The guy rocking up to the nobel prize ceremony after violating CPT symmetry: Announcer: Congratulations. You've destroyed half of physics. Here's your prize.

"but inverted. You owe us a million dollars"

The other half is still fine... Because you destroyed half of physics.

I would prefer someone broke CPT symmetry instead of not, or leaving it uncertain. If we break it, it means our current theories will need to be changed, and as such we get a more accurate perception of the universe.

@Zacyquack Of course, breaking the symmetry isnt a choice. If it is possible to break, we can't just ignore it to preserve our current theories. We MUST understand the universe.

Well... 'you showed us, that a lot of assumptions about reality might be wrong and needs to get re-examined. Thanks a lot mate. Her's a medal and a coffer of money.' As it should be.

Known ways to break a CP law: - super freeze a particle and add magnetic spin - refuse to "pick up that can, citizen"

Now, put it in the trashcan.

Gear multipliers and magnetically charging mercury

Maybe Black Mesa, That was a joke, Fat-chance, haha.

@Rohith Balaji *that was a joke, haha, fat chance

*THROWS CANA ND RUNS*

I think Nolan liked this video so much, he made a movie about it.

Nah bro veritasium got the idea for this video from tenet. You just see it inverted

he even mentioned another Nolan movie, inception

No he didn't, but should make a movie about the mirror world!

@Somenath Garai yes he mentioned inception

"she and a team of low temperature scientists" is that a nerdy way to call them cool?

ohhhhh yes!!

Well, yes, and no.

That they are dead?

The Monster Under Your Bed if Marie Curie was a renowned scientist before then, it makes sense that women were in physics

No, they should be very cool

How does this man manages to make every single topic so interesting and enjoyable in each video?

me to brain stretched

Also I wanted to say thank you for making these videos I really do enjoy them. You are awesome! I am blind so I can't see the graphics unfortunately but your explanations are very nice and I love doing math in my head so it's enjoyable to see you theorize in my head about all the things that you explain

Interesting, how did you manage to type the comment then cuz you need a cursor for that. How do you see what you type?

@Yashaswi Kulshreshtha I use dictation and I just talk back or voiceover based on the device it reads me things on the screen.

it must be soo interesting being blind i often fantasise about it! visible light is only one part of the energy spectrum anyway and can limit a person's perception of reality so i imagine eye blindness removes reality blindness lol. like when you think about it youre conscious of two dimensions at once because you interact with this physical dimension while perceiving it in a 4th dimension (imagination) at the same time. people without eye blindness only do this on occasion while you use it pretty much constantly so i'd assume are a master of it by this point!

@𝚝𝚑𝚎𝙴𝚗𝚍𝙸𝚜𝗡𝗮𝗶 I don't recommend it lol. However I've learned to deal with it and there are some things that are better like understanding a person in the characteristic just by hearing them so you can look past there facade. Unfortunately I get discriminated quite a bit. I wasn't even allowed to finish my PhD because I lost my eyesight The school denied me even though I only had a year left.

Low temperature scientists? Those guys sound pretty cool.

Get out

Ouch!...that was so bad it hurts! :-D

noooooooooooo!!!!!!!!!!!

whiz 85 im crying 😂

Yeah, they chill out often ;)

I love how, after getting a bit started on subnuclear physics with my first nuclear and subnuclear physics course, i can now see this and not only properly understand what he's talking about but also seeing where some things are slightly simplified to make it easier to understand It's really nice learning and finding evidence that you've learnt

Imagine two people playing chess and the one observer who is observing that doesn't knows the rules of chess before hand As the game proceeds the observer keeps learning and Now when he sees a pawn walking single step straight way he writes down that pawn walks forward and now when pawn goes diagonaly to attack some other opponent piece. The observer is in surprise thinking that it broke the laws of chess Same applies here Nature is chess player and scientists are observer in this never ending chess game Always discovering new moves - Feynman

Ah feynman

Not bad except that nature is SO much more complicated than a chess player learning new moves. The way chess pieces move and the rules of chess are exponentially (and "exponentially" the biggest understatement of all time) easier to discover than nature.

