Exploring Time Travel and Its Theories

taz I just got back from the cinema as you know and for the listeners I just went to watch um Bridget Jones Mad About the Boy and I was so excited for it because I don't know if you watched Bridget Jones when you was younger although I don't know if it's like really a film that we should be watching when we're younger I can't really remember them though to be fair but like I do remember them being a bit inappropriate But anyway um I was having a really bad day today and then my friend was like "Do you want to come and watch Bridget Jones?" And I thought "This is perfect." Because what better film to go and watch than Bridget Jones to make you feel better about my own life However I must say it was absolutely awful and I was a bit disappointed with it to be honest because yeah it just wasn't that great and is well I don't want to spoil the film for anyone because it was a bit inappropriate cuz there was like some weird Okay if any of the listeners don't want spoilers just skip forward 30 seconds but her husband dies and then she just starts randomly dating like this 18-year-old So it's like this 50-year-old woman who's like just dating like this 18 I don't know if he was actually 18 but it was just weird It was a weird weird film and it was some time that I wish I could get back in my life to be honest I've heard very mixed mixed feelings about the Bridget Jones films Like some people love it and some people didn't like it But I think I would personally like it cuz the 18year-old in question that you're talking about is Leo Wood Whittle and he is so fit I'm not going to lie Like he did kind of make that film for me I'm not going to lie But anyone kept One Day on Netflix Oh my god That's another thing I wish I could take back And I feel like if you've watched One Day on Netflix do you or do you not regret watching that cuz I was absolutely broken for weeks If you're in any kind of sadness do not watch that series By the way I don't think he's actually 18 in real life Just to like clear that up Me and Taz aren't weirdos We're not like No he's not 18 in real life When you told me about it earlier I was thinking like oh maybe I'll go and watch it But I'm I'm not really down for like sad films I feel like I'm a fragile person I also feel like I'm having a fragile week I'm a fragile person this week So I definitely ain't starting that series this week Like it ain't happen I didn't start it this week But it was it broke me but it was so good So it's hard to say If you've watched One Day and you're listening let us know in the comments because I would love to know what people think and whether they would watch it willingly watch it Yeah If they knew the outcome Okay Yeah Let Let me know cuz then I'll I'll take that on board and decide if I'm going to watch it But anyway so we've mentioned that we want to get our time back or sometimes we regret doing certain things with our time And today we are actually touching on that topic Well we're not just touching on it We're doing a whole episode on it because in today's episode we are covering the conspiracy theory of whether or not time travel is possible And I'm very excited for this So let's get into today's episode This is Debunked by the SoCulture podcast hosted by Liv and Taz Two girls exploring the world of science and tech unfiltered This season we're separating facts from fiction as we dive into the world's most controversial conspiracy theories by seeing if science can prove or disprove them And of course we are still serving up the laboratory because the STEM world is messier than you think Don't forget all opinions are our own and all of our listener stories are alleged Let's get into this week's episode of Debunked [Music] April 23rd 2006 It was a normal afternoon in Kiev Ukraine when a young man in his early 20ies appeared in the city center He was staring wideeyed at his surroundings Witnesses would later describe him as looking completely lost as if he had just woken up in a world that made no sense He was dressed in perfectly pressed but outdated clothes and he clutched an old-fashioned camera in his hands His behavior was strange like nervous and hesitant and he approached two police officers asking for help Excuse me he asked Can you tell me how to get to Pesha Street the officers exchanged confused looks The name sounded vaguely familiar but there was a problem Pesha Street didn't exist anymore So now growing suspicious they asked for his identification And that's when things got really strange Sergey Panamareno's official documents were authentic but they were issued by a government that hadn't existed for 15 years They were also marked with the seal of the Soviet Union a country that had dissolved in 1991 And the biggest shock his birth date 1932 What if this man was telling the truth he should have been 74 years old but the person standing before them was no older than 25 And at first the officers assumed that he was either lying or mentally unstable So they decided to take him in for questioning And that's when they noticed something else his camera a vintage model well preserved but decades out of date And when they asked him about it Sergey insisted that he had just used it earlier that day So skeptical the police sent the film inside to be developed and what they found was impossible So the images showed Kiev not in 2006 but in the 1950s The cars the buildings even the street signs matched historical records perfectly Sergey himself was even in the pictures wearing the exact same clothes that he had on that day And by this point the authorities were at a complete loss If this was an elaborate prank it was flawless And if it was a delusion it was a highly detailed one So they placed Sergey under psychiatric observation while they figured out what to do next But they never got the chance because just 2 days later Sergey vanished without a trace And there was no record of his escape no security footage of him leaving It was as if he had simply stepped out of time This sounds like something out of a sci-fi novel and maybe it is But here's the thing This is not the only story like it Throughout history people have reported strange time slips moments where the past and the present seem to blur together For example there's the famous story of the two Oxford academics who claimed they walked straight into 18th century Versailles And these aren't just ghost stories because when you start looking at how time actually works through physics relativity and quantum mechanics one thing becomes clear Time is not as simple as it seems Oh my god I'm excited for this episode because like I'm we're both like quite sci-fi girly so I'm like "Yes please say it's real." I feel like this is so controversial to like all the conspiracy theories that we've touched on where I've been like no you've been hard against it whereas this one I'm like I want it to be real cuz that is so cool Okay Well there are some aspects that are definitely intriguing I will say that So let's get into it So if time travel is real then the most important question isn't how it's why Why does time seem to move in one direction like why can't we remember the past but not the future and if time can be manipulated then what does that actually even mean yeah 100% And if we're talking about time travel we actually need to understand what time is first right yeah Exactly So scientifically time is defined as the progression of events from the past to the present and into the future But that's just how we experience it In physics time is treated as a dimension just like length width and height If space has three dimensions then time is the fourth And you'll often hear people refer to time as the fourth dimension But here's where things get weird See unlike space where you can obviously move freely in any direction Time only moves forward So you can step left or right You can move forward or backward but you can't step into yesterday right yeah Oh that makes so much sense So why can't we move through time like we move through space yeah So the best way to understand why time only moves forward is through the concept of entropy So entropy is essentially a measure of disorder And the second law of thermodynamics tells us that in a closed system like the universe entropy always increases So in other words things naturally move from order to chaos over time So we can think of a sand castle for example When you first build a sand castle the grains of sand are all arranged in a really specific way They're structured and they're organized into your little sand castle and that is low entropy So it's a highly ordered state But if we take that same sand castle and we pop it in the Sahara desert or we leave it out in the wind for example over time this sand castle is going to collapse The grains will get scattered and eventually all you will have is a random pile of sand and that is high entropy or more disorder Here is where time comes in So entropy is the reason that we can actually tell the difference between the past and the future So think about it Why do we remember yesterday but not tomorrow it's because the past had lower entropy and the future has higher entropy And the increase of entropy is exactly what gives time its direction And the entire universe started in a low entropy state highly structured and full of energy after the big bang And over billions of years it has been getting more and more disordered So in a way time doesn't actually move forward on its own But what we experience as the passage of time is really just the slow inevitable increase of entropy throughout the universe Liv I learned about this at school and I feel like you just summed it up in the best way that I've understood that so well compared to like three years of like GCSE physics or however long you do physics for So well done That was a really good summary So I guess to test my knowledge if entropy could somehow stop increasing would based on what you said would time stop too So that is the idea So some theories suggest that if entropy could be reversed time could also be reversed But here's the catch According to everything we know about physics entropy actually cannot decrease overall which means that time keeps pushing forward So no matter what we do like I said things naturally move from order to disorder and time moves with them So that's why we can't just step back into the past like we move through space Yeah Exactly So the past was a lower entropy state and the universe doesn't just go backward like that because time flows in one direction because entropy does and entropy cannot like it's always increasing rather than decreasing Now another really important point about time is that it doesn't float at a fixed rate for all observers It stretches and it shrinks depending on two things speed and gravity And we have covered some of these topics in previous episodes but let's go over them So this is all to do with Einstein and his theory of relativity Now there are actually two versions of his theory Like I just said we've got special relativity that tells us that time slows down when you're moving fast And this is called velocitybased time dilation And then general relativity tells us that gravity also affects time So stronger gravity makes time run slower And this is called gravitational time dilation which like I