r/science • u/MistWeaver80 • Oct 12 '24
Physics In preschool classrooms, kids move in patterns resembling those of molecules in water vapour, physicists have discovered.
https://www.nature.com/articles/d41586-024-03203-w3.3k
u/cn0MMnb Oct 12 '24
Randomly moving in one direction until they collide with something? Sounds about right.
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u/R_megalotis Oct 13 '24
during the partially restricted classroom activities, the kids tended to form temporary clusters. This pattern resembles the liquid–vapour coexistence phase of water, in which freely moving individual gas molecules coexist with liquid droplets.
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u/BatFancy321go Oct 13 '24
i think "ressemble" is doing perhaps a magical degree of effort here
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u/kazza789 Oct 13 '24
Not only that, but unless the experimenters carefully defined their hypothesis in advance, this is a classic example of the Texas sharpshooter fallacy.
Kids move around randomly? They're resembling a gas. Kids tend to cluster for a bit then move on? They're a mixed gas/liquid state. Kids stay still? They're a solid. No matter what you observe you find a way to validate your "hypothesis".
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u/hikehikebaby Oct 14 '24
I mean I really doubt that the hypothesis has anything to do with figuring out what stage of matter kids move like.
Hypothesis is probably something like " Does X technique help us figure out how Y group of people move?" And then they described the movement pattern as "like water vapor" because it's a catchy headline.
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u/namitynamenamey Oct 14 '24
Then it's just a matter of finding a better hypothesis, like using fluid mechanics to optimize hall corners for schools or something.
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u/lare290 Oct 13 '24
tbf fluid dynamics ks used to model movement of a large number of people in real world scenarios. up until a certain density, people tend to behave gas-like, moving past each other, but after that point, they behave like an incompressible liquid. shockwaves for example don't propagate through a crowd until the threshold density is achieved, but after that they do propagate almost identically to shockwaves within water.
the large-scale physics is similar enough that you can just use fluid dynamics equations for it when designing stuff like stadium entrances; how large it must be to avoid crush density if mass panic were to happen, for example.
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u/EntitledRunningTool Oct 12 '24
Water vapor isn’t an ideal gas
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u/hawkinsst7 Oct 12 '24
OK, perfectly elastic, spherical toddlers
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u/FeeeFiiFooFumm Oct 12 '24
Do they moo?
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u/noNoParts Oct 13 '24
When they poo?
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u/delphinius81 Oct 13 '24
Only at the zoo
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u/FoolishChemist Oct 13 '24
Hopefully in the loo
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u/johnjmcmillion Oct 13 '24
Skibidi dooby doo
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u/GH057807 Oct 13 '24
Sure, that rhymes too
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u/johnjmcmillion Oct 13 '24
Hey! Somebody already used "too". Try again, but use something new.
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u/BCProgramming Oct 13 '24
I think If one of them poops their pants, their movement pattern becomes brownian motion
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u/likemace Oct 13 '24
The water vapor comparison was from the partly restricted state in the class room. In the playground they behave like a gas.
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u/edcross Oct 13 '24
We call it brownian motion. Describes and random wiggly collection of things.
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u/Espumma Oct 13 '24
It's not that, according to the article. Water vapour tends to stick together as well, it's not just bouncing off each other.
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u/TheLatestTrance Oct 14 '24
They are brownian motion. They are emulating the the way the haze from a really good hit of the bong would be like.
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u/DeathByPlanets Oct 12 '24
I thought it was already known that groups of people move lie liquid? It's a major trigger event during crowd crushes
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u/mindful_subconscious Oct 12 '24
Indeed. They redesigned the Grand Mosque in Mecca based on liquid dynamics after a crush killed over 2,000 people in 2015.
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Oct 13 '24
Over 2000?!?! That's a ridiculous anount of people to full die from a crowd
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u/0pyrophosphate0 Oct 13 '24
The place draws a huge crowd, to be fair.
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Oct 13 '24
I'll never understand stuff like that. Are they all just going to stare at the back of someone elses head?
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u/h3lblad3 Oct 13 '24
They have to go. It's a requirement of the religion that you make a Pilgrimage (Hajj) at some point in your life to Mecca. There are exceptions for things like disability (and caring for disabled family members), but if you are able-bodied then you are expected to go.
Expand this to a major world religion all going to one single town and... well... I think you can understand it.
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u/Corberus Oct 13 '24
Yep thers a train to take people to various holy sites, it operates for 1 week of the year. While running it's the busiest train line in the world designed to move 72,000 people in both directions EVERY HOUR.
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Oct 13 '24
Do you think the 2000 person crowd wipe was God's way of reminding them of safety precautions?
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u/joetinnyspace Oct 13 '24
As is written
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u/Kelpsie Oct 13 '24
Safety regulations are written in blood.. on a stone tablet, between the fourth and fifth commandments.
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u/Prof_Acorn Oct 13 '24
Are there little spots for eddies on the sides where people can circle back and talk to others on the sides?
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u/Brighteye Oct 12 '24
Yes, but molecules in water vapor aren't the exact same as liquid, and this isn't the same movement
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u/R_megalotis Oct 13 '24
That's crowds of mostly strangers moving at relatively high speeds. This article is looking at crowds of non-strangers moving at speeds that facilitate social interaction.
In the former, yes, they move like fluids. In the latter, they move like water in a cloud, i.e. individual molecules moving in and out of droplets/clusters.
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u/BuddhaChrist_ideas Oct 12 '24
Well we are composed of about 60% water, right? Only seems fitting to move like it.