​@Blade Runner6997 You could also make the same argument with glitches in video games. When Pokemon Red/Blue came out, I don't think anyone had any idea that you could just, somehow manage to scroll down past your inventory to find some strange item that executes your Pokemon data as code. But technically, it's still within the rules of the game's programming. Thus, I wonder if there are "glitches" in the very universe we live in.

@Benedani A glitch is when a program doesn't behave in the intended way. If the universe has glitches, it would mean it doesn't behave in the intended way. What is the intended way?

I am the 70th like

I have that audiobook, We Have No Idea. It’s really entertaining, groaningly funny, and deeply fascinating. It really does explain clever, complex ideas in a manner that anyone can understand.

These just keep getting better made and easier to understand. Veritasium rocks more than ever.

This really makes me want to find an example that breaks CPT symmetry to see the entire science world implode. That would be funny *laughs in super villian*

i mean every single scientist will be thankfull to you to have shown a path to a truther truth

@captaine flow chapka reminds me of the faster-than-light neutrinos "discovery" few years ago ... there were lots of interesting debates until they found it was just the systematic error it looks like all the low hanging fruit were already taken in physics

@Libor Tinka It’s probably better that we keep picking the lowest fruit, rather than pick the higher fruit and have no idea where the others are.

A truther truth 😂👍🏻

It won't really break any laws it would just mean that the same laws would have to be written again with considering the fact that cpt symmetry is not a thing which a lot of physist assumed back in the day while making these laws like Einstein. The symmetry only makes physics easier that's why it will be a hell a lot of work to complete all the theories of the past for unsymmetrical systems.

"The parity's over, guys." That nerdy dad joke made me laugh way harder than it should have.

I tried to not laught at that, but then I saw your comment and burst into laugther lmfao

I don't get it.

@The Random commentor it's similar to the phrase "the party's over"

​@Hayls if you actually pronounce that, then it becomes funny lol :D

It sounds like Doofenshmirtz talking

Though I don't know much about them compared to what there is to know, I love quantum field theory as well as special relativity. This means that the possibility that both of them are wrog because CPT "breaks" (if you can put it that way) has become one of my greatest fears.

Hey @Veritasium! love your videos, I just wanted to ask, which software do you use for these amazing animations?

It would be very interesting to have CPT broken require a lot of rethinking a fundamental laws of physics. I think it would be fun a whole world of discovery and begin again

Excellent video. The way you explain such difficult things in such a cool way is really commendable. 👍👍👍

Thank you for all of this. You are inspiring me, and I'm sure millions of other. For that I truly thank you.

- Honey, are you ready for a vacation? -Sorry, dear, I have some fundamental physics principles to topple!

Women can never be ready on time!

Again? Remember the last time you tried doing that? I think the cat still has nightmares from being stuck in that box.

@Manjoume Thunder What cat?

@Ajax He's referencing Schrodinger's Cat Experiment

If anyone could explain the correlation between disproving CPT and how it would affect our beliefs on special relativity, that would be well apriciated.

All fundamental physics have conditions that time , charge is symmetric throughout universe

All conservation laws depend on symmetries. For example in special relativity, the reason why an object with no resultant force acting on it has a constant velocity, is because the universe shouldn't care about where we set the origin of the 4D coordinate grid (metric) we use to map the objects motion (Lorentz invariance), and as such nothing should change - the conservation of (four) momentum depends on this being true. Since the frame of reference we choose to define as absolute rest (for say an experiment) is arbitrary, the laws of physics (the equations we use) must be invariant under changes in the velocity of our reference frame. Thus your 4D velocity is constant (c). So special relativity depends on CPT symmetry for its axioms to be valid (so that there is a way to reverse time and the laws of physics upholding). It also turns out that quantum mechanics depends on this being true for bosons and fermions to be distinguished, but at a fundamental level CPT violation would destroy basic assumptions like that the universe doesn't care about which charges are positive and negative - which if true means that charge is not fundamental, or even that the assumption that forces are definable by symmetries is not valid (which basically all physical theories assume).

@V1ND1E Would violation of CPT violate the equivalence principle too?

CPT just means I have a good excuse for being late to any event. [that was a joke!] Good video! Hey, if I understand it this well, then you did an awesome job explaining it. Thank you!

Exquisite summary, as always.

