Punching Water So Hard LIGHT Comes Out - Sonoluminescence

today we're going to talk about an experiment that was simultaneously both extremely easy and very difficult and took me five years of messing with it to finally make it work and to be honest I think it's some of the finest wizardry we've done on this channel it involves some of the most interesting physics I've ever worked with and produces conditions that over the span of a fraction of a millisecond range from potentially minus 269 degrees to upwards of 10,000 degrees so what on earth am I talking about this is a flask of plain reverse osmosis water there's nothing else in it no die no other chemicals nothing stuck to the bottom is an ultrasound transducer basically a special plate that will vibrate at whatever frequency we drive it at the more power we put into it the stronger those vibrations get we need to drive the transducer at the resonant frequency of the flask think of this like how an opera singer breaks a wineglass if you hit the resonant frequency it will vibrate in response very strongly and in the case of a wineglass eventually explode and break with everything tuned in the strength of the vibrations perfectly set we suck up a very small amount of water and let it drop fall back into the flask from an inch or two above when the drop hits the water a little bubble is formed and shoots down into the flask but then something weird happens rather than floating back to the surface or popping it just sits mid water suspended by the vibrations this is the same way that acoustic levitation works in air but using a bubble underwater instead of a piece of styrofoam now all we do is turn up the strength of the vibrations a bit until we hit this sweet spot between trapping the bubble and popping it finally we turn off all the lights in the room after a few seconds as your eyes adjust if you look where the bubble is you'll see the damn thing is glowing it looks as though somebody has plucked a star out of the sky and contained it in the flask it's really quite beautiful but of course our bare caveman eyeball can't compete with a hunk of silicon so a two minute exposure with my DSLR and you can see the glowing bubble clearly as well as the flask remember there's no dye or chemicals making this glow all of the energy for the glow comes directly from the sound waves were sending through the flask this is appropriately called sauna essence or light from sound in this video we're gonna go through how I did this as well as why it took so long to make it work even though the setup itself is actually really straightforward we're also going to look at how this glow happens as up until now 13 different theories have been proposed to explain the glow and to this day not everybody agrees of those 13 most have been largely disproven but there are still fervent supporters of even those that most agree are incorrect only two remain and we'll see how both paint a very strange picture of what's going on first how did anyone figure this out in the first place as you can imagine there is no way that anyone would have thought to trap a bubble like this and then wait in the dark to see a glow if they didn't already suspect something was up the first instance of this was by H Frenzel and 8 shoots in 1932 they wanted to see what effect ultrasound had on developing photographic plates but when they took the plates out they noticed that there were distinct areas on the plates that would had been exposed and looked fuzzy eventually they realized that the areas in the ultrasound bath they were using where the pressure was highest was where the plate was getting developed it was eventually established that under sufficient acoustic pressures something called cavitation happens basically the sound shoves the water so hard that little bubbles form and then violently slam closed again a great demo of this is to put a piece of aluminum foil in an ultrasonic cleaning bath the cavitation bubbles that form will literally rip holes in it as they expand and contract over only a few seconds worth of exposure this hold Tony did a great demo of this and I've linked to it in the description so as people started to explore this more they eventually figured out that if you just trap a bubble of gas with the sound waves like you just saw you can make that single bubble repeatedly expand and violently compress down on itself over and over again they found that as the bubble is compressed it eventually releases a single flash of light for every acoustic cycle then it expands bounces a couple of times and then the cycle starts over now the first thing that got me interested in this wasn't actually anything to do with ultrasound but instead with the Internet's favorite murderous crustacean the mantis shrimp these angry little bastards have the most devastating punch in the entire Animal Kingdom and can accelerate their little bowling ball hands with the same force as a 22 the bullet when they punch things the impact is such that it violently forces the water out of the way and you get a cavitation bubble and sure enough you also get a flash of light think about that for a second this little rainbow II bugger can literally punch things so hard light comes out [Music] another similar species the pistol shrimp can shoot a jet of water out of its claw and it too produces both a cavitation bubble and a flash of light and it uses the shockwave created to stun its prey lots of other things produce cavitation bubbles - including the impeller on submarines they produce long streams of bubbles which actually cause enormous amounts of noise as the bubbles collapse and release little shockwaves so tons of research has gone into how you can reduce this to make subs more stealthy when I first heard about this of course it was down the rabbit hole to learn where that light comes from and fast forward five or so years later I can now recreate it in a flask of water now for those of you that saw my cold fire video you know that it took me 18 attempts to get a torch that worked and produced the beautiful glow of cold fire this project dwarfs that I've long since lost count how many flasks have stuck transducers - to make this work and how many hours I've spent in the dark