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The pi/4 polyhedron

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Henry Segerman

Henry Segerman

Күн бұрын

Matthias Goerner's 3D print: shpws.me/SZbN
Countdown d24: • From Sphericons to Cou...
Matthias' version of the construction of the polyhedron: www.unhyperboli...
Demonstration of the Wallace-Bolyai-Gerwien theorem by Dima Smirnov and Zivvy Epstein: dmsm.github.io...
Brooks and Matelski were the first to make an image of what we now call the Mandelbrot set. This image is in the public domain: en.wikipedia.o...
According to Wikipedia, Pingala studied the relations between the numbers in what we now call Pascal's triangle, but the first appearance of these numbers arranged in a triangle was due to the Persian mathematician Al-Karaji (953-1029).

Пікірлер: 235
@aditya95sriram
@aditya95sriram 2 жыл бұрын
Segerman rule: "We shouldn't be naming things after people"
@henryseg
@henryseg 2 жыл бұрын
This is known as "Sriram's Joke", despite the fact that Joseph Young originally made this joke in this comment section 11 days ago.
@royflowers99
@royflowers99 Жыл бұрын
Called out
@asheep7797
@asheep7797 2 ай бұрын
@@henrysegthis is an example of Cunningham's law, where the person that a law is named after, is not the person who made the law.
@f.u.m.o.5669
@f.u.m.o.5669 Ай бұрын
​@@asheep7797 Alright, who made that law
@alan2here
@alan2here 2 жыл бұрын
Maybe as we keep getting better at studying history, we gradually push back the dates of discoveries, until we discover that it was Euler after all.
@jek__
@jek__ Жыл бұрын
Euler is just Euclid reincarnated
@gatergates8813
@gatergates8813 Жыл бұрын
I get the feeling the Mesopotamians (and even the pre-Mesopotamians) knew a lot more math than we give them credit for
@caspermadlener4191
@caspermadlener4191 2 ай бұрын
Basically all of Euler's work is known and available, this is impossible. Also note there is no reason for Euler to be unique, but comparing mathematicians is lame and pointless.
@Rubrickety
@Rubrickety 2 жыл бұрын
Very nice! You might leave some people wondering what pi has to do with it, since you only refer to the actual angles in degrees, not radians. Perhaps it’s worth adding a note about that in the description?
@henryseg
@henryseg 2 жыл бұрын
Ah, I didn’t realize that I never used radians apart from in the name… I think though that most of my audience knows that pi/4 radians is 45 degrees!
@MrRyanroberson1
@MrRyanroberson1 2 жыл бұрын
in a brief flash at 6:25 it's implied that the number inside the cos(...) is the same angle that he just uttered, which was "45 degrees" in speech and pi/4 in text, but this connection is not obvious to someone who doesn't know about radians at least
@jjaapp18
@jjaapp18 2 жыл бұрын
@@henryseg Assuming something about an internet audience is highly irresponsible, honestly. You should always structure your videos so that you can welcome people who aren't part of you regular audience. Explaining simple things like pi over 4 may be be silly for you, but it helps those watching you who don't actually know it and want to learn.
@BeaDSM
@BeaDSM Жыл бұрын
@@jjaapp18 "highly irresponsible"? Dude's just out here making the videos he wants to make; he doesn't owe us anything.
@jjaapp18
@jjaapp18 Жыл бұрын
@@BeaDSM The fact you're defending ignorance shows you yourself are usually just as ignorant. Don't side with insensitivity.
@kawzmOS
@kawzmOS 2 жыл бұрын
+1 for naming concepts after what they are and not who "discovered" them. I have also shared this view privately, and it made me quite happy to know I am not alone. This has impacts on professional and academic communication efficiency. A lot can be implied by the name of something. When you name concepts after people, you destroy an opportunity for expedient understanding despite little background.
@bluesillybeard
@bluesillybeard 2 жыл бұрын
I think that's why a lot of people use "cosine" or "sine" or "wave" transform instead of Fourier transform, since it more accurately represents what it actually is.
@locallyringedspace3190
@locallyringedspace3190 2 жыл бұрын
@@bluesillybeard ​ What are you even saying? The unit circle is a basic geometric object and its trigonometry has been understood since antiquity.. MILLENNIA before Fourier, Pontryagin, or anyone else studied L1 functions - S1 symmetries - or LCA groups in there revealing generality. Maybe sin and cos should be named after some great ancient geometer! For what reason not? In any case, their etymology is divorced from modern English; beyond the (inaccurate) usage of co- for ‘dual.’ The mathematics behind a formal definition, or theorem, speaks for itself. No matter what goofy name someone thinks is the most intuitive thing to call it. We might as well pay respects to the giants who’s shoulders we stand on.
@RozarSmacco
@RozarSmacco Жыл бұрын
Think how cumbersome it would be to name things as a description of the idea itself? For example “decaying exponential kernel infinite integral” for “Laplace Transform” You usually thoroughly think things through why not this idea?
@davidkim6673
@davidkim6673 Жыл бұрын
@@RozarSmacco Well, we'll usually just shorten the term into DEKII, which is now much easier to pronounce and remember. Imagine just saying, 'oh you have to do this differential equation, maybe you can just DEKII it'. It could catch on.
@WarofThoughts
@WarofThoughts Жыл бұрын
@@RozarSmacco It's all a part of the program described Noel Ignatiev who said, "Make no mistake about it: we intend to keep bashing the dead white males, and the live ones, and the females too, until the social construct known as 'the white race' is destroyed-not 'deconstructed' but destroyed."
