How Science Predicts Emergence in Humans & Animals!

humans are pretty complicated creatures right so if we want to understand and predict our Behavior you'd think we'd need a pretty complicated model after all they're people who spend their entire careers in subjects like psychology and sociology to try to figure out all the complex ways we operate what if I were to tell you that no all you really need to understand most human behavior is physics now this might seem outrageous or even insulting to suggest that you and I can be regarded as a collection of particles just responding to Mechanical forces but before you get too judgmental let me show you what I'm talking about I'm going to show you how shockingly far we can go in understanding the behavior of crowds traffic and pedestrians using principles borrowed from physics and you'll also see how those same ideas that apply to groups of humans can also explain what had been some of the most mysterious group behaviors we see in other animals from flocks of birds to schools of fish stick around because that's coming out right now now before we get into it I'd like to recommend a documentary that I think will really help you get a great feel for group behavior and other animals in this case from the point of view of birds the documentary is called migrating birds Scouts of Distant Worlds it's available on Magellan TV today's sponsor some of the fascinating things I learned from this documentary is how group behavior of birds can actually debilitate a predator how flying in certain group formations allows Birds to migrate farther and how groups of thousands of birds can change course in an instant simply by individuals following just seven of their closest neighbors Magellan TV is completely ad-free and includes a growing collection of new 4k videos added weekly you can actually watch this documentary and the rest of Magellan TV's extensive collection of over 3 000 plus documentaries for free right now just click the special link in the description or type the URL that's right here on your screen now let's get back to how all this fits with crowd physics we go about our daily lives planning talking to one another weighing decisions responding to unexpected events it's kind of complicated Being Human if we zoom out from our lives and take a wider bird's eye view all those little details don't seem to matter much everyone in a crowd has their own thoughts and plans and problems but they don't seem to make much of a difference to what the whole crowd does together when we watch many people moving around over a long time we can start to see patterns and regularities that aren't evident if you follow just one person this is a bit like what we find when we look at stuff that isn't alive a gas say made up of countless particles too small to see if we track a single particle it seems to move around at random shifting this way and that because of all the collisions it has with other particles we can't really predict what it will do at some point in the future but if we zoom out and look at the trillions upon trillions of particles then we can identify some simple laws and use them to make very accurate predictions for example we can see that for a given volume of gas in a closed box the hotter it gets the higher its pressure and we can write down equations that will predict precisely what the pressure will be if we know some other conditions this is the case even though again the individual particles are bouncing around like crazy to go from Individual particles to the properties of a whole cloud of gas we need to think about averages it doesn't really matter what each particle does on its own All That Matters to understand properties like pressure is what they do on average so we need to look at the statistics of all those motions for example what proportions of the molecules have different energies and velocities and how those statistical distributions change if we say heat the gas up this approach is called kinetic theory of gases and it was developed in late 19th century by the physicist James Clark Maxwell and Ludwig boltzmann it evolved into the science not called statistical mechanics or just statistical physics in 1971 a mechanical engineer at the University of Sydney named Leroy Henderson wondered whether some of the concepts that scientists use to understand gases might be applied to human crowds Henderson measured the speeds of people moving in crowds in public spaces in Sydney walking around the University campus or Street intersections and children and playgrounds he found that in all these cases the distribution of speeds looked just like those that Maxwell and boltzmann had assumed for the speeds of particles in a gas now we know that one thing a gas can do if you cool it down or if you squeeze it is to condense into a liquid in liquids the particles still move quite randomly but they're much more densely packed and they bump into each other more often the switch from a gas to a liquid happens quite Suddenly at the condensation temperature and this is called a phase transition Henderson wondered if crowds might undergo phase transitions too from a crowd gas to a crowd liquid for example if they get squeezed together at a ticket barrier in the late 1980s physicist Dirk hubing at the University of Gottingen in Germany thought that Henderson's gas model of crowds might be a good starting point for a more sophisticated theory of how pedestrians and crowds move about particles and gases and liquids interact with one another they attract over long distances but repel each other when they come very close that might seem very different to how people interact when they move about but is it really when two people walking in opposite directions on the sidewalk get close they Veer past each other to avoid a collision as long as they're paying attention it looks like some short range repulsive Force has kept them from colliding there's not really such a force that we could measure with a meter but helping and his colleague Peter Molnar figured that if they made a computer model that represents people as particles interacting through a repulsive Force they might move in much the same way they do in real life in 1995 the pier ran computer simulations of how such people particles if you will behave when crowds of them move in opposite directions down a corridor they found that people organize themselves spontaneously into counter flowing streams in which some followed behind other in the line and that's exactly what we do for example when we're moving along a crowded