How Does Television Stone Work?

Summary

The video explains the interesting optical properties of ulexite, a mineral nicknamed 'TV rock'. Ulexite can visually mimic images of objects placed underneath it due to an internal fiber optic-like effect. Light enters ulexite crystals at specific angles enabling total internal reflection along microscopic parallel tubes, transmitting a coherent image to its surface. The unique crystal structure also splits incoming light into defined pathways, emitting multiple conical beams that reveal themselves as rings of light. This generates ulexite's unusual ability to project layered images like a natural fiber optic cable and display.

Takeaways

• 😲 Ulexite is an optical mineral that can mimic whatever surface it is placed on, making it look like a 'chameleon rock'
• 🔍 The image seen on the surface of the ulexite is actually coming from the surface below it, as if the rock is a screen displaying the image
• 👀 The ability of ulexite to transfer images is due to tiny hair-like fibers inside that act as fiber optic cables to channel light
• 💡 The light transfer happens through a process called total internal reflection, based on differences in material densities
• ⚖️ Total internal reflection depends on the angle at which light hits the surface between two materials
• 📐 There is a 'critical angle' at which all the light is suddenly reflected instead of transmitted
• 😎 The fibers in ulexite act like glass fiber optic cables to bounce light through tiny high density crystal tubes
• 🔬 When laser light shines through ulexite, it often forms rings or cones due to the round shape and varying densities inside
• 🌈 Ulexite can split light into multiple cones because it is birefringent - its crystal structure has 3 different refractive indices
• 🤓 The discovery of image transfer through ulexite preceded research into fiber optics by about 80 years

Q & A

What causes the unique optical properties of ulexite?

Ulexite has a fibrous internal structure made up of tiny aligned crystal tubes that act like fiber optic cables to transmit light via total internal reflection.

How is the image transfer ability of ulexite different from transparent materials like glass?

Unlike transparent materials like glass that just let light pass through, ulexite actually transfers the image from the surface it is placed on to its own top surface, as if it is a screen.

What causes light to be partially reflected at an interface between two different materials?

The difference in densities between two materials causes some of the light to be reflected back when hitting the interface, while some is transmitted through. This partial reflection occurs due to light being an electromagnetic wave.

What is the critical angle and how does it relate to total internal reflection in ulexite?

The critical angle is the angle at which 100% of light hitting an interface gets reflected back instead of passing through. In ulexite, the crystal tubes use total internal reflection to bounce light down their length.

Why does shining light through ulexite sometimes produce ring-shaped outputs?

Due to the asymmetric crystal structure of ulexite having different refractive indices, exiting light rays are bent differently, producing cone-shaped outputs that appear as rings.

When was ulexite first discovered and when was its light transmission ability studied?

Ulexite was first discovered around 1840 but its fiber optic-like abilities weren't studied until the 1920s when total internal reflection in crystals was beginning to be understood.

How does the fiber optic-like behavior of ulexite relate to its molecular structure?

The tiny aligned crystal tubes of ulexite act like glass fiber optic cables to transmit light, producing optical effects related to the asymmetry and variations in the crystal structure.

Why does ulexite display images from surfaces it is placed on?

The dense crystal tubes transmit surface images via total internal reflection, causing the top surface of the ulexite to display whatever is below it.

What makes the image display ability of ulexite different from a typical transparent material?

Unlike a transparent material that just passes light through, ulexite actually transfers and displays the surface image on its top side due to its unique internal light transmission properties.

Why weren't ulexite's fiber optic-like properties understood earlier?

The fiber optic abilities of ulexite were not studied until the 1920s, even though it was discovered in the 1840s, because total internal reflection in crystals was not yet understood.

Outlines

00:00

😲 Ulexite stone acts like an optical display

The ulexite stone can optically mimic whatever surface it is placed on, making it look like a thin display or screen. This happens due to tiny hair-like fibers inside the stone acting as fiber optic cables to transmit light via total internal reflection. The effect makes the thick stone appear to have no depth.

05:01

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Keywords

💡ulexite

Ulexite is the rock that is the main topic of the video. It is described as a "chameleon rock" that optically mimics whatever surface it is placed on, making it look like a screen displaying the image below it. This unique optical property is explained later in the video.

