What Are Particles? Do They ACTUALLY Exist?!

is where things are going to get a little weird I love it when things are weird good to know that nothing we've talked about so far has been weird yeah okay [Music] hey crazies welcome to another episode of wife reacts this is my wife awkward M hello this video is going to be an overview of something we call Quantum field Theory or qft for short basically it's what is the nature of matter why did we invent Quantum Fields you know what was the motivation behind it that that sort of thing so I guess let's start with uh what exactly do you know about Quantum field Theory I was afraid you were going to ask me this question uh almost nothing if it has to do with Quantum particles I'm gonna go out on a limb here where they come from where they go if I had to guess but I really don't know so we're starting from a pretty basic basic set of knowledge here right yes what is this it's a ball it's a ball so just like anything else this ball is made of materials which are then made of molecules which are then made of atoms which are then made of subatomic particles we can just sort of break this down right it's a method we call reductionism we reduce it into its fundamental parts now if we reduce everything in the universe into its fundamental or Elementary Parts okay what we get is a set of Elementary particles sure this is all of the fundamental or Elementary particles that we are aware of yep and it's a pretty small list technically every single one of these has a anti-particle most of the things that we experience we we interact with on a daily basis us all the objects around us and so on with very very few exceptions are made of three of these particles the up Quark the down quark and the electron sure that's it yeah and those things tend to interact with each other via photons those are sort of the four Elementary particles that we ever interact with light as we saw from the particle chart is made of photons these particles yes what other way do we model photons as what other way do we model light as I should say and if you go all the way back to yeah we model it as waves right so an electromagnetic wave is a disturbance in something we call the electromagnetic field and that looks something like this yes I am familiar with this animation right so an oldie but a good it only but a goodie this is one of my faves in this animation you've essentially got all these points across space and each point has a value attached to some kind of quantity in this case vectors but there's a quantity attached to every point in space and that's what we refer to as feel that's what a field is sure what we did back in the the late 1800s as we modeled light as a disturbance in that field we do this with lots of things it's not just with electromagnetism we can do it with the pressure in a water tank right we can assign a pressure value to every single point inside the tank we can do it with temperature we can do it with temperature absolutely when we set up these values as a field it opens up an entire division of mathematics that we can use on it yeah okay to what I've always wanted it's a really big deal we can calculate things like divergences and curls and gradients and so if we can set up a scenario as a field it's very useful it's a very useful tool doesn't mean that the field is something that exists it's just a collection of numbers okay but it's a very powerful tool sure the particle concept of a photon rolled around in like the early 1900s we started to think that oh well maybe everything is a particle and it only looks like it's a disturbance in a field as we leaned into the particle model we started to run into problems right we started to run into not being able to incorporate relativity and having to put patches on to explain the hydrogen atom and people started to ask the question well like what if particles aren't how matter Works what if particles are the illusion and they're actually waves and they're actually disturbances disturbances we say waves but waves is kind of it can be misleading if you're not familiar with the concept already do we say waves like we say spin no it's not that bad okay but if you want to call any disturbance in some medium a wave sure but I think it might give someone who isn't necessarily familiar with physics the wrong impression okay see because like okay this is a good question this is a great question when you hear the word wave you probably think of you know like a full wave maybe than the surface of some water or something a wave on a string maybe but in physics we tend to call any disturbance in uh some substance or medium or whatever a wave so even if it's like boom and it's a pulse that's traveling along a string that's still considered a wave it's still described by the same mathematics I'm comfortable with that yeah that's okay it's still real right and so you gotta kind of be a little more vague just because it's not repeating doesn't mean that a wave does not exist right it's still the same it's still the same phenomenon even if it's one right I'm gonna stop beating around the bush and we're going to talk about exactly what a Quantum field is yes let's Okay we already saw the electromagnetic field where there was this you know vector or Arrow attached to every point in space what if particles are the illusion and matter behaves as disturbances and Fields instead okay rather than some value of some measurement being attached to every point in space it was essentially existence attached to every point in space existence existence of what we would perceive as a particle any particle any elementary particle yes okay yeah it's not like only electrons are found in the electron field and only of quarks of quarks yes are found in the up Quark field that's that's how it is that is how it is yes they each get their own field okay but an up Quark in an anti-up Quark are in the same field an electron and an anti-electron are in the same field also known as a posteron correct okay every point in space has an existence value essentially and you can see that each of those points are wiggling every point is wiggling sure that's sort of the quantum uncertainty going on here right if there's a large enough disturbance a full disturbance in this field we perceive that disturbance as a particle okay so if there's a disturbance in the electron field it might be an electron or a positron