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back to article Curved light drives boffin one-upmanship

For four years, scientists have been on an international race to exploit a property of a peculiar kind of light called an “Airy beam”. Now, not one, but two groups of researchers are laying claim to the prize. The beam, named after 19th century scientist Sir George Biddell Airy, was first observed in 2007. At the time, it was …

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Black Helicopters

Interesting timing...

Given the rather odd timing the first thought I had was that the Aussies got their first. But that thanks to the Echelon industrial espionage project the merikano's were just a packet sniff behind.

Especially given that Australia is amongst some of the more dimwitted countries that actually willingly facilitate / "participate" in this in the hope of a few intelligence crumbs tossed their way, too corrupt/dumb to realise they are helping the U.S. spy on their own citizens' innovations.

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Innovations

I thought the last innovation to come out of Australia was the rotary washing line.

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Ru

All that and more.

Have a read up on CSIRO. They've accomplished a fair bit.

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Coat

Re: All that and more.

Yes, it's not just blokes in bush gear talking about their "adventure".

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Coat

G'day Bruce! Aussies aren't just smart with the Physics

Aussie philosophy faculties are second to none!

Where's the Python icon?

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Joke

Bending light

If there bending light and if I understand you correct its like a curveball then I hate to say it - what goes around, comes around and in this case wouldn;t you haev the light going only faster in a circle and as for relative direction it wouldn't be faster. Now unless your talking about light that bends and then instead of bending back upon itself it bends the other way as in taching with a sailboat. Then could we not call it tachyon :).

Also under the laws of relativity would it not be easier to bend the observer than to bend light :).

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Anonymous Coward

That would have to be a

Tackyon to get the correct spelling ( to tack a boat ). But it all sounds a little, er, tacky

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Headmaster

Tachyon

Tachyon from the Greek just means "fast particle" and is used to name particles that travel faster than light, as in the old joke:

Q.: Why did the tachyon cross the road?

A.: Because it was already on the other side.

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Hmmm

One word: Amazing!

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Meh

Disappointing

I was hoping that someone had discovered a way to supplant supermassive blackholes into chips. Back to the drawing board I guess.

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Ru
Boffin

Why supermassive?

A black hole of any size is capable of bending light by definition. You could presumably have an optical chip that only weighed a few thousand tonnes if you used suitably lightweight singularities, with the added advantage that the event horizon would be confined to your computer.

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Trollface

Mr

"the event horizon would be confined to your computer" ...for a while anyway. These things have a habit of growing.

<--- unlike trolls, you can't not feed a black hole.

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Trollface

Submitted academic papers covering their work

This is all well and good but have they applied for a patent yet?

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letters, digits to follow.

No, but ill bet Apple has :)

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Devil

Re: letters, digits to follow.

At Apple, if the hidden microphones pick up the words "that would be nice", the legal department is immediately notified and a patent application fired up.

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Single asterix

I thought that the gravitational field of a star bent/distorted space time, not light, so this is in fact rather different and new, pretty cool.

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Asterix?

Maybe it's Obelix' gravitational field?

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Ultimately it's just semantics

But if spacetime is warped or "bent," and light follows the curvature of spacetime, then I think it's ok to call it bent. Some might get upset by this flaunting of "light always travels in a straight line", but the alternative is to require some clumsy, narrowed definition of the simple word "bent".

It is also referred to as "lensed" by astronomer types, as in "gravitational lensing," even though it is not actually being refracted.

Still - as you say - this is not that, but rather a newly minted form of cool.

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Ground effect with light?

Probably as over-all useful as an ekranoplan, then?

Cool, but outside of academia probably not exactly handy ...

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> but out of Academia no exactly handy

What use is a new born baby?

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@JimC

"What use is a new born baby?"

Not much. Babies are a drain on the entire community, by definition.

Why? Because we have to teach them how to do simple stuff like copy & paste material for subject lines ...

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Boffin

Bendy bits

Excuse my ignorance, but if the light is being bent, does that mean the light on the outside of the curve is going faster than the light on the inside of the curve?

