Beautiful physics: Tying knots in light

Oct 29, 2012
Beautiful physics: Tying knots in light

New research published today seeks to push the discovery that light can be tied in knots to the next level.

Dr Anton Desyatnikov from the Nonlinear Physics Centre at The Australian National University is part of an international team of scientists who are designing knots in light, with potential applications in advanced modern optics, laser beams and even quantum computing.

Using concepts from mathematics and physics the model Dr Desyatnikov and his colleagues have explored creates optical vortices with dark cores in a bright , that can then tangle and form links and knots.

"Apart from their curiosity value, what's really interesting and useful about these knots of darkness is that they show you what the power flow is doing," Dr Desyatnikov said.

"It is part of the incredible progress science is making in the field of optics, we're beginning to do things with light that would have once seemed impossible."

"The idea of a of light is something scientists have been exploring for years and a few groups have managed to achieve just that by precisely engineering laser beams with "artificial" or "hand-made" knots. But what we've been working on are models in which the knots spontaneously form on their own, just like those annoying knots that you always get in electrical cables.

"However unlike electrical cables which love to form knots, light doesn't. Scientists have found that inducing knots to form in laser beams by introducing perturbations in the form of laser speckle only very rarely induces knots.

"Our models suggest that you have to get the key parameters of the light in a certain range before you can easily tie the in knots but once you do, the knots are virtually guaranteed," he said.

"The really interesting thing is that we can't predict exactly where they will form. Just that under these specific circumstances the optical vortices will spontaneously nucleate and tie themselves into little knots."

Explore further: What is Nothing?

More information: www.nature.com/srep/2012/12102… /full/srep00771.html

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User comments : 14

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foolspoo
1 / 5 (2) Oct 29, 2012
Very interesting.
Anyone know of possible applications this can advance?
kochevnik
2.5 / 5 (8) Oct 29, 2012
Anyone know of possible applications this can advance?
Build atomic nuclei with trapped light. After all that's what matter is.
tadchem
3 / 5 (2) Oct 29, 2012
Next: an exploration of the physical properties of these vortices - mass? charge? angular momentum? inertia? Can they be manipulated?
EvgenijM
not rated yet Oct 29, 2012
Can electron and other elementary particles be a knoted em-wave that propagates in a loop?
vacuum-mechanics
1 / 5 (3) Oct 30, 2012
New research published today seeks to push the discovery that light can be tied in knots to the next level.


This seems great; unfortunately nowadays physicists still not clearly understand basic properties of light, i.e. what it is, how it was created and propagate, why it has no rest mass, etc. May be this unconventional physical view could help to understand the mechanism of light knots.
http://www.vacuum...20〈=en
johanfprins
1 / 5 (3) Oct 30, 2012
Can electron and other elementary particles be a knoted em-wave that propagates in a loop?
NO!

A free matterr-wave is only stationary within ONE of all possible inertial refrence frames (IRF's). Within all the other IRF's the same wave is SIMULTANEOUSLY not stationary.

It is easy to derive that a moving matter wave is a coherent electromagnetic wave which is modelled by Maxwell's equation for light-energy.

When you use the Lorentz-transformation to transform the lengths of these simultaneous waves into the IRF in which they are all a single stationary wave, you obtain a spherical EM-wave.

This means that within the IRF in which the matter-wave is stationary the EM-energy is confined by a spherical cavity with perfectly reflecting walls.

Propagating in a loop is not possible for such a wave just like a de Broglie wave cannot propagate along a circle around an atom's nucleus. This is why the old QM had to be replaced by Schrodinger's stationary waves.
johanfprins
1 / 5 (3) Oct 30, 2012
This seems great; unfortunately nowadays physicists still not clearly understand basic properties of light, i.e. what it is,


I disagree: Maxwell's equations models light perfectly.

how it was created and propagate,


This is well-known and can be modelled accurately by using Maxwell's equations.

why it has no rest mass,


This is also well-known from Einstein's STR: Free light moves with the same speed c relative to ALL inertial reference frames (IRF's). There is thus no IRF within which free-light can be stationary: Therefore it does not have rest-mass.