@Tumbolisu
@Tumbolisu 2 жыл бұрын
Something I want to add to the naming comment: Even when something isn't named after a person, there is no guarantee that the official name is at all descriptive of the thing. An example would be the "k-D tree" data-structure in programming. The literal name means "a tree of dimension k", which could be seen to be a blanket term for things such as quadtrees (a 2D tree), octrees (the 3D variant of quadtrees), and as a third example, all dimensions of binary-space-partitioning. In actuallity, the name "k-D tree" actually refers to one very specific construction of a tree structure, and no others. My suggestion for a name that would be more descriptive of what it actually is would be something like "median-split tree". (Quadtrees and octress are very similar and would be in the category of "average-split tree".)
@MagicGonads
@MagicGonads Жыл бұрын
I think naming things after people actually *solves* a few problems, because some things have properties that we don't understand clearly, or can't clearly be conveyed in a simple term, or the connections it has to other, subtly different things, are so far unknown, but absolutely still need an unambiguous name, and it turns out if you name things after their properties that can often be ambiguous. (however, it's also easy to name multiple things after the same person- choose another name that's still a name involved with the concept but not a description)
@Anikin3-
@Anikin3- Ай бұрын
naming something after someone is fine because it is just that, a name
@akaritsukimi143
@akaritsukimi143 Жыл бұрын
Personally I actually do like things being named after people. Math is, by its nature devoid of any human fingerprints in the content itself, that is why I study mathematics. However for the names of the theorems and structures in mathematics, I like them reminders that the we are the ones studying it. As for misnaming I would prefer naming things by who first discovered them. I however would still argue that having it named after any person gets you to think about where the theorem came from more than naming it after no one at all. Ultimately though I think if we are gonna talk about recategorizing things we are gonna have to start with the notation for trig functions long before renaming theorems.
@rubixtheslime
@rubixtheslime 11 ай бұрын
also: "real" numbers, and the large quantities of normal/regular/etc things
@Rubrickety
@Rubrickety 2 жыл бұрын
Is it known whether this is the "simplest" such polyhedron? Or could one perhaps be constructed with, e.g., fewer total edges? (I would imagine proving such a thing might be extremely difficult, but maybe there's an interesting lower bound?)
@henryseg
@henryseg 2 жыл бұрын
I don't think anyone has thought about what the simplest version of this is. I know that Matthias had to make things a bit more complicated to get something that would 3D print. I imagine that Sydler put some thought into the construction - making sure that there wasn't a really easy way to do it.
@callumvlex7059
@callumvlex7059 2 жыл бұрын
"As long as it's cosine is an algebraic number" is a lovely restraint, it sounds scary to someone who's never done this kind of thing, but a bit of familiarity and it tells you the why, before you figure out the what.
@Juksemakeren
@Juksemakeren Жыл бұрын
its
@callumvlex7059
@callumvlex7059 Жыл бұрын
@@Juksemakeren Ah yes, ten months ago my autocorrect was wrong.
@Juksemakeren
@Juksemakeren Жыл бұрын
@@callumvlex7059 sure - blame it on the machine
@callumvlex7059
@callumvlex7059 Жыл бұрын
@@Juksemakeren I don't know why something this petty is so important to you, even if it was a human error, it was also ten months ago, dregding that up is a curious thing to .
@Juksemakeren
@Juksemakeren Жыл бұрын
@@callumvlex7059 k
@thromboid
@thromboid 2 жыл бұрын
Stigler's Law of Eponymy states that no scientific discovery is named after its original discoverer. (Naturally, Stigler credits Robert K. Merton with its discovery.) :)
@Garbaz
@Garbaz 2 жыл бұрын
Great point about the naming of things in mathematics. I'm glad that in modern computer science at least, we seem to mostly have done away with the practice. Instead everything gets given whimsical acronyms, which at least in theory stand from some more descriptive name.
@adamvolkinshtein1184
@adamvolkinshtein1184 2 жыл бұрын
Thank you for taking a stand and showing an opinion for naming in mathematics.
@ZenoRogue
@ZenoRogue 2 жыл бұрын
And Poincaré model, Klein model and half-plane model were all discovered by Beltrami... I do not like when a name is attached to something obvious, Voronoi diagrams are a good example. There seems to be a bias against people with hard-to-pronounce names (whether they are white or not), like the Zorn lemma, more accurately called Kuratowski-Zorn lemma. (In general there is some bias against Slavic people which is rarely talked about because they are white.)
@alquinn8576
@alquinn8576 2 жыл бұрын
and the airplane was invented by Russian genius Alexander Mozhaysky
@davideizzo2683
@davideizzo2683 2 жыл бұрын
to be fair, slavic names are hard to pronounce to everybody who can't speak a slavic language
@petros_adamopoulos
@petros_adamopoulos 2 жыл бұрын
@@davideizzo2683 Exactly the same can be said with "everybody" and "Slavic" reversed, can't it? Unless literally everybody speaks English, which I am not aware of it being the case.
@davideizzo2683
@davideizzo2683 Жыл бұрын
@@petros_adamopoulos I was just pointing out how phonetically unique slavic names and languages are, no ill intent
@pwhqngl0evzeg7z37
@pwhqngl0evzeg7z37 Жыл бұрын
@@davideizzo2683 In my opinion Slavic names are easy, and I only know English, and a little Spanish and German. The hard part is mapping the spelling to sounds, which I've found consistent. The hard part is if you know the sound but can't make it.
@bryanbischof4351
@bryanbischof4351 2 жыл бұрын
Love this style of content. Ty. Also great aside.