💡total internal reflection

This is the key phenomenon that allows light to transmit through the fibrous structure of the ulexite rock. It occurs when light hits the boundary between two materials at a specific angle called the critical angle, causing it to be completely reflected instead of refracted.

💡fibers

The ulexite rock contains hair-like fibers made of crystalline structures. These fibers act like fiber optic cables to channel light via total internal reflection, carrying the image from the surface below up to the top surface of the rock.

💡critical angle

This is the specific angle at which total internal reflection occurs when light passes from a higher density material like glass or crystal to a lower density material like air. Light approaching the surface interface at this angle gets completely reflected back into the higher density material rather than exiting.

💡refractive index

This refers to the speed at which light travels through a material. Materials with different refractive indices, like glass and air, cause differences in light reflection and refraction at their surface boundary. Ulexite has three different refractive indices which splits light into "fast" and "slow" rays.

💡fiber optic cables

The hair-like fibers in ulexite rock work by the same principle as manufactured fiber optic cables for transmitting images. This property of effectively channeling and displaying images gives ulexite the nickname "television rock".

💡electromagnetic wave

Visible light behaves as an electromagnetic wave. So when light waves encounter a boundary between materials of differing densities, some of the wave reflects and some passes through to the next material. This explains the partial reflection and transmission of light at material interfaces.

💡birefringent

This term means having two different refractive indices, which is the case for ulexite crystals. Birefringence causes incoming light to split into two polarized ray bundles with different speeds. This creates the interesting visual effect of multiple rings of light exiting the material.

💡ray tracing

This refers to graphically mapping out the paths of individual light rays to study reflection and refraction effects. Ray tracing is used in the video to illustrate how light reflects within the needle and ulexite rock to form the ring patterns.

💡refraction

When light travels from one transparent medium into another, it changes direction slightly, which is called refraction. The amount of bending depends on the refractive indices of the two media. Some light also reflects back. Together, reflection and refraction explain the complex propagation of light.

Highlights

Ulexite optically mimics whatever it's placed on, making it look like a chameleon rock.

The image seen on ulexite's surface is actually coming from below, as if the rock is a screen displaying the image underneath it.

Ulexite fibers act like tiny fiber optic cables, transmitting light from below to the surface through total internal reflection.

Total internal reflection happens when light hits between two materials with different densities at a specific "critical angle".

The ulexite crystals act like densely packed fiber optic cables, allowing an image to be transmitted clearly.

Ulexite's image transmission abilities were known since the 1800s, but how it worked via fiber optics wasn't understood until the 1920s.

Due to the fibers, light exiting ulexite forms a ring pattern rather than a solid circle.

The ring pattern happens because the exiting light rays form a cone that appears as a ring shape on a surface.

Multiple refractive indices in the ulexite crystal split light into "fast" and "slow" rays, forming multiple rings.

Sponsor highlight: Teemu has surprisingly good quality products at extremely low prices.

Light shining through a round object exits in a "V" shape from different angles, forming a cone and ring shape.

You can see the ring patterns by looking through the ulexite stone itself.

Ulexite's three different refractive indices bend light into "fast" and "slow" rays.

The ulexite crystal structure is asymmetric, leading to differing refractive indices along different axes.

Unique crystal structure and optics make ulexite an interesting and visually compelling natural phenomenon.

