"There are no magical forces sucking the balls" - Physics Videos by Eugene Khutoryansky

I’m genuinely glad that I’ve been a subscriber for quite a while now. I feel grateful towards you for making physics and mathematics my greatest goal and the center of my life, as I thank you for your constancy and dedication. We all appreciate you a lot around here. Always on point; keep it up!

The content on this channel is always excellent but what I love the most is the music and the voice 😂

This is how osmosis really works. I remember teachers mentioning a mysterious sucking force. Thanks for elucidating !

As noted in the commentary, there are no attractive forces between the particles in this simulation. This means that you are simulating two ideal gases (well, if we ignore the particles' volume). In such a case, the osmotic pressure is equal to the partial pressure of the cubes, while the partial pressure of the spheres will converge to being equal on both sides of the barrier. The simulation is not representative for osmosis in liquids. For liquids, there IS an attractive force between particles, and this is essential for explaining the high osmotic pressures in liquids. For instance, the osmotic pressure between sea water and fresh water is an amazing 24 atmospheres, although the difference in salt concentration is only 3.5%.

This helped my intuition a ton. So hypothetically if the membrane only let the squares through, we'd see the same thing but to the other side. Amazing.

I imagine most sorts of semi-permeable membrane can be abstracted to this kind of visualization? The purpose is to show that a shape-specific filter has that result whether they are simulated shapes or biology, chemistry, and physics doing their things, correct?

Such a fantastic channel, I cannot even explain how glad I am to have found this place, thousand thanks!

You never cease to amaze me! Amazing work as usual.

"This is the beauty of physics" - You just described your channel in a nutshell!

These particles sure have a broad taste in music!

Again, a MARVELOUS video! Thank you very much for your work!

Great demo! Another interesting case I can imagine is where there are some attractive interactions between the cubes(so it becomes a liquid) , but keeping only the same hard repulsion with the spheres. You can then demo some things like colligative properties, and also show that the 'vapor' of spheres above the liquid has equal concentration on left and right, at heights where there are few cubes. I've always wondered if there is a clean and intuitive way to visualize chemical potential, and perhaps this approach could help.

Thank you so much. You have the best intuition on physics, classical or otherwise.

So happy you are back!! ❤️ always supporting this channel since forever ago!!

This is indeed the beauty of physics. Extremely simple laws, profound consequences beyond measure.

Hey, I just wanna say: Your videos are amazing. They have incredibly insightful and intuitive demonstrations of otherwise hard-to-understand concepts. I get the feeling they're primarily intended for use in schools. But honestly, I enjoy them for their own sake. Keep it up; you're doing great work.

Oh god, so awesome channel. Thank you for your work.

Commendable job in visualizing this,thanks .

I used to watch your videos back in 2016 and your animation is awesome glad i found you on youtube still making breathtaking animations...That quantum Mechanics video was magnificent

I like the heavy metal backing track! The explanation is also very clear, thank you!

Yay! My fav youtuber uploaded!! Brilliant video and explanation, as always :)

I didnt expect that cannonball motion ricochet at 2:07

Fantastic as always Eugene!

Great visualisation of how osmosis works, and what is the difference between osmosis and diffusion. Thanks!

I feel those squares desperation, in struggling to get through the barrier

High quality delivery from Eugene as always. Keep it up!

Nice simulation I never knew osmosis on a molecular level. You have great taste in music ,listened to quite a few classical pieces while watching your previous videos.

Thanks for this video 🙏. It's one of the best in your playlists. I think I finally understood osmotic pressure. Please correct me if I'm wrong. So, initially we have water(spheres) on both sides and the pressure on both sides of the wall is equal. Suppose, we add NaCl salt and the ions get hydrated immediately and represent the cubes. The cubes owing to their larger size, restrict movement of spheres and even block them from effectively colliding with the barrier. This can be thought of as decrease in the pressure on that side. So, now the other side spheres will cross the barrier more frequently until pressures are balanced again. So, there are more net molecules on the salt side and denotes the increase in height. This decrease in pressure on the salt side is called osmotic pressure and proportional to the concentration of salt added.

Great video! Thanks so much for making these!!

Awesome work as always

Isn't it fascinating? You look at a simple household phenomena, and deep down it's a bunch of particles bouncing around, just so many of them that it looks like e.g. coffee going up a paper filter.

You're on the right track with this whole background music thing. Hopefully very soon, you'll decide to drop the whole thing. Believe me, your voice is mesmerizing, music here is unneeded.

This is one of my favorite topics. Very very well done.

Great as always.