@StephenLindholm
@StephenLindholm 2 ай бұрын
Woof, so sorry I missed this video until Matt Parker's video today!
@Erin-ks4jp
@Erin-ks4jp 2 жыл бұрын
Naming stuff after people has it's problems as you point out, but like... mathematicians are rather uncreative. If you don't put a name on it it's all "normal", "regular", "perfect", and "simple". And when we are creative, the names are often just bad - there is some compromise between not using the same 5 or 6 adjectives and being unhelpful and irrelevant. I'm not sure names are that compromise, but they're at least a decent approximation.
@henryseg
@henryseg 2 жыл бұрын
The obvious solution is to encourage mathematicians to spend the time thinking about good, descriptive, not-over-used words to describe their objects. This is part of writing well, which is (should be) an integral part of being a mathematician.
@Erin-ks4jp
@Erin-ks4jp 2 жыл бұрын
@@henryseg Indeed - and it's a part of being a mathematician that is sorely neglected. Writing well is hard, and pretty orthogonal to most of the actual mathematics - but it's still important. What use is an insight if it cannot be shared?
@TheXanderLex
@TheXanderLex 2 жыл бұрын
Love the aside about naming conventions in Mathematics. This has long been a pet peeve, instilled in me by the late Ken Pledger, a phenomenal educator and geometer. More meaningful names please!
@heartles_xyz
@heartles_xyz 2 жыл бұрын
great video and thank you for the tangent into naming, it means a lot to see this brought up
@gucker
@gucker 2 жыл бұрын
I completely agree with you on naming. I find it ridiculous that commutative groups are called abelian, however there are no abelian monoids or rings :) Thank you for the video!
@mekkler
@mekkler Жыл бұрын
I also agree with the descriptive naming convention. This is why I say centigrade instead of Celsius (another dead white guy).
@Hogscraper
@Hogscraper Жыл бұрын
@@mekkler Unless you're a racist why would the race of the person even enter your mind?
@nicreven
@nicreven Жыл бұрын
@@Hogscraper since, by the looks of things (in terms of who has published works, and who things are named after), science as a whole seems to have been done EXCLUSIVELY by white European men. So it's just sort of like, saying Celsius continues that, while saying centigrade sort of separates the two, I guess.
@JNCressey
@JNCressey Жыл бұрын
@@mekkler, what would we call Fahrenheit? "Octoginticentigrade with duotriginti-offset" ?
@LeoStaley
@LeoStaley 2 жыл бұрын
Numberphile has a great video on the Dehn invariant.
@reddcube
@reddcube 2 ай бұрын
Robin Houston saw this video and thought, "I could do better."
@cheyneanderson4875
@cheyneanderson4875 2 жыл бұрын
"We shouldn't really be naming things after people" THANK YOU
@threepe0
@threepe0 2 жыл бұрын
Our name is one of the very few legacies we leave behind. If someone doesn’t have kids, this is more likely to be important to them. If you want to make a discovery and name it something random, go for it. I get that the history of this is troubled, but the mental yoga people do to satisfy their moral itches is tiring and usually pointless
@TheWorldBelow360
@TheWorldBelow360 Жыл бұрын
Good. Now build a performance hall in that shape.
@sinom
@sinom 2 ай бұрын
Funny thing being "Dehn" is German for stretchinf. So "Dehn invariance" sounds like invariance under stretching
@143685753ton22y
@143685753ton22y 2 ай бұрын
this is so fascinating
@michaelboyd8546
@michaelboyd8546 Жыл бұрын
Great video! Was glad to see you're a guest speaker for my college's math department on Friday
@prdoyle
@prdoyle 2 ай бұрын
I think if we stop naming things after people, that does more harm than good. The core problem is the naming bias, not the practice itself. Trying to give names like the "length-angle invariant" will inevitably become ambiguous when additional such invariants are discovered, and they'll also invariably lead to proliferation of acronyms, which suck. I'm also not a believer that the person's name necessarily always needs to be the very first person who discovered a concept. If someone else did important work studying, expanding, or popularizing it, that can be as important as the initial discovery.
@bigbluebuttonman1137
@bigbluebuttonman1137 10 ай бұрын
"We shouldn't be naming things after people." Yes, in "The Math Book" by Clifford A Pickover, a good third of the chapters are theorems named after mathematicians. And they never have easy names. But if these theorems had been named with their essence in mind--as difficult as that'd eventually become--it'd make remembering that stuff by name much easier.
@dfailsthemost
@dfailsthemost Жыл бұрын
Totally thought that was meant to be a time signature in the thumbnail. Simultaneously relieved and disappointed.
@Merakimeleka
@Merakimeleka 11 ай бұрын
I just searched for Pingala and I'm mesmerized
@nemesisurvivorleon
@nemesisurvivorleon Жыл бұрын
Gonna put random numbers on a random rock and call it an irregular polyhedron of chaos
@shadowofthenight7316
@shadowofthenight7316 Жыл бұрын
This was all over the place
@mattuiop
@mattuiop 2 жыл бұрын
Correction, we didn't have the "Privilege", we were just naturally good at it.
@hvok99
@hvok99 2 жыл бұрын
When I think about why you would want a shape that has 90° angles, what comes to mind is the ability to stack the shapes together, that is fill or tile space. While the shape and the techniques used to create it are pretty cool, I am wondering if there are other properties the shape inherits because of its angle uniformity? Very nice point about the problems with naming theorms after people. You could imagine that mathematics, of all disciplines, would relish a systematic naming convention for mathematical theorems, objects, and procedures.
