thanks to brilliant for helping support this episode hey crazies quantum mechanics is best explained when you can judge your audience in real time so i thought i'd come at this a different way than usual by trying to explain it to my wife if a person is not experimentally measuring it then what is a measurement very good question [Music] this episode was made possible by generous supporters on patreon i guess first off what do you know about quantum mechanics to begin with good question not much i took intro physics in college and then i've been you
know with you for a while i mean it comes up occasionally when we're talking and whatnot quantum mechanics has to do with probabilities and things i don't know appearing and disappearing and and tangling and sure i don't know i think that's i think it sounds pretty typical okay basically the idea is that particles or at least the behavior of particles is described by waves now we don't necessarily mean the waves that you're used to thinking about like nice wave shapes on water or something it's a little more abstract than that a wave is just a
solution to a wave equation equation and we've decided that something like schrodinger's equation is a wave equation and so even though there are solutions to it that don't look like traditional waves we call them waves anyway you kind of do this in physics where like you're we're going to use the word wave but it's not a wave it's the same thing that you do with spin right yeah it's not spin nothing's spinning but we're gonna use the word spin and we're just gonna go with that very very simple solutions to schrodinger's equation do look like
waves but it's it's not universal sure but it's not universal for physics does it even matter that's fair fair complaint so they're described by waves but what's really going on is like you said it's a probability thing so the solutions are what we call probability distributions right and so they're just i'm nodding like i'm like yes probability distributions i understand what that is right no no these are words that i know what they mean but i don't know what they mean together in this context yeah so we're all clear on this so yeah so the
probability distributions now those distributions they can be distributed over lots of different properties but usually it's across space like position location that sort of thing so you get maps like atomic orbitals and stuff the things you usually see um when we talk about the probability of an electron as long as we're not observing it right well we're going to get to that okay this this is going to be very important for today today's topic okay when we have this wave model that describes how a particle exists or what how you know how it's behaving or
how it's going to behave we often say that the particle could be in multiple states simultaneously which is is a gross misinterpretation or misrepresentation of what quantum mechanics actually says which you know what we'll probably get to in a future video it's just that the states of these particles they don't exist like normal things exist welcome to quantum mechanics right here we are and so things are just weird they're weird i'm sure it can be difficult to understand and explain to the normal population that only has that only has normal like science to work with
you know what i mean if things don't exist the way that we expect them to exist i'm sure that that's very confusing for the rest of us right so we say this this particle exists in a superposition of states but that superposition is one state it's not multiple states it is one existence for that particle it's just that that existence doesn't make classical sense right it's that superposition is a combination of multiple classical states the kind of states that we'd expect a ball to be in i mean i feel like you're really splitting hairs though
to say that like well it's not existing in multiple states at the same time it is existing in one state that is all of the states at the same time i mean right well it's it's a real actual single state that is a combination of physics states that we would understand pre you know relativity and quantum mechanics but what quantum mechanics has shown us is that there are other single states that exist that we don't understand okay so not even talking about superpositions or we are no we always what we're talking about a superposition is
a single state that just doesn't make sense to our our eight brains is it like four dimensions if you will how like we get three dimensions when we start talking about higher dimensions we just really struggle with like understanding what that's like and how that works yeah that's that's exactly it so so these particles exist in a way that violates our intuitions there's one major problem and it's called the measurement problem okay quantum particles can behave in a couple different ways okay there's a very nice steady controlled way which is when the wave form evolves
over time it changes over time very gradually according to something like schrodinger's equation the other possibility is we take a measurement now the word measurement has some ambiguity to it okay it seems to imply a person needs to be involved and there needs to be an experiment which is not necessarily true if a person is not experimentally measuring it then what is a measurement very good question i would say that a measurement is any particle interaction that releases information about a quantum system to the surrounding environment now that environment might be a lab with a
person in it but it doesn't have to be is this similar to like if a tree falls in the forest does it make a sound type of thing like it produces sound waves even if no one's there to hear it like this produces information even if no one uh gather it not exactly future nick butting in here for a minute her analogy about the tree making a sound is actually much better than i gave it credit for while we were filming now that i'm editing the video i realized i was a bit too dismissive of
it and i wanted to point that out okay back to the conversation i just we're trying to define a measurement like this so that quantum mechanics doesn't sound like magic right it's not like human beings are looking at the situation and we're like we're going to look at this and see what it's doing and then it changes like we're not affecting the physics of the problem right of the of the experiment it's just happening because of like the way that we're measuring it in order to measure something about an electron we have to do something
like shoot photons at it okay and it's the photon that's making the measurement happen not the person so that measurement would happen if a person shot the photon or if the sun shot the photon exactly is the point here exactly as long as those circumstances took place for that electron and photon interaction it's considered a measurement okay again with like using words yeah don't mean what we think that they mean the problem we run into what we call the measurement problem is that even if a particle like an electron is in a superposition of of
states a superposition state i should say right because it's just one state right it's just one state if it exists in a superposition state if we look at it if we try to take a measurement try to shoot photons at it we will not see that superposition we will only see a single classical state one of the parts of the superposition it's like it collapses yes uh in fact we call it wave function collapse got it and this is a big problem mainly because this collapse this wave function collapse in order for it to make
sense it has to happen instantaneously so it's not a gradual shift right and so because it happens instantaneously and we know from our experience with the rest of physics that nothing happens instantaneously right that it's a major problem okay is it a problem or is it just the way that quantum mechanics works and you just have to accept that that it's this is a weird science that does not act the way that you expect it to act that is a way that some people handle this but not a way that everyone handles this and so
which way do you handle this oh uh we'll get to my personal opinion later okay quantum mechanics sort of brings to light a discrepancy in how people view physics sure we like to view physics as though we're finding some deeper understanding about the universe but it's not really what physics is about physics is about making predictions okay right we want to be able to science is about making predictions right right well exactly so this what we try to do in physics is we try to come up with a model that's going to predict future behaviors
of things right so in this case quantum mechanics is predicting future behaviors of quantums or you know little quantum particles right okay it allows us to make accurate predictions correct using this branch of science right all right i'm gonna stop the conversation there before this turns into a 45 minute video if you want to hear us chat about interpretations of quantum mechanics let us know in the comments and i'll upload the rest of the conversation thanks for liking and sharing this video a special thanks goes out to supporters like medic hurts who's pledging at the
asylum orderly level on patreon don't forget to subscribe if you'd like to keep up with us and until next time remember it's okay to be a little crazy if you want to learn more about quantum mechanics you should try out the quantum objects course available on brilliant it starts out teaching you how quantum measurements are made when you're ready you can move on and learn all about the mathematical foundations brilliant is a website and app that makes learning accessible and fun their courses are laid out like a story and broken down into pieces so you
can tackle them one bit at a time and there are over 60 courses to choose from so there's something for everyone brilliant helps you achieve your goals in stem starting with one small commitment to learning and building up to long-term challenge and growth if this sounds like a service you'd like to use go to brilliant.org science asylum today the first 200 subscribers will get 20 off an annual subscription you forgot to yell about conservation of energy i forgot a lot of things in that last video but if it makes you feel any better conservation of
energy shall not be violated and thanks for watching