This is one of my favourite videos ever. I first saw it a few years ago and it still baffles me.

We did CPT-Symmetry in theoretical electrodynamics just a week ago, very interesting to have it put into a larger context.

I like the title of Jorge's book. I wonder if he realized while writing it that one of the many things we have no idea about is that there is no conceivable way that we can know for certain that time actually flows in only one direction. We can only perceive it that way, of course, but if it ever did reverse, or speed up, or slow down? The processes in our brains that lead to consciousness would do exactly the same, they would reverse, speed up, or slow down, as they are embedded in time. Think about a starship, traveling at or near the speed of light. Einstein taught us that time would actually slow down for the crew on board (though everything would seem normal to them), as well as for their clocks and other instruments. If it can slow down, time can also speed up. If it can do both of those things, who's to say that it can't reverse its flow completely in certain situations? And we would have no way to detect it.

You should do a video on what is in between particles. Air particles are spread apart and bouncing off of each other, so what’s in between those particles

Sir you are very brilliant! I am extremely motivated by you and I want to become like you 👍🏾🙏

I must say Derek that, I'm really inspired by all of your research and, as a true fan of physics since the age of 15, I would say, what if you and me together break the last remaining symmetry?😅 Anyways, another brilliant video.

Salute to those people who don't understand a single thing here but still come back for every veritasium video

Some of his videos, like this one, I feel like he doesn't even understand what he's saying. Felt like he was just reading wiki definitions and giving their examples

@Gage McMahon Just type latest standard model of particle physics. You'll understand this video with ease 💯

Yay! Here we are!

😂😂😂😂😂😂😂

@Gage McMahon well he has a phd in physics so he definitely knows more stuff than some people

All the videos Veritasium made never failed to, overall, satisfy our thoughts on understanding the conundrums of science, if one is yet to be proved then they always backed it up by recalling another temporary consideration for what's going on with it. It was nicely done as always!

There's some videos you can rewind and the backwards playing may not be obvious, like if to was a pendulum swinging. In that case, the pendulum looks the same forward and backwards. Entropy prevents such temporal symmetry for certain things. For example, if you reverse a video of an egg breaking, it's obvious that it is backwards.

Lightning must be really scary in reverse. Like, imagine a bunch of charge inside the earth just _r i s e_ to one particular place before *ascending*

It is a very interesting phenomenon... I like to think it's just a normal part of the way things balance out.

Somehow this video gave me a better understanding of spins in a shorter time than some other videos that are entirely about spins.

I had a doubt in the experiment the observer was beyond the object (like -> observer-atom-mirror) in this case, the spin direction changes from clockwise to anti-clockwise, but if the observer is in between mirror and atom then in his perspective the spin will be in the same direction(clockwise or anti-clockwise in both mirror and real-world). I am not sure but I feel that for parity symmetry we should keep the observer in the middle of the object and the mirror. @Veritasium

"Hey, so, ready for that vacation?" "I can't, the weak force may violate p-symmetry." "Then there's only one thing we can do!" "Stare at cold metal atoms!" -A physic(s)al relationship.

Gareth Dean ahahah gareth that's been a lot of time without seeing you around

+

Hey dude. It's been a while. :)

The PBS Spacetime comment squad

+Vampyricon Lmao I guess

I could totally see the person discovering CPT symmetry breaking keeping it a secret as to not just destroy physics

I‘m just happy that you mentioned Prof. Chien-Shiung Wu, one of the physicists I truly admire

Amazing video ,it was so different for everything I've seen before

I think a better way to combat the counterintuitive nature of this concept is to introduce multiple “light bulbs” in the circuit, some of which are “before” the light bulb in question (henceforth known as Light Zero or L0), and some of which are “after” that same light bulb, but all of which are in the same in-series circuit. In that case, given ideal conditions, the light from the bulb closest to the switch-flicker would reach that person first, in 1/c seconds as per this solution. Light from bulbs both “backward” and “forward” of this L0 bulb within the context of the (albeit impossibly perfect) series circuit would all appear to become lit LATER than bulb L0. This would better demonstrate that the location in the circuit is less a determining factor in the solution of this problem than the physical limit of C, resulting in bulbs “further away” than L0, though intuitively lit “earlier”, appear to brighten later than L0. It’s the proximity to the switch-flicker that defines the delay for any given Light Bulb in the circuit… thus a general answer for the time taken for a light bulb visibly brightening would be time in seconds = d/c, where d is the distance of the bulb from the operator of the switch. This is more general than 1/c, which is only correct in the original problem because d=1. The video isn’t incorrect, it just could have made this distinction more clear… 1/c is a specific solution. d/c is the general solution.

