Hi, I am a pure mathematician, working in the School of Mathematics and Statistics at UNSW, in Sydney Australia. This blog will touch on various thoughts on mathematics: ideas, patterns, surprises and some hopefully serious discussion on the weaknesses of modern mathematics, which ought to be more widely known and considered. And it will also have other occasional random thoughts, which are, at least in my mind, somewhat mathematical.

This is part of a large scale program I have to reorient mathematics towards a more sensible logical basis. Another aspect of that program is my YouTube channel, called Insights into Mathematics, which has more than 500 videos, 27,000 subscribers and 4 million views. The user name is njwildberger, so check out my channel for a lot more mathematics!

Here is a link to my UNSW web pages: My webpages

1. John

Thanks for pointing me to this web site. It is an excellent way to share your ideas with like-minded people.
John

2. Lawson Brouse

Mr. Wildberger,

I recently “discovered you” and I want to thank you very much your posts, you tube videos, and work have just made my life far more interesting. Thank you, sir.

Lawson Brouse

1. Aktham

Prof. Wildberger amazing lectures on AlgTopo,,, i wish i could have your handouts or your notes on ALGTOPo.

3. Kassey

Professor, I want to thank you for the wonderful insight you have given me in mathematics, I’m not a mathematical inclined person, but your YouTube lectures are starting to change my experience with mathematics. – I never thought I would enjoy mathematics. Thank you

1. Dan Burrell

Hi Norman.

I’m a high school mathematics teacher trained in applied mathematics and statistics as well as physics. My hobbies include looking into philosophy of mathematics and it’s foundations and have often wondered at the apparent divide between analysis and geometry/algebra/topology.
I’ve recently become quite interested in category theory/topics theory and the way it might provide a useful language for representing concepts in mathematics and how the notion of functoriality enables bridge building between seemingly disparate mathematical theories. I’m not sure how categorial notions figure into your thinking but I do detect a kinship of sorts between your views and the constructivist ideas that replace the Boolean algebraic bent of Z-F set theory with Heyting non-binary notions of ‘truth’, abandoning the axiom of choice, shattering the continuum and only recognising the potentially infinite as opposed to actual infinity. These are ideas that I’m still only beginning to grasp, not least because of the serious bias in published mathematics towards philosophy that accepts the infinite and hence irrational numbers as ‘real’ and not as convenient lies. Thanks so much for your work and for making it freely available.

2. Byron

Mathematics is very beautiful. Dr. Wildberger has influenced me greatly with his ability to bring out the splendor of geometry.

4. Carlos

Mr. Wildberger, mathematics is just a hobby for me but you poin of view clearly illuminated many paradoxes that i had about infinity. So i am not infinitally grateful but you can set the bound XD. I want to get the book but i want to know if there are any issues about shiping to mexico if i buy from pay pal? Thx once again.

5. ubi de feo

hi, Norman

I am thankful for accidentally bumping into your efforts in teaching math and geometry.
I love your approach, starting from the beginning and moving forward in a very pragmatical and interesting way: relating to things we can picture easily.
I follow the same approach when I teach programming and beginner’s electronics (you may find something searching for “from 0 to C”).
I had major issues in school because my teachers failed to make their subject more interesting than hacking on a Vespa’s engine.
thanks to your videos I’ve been able to pick up math again and now feel fairly comfortable with a lot of things beyond basics.
not long ago I realized that so many concepts in math which I failed to understand in school, are just algorithms and procedures I’ve been implementing in code for the past 25 years without knowing the math counterparts 😀

well, I just wanted to thank you.
I hope I’ll find the time to watch all your videos.
may take a while 🙂

cheers,
ubi de feo

Hello Prof.Wildberger,
I am a high school student and have been watching your videos since a year and a half.I followed your whole course on Universal Hyperbolic Geometry and linear algebra and am following the differential geometry one now.I had and am still having interest in geometry as a career and have been reading calculus books but when I started your youtube courses I have become a “worshipper” of rational trigonometry.I heartily agree with you that this kind of geometry is indeed the geometry of the future.Your courses and work in mathematics are excellent and your way of teaching is beautiful.Your posts on the real way of delivering mathematics education should recieve implementation as much as they are recieving an audience!
Thank you very much sir for uploading those courses on youtube!! I hope they really draw a greater worldwide crowd for developing the newly emerging geometry!!

Regards,

7. Omar

hey Prof.Wildberger, about three or four weeks ago I bumped into your youtube channel, and watched a couple of your videos, and they are amazing! I liked them a lot ! thank you for your great effort, and I wonder when you will post the third lecture of “the rotation problem and Hamilton’s discovery”, also if you could make a video about “brachistochrone problem” and it’s solution by Newton and Bernoulli that would be awesome, keep up the good work,

I am enthusiastic high school student.

