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hello and welcome to technically speaking where scientists and Engineers come together to chat about a common interests share knowledge and satisfy some curiosity I'm Laura and in this episode I'm joined by Emma to talk about the Multiverse the underlying physics and why there are so many movies that feature it so to start off with Emma tell me something you know about this from your Physics degree I haven't per se had a module in multiverses but I've had plenty modules in quantum mechanics
and I've had some cosmology modules as well and as far as I'm aware there are those two branches of physics seem to have their own theories on multiverses and you know write them into the history and of physics and try and include them to make sense of things that don't make sense but I think quantum mechanics is a good way to um picture a lot of the physics um theories of multiverses because it's all about quantum mechanics and probability at the end of the day um
and I think it's the most fundamental Theory when it comes to um multiverses and there's many theories for Multiverse is but one of the most popular ones which also I think it's just can't come in and out of Trends as well because as I was reading about it in the 70s physicists weren't liking it but in the 50s they were and then in the 80s they weren't liking it and then now like people are starting to like it again so um now that it's trendy again we'll go
through the many world interpretation of um of physics which is that whenever you make a measurement um and you have different possibilities of results um there exists a universe where you have those different results come true and Laura are you following when I say measurement and results or should I go through more of that I vaguely remember being taught about schroding as cats and the thought experiments from my own undergrad degree I mean I did physics like 20 years ago
now and I think the way it's taught has probably changed quite a lot so the measurement is essentially you interacting with the object or the cat in some way yeah yeah so our recap shooting his cat I mean I'm actually honest I'm sure you know showing his cat but it's the classic thought experiment of you put a cat in a box with a radioactive sample and that if that sample decays and it causes a poison trap to release I mean there's many different ways that the cat
can die in different theories of schroding his cat but essentially it's probability based like the decay of a radioactive isotope and then you close the box and you can't see the cat and while you're staring at the Box you don't know if the cat is dead or if the cat's alive so you say that it's both dead and alive as a superposition of the two final States um and that's where superposition comes into it if anybody's heard that from quantum mechanics it's something two
different states or multiple States happening at the same time because you don't know but um obviously if you were to open the box you would see if the cat is dead or alive and that's where like the results from the measurements so the measurement is looking in the Box in a case of Schrodinger's cat and um to relate that to the many world interpretation is that there exists a universe where the cat is dead and where the cat is alive to put it in simple terms and then when you
make a measurement you decide which Universe you're in which I think is a good way to think about it it's a simplified version of it but it's easy to digest I think which is important when it comes to multiverses a good analogy from real life is probably something like when you get your exam results and you get the envelope and you don't know what the results are until you open that envelope so you could all have passed you could all have gotten like 100 on every exam you don't know
until you look you both passed and failed until you see the results yeah your life can go in any direction based on what's in the envelope right yeah yeah so I think I don't know I think that the many worlds has some sense because you can physically imagine that because there are two possibilities there is going to be Universe where that happens it makes sense in my head and it does seem to be more philosophical in that sense because apparently when you actually do the maths it's um a bit like
luster of maths so I don't think it was more dislike that this is the bit where I start to become a little bit confused I haven't studied maths in quite a long time and it is all very math space it's all this theoretical stuff isn't it yeah the one thing that I remember from my undergrad that's maths based is if you have a particle in a potential well and you can think of that potential well as a box that the particle can't escape from if uh by potential it just means
the amount of energy right yeah um and it's very low potential so it can't really move from the space that it currently occupies there was some math you could do to try and figure out whereabouts in that potential well that particle was but then some uncertainty came into like you know the position but you couldn't know the momentum or something like that and I don't actually remember any of the maths involved yeah yeah you just mentioned Heisenberg and Cersei principle actually the famous the
famous and put a certainty principle yeah so the potential well is essentially that like imagine something's in a box like an electron with infinitely High walls and it can't escape that box because the sides are infinite uh and they're solid and they're not moving they become a boundary condition so when you know a boundary condition on a system you can actually formulate a wave function which represents the state of the electron in the box and I know I've said a lot of