What technology would they have had to measure for this parity experiment back in the '50s?

I always thought that the "right hand rule" of magnetism demonstrated that the forces of our universe are not symmetric, but I suppose in the mirror it would just be the left hand rule.

Everything's relative after all, lol...

The 'right hand rule' you learned is actually a handy way to explain _pseudovectors_ to people: see, the 'spin' in the vid has basically the same behavior of a vector *L* = *r* x m *v* , with *r* the position (say of a point particle, for simplicity) and *v* just the velocity d/dt ( *r* ); as you put *L* in front of a 'mirror' (i.e., change _vectors_ *V* by - *V* ), both *r* _and_ *v* swap sign, so *L* - or spin - doesn't change sign at all!

As +thstroyur pointed out, the right hand rule is always related to pseudovectors. A good way to think about this is that pseudovectors require a sign convention. They're like vectors in the sense that the have both a magnitude and a directional axis; but, they're unlike vectors in that there's nothing intrinsic that picks an orientation along that axis. However, the _relative_ orientation of pseudovectors is meaningful; so, it's useful to create a convention by which we can just assign orientations in a self-consistent way. And, that's what the right hand rule does. Everything would work just as well if we chose the left hand rule convention and applied it universally; but, we didn't.

Ah! So it's sort of like how we arbitrarily assign "i" and "-i" (the positive/negative direction along the imaginary axis), in that if we replaced every instance of one with the other (conjugating everything) nothing would break. Or how we always draw circles determined by (cos(theta), sin(theta)) in the counterclockwise direction simply because of how we orient the axes on our paper.

Not too related to your comment but it reminded me of a funny moment in hs. We were learning about the right hand rule in class and one of my friend raised his hand and asked the teacher "what if you are left handed?" Man... the amount of face palms that day xD Can never forget that moment LMAO

Increasing entropy and arrow of time, both look to be a result of consistent (in scale) and continuous breaking of symmetry by subatomic particles.

Yes but the 'Right hand mehtod(RHM)' is something we made so ... if the RHM is the reversed in the mirror to a LHM then it makes perfect sense why it keeps going the same way even though it's the mirror . Because in the mirror it should go that way because your /Mirror right hand rule applies there @Veritasium

I thought the reason we perceived time to only go in One direction was because of the way our brains work.

First, I should thank you for your awesome videos! With all due respect, this time symmetry is related to the evolution of a physical system, which is different from arrow of time dictated by the second law.

Sorry, I think evolution time is the one rising from the second law.

What if time moves back randomly, but we don't know it because every recording, memory or action is reverted?

The cool thing was that they acctually had to travel to the "mirror" world to do this experiment, just like they travled to pandora to shoot avatar! great video and well explained!

XD Not really; they knew where the spin was pointing (say 'up') - then all they had to do was measure if there was an excess of particles coming upwards or backwards, boom! P was broken

Rickard Rocks was w

mirror world makes the better doughnut holes, ironically enough

whats the mirror world? how do you know itll act differently there?

The joke Your head

In order to test CPT for violations, I would first suggest testing CT and PT symmetries.

Then why don’t you test them? (genuinely)

Violating CT (under CPT invariance) is the same as violating P which, as Derek explained, has already been observed. Similarly, violating PT is equivalent to violating C, which happens in the weak nuclear force too

I think this is very clearly explained. I find this idea of symmetries fascinating and, along with QFT, somehow deeply satisfying to think about. Thanks for this.

Also great explanation of what breaking time symetry looks like.

this is why my favorite phrase is "impossible in science is only temporary" because given enough time science will figure out how to do anything, how to do something that is considered impossible, as it's not a matter of being possible and impossible, but just a matter of time before something considered impossible is made possible.