1. njwildberger: tangential thoughts Post author

Hi, All four lectures on the rotation problem and Hamilton’s discovery are now up at my channel Insights into Mathematics on YouTube (user njwildberger). You might like to watch the lecture MathHistory14: Mechanics and Curves for info on the brachistochrone problem.

1. Omar

thank you prof, I’ve found it in the suggestions bar, but I noticed that part III and IV aren’t included in your (famous math problems) playlist.

8. Victor

Hi Prof. Wildberger, i am a college student from Brazil (Mathematics) and your ideas about the problems with angles and trigonometry are the same as mine. When i found out about the rational trigonometry of yours i was really excited and i’ve been watching many of your videos recently to help me out. I love your work, but i can’t found a way to get your book “Divine Proportions”, is there a way that you can help me? I want to learn more about it and present to the mathematicians here in Brazil. Thanks.
Victor.

1. njwildberger: tangential thoughts Post author

Hi Victor, Nice to hear from you, glad to hear you like RT. Information about my book is at the publishers: wildegg.com but for some reason the Payment system there is not working currently (something I need to fix but i am currently too busy!) So I suggest you get the book from Amazon.com.

9. Victor

Soon as a get my hands on your book, sir, i will !
Keep up the good work, your videos are helping me a lot, i am learning so much with you, thanks!

10. Jud Imhoff

Hello Professor,
Just want to join the group here in expressing gratitude for your efforts on the YouTube videos. I intend to watch them all and hope you make more.

I like your rejection of infinite sets and questioning of real numbers. It is interesting that Mathematicians haven’t yet been able to clearly understand and communicate the true nature of the continuum and reconcile what I believe is the natural occurrence of the ‘concept of infinity’ in Mathematics. Is it too complicated for Humans to get their minds around? Is there a different type of number perhaps an asymptotic numbers? Can rational numbers also be regarded as such in a certain context?

The ‘Real’ Numbers should be called the ‘Ideal’ Numbers and the Rational Numbers the Real Numbers because the Rational Numbers are the numbers we are in ‘reality’ constrained too as we try ever so hard to approximate the ‘Ideal’. Of course π doesn’t exist because a perfect ‘Ideal’ circle doesn’t exist. Nor for that matter a perfect point, line, length, area etc.

But this only means that the concept of infinity is embedded in our Mathematics, so how do we explain it? Don’t we need too?

Anyway, I’ll continue to watch your videos learn and scribble in my notepad. Wishing there were more great educators like yourself making similar outstanding contributions.

Thanks, Jud Imhoff

11. Naveed

Dear Professor Wildberger,

I am fascinated by the first half of your first lecture on Differential Geometry (which is all I have seen so far); you cleared up confusions I have had about conic sections for years, despite having studied and come across them over and over again! Also, shouldn’t quadrance be a standard term in regular use!

Can I ask you for a huge favour: Could you please post lecture notes and/or a set of problem sets to go with your Differential Geometry youtube lectures if you have them, or point me to a suitable resource?

Many Thanks,

Naveed

12. Thiago Carvalho

Hi Mr. Wildberger! I came across your blog today whilst searching for new mathematical ideas. I started studying mathematics about 2 years ago after watching documentaries about the universe including visionaries such as Seth Lloyd, Leonard Susskind, Edward Witten and Nick Bostrom. I’m looking forward to seeing more of your videos and participating in some of your discussions. I also have a Youtube channel and a maths website.

13. Byron

I recently came across Dr. Wildbergers lectures while searching out some of the info on triangle centers. He has a very high quality lecture style. Good pace, very easy to understand, brilliant, etc. I am now on a mission to watch every video on his YouTube channel and eagerly look forward to learning and enjoying your presentations. A heart felt thanks to Dr. Norman Wildberger for his enormous contribution to humanity.

14. Alex

Hello Dr. Wildberger,

Firstly, I would like to thank you for the tremendous contribution you have brought me and many other in making mathematics a bit more accessible to those of us with less of a natural orientation towards the subject, through your wonderful youtube channel; it has definitely made a number of concepts clearer for me and has also opened my mind to new ideas, such as the problems with real numbers and infinity.
Lately I have been trying to get my head around the Fourier Transform and its applications, mainly regarding various filtering operations (images in particular), as it I have intersected with the problem in both academic and personal endeavors. Although there are many implementations of various filtering operations available, I do not like using something that I don’t understand and I’m struggling with that part so far. I know that this is less of a pure mathematics subject and more inclined towards applied mathematics or engineering, but if you would enjoy covering this subject (and if time allows of course) I would really appreciate to see your approach on in (and I don’t think I would be the only one).
All the best,
Alex

15. Martijn van Eeden

Hi mr Wildberger,
Thanks for the inspiring lectures.
About your aversion for the “Real” numbers because they assume infinite actions.. (forgive me for my choice of words, but the point should be clear I guess) I completely agree. However… I think that the “Rational” family misses some essential values like pi, square roots, etc. Wouldn’t it be a good idea to introduce a new family which is defined by all values that we can geometrically construct with simple Euclidean tools: the “Constructibles” for example..
If I am wrong, please tell me why.. I would be eternally thankful.
Kind Regards,
Martijn

1. njwildberger: tangential thoughts Post author

Hi, It would certainly be worthwhile to develop such a more limited extension of rational numbers. The challenge is: how to do this in a logical and consistent fashion? It turns out to be much more difficult than one might suppose.