sidewalk we're certainly not just Mindless particles but in this situation it looks as though we might as well be physicists call this Collective Behavior where particles seem to coordinate what they do there was nothing built into the model to enforce it the people only interacted through the repulsive Collision avoiding Force yet this Collective way of moving looks intelligent because it means that there is less chance of collisions than if every particle blindly follows its own independent path in other words what looks like a kind of intelligent Behavior emerges from a model in which the simulated people by the way they are usually called agents have no intelligence whatsoever these simulations of pedestrians show the phenomena called emergence where some Behavior or structure emerges from a complex system of many interacting components from the interactions among them even though those interactions themselves might be very simple and contain no hint of that Collective pattern classic phase transitions like freezing and evaporating are also examples of emergence it's not at all obvious if you look at the forces between water molecules that they will suddenly all freeze into ice at exactly the same temperature but they do compared to pedestrian motion road traffic is an even simpler and more constrained situation because we're Bound by the law to stay on the right side of the road moving one after another in single file so it's not surprising that agent-based models are now being widely used to understand and predict road traffic these models just assumed that the agents drivers in their vehicles try to go in One Direction at the speed they prefer but to slow down if necessary to avoid colliding with the car in front as if there's a repulsive force between them with no more ingredients than this these traffic models can produce amazingly complex Behavior if the traffic is very light each vehicle moves just as it pleases hardly interacting with others like a kind of traffic gas but above a certain threshold in traffic density how many vehicles there are on each mile of road there's a switch to a sort of traffic liquid where everyone keeps moving quite smoothly even though the flow is quite dense if the density increases a bit more there's another transition to a traffic solid you probably all know what that's like because you've all been in one it's a traffic jam in which the vehicles barely move at all once the traffic density is high enough for a jam to form it doesn't take much to trigger it just one little disturbance to the fluid Light Flow like a single driver breaking too suddenly might be enough that little disturbance might be only fleeting and so it seems to most of the other drivers that the jam doesn't have a real cause at all it's a phantom gem agent-based traffic models showed that it's just another kind of immersion Behavior but nothing we've seen so far in human crowds matches the beautiful emergent behavior in groups of other animals like the coordinated flocking of birds called a murmuration or the Predator avoiding schooling of fish this Behavior used to be such a mystery that in the early 20th century some zoologists suggested that birds have a kind of telepathy that lets them coordinate their movements but thanks to agent-based models we now know that nothing so weird is needed in 1987 computer engineer Craig Reynolds decided to see if the murmurations of blackbirds he watched in a local Cemetery in California might be mimicked in a computer program in which agent-like particles moved around according to Simple Rules Reynolds call these agents voids he suspected that the black birds were doing nothing more than responding to the movements of their neighbors they had no Global sense of the whole flock the rules for the boy's were that each would try to match its speed to the average of all those within a particular range and they would move toward the center of that local group and that they would change direction to avoid collisions that's all there is to it Reynolds Boyds did coordinate their movements like a real flock of blackbirds these simulations were so good and yet so simple that they were quickly adopted by Hollywood filmmakers for animated special effects such as a swarm of bats and Batman Returns and a herd of stampeding wildebeest in The Lion King these group movements of animals make flocks schools and packs of herds rather like a kind of fluid they seem to flow close up it might look as though the creatures are just jostling randomly but seen from afar there's often a clear pattern to the movement so these asian-based models can capture some pretty complicated movements by assuming only that the agents are being pushed and pulled by blind forces maybe now you're wondering is that really all I am just a particle bouncing this way and that because of forces that it can't even sense let alone control you're not really of course atoms and molecules can't make and watch YouTube videos but then how come the same theories that work for molecules also work for people traffic and cheap that's actually telling us something deep about the way the universe works something that gets lost when we present that question as a search for ever more fundamental theories that matter from atoms to quarks to Strings the universe we experience is filled with many things interacting and so you could say that the most fundamental physics is that which deals not with the fundamental particles but with objects interacting and the amazing thing is that this physics statistical physics is renormalizable that means we can keep bundling together groups of objects into bigger ones atoms and molecules into cells cells into people people into crowds and societies and find then the lower level details become irrelevant and the same physical phenomena like phase transitions keep happening again and again but at much bigger scales maybe you'll find that a comforting thought and not get so upset the next time the traffic freezes and you're stuck in a solid state in the traffic jam it's just physics my friend I'll see you in the next video [Music] thank you

Channel: Arvin Ash

Views: 60,231

Keywords: group behavior, physics of crowds, murmuration of starlings, flock of sheep, emergence, emergent behavior, physics of traffic, kinetic theory of gases, statistical mechanics, statistical physics, dirk helbing, leroy henderson, the emergent group behavior model, emergent group behavior, craig reynolds, crowd dynamics, crowd dynamics theory

Id: T0386SZHKAY

Length: 13min 38sec (818 seconds)

Published: Fri May 12 2023