Wonderful and very instructive as all of your videos! We must be careful with "entropy" here. If you consider a time-series of consecutive, fully described microstates for which you know everything you cannot define entropy. Entropy can only be defined if you set only marcoscopic quantities and ask in how many microscopic ways they can be achieved. What is meant here is that initially we have a microstate that is part of the low entropy "all particles in one side" set and we end up with a microsate that is part of the high entropy "particles equally spread on both sides" set. This happens because the initial velocities were randomized by the collision (no-gravity-simulation). Newtonian mechanics says that if we play the video backwards we will have a thermodynamics defying system which lowers its entropy. I only do not know how random is the motion of the diaphragm.

Thanks so much for sharing! BTW, I love your voice! 😊

narrator : the liquid on the right will continue to rise... BGM : *proceeds to literally destroy the guitar*

The blistering guitars in the background were a nice touch

Oh my God yes! I tutor chemistry and this is so helpful. Thank you!

This is a great visualization! but I'm curious if the squares would reach the same height as the spheres with a non-permeable membrane. I noticed that the squares could transfer rotational energy to each other and the spheres couldn't.

This is amazing! Thanks for making it!!

So squares block balls from escaping the square side of the barrier. Equilibrium is reached with more objects on the square side of the barrier.

Your clips are wonderful art! I am looking forward for Navier-Stokes equations to be visualised ;-) Why not, it worked with Maxwell as well?

How does an increase in pressure cause a displacement of molecules with equal densities? Why did the squares rise?

I really like these models, super facinating representations

I've been subbed too this channel for years and love it

I never thought of it this way, but could it be explained as simply as the cubes block the path to the barrier, so the balls on the left have a greater opportunity to pass through than than the balls on the right? Equilibrium is reached when the right side has enough "extra" balls in it that the occurrence of barrier interaction is equal on both sides? This is very enlightening! Thanks for the great videos!

Your simulation is very interesting to watch - brought me to the question, if the driving 'force' behind real Osmosis could be a pure filter effect? I'm not sure if this is your conclusion or very far from it. Just from what I saw in the sim, I think it's behaviour is all down to the barrier in the middle, which allows balls to pass from the left to the right side more easily than from right to left. The mid barrier could be seen as a filter with directional permeability, maybe like a coffee filter. For example, imagine a coffee filter installed in an Aquarium, where on the left side is pure water, while on the right we have 'coffee powdered water'. Now in the simulation the squares ('coffee particles') on the right partly block/clog the filter towards the left, so balls (water molecules) which happen to enter the right area have a higher tendency to stay there, than to return back - a bit like a sponge-effect, but without the adhesive forces. The reason why not (almost) all balls end up on the right, is that the right-to-left permeability ("leakage") effectively increases with more balls on the right, due to rising pressure (= particle-particle/-wall collisions per time unit) in this area, just like described in the video. With the filter's/barrier's permeability moving from directional towards unidirectional, the amount of particles on the right grows slower and slower - until a near-equilibrium state is reached.

Awesome demo. Thanks!

Another great video. I love it. 👍🏻

Отличные видео как всегда) где они были, когда я учил физику в школе?

Nice video! Also, good to consider that in equilibrium, at the side with solute, decrease of stability of solvent due to increase of pressure as osmotic pressure is compensated and balanced by increase of stability of solvent due to entropic effects (ideal behaviour) beside possibly solvent-solute interactions giving rise to non-ideal behaviour.

Great video, truly visually superb!

So glad I came across your video. Many thanks.🌹🌹

It would have been really cool if you let the simulation at 05:05 run to equilibrium, and then beyond that (maybe sped up). Just to see how it plays out. Especially to see how far beyond equilibrium the system oscillates.

On my first pass, i didn't see much of a justification for how this happens. I'll watch it again... Alright. it's easy to miss this, you mention that the influence of the squares is important, but you don't really explain why except in empirical terms: it happens, here's it happening. The balls can pass, but not the squares. The explanation would probably involve something like... The balls, being able to pass through, are able to exert a pressure through the membrane, while the squares are not. The effect of the squares is not the same as it would be had they been balls, because for a square to oppose the balls entering the right side, the squares must force each ball back through the membrane, while when there are only balls on both sides, a ball on the right side only has to pass through the membrane, NOT just force a different ball through. Therefore it is much more likely that, when there are balls on both sides of the membrane, that the balls on one side can resist an imbalancing flow of balls; and it is less likely that, when there are squares on one side of the membrane, that the density of particles would remain similar, because for this to occur, the presence of the squares would have to have an equivalent likelihood of decreasing the number of balls present in the right side as would an equivalent number of balls, which is not true because the barrier prevents the squares from performing one of the two ways a ball could achieve this: by passing through.

Brilliant video!!!

I love your videos. Thanks for always teaching me something new

Thank you for such a great video.

Your channel is the prime example of an extremely gifted educator doing excellent work on visuals!

