A big thank you to Benjamin Apffel, Filip Novkoski, Antonin Eddi and Emmanuel Fort for giving me their experimental footage. Hope you all enjoyed the video!

Ohhh, so _that's_ why Australian boats don't fall off the Earth.

Finally. I've always wanted to levitate some silicone oil but was never quite sure how to achieve it.

"Inverted buoyancy" is definitely a high school project winner. Looks so simple, yet so unreal.

This upside down buoyancy is the most incredibly interesting thing I have seen in a long time!

"It makes no sense until you think about it for a bit. And then it makes sense again. And then you think about it a bit more, then it stops making sense. And then you think about it even more, and then it makes sense again" This applies to a lot of things in life and life in general lol

"Dear, why is honey and 120 Hz Vibration generator on the shopping list?"

Wow, I've seen lots of mind-bending science youtube videos but a boat floating upside down on the bottom of a levitating lake of silicone oil might take the cake. Great video!

"Here is my vibration generator" Okay, Steve.

9:50 but in the end, the making sense of the problem averages out until there is a stable making of sense.

8:40 You originally said "body of water", didn't you. I almost didn't notice the overdub, that was really well done.

That visual aid at 8:58 was perfect, really connected the concept of 'accelerating downwards = negative g's = smoother surface' to my intuitive understanding of how I imagine things would work

1:51 Ah! I see the scientist is a man of culture as well.

1:40 - "A group of scientists were working on the problem..." It amazes me that someone was sitting around and one day thought, "The fact that honey doesn't levitate in the middle of a jar is a real problem that needs solving."

Scientist: Are you stable? Viscous liquid: Well yes, but actually no

Amazing! This reminds me of something else... This stabilising effect of a vibration to a vertical structure can also be illustrated in five storey pagodas common in Japan. The topmost spire or sorin consists of a shaft on which floating rings are attached near its base which springs from the roof. This shaft runs along the entire core of the tower and is free floating. On an event of an earthquake, the rings jiggle vigorously, stabilizing the shaft. This , together with the manner of construction of the tower, ie wood joinery, are believed to contribute to the overall seismic resilience of the structure. These pagodas are vaunted to have survived severe earthquakes.

This was a really good video, this is a marvelous effect I never knew existed and it goes completely against my intuition. The video explained everything very well and in a simplistic manner, and I found it genuinely entertaining to watch. Thank you!

The "Inverted Buoyancy" part of this should probably be mentioned in the title. I would watch a whole video only about that!

I love the little boat the put in there. I'm just imagining an excerpt from their paper on this effect. "Compared to a liquid at rest, the analogue navel vessel (ANV) displaces..."

It actually looked to me like the inverted boat was covered in a film of oil. In fact, some drops of oil could be seen dripping off the tip of the mast. Could it be that surface tension was playing a role in keeping the inverted boat in position?

Dude, great work in the edit, that voice over of 'Liquid' when you say 'water' is seamless! Even got the tamber on point. Well done!

8:40 That was a flawless audio correction. I'm so impressed. The only way to tell was the missed synced lips, but even then I couldn't believe it. Awesome. The floaty liquid is cool too.

Saw the title and thumbnail but passed on the video cause I never get any good info out of these kind and it's a waste of time, but then as I scrolled I saw it was Mould and raced back to watch it cause I can trust the quality in your work

Excellent parlor trick of science. Reminds me of early electrical and magnetic display pieces presented to explain what is really happening! Love your videos

Enjoyed the video, thank you. One matter which stood out to me was you 'free from gravity' demonstration 0n the table. The effect is exactly how a semi-trailer works when being pulled (driving/turning forward) and being pushed (backing the trailer into a dock/around a corner).

Inverted boyancy... "when you think about it, it makes sense" NOPE HE'S A WITCH

I wanna say thank you man and please keep making these videos. I just now found this channel and i LOVE the fact that i get to listen and learn SO DAMN MUCH. Like..... yes. The world needs this lol

Loved your pendulum explanation with the torque and perpendicular forces, actually quite intuitive!

Steve "I'll leave a link to it in the description" Mould 😂

10:07 "Submerged seems a bit wierd in this context", how about upmerged?