said is a concept that we explained in our interstellar episode in season 3 But a good way to think about the speed part is with movement So imagine you are walking inside a train that's moving at 60 mph If you walk forward or you're walking through the train at 3 miles hour someone watching you from inside the train is going to see you as moving at 3 miles hour right but someone outside of the train watching the train go by sees you moving at 63 mph So your speed is added to the trains And time works the same way So if you're moving really fast time will literally slow down for you compared to someone standing still And scientists proved this in 1971 with something called the Hili Keiting experiment So they took two identical atomic clocks which are basically super precise clocks like literally down to billionth of a second So one of the clocks stayed on the ground and the other was flown around the world on a plane But when the plane landed the airborne clock was actually slightly behind the one on the ground I actually always think this because obviously living in Australia and you like you go over obviously it's not the same thing really but you go over different time zones and when I always go back to the UK I would have left Australia like I don't know 7:00 p.m and I go go to the UK and I land in the same day and I'm like this is madness but obviously it's not it's not the same concept but I do just kind of relate it to like time travel in a way but anyway so time actually slowed down for the clock on the plane that's what you're saying yes and this isn't just theory it's actually something that we have to account for every single day so astronauts on the international space station which is moving at around 20,000 km hour actually experience time slightly slower than we do here on Earth So if you spent 6 months up there on the International Space Station you would actually return about 0.02 seconds younger than if you had stayed here on Earth So obviously it's barely noticeable but what if you wanted to go further so we have already established the faster you move the slower time runs for you Now if you traveled at 99% the speed of light time would stretch to the extreme while you would experience just one year entire centuries could pass for the rest of the world here back on Earth So the idea is that you could step onto a spaceship accelerate close to light speed and leap thousands maybe even millions of years into the future But there's a catch You could go forward but the universe is designed so you could literally never come back And Professor Brian Cox has spoken about this Taz we know you love Brian Cox I'm so glad you said that cuz I was about to say "Love him." You got there before me I literally love him And actually I saw him do a little clip of him talking about this and it's what motivated me to do like want to do this episode cuz I was like "Oh my god it sounds so interesting." So yeah he's spoken about this So traveling forward in time is scientifically possible proven by Einstein's special relativity as we've just spoke about But the universe is designed so that time is literally a one-way road So if you leave the world you knew will vanish behind you It will age faster and faster until it's literally unrecognizable You could step into the distant future but there's no physics no equation no loophole that actually lets you return and tell anyone what you saw because they would literally all be dead by the time that you came back which I just think is a really simple but cool concept is you could time travel thousands of years into the future but by the time you got back everyone would be dead And I just thought that was a really cool and interesting concept that essentially the universe is designed in a way that like you could never you can go into the future but you can never tell anyone what you found Yeah that is crazy But speed isn't the only thing that affects time Obviously we spoke about this before but gravity does too And this is called gravitational time dilation And black holes are the best example So think of spacetime like a stretchy fabric When you put something massive on it like a planet it will create a dip in the fabric of spaceime The bigger the object the deeper the dip And black holes are obviously like massive bowling balls slamming into a trampoline So they literally make space time sink Now as we said the stronger the gravitational pull the deeper that dip and the slower time moves for anything inside it Essentially if you spent just a few days near a super massive black hole you would return to Earth millions of years later So we've covered how time travel into the future is scientifically possible even proven Like it's literally been proven Okay so talking about the conspiracy theory of time travel scientifically absolutely you can go into the future We know this But going backward in time that is where things get messy Not just technologically but also logically So it's not just that we don't have the right kind of machine or the tech to do this but there are actual fundamental problems with how cause and effect works So if traveling backward in time were possible it would actually lead to paradoxes which are basically situations where logic and reality break down And one of the most famous examples which everyone's probably heard of before is the grandfather paradox So imagine you travel back in time and accidentally prevent your grandfather from meeting your grandmother Now if that happens obviously your parents wouldn't have been born which means you wouldn't have been born But if you were never born then how did you time travel in the first place so that's the paradox right it creates a loop that contradicts itself So time travel especially going backwards actually kind of breaks reality So if time travel to the past creates these contradictions does that mean that it's completely impossible not necessarily So some physicists argue that paradoxes don't actually happen at all because time in a way protects itself And one of the most well-known solutions is the Novikov self-consistency principle proposed by physicist Igore Novikov So this principle suggests that time travel is possible but only in ways that don't create contradictions So in other words if you were to travel back in time you could never change history in a way that prevents you from actually making the trip in the first place So the timeline is self-consistent Causality is preserved no matter what And this idea is actually rooted in Einstein's general theory of relativity specifically in something called closed timelike curves or otherwise known as CTC's And these are solutions to Einstein's field equations that theoretically allow for loops in spaceime Now if such loops exist then time travel into the past isn't just possible but it's actually mathematically allowed But Novikov argued that even if these loops exist physics would enforce consistency Meaning that everything that happens inside the loop must have already been accounted for in history and therefore no paradoxes are allowed So to break that down a little bit further let's say that you decide to go back in time and stop your grandfather from meeting your grandmother According to Novikov's principle something will always prevent you from changing history in a way that creates a paradox So for example like maybe you would get delayed maybe your time machine quote unquote would malfunction or maybe without realizing it you're actually the reason that they met in the first place So no matter what you do history remains self-consistent and you can interact with the past but you cannot rewrite it And so any action you take was actually always part of history which led to the very events that you set out to change And again this is not just a theoretical idea It has actually been tested in force experiments like the time traveling message paradox So imagine that you are sat at your desk when out of nowhere this random note appears in front of you and it reads "Don't forget to email your professor at 3 p.m So you check the time It's 2:55 p.m and you're confused but you're curious So you decide to follow the notes instructions and you send the email at exactly 3 p.m Now later as an experiment you write the exact same note and send it back in time to 2:50 p.m So you're looking at me so blankly So think about what just happened right the note exists because you found it and you decided to send it back in time but you only need to send it back because you had already received it So there was actually never a point when someone originally wrote it It simply exists as part of a closed time loop Does that make sense right Yeah Like it's just it's forever looping in time because yeah wrote it originally Yeah Well there's no original It's just forever looping So this is how Noikov's principle works So events inside a time loop do not create contradictions Instead they are self-consistent So no matter what the timeline will arrange itself so that everything will line up logically And if you try to prevent something from happening and if you try to change history somehow the universe will ensure that you still end up playing your role in the event exactly as it was always meant to happen And so this is the idea that the past is not rewritten It's just reinforced Can I just say can I just like jump in here that like I find with physics is that it's so theoryheavy like this principle it could be a reality but like surely there's absolutely no way of proving that yeah um okay so I'll tell you about something related to that because this was my question I was like okay well we can't just come up with a theory and be like okay here's a theory and like this is it and I'm just going to explain away I'm just going to explain time travel now just with this random idea that I come up with So I also thought the same thing So in 2019 researchers at IBM conducted a quantum time travel simulation using a quantum computer Now they introduced paradoxical conditions which is like sending information backwards in time in a way that would erase its own existence But every time they did this the system naturally adjusted itself to avoid contradiction And the quantum states always corrected in a way that maintained self-consistency as if reality has built-in error correction to prevent paradoxes which is interesting if you listen to the simulation episode But essentially what I find this demonstrated is that it does happen but I don't necessarily know if they understand like how and why it happens I mean this is kind of where I drew simulation theory isn't it it's giving simulation theory 100% But this is kind of where I drew my line of like this is how much I'm going to understand Do you know what I mean i was like okay I understand this much and I'm drawing the line there So if any of the listeners are interested in reading more about this like please feel free because I'm sure there probably is some people working on like the underlying maths and physics of this Now on that note before we get deeper into how this connects to time travel I have to be honest As I said I really struggled with researching this episode I'm not going to lie Like I obviously love science but physics is really not my strong suit And trying to wrap my head around relativity closed time like curves and quantum mechanics