The Action Lab - 2025-07-18
Why is there no splash in a vacuum? I try the experiment for myself to see if splashing disappears in a vacuum chamber. Published paper on this effect: effect:https://arxiv.org/pdf/physics/0501149 Where I found the video of the splashing drops by Sidney Nagel: https://www.quantamagazine.org/finding-beauty-and-truth-in-mundane-occurrences-20250509/
Thank you for solving a long time issue! I’m now going to start giving my kids a bath in a vacuum chamber. No more splashing and no more wet floors!! You’re the man!
If you keep the vacuum pump running once they're finished, they'll be desiccated. This will save the need for you to towel them down afterwards.
Another tip. When the police arrive say nothing until your solicitor is present. Just tell them you don't know what happened.
one final bath indeed.
😂 crazy
@KenFullman When the police arrive, just turn on the bathroom shaped vacuum chamber again.. problem solved.
@KenFullmanOr just dry them off with an IR laser.
could you then do this test in a pressure vessel and expect a larger splashing effect?
Yes, that would be a good one!
yes like over 5 atm or in different density gases like co2
yes, i would watch that too
Exactly what I came here to say!
Beat me to the same comment by an hour!
Wait a minute; the video is only an hour old! You commented as soon as he posted the video!
0:15 MINECRAFT SLIME BLOCK PLACE SOUND
How many hours of Minecraft would you need to recognize that sound from one sample?
@MikkoRantalainenat least 5
@MikkoRantalainen LMAO
And?
@MikkoRantalainenNot very many
I spent a few decades in high-vacuum, designing chambers, valves and feedthroughs. Your solutions to the problems of getting power and materials into the chamber are ingenious! On the other hand, I cringed at the flat-sided chamber. That looks to be a couple of square feet on a side, which would mean over two tons of force on each face! It obviously works, but I don't know the longevity of plexi when cycling at those forces.
Oh, to get drops into the chamber, use a micro-pipette with the nozzle placed in your access port. Also, be sure not to run your turntable motor for more than a few seconds at a time since it will overheat very quickly. The only cooling available is radiative and a little bit of conduction through the structure. If we ever had to put a motor inside a chamber, we needed to "can" it with a cooling jacket with cooling liquid circulated through it. Finally, I would guess that the transition from splash to no-splash happened during Knudsen flow, a regime that is the transition between viscous flow (like we are all sitting in now) and molecular flow, where you can treat gas molecules as ping-pong balls.
Very good video!
You are amazing being able to keep clear headed enough to do design work even after decades in high vacuum. The hypoxia alone would kill us mere mortals.🙂
@karlharvymarx2650 🤣🤣🤣😂😂😂
Yeah, I'm really good at holding my breath...
I wouldn't have thought about the cooling issue. Makes sense, I just don't think of myself as being surrounded by high pressure coolant all the time.
Fascinating. Thanks for sharing.
@karlharvymarx2650yeah, that must have been depressing....
What amazes me is not that liquids don't splash in a vacuum but that the fact has only just been discovered...
It has been discovered several years ago. I am not sure of the exact date but its at least 20 years ago, when this specific group discovered it. I believe there is another paper/group who discovered it even earlier.
Seriously, astronauts have been going into space for decades and movement of liquid in vacum has been well documented. This just seems like a grade school level science fair experiment at this point.
@eddiemason4316 you seem to confuse vaccum and zero-gravity
I mean, usually you don't want liquids in your vacuum.
What amazes me is how counterintuitive it seems to even very smart people. It feels like a lack of critical thinking being applied here- after all, what even would make the drop splatter? It is assumed, and that is the part where an open but critical mind shines.
All the momentum is at the floor, if momentum was allowed to play out it would just cover the surface according to it's surface tension. So clearly something else plays a part, and obviously anything moving through the air is going to interact with it. It would have been(and was) natural to me to hypothesize that the air is what was causing the splatter, so in a vacuum, there is no droplets.
