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Tying Knots With Light
thedreadedwiccan points out a summary of a recently released physics paper about tying knots with light. A pair of researchers showed that a relatively new solution to Maxwell's equations allows light to be twisted into stable loops. They are designing experiments to test the theory now, and it could have a big impact on fusion technology. The paper's abstract is available at Nature, though a subscription is required to see the rest. Quoting:
"In special situations, however, the loops might be stable, such as if light travels through plasma instead of through free space. One of the problems that has plagued experimental nuclear fusion reactors is that the plasma at the heart of them moves faster and faster and tends to escape. That motion can be controlled with magnetic fields, but current methods to generate those fields still don't do the job. If Irvine and Bouwmeester's discovery could be used to generate fields that would send the plasma in closed, non-expanding loops and help contain it, 'that would be extremely spectacular,' Bouwmeester says."
The real question is was a silver hammer necessary?
1. How do you bend light without passing it through matter or using a grav field that will crush the experiment?
2. If they can bend light, why are we using electron beams for crt's?
3. If you could build loops of light can they be modulated to store information and read it back again?
Yes, but plasma consists of charged particles which can be trapped by electro-magnetic fields. Light (in the wave picture at least) is simply an electro-magnetic field, so if you can tie light in loops theoretically you can also trap the plasma too. Now I agree that applications are a long way off - this is a theoretical paper so presumably no one has (intentionally) done it yet. If this proves interesting someone would have to build/modify an existing experiment to create and detect the phenomenon, and then there's a long way from there to a practical device, assuming it actually proves technically feasible.
Its been awhile since I've had anything with Vector Calculus, but doesn't a stable loop of light violate Maxwell's Equations in some way? Divergence of B = 0, Div of E = p/epsilon, Curl of E = dB/dt. Seems like a stable knot might not fit with that. Anyone more math savvy know?
If it is possible it probably appears in nature.
Well, they could zero the pagerank on sites that show different stuff to googlebot vs ordinary mortals.
Most journals make you transfer copyright to them. Making your paper available is then illegal.
It's changing, faster and faster. More journals are opening their archives after one or two years.
Of course, you can always go to a library and get a paper for free. Even the local library in the town of 800 people I grew up in had a borrowing agreement with more than one university library.
Most journals make you transfer copyright to them. Making your paper available is then illegal.
That's pure evil. Why do people keep submitting material to them? Journals that do that should lose their credibility.
It's changing, faster and faster.
I hope you are right.
How about this: if you received any (one penny or more) public grants or public funds to perform your research, then that research must be available to the public free of charge. If you are wealthy and want to entirely fund your own research (for example), then you may do whatever you like with the results. The part that I consider bullshit is the idea that tax dollars are taken from me by force or threat of force under a confiscatory tax system and then I am denied access to what this money is purchasing.
It is a miracle that curiosity survives formal education. - Einstein
I read the summary as more of a better feedback system. The earlier you can detect abnormalities, the earlier you can correct them. If the loops are only stable when the plasma is correctly configured, then your feedback becomes almost instantaneous from the time the plasma begins to destabilize, rather than being a rather slow interpretation of data from sensors that will only spot a problem once it passes the error threshold for that sensor. It would be like using the interference pattern from a tuning fork, rather than trying to copy the sound - the feedback loop becomes a part of the system.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)