depending on what the disturbance looks like okay if is a disturbance in the photon field then what we're going to see is a photon sure we're going to observe that as a photon even though the photon isn't really there there's no really particle there it's just a disturbance in a field is there an anti-photon yes but the anti-photon is just a photon photons are wild yeah okay it is its own anti-particle but yes every particle has an anti-particle it just might be itself I'm not here for that but okay with this graph s that it makes space look like it's discrete like there are these little pieces and they have size right which is not really how it works it's kind of misrepresenting it a little bit but when I made this graphic like what five years ago I didn't really have the animation skill to do better to do better right but now a real Quantum field is continuous there would be a disturbance at an individual point in a continuous space okay rather than a box being up higher than the rest of the boxes what you see is a spike in a surface which might be called a wave if you will yes we would treat this Spike that moves around as a wave pulse it's just a disturbance in the electron field for example in this case electric charge is represented by color red for positive and purple for negative and Quantum spin orientation is represented by the vertical Direction up for a spin up and down for spin down it's a representation that it's not really going up and down these fields are actually 3 dimensional but if I showed you a three-dimensional version of this your eyes and brain would just be overwhelmed and it wouldn't be useful sure something we do in physics is we suppress dimensions in order to make sense of things this is very common I'm comfortable with that honestly in this case three-dimensional space has been compressed into a two-dimensional plane and we're using that Dimension we suppressed as a way to show other information like Quantum spin for example and it's not like the fields occupy different places in space they all occupy all space correct yes they're all like coexisting they all coexist and overlap each other right which allows particle interactions to happen because then energy can be exchanged between Fields if you have an electron and a positron come together at the same spot what you get is antimatter Annihilation ah okay which is how that works sure they just cancel each other they just cancel each other out because they have opposite values and it essentially turns the quantum field to a zero value or what we would call the vacuum state of the field and by doing that by by assigning existence to every point in space you're essentially assigning all possible properties for those particles for those things we perceive as particles into that spot all the information is there it has to be right sure because existence is there and so this is kind of what separates a Quantum field from a regular old field like the electromagnetic field poor electromagnetic fields an old regular field there's some debate over whether or not these Quantum Fields actually exist but the usefulness and accuracy of the model was kind of hard to argue with does anything actually exist I mean like I mean we know light exists and we know matter definitely exists which is the point to this video we're going to come back to that but matter definitely exists it is not an illusion we try to represent it in different ways depending on what we need to predict 1949 rolls around and this one guy famous guy named Richard Feynman enters the scene for a while we have been doing these Quantum field calculations and they're real nasty We're not gonna do any today it's not that's not what this video is about so he came up with something that we now call Feynman diagrams that's what it is I'm like I'm sure I've heard you talk about this before okay right but they're basically space-time diagrams which I've done a ton of videos about most of the information from those videos you don't actually need to understand this you just need to understand that like time is on the picture he didn't necessarily in this paper come up with a way to represent all types of particles in it and one of these diagrams he didn't even know about quarks sure at the time nobody did but he did come up with a way for things like electrons and positrons to interact with photons which is what we've been talking about this entire video If particles come together and interact we want to be able to represent that and be able to calculate what's going to happen with Quantum Fields you know how are things going to go in and how are things going to go out straight up is time is the time axis okay and so as these two particles come together they do some kind of interaction and then particles then come out and we want to be able to predict exactly how this is going to take place we can see that in we can see the out like what happened inside of this black box this unknown area is it important that the lines are angled yeah because they're they're the particles are coming together gotcha horizontal of space okay bring it together and then going apart yes gotcha okay so these particles somehow interacted maybe this was like two electrons coming together and then repelling each other for a while we would go through start from like fundamental principles and we would go through all the nasty Quantum field Theory calculations and figure out what's going to happen it was so absurdly difficult the jiggly spots is the vacuum state of the quantum field what if we can pretend that those wiggles and jiggles are particles because if they're not necessarily zero but they're not like a whole occupation of a spot they're not so they're not actual particles but maybe we can pretend they're particles something that we now call virtual particles they're not actually particles but we can pretend that they are if we do that then we can start to simplify the math a little bit maybe when the two electrons come together a photon bounces between them and allows them to repel they're they're maybe they're interacting with this Photon this photon is not a real Photon it's inside that black box oh the only actual particles here are the two electrons coming in and going out okay the problem is this box is unknown and there are other possibilities other ways that these part these electrons can interact with each other via these virtual