let me tell you my brain felt like it was overheating And that is where Odeik today's episode sponsor actually saved me So instead of trying to read through pages and pages of dense physics papers I used to listen to them instead It takes complex academic research and turns it into structured audio so you can actually understand highle concepts without spending hours decoding technical jargon and reading over the same sentence a million times Because that's my issue is like when I'm reading something that's complicated I will read this same sentence over and over again and it's like my eyes are reading it but my brain is not reading it But if I'm listening to it it just goes into my brain Like it's just straight in there Yeah I'm 100% like that Like I will listen to an audio book and read the book at the same time because you it's like fully immersive experience And you could obviously do that with Demic as well So if you're a PhD student a researcher or someone who just loves science but really struggles with the dense academic writing which I 100% do or demic is actually a gamecher cuz you can listen to the papers whilst commuting walking or in Liv's case while pacing around her kitchen trying to understand these time paradoxes They also have dyslexia friendly fonts and note-taking features as well making it one of the best tools out there for staying on top of research And Odmic offers a 7-day free trial So if you want to save time and actually absorb the research you need we will add the link to Odmic in today's video or episode description So make sure you head there to try it out And we also have a discount code for you guys that will pop on screen now But for now let's get back to time travel Now we've spoken about Novikov's theory but not all physicists agree with this approach Some argue that self-consistency is just way too restrictive and that time travel if possible would not be limited by an unchangeable timeline So instead they propose an alternative one that allows for changes to the past without violating causality And this brings us to the many worlds interpretation of quantum mechanics Unlike Novikov's principle which assumes a single self-consistent timeline the many worlds interpretation suggests that every possible outcome of an event actually happens but in separate parallel universes You knew we were going to talk about parallel universes on this episode cuz how could we not now this idea stems from one of the most famous experiments in quantum mechanics I'm so sorry but we're back with the double slit experiment If you listen to the simulation episode you heard about the double slit experiment I gave a very detailed explanation of that experiment in that episode So if you want a detailed explanation then make sure you listen to the simulation episode And you should just listen to it anyway because I'm biased but I think it was the best episode on this series because well I'm not saying that oh my episode was better than yours I just offended it was really good I just meant that like I enjoyed the science of that episode so much So the idea of the experiment is that you have a barrier in between essentially like you and a wall and you're firing electrons or photons at this barrier Now there are two holes in the barrier and basically scientists were measuring how the electrons or the photons pass through these two barriers and what kind of pattern they produced on the wall behind Now the double slit experiment revealed that particles like electrons or photons do not behave like balls with fixed paths Instead they acted like waves existing in multiple states once So when an electron was sent through two slits it didn't just go through one or the other It actually went through both of them simultaneously creating what's known as an interference pattern But the moment we measure or observe the electron it chooses a single path as if reality is only decided when we look at it Now some physicists take this a step further and suggest that reality isn't fixed until it's observed meaning every possible path still exists somewhere in another universe Applying this to time travel the many worlds interpretation suggests that if someone were to travel back in time and alter the past they wouldn't change their own timeline but instead they would create an entirely new branch a separate universe where their changes took effect The original timeline remains unchanged while the traveler finds themselves in a parallel reality This would mean that time travel doesn't break causality because rather than altering an existing history it simply shifts the traveler into a different version of events And this raises an unsettling question If time travel has ever happened we would never know because our timeline would remain untouched And if that's the case is it really time travel or just an extremely complex way of moving between parallel worlds i actually feel like I want to align myself with the parallel universe theory because I feel like you know we touched on this on simulation theory about um Mandela effects and loads of people say that we entered a different like a parallel universe when as a result of these like Mandela effects So like there's no evidence of it in our history but people still remember it because like they've shifted into a parallel universe That's like my conspiracy theorist's hat on but and obviously going back to Brian Cox I've seen him do talks before and he talks about parallel universes So he I feel like he backs this theory as well So if he backs it I back it If Brian Cox backs it we back it So culture backs it literally So okay just to kind of sum up time travel into the future absolutely possible in terms of like what is kind of allowed by physics and gravity and speed and all that sort of stuff Absolutely possible But time travel into the past seems kind of like hard to say Yeah that's what it looks like And that's before we even talk about the biggest problem right which is like even if time travel to the past is possible like how would you even do it oh my god is this the part where we talk about wormholes yes we love a wormhole on this podcast So the idea of wormholes comes straight from Einstein's equations So in 1935 Einstein and physicist Nathan Rosen discovered that mathematically spacetime could in theory fold over itself and create a tunnel between two distant points And these actually became known as Einstein Rosen bridges or what we now call wormholes So we've said this analogy before but you can imagine spacetime as a two-dimensional sheet of paper Now if you want to travel from one side to the other you'd normally have to cross the entire sheet But if you fold the paper and punch a hole through it you could jump instantly from one point to another And that is the basic idea behind a wormhole It's essentially a cosmic shortcut through spaceime Now if wormholes exist and let's just say that like there is actually no evidence for wormholes So let's just put that out there right now Again we spoke about that on the Interstellar episode But if wormholes do exist and if one mouth of the wormhole is moving at relativistic speeds or placed in a strong gravitational field time dilation would mean that the two ends of the wormhole experience time at different rates right this means that a traveler stepping into one end could theoretically exit at a different point in time So like in other words a wormhole might not just be a portal through space but it is actually a time machine But and this is a big butt there is a huge problem because we have zero evidence that stable traversible wormholes actually exist And even if they did keeping them open long enough to travel through would require something that we don't actually know how to produce yet Negative energy What is that so negative energy is a bizarre concept that comes from quantum mechanics Just like every everything that comes from quantum mechanics is bizarre I feel But under certain conditions quantum fluctuations can create regions of space with less than zero energy Essentially it's a vacuum that exerts repulsive gravity And this kind of energy could in theory prevent a wormhole from collapsing which would keep it stable for long enough to actually pass through And some physicists suggest that the Casemir effect which involves tiny quantum fluctuations between two closely spaced plates might be evidence that negative energy is actually real So without negative energy any natural wormhole that formed would actually just collapse instantly So even if one did exist the gravitational forces inside would likely actually just rip apart anything trying to actually pass through it So while they remain a fascinating theoretical possibility there's actually no real path to making them work as time machines at least not yet But I feel like we kind of have something similar to that in Black Holes right because going back to our good friend Brian Cox he definitely mentioned um like warped time If you were to like approach a black hole what's is that is that related to that in any way mhm Yeah And again I think we did speak about this a little bit on the Interstellar episode but there is the idea of using rotating black holes And some physicists speculate that if a black hole is spinning fast enough it might actually create a stable possible wormhole inside Meaning that yes you could enter one side and emerge somewhere else But again this is purely theoretical And even if this did exist like a wormhole inside a spinning black hole like even if it existed we would literally have no clue how to navigate it without being crushed So the short answer is no We can't use wormholes or black holes for time travels At least not yet But the long answer is maybe we could if we ever figure out how to generate and control negative energy or if new physics reveals stable traversible wormholes I mean the idea isn't totally off the table but for now unless you're willing to take a one-way trip into the distant future by hovering near a black hole time travel remains stuck in theory not reality Oh I'm kind of sad about that I mean same because I'd love to go back in time and change a few things you know i always feel like No regrets No regrets I wouldn't want to No regrets No regrets Yeah So we've talked about time travel but let's zoom out like way out So the universe itself has a clock and that clock started ticking 13.8 billion years ago with the Big Bang Before that as far as we can tell time literally didn't exist But if time had a beginning does that mean it could also have an end well right now physicists think there are three main ways the universe could end and each one has massive implications for time itself So first up we have the big crunch theory And this is the idea that the universe will eventually collapse back in on itself essentially reversing the big bang And if this happens time itself would literally end as the universe reaches a singularity just like the one that birthed it And some theories even suggest that if the universe collapses in a big crunch another big bang might actually follow essentially restarting time in an endless cycle And if that's true then maybe time is just an infinite loop playing over and over So like is time itself a closed loop i don't know I just thought that was an interesting concept But having said that right now that isn't