It's so cool when people do an experiment that has an unexpected result that just leads to new questions. And you'd assume we know everything about something as mundane as a water drop, but physics has a way of surprising us.
is funny that we always neglect air resistence and it was literally why we got surprised by the vacuum interaction.
Completely agree. Having my mind blown is one of my favourite things, but it's hard to describe why something can be 'unexpectedly mind blowing' as opposed to 'expectedly mind blowing.' This is why science rules
@TheAluas Strangely enough, many scientists don't like their 'minds to be blown' at all. Especially when it comes to stuff that seem to break the laws of physics.
Some say it has something to do with an autism paradox. On one hand autistic people often feel attracted to science since doing research is usually very orderly, structured and predictable. But on the other hand many of them hate it when research results don't confirm their expectations and therefor tend to falsify results in order to 'not rock the boat'. A strange paradox that limits science from doing 'out of the box' research.
And lets be honest, isn't it a bit weird to blindly assume that certain things are impossible because a bunch of glorified monkeys said so? Not too long ago everyone assumed our planet was flat and that you'd fall off if you sailed too far. I'm not holding my breath on those laws of physics.
1:10 for a moment I really thought you were going to see if it was really true that it causes you to fall to the floor laughing
Spoiler, he did not.
🤣 I love when it’s kinda ambiguous based on context. I mean if you only hear the sentence before it does seem like that
👁
Science nerds have a completely different sense of humor. I, myself, love some good old science jokes.
Sry for the dealyed response. I was on the floor laughing.
I've been a mechanical engineer for over 25 years, having careers in process piping and food processing equipment, and I am today years old since I knew about the science behind splashes.
thank you for the wonderful science videos.
I'm an engineer with a minor specialty in fluid dynamics and I've never head about this before in my life! I would've never guessed but now that I've seen it happening it makes perfect sense.
I know that in hydraulics if you use two incompatible fluids of different densities in the same system you get issues that are essentially splashes. Cylinders will shudder and move inconsistently. The pump goes nuts. I once had to troubleshoot that very problem. A real head-scratcher until I found out somebody accidentally topped off the hydraulic reservoir with distilled water. It emulsified (splashed) under pressure and then separated in the atmospheric tank. With high-speed cylinders with quick exhaust valves feeding into a return pump at atmospheric pressure , and three hundred feet of 2 mm high-pressure hydraulic line it was a real mess.
See my comment which explains the simple physics of the splash. I am an engineer as well. It’s right in front of you!
Air pressure is additive when droplets have a vertical component (in the direction of gravity) because air pressure on the bottom side of a droplet disappears when it encounters a solid object. Simple physics people!
@CountPenta Air pressure is additive when droplets have a vertical component (in the direction of gravity) because air pressure on the bottom side of a droplet disappears when it encounters a solid object. Simple physics people!
Ok. Now we need to test a pressure washer in a vacuum.
And a vacuum cleaner in a decompression chamber
Also, at 5:41 you can see the top drop is flattened horizontally from the air resistance, but the bottom drop is perfectly spherical at low pressure. So neat!!
Oh yeah, great observation!
When ignoring air resistance, one can assume a perfectly spherical droplet.
That is so cool
Yeah I never would've guessed honestly that's why it splashed.
Love it.
Beat me to it!
I can imagine moviemakers using this effect in a movie. It is often fascinating to guess or figure out how certain physical movie special effects are done.
Wait, so air resistance is not negligible??
Never has been 👨🚀🔫👨🚀
😢 i thought my physics teacher was always correct
I always wanted to see the sperical cow in an infinte plain...
only for spherical cows!
Résistance is only négligible in high school 😂
Lets not tell the engineers
You are outstanding when it comes to,
selecting interesting physics,
telling how you intend to illustrate it,
visualizing it and finally explaining.
Your channel is definitely one of my favorites.
Greetings from Sweden
Exactly!
When I have watched that guy first time few years ago I thought he was weird... and I was right.