boundary conditions States I've said a lot of wave functions I've seen it all um but essentially to break down what a wave function is because I'm sure I'm sure it's been mentioned in many films probably in the wrong context as well a wave function is any function like y or f of x it's just a function that describes the state of a particle or a system uh completely like it contains all the information you could need so when you have a particle in a potential well that has a wave function
that represents it and when you mentioned you can calculate the position and the momentum you do that by performing a mathematical operation on the wave function so if you wanted to say I want to know what the position is you would use the position operator operate on the wave function and then you get the probabilities of the position back so that's a great time to stop because I've just mentioned loads of things just throw in all the jargon it now sounds like we're doing surgery
on an electron because you mentioned Opera oh yeah yeah to make things complete um Heisenberg's uncertainty principle is the you can't know the position and the momentum of an electron or of a particle to a great accuracy at the same time you can't know both you can only know one accurately and another has to be less known and uh there's that famous joke uh where it's like a police officer stops um Heisenberg for speeding and he says do you know how fast you go in and then
Heisenberg goes no but I do know where I am that's a bit of a classic one that all the physicists love that one so with the jargon of operations should I go over that a bit more I think so so I'm sort of understanding it is you do some maths to the maths essentially so that set of equations that defines your electron you can do something to those equations to give you some sort of information yeah essentially it's all if you think of it as like a broad like scope it's
essentially just probability Theory so the wave function gives you the probability of something happening and you oper use an operator determine what that something is so probability that the electrons in the middle or average position you perform the operation and then you get the probability out of the wave function honestly it's kind of harder to explain than it is to do the math I could imagine that because you're trying to visualize this thing that it's not quite accurate is it you're not
looking at like an actual like a ball inside a box necessarily which is the example we're sort of using that's sort of as close as we can get to explaining it without just looking at some equations yeah and because it all seems very Matty and it is um you can actually simplify it which does take away a bit of like the perfect accuracy of you know the math but that's what happens when you explain things um so it's not a Quantum mechanically perfect example but imagine that there's
a wave function that describes a dice so you have every information you want to know about the dice where it is what it what numbers facing up Etc and so we could apply an operator that's called the what number is facing up operator and then when we perform that on the wave function we find that there's a probability of there being each number with a Chance of one over six as you would expect and that is a quantum mechanical explanation of something that's classical though so again it's not
perfect but it just to get like the the idea of that you find you know what you want to find you apply it and then you get the probabilities of the different outcomes is essentially what the whole mass of quantum mechanics is and it's hard to understand like if you're feeling like I know if you're like scratching your head of it right now it's fine everybody everybody's like that yeah I do in a Physics degree and I'm like that right now so it's normal fair enough but I guess as
long as you can follow your way through the maths and come to the answer that's on the exam paper yeah I'm gonna keep bringing everything back to exams and getting your results now yeah I think yeah I don't have to go through that for a while though so but yeah so how does it actually apply to the Multiverse and it's the idea of the different outcomes that have different probabilities are exist in a different universe that's so when you roll a dice and you get a one
the many worlds interpretation is that you can have um different universes with two three four five six but that's like just that theory there's more theories that the like physical constants in the world are different in different universes whoa so physics is entirely different in that case yeah that's like the um cosmology Theory um which people are doing a lot more kind of research and maths into trying to find evidence for it but it's what's known as the bubble theory of um
multiverses and um it's where the universe is split into bubbles and they all have like slightly different like physical worlds so like the speed of light could be different in one of them because it happened at a different stage of inflation after the big bang again many many big words but cosmology is different physics like backgrounds and then I think the physics interpretation is just different universes see I think I'm struggling a little bit with visualizing these
bubbles in the universe where there is different physics because that sounds like a physical thing that you should be able to interact with because we're talking about bubbles things we were talking about a part to play The Box before but it's not it's not what it actually looks like because we can't see it because the physics are different yeah and also I mean that's what they're searching for like um when I was looking into it it was they were searching for gravitational waves or gravity like