the leading theory And that brings us on to the big freeze because right now the universe is expanding and galaxies are moving far away from each other Space itself is also stretching But what's weird is that this expansion is also accelerating So instead of slowing down due to gravity something is actually pushing the universe outward like faster and faster And that something is dark energy And if this keeps going we'll get what's called the big freeze So here is what happens Essentially as galaxies spread apart stars will run out of fuel and burn out Black holes will slowly evaporate through Hawin radiation and eventually all that's left will be a cold dark lifeless universe Well that's depressing And at this point time wouldn't stop exactly but it would lose all meaning And again we're here back with the philosophical questions But if time is defined by change by events happening if nothing is happening there's no movement no energy and no interactions then is time even moving is time even a thing anymore and then this is our last idea What if dark energy energy doesn't just keep the universe expanding but it actually grows stronger over time now this is the idea behind the big rip and it is terrifying So right now dark energy is pushing galaxies apart at an accelerating rate but in a big rip scenario it wouldn't stop there Instead it would continue to strengthen it until it's not just expanding space but it's literally tearing apart everything inside it Eventually it would go even deeper ripping apart molecules atoms and then even the fundamental particles that make up reality And finally dark energy would unravel the very fabric of spaceime itself And if this happens time wouldn't just stop but it would cease to exist altogether So if time has a beginning and an end can we ever truly time travel or are we just passengers on like a one-way journey through time with literally no control in a big crunch scenario maybe time like I said loops back on itself meaning past and future could just be different cycles of the same repeating universe which is scary And if that's true perhaps time travel isn't about jumping to another moment but instead it's waiting for the cycle to restart And in a big freeze time might just stretch out forever but eventually it just literally wouldn't matter anymore because there's nothing left to experience it And in a big rip time wouldn't just stop It would literally be ripped out of existence And there would be nothing left to even travel through So right now we do not know which of these futures will happen But one thing is clear Time is not something we just move through It's something that could one day end And that might just be the biggest time travel paradox of all Mic drop Oh my god I've come away thinking like time travel is going forward in time absolutely possible backwards in time there's no real evidence necessarily that it would be possible that's how I feel anyway I don't know how you feel live I feel the same but I'm also a fan of the parallel words the many worlds interpretation I'm a fan of that and I think I'd love to dive a little bit more into the parallel universes So we'll definitely have to cover that in like a future episode probably in a different series But yeah for the listeners of course as we do every single week we will pop a poll on our Instagram So you'll have to come over and let us know what you think of the conspiracy theory around time travel I mean your answers will probably be a little bit more nuanced than just like a yes or no but come over and get involved anyway Um so with that that rounds off the science for today's episode And I think we have a listener story that we really need to get into So let's get into the laboratory section of today's episode [Music] Okay we've had a listener write in and the subject line is betrayed by my lab bestie So let's get into the email In 2023 I began my masters in another university across the country I ended up joining a lab who took three master students in one go And it was exciting because we were all girls in STEM and all the same age And one would have assumed that we would have been so close given the proximity and common interests However that is not what happened One of the girls who was at this uni since undergrad was extremely insecure in herself and her abilities and kind of felt threatened by me since I wasn't like stupid I guess However it wasn't just a little jealousy She [ __ ] talked me to the entire department before anyone even got to know me And it was actually so bad And I felt so lonely It was such a horrible experience And I felt anything I did was just not good enough Even after speaking to her numerous times it never got better And the only thing that made it better was honestly completely removing myself and finishing my lab work earlier and just working from home And even though I love my project and supervisor I never considered staying for my PhD since she's also staying and I cannot go through that for my mental health Toxic lab culture is honestly so unhealthy and I honestly hate it Oh that is a lot That is a lot I feel like we've done so many stories recently about Sorry my cat's just coming to join us We've done so many stories recently about toxic labs toxic academic culture and I honestly feel like this is just going to be a running theme on the podcast for as long as we're doing these liberties like it is going to be a running theme because it's just so so common for me Honestly I can't lie The most disappointing thing about this story is the fact that there was like three of you girls You all started out together and you didn't become besties I don't know why I feel like that is the most painful part of this story because you know women in STEM we should be supporting each other and like uplifting each other M yeah I do definitely think like being in science is like weirdly competitive Like some other people are just so competitive about what they want to achieve and it's like oh my god because do you remember the my friend stole my research idea laboratory from last season where like her friend literally stole her whole idea Not only are we not like supporting and uplifting each other but we're actually backstabbing each other because this this girl even said that the other girl was like [ __ ] talking her to the whole department Yeah Literally I'm like it's hard enough being women in STEM Like we don't need to pitch against each other Do you know what I mean like doesn't make literally any sense I feel like if people worked together more in the labs you'd actually get so much more done like I went from a very non collaborative lab and it was literally just me doing stuff and then I I've since moved to a lab that is quite collaborative and everybody's kind of willing to help out and you obviously are then part of so many more projects because you help other people they help you and it's like you kind of expand your own experience and also if you help enough then you get your names on more So it's just like come on like let's just all work together and then it builds up like your experience and your academic CV because you got more papers published and stuff Also the science science world is like so heavy on networking and collaborations Like in academia it's really good to have these like networking opportunities because if you meet people that that's how you create new projects and apply for new grants like if you're just stuck within your own sort of institute then those opportunities never come about So if you're this person who's like shit-talking someone else in the lab then no one's gonna want to collaborate with you Just saying 100% 100% And like what are you even what is she even saying about you because what what have you even got to say about cuz she said she works from home So I'm assuming they're like not even really in the lab I'm assuming they're by informatics But everything you said still stands cuz obviously I was fully computational and like my supervisor was very good at encouraging collaborations Did she would go in early to finish lab work or she finished lab work true but still I just don't what is she even possibly saying about you that to the point where she has to go and talk to other people in the department do you know what I mean I get maybe talking to people in your office and having a little gossip I mean personally me I wouldn't do it like I definitely don't gossip about like other students and people on my level yeah maybe in my office we have a little gossip about the PIs can't I yeah exactly I mean it's got to be done but like we're definitely not like gossiping about like other people on our level or like below us That's weird No talking either Like Yeah But one thing I will say is like I'm so glad that she decided not to stay in this lab cuz I think so many people just think okay it's so easy if I just stay in this lab I've got an easy PhD position like lined up for me but I'm so glad that you didn't commit to like another three to seven years depending on like where you're from Cuz like if you're in the US that's like 7 years right to do a PhD But if you're in the UK 3 years But either way I'm still so happy that you decided to just get out of there and not commit to like another 3 years Yeah But she didn't say that she was going to do a PhD somewhere else So I hope it hasn't tainted your entire view of it Like fair enough don't do your PhD there but don't let it put you off doing a PhD Like don't let this girl get one up with you girl kick you out of academia because she's not nice Like don't let her win babes No I fully agree Like you can leave academia after you've done the PhD because I'm fully here for that But I say that I literally work in academia But um yeah No I agree I do want to know Yeah I wonder what is what is she doing now m I'd love to hear from some people in industry as well cuz I reckon some rounchy gossip goes down in industry Yeah 100% Do you know what I mean cuz I don't think we've ever had any like industry listeners right in like it's always academia and like we always get the topic I think that says a lot more about academia Yeah this is true But I feel like No I'm I'm I think there's some good gossip that goes on in industry So like yeah if you're listening and you're someone who parties as well No we've spoke about this before The work Christmas parties are crazy Some random stuff goes down at work Christmas parties So if you are someone who works in industry and you have any of that gossip to share with us maybe it is one of your crazy Christmas work party stories or maybe I don't know just like some random office gossip let us know because we need to we need to start figuring out and understanding what gossip goes on in industry compared to academia You can find the anonymous link in today's episode description or video description if you're watching on YouTube or you can just email us at [email protected] whatever you prefer But with that that rounds off episode 5 of Debunked So we will see you guys in next week's episode where Taz what are we going to be covering yeah we're gonna go back to the virus and COVID theme and we're going to be talking all about microchips and vaccines But for now that is the end of episode 5 And we will see you guys in next week's episode Wendy say goodbye Hey