staring at an empty flask of water the issue is that there are several tutorials online but they all rely on doing this in the most difficult way possible and rely on using materials that are only sold from a single company in Germany that isn't super keen on selling you things when the reality is most of that doesn't matter their methods are over complicated - no real benefit and this can be accomplished far more easily the other issue is what I call mount stupid basically when you're trying to learn about something weird and niche like this you don't even know the right words to look up to find the information you need and when you're working from YouTube videos recorded with a rotten potato and tutorials that use materials you can't get that's an issue so hopefully this video will act as a starting point that others can build on and give you the tools to explore this weird and wonderful phenomenon one of the biggest things that made this work was actually a moment of serendipity as I was struggling through this I got an email from the great people over at circuit specialists calm because they wanted to sponsor a video they wanted to send me one of these amazing frequency generator or oscilloscope multimeter things and they wanted me to do a giveaway of a few of them to my subscribers I cannot express how lucky this was as this tool single-handedly was the most important thing for making this work you can actually do the entire experiment using just this as both your signal generator and a cell scope but for the sake of convenience I'll be using a second oscilloscope to make this a little bit faster because of how finely you need to tune the whole set up having a great digital signal generator like this is absolutely mandatory and considering I was using this awful analog thing from the 1950s before this it was a lifesaver so stay tuned till the end of the video where I'll be giving away three of these to a few lucky subscribers but if you can't wait and just want one now use the coupon code thought Emporium to get 10% off site-wide and best of all I've been working with them to put a special page together where you can buy everything you need to do this experiment and has all the calculators you'll need to make some of the components we'll talk about in a moment some components primarily the amplifier and transducer we'll talk about or on order and will be available soon on that page link to everything in the description down below honestly I love this thing and will definitely be using it for a lot more future experiments than just sonoluminescence but for now that's what we're gonna be focusing on the oscilloscope works remarkably well it can produce a huge assortment of signals and works great as a multimeter medi over at electro boom has also used one of these before for another really cool sonic experiment which I've linked to in the description so we've got the thing that will generate the frequency we need now the trick is to amplify it and then feed it into the ultrasonic transducer speaking of which I'm using these dirt cheap ceramic transducer discs that you can get on eBay for a couple of bucks you can also just get one of the big horn transducers that we've used in previous videos and they work just fine the frequencies we're going to be using are pretty close to the audio range specifically about 27 kilohertz so a cheapy audio amplifier off Amazon was all that's needed to do that I'm using a 100 watt one because I wanted to make sure I had enough power but a much less powerful one works just fine in the end we're only really using six or seven watts of power so it's largely overkill I did however add an extra bit of heatsink so I didn't fry the transistors as it did like to get pretty warm so we've got our signal generator or amplifier and our transducer but if we tried to just connect them up nothing would happen the issue is that we need a higher voltage to drive the transducers and they behave like a big capacitor so to drive them properly we need to use a resonant circuit it's the same idea as resonating the wineglass but just with electricity to do this we're using a simple LC circuit which consists of an inductor or a coil of wire and a capacitor in this case the transducer one of the most helpful things to pick up to make this easier is an LCR meter which can measure capacitance inductance and resistance I happen to already have one but circuit specialist carries them if you need one one of the issues with the tutorials I mentioned is they use special tiny transducers from that German company but the capacitance of those transducers and the capacitance of the cheapo transducers that I'm using is not the same so trying to work off the values and those articles will get you nowhere but by measuring the transducer directly we can figure out what its actual capacitance is and then build our circuit around that since we know approximately what frequency we want about 27 kilohertz and now we have a measure of the capacitance in this case seven or eight nanofarads all we need to do is plug that into an LC circuit calculator to tell us how much inductance we need to make the whole thing resonate in this case it said I need about four mil a Henry but that'll just be a ballpark in the end after tuning I found that I only actually needed about three Mulla Henry we can then take this number into an inductance calculator and figure out approximately what size coil will need to give us this inductance the inductance of a coil is set by a few different values the first is the length and diameter of the coil the next is the number of turns of wire and its thickness and the last is something called the magnetic permeability of the core of the coil basically how amicable the core is to letting magnetic fields pass through it the permeability of air for example is basically 1 whereas the permeability of something like ferrite or iron can be 300 or higher rather than trying to make the perfect coil all we have to do is get it below the value we need when assuming there's nothing in the core except air then we can slide in a piece of steel iron or ferrite to slowly raise the inductance until we hit the value we need I ended up using 28 gauge wire and wrapped about 200 