You do an amazing job about a explaining things by introducing base concepts that can be understood and then building on those explain the more complicated phenomena.

“If you want to find the secrets of the universe, think in terms of energy, frequency and vibration.” Nikola Tesla anytime you want to "defy" physics try vibrating it really hard, it might just work

9:00 When you're talking about forces at play, I think you're also forgetting atmospheric pressure. The air trapped beneath the silicone is also oscillating up and down at the same rate trapping the liquid additionally. This also would be part of the effect for the upside down boat.

Why have I not seen this channel before? I need to binge these videos next weekend. Fascinating content!

My mind has been blown by your last few videos! Keep it up!

10:05 "Immersed" or "semi-immersed" might be a suitable alternative for the situation. It evades the up-down connotation of "sub-".

1:03 holding jar, hand and camera upside down. Genius

Thanks for this great video. I like your intuitive approach to explain the stability of the vibrating inverted pendulum. You can even explain the stability of the vibrating inverted pendulum without mentioning forces and vectors (which is already quite advanced for children in elementary school) When pulling the rod, it acts as a hanging pendulum. When pushing the rod, it behaves like an inverted pendulum. The time it takes from a perturbed pendulum to move towards it's equilibrium point is much shorter than the time it takes for an inverted pendulum to move from it's equilibrium position towards a small displaced position. It's not as accurate, since it's a little more complicated than that, but it's even more intuitive.

Submerged upside down - could it be “supermerged”?

I LOVE this video. A few weeks ago I read the article that you referenced at the beginning, and I couldn't quite wrap my head around it. Your explanation and the scientists' video footage really make this whole concept much clearer. Thanks Steve!!!

10:07 the word you’re looking for is “supermerged.” i may have made it up but it definitely works here

Very cool video! Also interesting is seeing the liquid drip from that upside down boat, sort of escaping the tension through that pointy bit on the top!

I love this awesome explanation! Taking "magic" and making it seem obvious and intuitive! Thank you for this!

Awesome! *thinking of applications* I know - I'll hide my valuables in an opaque honey jar underneath a floating layer of honey! No one will think to look under the violently shaking honey jar! Now I just need to devise a bottom hatch that can open and close while the jar is shaking so that I can store and retrieve things without them getting sticky...

11:00 That there is youtuber speak for "I'm not one of the six people on the planet who understands this phenomenon well enough to explain it so let's not"

I just discovered your channel and I’m really impressed by the production quality, especially given this channel isn’t even about cameras and stuff like that. 60fps is cool, ur using an “edge light” and a fast aperture lens, like daaaam bro

This is especially fascinating to me for a very different reason, during my astronomy major the most interesting question I ever got was to model a harmonic oscillator of a displaced piston compressing an ideal gas, as a way to think about variable stars. And now here it is in the real!

I came here with one question: "What is silicone oil?" I leave with an unanswered question and a new one: _"What the [redacted]?"_

8:38 I thought my eyes were temporarily filming at a slower frame rate 😛

Awesome explanation, 3rd year physics undergrad here and always love watching your videos. Don’t suppose you’d do one on complex networks? (My dissertations on it haha)

Sir your videos inspire us to learn more about the world around us and question the curious phenomenon around us for those of us whose parents didn't went to university you inspired us to take action by these different content thank you

"To qualify to enter this competition you must be resident in the United Kingdom and aged over 18 years." *Sad Czech noises.*

8:40 ventriloquism! I love your videos! Also their fixes :D

This is the most fascinating think I've finally gone back into my Watch Later playlist and watched.

The last part where the boats seem to float up-side down really looks like a nice segway to gravitational fields. I look forward to your videos!

Another great video! I think the fact that this material has friction with the sides of the container the reason why the gravity correlation works in this explanation. I don't think the explanation holds in a frictionless environment, nothing to give a counteracting force for the "flattening" and it is what is allowing the drag on the upward movement.

I think it's awesome when scientists do things like make their buoyancy test items look like tiny boats. Makes you think they're enjoying their work 👍

I went into this video certain I would never understand what was happening but interested in seeing the cool visuals, but the explanation about vibrating pendulums made it so clear I felt my brain grow.