taz I just got back from the cinema as you know and for the listeners I just went to watch um Bridget Jones Mad About the Boy and I was so excited for it because I don't know if you watched Bridget Jones when you was younger although I don't know if it's like really a film that we should be watching when we're younger I can't really remember them though to be fair but like I do remember them being a bit inappropriate But anyway um I was having a really bad day today and then my friend was like "Do you want to come and watch Bridget Jones?" And I thought "This is perfect." Because what better film to go and watch than Bridget Jones to make you feel better about my own life However I must say it was absolutely awful and I was a bit disappointed with it to be honest because yeah it just wasn't that great and is well I don't want to spoil the film for anyone because it was a bit inappropriate cuz there was like some weird Okay if any of the listeners don't want spoilers just skip forward 30 seconds but her husband dies and then she just starts randomly dating like this 18-year-old So it's like this 50-year-old woman who's like just dating like this 18 I don't know if he was actually 18 but it was just weird It was a weird weird film and it was some time that I wish I could get back in my life to be honest I've heard very mixed mixed feelings about the Bridget Jones films Like some people love it and some people didn't like it But I think I would personally like it cuz the 18year-old in question that you're talking about is Leo Wood Whittle and he is so fit I'm not going to lie Like he did kind of make that film for me I'm not going to lie But anyone kept One Day on Netflix Oh my god That's another thing I wish I could take back And I feel like if you've watched One Day on Netflix do you or do you not regret watching that cuz I was absolutely broken for weeks If you're in any kind of sadness do not watch that series By the way I don't think he's actually 18 in real life Just to like clear that up Me and Taz aren't weirdos We're not like No he's not 18 in real life When you told me about it earlier I was thinking like oh maybe I'll go and watch it But I'm I'm not really down for like sad films I feel like I'm a fragile person I also feel like I'm having a fragile week I'm a fragile person this week So I definitely ain't starting that series this week Like it ain't happen I didn't start it this week But it was it broke me but it was so good So it's hard to say If you've watched One Day and you're listening let us know in the comments because I would love to know what people think and whether they would watch it willingly watch it Yeah If they knew the outcome Okay Yeah Let Let me know cuz then I'll I'll take that on board and decide if I'm going to watch it But anyway so we've mentioned that we want to get our time back or sometimes we regret doing certain things with our time And today we are actually touching on that topic Well we're not just touching on it We're doing a whole episode on it because in today's episode we are covering the conspiracy theory of whether or not time travel is possible And I'm very excited for this So let's get into today's episode This is Debunked by the SoCulture podcast hosted by Liv and Taz Two girls exploring the world of science and tech unfiltered This season we're separating facts from fiction as we dive into the world's most controversial conspiracy theories by seeing if science can prove or disprove them And of course we are still serving up the laboratory because the STEM world is messier than you think Don't forget all opinions are our own and all of our listener stories are alleged Let's get into this week's episode of Debunked [Music] April 23rd 2006 It was a normal afternoon in Kiev Ukraine when a young man in his early 20ies appeared in the city center He was staring wideeyed at his surroundings Witnesses would later describe him as looking completely lost as if he had just woken up in a world that made no sense He was dressed in perfectly pressed but outdated clothes and he clutched an old-fashioned camera in his hands His behavior was strange like nervous and hesitant and he approached two police officers asking for help Excuse me he asked Can you tell me how to get to Pesha Street the officers exchanged confused looks The name sounded vaguely familiar but there was a problem Pesha Street didn't exist anymore So now growing suspicious they asked for his identification And that's when things got really strange Sergey Panamareno's official documents were authentic but they were issued by a government that hadn't existed for 15 years They were also marked with the seal of the Soviet Union a country that had dissolved in 1991 And the biggest shock his birth date 1932 What if this man was telling the truth he should have been 74 years old but the person standing before them was no older than 25 And at first the officers assumed that he was either lying or mentally unstable So they decided to take him in for questioning And that's when they noticed something else his camera a vintage model well preserved but decades out of date And when they asked him about it Sergey insisted that he had just used it earlier that day So skeptical the police sent the film inside to be developed and what they found was impossible So the images showed Kiev not in 2006 but in the 1950s The cars the buildings even the street signs matched historical records perfectly Sergey himself was even in the pictures wearing the exact same clothes that he had on that day And by this point the authorities were at a complete loss If this was an elaborate prank it was flawless And if it was a delusion it was a highly detailed one So they placed Sergey under psychiatric observation while they figured out what to do next But they never got the chance because just 2 days later Sergey vanished without a trace And there was no record of his escape no security footage of him leaving It was as if he had simply stepped out of time This sounds like something out of a sci-fi novel and maybe it is But here's the thing This is not the only story like it Throughout history people have reported strange time slips moments where the past and the present seem to blur together For example there's the famous story of the two Oxford academics who claimed they walked straight into 18th century Versailles And these aren't just ghost stories because when you start looking at how time actually works through physics relativity and quantum mechanics one thing becomes clear Time is not as simple as it seems Oh my god I'm excited for this episode because like I'm we're both like quite sci-fi girly so I'm like "Yes please say it's real." I feel like this is so controversial to like all the conspiracy theories that we've touched on where I've been like no you've been hard against it whereas this one I'm like I want it to be real cuz that is so cool Okay Well there are some aspects that are definitely intriguing I will say that So let's get into it So if time travel is real then the most important question isn't how it's why Why does time seem to move in one direction like why can't we remember the past but not the future and if time can be manipulated then what does that actually even mean yeah 100% And if we're talking about time travel we actually need to understand what time is first right yeah Exactly So scientifically time is defined as the progression of events from the past to the present and into the future But that's just how we experience it In physics time is treated as a dimension just like length width and height If space has three dimensions then time is the fourth And you'll often hear people refer to time as the fourth dimension But here's where things get weird See unlike space where you can obviously move freely in any direction Time only moves forward So you can step left or right You can move forward or backward but you can't step into yesterday right yeah Oh that makes so much sense So why can't we move through time like we move through space yeah So the best way to understand why time only moves forward is through the concept of entropy So entropy is essentially a measure of disorder And the second law of thermodynamics tells us that in a closed system like the universe entropy always increases So in other words things naturally move from order to chaos over time So we can think of a sand castle for example When you first build a sand castle the grains of sand are all arranged in a really specific way They're structured and they're organized into your little sand castle and that is low entropy So it's a highly ordered state But if we take that same sand castle and we pop it in the Sahara desert or we leave it out in the wind for example over time this sand castle is going to collapse The grains will get scattered and eventually all you will have is a random pile of sand and that is high entropy or more disorder Here is where time comes in So entropy is the reason that we can actually tell the difference between the past and the future So think about it Why do we remember yesterday but not tomorrow it's because the past had lower entropy and the future has higher entropy And the increase of entropy is exactly what gives time its direction And the entire universe started in a low entropy state highly structured and full of energy after the big bang And over billions of years it has been getting more and more disordered So in a way time doesn't actually move forward on its own But what we experience as the passage of time is really just the slow inevitable increase of entropy throughout the universe Liv I learned about this at school and I feel like you just summed it up in the best way that I've understood that so well compared to like three years of like GCSE physics or however long you do physics for So well done That was a really good summary So I guess to test my knowledge if entropy could somehow stop increasing would based on what you said would time stop too So that is the idea So some theories suggest that if entropy could be reversed time could also be reversed But here's the catch According to everything we know about physics entropy actually cannot decrease overall which means that time keeps pushing forward So no matter what we do like I said things naturally move from order to disorder and time moves with them So that's why we can't just step back into the past like we move through space Yeah Exactly So the past was a lower entropy state and the universe doesn't just go backward like that because time flows in one direction because entropy does and entropy cannot like it's always increasing rather than decreasing Now another really important point about time is that it doesn't float at a fixed rate for all observers It stretches and it shrinks depending on two things speed and gravity And we have covered some of these topics in previous episodes but let's go over them So this is all to do with Einstein and his theory of relativity Now there are actually two versions of his theory Like I just said we've got special relativity that tells us that time slows down when you're moving fast And this is called velocitybased time dilation And then general relativity tells us that gravity also affects time So stronger gravity makes time run slower And this is called gravitational time dilation which like I said is a concept that we explained in our interstellar episode in season 3 But