evidence that there's like influence of different matter on our universe which would be from one of these bubble universes because they would also have mass and experience an attraction that's how they kind of look for it I think I mean I'm not images yeah but that would mean they'd interact in some way so there must be some crossover from that different physics at a different bubble of physics to our bubble of physics yeah I guess it depends how like how thick is
that bubble wall like how much you separated from each other but I don't know maybe I'm a bit biased but I don't I like the different universes where different things happen because that's where all the media and like Doctor Strange mods of it and like Spider-Man you can have a different actor for Spider-Man in each different Universe because that's a different outcome so that makes sense to me and I think that's what people like to hear about multiverses like no one wants to know if
the speed of light's different people want to know if tell me why is Spiderman or if Tom horns that's the real importance but I also made it made it quite easy for Doctor Strange to do certain things that's basically what he was able to do he wasn't necessarily he wasn't doing magic he was just doing physics yeah although daughter strange things that he can move between multiverses and that has absolutely no life because physical representation that I could find like
there's no way to enter a Multiverse not even buy something like quantum entanglement physics words no I don't think the sponsoring entanglement it's nice to compare superposition and quantum entanglement so superposition is when you have two states existing at the same time like the cat being done live then entanglement is when two states influence each other and so that's what Einstein called spooky action at a distance because he found that when something changed in one area it changed
something else and so they were like entangled and like the maths when you look at um an entangled wave function as well um you can see it like it looks like you can see that when you try and do the mass it just doesn't separate that's quite nice so sometimes if you guys don't understand quantum mechanics maybe the thing to do is a mathematical course on quantum mechanics and it will just clear if they're not I guess so how much maths do you need to know before that so
like I mean before I went to University I could do things like differentiation integration I vaguely remember doing stuff like little plus transforms then and I was like no um not in quantum mechanics actually we did LaPlace when we did about waves and stuff but I think integration's a strong one because you do the integration to find like the probabilities and things but I think maybe if you just if you only know integration or differentiation I think you could get very far with
quantum mechanics okay so that's the sort of maths that I'm fairly possible with I'd have to refresh my memory a little bit because I don't I haven't done that sort of thing in a long time yeah I do more more real world things that don't even require me to differentiate and integrate calculus isn't real world no but I remember again when I was doing my undergrad there was this big thing about Grand unification theories and things like string theory and all these other
things yeah like different aspects of physics that didn't necessarily quite match up and that's what Grand unification theories Were Meant to do that's one of the main problems with um this many world interpretation is people don't like it because it's um linear and the world isn't linear it's not consistent with the theories that we have and we think we know now and so people can't include it in um theories so that's why it gets disregarded the massive String Theory the theorists they
just you know spend some time doing some maths and then they just get like well the universe should have 10 dimensions and that's all I know about String Theory just 10 Dimensions but apparently there's like M Theory which is 11 dimensions and it's this M Theory that allows you to have different they're called brains but not spelled brain brain b-r-a any just to be more confusing because it's not confusing enough already yeah different brains of the universe that can support the idea of
multiverses maybe but I don't know how popular string theory is anymore so I was trying to get my head around it in preparation for this episode and I got as far as okay there are 10 Dimensions the first four are sort of up and down left and right and they're moving through time so the three space dimensions are one time Dimension and then the other ones were all like sort of almost like different iterations of the universe where something had happened at some point from The Big Bang
to make things slightly different and the further through the dimensions you got the weirder things go up essentially that's interesting because I saw some theories as well where it was there's Multiverse theories where there was different levels of the Multiverse so like level two was the universe is having different fiscal constants and then you have like it goes all the way up I think to like level four of different like variations and different types and then there's another theory with
different types of universe and then the many worlds is like what's known as a Quantum Multiverse and you have like different like holographic Multiverse that means different things so I think people just like to kind of have an idea about it because also I think very funnily having nine different types of multiverses you have multi multiverses I'm like surely Multiverse should encapsulate everyone every Universe no it's like some Infinity is bigger than all other