@MagicGonads
@MagicGonads Жыл бұрын
I think this is because other fields have a narrower scope, mathematics concerns all sorts of concepts and creating a scheme to name them is a form of mathematics in and of itself, which you can find ambiguity in choosing the best one of just like all sorts of ways to view the same problem in mathematics. Look at the schism between different foundations, equivalences between different theories etc. to try to name them in a way that both would agree on requires agreeing on a further meta-foundation that subsumes both, and that just can't be done for free, but on the other hand naming it a completely meaningless- but still memorable name sidesteps that issue.
@toniokettner4821
@toniokettner4821 Жыл бұрын
is there any discovery of an even simpler shape with the same property? it seems like the second version is still not the simplest possible.
@angelorf
@angelorf Жыл бұрын
You should show the process by which that 3D shape is cut from some other shape. Now the video feels more like magic than like an explanation.
@MattMcIrvin
@MattMcIrvin 2 жыл бұрын
I was briefly confused by your claim that if all the angles at the edges were rational multiples of pi, the polyhedron had zero Dehn invariant, because I was thinking of the angles at the vertices of the faces rather than the dihedral angle between faces. For the cube these angles are the same, but for the regular tetrahedron, for example, they are not.
@Merakimeleka
@Merakimeleka 11 ай бұрын
Yeah! Knowledge and science are not European exclusive!
@hnryjmes
@hnryjmes 2 жыл бұрын
In my opinion you make some of the best mathematics content on KZfaq. Thank you!
@kaljinx
@kaljinx 2 жыл бұрын
Did anyone else have the urge to bite it?
@WindsorMason
@WindsorMason 2 жыл бұрын
Thank you so much for adding the aside! I truly hope that it leads people to come up with much more descriptive names in the future. It really is a problem.
@robertseptim3579
@robertseptim3579 6 ай бұрын
Is this guy related to Kripparian? He even does the same heas movement when he talks to the camera
@AlperenK.
@AlperenK. 6 ай бұрын
What a beautiful video
@petemagnuson7357
@petemagnuson7357 2 жыл бұрын
6:15 is there a easy way to tell which cos(theta) will produce an algebraic result? My first guess is any rational theta will make it work, but what other cases are there? Just something I'm wondering about and don't know how to research myself
@kaboomgaming4255
@kaboomgaming4255 2 жыл бұрын
I believe it's just theta can be any rational number or any rational number times pi
@lorenzoguerra3377
@lorenzoguerra3377 2 жыл бұрын
Every rational angle (in degrees) has algebraic sine and cosine, but the converse is not true. Look up Niven's theorem, for example.
@blinded6502
@blinded6502 2 жыл бұрын
Yeah, I hope that someday in a thousand years we'll completely rework the way we name and systemize things. No more random mathematical jargon for things that can be explained using common vocalubary. Electrons could be assigned a positive sign, so that current would be codirectional with flow of electrons. Measurement systems could be based on fundamental constants right from the start. Numeric system could be changed to HEX, since powers of 2 are more fundamental than some random number (10 in our case), and computers love them (and computers will be our best friends for eons to come, after all). Musical notation could use actual numbers, that specify frequencies and ratios between frequencies. Color theory could be simplified to a small handful of terms. And etc, etc, etc. There's just so many irritating tiny little things that accumulated over the centuries, which we can't bring ourselves to rework, since that would lead to even more confusion. And even if we rework those now, it might turn out it all was premature and could made things even worse. Just want to polish everything that we know, by remaking it fundamentally from the ground up, you know. Refactoring of all existing human knowledge, in other words.
@Tumbolisu
@Tumbolisu 2 жыл бұрын
Speaking of premature decisions, I think that using a power of 2 as a number base would not be a good idea at all. My 2 main arguments for this are as follows: 1. Base 6 actually has the nicest representations of simple fractions that I have ever seen. a half is 0.3, a third is 0.2, a fourth is 0.13, a fifth is 0.1111..., a sixth is 0.1, a seventh is 0.05050505... No numerical base with a power 2 can produce comparable results. Not even base 12 can compete. Base 10 is basically right in the middle. Watch "a better way to count", uploaded in 2018 by jan Misali, if you want to hear a bit more on this. 2. Powers of 2 are rarely the best answere to a problem, even when talking about computers. I will provide 2 examples. A simple example would be the sorting algorithm shellsort. When shellshort was first described, the author Donald Shell decided to use powers of 2 for determining the gap sizes at which numbers are sorted. Today we know that the powers of 2 are the worst sequence of numbers that anybody has ever used for shellsort. Most sequences that have been tried use the powers of 2 simply because of how easy they are to generate. The optimal sequence appears to be A102549: 1, 4, 10, 23, 57, 132, 301, 701, 1750 (with no further terms currently known). A more complex example comes from memory management in computers. This one is gonna be a story. First an explanation: When programers need memory, without knowing how much total memory they will actually need, they often use something called a "vector". Similar to an array, a vector holds a contigious piece of memory, but it can automatically expand its size when needed. For instance, when the vector currently has enough room for 8 elements, and you insert a 9th one, it will automatically move its content to a larger memory location. Traditionally, the new memory location will have twice the size as the old one, thus creating the powers of 2. Now for the problem: If you always double the size, you will never be able to reuse the old memory locations. The new location is forced to come after all the previous ones because it can not possibly fit in the old ones, assuming the first one was at the beginning of the computer's memory and there are no other programs running. Also note that the current memory needs to be copied to the new location before it can be reused, so this patch of memory is also out of the question. So, to be able to reuse old memory, you need a number sequence where the sum of f(i) from i=0 to n is greater than or equal to f(n+2). This is not the case for the powers of 2. For example, 1+2+4+8 is smaller than 32. (A memory of size 16 is currenlty in use, and the new one will be of size 32. Working backwards, the old memory was at most of size 1+2+4+8, which is not nearly enough.) If you were to only use multiplication with a constant, then the smallest factor you can increase f(n) by to get f(n+1) must be strictly smaller than the golden ratio. (Around 1.618) Software-engineers at facebook actually explored this problem. Many of their servers essentially have just a single, huge vector on them. They realized that a large portion of memory always remained unutilized, and so they started experimenting. In the end they chose to multiply the size of the new memory location by a factor of 1.5 (rounded down) and so managed to get more memory out of the same hardware.
