"it didn't blow up and kill me, so huge thanks to Ben"

2022 Nilered/blue: "I've been thinking a lot about fission bombs. The materials for that are really expensive but... I bought some."

I love it when a scientist says "I have no idea what's going on." That's when REAL science happens.

The Beads suffered "Thermal Shock" which resulted in them shattering internally. Those iridescent looking bits are the surfaces of internal fracture plains refracting the light. You can often see this in natural crystals (eg: Quartz).

Ben: "it's somewhat dangerous and might explode if you aren't careful" Nile: *shakes it around in his hand while it's pressurized*

"and it didn't blow up and kill me so.." that's what I love about science.

NileRed: strict and is usually safe NileRed Shorts: has a little fun, and edges the line of dangerous NileBlue: "I've been thinking alot about Neutron Bombs, the materials for that are really expensive, but..."

That multicoloured opal-like feature in the silica crystals is called the Schiller Effect. It’s common in a lot of gemstones.

“Let me pay for shipping” “no.” “But i-“ “no.” “Come on Ben.” “nope.”

Awesome!! I'm glad the chamber is serving you well. Your videography skills are outstanding, and have such a recognizable style. I'm also glad the chamber didn't explode on you :)

Watching Niles videos is like watching a suspense movie where you know the hero survived (because otherwise he wouldn't have been able to make and post the video).

The cracked silica beads would probably look pretty interesting under a polariscope. Also having one is useful for seeing stress in your glassware so it might prevent the need to smash all your beakers again in the future.

"This thing is practically a live bomb" *starts violently shaking it*

NileRed: this is basically a bomb also NileRed: *shakes it

I love how he goes from being really cautious with the chamber to shaking it violently like 10 minutes later

i used to work in the compressed gas and cryogenic liquid industry. my manager told me of a story once where an entire semi-trailer load of liquid CO2 was lost because the driver left the pressure relief valve open, and it all turned into a block of dry ice. that sounded like fun times!

NileBlue: “I did a pressure thing and it didn’t explode so I shook it around. It still didn’t explode so I shook it harder. It was still fine so I came in with a hammer-“

NileBlue’s channel in a nutshell: “he warned me that in theory it was kind of like a bomb and it could explode at any time, but it should be safe”

Nice seeing this video featured in PBS Space Time! I've always wondered why supercritical fluids exist, and what they are like.

It looks like the liquid slowly changes refraction index, until it becomes invisible to the eye. Stunning

Opal is literally what you describe, hydrated SiO2 put under geological pressures, so congrats on making synthetic opal

When I saw the title I thought: "Oh, hes making a nuclear bomb"

8:10 This looks really cool. It's like you can still see the liquid but on the boundary it looks like it's both gassy and liquidy at the same time.

This is actually really cool to see on KZfaq. Something that usually is done behind closed doors in a windowless chamber. It's all well and good studying graphs and reading text explanations, but it's so much better to see it changing state and going supercritical in person.

The rainbows look really similar to the rainbows found in stress-fractured Quartz. The rainbows are probably caused by the cracks made by a very high pressure environment.

This man put silicates into a pressure chamber and is suprised that he accidentally made artificial gemstones. Edit: The comments are a trainwreck and really aren't worth reading anymore, since the main antagonist who started it all has since left. Read at your own risk. Edit 2: 3 years later we find out he was banned lol. Have fun reading these

The rainbow iridescence is just light refraction between fine fractures. Light is passing through the fracture, but is split as it reflects off the conchoidial fractures (between the fractures). Opal has a similar iridescence, but opal is reflecting light through water trapped in its crystal lattice. There is quartz which is sold as jewelry and trinkets which have been stressed to a point of internally shattering. It is often referred to as "crackle quartz". That's pretty much what you have created :) Edit: as for the discoloration, would bet that it is carbon which is trapped in the microfractures. I wonder if the silica (silicon dioxide) could have decarbonated the carbon dioxide under those supercritical conditions and trapped some of the carbon as a precipitate inside the silica. Just a thought. The only other thing that changes silica brown (aside from impurities) would be irradiation (such as smoky quartz), but I don't know that supercritical CO2 is radioactive, or that it would have an irradiating effect of any kind.