Rest-mass only manifests when an object has stationary inertia. Galileo already discovered this concept more than 400 years ago. And Newton subsequently quantified it in terms of "rest-mass" more than 300 years ago.

That the majority of theoretical physicists (tp's) cannot grasp the latter does not mean that it cannot be understood. It only means that the mainstream modern tp's are crackpots
MaxwellsDemon
4 / 5 (1) Oct 31, 2012
It only means that the mainstream modern tp's are crackpots.

Right. Because everyone knows that bona fide theorists only publish their work in Physorg comment threads… 0.o

"They all think I'm crazy, but I know better. It is not I who are crazy. It is I who am *mad*! Can't you hear them? Didn't you see the crowd?"
johanfprins
1.8 / 5 (4) Nov 01, 2012
It only means that the mainstream modern tp's are crackpots.

Right. Because everyone knows that bona fide theorists only publish their work in Physorg comment threads… 0.o

"They all think I'm crazy, but I know better. It is not I who are crazy. It is I who am *mad*! Can't you hear them? Didn't you see the crowd?"


You claim that what is improbable MUST be impossible: This is the best trademark of a real crackpot!

I can hear them provided they are willing to argue real physics; but as long as they believe that what you do at present changes the past, they are crackpots!

For as long as entropy increases or decreases, as it does at present in our universe, time has a direction since all processes develops irreversibly towards a final equilibrium state: Only then time becomes reversible.
Pkunk_
2 / 5 (3) Nov 04, 2012
@kochevnik said -
Anyone know of possible applications this can advance?
Build atomic nuclei with trapped light. After all that's what matter is.

While it would take a HUGE amount of energy , the really interesting thing could be then theoretical possibility to create anti-matter in equal amounts as matter. That stuff is worth at least the price of gold cubed .
ValeriaT
1 / 5 (2) Nov 04, 2012
The title picture is somehow similar to way, in which I do imagine the proton and neutron composed of quarks.
Torbjorn_Larsson_OM
not rated yet Nov 04, 2012
This is complementary to how you can twist the topology of the wavefront of light, as they test for high speed communication or high quality analysis.

@ foolspoo: Topologically stable systems are great for communication and/or computing, whether classical or quantum. Dunno if these are stable though.

@ kolchevnik, EvgenijM: No, not even close. The strong force fields build nuclei. Dynamic EM builds the chemistry of atoms. And we know that topological knots on their lonesome are not enough to build interesting quantum systems. Many have tried - not enough degrees of freedom for non-relativistic versions I think - and we would have relativistic problems as several notes.

@ vacuum-mechanics: Everyday physics is completely understood. That includes much of what you say is outstanding issues. Look it up!
Torbjorn_Larsson_OM
not rated yet Nov 04, 2012
@ johanfprins:

- "Rest mass" is inertial mass in relativity, sure. But to go from there back to pre-relativistic concepts of "stationary" absolute systems is not possible.

- There are many time arrows.

The entropical or quantum entanglement one of coarse grained systems is constrained by cosmological expansion, they need this universal sink that the cosmological arrow of time provides.

In inflation, which generically is eternal inflation, that cosmological arrow is emergent, ultimately provided by the existence of terminal vacua in the multiverse. (See Susskind, many 2012 papers on arxiv on that.)

- The persistent state of eternal inflation is a fractal flow, see for example Susskind's "Fractal-Flows and Time's Arrow", arxiv 2012. It isn't an equilibrium, and the overall system is irreversible on account of the terminal vacua.

It is very neat! A natural arrow of time, no problem with Boltzmann Brains, naturally a Standard Model sector of particles, et cetera.
mysoulwanders
not rated yet Nov 09, 2012
@foolspool
You can use this technique for a TRUE random number generator for both encryption purposes or more fun in random dice throws for gaming ;)