@jugbrewer
@jugbrewer Жыл бұрын
i could see an architect taking inspiration from this form in the design of university building or something
@CaptainAwsome
@CaptainAwsome 2 жыл бұрын
what a rare sight these days. someone using the correct form of 'die' and 'dice'
@JNCressey
@JNCressey Жыл бұрын
Wherefore is "die" thought more correct to thee?
@CaptainAwsome
@CaptainAwsome Жыл бұрын
@@JNCressey die is the singular, dice is the plural
@JNCressey
@JNCressey Жыл бұрын
@@CaptainAwsome, dice is also singular.
@CaptainAwsome
@CaptainAwsome Жыл бұрын
@@JNCressey no it isnt
@JNCressey
@JNCressey Жыл бұрын
@@CaptainAwsome, why not?
@astropgn
@astropgn 2 жыл бұрын
That was very counter intuitive. I would imagine that if I had a tetrahedron ice cube mold and then melt the tetrahedron ice cube and use the same volume of melted water to make a cube, in my head that would be trivially possible. Apparently there is something that doesn't make it work, mathematically.
@henryseg
@henryseg 2 жыл бұрын
It would work, but reshaping water doesn't follow the same rules as cutting up into finitely many polyhedra and gluing them back together.
@482man
@482man Жыл бұрын
Loved the history aside, great work! My favourite bad naming in math is the Pythagorean Theorem since not only was it discoved thousands of years earlier is multiple places (Mesopotamia, India, China), it probaly wasnt even proven by Pythagoras or any of his followers for that matter
@sumdumbmick
@sumdumbmick 2 жыл бұрын
I'm completely fine w/ the Avogadro constant keeping his name, though, since it's an absurdly stupid thing, being the basis of a unit, despite just being a number, and at this point in history being a defined number with absolutely terrible properties. for instance, at the time it was defined to its current value there was only one perfect cube that fell within the error bars for the measured quantity. and, being a number that describes the number of physical particles of some substance you have it'd be really nice if it could be a number that could exactly describe the number of physical particles that can fill some basic shape, like say... oh, I don't know... maybe a fucking cube. but nope. the absolutely absurdly irrational love of base-10 came to the rescue and they just hacked off the number where it stood, leaving it with astonishingly horrendous properties. it's almost as bad as the Coulomb being a physically impossible amount of electric charge to have. wouldn't it be nice if there was a measurement system where the analogue to the Avogadro constant was both a nice number (like say, a perfect cube and an antiprime) AND it was the number that defined the analogue to the Coulomb? but, nah... metric is the best!
@_tybpxbzn_1042
@_tybpxbzn_1042 2 жыл бұрын
the density would change how much chemical could fit in a cube tho
@christopherking6129
@christopherking6129 2 жыл бұрын
I would like a video on the arccos of algebraic numbers polyhedra! Like how different degrees of algebraic number look.
@ElusiveCube
@ElusiveCube 2 жыл бұрын
Going back to Hilbert in his third listed of unsolved problems. We know a flat two D shape indeed can be cut up and rearranged in to the second, Is this possible say with a tetrahedron, can one be dissected and than rearranged in to the other. I know it can, because I have one at home, and am sure plenty of people know about it. Perhaps I did not understand the proposition correctly.
@kray3883
@kray3883 Жыл бұрын
Just don't confuse it with the Danish invariant, which has to do with the quality of the "free continental breakfast" at budget hotels. (Sorry, I had to do it.)
@deebznutz100
@deebznutz100 2 жыл бұрын
Melting and molding is the same as slicing in this context
@EnginAtik
@EnginAtik 2 жыл бұрын
I was hoping it would unfold to some pi shape made of 3 rectangular prisms.
@JoshBlasy
@JoshBlasy 2 жыл бұрын
I love your channel, and you deserve many more views. seconded on your aside as well
@thomassynths
@thomassynths 2 жыл бұрын
Your aside would be much better as its own video topic. Here it just feels like a forced jab to be honest and is lengthy enough to disrupt the flow of the lesson.
@keeb__
@keeb__ 2 жыл бұрын
If it weren't an aside people like you probably wouldn't click on it 🤷
@keeb__
@keeb__ 2 жыл бұрын
Another thing. Asides can exist on top of a separate video if you feel that the topic is important!
@petros_adamopoulos
@petros_adamopoulos 2 жыл бұрын
Poo points for mentioning race in a maths video, and assuming all white peoples (sic) were ever rich and able to indulge in research. I love the topic and my multiracial family.
@stumbling
@stumbling 2 жыл бұрын
I am in favour of changing names if there is evidence of historical precedence. I will be calling it Pingala's triangle from hereon out. Thanks.
@teamcyeborg
@teamcyeborg 2 жыл бұрын
Looks like it's been greebled
@seanoreilly849
@seanoreilly849 2 жыл бұрын
its all fun and games till the π/4 polyhedron starts boosting power to its weapons systems.
