I never had the time / luxury of thinking about the equations and their implications.
Aye, that's a lot of the problem today... "Plugging in" instead of "turning on". I prefer to tune students in to the mystery and make 'em capable of solving it for themselves. Taking their calculators away helps too!
I have Master's researchers that throw complete hissy fits when I do that, but I'm a stickler for demonstrating that they "KNOW" how to do the work. They thank me................ eventually.
With all that, I understand the reason for f = P/T, l = V/f (to account for apparent changes when waves change mediums). But, and along the lines like our discussion on the prior page re: gravity, I think these equations are are just human constructs - not physical Laws. Kind of circular, too. I'll maintain that Wavelength IS Frequency, the problem is Speed: our concept of distance, or time, or both distance and time.
Ouch... Hopefully this view changes after reading the "cheat sheet" above. We can discuss the rest when you respond.
Well, that ought to occupy a few minutes of "time" while you beat your head against the desk in frustration. Glad to help.
Nicely done - but I'm dent free. Those were good questions.
I don't recommend a bank job for you, then.
That's funny! I didn't even consider that reply when I typed the original comment. Good work Daffy. Anyway, I had to keep it short today, I have a date with the girls to watch Aragon in a few minutes.
