What is emergence? What does "emergent" mean?

the word emerging is often used colloquially to mean something like giving rise to or becoming apparent but emerging emergent and emergence are also technical terms so today I want to explain what physicists mean by emergence which is also the way that the expression is often but not always used by philosophers emergent broadly speaking refers to novel types of behavior and systems with many interacting constituents a good example is the illa-allah wave that you sometimes see in the audience of sporting events it's not something you can do alone it only becomes possible because of the interactions between people and their neighbors indeed something very similar happens in many condensed matter systems in these systems the interactions between atomic constituents give rise to certain types of collective behavior these can be waves like with la Ola the simplest example of this are sound waves sound waves are really just a simple collective description for atoms in a gas that move periodically and so create a propagating mode but we know that in quantum mechanics waves are also particles and the other way around this is why in condensed matter systems one can have quasi particles which behave like particles with quantum properties and wave behavior and all that but are actually a collective that moves together quasi particles are emergent from the interactions of many fundamental particles and this is really the most relevant property of emergence something is emergent if it comes about from the collective behavior of many constituents of a system be that people are atoms if something is emergent it doesn't even make sense to speak about it for individual elements of the system there are a lot of quantities in physics which are emergent think for example of conductivity conductivity is the ability of a system to transport currents from one end to another it's a property of materials but it does not make sense to speak of the conductivity of a single electron it's the same for viscosity elasticity even something as seemingly simple as the color of a material color is not a property you find if you take apart a painting into elementary particles it comes from the bent structure of molecules it's an emergent property you will find that philosophers discuss two types of emergence there is strong emergence and weak emergence what I just talked about is weak emergence weak emergence means that the emergent property can be derived from the properties of the system's constituents and the interactions between the constituents an electron or quark may not have a conductivity but in principle you can calculate how they form atoms and molecules and metals and then the conductivity is a consequence of this in physics the only type of emergence we have is weak emergence with strong emergence philosophers refer to the hypothetical possibility that a system with many constituents displace a novel behavior which cannot be derived from the properties and the interactions of the constituents while this is logically possible there is not a single known example for this in the real world the best analogy I can think of a photographic mosaics there are photos made up of smaller photos if I gave you all the individual photos and the properties you'd have no idea what the emerging picture will be however this example is hardly a natural phenomenon to make a photographic mosaic you start with the emergent image you want to get and then you look for photos that will fit in other words the strong emergence which you have here works only thanks to an intelligent designer who had a master plan the problem with strong emergence is not only that we have no scientific theory for it it's worse strong emergence is incompatible with what we already know about the laws of nature that's because if you think that strong emergence can really happen then this necessarily implies that there will be objects in this world whose behavior is in conflict with the standard model of particle physics if that was not so then really it would not be strong emergence a lot of people seem to think that consciousness of free will should be strongly emergent but there's absolutely no reason to think that this is the case for all we currently know consciousness is weakly emergent as any other collective phenomenon in large systems thanks for watching see you next week

Channel: Sabine Hossenfelder

Views: 122,316

Keywords: science, physics, what is emergence, what is emergent, what means emerging, reductionism, strong emergence, weak emergence, philosophy, what is strong emergence, what is weak emergence, quasi-particle, particle physics, hossenfelder, emergence

Id: bJE6-VTdbjw

Length: 4min 59sec (299 seconds)

Published: Fri Apr 03 2020