I feel like the part around the time symmetry violation could have been better explained. After watching the video, it seemed as if violating one of the "sub-symmetries" should lead to the collective CPT being violated, but then the video seemed to conclude that it might still hold, but that we should doubt it even though violations have been proven in each "sub-symmetry".

I love watching videos like these and pretending to know exactly what hes saying. "What?! The weak force?! CP? Preposterous!"

You have the entirety of human knowledge at your fingertips. Learn about it Edit: yeah i definitely came off as more arrogant here than intended y'all, sorry for that. I must've been in a mood. To be clear, all i meant is that anyone with internet access has the means to learn just about anything they could think of. Historically, access to knowledge has been a resource of only a few, so we're beyond privileged to have that access now. As for the grammar, i mean, i tend to fat finger everything i type so idk what to tell y'all about that.

@Boog no u

500th like 👍

Omg same!

@Boog Which includes social skills, just saying.

I have been watching your videos for about a year and im 15 years of age at this point. This is probably the video ive had the most easy time to understand! Also very interesting, thanks Veritasium!

If you were to look at where the magnet would be in the mirror world as you align the nuclei then there wouldn't be a confliction, the electrons would move with z in both because you would be holding the magnet in the same place (relative to z) in both.

I love the way your brain works you make it so underable.

Almost 100 years and extreme improvements in technology later, people are still trying to disprove the one theory while Albert keeps laughing in his grave.

I love little more then when scientists say that something is nonsense and then are immediately proven wrong when they try it themselves

Science doesn't mean its right, it just means its the closest thing we know of to being right at any moment.

ya and your god is absolutely right/correct

EXACTLY

A R G O N Λ U T I'm fairly certain Corkas_ was saying that was an advantage.

Careful there Argonaut, you almost dropped your fedora. Science is not the body of knowledge, science is a process for testing ideas. At least when conducted honestly. It is when a hypothesis that is expected to come true (for all the body of knowledge would put forward) but does not, as is presented in this video, that the value of science becomes strongest. Unfortunately, when science is not done honestly, we have experiments repeated until the hypothesis is confirmed, and then that data set alone being published. Regardless of how many times it took.

I don't think that's quite right. The essence of Science is knowledge, in the sense of knowing what is and what isn't, or the difference between fact and fiction. Science is more like a tool. If it produces the "wrong answer" it's human error, like how the scientists in the video keep trying to save their preconceptions instead of genuinely trying to understand. It's why I hate things like theories. They look to me more like people trying to force their ideas onto the universe instead of searching for truth. And that kind of human arrogance is why we have the dogmatic pseudo-religion of "because science," and why education tries to indoctrinate children into believing things that aren't proven instead of focusing solely on what we know. I think it ultimately dilutes science over time. edit: Kind of like what firebornliger said, yea. I was just replying to OP, sorry.

I've been binge-watching Derek's amazing videos... and I gotta say, in this one, he looks realllly baked ...but it's okay, he's Canadian and Californian, so its allowed either way (plus I'm sure it was for science anyway) 😉

I read a segment in an optics book that had some of the work of Feynmann and it showed that if a particle begins to travel backward in time the charge reverses and it becomes an antiparticle. An electron traveling backward in time is a positron. Photons having no charge appear to travel backward in time when they are violating the light-speed limit. These are called tachyon gamma rays.

Here's a question relating to your video on the one-way speed of light: if the one-way speed of light is NOT c in all directions, would that not violate parity symmetry?

With regard to the arrow of time, the dominance of matter over antimatter, and time symmetry, perhaps at the big bang, there was a complimentary reactionary big bang going in the opposite direction in time. This mirror universe would be dominated but antimatter. Perhaps even anti bosons? If anti particles behave like the time reversed version of their counterparts, then as they bang backwards in time, they behave just like regular particles. They would think we are anti particles.

The weak nuclear force seems to misbehave quite often. It's why a friend of mine keeps saying stuff like "The weak nuclear force is a gremlin on the wing of particle physics."

Physicists aren't lawmakers. I would be more inclined to say translators. The laws of physics can't be broken because physics itself writes them, so if we mistranslate something we observe, the translation becomes wrong, however the more we learn the more accurate that translation becomes.

As with many laws, there can be multiple interpretations.