particles okay we can imagine a more complicated scenario maybe they exchange two photons two virtual photons they're always virtual because it's in the box if it's in the black box it's virtual okay unless it went in or came out it's not a real particle and also maybe they exchanged two photons or maybe a photon jumped out of one and jumped back in before they exchanged a photon or you know maybe they they went to exchange a photon but that Photon decayed into an electron positron pair before becoming a photon again before hitting the other electron so all of these different scenarios are possible scenarios okay and because the boxes are known and these are virtual particles we need a way to account for all of them what it did was it took this huge nasty calculation that could be really cumbersome and almost impossible sometimes and it turned it into a bunch of little calculations that are fairly calculable okay and then all you got to do is add the results together how many different options are in the Box an infinite number yeah so it doesn't feel doable right when you have to calculate every one of them that's that's a great question actually as it turns out something that Feynman discovered while he was playing around with this he was like well I mean I don't have to calculate all of them it just seems like a lot you know so what he did was he really realize that as he calculated them the more complicated they were the smaller of a contribution it made to the calculation each of these diagrams has a number of these dots that we refer to as vertexes or vertices okay the number of vertices is a way to determine how much of a contribution that scenario is going to make some point you can just stop because the the the terms aren't making any contributions contributions to your calculation it's going to be negligible right you're going to be close enough something you might have noticed in those diagrams is that there's really only one type of vertex every single one of these vertexes has two straight lines at a wiggly line that that's that's all that can exist in what we call Quantum electrodynamics which is a type of quantum field theory is where things are going to get a little weird oh excellent I love it when things are weird good to know that nothing we've talked about so far has been weird yeah okay what you've got here is you've got an electron coming in and here's the weird part this is a positron coming in even though the arrow points the wrong way that's what tells us it's a positron you have a question how do you know if you're dealing with an electron or a positron via the diagram if it looks exactly the same because in a Feynman diagram we represent antimatter as matter going backward in time uh okay and so any arrows that point backward in time are anti-particles why do we represent it that way because it makes the math work out it's a time they're not yeah and not even Feynman thought that he didn't actually see he he made a point to say like I don't actually think anti-particles are are particles going backward in time that's ridiculous I feel like he's taking a lot of Liberties yeah with like the virtual particles and the backwards in time now and it's making me feel like it is less reputable he viewed this as just a tool for solving Quantum field Theory problems he didn't view this as reality how do you know if the answer to your problem is correct or not because you can check it how experimentally ah okay we've seen that this gives us answers that match reality okay I'm more comfortable with it then okay okay so here's one scenario you've got an electron and a positron coming together annihilating and making a photon okay okay does that make sense yes okay so they annihilate each other they go to zero but the energy has to go somewhere and so it gets kind of shunted into the photon field but if I turn this now we've got an electron coming in an electron going out and Photon going out so now we have enough we have an electron emitting a photon and changing direction gotcha it's a y yeah okay we have an electron absorbing a photon and then changing direction but still an electron but still an electron both the arrows are pointed up in time yep what do we have here a photon coming in and dividing into an electron and a positron exactly yeah see see this is huh this is how you read these diagrams so once you know the rules you can kind of figure it out right and so you just keep going so here we have a similar scenario that we had before but it's a positron this time positron comes in absorbs a photon and changes Direction okay here we've got a positron that emits a photon and changes Direction it's no oh okay and then we're back to the beginning so like those are the scenarios those are the only scenarios that can happen in what we call Quantum electrodynamics okay does that make sense and then you can have variations of this that get more complicated right you can just combine a bunch of these together and how many of these you combine together determines how big of a contribution it makes okay purpose of quantum field Theory it is to predict how these particles will interact it's about particle interactions if there are no particle interactions Quantum field theory is kind of useless sure and so what the standard model tells us is that different particles different fields interact in different ways sense and we we do the calculations using things like Feynman diagrams okay we know this racquetball exists we know that it's made up of fundamental Parts Elementary parts that interact and we can we know what those interactions look like this Elementary Parts might be particles they might be ways they might be disturbances in fields but at the end of the day they are real things we're just debating over what kind of real thing they are matter does exist it just wasn't what we originally thought it was welcome to science yeah and until next time remember it's okay to be a little crazy the Multiverse isn't scientific why are you even talking about it it may not be testable so we can't call it a scientific fact but it's still scientific it's based on time-tested models and it's important to explore the extremes of our models that's where all the theoretical Discovery happens anyway thanks for watching

Channel: The Science Asylum

Views: 200,930

Keywords:

Id: zS2vI_2faII

Length: 19min 35sec (1175 seconds)

Published: Mon May 01 2023