He is weird but in the right direction. Great mind!
Wow, your comment is almost like a haiku.
@maskedmarvyl4774GET OUT OF MY HEAD 😂
@maskedmarvyl4774 I thought the exact same thing!
@balboa9439 his early content was very homebrew-style. Really gave the vibe of a guy in his garage with a phone camera lol. But he's one of the best science channels on here now in my opinion.
This is why experimentation is important! I would've never intuited this in a hundred years, but once you see the experimental results, coming up with an explanation is a lot easier. Feels obvious in hindsight.
How about at a higher atmospheric pressure?
EXACTLY what I was thinking...
I was wondering if you could get the pressure high enough that the water drop would stay a drop. Like, if it couldn't over power the air and the air just forces it to act more like a bouncing ball.
ngl we share the same idea
@ImKovu the surface tension of water is enough to do just that without an increase of atmospheric pressure
slow mo guys actually captured this perfectly in one of their older videos
I love how you don't just describe the scientific concept, and other folk's video of the experiment, but you actually replicate it, in true scientific method fashion. Most of us couldn't do the replication ourselves, and you help us out by doing it for us!! Thanks!!!
0:20 no...splash, Captain!
Brilliant Mr smee 🏴☠️
An agile mind you have
Not a bloomin ripple
Now that's a reference!
😂🌚🌚
1:50 you could've sandwiched a bit of cloth under the magnet to wipe away the previous drop. But I think the turntable solution is way cooler.
Thank you for showing discussed effects right on the beginning, not like other channels after yapping for 25min
I love scientific discoveries about basic fundamental interactions! It isn't always the high-cost, complicated discoveries. There's still really basic things to be found
Idk what's more mind blowing: the lack of splashing or the fact that we only discovered this phenomenon 20 years ago.
20 years ago? Dude, that's a 2025 article, basically super recent. Can't be right, 20 years have gone by, WTF...
A 2005 article*
@CaliChemist_ITA We are living in the future 😎
Definitely the later to me. The instant I saw it, I already knew why it wasn’t splashin. But i have no bg in science and no tools so I don’t get to do neat experiments. I only get to ask what ifs and think about it in perpetuity🤷🏻♂
It’d be neat to see what it visually looks like to smack liquids in a vacuum. Especially if you use colored lights/liquid for better visuals.
That's absolutely amazing. I always say "any day you learn something is a great day" and this absolutely was a thing I did not know, and would not know except for your channel. Beautiful. 🖖😎
Splashtonishing!
Indeed
I’m 74 and always loved science and that’s why I reckon your up there with the best, in finding and demonstrating nature at work. Those who don’t appreciate your work simply lack imagination and the thinking process. Take care from an avid follower in Australia 🇦🇺
how were the dinosaurs back then
That was quite the surprise! So counter intuitive to one's thinking. Thank you for the demo.
Forget about the splashing phenomena (not really, it’s awesome) but for me, this video is about engineering and creativity to solve “problems” or issues that need to be dealt with to get results. You rock James!
The JWT design on Tshirt is genius. Love it.
Thank for answering question! I always wondered why the rain wouldn’t splash on the ground when there was no atmosphere!
I love how your solution to drying the surface off was a spinning mirror instead of sticking a rag or paper towel to the magnet you literally just used for the previous attempted solution.
Also, running mains voltage over exposed copper tape instead of just using a 12/24DC motor.
I would have never guessed that - Thanks for showing
Your presentations are getting so much better. Not just in your 'script' but also in your visuals and demonstrations.
before watching the full video, i am at 0:45 my hypothesis is that due to the water needing to push away air some of the air takes some of the water with it while being pushed away
Whatever his name-Helmholtz instabilities need another fluid that’s my hypothesis.