@radnukespeoplesminds
@radnukespeoplesminds 2 жыл бұрын
This feels like a meme. Is this still math or is this some form of geometric witchcraft?
@yakir11114
@yakir11114 2 жыл бұрын
great idea introducing racism and political theories like CRT to math videos. that will definatly end well and not ruin any fun.
@alquinn8576
@alquinn8576 2 жыл бұрын
yeah, this is youtube. if you want to virtue-signal, go to twitter
@jetison333
@jetison333 2 жыл бұрын
Hes correct, and its very evident that hes correct through.
@lumi2030
@lumi2030 2 жыл бұрын
interesting video, i liked the voice and narration as well. is this made for the summer math exposition #2?
@omerd602
@omerd602 2 жыл бұрын
Most likely not, Henry Segerman always makes content like this
@squidfeet7278
@squidfeet7278 2 жыл бұрын
this is so cool, thanks for sharing man!
@coneheadsilly
@coneheadsilly Жыл бұрын
i found this video, and the concept of this is really interesting! i go a 3D printer for christmas, so i'll be sure to check it out :)
@jek__
@jek__ Жыл бұрын
1/8th circle more like. lol A die is pretty much always practically convex unless the surface it's bouncing on is convex, as it only ever deals with flat surface physics. Though I guess there could be like a compression tension effect like if you threw a star on the ground the legs might spread and then elastically contract, flinging the object into the air 2:31 "for any two shapes with the same area you can redistribute the area and the areas will remain the same" uhhh... Is that a real theorem? lol. I believe that is what philosophers call "begging the question" wait, if you can't do this in 3d, does 3d calculus work? doesn't calculus rely on the idea that slicing something up more and more will probably lead it to a unit so small that any shape can be compared 1:1, even curved ones? If you can't cut a cube into infinitely small pieces and have them be able to be put into a regular tetrahedron, then you can't strictly compare their areas, as those areas are determined by counting similar units. Nonsimialr units can't be 1d-numerically compared
@dannydewario1550
@dannydewario1550 Жыл бұрын
Referring to your 3D calculus point, calculations are done using double and triple integrations which operate on single variables. In other words, 3D calculus is not necessarily "cutting across places" when finding volumes of curved objects, only across 1-dimensional lines. Also the Dehn Invariant is just talking about transforming shapes using finitely many cuts. I guess the concept of allowing for infinite cuts is where calculus kinda comes from, but the Dehn Invariant holds true if only a finite number of cuts is allowed.
@s4098429
@s4098429 2 жыл бұрын
The naming aside was vain and unnecessary. Maths is such a singular pursuit, it’s not unreasonable for the naming to be based on the discovers. For an individual to devote their time and unique genius to solving these problems is not a shallow display of ‘privilege’. Maths is not a talentless industry that can be filled with ornamental people just to comply with woke quotas. If maths becomes anything close to this, it will no longer be the mother of all sciences; it’ll be just another tribal drum circle. The people that make these discoveries are rare, they should be honoured, not race shamed.
@csasdwwewadwa9467
@csasdwwewadwa9467 2 жыл бұрын
Trust me, it is able to cut every 2d shape in existence and shape it in a square.. the problem is you have to cut it infinitely many times.
@Gisiebob
@Gisiebob Жыл бұрын
wait so are all the angles on the 'interior' also 90*? it's a little hard to tell just from observation (at least for me from just this video) and they are pretty tiny for using an auxiliary square angle
@henryseg
@henryseg Жыл бұрын
Yes, they are.
@just_a_dude75
@just_a_dude75 2 жыл бұрын
I love shapes!
@jonathantoothbreaker8786
@jonathantoothbreaker8786 Жыл бұрын
wait, arn't the angles at each edge of a cube 90 degrees too?
@KaliFissure
@KaliFissure 2 жыл бұрын
Our manifold Surface(cos(u/2)cos(v/2),cos(u/2)sin (v/2),sin(u)/2) 0>u>4π 0>v>2π. Notice that 4π, 2 full rotations, are needed to complete the surface. Electron half spin is an artifact of this topology. A single sided surface with catastrophic node > event horizon.
@jeremyashford2115
@jeremyashford2115 Жыл бұрын
The Pi/4 polyhedron is complex, but is it complicated, or is it simplified?
@EvilCherry3
@EvilCherry3 Жыл бұрын
Spends the whole video saying there's only one pi/4 angle and the rest is pi/2 while showing at least 3 parts of the shape that have an angle
@lexibyday9504
@lexibyday9504 Жыл бұрын
a Pifourhedron
@TheBetterGamer
@TheBetterGamer Жыл бұрын
welp, now i'm more confused than before i watched the video! oh well, i guess some ideas i just cannot grasp.
