hi I'm Diana you're watching physics girl and I'm here with Zachary niceness who is the author and masterminds behind SMBC comics - Saturday morning breakfast cereal I've seen your comics like all over the internet and before I knew that they were yours I don't care this is pretty common to have this one comic that about a math teacher I'm surprised at how well bed because it was kind of me what was playing that was one where I got a whole lot of math each and I could I was surprised like math teachers who were still working we're like this is exactly it poor children thank you so much for the real reason that you're here yes to enter some physics riddles yes ok good ok I want to start with a warm-up which is more of like a physics trivia question good and I didn't get it right so good luck what are the base SI units I like the most fundamental yes cause here if you want to think about the answer first grams I want to give you the point for a gram there's actually a kilogram a kilogram is weirdly defined off of a physical object a cylinder kept in France called the big K meters obviously this is such an evil question for someone who hasn't studied physics for a long time because they're obviously all the bigger like aggregate units like the joules kind of fundamental no one is every seconds of course yes the second is defined off of the frequency of light from energy level transitions in a caesium 133 atom so weird and there's more okay well there must be a charge unit right so that's also one that I guess I thought the Coulomb was a basis I mean right I don't know why not it's probably a historical reason I did not you've gotten all the ones that I got and then the rest of them are weird what else do you need to describe what's going on in the universe we've got a practicing physicist over here like that dying answer do you know what is it I think yeah yeah that's one of the weird ones I never would get the Candela which has to do with like the light from a candle and yeah I am okay explain hands yeah it turns out the amplitude base unit for historical reasons it was historically easier to measure the force on wires with current than to measure individual charges and they'd be cooler they're not huh we should write a letter is ready falling about there yeah okay so there's yeah they're two more he was killed in yeah that was just the warmest to let you know how mean is with these riddles yes so the actual riddle is a real riddle there's a group of prisoners you want to pick a number hundred one hundred fifty of committee was a lot of crime the evil warden besides she wants to play a sadistic game and so she tells all the prisoners the night before the next day she's gonna line them up and put hats on them one of two colors doing picked colors Oh purple and green Waveland green you've got purple and green hats randomly on the prisoners it's going to be a random number per for green hands you don't have necessarily fifty purple and fifty green what she says to the prisoner she's going to do is line them up all facing the same direction for example the prisoner in the back is looking forward and can see all of the prisoners in front of him and then the next prisoner can see just all the ones offering him the prisoner at the front can only see the wall go so then she's going to go from the back and ask the prisoner the color of her hat if she guesses correctly she gets to live if she guesses incorrectly she dies a silent death and then she goes to the next prisoner imagine that I'm behind you okay and you're facing that way and the warden comes to me and like what color is your hat and I'm going to make my guess or my educated guess you like green that's all you hear and then I will either die or not but you won't know yeah and then you and you like you guys is there a strategy the prisoners can come up with to maximize the number of prisoners that are going to live so they can meet before like the night before but they can't like look at each other's head and say no she lines them up then puts the hats on of different colors they can't see their own hat they can only see the hats of the prisoners in front of them do they get to pick how they line up anyway they're just randomly and then randomly given huh and commit they can't interact after their window the only thing they can say is guess the color of their hat so they can talk to each other they can talk to each other to come up with a strategy the night before but not the day I'm not the hard one don't try and maximize the number of survivors not necessarily my right do you hear the person behind you when they go yes you do I mean yes the other you can do is guess the same thing or guess the opposite thing but I don't see how that you can see your house oh okay so you should always guess what the next person is going to say to only one person that is right well thank you laughing everyone can see all of the hats right right so the next person who's going to be up you should just say whatever their head is then how many designers be like the strategy your thing right is like you say the Hat of the person in front of you say it's like green purple green purple green purple and everybody dies if you just say the Hat in front oh right of course because they could I think it's been great thing exactly I said yeah you're right right yeah if you sign up free purple beautiful and then like every other person the worst loss for that one would be oh yeah but you can play it in a different pitch too till the next person whether you're lying in that that's me just read you wasn't banned by the rule the movement was that you're guys yeah they're kind of my cheating method so the first person who could say something about the total group with one word but like so you could the first person could say what the majority is the nothing like that or something like I went through this jungle silently in my room yeah right the hint for you did you figure out the thing that you could look for where in seeable group and decide something binary broke like either it's this or that group so I tortured Yunus physics trivia question and a really hard right on this do you want to ask me your riddle I'm suffering well that's a great idea okay yeah okay so this is this is a race mullion riddle look this is something I guess he did at a lecture he thought it was at a math lecture and called some poor guy up and he said I want to make a deal with you and the deal is I'm going to give you two $10 bills and then I'm going to make a statement of some kind just any kind of logical statement and the statement is false you give me back one of the $10 bills and the same is true you keep both so would you agree to this it's a good deal right you either get $10 or $20 and so the guy says yes and then he says okay and this is this is not the statement he says I'm going to say something and then you're going to owe me $1,000 and the question is what can I say it'll result in him being notice as knows the ramon's million will get $1,000 it's just the statement the other guy doesn't interact any more at this point but the other guy have a have $1,000 that's his problem you got to top it up looking me going today good now you're suffering too is it something like in order for you to figure out whether this statement is true you need to give me $900 in the sense that that's like a logic statement maybe that sort of structure but it's not that it's not even that complicated it's not even that complicated I feel like getting knowing is something like a qualifier where is it something like there you will keep ten dollars and give me back one thousand ten or he will keep $20 and give me back a thousand aplenty no because then you can just not do it and the state would be focusing you don't have to give back ten dollars yeah yeah fly in my own image yeah yeah yeah there's a condition where you can escape I think I think that I'm gonna all right look I've allotted I'm ready good answer yeah the answer is he will say you will either give me a thousand dollars or ten you have to think for saying about why this is true right so yeah so is he right - yeah I can't give them $10 he's in the statement song oh yeah I get it that's what I was trying to get was like there's something in the statement that guarantees that is either true or false right but you will give me ten dollars is what contradicts the statement right if it's ten dollars then it's false but then he is doing what's right is default as we - yeah I like that okay are you ready yes well the solution that guarantees the most survivors I have to do is even okay and the person in the back says purple that means there's an odd number of purple hats ahead okay and and the next person will know what they are so the person the back will say either green or purple and determine the total like of the rest of the Hat is there an odd number for blacks or an even number for Marcus and they're telling everybody that so then the next person can see the rest of the Hat and see you okay well damn it that's beautiful that's great yeah that's really good yeah so if you look down the line and you know it's odd and there's an equal number of the other kinds of pets you know you must give a odd man out the odd person out yeah if it's if it's not the you know you must align with the missing spot yeah so you have an answer to your actually that's really here say everything you and I both like got right up to that list thank you so much thank you very much this is such a coincidence I happen to be in London and go to Bob as well everyone laughing I have been fixing that wasn't that really I was so good about yeah BAM hey one last thing it's that time of year again necklace just kidding PBS Digital Studios are running a survey and basically they'd like to hear from you what you'd like to see more of on YouTube and in the world so it's a quick survey there's a link to the description and in the card and 25 random participants are going to get a PBS t-shirt so sounds worth it that's all thanks