I think it’s surface tension
Ahh You were wrong. It was the droplets ability to spread out because no air was in the way. Spoiler warning.
i wonder what would happen if you dropped it onto a hydrophobic surface. and also a spherical surface
Once it got close enough to detect the hydrophobic surface, the drop would stop and reverse direction
the hydrophobic surface would cancel the drop on twitter
AND changing the gas from air to other vapor state of different types of liquids vs different types of liquid drops. Polar vs non-polar liquids / gases (with different viscosities). The experiments with bouncing oil drops on oil baths explicitly REQUIRE an atmosphere!
@Ancient_Yuletide_Carol wrong
Dropping liquids on hydrophobic surface in vacuum (and near vacuum to find transition point) would make an interesting video. And if the water stays flat on hydrophobic surface in vacuum, what would happen when you slowly increase the pressure again?
thats awesome bro. I wonder what role the surface tension of the water plays in containing the water drop as a single unit to regroup into that pancake. Keep up the great work mate.
One of your most surprising and amazing videos, yet so simple. Beautiful.
While you have everything already set up, you should try not just a single drop but more....or make a little container with liquid and drop small metal ball (with be easy with magnets)
So awesome, thanks for sharing!
Holy, didn't watch your channel for a while, the new vacuum chamber you've got now is GIGANTIC compared to the previous one!
1:17 I bet the air is shearing off fragments of the splat and then the elastic tension of the surface breaking gives it the extra energy to send it further
I have a PhD in Chemistry and a degree in science which included Math and Physics at Uni. I watch a lot of science videos on YouTube, and often can guess or understand a phenomenon. However, when I saw the title of this video, I just thought what? Surely liquids would splash in a vacuum? (Though ultimately liquids cannot exist in a vacuum). Just had to watch. Thank you for selecting and posting.
Yea, it not to often I see a science yputuber do a demo where I haven't know about the effect. But I've been working with high vacuum systems for 20 years and have never heard of this. Granted most of my experience with liquid in vacuum is when something is going horribly wrong so not really paying attention to invidual droplets.
Well that makes me feel smart 🤓🤓
I worked with piezoelectric dispensers for a few years while making immunoassays, and I thought it was pretty interesting that the picoliter droplets didn't splash - they made (near) perfectly round circles when depositing the proteins. If they splashed, we would have picked up a bunch of static around the drops upon analysis. So from the explanation given here, there might be a size limit when trapped air becomes a factor in creating splash, and we were operating under that limit. I always kind of thought the splash droplets were so small that they effectively became water vapor, or at least misty enough to get caught in air currents and not deposited.
And now I want that experiment.
The element Mercury is a liquid that would survive a vacuum. Change My Mind
@LawernceSimmonswouldnt it slowly vaporize?
Very interesting. I worked in both high pressure and low pressure environments but I never gave the question much thought...very thought provoking...it makes sense when you think about it.
It's amazing that the mechanisms behind something this mundane, have only been discovered 20 years ago. There's SOOOOOOOO much we have yet to learn. Thank you.
No, it's not been discovered 20 years ago. Most people who knew about it before then thought it was too basic to even call it a discovery. It's something so obvious when you're literally compressing a gas between two thing, there's bound to be more of a push up.
5:02 for those who needs simple answers
Thanks, it was a small curiosity, i just need the explanation.
Thank you for recreating and explaining this! I spent my undergrad in a chemistry/mass spec vacuum lab, and loved vacuum science.
I think stuff like this illustrates that our views and assumptions about how the world works are so strongly shaped by the conditions we live in that we don't even question certain phenomena. In this case, we haven't even questioned why or if simple momentum is strong enough to break the surface tension of a falling water droplet. It seems we just assumed it was because that's our every day experience
true
like the fact that it is the same affect that let a older car with a carburettor can drive and the force that make a big earoplane flies . Venturi , in the carb exactly Bernouli affect
Could you do dropping a drop onto a liquid surface? That normally splashes, it would be interesting to see what effect low pressure has on that too!
Or a small pebble
At 4:12 (and at 4:48) comes a second drop in the liquid surface of the first one. It doesn't splash.