It's been a very long time since i've seen such an interesting video... Thank you.

I saw that levitating liquid and inverted bouyancy video but wasn't able to wrap my head around it,you made it pretty clear. Though I do not understand the whole process but the explanation you provided made intuitive sense. Great work.👍

5:10 it's not what you think mom! I can explain this is an upside down pendulum

Great video and something I've never seen before. Truly amazing content.

You are fantastic at explaining things and this is crazy stuff god bless Steve Mould

10:04 I think the word you're grasping for is "supermerged"

I hate silo cons. They don’t install the proper safety systems for grain storage.

I have a comparison that may help with the part about the inverted pendulum: Just as a wheel (not the bike frame's speed but the rotating wheel itself) stabilizes better at higher rotational speed due to the gyroscopic effect, 1D vibratory motion (up-down oscillation) acts the same way, stabilizing an inverted pendulum under the effect of gravity. It seems to me the commonly observed gyroscopic effect has the same underlying cause as the inverted pendulum's interesting stabilization. My reasoning is that a quickly-rotating bike wheel operates the same way as a vertically oscillating pendulum in that if you take a single point on a rotating wheel at a certain time, say the topmost point, and then let time pass, the point will proceed to the bottommost point and come back up, just like an oscillating inverted pendulum. Using the logic in your video about each components' vertical and horizontal differences (in acceleration) between the upstroke and downstroke of the pendulum (and in my case, a point on a wheel), your logic should also apply to forces perpendicular to a spinning wheel. That is why I feel that wheels are stable at fast rpm (i.e. keeping the wheel 'vertical' and not falling to the ground when the wheel spins quickly). Note: The rotating wheel shouldn't need to have frictional contact with, nor be moving with respect to, the ground - i.e. the wheel doesn't have to touch the ground. Look up 'rotating wingnut in space'.

excellent pendulum explanation on the table

4:20 I want this as an XXL version so that I could dive in it until I dived through the first one and jump into the second one 😊 It reminded me of a part in the movie "A world beyond", when they swam in a levitating water bubble. 10:28 How would it feel to just hold out the head (like the upside down boat) and still don't falling down. 😅

The inverted boat broke my brain. :(

I can not believe you just explained that Pirates of the Caribbean scene where they flip the boat

Very good presentation. Some vloggers think you need background music (in the foreground) or elevated playback speed to demonstrate the laws of physics. These videos of yours are a delight. Thank you!

6:32 I did not understand why this is at first: while the pivot point is pushing up, the rod goes from close to vertical to far from vertical, and while the pivot pulls down, the rod goes from far away from vertical to close to vertical again, so it seems to average out and the forces cancel. It turns out that I was confused by the model with the table where friction played a role as well. The force that pushes the rod away from vertical position is caused by the acceleration (not velocity) of the pivot point upwards, so it occurs mostly when the pivot is at the lowest position, so when the rod is closest to the vertical position, which is exactly what you said :)

So, effectively, "How to film the upside-down boat scene from Pirates of the Caribbean."

What a great analogy again! Thank you for the video!

Astonishing ! If it weren’t your video and explanations I’d be suspicious. Great vid as usual ! 🙏🏻

"If you think about it some more..." and some more and some more.... This is why we have some very indecisive people! Actually, on second thought, maybe it's not.... ...Or IS it?

I think where is a typo in the thumbnail 😅

I now want my desktop background to be a shot of the two boats floating on the liquid.

Your explanations are incredible. Thank you!

I love your philosophy of finding an intuitive explanation. Knowing how something works makes it easier to do the math, but knowing the math really doesn't do much to help you understand what's going on. I'm a little surprised they had you write a question and you didn't do "What is the most interesting thing to pour out of a beaker?" ;)

I can't wait to create precarious equilibrium with honey every time I use it now!

Wow. That was a great video Steve Mould

This just blew my mind when it clicked in my head. That’s just... i loved this

9:46 Are serious mr Mould? 😂 Reverse-buoyancy?! 2020 cannot ever surprise me, but turns out you still can! 🤣

10:05 Supermerged?