@FoxDog1080
@FoxDog1080 2 жыл бұрын
It looks like pyrite
@morkovija
@morkovija 2 жыл бұрын
ah, the secret cave of forbidden knowledge is discovered once again by us, the lucky few
@lazbn90
@lazbn90 2 жыл бұрын
About your Aside, at first you seem to be trying to make a fair point. It is true that some results in mathematics have been misnamed, so one is left with two main courses: do not let it happen again, and maybe trying to make justice to those cases in the past. Nowadays, by the structure of modern Academia, e.g the existence of MathSciNet, Arxiv, etc ... it is very hard for it to still happen. So, you are left with the question: can we do something about those old mathematicians who did not get the credit they deserved for those foundational results? Very unlikely, as this would imply at least to change every single basic textbook out there. So, although an almost worthless point to make, it is a fair one. But all of the sudden is not about people appropriating or being credited with other people's work, it's not even a racial approach to the discussion: it is specifically about white people appropriating non-white people results. This is TRIVIALLY not a racial problem, in most cases it was about influence, whether we are talking about a single person or a university. Furthermore, and not just talking about math but culture in general, whenever an empire invaded a region, they appropriated every single piece of information they could. This has absolutely nothing to do with race, but with power, whether it's military, economic, cultural etc ... Don't you think the Persians (non whites) appropriated all the Greek math when they conquered Greece (western European, hence whites)? What about when Egypt conquered Jerusalem (both non whites)? It's pointless to go on, as history is filled with examples like those. Even two out of the three examples you give, are white on white appropriation. This is a very lame excuse to vilify white culture, and in general, Western Society, by advertising your far left political views by virtue signaling how in tone are you with the "whites evil" trend. It's your channel, and although bringing up such a discussion doesn't seem to do it any favor, it's your choice. What I would expect from any rational person, is that at least you do it by trying to keep your political bias at bay, and in this case this was very easy to do, as I demonstrated above. It's also curious how this virus of obviating common sense and blindly seeking the mob's approval has spread even throughout the mathematical community, as noted in the comments so far, all validating your (I hope?) deliberate lack of critical thinking. For me, this is an automatic unsubscription.
@henryseg
@henryseg 2 жыл бұрын
It's not about appropriation - of course in the past when we humans didn't know better, every culture would name things according to how they learned about it, often incorrectly attributing. Of course our current culture is the same, although we are more aware of these issues and can try to improve matters. I'm not saying that white people are worse at this than anyone else - merely that where we are in history, the people who preceded us and named everything happen to have been mostly white men. None of what I said vilifies "white culture", unless you want to read it to do so. Here, I'll quote for you the entirety of the script that comments on white men: "You might get the impression from looking around at all the names of things that mathematics is only done by, and is only for dead white men. Of course in Western history, white men were pretty much the only people who had the privilege to be able to spend their lives doing mathematics." There are two sentences here. The first is a comment on the number of mathematical things named after white men, which I think is undeniable. The second is also just a statement of fact - in the past few centuries, the vast majority of people in Western culture who were doing mathematics were white men. Nobody else could be an academic mathematician - there were explicit barriers to entry that the few exceptions to the rule had to work around with great difficulty. (And the same was generally true at many other points in history, in many other cultures. Thankfully things are getting better here in the present day.) If you are taking any of this as an attack on your culture then you're reading more into it than is there. You seem to have missed the point of this section. I don't care about which culture gets the most science points for their team. I do care about people who may be discouraged from going into mathematics because the language of the subject includes only people who don't look like them.
@notmynamenotanyname6943
@notmynamenotanyname6943 2 жыл бұрын
@@henryseg Don't you think that the reason 'the vast majority of people in Western culture who were doing mathematics were white men' was because Western culture was primarily operated and inhabited by native Europeans? This 'universal oppression' pilpul targeting the dreaded 'white man' is jarring. Their were plenty of college-educated africans, arabs, asians, and semites in Europe and it's many colonies; where more colleges were located in the first place. I agree with the premise that names should be more utilitarian when it comes to mathematical concepts, but these were named out of honor in Western academia which publish these concepts for a greater body of researchers to look at and take part in. Men like 'Pingala' weren't (always) brushed aside, they just sunk into obscurity due to their location and language/culture barrier.
@dinoboyoutuification
@dinoboyoutuification 2 жыл бұрын
​@@henryseg "I do care about people who may be discouraged from going into mathematics because the language of the subject includes only people who don't look like them." "The first is a comment on the number of mathematical things named after white men, which I think is undeniable." It sounds explicitly like you are trying to say that things shouldn't be named after people, because of the fact that white people happen to have discovered a lot of mathematics, and that somehow, this is discouraging to people who aren't white? I don't know about you, but a significant portion of the classes I'm taking for my math major aren't being taught by white men, but in fact, all three of my math classes this semester are being taught by Taiwanese-Americans. My last calculus class was being taught by a man with a thick Nigerian accent. The problem of non-white people being discouraged from having a interest in mathematics due to some naming convention is ludicrous to me. There is no reason to specifically alter the names of known mathematical theorems, not when it adds confusion and difficulty for some agenda based on some hypothetical problem.
@freesk8
@freesk8 Жыл бұрын
The woke digression about naming inequity was not helpful. There is too much politics injected in to things these days. Can't we just discuss the mathematics, please?
@notmynamenotanyname6943
@notmynamenotanyname6943 2 жыл бұрын
>Watch math video to learn math >Get odd aside about white privilege bullshit
@rexwater1
@rexwater1 Жыл бұрын
I prefer names🎉😊
@KiR_Tank
@KiR_Tank 2 жыл бұрын
Amazing!