@martinwest2538 If you go frame-by-frame around 4:12 (pause + comma or pediod on desktop browser on YouTube) you'll see that there's a small splash-like form. I would assume we would see some kind of splash if the drop was high enough. The depth of the target liquid might also affect the results.
That is really wild. Great video! I'm amazed at these little things we take for granted!
Are you one of those geniuses wondering what would happen at higher pressures? 😏
SPOILER ‼️
If liquids don’t splash in a vacuum because there’s no air to interact with the surface, then logically, increasing the air pressure should have the opposite effect. In a high-pressure environment, there are more air molecules packed into the same space. This creates greater resistance (or drag) against the moving liquid, which enhances the forces that cause splashing and break the liquid into droplets.
But here’s where it gets really interesting. At very high pressures, the air becomes dense enough to significantly affect the liquid’s shape and motion. When a droplet hits a surface, the thick cushion of pressurized air resists its spreading and collapse. This can cause the droplet to stay more intact or even bounce slightly, because the air is absorbing and redistributing the energy. It almost behaves like the droplet is hitting something springy, even though it’s just gas.
So yes, higher pressure not only increases splashiness, but can also stabilize or reshape the droplet depending on how extreme the pressure is.
P.S.: Reposting a bit of this from the other thread because science questions like this deserve a full answer 😂
I find it so weird that nobody has noticed a splash in a vacuum until now.
Edit: ok it was 2005,but still seems a bit late.
Similarly, a man invented a new kind of screw around the same time
ts is so tuff
I thought the same thing, however I think it's simply because high-speed cameras have been INCREDIBLY expensive only until the last decade or so. Even in 2005 a high-speed camera was about $100,000.
The biggest reason, imo, is that generally if you're going through the trouble of creating a vacuum you want a vacuum, liquids evaporate and poison the vacuum so are avoided at all costs. But that's high vacuum for physics based systems, chemists use rough vacuums all the time with liquid agents, but I suppose they aren't interested in the splash mechanics since they're doing chemistry not physics.
@SylviaRustyFae Details? Sources? Names? I'm curious!
This is intensely fascinating! This is mind boggling. I wonder what else acts the opposite one would expect in a vacuum…
@TheActionLab - 2025-07-18
Answering a few of your questions:
1. Why didn’t the alcohol boil in the vacuum? —because I was still above the vapor pressure of the alcohol at room temperature. Boiling point of IPA is around 6kPa. It did evaporate faster than at atmospheric pressure but the liquid hung around longer than you’d expect. That’s why I needed to have a mechanism to wipe off the drops.
2. Why not use water?—the original experiment was alcohol. So I wanted to match it. I used 99% isopropyl alcohol. I actually tried it with water but even in atmospheric pressure there is very little splashing that occurred. The surface tension of water is much higher so this suppresses the splash. The alcohol gives an explosive splash but the water barely splashes.
3. So increased pressure should give more splashing? —yes! Although I would assume there is a “saturation” point where it splashes as much as it can. But it’d be cool to do this in a pressure chamber and see.
@YoReid - 2025-07-18
That still counts as a vacuum? I would assume it being above vapor pressure would mean the amount of air is not negligible and so it wouldn't really fit the definition of a vacuum anymore
@gregkocher5352 - 2025-07-18
I suspect a drop in a pressurized box would not only splash more but travel a shorter distance. A bit more air would provide more resistance to liquid moving.
@Commenter-5519 - 2025-07-18
@YoReid I wonder if you could use some liquid like gallistan with a negligible vapour pressure. (Like a few atoms/cubic kilometer, I think I read somewhere.)
@Quardanter - 2025-07-18
Fqct: this is generated by AI, specifocally, ChatGPT
@KenFullman - 2025-07-18
I notice you used alcohol. Alcohol has very little surface tension. I don't understand why you didn't try the same experiment with water. It would have been interesting to see how much difference that made.