I've been watching the videos on this channel for last couple weeks and I didn't realize this was the second channel! Excited to catch some cool videos on nile red

Hey I’m a bit of a gem nerd, I know that there are other comments but I felt like giving you my opinion. Using silica and introducing it to high pressure and temperature is exactly how synthetic or man made gems can be made. Specifically I’m going to quote milky/greasy quartz first as it’s a silica that’s introduced to co2. “Milky Quartz is Trigonally structured gems are made of silicon dioxide, their full chemical compound being SiO2. Milky Quartz is a milky white translucent to opaque variety of crystalline quartz of somewhat greasy luster. It is the commonest variety found in pegmatites and hydrothermal veins. The color is generally caused by numerous bubbles of gas and liquid in the crystal. The milky color is caused by small cavities filled with numerous small fluids and CO2 in liquid condition. It is used as a gemstone, and also called greasy quartz.” Next this is how ‘titanium quartz’ / “aura quartz” is made. “...aura is created in a vacuum chamber from quartz crystals and gold vapour by vapour deposition. The quartz is heated to 871 °C (1600 °F) in a vacuum, and then gold vapor is added to the chamber. The gold atoms fuse to the crystal's surface, which gives the crystal an iridescent metallic sheen.” It seems the process is highly similar. Hope this helps.

"I wanna make aerogel" \*makes 17 minute video of CO2 clouds\* Or in other words: how much i focus on my task every time i try to get shit done

Hi Nile, thank you so much for showing this. I have been working with supercritical CO2 lately to foam polymers. I agree with you about the microcracks forming when rapid depressurizing your chamber. When doing so, the fluid expands so quickly that the silica cracks. I think the coloring comes from birefringence. This is very cool to see. Looking forward to seeing more of your videos!

Thank you for showing and teaching us experiments that we can't see anywhere, thanks to your wonderful explanation and subject choices. I wish you safe work. Be careful

" It should be safe... buthesnotresponsible." LMAO.

15:05 Considering that opal is fractured, water-impregnated silica, the effect might actually be very similar to opal! The cracks are thin enough to refract light and scatter its wavelengths, causing iridescence (like in hummingbird feathers or certain beetle wings)!

Great video! it is so cool to wartch the transition to and from supercritical fluid. Thanks for this!

It would be interesting to see a laser beam going through the fluids and looking at the refraction

Get a torque wrench for the bolts, one of the most handy tools to have.

"in theory it's kind of like a bomb and could explode at any time, but it should be safe!"

Around 10-11 minutes, i find it really interesting how you can see the index of refraction changing and eventually equalizing with the gas

Some of the initial cloudiness that appears when you vent the chamber, depending on the exact temperature and pressure, might be critical opalescence. At the critical point correlation lengths go to infinity, so density fluctuations happen at all scales, so you get a whole bunch of Rayleigh scattering -- the same phenomenon that makes the sky blue. Probably also the reason for the cloudy layer between the soon-to-disappear liquid and gas phases.

“It didn’t blow up and kill me, so a huge thanks goes out to Ben.” Agreed.

"It could explode at any time and it's kind of like a bomb but... it should be safe."

This is so f-ing cool. Please never stop making content!!!

My favorite experiment you've done so far!

It's so beautiful! At 13:40 you can see a perfect example of Rayleigh scattering. First you can see a flash of blue haze (particles less than 1/10th of a micron = Rayleigh scattering) which quickly turns into 'white clouds' (particles larger than 0.5 microns) which is in the Mie scattering domain. You should try to shine a white light through it from behind whilst going through the Rayleigh scattering phase - the light should turn orange (just like during the sunset). It's like you have a sky in a jar.

Nilered: *strict* Nilered shorts: let’s do fun stuff but also be safe! Nileblue: M E m E s

The light bending shifted as it went super critical around 10:40. That was interesting to watch. You can see the distortion on the back nut starts with a hard crease, which softens, rounds out, then disappears

Thank you for doing what you do it sounds so interesting and very Intriguing and what you guys do . Have a blessed day. I’m from an Alaskan Island horn and raised tell I loved to pnw in 2020 still not have adapted. As others have wanted me to fail.

13:44 "Mirror mirror on the wall, show me a random pile of silica pellets."