Ryan Vigus i think you missed the point he was making. He wasn't doubting the validity of physicists and the laws they discover. He was just criticising the use of terminology such as "it broke this law of physics", inputting that it's more accurate to say "we misinterpreted this law of physics" because no law of physics can actually be broken

@Dizzy You are mistaken in believing that there are any laws at all

Doesn't it bother you that he talks about that as if a particle had destroyed a laboratory and killed thousands of people. Really, this things happens from time to time, it's no big deal. And he repeats the same thing lots of time in a very fast speed and in the most complicated manner he can to make it sound more complex.

That is GOLDEN speach there

It'd be interesting then to see the rework if cpt symmetry is broken since what we do have matches so closely with what we observe

Really quick question. I'm an undergrad studying chemistry, but would chirality also be used to determine if we're in the mirror world?

Theoretical physics researcher here: there would be virtually no way to determine which universe is the ‘mirror’ universe due more to one’s own concept of a ‘real universe’ than any rules Basically: even if there were experiments one could perform to determine the ‘left hand’ universe from the ‘right hand’ universe (and there sort of are), it would still be your own universe that’s real to you, and mirrorverse you will feel the same about their own reality Because you’re a part of your own very real, very existent universe, left or right handedness means little to what realness means for an observer

@Orion Gurtner true, but Veritasium called the right handedness universe the "real" one because it is the real one for us and so calling them left or right handed would just confuse a lot of people for no real gain. So while your comment is technically correct, I think it is unnecessary and irrelevant for this comment (I don't mean to insult you but I couldn't phrase it differently while keeping the meaning). if you disagree, I would LOVE to talk about this more as I find this concept fascinating.

@Orion Gurtner yes. My point was that it is kinda worthless arguing about what universe is "correct" or if there even is one, because veritasium used those terms for an easier explanation. Let's agree that we are on the same side?

@Minecrafting_il I definitely agree, I just like talking about it, it’s truly fascinating when you get down to how that affects the quantum ‘bits’ of reality, but it is largely a null question Granted, some scientists (I forget The Who and where) might have found that inverted universe, so it might _not_ be that null of a question, who knows? I really hope that we (our universe and the other universe) get to look at each other’s universe, cause that would be wild for both sides of the proverbial coin

If CPT symmetry was found out to be false, I dont think Special Relativity and Quantum Field Theory would not be totally destroyed, but some special conditions might be added to them. That being said I don't really know much about them, this is just my imagination.

I wish we had more people like you i listen more than my ussual teacher cause they only give me 1 explanation 2 sub lessons an assignment and 6 billion papers

I don't know why, but the fact that clockwise spinning objects still spin clockwise in a mirror has broke my mind

Your video covers up the fact that Wu's work did NOT win HER the Nobel Prize, but won it for the two theorists, Lee and Yang.  Her contribution to the discovery was largely overlooked until she was awared the Wolf Prize about 20 years later.

Add Lisa Meitner (nuclear fission) and Rosalind Franklin (DNA) who also made discoveries that their male colleagues were given more credit for AND received Nobel Prizes for

Honestly, and I say this unironically, most noble prize winners are somewhat undeserving of the prize anyway, as science is the sum of all of its parts, discoveries, changes and paradigm shifts. It's like Eurovision song festival winners, it's not a matter of the 'best song' winning. There is way more politics involved with these prizes as one might assume. Keep in mind Henri Poincare , Josiah Willard Gibbs (on par with someone like Lorentz ) , Ludwig Boltzmann , Wilhelm Sommerfield , Lise Meitner , Emmy Noether , Edwin Hubble , George Gamow , Robert Dicke , James E Peebles , Stephen Hawking etc. etc. never ever got a Noble Prize, despite being just as deserving of one, arguably more than any/some of the winners. Long story short, Nobel prizes themselves aren't that great of an indication of someone's true contribution to science. (It reminds me of how a lot of people who actually have a PhD in anything, aren't at all the people with the absolute highest IQs. In my mind this reveals how our scientific communities are broken when it comes to the potential progress, assuming intelligence itself plays a significant role.)

@Vito C _"... Rosalind Franklin (DNA) who also made discoveries that their male colleagues were given more credit for AND received Nobel Prizes for[.]"_ By the time Watson, Crick, and Wilkins got their Nobel, Franklin was dead, and the Nobel rules do not allow posthumous awards.