Awesome, as always

I think it helps to imagine the diffusion scenario with the cubes-- left side has more pressure obviously. Add a few balls at a time. Now we see this increases the pressure of both sides, reducing the ratio of the two pressures. Dilute it enough with balls and they basically have the same pressure. I guess the paradox that people may be confused by is that the transition rate is not proportional to pressure. The transition rate of each individual particle is proportional to its partial pressure, times some coefficient determining the penetrability of the barrier, e.g. a partial diffusion timescale. Each particle type has its own diffusion timescale-- it may be infinity, as in the case here with the cubes.

This is a very accessible way of teaching it. You can probably append even more intuition to this without really having to get into the weeds with statistics. This is already useful as-is in a classroom where an instructor can provide an extra bit of explanation, but it would probably benefit this video as a supplement if there was a visual aid for what's happening at the level of the single particle: What I imagine is that every time a particle interacts with the barrier, there's a chance that it's either a ball or a square. Because squares can't pass through the barrier, then even though there might be just as many particles interacting with the barrier on both sides, the side with the squares won't send as many particles across the barrier, resulting in the side with the squares gaining more particles from the other side. I believe this would be another fairly intuitive addition to point out while still maintaining its accessibility to people less versed in higher math.

Great dedication...❤️👍

really really good demonstration

Outstanding demonstration of process of 'Osmosis'. Hats off to your efforts, which make the concepts crystal-clear👏🏻👏🏻👏🏻👏🏻👍🏻👍🏻👍🏻👍🏻

Hi! Thank you so much for such genuine information! Kindly upload more! Thank you so much.

They just that kind of charm to this kind of videos randomly appearing

Great video, as always 😇

You and your channel one of the most incredible places to visualize and learn physics. Specially understand it. YOU ARE GREAT

Great work 🙏

Did the KZfaq Gods randomly recommend this video to anyone else? Stayed for the whole video.

Thanks for the video!

Amazing! Completely kinetic!

Nifty as always !

Much needed for the future as a starting point

Excellent video.

Very well explained and visualized. Thank You

You can explain most of Osmosis more easily by looking at a container pressurized with Helium gas. The container is able to hold any gas except Helium which slowly leaks out of any container. As the Helium leaks out other gases are not able to leak into the container and over time a perfect vacuum will form. Looking at this example allows you to use only one gas and the vacuum as the two liquids with the vacuum being a non-participant. This exact situation was also a full days' mystery when my container developed an excellent vacuum all by itself over a weekend. Turns out this is one of the steps to create really deep vacuums (Roughing, TMP, Helium-Vacuum washing, Helium-Thermal pumping).

Thanks so much, this is amazing

I love the animations and always want more .

Fascinating and a great learning tool

Can we safely assume that the increase in the number of spheres on the right-hand side is caused by the cubes hindering the reverse diffusion of those spheres back to the left? I can imagine that moving from left to right is easier (fueled by diffusion) for the spheres than returning due to blockage of the membrane by the cubes resulting in an increased number of particles on the right.

I used to watch this years back no way it popped back on my recommended

Wow thanks I finally totally get osmosis thanks to this illustration, seriously thank you so much!

Beautiful demonstration. I am retired now, but have fought a long and ultimately unsuccessful campaign to have the word 'osmosis' removed from scientific writing. Students often struggle to understand 'osmosis' and end up seeing it as a strange phenomenon. As your video shows with wonderful clarity.....there is no process of 'osmosis' , there is only diffusion down a concentration gradient. The difference is that it is the solvent (water) and not the solute that diffuses. Or....more correctly, water can diffuse more rapidly, which leads us onto things like reflection coefficients. Wonderful video!

Awesome video.. loved it.

this is wonderful

This is beauty of the Physics. I love it!!

I don't understand how this video could have even 1 dislike wonderful explanation. And greatly edited video cx

Great job! 👍 Cleared all my doubts 😊

Great video

Another banger. Keep it up. Today I learned how osmosis works. Didn't even consider it before.

I must be slipping in my old age. I opened this last night meaning to watch it and fell asleep before I could. So I just went to watch it today, with the tab still opened, and thought the picture on the screen was some sort of novel Tetris game. Either that or constant stress has just broken my brain. I hear it does that.

One word, beautiful. carry on my friend

Pretty wicked! Thank you, wild!

Excellent content...

It was amazing to review concepts from high school times! Thanks a lot!

If I'm understanding this correctly, the reason the particles tend to gather on the side with the material that cannot pass through the barrier, is because their very presence on that side of the barrier sort of interacts with the nature of the barrier itself. Effectively making it better at sending the round particles through on side, and harder for them to come back.. due to the cube particles blocking them. The cube particles pretty freely let all other particles flow between them, but when they're up against the barrier their presence effectively adds extra pressure required to go back consistently. These interactions naturally create an equilibrium state that is counterintuitively asymmetrical.