turns of wire around an empty spool as I went I just checked the inductance occasionally with my meter as experiment is always better than trying to calculate it when I hit the value I wanted and could insert a steel rod to get that for millihenry value it was ready I added a piece of silicone gasket to the top of the coil so I could slide the metal rod note and we'll hold in place once I've got it where it needs to be now we can wire everything up to help prevent unnecessary EMF radiation interfering with nearby electronics I used 50 ohm coaxial II used for my radio stuff as my wires here's a wiring diagram to show how everything is connected basically the frequency generator is fed into the input of the amplifier the output of the amplifier is connected as some coax and the central line is connected to the inductor we just made the output of the inductor is connected to another piece of coax which can then be connected to our transducer connect the outer shield's of both pieces of coax together and make sure the connections to everything are solid and there's no shorts before we actually connect the transducer though we need to mount it to the flask we're going to be using I mainly focused on replicating what the papers and tutorials used so stuck with a 100 milliliter round bottom flask the transducer was epoxy to the bottom and held in place until it cured once the transducer is epoxy Don solder a wire to each of the two electrode pads carefully and then short the two wires to dissipate any charge that built up from the transducer deforming from heat however one of the papers I linked in the description showed that the flask really doesn't matter and managed functional sonoluminescence in an old-school coke glass and even said they managed to make it work in a wine glass I tried both of these and while I did manage to trap a bubble I couldn't get mine to glow I think it totally would work if you had more patience but by the time I tried this I was pretty sick of sitting in the dark staring at bubbles so gave up point is the round bottom flasks are nice and easy but if you really want to wow your science fair judges or PhD advisor try in a wineglass and don't think that the flask really matters as much as some papers would have you believe but of course changing the shape of the flask and water level will mean messing with the tuning to get it to work speaking of which to monitor what's going on in the flask I broke one of the transducer discs soldered a wire to either side and then epoxy dit onto a random spot on the flask this will act as a microphone and we can use it to measure the sound levels and see how things are working by connecting it up to an oscilloscope which again if you don't have a separate one the scope built into the frequency generator works great for this with a bit of patience okay with that we're almost ready to go the last thing we need to do is D gas our water if there's any dissolved gas left in the water before we add it to the flask it will cavitate all over the place messing with the resonance and preventing the bubble from getting trapped properly the easiest way to do this is to boil our water for 15 minutes at a rolling boil and then let it cool with a lid on the container so it forms its own vacuum however I'm inherently lazy and a much more efficient way to do this is to use a little vacuum pump I'm using a cheap one stage rotary pump I got on Amazon and it works great just let the flask be gas until you don't see any more bubbles forming since I'm using reverse osmosis water it helps to add a stir bar or boiling chips to give the bubbles a place to form easily so this goes faster this is especially important if you plan on boiling it if you also let it stir while under vacuum it goes even faster speaking of water reverse osmosis water isn't strictly necessary I just used it to eliminate as many variables as possible distilled or in some cases even tap water should work just fine just as long as there's absolutely no debris or dust or dirt as this will ruin the effect once your water has been degassed it's good for a few days but considering it only takes a few minutes to Reedy gas it and the effect is much easier when the water is fresh I just make fresh stuff every time ok we're finally ready tip the flask and pour some water in down the side careful not to make any bubbles by accident if you do make bubbles gently tip the flask back and forth to get rid of them fill it so the flask is full up to the neck but not further to hold it I made a little mound out of a piece of acrylic and would that would allow me to suspend the flask by resting it on its upper rim without squeezing the neck but it's not strictly necessary and the usual claw style retort clamps work just don't tighten them down very tight and hold the flask as loosely as possible now we start tuning set the oscilloscope to 1 volt per division and the frequency to around 25 to 27 kilohertz have the power on the amplifier about half way up now watching the oscilloscope adjust the frequency until you see the signal and the scope grow as big as it's going to get there may be several frequencies that do this but check them all and figure out which one gets you the highest amplitude on the scope then once you've found the resonance point slide the metal rod in and out of the inductor until again the amplitude is as high as it's gonna get if the signal on the scope goes off scale turn the amp down a bit if rather than getting a nice clean sine wave if you get weird bumpy Peaks or the trace isn't particularly clean there's still gas in your water and it needs to be D aft better another test to see if things are working properly is by gently squeezing the sides of the flask if it massively changes the amplitude on the scope you're probably near the resonance point now adjust the amplifier until it reads 3 volts peak-to-peak if this doesn't happen either you're not at the right frequency or your inductor isn't at the right value or your water is in D gas properly adjust until it works when everything is working properly you should be able to control the amplitude you read on the scope by just throttling the power on the amplifier and should be able to raise the amplitude until it goes