@Vito C On the bright side, most people agree since the 60s that she should have gotten the Nobel Prize as well, including being invited to a meeting of Nobel laureates and, something which is a much bigger accomplishment, Lise Meitner has an element named after her.

No Wu, Wu pissed on my rug.

I thought entropy was also symmetric in time, i mean, it’s not impossible to have a decrease in entropy but very very very very very unlikely. Hence, if you put a system in a perfect state, theoretically you should be able to watch a spontaneously reduce in entropy

There is a fun thing about symmetry that you can realize with a bit of a thought experiment. Imagine we make contact with an alien race. They aren't on our world and we simply communicate with them through an audio box. When we start off communicating with them we might start off simple, by doing something like sending beeps in a pattern that could be interpreted as intentional and see how they respond. For the same of this thought experiment, we'll say we've been working at it for a while and have managed to share enough about ourselves that we can communicate with language. We have for instance discovered that they are on a planet that also has gravity and so they can understand what we mean by up and down. Their planet also has magnetic poles so we can communicate north and south. Their planet also spins so we can communicate traveling in the same direction as the spin or the reverse direction of the spin, and that we call that going east and west. We through some more complex descriptions could explain our concept of right and left to them. But here is the problem, there doesn't seem to be a way to communicate clockwise or counterclockwise to them. If they are on a planet that spins in the reverse direction of us, our descriptions of our planet would still make sense, but they would, unfortunately, mirror everything. If they drew a picture of what they thought a human looked like based on our description of ourselves, they might equally likely draw the heart on the right or the left side of the drawing. They would just think that the side they drew it on was the left side based on their best understanding of what we could communicate with them. And with these other symmetries talked about in this video, if we weren't even positive the dimension we were communicating with, we would have confusion with these other issues. So the fact that there are ways for particles to break symmetry in some ways but not others is a GREAT thing. Because this means in our communications with this race we could find orientation we have compared to each other. IE: You do this experiment and we'll do the same experiment. If we get the same results we have the same orientation. If we get reverse results we have opposite orientation and just need to keep that in mind for future communications.

at 3:11 regarding the direction of spin: I'm not a physicist, but doesn't this illustrate the spin being counter-clockwise from the perspective of mirror-world? I feel like observer perspective is probably an important piece of this thought experiment.

I have listened to every episode of "Daniel & Jorge Explain the Universe" and yet only from this 3.5 year old video can I now put a face to the voice!

Hi, science fiction nerd here. A question that is more than likely being asked by quite a few people: If CPT symmetry were proven to be violated, would that not be proof that time travel is possible? Genuinely curious about this. Just seems like those two things would go hand in hand. Feel free to tell me if I'm wrong.

I wish I could go back in time and pay attention in my high school physics classes.

Meh, high school physics is terribly taught and presented. It's extremely difficult to do well on high school physics exams using just high school knowledge, because they make the matter unnecessarily complicated. Undergrad physics covers most of the same material generally, but does it in a much better way. If you have the calculus, the Feynman Lectures are perfect for this, and are available online. Else, you could always get a freshman non-calculus textbook.

I had a perfect score in high school physics, doesn't mean I remember much after all these years. So if you want to know what is going on today your best bet is to learn it today.

Me too.

Einstein was very clear on his theory of relativity, time seems to move forward to us when in reality time is non directional, hard to comprehend when seen within the human limitations

“The laws of physics shouldn’t care. They should work exactly the same in the mirror world as they do in real life.” Illuso: *laughs*

Your post just made me realize that law of physics working differently in the mirror world sound like a good idea for ANY movie haha

jojo referemce

URGENT Semantic Complaint: At 7:12 both sequences are actually symmetrical about a dimension of time, if you were to treat 'time symmetry' consistently as with symmetry for any other dimensions (has a negative and positive direction from a starting point). The 'Rewind' sequence is symmetrical to the positive progression through time if you consider that the time axis is flipped if you were to actually rewind time. I think better semantics for what is being described as 'Breaking Time Symmetry' is something like: 'Event Duration Asymmetry' Because one event is taking longer than the other in the SAME direction of time.