When you’re tightening bolts on something like this, do one and then the bolt directly across from it. Repeat until all are tight. That’s the safest way with high pressure applications.

This is very interesting and helpful for me! Working in Refrigeration with Co2 as refrigerant since last April.

These are some really precious footage. I kinda feel impressed that science is no longer exclusive to scientists locked behind lab doors of cooperation or institutions. Instead people could conduct different scales of experiment, catalogue their observations and contribute to our species' understanding of this universe. And more amazingly, these results can be easily accessed via internet. Great video!

17:41 lol I didn't even notice this wasn't your main channel until you mentioned it

I love how nonchalantly you mention that it could just explode in your face

Love your work man. As for the beads at the end, that's structure created by chemistry. It seems to me that the pressure made the co2 sneek in and interaction with soluble silicates created this crystal lattice. Imagine polishing it and peering in it like a gemstone. I hope you make such a video. Cya;

Try slowly venting it to avoid cracks to see if film interface or crystalline structure

Nile : "Going supercritical ..." Me : Waiting for 2 Plutonium half balls and a screwdriver ...

I love science cause anytime that the phrase “it didn’t blow up and kill me” is applicable means there’s som cool shit going on

I've never thought of it before, but usually people think of phase changes as linear. That's how I generally think of them too even though I've seen live demonstrations using dry ice and I'm familiar with concepts like the triple point. I didn't really hit me until I was watching this video that solid CO2 is called dry ice because it doesn't ever get wet. It skips melting and goes straight to evaporating. That sounds obvious, but I guess even something obvious can go unnoticed if you just never think about it. I appreciate videos like these that help me get a better understanding of topics like these :)

I see a pair of JBL LSR305s!!!!! I have them too. Amazing monitors. No matter where you stand in the room you can hear both them. Amazing stereo image and very clean accurate sound. JBL Professional is good stuff. Huge respect Nileblue!

"It's kinda like a bomb, and could explode at any time" I was gonna say that you're gonna be on a list, now - but lets be brutally honest... You've been on that list for YEARS. ;)

As a physicist I can tell you you made a "photonic crystal" out of those beads (that's the theoretical name of this particular object). What's happening is that the micro-cracks induced in the spheres by the stresses have a very fine and ordered (quasi-periodical) structure; as a result some wavelenghts cannot propagate through that structure and get reflected (the real underlying mechanism has to do with the regular structure creating a bandgap in the phonon dispersion structure of the material if I'm not mistaken, but I'm not an expert). It is through that mechanism that all iridescent butterflies get their colour, and indeed an opal is another sample of natural photonic crystal. Btw, photonic crystals are widely used in modern technology due to their very peculiar properties.

My guess, these tiny crags in those silica beads acted similar to a prism, breaking the light. I own a small natural crystal I bought at a souvenir shop over a decade ago during a school trip. That Crystal has a few similar looking crags in it, which, if you position it right, creates some little rainbows in it.

absolutely amazing!

New title idea: “Playing god with the properties of state changes with the ever looming danger of a pressure filled acrylic glass bomb going off in front of my face for views”

Nile : he wouldn’t let me pay for shipping That’s wholesome

The colorfull cracks you saw in your silika beads indeed looked like thin gaps, that have a width in the range of the wavelength of visible light. The same and more uniform you can achieve when you put two supper smooth glassurfaces together. What you will see is called Newton's rings. That was an awesome video and the effect of CO2 gas becoming more dense than the liquid is astonishing. I allready liked it over on Ben Krasnow's channal. I just saw that Black Gryph0n already said the same thing...

Real talk, you get my like, cause that was a dope outro piece of music.

0:19 - Unintentional epic demonstration of how the gravitational constant simply _does not care_ how massive a volume is with regard to freefall. Same envelope, same rate of downward acceleration. It's elegant.

"Going Supercritical" Me: "oh cool he's making a nuke"

This is the perfect procrastination video, I know im supposed to be doing something else but i dont feel guilty about it cause its actually so cool and interesting and i feel like im learning

Very good closing scene. Well done.

Man, everything we learn in high school is either a simplification, generalization or lie.