a good way to think about the speed part is with movement So imagine you are walking inside a train that's moving at 60 mph If you walk forward or you're walking through the train at 3 miles hour someone watching you from inside the train is going to see you as moving at 3 miles hour right but someone outside of the train watching the train go by sees you moving at 63 mph So your speed is added to the trains And time works the same way So if you're moving really fast time will literally slow down for you compared to someone standing still And scientists proved this in 1971 with something called the Hili Keiting experiment So they took two identical atomic clocks which are basically super precise clocks like literally down to billionth of a second So one of the clocks stayed on the ground and the other was flown around the world on a plane But when the plane landed the airborne clock was actually slightly behind the one on the ground I actually always think this because obviously living in Australia and you like you go over obviously it's not the same thing really but you go over different time zones and when I always go back to the UK I would have left Australia like I don't know 7:00 p.m and I go go to the UK and I land in the same day and I'm like this is madness but obviously it's not it's not the same concept but I do just kind of relate it to like time travel in a way but anyway so time actually slowed down for the clock on the plane that's what you're saying yes and this isn't just theory it's actually something that we have to account for every single day so astronauts on the international space station which is moving at around 20,000 km hour actually experience time slightly slower than we do here on Earth So if you spent 6 months up there on the International Space Station you would actually return about 0.02 seconds younger than if you had stayed here on Earth So obviously it's barely noticeable but what if you wanted to go further so we have already established the faster you move the slower time runs for you Now if you traveled at 99% the speed of light time would stretch to the extreme while you would experience just one year entire centuries could pass for the rest of the world here back on Earth So the idea is that you could step onto a spaceship accelerate close to light speed and leap thousands maybe even millions of years into the future But there's a catch You could go forward but the universe is designed so you could literally never come back And Professor Brian Cox has spoken about this Taz we know you love Brian Cox I'm so glad you said that cuz I was about to say "Love him." You got there before me I literally love him And actually I saw him do a little clip of him talking about this and it's what motivated me to do like want to do this episode cuz I was like "Oh my god it sounds so interesting." So yeah he's spoken about this So traveling forward in time is scientifically possible proven by Einstein's special relativity as we've just spoke about But the universe is designed so that time is literally a one-way road So if you leave the world you knew will vanish behind you It will age faster and faster until it's literally unrecognizable You could step into the distant future but there's no physics no equation no loophole that actually lets you return and tell anyone what you saw because they would literally all be dead by the time that you came back which I just think is a really simple but cool concept is you could time travel thousands of years into the future but by the time you got back everyone would be dead And I just thought that was a really cool and interesting concept that essentially the universe is designed in a way that like you could never you can go into the future but you can never tell anyone what you found Yeah that is crazy But speed isn't the only thing that affects time Obviously we spoke about this before but gravity does too And this is called gravitational time dilation And black holes are the best example So think of spacetime like a stretchy fabric When you put something massive on it like a planet it will create a dip in the fabric of spaceime The bigger the object the deeper the dip And black holes are obviously like massive bowling balls slamming into a trampoline So they literally make space time sink Now as we said the stronger the gravitational pull the deeper that dip and the slower time moves for anything inside it Essentially if you spent just a few days near a super massive black hole you would return to Earth millions of years later So we've covered how time travel into the future is scientifically possible even proven Like it's literally been proven Okay so talking about the conspiracy theory of time travel scientifically absolutely you can go into the future We know this But going backward in time that is where things get messy Not just technologically but also logically So it's not just that we don't have the right kind of machine or the tech to do this but there are actual fundamental problems with how cause and effect works So if traveling backward in time were possible it would actually lead to paradoxes which are basically situations where logic and reality break down And one of the most famous examples which everyone's probably heard of before is the grandfather paradox So imagine you travel back in time and accidentally prevent your grandfather from meeting your grandmother Now if that happens obviously your parents wouldn't have been born which means you wouldn't have been born But if you were never born then how did you time travel in the first place so that's the paradox right it creates a loop that contradicts itself So time travel especially going backwards actually kind of breaks reality So if time travel to the past creates these contradictions does that mean that it's completely impossible not necessarily So some physicists argue that paradoxes don't actually happen at all because time in a way protects itself And one of the most well-known solutions is the Novikov self-consistency principle proposed by physicist Igore Novikov So this principle suggests that time travel is possible but only in ways that don't create contradictions So in other words if you were to travel back in time you could never change history in a way that prevents you from actually making the trip in the first place So the timeline is self-consistent Causality is preserved no matter what And this idea is actually rooted in Einstein's general theory of relativity specifically in something called closed timelike curves or otherwise known as CTC's And these are solutions to Einstein's field equations that theoretically allow for loops in spaceime Now if such loops exist then time travel into the past isn't just possible but it's actually mathematically allowed But Novikov argued that even if these loops exist physics would enforce consistency Meaning that everything that happens inside the loop must have already been accounted for in history and therefore no paradoxes are allowed So to break that down a little bit further let's say that you decide to go back in time and stop your grandfather from meeting your grandmother According to Novikov's principle something will always prevent you from changing history in a way that creates a paradox So for example like maybe you would get delayed maybe your time machine quote unquote would malfunction or maybe without realizing it you're actually the reason that they met in the first place So no matter what you do history remains self-consistent and you can interact with the past but you cannot rewrite it And so any action you take was actually always part of history which led to the very events that you set out to change And again this is not just a theoretical idea It has actually been tested in force experiments like the time traveling message paradox So imagine that you are sat at your desk when out of nowhere this random note appears in front of you and it reads "Don't forget to email your professor at 3 p.m So you check the time It's 2:55 p.m and you're confused but you're curious So you decide to follow the notes instructions and you send the email at exactly 3 p.m Now later as an experiment you write the exact same note and send it back in time to 2:50 p.m So you're looking at me so blankly So think about what just happened right the note exists because you found it and you decided to send it back in time but you only need to send it back because you had already received it So there was actually never a point when someone originally wrote it It simply exists as part of a closed time loop Does that make sense right Yeah Like it's just it's forever looping in time because yeah wrote it originally Yeah Well there's no original It's just forever looping So this is how Noikov's principle works So events inside a time loop do not create contradictions Instead they are self-consistent So no matter what the timeline will arrange itself so that everything will line up logically And if you try to prevent something from happening and if you try to change history somehow the universe will ensure that you still end up playing your role in the event exactly as it was always meant to happen And so this is the idea that the past is not rewritten It's just reinforced Can I just say can I just like jump in here that like I find with physics is that it's so theoryheavy like this principle it could be a reality but like surely there's absolutely no way of proving that yeah um okay so I'll tell you about something related to that because this was my question I was like okay well we can't just come up with a theory and be like okay here's a theory and like this is it and I'm just going to explain away I'm just going to explain time travel now just with this random idea that I come up with So I also thought the same thing So in 2019 researchers at IBM conducted a quantum time travel simulation using a quantum computer Now they introduced paradoxical conditions which is like sending information backwards in time in a way that would erase its own existence But every time they did this the system naturally adjusted itself to avoid contradiction And the quantum states always corrected in a way that maintained self-consistency as if reality has built-in error correction to prevent paradoxes which is interesting if you listen to the simulation episode But essentially what I find this demonstrated is that it does happen but I don't necessarily know if they understand like how and why it happens I mean this is kind of where I drew simulation theory isn't it it's giving simulation theory 100% But this is kind of where I drew my line of like this is how much I'm going to understand Do you know what I mean i was like okay I understand this much and I'm drawing the line there So if any of the listeners are interested in reading more about this like please feel free because I'm sure there probably is some people working on like the underlying maths and physics of this Now on that note before we get deeper into how this connects to time travel I have to be honest As I said I really struggled with researching this episode I'm not going to lie Like I obviously love science but physics is really not my strong suit And trying to wrap my head around relativity closed time like curves and quantum mechanics let me tell you my brain felt like it was overheating And that is where Odeik