This is why science is so great! If a religious scholar finds evidence to disprove a fundamental part of a religion, the religion shuns them and holds on to their beliefs. If a scientist finds evidence to disprove a fundamental part of scientific theory, other scientists verify the findings, and give the scientist a pat on the back, a Nobel prize and adjust the scientific model accordingly. Beautiful.

One simple example of breaking time symmetry is polarized light. Experiment with polariser could be used to tell difference in which direction movie is played. Or just intensity of light reflected from water or glass.

Particle man, particle man. Doing the things a particle can

Particles are abstract models of physical phenomena. If experimental results don't fit the model then they usually just invent more particles, even virtual ones, just to keep the models going.

"It violates parity as much as possible" I think whoever set the universe up made it this way, and was placing bets with his friends about when will we notice it,

Sasszem there is a theory about this. I forgot the name but it states that once someone figures out how the universe works completely, the universe instantly resets and becomes more complex. It is possible this has already happened.

@The M25 or it's safe to say that when we die we'll get to know about it all ..

@The M25 but again that kills the interest and speaks out to us "Stay in your limits pathetic human"

@The M25 sounds like Douglas Adams to me. He figured it out, nec minnit...

@veristasium i think there is still a problem which may mislead to wrong data. From what I have been doing in maths, I thing there is something beyond infinity, a variable which mostly comes out to be equal to 1. I am 13-year old and had this doubt.

I imagine there's more involved in the parity symmetry debunking, but how do we know that the beta particles being released don't just move opposite of the "direction" of spin? Although the particles would be released in the z+ and z- directions in their world, it would only prefer it's local direction of spin.

good question

If There is Enough Time, The Balls will Somehow Get a Chance to Clump For a Few Seconds. The Only Issue is that Its Very Rare for All the Balls to Follow the Right way Without Hitting Each Other. So The 2nd Rule Can Be Breaked, But the Chances of it Happening are VERY rare.

Awesome video. Loved it. Great quality and very nice editing. Time is just one of the dimensions, not the Key to anything. As we are designed/evolved to think in terms of Time, it is extremely hard for us to think otherwise. If we could, we'd see the X, Y, Z, Time, Magnetic, Electric, Gravitic et al dimensional relationships very much differently, and Observe the Universe's marvels very differently. I tried and it sent me nuts for about a year before Beer saved my insanity.

0:25 Yeah, I feel like people, including scientists tend to forget that it is just a statistical principle.

Maybe time does not go in direction, but actually goes in both directions. But it goes in direction faster then in the other. Just imagine you do two steps forwards and step backwards, all in exactly same space of time. Effectively you go footrests and nobody notices you ever made step backwards. Maybe this is what is happening. It would very hard to impossible to measure, if it is what is happening, as you are left only with effective vector of time.

Everytime something's discovered, it destroys a ton of things with it😂

damn thats actually deep tho

“It is just an illusion here on Earth that one moment follows another one, like beads on a string, and that once a moment is gone, it is gone forever.” ― Kurt Vonnegut

Could it be that there is possibility in this ball thing, that particles that bounce end up in other corner exactly the way as it is in start? And maybe there is chance that forces of these balls moving keeps them in that starting pattern (indefinitely), just at other corner? And there is chance that ball thing becomes so that we cannot be sure without knowing which is starting point? To create this, balls should have similar (exact way is possible too, but mirrored or identical if the balls return to starting corner) way to get to that corner which is possible.

imagine breaking the symmetry and literally throwing the two best theories collected and experimented and proven through over 100 years with many scientists contributing their lives to prove and build on them. lol

You just explained Inception and Tenet in single video! 🙌

Sorry but can someone explain how a simple case of irregularly timed action (in this case, quark swapping) being played in reverse breaks time symmetry? It wasn’t explained very well in the video. If I were to film myself flipping a card over at irregular times and then play it back did I demonstrate a violation of time symmetry simply by noting that the timing of the flips doesn’t sync up backwards the same way as going forwards? That’s kinda how the explanation in the video made it sound.

If time could move both directions, it would make me question free will.

It’s a bit frustrating knowing these theories are incomplete. We can only hope to experience the day when someone discovers something enlightening and develops an accurate theory to explain what we already know and also what we don’t know.