all the way off scale if you can do this it means everything is tuned properly adjust it back down to 3 volts and we're ready for the bubble using a clean pipette or eyedropper suck up a small amount of liquid and let it drop onto the water it helps to have a light shining through the side of the flask to make it possible to see when this works if everything is done properly you should immediately see the bubble get trapped mid water if it shoots off to the side you're not at the right frequency and you need to find another frequency that gives you a bigger peak if the bubble disappears instantly the power is too high and you need to turn the amp down with the bubble trapped slowly turn up the power as you approach about 4 volts will be a point where the bubbles suddenly vanishes turn the power down a hair and make a new bubble if it gets trapped you're ready to take the picture or at least look at it in the dark if not turn it down a bit more and try again now the hard part is that all the devices were using are chock full of lights and LEDs so we need to cover all of that so we can see the glow as it's extremely dim we're done with the scope now so that can be turned off the screen and light of the frequency generator should be covered with something very opaque the light on the power supply I'm using to power the amplifier and the power indicator light on the amplifier itself also need to be covered then find and get rid of any other lights in the room I also set up some foam walls around the experiment to shield it from other stray lights as the hackerspace I work out of is chock-full of LEDs because well nerds love their LEDs set up your camera and you're ready to take the photo kill the lights and take as long of an exposure as your camera can or just wait a minute for your eyes to adjust and you should be able to see the glow the first time I did this I was using my Nikon d3200 and even with the 30 second exposure the glow was pretty dim but to be fair the lens I have for that camera is pretty cheap and slow but it did manage to capture the glow what is helpful is to have a remote shutter release and take even longer exposures of a minute or more to capture more light but once I had this working I just switched to my new far superior camera which is a nikon d750 and a much much better lens with this camera I could see the glow even after a six second exposure but I still took long exposures so that you could see the glass of the flask and it doesn't just look like a white dot on a black background my best shot was taken with a couple minute exposure so the glow was super obvious and the flask was nice and clear a quick note is why some of the other tutorials about this just really aren't great while they do contain a lot of decent information in many of the papers and those tutorials rather than using a single transducer like we used here they use a pair of them facing each other on either side of the flask the problem with this is that if there's any irregularities and how they're stuck on and if they aren't perfectly lined up with each other it's essentially impossible to trap a bubble and the whole setup is much much more sensitive to being bumped and the tuning whereas with my setup once the bubble is trapped even if the flask gets bumped a bit as I go to remove the light the bubble stays trapped and settles after a moment with one transducer you only need ten Hertz of resolution on your signal generator but with two you need one Hertz of resolution really it's an absolute pain and there's no real benefit so don't bother just use a single transducer unless you're some sort of masochist that likes watching your experiment fail a thousand times okay now that it's working we can finally talk about what's actually going on starting with the most popular theory the short version is that as the bubble compresses the small amount of gas inside the bubble gets very very hot at the moment of peak compression about seven to ten thousand degrees by most estimates this turns the tiny amount of gas inside the bubble into a hot plasma which emits a flash of light this is known as the thermal plasma theory of sonoluminescence some of the other now discounted theories include weird quantum fluctuations charge buildup on the inner and outer surfaces of the bubble and lots of other weird effects but the data just doesn't line up with those theories specifically the thermal plasma theory was up until recently the only one that could explain the spectrum of light that comes out of the bubble by most accounts the light is a nice smooth blackbody spectrum you'd expect from a tiny dot of hot plasma and most of the glow comes from a little bit of noble gas that's in the air naturally and that is what's been doing most of the glowing because of the extremely high temperatures some groups thought that you could even use this to generate nuclear fusion by subbing out the water for deuterated acetone but basically every study that tried to replicate that idea came up empty not only that but the professor that originally claimed fusion was eventually found guilty of fraud and messing with the data and was eventually stripped of his professorship and barred from getting federal funding but here's where it gets weird the hot plasma theory relies on the light coming out at exactly the moment of peak compression but now enter the newest contender the cold gas Theory basically the researchers behind this theory contend that if the light doesn't come out at exactly the moment of peak compression then it can't be hot plasma as you'd expect it to get brighter as the temperature rises which is what would happen is the bubble compresses instead they contended that the opposite happens first as the bubble expands the gas inside cools very rapidly they predict to about four degrees Kelvin or minus 269 degrees Celsius this freezes the gas suddenly but the gas molecules still have residual energy as they weren't frozen a fraction of a second ago they then posit that the residual kinetic energy gets stored by the electrons of the gas as the bubble begins to compress and the temperature rises past about room temperature the electrons released this stored energy as a flash of light and then as things