Transcripts

this is a rock called ulexite It Can

optically mimic anything that it's

placed

on look how it matches exactly what's

below it no matter where I put it it's

like it's a chameleon rock or

something it looks different than

something that's transparent like this

glass cube here notice that with the

glass cube you can easily see that

there's a stone below it that's shining

through the glass but with the UI it's

different the image is actually coming

from the surface of the stone the stone

inherits whatever image it's placed on

almost like it's a screen displaying

what's below it look how weird this

looks on the

carpet it looks like it's really

thin whereas compared to Glass you can

tell there's a material on top of it

kind of squishing the carpet it doesn't

look the same it's like we're watching a

screen displaying the footage from a

camera being pressed against the

material and for that reason people call

you Lex site television stone for

example look how cool it looks when I

set it on my phone it's as though the

stone is now a TV screen but really it's

just displaying what's below it this is

so cool because it transfers the image

to the top of the stone it makes it look

like the stone has no thickness like I

just put a thin plastic sheet in front

of my phone but it's actually really

thick well if you look at the side of

the ulx site you'll see that it looks

like there are a bunch of tiny hair like

fibers these fibers act like tiny little

Fiber Optic Cables so the light that you

see on the surface of the stone was

actually carried through these fibers

which act like tiny little pixels

similar to if you had an array of fiber

optic cables the way the light transfers

through these fibers is called total

internal reflection this happens when

light hits the surface at an angle

between two materials that have

different densities let's look at this

Ray simulator to show you I'll put some

glass on the bottom and air on the top

top notice that as I have this single

ray of light aim straight up it just

exits the glass but notice there's a

tiny little bit of light that gets

reflected whenever you have light moving

from one material to another that has

different densities there will be some

light that gets reflected back and some

light that gets transmitted this happens

because light is an electromagnetic wave

when a wave is moving through a material

that suddenly has a different density it

partially acts like a boundary that it

bounces off of you can see these waves

bouncing Within wave for example if I

take this Slinky I can wiggle it and

make a wave move down the slinky but if

I change the tension in the slinky at

one spot by putting this bar here then I

have one section of Slinky that's more

dense than the other so if I make a wave

moved down it you can see that some of

the wave passes through the boundary and

some gets reflected that's what happens

with light too with the light the amount

that gets reflected is very dependent on

the angle the light shined notice that

as I change the angle suddenly the light

doesn't ever exit the glass and it's

100% reflected this angle where it

suddenly gets 100% reflected is called

the critical angle you can see it easily

with this glass cube and a laser here if

the angle's too great then most of the

light exits the glass but if you get too

shallow suddenly it just reflects like a

mirror the ulexite just has a bunch of

long tubes of high density crystals

similar to Glass Fiber Optic Cables so

the light just bounces through the tubes

and exits because the tubes are so tiny

packed together we can see a picture

that's pretty clear if they were bigger

we wouldn't see a clear picture the

ability for uite to transfer an image

from the top to the bottom has been

known since its Discovery around 1840

but no one really looked into how it

worked so this was literally a fiber

optic cable right in front of their eyes

for everyone to see but it wasn't until

the 1920s before anyone started

understanding that crystals and glass

can transmit light through total

internal reflection like this because

because of the fact that these are tiny

little tubes transmitting the light

there's another weird thing that happens

to the light that comes out of the

fibers if I shine a laser light through

the rock it kind of does what you'd

expect and comes out as a bigger dot of

light on the back here but if I just

change the angle of the beam slightly

then the light is only concentrated on

the outer edge of the circle and it

makes a ring or in other words it makes

a cone of light that's empty in the

center if you change the angle a bit and

move to different places you can see two

or even three rings of light so why

would it make a ring of light well let's

start off with just the single ring

let's take something that we know is

round and reflects light off the sides

like this needle here if I shine the

laser through this needle I also get a

ring of light that appears but why is it

an unfilled Circle why isn't there

anything in between well let's do some

Ray tracing and see what's happening and

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let's get back to the experiment let's

say that I take a slice of our needle

and just look at it in two Dimensions

you can see when my light shines

straight through nothing interesting

happens but when I turn the light

slightly then it splits the light up

into a vshape this happens because at

the exit of the needle one part of light

is coming from One Direction and the

other part is coming from the other

direction so it splits it up now this V

is in two Dimensions if it were a real

needle then that V would become a cone

and when you shine a cone of light on a

wall it makes a ring so that's why we're

getting this ring shape but why can we

see multiple Rings well that's because

UI is TR Clinic meaning that its Crystal

isn't symmetric if you look at its

crystal lattice a doesn't equal B and B

doesn't equal C this makes the crystal

actually have three different refractive

indices so when you shine light through

the crystal it gets split up into rays

of light that are fast meaning it took

the path that had the lowest refractive

index and then slow light that took the

path that had the highest refractive

index because of these different

refractive indices it bends the light

slightly different when it exits the

tubes so the angles aren't the same so

the cones are split up into fast and

slow light you can even see these rings

when you look through the stone as

well and thanks for watching another

episode of the action lab I hope you

learn something if you haven't

subscribed to my channel yet remember to

hit that subscribe button and we'll see

you next

time

[Music]