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The light on the outside

No. Think photons.

We already bend the path of photons by passing them obliquely through a progressing change of refractive index. So lets not worry about the inside and the outside track of the particle.

The most common example of this is sunlight entering our planet's atmosphere.

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Boffin

Is all an ilusion...

Light is not made of lines but of individual pieces.. photons.. so

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Headmaster

Mr

Surely that isn't the most common example. Of all the photons in the universe, hardly any go anywhere near our planet's atmosphere.

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Coat

stars don't bend light.

They warp spacetime. This is why the light appears to bend. It is still travelling in a straight line, but through warped space.

Ahem.

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Headmaster

So what is different between a straight line in warped space and a warped line in straight space?

The distinction you are trying to draw is meaningless. In a relativistic spacetime, light travels along *geodesics*. Any attempt to distinguish between the two hypothetical cases you define is meaningless empty semantics.

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Trollface

Like a record, baby

Better get creative quick on how this thing might destroy us all™. Think of it this way -

1. Lets put a lot of bendy light in a field someplace.

2. Since it's bendy it's bound to go in a circle.

3. ???

4. No more need for long exposure flashlight photography!

Also, scientist... get real! You aren't doing this for applications, you just want something cool to play with.

Also, where's the Dr. Stragelove icon?

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Good article.

And very interesting. You've done a fairly good job of keeping the pedants at bay, but I must take issue with your assertion that the acceleration is "in the direction of the curve". Surely that would indeed cause the light to accelerate beyond C. Is the accelleration not towards the focus of the curve? Isn't it analagous to centripetal accelleration?

Or am I being too picky?

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Think vectors

It'll accelerate in a slightly different direction than the one it was going in.

c is a constant. The direction in which it is moving at speed 'c' is not.

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Boffin

Not sure about being too picky, but...

The term "acceleration" is used wrt vectors - the light has both velocity (c), and direction. The velocity remains the same around the obstacle, but the direction changes - and a change in the direction of a vector is termed acceleration, even if the velocity remains constant. A change in velocity without a change in direction is also termed acceleration.

A scalar is like a vector, but without a direction - hence a change in direction of a scalar does not result in acceleration.

I hope that's all correct. It's been along time since first-year physics, but I stumbled over "acceleration" being a change in direction of a vector at first.

I don't have an answer to the question about whether the outer edge of the beam travels faster than the inner edge, will be interesting to get clarity on that point. Maybe the beam velocity remains at c for all points on the curve, resulting in a beam with a slanted leading edge, instead of straight?

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Boffin

Picky Picky Picky

If we're being picky here, velocity is also a vector - speed is a scalar. So while the speed of light (in vacuum) is a constant, the velocity aint necessarily so

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That is of course, entirely correct.

My grasp of the correct terminology is clearly a bit rusty.

Vector = speed with a direction. Velocity is a vector.

Scalar = speed without a direction. Ones' respective economy/government/Republican Primaries is a scalar.

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Headmaster

If by "slightly different" you mean "at right-angles to it", then yes.

OP was completely right, the direction of the acceleration is toward the center of the hypothetical circle. I can't tell whether ElReg's wording was slightly loose, or if the actual intent of the article was to suggest that the acceleration would be tangential, which would indeed be incorrect.

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Devil

Tron?

Bendy light makes me think of LightCycles in Tron. I'd always play the blue guyhttp://www.theregister.co.uk/Design/graphics/icons/comment/devil_32.png

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WTF?

Vectors

Bit early in the morning for me, late night, but.

If the light is moving forward at the speed of light and is being accelerated downwards, say, then by adding vectors wouldnt the light be travelling fast than, well, light?

Clearly this is not true so I must be missing something, I did say I had a late night.

Ridley

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Boffin

turning

When you turn the wheel of your car, you accelerate toward "a" center, it doesn't mean your car goes faster. That's because the direction of the acceleration constantly changes as well.

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Facepalm

Thanks

for making me feel stupid.

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Pint

So An Airy Beam Is A...