infinities kind of like argument that does sound a little bit odd because I guess when you see it um represented in films it is usually a character has made a decision and then this sort of they split into two different timelines yeah but it's still the same universe it's the same physics it's just one person decides to travel the world and the other one decides to stay at home and look after someone or something like that yeah I guess because that's quite a human way of explaining
what it means when you're doing this measurement and influencing something that could just be like a subsection of the Multiverse there could be another like completely different subsection where you have a different hair color for some reason and you just make exact same decisions that you've made but something's different about you but I love the split in timelines um description and media because that just reminds me of um that Rick and Morty episode where there's any sense of
uncertainty like like space-time splits and they enter different universes because that I think that's what I think whenever I think of the Multiverse I don't think of Doctor Strange I don't think of Marvel I think of Rick and Morty so maybe I'm never gonna get that out of my head maybe that's just like the way I thought about it and that's just the way it's gonna stay I feel like that means that anyone that is slightly uncertain or I guess maybe not so confident in life is just always
confused because they're always splitting into many different universes yeah whereas someone who is always certain of what they're doing has one path and that's it yeah yeah that's a good point actually maybe you're more certain than you you have like a shorter path through space-time or something I don't know that's getting confusing now though I feel like we're going down some sort of just general philosophy route and veering away from the maths of it and just thinking about what happens if
I do this yeah yeah the maps is hard though it's the philosophy that there's this that's the fun thinking point but I feel like we're going on because moldy route because that's all about like different universes like paths where you go how long are you spend in a certain area and how which time that passes for you that feels very cosmology relativity for me so maybe that's why I'm getting confused let's stick to the mass of quantum mechanics all right so I've got this
idea that if we go back to sort of my undergrad physics you have a particle in a box you've done something to it to try and take a measurement and then that sort of makes you split into one of the multiverses yeah and that's one theory of multiverses as well like if we're assuming that this many worlds is right then that's what happened which is what um it was in a lecture to some students um shoninger said like a preface of what I'm going to tell you you're not going
to believe and it's that everything that we can look at and think of already exists in some area and that area is a different universe I think it's a like it's it's an idea that I feel like I can get behind like can I do the math behind proving it no but there's something about it that I like it just intuitively makes sense it makes you comfortable with the universe that we're in but maybe that is just because that's like what media just always goes through but I do think it's
interesting how the Multiverse light got mentioned in one Marvel film a few years ago and now you have like films based entirely on the Multiverse I don't know how much more research on the Multiverse has been done in that time or if I don't know some writers at Marvel just like saw it somewhere and decided to include it but I wonder if it's getting a more relevant part of science I don't know if it's getting to that like exciting part of physics for example people growing up in the 50s
hearing about a possible like moon landing is like I don't know I don't think we're gonna get any evidence of multiverses but is that where physics is going to like always trying to find something that seems like Out Of Reach I kind of feel like it has to if it's always talking about these theories and is science it doesn't necessarily become more and more complex but you need more multi-disciplinary teams to move science forwards yeah because you can't just look at anything from one
particular angle like even some of the like Material Science work that I've been involved in it's involved like people that understand physics people that do data science people that understand chemistry all of them coming together and people that sort of understand how um radiation Works to look at things yeah so I feel like yeah physics is always going to be sort of pushing that boundary because it's all the maths that it's it's sort of trying to understand how everything fits
together isn't it using maths that's why people I mean you mentioned like a grand unified theory and that's I guess maybe even a bit more particularly because you have the four fundamental forces and three of them just you know they're perfect like they make sense they fit into the standard model um which people know is wrong because of dark matter and dark energy doesn't really fit in but anyways just ignore that jargon yeah yeah anyways so does that obviously the Sun and ball is what
um but because they know that it's not the most perfect model because it doesn't include gravity it doesn't include the full fundamental force and so a lot of people are trying to search for this Theory beyond the standard model that includes everything that works from the standard model with gravity as well because currently it's like separate and when we did a module on it um we did about the standard model for it like nine out of 12 weeks well more than that it was probably like 10 or 11.
