this post was submitted on 18 Oct 2023
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Researchers studying photonic crystals say they have successfully created a form of pseudogravity that bends light just like real gravity. The new technique could have a dramatic effect on advanced communication technologies like 6G, as well as other applications in optics and materials science that could benefit from a no-contact method of manipulating light.

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[–] ubermeisters@lemmy.world 59 points 1 year ago* (last edited 1 year ago) (2 children)

Photonic crystals are optical nanostructures in which the refractive index changes periodically². This periodic change affects the propagation of light in a similar way to how the structure of natural crystals gives rise to X-ray diffraction and how the atomic lattices (crystal structure) of semiconductors affect their conductivity of electrons².

Photonic crystals can be fabricated for one, two, or three dimensions. One-dimensional photonic crystals can be made of thin film layers deposited on each other. Two-dimensional ones can be made by photolithography, or by drilling holes in a suitable substrate. Fabrication methods for three-dimensional ones include drilling under different angles, stacking multiple 2-D layers on top of each other, direct laser writing, or, for example, instigating self-assembly of spheres in a matrix and dissolving the spheres².

Photonic crystals can, in principle, find uses wherever light must be manipulated. For example, dielectric mirrors are one-dimensional photonic crystals which can produce ultra-high reflectivity mirrors at a specified wavelength. Two-dimensional photonic crystals called photonic-crystal fibers are used for fiber-optic communication, among other applications. Three-dimensional crystals may one day be used in optical computers, and could lead to more efficient photovoltaic cells².

In essence, photonic crystals are materials patterned with a periodicity in dielectric constant, which can create a range of 'forbidden' frequencies called a photonic bandgap. Photons with energies lying in the bandgap cannot propagate through the medium. This provides the opportunity to shape and mould the flow of light for photonic information technology⁵.


Source: Conversation with Bing, 10/18/2023 (1) Photonic crystal - Wikipedia. https://en.wikipedia.org/wiki/Photonic_crystal. (2) Photonic crystals: putting a new twist on light - Nature. https://www.nature.com/articles/386143a0.pdf. (3) . https://bing.com/search?q=photonic+crystals. (4) Introduction to Photonic Crystals: Bloch’s Theorem, Band Diagrams, and .... http://ab-initio.mit.edu/photons/tutorial/photonic-intro.pdf. (5) Photonic Crystal Research - Massachusetts Institute of Technology. http://ab-initio.mit.edu/photons/


"Pseudogravity" my ass. The science is interesting, the headline is clickbait.

[–] Varyk@sh.itjust.works 33 points 1 year ago (3 children)

So this is complex refraction, not any form of gravity?

[–] subignition@kbin.social 31 points 1 year ago (1 children)

Crystals With No Relation To Gravity Whatsoever Produce A Similar Effect To One Of The Things Gravity Does (They Bend Light) doesn't roll off the tongue

[–] Varyk@sh.itjust.works 22 points 1 year ago

I would gladly accept the extended headline in place of such an asinine misguidance.

Thank you. I did say that out loud and it was very funny.

[–] ubermeisters@lemmy.world 8 points 1 year ago (1 children)

That sure what it sounds like to me, but the science is way above me

[–] AA5B@lemmy.world 3 points 1 year ago* (last edited 1 year ago) (1 children)

Consider eyeglasses. I have very thick glasses that help me focus by using lenses with different refraction than surrounding air to bend the light. Do I use pseudo-gravity to see?

Then most of the article is about really cool functionality described similar to some electronics basic operations that could potentially grow into logic gates or switches, which would be very cool, and still has nothing to do with gravity.

[–] ubermeisters@lemmy.world 3 points 1 year ago

Refraction=/=gravity

Hard agree

[–] BloodSlut@lemmy.world 2 points 1 year ago (1 children)

And "without contact"?

I dont know, but i think light has to pass through something for refraction to actually mean anything

[–] Varyk@sh.itjust.works 2 points 1 year ago

Thank you BloodSlut, that's a good point. It's hard to nail down though because it's the physical shape of crystal that's bending the light but it is equally important to note that it does not contact...but isn't that what refraction is?

So even though the light is technically passing through the crystal, well, I guess that is still refraction isn't it? It's complex refraction because it's being made to travel through the substrate in a particular way unlike the common way light passes through crystals.

a facilitated, specialized refraction.

But I guess since it bends light in the shape that light would bend around an object for to gravity they're calling It pseudogravity, even though that's sort of like calling a sea turtle a pseudoshark since they both move through water even though their movements are based on different properties.

Or maybe like calling flailing your arms while drowning pseudoswimming, since the motions are similar but the reason for those motions occurring are totally different?

Thanks for bringing up the no-contact thing.

[–] Salamendacious@lemmy.world 5 points 1 year ago (1 children)

Is it any more egregious than the Higgs boson being called the "god particle?"

[–] ubermeisters@lemmy.world 27 points 1 year ago (2 children)

That's because Leon Lederman called it "the goddamn particle" and the media opted to drop the damn

[–] Salamendacious@lemmy.world 3 points 1 year ago

The media got it from the title of his book