My interest stems from the moment you inject air at the interface of the liquid medium and the bottom of the vibrating vessel, you are effectively adding a gaseous spring, or the electrical equivalent of a capacitor, hence the mechanical equivalent of a damper, between the solid vibrating bottom of the vessel and the liquid medium you need to coerce into a vertical oscillatory motion (vertical as in parallel to the gravity acceleration vector). Because liquids are nearly incompressible, and can't easily cavitate at such low frequencies (inertial dynamic forces are too low) then coercing the body of liquid to vibrate with the vessel is intuitively obvious when st the beginning of the experiment, the solid bottom of the vibrating vessel and the denser body of liquid are in full contact. It's mechanically solid linkage between the two. So when you inject air between them, that link becomes a spring. It's like miatching impedance matching, isn't it? The equivalent capacitive reactance of the air has to do with its density, specific weight, and viscosity (environmental coefficients exist, so vessel pressure and temperature would affect that "springiness"). I believe that's why there is instability on both top and bottom of the levitating liquid; there's a time constant because of the air not being solid and this nonlinear, just as in an electrical equivalent circuit (low-pass filter, or R-C). I'm guessing that chaotic oscillatory "noise" we only see once the air is introduced, could be attenuated by better matching the impedance (electrocal equivalent of AC Coupling) by using a denser gas (a bigger capacitor) because your oscillating frequency is pretty low and your liquid is pretty heavy, therefore its inertia calls for a stronger coupling. Impedance matching like the fluid they put on your skin to better couple the ultrasonic frequency from the probe elements to your body. Is this insanity or is this a positive contribution to refine the understanding of the second-order dynamics we can observe from this apparatus? By the way, maybe this helps: In terms of density, the upside down boat is no different than the air layer underneath the body of levitated liquid - the air *must* float underneath the liquid just as the boat does. Lastly, before the bonus question, what happens if you inject silicon oil at the bottom? Does it just float back to join the silicon oil on the top? I don't think so, because it's like the boat. It's has to float on the surface even if upside down. Right? In a weird way, the underside of the levitated liquid is a inverse buoyancy universe. Not exactly a diode bit :) BONUS QUESTION : The question is, if you had a heavy load to the low-pass filter, you would normally see attenuation; But we see chaotic noise, not standing waves of surface perturbations. What is causing that mechanically chaotic noise in a closed physical system? Scroll for a theory... Though there's only one oscillating driver at only one single frequency, and to boot, it's presumably a sinusoidal wave, hence no harmonic content, but even if it were triangular the harmonics are a multiply of the fundamental frequency (120Hz) so they don't interfere and cause chaos. But I think the topside of the levitated liquid interacting with a less dense liquid is like an inductive load and the levitated liquid is the equivalent of a transmission line. Of you don't match impedances throughout the system, you will get reflections of unabsorbed energy (electrically bad or no termination so your signal rings) and those reflections are chaotic because of many factors like the propagation time of sound through the differing fluids, etc. If you ever read this, please correct me. I could really use a prize: Give me 5 minutes in your office waste bin. Thank you so much for your amazing and inspiring videos!!

Normal boats: merged Steve's friends' boat: merged

I was just watching a video yesterday from Cody’s Lab about floating a liquid on a gas (gallium on xenon I think). Weird timing.

8:40 Your voice says liquid, your mouth says water. Noice dub.

Thank you Steve, I'm guessing this is the final key to my perpetual motion machine.

8:58 "Not again!" Brilliant explanation.

05:08 I will not ask what else you use that thing for...

"Vibration generator Ahh, the scientific way of saying a vibrator

This explains a lot of things for me! Thank you!♥️👍🌟

Man, you're so good at communicating science.

5:53 [Matt Parker wants to know your location]

Oil? Oh boy, a certain military is gonna invade your channel

Woaaahhh!! that was amazing!! Thanks a lot Im working with acoustically levitated droplets of water, not the same or even a similar system, but also cool

Brilliantly explained. It's good to understand somethng intuitively, even if you have to do some non-intuitive work to get there.

od di just saw another video about this and the vid wasn't even new. it had a little boat floating upside down :)