and then the final few weeks were on the on the standard model and then it was all these crazy things that could happen and would if this happened and they found this then it would explain all of this and so I think people are always constantly searching to kind of one figure out the unknowns but to figure out what the unknowns can tell us because it's kind of searching for the unknown unknowns in a way I think it's cool but also feels so tiring to me science is about
finding out something and reaching a conclusion and moving forward because that's what you do in school you do an experiment you get your conclusion and then when you get to physics like nothing well the theoretical if it's like yeah we don't really do that we just keep going up with new theories and then trying to figure out ways of testing them how do you measure something that you can't directly interact with yeah well that's what um all of the Paschal experiments I think
they um when there's a new particle that gets theorized they design experiments specifically searching for it and then it's always like I mean I I don't know how particle physics like do it because it's just searching for like this this little bump that just means like the Higgs particle exists and I think that's really cool but I feel like my area physics that I like is like application heavy I wanna do something solve something and then a very quick turnaround I want to see how that's
going to help some thing um I don't know I that's that that's what I realized doing physics I'm like I I really can appreciate the theorists I think they are just crazy uh intelligent um and I like like reading about the theory stuff but as soon as it goes into how do we actually solve this I'm like no I rather see be able to see my Solutions and see how you know what contribution they make so maybe it's just the different types of people just think different parts of
physics are more valuable and more important than others but that's just biases really I think yeah I guess that depends on you your Viewpoint because I would imagine that some of these theories have led to some great discoveries and I was reading about um the whole quantum entanglement thing that is how like um Quantum encryption Works isn't it which is how some data security is done stuff like Quantum encryption people years ago would have thought well that's crazy and it sounds just like some
people say to sound like physicsy but now people are actually trying to get Quantum encryption to work on like a global scale so that when you have your bank details if you encrypt them um using a quantum computer whenever somebody tries to steal them or hack them or take that information it just destroys the information and then it's physically impossible to kind of steal and hack into something because currently I think they do encryption on like secure details so that it takes a supercomputer
100 years to crack it but like the idea is that it's crackable and so now we're moving into using quantum computers to try and have like a key and a lock system if you lock something with a specific key then only with that key can you unlock it and that's that bit Quantum encryption and it suddenly tries to you know break the lock then it breaks and you can't open you know which I think is cool that it's actually getting an application because that's something that's quite theoretical
that's now being found to be useful on the global scale because when you tell that to people they're like my super computer takes 100 years to break into my details no and everyone's like nothing's secure it's obviously good enough for now but I think as well though as like technology advances how much is that time going to be broken down like how good can super computers get before we need to use quantum computers no and I guess if we keep looking into the future this is what I I
find weird about most representations like time travel in films they start hopping around through time and affecting their original timeline but I feel like if if so this is one of the things of string theory where you get so far down the dimensions you can go back and forward in time but I feel like you won't affect the timeline you're originally in because there are all these multiple timelines anyway yeah it's like you were saying that everything is happening anyway I've
never thought about it like that because I always think you know um with time travel films they're always they always say things like you can't change things because you know the Butterfly Effects at the end of the day someone you won't be born you might not be born but I never thought about it as they go back in time to a different universe that was the same at that point yeah that's what I tend to think of I mean I kind of suspend like my normal thinking when I
watch a lot of films that try and incorporate science oh yeah and try and enjoy them honestly wait what is it on um Back to the Future when he goes back and then changes something then he goes back to the future and Everything's changed how does he fix that situation does he go back and undo things yeah so he ends up with sort of like three versions of himself running around doesn't he this is like or is his self from like a previous film doing something okay and
then the other version of himself and then his current I think maybe I'm misremembering him let me have to rewatch Back to the Future but yeah he was basically trying to avoid running into himself wasn't he at every Point yeah because I would say if he went back and then he changed the future surely he could I mean if he could travel through multiverses go to a different Universe where he never changed anything at all because that would theoretically exist it would but
it would make for a very boring movie plot yeah yeah I think they have a plotline like that in Rick and Morty as well there's like a a universe where where they die or they go back in time they die and then the future then buries the past them and then it's just like an area um not an area a scene where um they point at like these holes in the ground and they go that's where we're buried and it's kind of like crazy like thought experiment on how timelines work
which is maybe maybe honestly like you don't need to do a Physics degree you just need to watch Rick and Morty and that's in the future for the time limits and the timelines and then decide for yourself if you think this is actually feasible and then come up with a new Theory yeah maybe more businesses need to work on these shows and then just try and animate all the different theories that are possible and just see what the reaction is from people I think they're