compressed you eventually still get the hot plasma just no light emission personally I like both ideas and can't really say for sure one way or the other both make great stories and fit the data pretty well but to be able to figure it out we need more people to precisely time when the light occurs which is part of the reason I'm making this video I have neither the time or patience to do that sort of testing but I'm hoping this video will inspire the next generation of physicists to tackle this problem and finally figure it out to close out let's look at what happens when you mess with the liquid and use something other than pure water the literature claims that if we sell out the water entirely and use concentrated 96% sulfuric acid the glow is supposed to be 3200 times brighter but I could never get it to work no matter how long I left myself Urich 2d gas it just kept bubbling and never degassed enough to try it so for those of you who know how to handle this stuff safely it's something you could try but obviously exercise extreme caution in theory if you get it working the temperature at the moment of peak compression is much much higher than in water some estimates put it at around 75,000 degrees also I should mention that anything other than pure water will resonate at a slightly different frequency see so you need to retune everything to that end even just the temperature of the solution also changes the resonance so you basically need to retune the whole system every run to make sure it's all working properly and the colder your liquid is the brighter the glow is in theory another thing to try is dissolving salts in the water and seeing how that changes the bubbles glow the only one of these that I tried was sodium chloride but I don't think I had a concentrated enough solution to really see any effect one of the papers I linked in the description shows the glow gets a distinct orange from sodium emission so that's something that could be fun to try if you replicate this since the glowing bubble should release UV light a friend suggested that I try adding some fluorescent dye to see if it makes the surrounding water glow I just dipped a yellow highlighter into the solution and when I fired it up it did kind of seem like the area around the bubble was glowing slightly but again it was really hard to tell up until now we've only talked about single bubble sonoluminescence and normally putting in more power just pops the bubble and ruins the effect but if you keep adding more and more power you eventually get multi bubble sonoluminescence which is exactly what it sounds like you use a lot more ultrasound power and can make multiple bubbles glow though each bubble will be much dimmer than the single bubble we used here but also you risk exploding your flasks if you're not careful normally this is done with a ram type ultrasonic probe like we made in a previous video rather than strapping the transducer to the flask itself I've included a ton of papers and other resources in the description for those that want to learn more as I had to leave out a ton for the sake of time and my own sanity including using sonoluminescence for all kinds of cool chemistry and other liquids and variations there's a chance we may come back to this in the future but honestly the main reason I did this was so I could finally stop thinking about it as it's been knocking around in my brain for five years that and so there's finally a decent resource so other people can pick up where I left off and honestly as amazing as it is I'm glad to be done if nothing else I think this will make an awesome science fair project for those of you interested or maybe the center of your PhD dissertation if you're really interested but for me it's on to the next projects and I can't wait to get started and now I can add capture of star and a flask to my list of wizardry finally let's talk about the giveaway thanks again does circuit specialists I'm giving out three of these amazing devices to to the general audience and one to my patrons all you've got to do is go to the link you see on screen and sign up with your email by doing this you'll be signing up to circuit specialist mailing lists they have a huge selection of awesome electronics meters tools and more and I can't recommend them highly enough and remember if you use the coupon code thought Emporium you get 10% off the winners will be announced in the next video and I wish you all the best of luck for those of you who win and even for those of you who don't but feel like replicating this experiment when you get it working tweeted at me so I can see I'm excited to see how you tweak the experiment what other liquid you try and how your results differ from mine and again if you go to the link in the description you can get all the electronics you need to perform the experiment and then all you need to do is get the flask of your choice to complete the setup and that's where I'll end the video as always I need to say huge thank you to my many patrons channel members and supporters on cofee that gave me the freedom to bash my head against hard experiments like this even when they fail a hundred times so if you'd like to support the show and want to keep the flow of science videos coming consider kicking a buck or two my way if you enjoyed you know what to do subscribe ring that bell hit the like button and leave me a comment with what experiments you think I should cry next and if you want more science and want to see these projects long before they end up in videos be sure to follow me on my other social media platforms that's all for now and I'll see you next time

Channel: The Thought Emporium

Views: 1,727,047

Keywords: sonoluminescence, mantis shrimp, cavitation, glow, light, ultrasound, acoustic, acoustic levitation, plasma, pistol shrimp, electronics, LC circuit, resonance, frequency, physics, science, how to, tutorial, instructional, thisoldtony, electroboom, hantek, osciliscope, frequency generator, sine wave, sound, Circuitspecialists, Circuit Specialists

Id: puVxGnl_3y8

Length: 27min 11sec (1631 seconds)

Published: Thu Sep 05 2019

Reddit Comments

[u/jacktherer]

what if instead of a pipette and a flask they had a vacuum chamber and some gases?