today's episode sponsor actually saved me So instead of trying to read through pages and pages of dense physics papers I used to listen to them instead It takes complex academic research and turns it into structured audio so you can actually understand highle concepts without spending hours decoding technical jargon and reading over the same sentence a million times Because that's my issue is like when I'm reading something that's complicated I will read this same sentence over and over again and it's like my eyes are reading it but my brain is not reading it But if I'm listening to it it just goes into my brain Like it's just straight in there Yeah I'm 100% like that Like I will listen to an audio book and read the book at the same time because you it's like fully immersive experience And you could obviously do that with Demic as well So if you're a PhD student a researcher or someone who just loves science but really struggles with the dense academic writing which I 100% do or demic is actually a gamecher cuz you can listen to the papers whilst commuting walking or in Liv's case while pacing around her kitchen trying to understand these time paradoxes They also have dyslexia friendly fonts and note-taking features as well making it one of the best tools out there for staying on top of research And Odmic offers a 7-day free trial So if you want to save time and actually absorb the research you need we will add the link to Odmic in today's video or episode description So make sure you head there to try it out And we also have a discount code for you guys that will pop on screen now But for now let's get back to time travel Now we've spoken about Novikov's theory but not all physicists agree with this approach Some argue that self-consistency is just way too restrictive and that time travel if possible would not be limited by an unchangeable timeline So instead they propose an alternative one that allows for changes to the past without violating causality And this brings us to the many worlds interpretation of quantum mechanics Unlike Novikov's principle which assumes a single self-consistent timeline the many worlds interpretation suggests that every possible outcome of an event actually happens but in separate parallel universes You knew we were going to talk about parallel universes on this episode cuz how could we not now this idea stems from one of the most famous experiments in quantum mechanics I'm so sorry but we're back with the double slit experiment If you listen to the simulation episode you heard about the double slit experiment I gave a very detailed explanation of that experiment in that episode So if you want a detailed explanation then make sure you listen to the simulation episode And you should just listen to it anyway because I'm biased but I think it was the best episode on this series because well I'm not saying that oh my episode was better than yours I just offended it was really good I just meant that like I enjoyed the science of that episode so much So the idea of the experiment is that you have a barrier in between essentially like you and a wall and you're firing electrons or photons at this barrier Now there are two holes in the barrier and basically scientists were measuring how the electrons or the photons pass through these two barriers and what kind of pattern they produced on the wall behind Now the double slit experiment revealed that particles like electrons or photons do not behave like balls with fixed paths Instead they acted like waves existing in multiple states once So when an electron was sent through two slits it didn't just go through one or the other It actually went through both of them simultaneously creating what's known as an interference pattern But the moment we measure or observe the electron it chooses a single path as if reality is only decided when we look at it Now some physicists take this a step further and suggest that reality isn't fixed until it's observed meaning every possible path still exists somewhere in another universe Applying this to time travel the many worlds interpretation suggests that if someone were to travel back in time and alter the past they wouldn't change their own timeline but instead they would create an entirely new branch a separate universe where their changes took effect The original timeline remains unchanged while the traveler finds themselves in a parallel reality This would mean that time travel doesn't break causality because rather than altering an existing history it simply shifts the traveler into a different version of events And this raises an unsettling question If time travel has ever happened we would never know because our timeline would remain untouched And if that's the case is it really time travel or just an extremely complex way of moving between parallel worlds i actually feel like I want to align myself with the parallel universe theory because I feel like you know we touched on this on simulation theory about um Mandela effects and loads of people say that we entered a different like a parallel universe when as a result of these like Mandela effects So like there's no evidence of it in our history but people still remember it because like they've shifted into a parallel universe That's like my conspiracy theorist's hat on but and obviously going back to Brian Cox I've seen him do talks before and he talks about parallel universes So he I feel like he backs this theory as well So if he backs it I back it If Brian Cox backs it we back it So culture backs it literally So okay just to kind of sum up time travel into the future absolutely possible in terms of like what is kind of allowed by physics and gravity and speed and all that sort of stuff Absolutely possible But time travel into the past seems kind of like hard to say Yeah that's what it looks like And that's before we even talk about the biggest problem right which is like even if time travel to the past is possible like how would you even do it oh my god is this the part where we talk about wormholes yes we love a wormhole on this podcast So the idea of wormholes comes straight from Einstein's equations So in 1935 Einstein and physicist Nathan Rosen discovered that mathematically spacetime could in theory fold over itself and create a tunnel between two distant points And these actually became known as Einstein Rosen bridges or what we now call wormholes So we've said this analogy before but you can imagine spacetime as a two-dimensional sheet of paper Now if you want to travel from one side to the other you'd normally have to cross the entire sheet But if you fold the paper and punch a hole through it you could jump instantly from one point to another And that is the basic idea behind a wormhole It's essentially a cosmic shortcut through spaceime Now if wormholes exist and let's just say that like there is actually no evidence for wormholes So let's just put that out there right now Again we spoke about that on the Interstellar episode But if wormholes do exist and if one mouth of the wormhole is moving at relativistic speeds or placed in a strong gravitational field time dilation would mean that the two ends of the wormhole experience time at different rates right this means that a traveler stepping into one end could theoretically exit at a different point in time So like in other words a wormhole might not just be a portal through space but it is actually a time machine But and this is a big butt there is a huge problem because we have zero evidence that stable traversible wormholes actually exist And even if they did keeping them open long enough to travel through would require something that we don't actually know how to produce yet Negative energy What is that so negative energy is a bizarre concept that comes from quantum mechanics Just like every everything that comes from quantum mechanics is bizarre I feel But under certain conditions quantum fluctuations can create regions of space with less than zero energy Essentially it's a vacuum that exerts repulsive gravity And this kind of energy could in theory prevent a wormhole from collapsing which would keep it stable for long enough to actually pass through And some physicists suggest that the Casemir effect which involves tiny quantum fluctuations between two closely spaced plates might be evidence that negative energy is actually real So without negative energy any natural wormhole that formed would actually just collapse instantly So even if one did exist the gravitational forces inside would likely actually just rip apart anything trying to actually pass through it So while they remain a fascinating theoretical possibility there's actually no real path to making them work as time machines at least not yet But I feel like we kind of have something similar to that in Black Holes right because going back to our good friend Brian Cox he definitely mentioned um like warped time If you were to like approach a black hole what's is that is that related to that in any way mhm Yeah And again I think we did speak about this a little bit on the Interstellar episode but there is the idea of using rotating black holes And some physicists speculate that if a black hole is spinning fast enough it might actually create a stable possible wormhole inside Meaning that yes you could enter one side and emerge somewhere else But again this is purely theoretical And even if this did exist like a wormhole inside a spinning black hole like even if it existed we would literally have no clue how to navigate it without being crushed So the short answer is no We can't use wormholes or black holes for time travels At least not yet But the long answer is maybe we could if we ever figure out how to generate and control negative energy or if new physics reveals stable traversible wormholes I mean the idea isn't totally off the table but for now unless you're willing to take a one-way trip into the distant future by hovering near a black hole time travel remains stuck in theory not reality Oh I'm kind of sad about that I mean same because I'd love to go back in time and change a few things you know i always feel like No regrets No regrets I wouldn't want to No regrets No regrets Yeah So we've talked about time travel but let's zoom out like way out So the universe itself has a clock and that clock started ticking 13.8 billion years ago with the Big Bang Before that as far as we can tell time literally didn't exist But if time had a beginning does that mean it could also have an end well right now physicists think there are three main ways the universe could end and each one has massive implications for time itself So first up we have the big crunch theory And this is the idea that the universe will eventually collapse back in on itself essentially reversing the big bang And if this happens time itself would literally end as the universe reaches a singularity just like the one that birthed it And some theories even suggest that if the universe collapses in a big crunch another big bang might actually follow essentially restarting time in an endless cycle And if that's true then maybe time is just an infinite loop playing over and over So like is time itself a closed loop i don't know I just thought that was an interesting concept But having said that right now that isn't the leading theory And that brings us on to the big freeze because right now the