...wavelet.

http://focus.aps.org/story/v20/st19

"To make the beam, the researchers directed a centimeter-wide laser beam onto a watch-sized liquid crystal display screen called a spatial light modulator (SLM). The reflectivity of each pixel on this screen is related to its index of refraction, so the device allows control of the precise phase of light reflected from each spot."

It seems to me, a Sony SXRD or suchlike might do for experimentation.

The reflective surface of the LCD screen, just like a lens or a diffraction grating, is a special case of a hologram.

The individual photons in an airy beam do not travel in a curve. The gravitational field of the lens/grating/pinhole/hologram bends spacetime.

An airy beam is a hologram of a curved line; it can as easily be a data frame. Inside an optical chip, the individual bits of this data frame can be instructions or data. The energy of the light itself can be made to operate switches, etc. without an intermediate "electronic" step.

The output of the chip might be an array of modulated reflectors on the surface, "read" by a laser beam reflected into the next device. Certainly faster than liquid crystal.

More on wavelets at http://www.tinaja.com/wave01.asp

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So An Airy Beam Is A... wavelet

No, it isn't. True Airy beams are very non-local, and in fact (crudely speaking) the reason they don't diffract is that they're already spread out enough (and in the right way) so that the light diffracting out from the middle of the beam is exactly balanced by the light diffracting back from the edges.

A wavelet is a localised mathematical object, useful as a basis with which to describe similarly local, oscilliatory thing - e.g. light beams or pulses.

You could describe arbitrary beams in terms of a basis of "Airy modes", but the Airy functions aren't local enough to match with the wavelet concept.

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Anonymous Coward

"The gravitational field of the lens/grating/pinhole/hologram bends spacetime."

What !

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@Paul @ac

Thanks for your insight.

http://www.tinaja.com/glib/hack77.pdf Article starts in column2.

A soliton is a wavelet that has been Pre-Distorted to preserve information traveling through dispersive media. Don Lancaster gives us the example of a chirp, "Bats and military radars use a more elaborate chirp scheme that works in more or less the same way as do the solitons.

Send any swept FM signal through any media that has a linear delay versus frequency response, and you get a narrow and high amplitude pulse back out."

Similarly, an Airy Beam is pre-distorted (in the spatial instead of frequency) domain to prevent dispersion.

So I should have said An airy beam is <i>like</i> a Soliton.

@AC "The gravitational field of the lens/grating/pinhole/hologram bends spacetime." This statement was intended to reinforce that the photons are going in a straight line, but space is curved by the various optics. It was appropriate in describing how Airy Beams are formed, but not the beam itself, which is described in the next phrase "An airy beam is a hologram of a curved line..."

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"but space is curved by the various optics"

This is nonsense !

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Anonymous Coward

@@AC

The reason for light being bent by lenses is well understood and has nothing to do with spacetime bending. It's a purely electromagnetic process. Ditto for diffraction.

NOTHING to do with gravity.

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Skin Effect?

Have they not simply demonstrated skin effect at light frequencies? Or fluidics for light? In any case if light is being bound (however it is done) to the "surface" of a substance then there must be some kind of "resistance" involved. Which implies that the light will not be travelling at C and therefore is perfectly capable of accelerating round a curve.

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Happy

@ It wasn't me

Hiya bud, just to clear this up:

When the author wrote 'accelerate' he is referring to a change in velocity, not of speed. The difference is that velocity has a direction component, a vector. Thus a braking car can be said to accelerating.

And a car driving around a roundabout is accelerating at constant speed- though its velocity is constantly changing.

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Specifically: if the acceleration vector is (& stays) perpendicular

to the velocity vector, the object will change direction but not speed.

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But...

Yes, yes, this Airy beam is all well and good but what I want to know is....will it bend. Well yes, yes it will!

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Coat

Two of the four groups

The original article of course having been written by The Great Lobachevsky

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Facepalm

So, what happens if the photons get lost on the way?

"I knew I shoulda taken that left turn at Albuquerque!"

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