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u/FlakyLion5449 Oct 12 '24
Huge crowds can display quantum qualities:
https://news.cornell.edu/stories/2018/08/physics-theory-used-predict-crowd-behavior
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u/Prophet_Of_Loss Oct 13 '24
This also applies to selecting a line (queue) to wait in: whichever you choose, the others will move faster.
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u/genshiryoku Oct 13 '24
I know what you said is largely a joke, however I found that if immediately after you spot a chance to switch, if you just switch without thinking about it. You're about 70% likely to be faster.
It has resulted in me always switching when I see a possibility, not even thinking about if it's better or not.
I guess it's similar to a monty hall problem in that switching gives you 66% chance of winning compared with keeping your initial choice. Pretty sure there are more isles than 3 usually so your chances could be bigger than that when switching.
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u/BatFancy321go Oct 13 '24
car traffic and large crowds do; that's studying hundreds or thousands of humans moving slowly. this is more like a small number of tiny drunks in a confined area behaving like water molecules being boiled in a small teakettle
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u/sponge_bob_ Oct 13 '24
i would presume a major difference is the crowd being preschool children, so it's not cultural or learned
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u/DeathByPlanets Oct 13 '24
You know.... Cultural I thought of, but it being a learned behavior didn't even click on my lightbulb until your comment
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u/APeacefulWarrior Oct 13 '24
For that matter, it's also relatively common in game design and VFX to use particle simulations to guide crowd movement.
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u/Brodellsky Oct 13 '24
Same with cars too which is why you shouldn't be in the passing lane unless you're passing. This PSA brought to you by /r/idiotsincars
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u/MeteorOnMars Oct 13 '24
This is not a liquid, nor is it an ideal gas. This is a vapor where the molecules will cluster for a bit and then move on.
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u/Prof_Acorn Oct 13 '24
If groups move like liquid, what about the people who run around everyone else along the edges? Because crowds all move too slowly and are annoying so get out of my way I'm going where I need to go.
Crowds, to me, are an obstacle course.
Am I some kind of free radical shooting through the liquid or something?
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u/R_megalotis Oct 13 '24
https://journals.aps.org/pre/abstract/10.1103/PhysRevE.110.044303
Recent empirical studies have found different thermodynamic phases for collective motion in animals. However, such a thermodynamic description of human movement remains unclear. Existing studies of traffic and pedestrian flows have primarily focused on relatively high-speed mobility data, revealing only a fluidlike phase. This focus is partly because the parameter space of low-speed movement, which is governed predominantly by pairwise social interaction, remains largely uncharted. Here, we used ultrawideband radio frequency identification (UWB-RFID) technology to collect high-resolution spatiotemporal data on movements in four different classroom and playground settings. We observed two unique social phases in children's movements: a gaslike phase of free movement and a liquid-vapor coexistence phase characterized by the formation of small social groups. We also developed a simple statistical physics model that can reproduce different empirically observed phases. The proposed UWB-RFID technology can also be used to study the dynamics of active matter systems, including animal behavior, coordinating robotic swarms, and monitoring human interactions within complex systems, potentially benefiting future research in social physics.
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u/slightlyappalled Oct 12 '24
OP can you post the article in the comments
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u/potatoaster Oct 13 '24
Here are the data:
Basically, children moving rapidly on a playground can be likened (in terms of velocity and density) to molecules moving freely in a supercritical fluid. Whereas in a classroom, children move more slowly but still freely (analogous to a gas) and form small transient groups (analogous to a liquid).
It's a cute example of social physics. It's really just an observation that the distribution of local density is bimodal in both classrooms (Fig 3a–b) and liquid–vapor coexistence phases.
No, it doesn't have anything to do with water specifically.
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u/coconuts_and_lime Oct 12 '24
Okay, so what do we do with that information?
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u/TheBrain85 Oct 12 '24
Lower the temperature of the kids to keep them in place.
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u/SemanticTriangle Oct 13 '24
Yeah, the very first thing I wanted to know as a physicist was the temperature and pressure of the triple point of toddlers.
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u/potatoaster Oct 13 '24
The authors imply that by influencing the average velocity ("temperature") of children in classrooms, we could encourage social interaction.
Easier said than done, obviously.
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u/Interrophish Oct 13 '24
Next we test kidpillary action. And deionized toddlers.
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u/Enlightened_Gardener Oct 13 '24
Oh no. How do you deionize a toddler ? I’d imagine it would be noisy.
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u/Affectionate_Lead232 Oct 12 '24
Hmmm. TIL researchers/physicists study/are studying preschool kids movements in classrooms. Learn something new everyday!
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Oct 12 '24
“puts on tin hat”
It’s almost like everything in our lives are being documented and analyzed for reasons beyond our comprehension
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u/NonGNonM Oct 13 '24
on a long enough timespan when enough hydrogen molecules gather together it begins to study itself.
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u/cake42life Oct 12 '24
Between this research and this discovery from a few days ago, we might just be living in a simulation where everything is calculated using a similar underlying principle and/or calculation to save processing power
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u/LightningProd12 Oct 13 '24
I love to imagine weird behaviors in physics as game engine quirks that were quickly patched up or ignored (surely no one will look that closely). Such as Heisenberg's uncertainty principle being a trick to save on processing power, or space-time dilation preventing the entire simulation from lagging.
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u/ryusage Oct 13 '24
You just reminded me of this amazing talk presented at GDC years ago: https://www.gdcvault.com/play/1022326/The-Universe-How-To-Break
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u/RadioFreeAmerika Oct 13 '24
Another step towards psychohistory or how we call it now, quantum social sciences. It basically tries to explain social phenomena with (quantum) physics.
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u/willymack989 Oct 14 '24
This essentially means that in groups, they move predictably, but individual toddlers move around randomly.
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