@ramonhamm3885
@ramonhamm3885 Жыл бұрын
Where can I find an online interactive scissors congruence website? Thanks! (yes, I searched) :)
@kevinbihari
@kevinbihari Жыл бұрын
The point about dane invariances was not convincing. Surely i can make 2 moulds, i square shaped and 1 tetrahedron shaped with equal volume, then fill 1 with gallium metal. Let it harden, break the mould, and use that metal made out of real independant phisical particles to fill up the tetrahedron or any shape for that matter. And there would be no difference between magically perfectly cutting 1 atom off and losely depositing it in the other shape (which the rules allow for. You said nothing about the cutting and with paper there are also parts that are lost in the real world but not in magic fairy math- is-2d-land) or melting off 1 atom at a time and depositing that. Do the latter one really fast and that is what you get when you melt it. The formations of dropplets has nothing to do with the vollume and is a downstream process from the melting solid and as such no longer contributes to that solid. If this is a problem to magic fairy math land than you can use vapour deposition and a hollow cathode tube to atomise individual atoms and recrystalisd them elswhere. It is like saying this piece of wood is brown. That chair is red. There is no way to turn brown into red, therefore there is no way to turn wood into a chair. Brilliant Simply fantastic Tremendous. Now, where is the practicallity of this. I know i am an idiot, but this is so far away from where my knowledge ends that i can not even start to comprehend the possibility of even devoting the energy to think about it. Just like an extinct hominin species would not know what to do with an ore of refined thorium and might be at most entertained by its shape or colour i have not the slightest fart of a beginning of comprehension why the thought of putting effort towards this even made sence to a person alive at the same time as me. But you do you
@zstolfi
@zstolfi 2 жыл бұрын
I think I'm stealing that overlay from now on, lol!
@decreasing_entropy3003
@decreasing_entropy3003 Жыл бұрын
I am too dumb to understand this.
@Tariqtalks1
@Tariqtalks1 2 жыл бұрын
Do you have any more examples of this in three dimensions?
@locallyringedspace3190
@locallyringedspace3190 2 жыл бұрын
Completely disagree. The canonical name should always be that of the discoverer. To say anything otherwise is antihuman.
@henryseg
@henryseg 2 жыл бұрын
The words in your username, "local", "ring", and "space", are all terms that are used to describe mathematical ideas and objects. None of them are named after people.
@alan2here
@alan2here 2 жыл бұрын
Famous non-wh…ite mathematicians (according to the internet): (edit: Ramanujan) Benjamin Banneker (1731-1806) Elbert Frank Cox (1895-1969) Dudley Weldon Woodard (1881-1965) Euphemia Lofton Haynes (1890-1980) Marjorie Lee Browne (1914-1979) David Blackwell (1919-2010) Jesse Ernest Wilkins Jr.
@henryseg
@henryseg 2 жыл бұрын
Al-Khwarizmi, presumably.
@SimonClarkstone
@SimonClarkstone 2 жыл бұрын
Srinivasa Ramanujan
@alan2here
@alan2here 2 жыл бұрын
@@SimonClarkstonegreat answer :)
@mbterabytesjc2036
@mbterabytesjc2036 2 жыл бұрын
I don't understand why the reference to "white men" was even made. I liked the suggestion of creating descriptive names for rules rather than using a person’s name, although this removes the honor of making the discovery from the person who did the work. Other than that I cannot condone adding 😕 the race comment to a scientific discussion. Who cares 😴 what race someone as long as they did and were credited, at the time of discovery, for the work.
@notmynamenotanyname6943
@notmynamenotanyname6943 2 жыл бұрын
@@mbterabytesjc2036 It's apparently hip to be extremely anti-white at all times. Childish.
@alienmoonstalker
@alienmoonstalker 2 жыл бұрын
There is a related video from Numberphile on how one can cut a polygon to make a different one: kzfaq.info/get/bejne/m7-Wo7Zy3a3Fm30.html
@telotawa
@telotawa 2 жыл бұрын
i 100% agree on not naming things after people, and calling them what they are. i wish some math version of IUPAC or something would organize and re-do all the terminology and symbols so that stuff made more sense
@minikawildflower
@minikawildflower Жыл бұрын
Absolute baller aside to address the problems with naming for old white dudes.❤
@michaw7408
@michaw7408 2 жыл бұрын
Fascinating subject, though you could spare that talk about white male privilege.
@alquinn8576
@alquinn8576 2 жыл бұрын
the woke mind-virus demands that such testimonials be made in all the dumbest places. struggle-sessions for all!
@seanoreilly849
@seanoreilly849 2 жыл бұрын
@@alquinn8576 the reactionary mind virus demands that the host go to the comments to cry about a 1 minute aside in a video that they dont have any rebuttal against. sad!
@alquinn8576
@alquinn8576 2 жыл бұрын
@@seanoreilly849 the meta-reactionary mind virus demands... well you get the point.
@igorshingelevich7627
@igorshingelevich7627 Жыл бұрын
Such a sharp edges mind! Like, subscr.
@deathzombee
@deathzombee 2 жыл бұрын
tau/8
@moffboffjoe
@moffboffjoe 2 жыл бұрын
Segerman's criticism
@asheep7797
@asheep7797 Жыл бұрын
Sriram's joke?
@qopdob
@qopdob 2 жыл бұрын
How many asides must a regular video have to be able to be rearranged into an A4 maths paper? (Nice aside, BTW.)
@aepokkvulpex
@aepokkvulpex 2 жыл бұрын
Props for the aside. I always knew you were a good dude
@goblinwizard735
@goblinwizard735 Жыл бұрын
“We shouldn’t name things after people” YES!
@FunctionallyLiteratePerson
@FunctionallyLiteratePerson 2 жыл бұрын
Love the aside here, good point @ the "only people with the privilege to do math," as well as not recognizing earlier developments simply because it's in a different culture.
@lyrimetacurl0
@lyrimetacurl0 2 жыл бұрын
For me that destroyed the video and channel. It was great until then, I would welcome renaming things (preferably so they aren't named after anyone). But to kick a dying race when it's already forced to be the lowest performing AND actively rejected for "diversity quotas" is beyond disgusting.
@brooksybaby03
@brooksybaby03 Жыл бұрын
​@@lyrimetacurl0 I finally found the comment I can agree with. Can't say I ever attributed a skin tone to the name of a theorem...
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