Chopping ice this year, I fractured a chunk such that a fissure crack inside of a crystal clear block produced a rainbow. I thought it was either acting as a prysm, or the prospect of it being a thin film interference made me giddy. The effect was beautiful! So glad I had my camera, though pictures never come out as good as real life. The internet made me do it: imgur.com/gallery/8WDdHkm Enjoy! I would be curious to hear why people think it is either a prysm or TFI effect we are seeing.

Bit of future advice...if you need to tighten something with relative precision, use a torque wrench. That makes things faster, repeatable and mostly predictable. Also that pressure gauge is designed for gases only and was broke from either the liquid CO2 contact or over pressure/vacuum. You need a diaphragm to isolate the gauge from any liquid.

10:55 "A little bit of pressure" meanwhile it shows 40 bar

10:52 "showing a little bit of pressure" *gage shows something like 25 bar*

CO2 critical pressure is 1070 psi, so it's a nice observation that you'd see the phase boundary re-established where you did. I did my PhD looking at oxidation reactions in supercritical water (much higher temp/pressure so we need sapphire windows, or the like to be able to see the liquid/vapour boundary disappear) so was fascinated with this video - really good job of visualising a really interesting aspect of thermophysical behaviour. I might have been a little more careful with a pressurised container, though!

15:00 the stone "opal" is made mainly out of silica. That silica presipitates out of water and creates microscopic silica crystals that are joined together along with some water molecules. The wired color changing behavior that opal shows it called "iridescence" and in this case it's cause by light shining through the tiny silica cristals and then getting split as it passes through because of the tiny gaps between the crystals. Maybe something similar is happening with this silica beeds, but in this case carbon dioxide molecules got trapped inside of the tiny microscopic cracks that it created, and the light is getting split as it passes through because the gaps are just big enough to only allow certain wavelength to pass.

Nile red is that one science man that fascinates people while also making them completely confused

Ben sure is a nice guy isn't he? He's gotta be one of my favorite youtubers, really wish he made more videos. But I'll take the quality over quantity.

"supercritical" is just such a cool term in general

Star pattern tightening. Very nice!

7:55 Something notable that was mentioned once. The waving that happens with the very still horizon of the liquid and seeing the waves of the liquid take on a turbulent waving cloud formation.

This man doesn’t buy things itself, he buys the material for it and makes it for our entertainment

Nile: casually jostles 5+Atmospheres of pressure in one hand

I just learned about this in chem and now i got recommended the video, cool how stuff works like that

The process you explained with the silica beads would be similar conditions to some rock formations. Aquifers deep underground would slowly fill gaps in rock over thousands of years, then when a magma plume moves up into the crust, those saturated rocks can have all their water vaporized

13:42 Seems like you've managed to create a Stargate.

I get so freaking hyped whenever there's a new video!

It would be interesting to see through this transparent vacuum chamber how supercritical CO2 interacts with light (white, monochromatic, laser ...) and track the viscosity of the substance using magnetic stirrer. Anyway, awesome channels, great work Nile Blue/Red! ❤

Could always use a torque wrench for tightening the pressure chamber to find a baseline and stay consistent

4:25 - Two words for you from your mechanic buddy Trikie_Dik.... TORQUE WRENCH! Hardware has grades or classes (depending on imperial vs metric) and those all have set torque specs where the hardware can be set to maximum tightness without causing damage. Keep in mind your host material being clamped may not be able to withstand those max values - but you can do some trial and error, find the key value for your application, and repeat those steps for future iterations of the same test.

News Headline: "KZfaqr accidentally turns silica beads into diamonds!"

your videos are more educational than any of my lectures or English classes

This is essentially the principle on which refrigeration functions. A sealed system where by means of changing state you can either add or extract heat and transfer it to another location. Albeit in most refrigeration you generallt won't reach the critical point with c02 being an exception.

Who else thought that the thing in the thumbnail was a diamond?

An interesting experiment might be to first shine a laser through the enclosure when it's empty and then later when it's filled with supercritical CO2, and measure the difference in diffraction.

I’m pretty sure what you’re seeing with the opalescent reflection is the after effect of the beads structure compacting while being flash frozen and subsequently shattering due to an overload of physical pressure in a small space - while also not shattering apart. So the hairline film is correct, that’s typically what will cause the rainbow effect.

With the kind of stuff you do, I was genuinely expecting the other type of supercritical