pretty a lot of confused faces but you never know maybe someone will hit on some way of explaining it that is 100 accurate and easy to visualize it's true so you were talking about non-linearity before and some things are and some things aren't can you sort of explain what that means because I think of it as a cause has an effect and that's linear you go from A to B is that what you mean kind of because a course does have an effect but it's like a cause with a slightly different
change has a huge change in that final effect and I get that is essentially what chaos is it's just these like tiny changes in initial conditions that result in huge changes in the final results and non-linearized non-linearity is actually just I think I did a module on it and it's just a really cool concept like you get loads of strange and weird things happening when you have non-linear things happen in the universe which happens you know even just with like
Gene regulation and everything like that that's all non-linear like it happens in biology it's not just like that's what I like about some areas of math and physics is you can see that they happen in actual biological systems and in nature so some people think that non-linearity is a very abstract concept that doesn't have many kind of applications but it's been existing in nature for a while I don't know if I've gone very off topic here uh so I the reason I was asking was because
we were talking about films right um and there's a film on Netflix at the minute called look both ways where someone who is just about to graduate from University shakes a pregnancy test is one timeline where it is positive and she has the child and there's another timeline where it's negative and she goes to pursue a career yeah but they both end up pretty much at the same point at the end it seemed like it didn't really matter what happened in our life she was always destined to have
this career and have a family it didn't really matter how she got there well I guess okay in that context that's a very linear timeline because I would say it's like the the butterfly effect though essentially like not only is when you have like the changes and so I feel like if it was non-linear if it was realistic then she wouldn't be ended up in the same place people always love non-linear stuff in films and now there's a film that's linear I don't know how I feel about that
because I wouldn't yeah I wouldn't say that that would be a talking point I quite liked it it kind of said like it doesn't really matter if you don't do something great first time necessarily you'll get there in the end it's a nice little thought actually maybe they did it for the Post film thoughts and morals where you can get in a bit more confidence and be like yeah it's gonna be okay rather than you make a change and it's everything descends into chaos I wish you exactly what the physics
would say exactly and I find that really disconcerting this idea that this small change can have this this huge effect that could fundamentally change my life as I know it yeah that's how they actually um do like weather modeling sometimes as well is like uh when they have a measurement and they have the forecast at that point they see how different it is and they try and model it to be as close as possible because if there's like a big enough change and difference it means
that you're forecast for three days time is totally different than what it's actually going to be in three days time even when you use a model so that's why I learn if you ever want to know what the forecast is you just have to look the day before because it gets to like six or seven days in advance and because of the differences in the modern what's actually going to happen it just becomes so different it's almost like what's the point of putting a forecast up I think
that brings us back to probabilities as well doesn't it yeah so you always say there's like a 20 chance of rain or a 50 chance of rain and I always think 50 chance is just normal around here that just means it probably won't rain but be prepared anyway it's really interesting how you interpret those probabilities as well because when somebody says 20 tons of rain I always think probably not going to rain and then it does and you say they're wrong but it's only said 100
chance and you're like is that it's raining now is that I don't know because can anything be 100 in the future because there's definitely some times when you look at a forecast and it says 5 p.m 100 chance of rain I feel like we're saying that weather forecasting relies on some really complicated physics and maybe involves a Multiverse everything involves more to us if you try hard enough I feel like we're kind of getting hiddenly distracted and confused by sort of real world things
like forecasting the weather in things that don't really happen but only happen in the movies with some Physics that again also it doesn't really happen but it's just what people think could be possible that's what I'm getting out of this episode but I feel like I still don't quite understand it well enough to sum up very well so do you want to try and conclude this episode Emma sure oh I can say a very cool quote actually it's a family quote and this is hopefully to put everybody at a you know
bit of rest a bit of ease and simply it's if you think you want to send quantum mechanics then you don't understand quantum mechanics that's why I think it's a good place to end it is there's many things that can happen and the Multiverse Theory I think is a really cool Theory to think about and that's why it always gets put in all these films and everything like that which is interesting and cool but when it actually comes to the maps of it that's when things start to get really
confusing you have all these different theories pop up to trying to fit the theory into the mass and so I think dual quantum mechanics physics course and then you'll get that you'll see the maps and then you'll be like yeah and then you'll think about multiverses and then you'll be back to square one again so that's probably the best way to end it fair enough and as Richard Feynman said you'll probably never reach that understanding because it's just it's weird man yeah yeah it really is oh
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