universe is expanding and galaxies are moving far away from each other Space itself is also stretching But what's weird is that this expansion is also accelerating So instead of slowing down due to gravity something is actually pushing the universe outward like faster and faster And that something is dark energy And if this keeps going we'll get what's called the big freeze So here is what happens Essentially as galaxies spread apart stars will run out of fuel and burn out Black holes will slowly evaporate through Hawin radiation and eventually all that's left will be a cold dark lifeless universe Well that's depressing And at this point time wouldn't stop exactly but it would lose all meaning And again we're here back with the philosophical questions But if time is defined by change by events happening if nothing is happening there's no movement no energy and no interactions then is time even moving is time even a thing anymore and then this is our last idea What if dark energy energy doesn't just keep the universe expanding but it actually grows stronger over time now this is the idea behind the big rip and it is terrifying So right now dark energy is pushing galaxies apart at an accelerating rate but in a big rip scenario it wouldn't stop there Instead it would continue to strengthen it until it's not just expanding space but it's literally tearing apart everything inside it Eventually it would go even deeper ripping apart molecules atoms and then even the fundamental particles that make up reality And finally dark energy would unravel the very fabric of spaceime itself And if this happens time wouldn't just stop but it would cease to exist altogether So if time has a beginning and an end can we ever truly time travel or are we just passengers on like a one-way journey through time with literally no control in a big crunch scenario maybe time like I said loops back on itself meaning past and future could just be different cycles of the same repeating universe which is scary And if that's true perhaps time travel isn't about jumping to another moment but instead it's waiting for the cycle to restart And in a big freeze time might just stretch out forever but eventually it just literally wouldn't matter anymore because there's nothing left to experience it And in a big rip time wouldn't just stop It would literally be ripped out of existence And there would be nothing left to even travel through So right now we do not know which of these futures will happen But one thing is clear Time is not something we just move through It's something that could one day end And that might just be the biggest time travel paradox of all Mic drop Oh my god I've come away thinking like time travel is going forward in time absolutely possible backwards in time there's no real evidence necessarily that it would be possible that's how I feel anyway I don't know how you feel live I feel the same but I'm also a fan of the parallel words the many worlds interpretation I'm a fan of that and I think I'd love to dive a little bit more into the parallel universes So we'll definitely have to cover that in like a future episode probably in a different series But yeah for the listeners of course as we do every single week we will pop a poll on our Instagram So you'll have to come over and let us know what you think of the conspiracy theory around time travel I mean your answers will probably be a little bit more nuanced than just like a yes or no but come over and get involved anyway Um so with that that rounds off the science for today's episode And I think we have a listener story that we really need to get into So let's get into the laboratory section of today's episode [Music] Okay we've had a listener write in and the subject line is betrayed by my lab bestie So let's get into the email In 2023 I began my masters in another university across the country I ended up joining a lab who took three master students in one go And it was exciting because we were all girls in STEM and all the same age And one would have assumed that we would have been so close given the proximity and common interests However that is not what happened One of the girls who was at this uni since undergrad was extremely insecure in herself and her abilities and kind of felt threatened by me since I wasn't like stupid I guess However it wasn't just a little jealousy She [ __ ] talked me to the entire department before anyone even got to know me And it was actually so bad And I felt so lonely It was such a horrible experience And I felt anything I did was just not good enough Even after speaking to her numerous times it never got better And the only thing that made it better was honestly completely removing myself and finishing my lab work earlier and just working from home And even though I love my project and supervisor I never considered staying for my PhD since she's also staying and I cannot go through that for my mental health Toxic lab culture is honestly so unhealthy and I honestly hate it Oh that is a lot That is a lot I feel like we've done so many stories recently about Sorry my cat's just coming to join us We've done so many stories recently about toxic labs toxic academic culture and I honestly feel like this is just going to be a running theme on the podcast for as long as we're doing these liberties like it is going to be a running theme because it's just so so common for me Honestly I can't lie The most disappointing thing about this story is the fact that there was like three of you girls You all started out together and you didn't become besties I don't know why I feel like that is the most painful part of this story because you know women in STEM we should be supporting each other and like uplifting each other M yeah I do definitely think like being in science is like weirdly competitive Like some other people are just so competitive about what they want to achieve and it's like oh my god because do you remember the my friend stole my research idea laboratory from last season where like her friend literally stole her whole idea Not only are we not like supporting and uplifting each other but we're actually backstabbing each other because this this girl even said that the other girl was like [ __ ] talking her to the whole department Yeah Literally I'm like it's hard enough being women in STEM Like we don't need to pitch against each other Do you know what I mean like doesn't make literally any sense I feel like if people worked together more in the labs you'd actually get so much more done like I went from a very non collaborative lab and it was literally just me doing stuff and then I I've since moved to a lab that is quite collaborative and everybody's kind of willing to help out and you obviously are then part of so many more projects because you help other people they help you and it's like you kind of expand your own experience and also if you help enough then you get your names on more So it's just like come on like let's just all work together and then it builds up like your experience and your academic CV because you got more papers published and stuff Also the science science world is like so heavy on networking and collaborations Like in academia it's really good to have these like networking opportunities because if you meet people that that's how you create new projects and apply for new grants like if you're just stuck within your own sort of institute then those opportunities never come about So if you're this person who's like shit-talking someone else in the lab then no one's gonna want to collaborate with you Just saying 100% 100% And like what are you even what is she even saying about you because what what have you even got to say about cuz she said she works from home So I'm assuming they're like not even really in the lab I'm assuming they're by informatics But everything you said still stands cuz obviously I was fully computational and like my supervisor was very good at encouraging collaborations Did she would go in early to finish lab work or she finished lab work true but still I just don't what is she even possibly saying about you that to the point where she has to go and talk to other people in the department do you know what I mean I get maybe talking to people in your office and having a little gossip I mean personally me I wouldn't do it like I definitely don't gossip about like other students and people on my level yeah maybe in my office we have a little gossip about the PIs can't I yeah exactly I mean it's got to be done but like we're definitely not like gossiping about like other people on our level or like below us That's weird No talking either Like Yeah But one thing I will say is like I'm so glad that she decided not to stay in this lab cuz I think so many people just think okay it's so easy if I just stay in this lab I've got an easy PhD position like lined up for me but I'm so glad that you didn't commit to like another three to seven years depending on like where you're from Cuz like if you're in the US that's like 7 years right to do a PhD But if you're in the UK 3 years But either way I'm still so happy that you decided to just get out of there and not commit to like another 3 years Yeah But she didn't say that she was going to do a PhD somewhere else So I hope it hasn't tainted your entire view of it Like fair enough don't do your PhD there but don't let it put you off doing a PhD Like don't let this girl get one up with you girl kick you out of academia because she's not nice Like don't let her win babes No I fully agree Like you can leave academia after you've done the PhD because I'm fully here for that But I say that I literally work in academia But um yeah No I agree I do want to know Yeah I wonder what is what is she doing now m I'd love to hear from some people in industry as well cuz I reckon some rounchy gossip goes down in industry Yeah 100% Do you know what I mean cuz I don't think we've ever had any like industry listeners right in like it's always academia and like we always get the topic I think that says a lot more about academia Yeah this is true But I feel like No I'm I'm I think there's some good gossip that goes on in industry So like yeah if you're listening and you're someone who parties as well No we've spoke about this before The work Christmas parties are crazy Some random stuff goes down at work Christmas parties So if you are someone who works in industry and you have any of that gossip to share with us maybe it is one of your crazy Christmas work party stories or maybe I don't know just like some random office gossip let us know because we need to we need to start figuring out and understanding what gossip goes on in industry compared to academia You can find the anonymous link in today's episode description or video description if you're watching on YouTube or you can just email us at socultureodcast@gmail.com whatever you prefer But with that that rounds off episode 5 of Debunked So we will see you guys in next week's episode where Taz what are we going to be covering yeah we're gonna go back to the virus and COVID theme and we're going to be talking all about microchips and vaccines But for now that is the end of episode 5 And we will see you guys in next week's episode Wendy say goodbye Hey

Transcript for:Exploring Time Travel and Its Theories

Transcript for:
Exploring Time Travel and Its Theories