1. Martijn van Eeden

Maybe, … and this is certainly an uncristalized thought …., the weakness in the first place is the way we tend to write down values in a decimal system. If we would write down values as their true value, independent of the cipher-system, then the values like pi or SQR2 would not be infinite rows of decimals, but just one beautiful “symbol or mini drawing”, as would any rational number too.
So if indeed all true values , “constructible” values, are the values that we can construct with geometric tools, then we obtain all rational numbers and the “true extension to the rational numbers” as you could call it by applying geometry itself to describe numeric values.
So only using integers and operators, we could write down any true value exactly. I will try to work this thought out to a more concrete and practical one..

By the way, the interval story to avoid rational numbers in the “Real number” (minus the Rationals..!) is in my opinion not even a way to describe all missing “Real” numbers, because if you allow infinite repetitions of that process, then you are only describing infinitely small intervals and no single values. If you allow something left, then you allow it also on the right.. right?

16. njwildberger: tangential thoughts Post author

One of the key challenges to make things work logically is that either you have a single canonical way of representing a `number’, such as we do for natural numbers in the Hindu-Arabic system, or you have a well-defined range of different allowable symbols, with a clear notion of equality that allows you to tell if two symbols represent the same `number’, as we do for rational numbers.

17. Martijn van Eeden

In MF128 you are talking about the volume of polyhedrons, the Robbin’s formula and the Bellows conjecture etc. and probably the culinary inventor of tagliatella… who was of course in his time doing research on different shapes and volumes of pasta.. In the previous lectures you specifically mentioned all the time that the points of the polygons had to lay on a circle in order for the theorems to be valid. Shouldn’t then also not the points of the polyhedrons be on a sphere? Of course the classic polyhedrons with regular shapes are already compliant with that, but the irregular cube that you show halfway could be.. and could not be… it is not determined, at least not as far as I could get from your lecture..
Again thanks for your efforts to disclose all this wisdom to the world.

1. njwildberger: tangential thoughts Post author

We started off with Brahmagupta’s formula for a cyclic quadrilateral, but ultimately we are interested in general shapes. The point from a foundational point of view is that all the really good formulas are naturally in terms of quadrances, not distances, so they hold algebraically in considerably wider generality.

18. Martijn van Eeden

Dear mr Wildberger,
When I was a student some of my teachers loved me, and some of them could skin me alive, because I always questioned them and hit the nail on the head where it hurts the most. I hope that you will not skin me alive when I point out a “mistake” in your reasoning. (With all due respect of course, maybe the word mistake is to harsh, but as a pure scientist we should be hurt by a true statement…).
Lets go for example to the point in MF131 where you want to claim that you can not prove Ptolemy’s theorem by calculating √(4/5) x √(882/221) + √(162/65) x √(4/17) =? √(144/85) x √(50/13) to prove that ab + cd =? pq. I can perfectly do that without taking any square root of infinite complexity: try it yourself please: the numbers all cancel out before taking a square root and you will end up with the perfectly do-able: check if √49 + √9 =? 10.. Yes: 7 + 3 = 10!!!! so.. since you are urging us to carefully go through each step.. and I do… therefor I can tell you this.
So I would like to suggest a revising in the direction you are going:

Lets not avoid the existence of square roots. They do exist, only we can not determine their exact value, in other words, the root exist, but their exact decimal value does not exist!!

We can indeed not exactly determine the length of a line segment in a plane, yes, true, but we can still work with it because we can perform exact operations on them so that the result is rational again, and therefor exact..
Another thought is that as you also said yourself a line and a circle that intersect don’t have necessarily common point, because only rational points exist…., that implies that the lines are not continues, but “quantized”. The level of quantization would be infinite so maybe infinity is unavoidable unfortunately.., so. The fact that we can not exactly give the value of the coordinates in a decimal cipher system due to infinite row of decimals, is more due to our cipher system than the question whether the two meet. There meeting point could be described by equations.
So again, yes let us be precise and exact and logical. But we don’t need to avoid things that exist, we just need to learn how to work with them in an exact way.
Kind Regards,
Martijn.

1. mehdi s.

“in other words, the root exist, but their exact decimal value does not exist!!”
I think you didn’t get, that Dr Wildberger’s exact point, was to show that this kind of phrase, is utter nonsense. The harder to write down down complety one thing’s actual value, the more its very existence becomes questionable. And if it can not, even in theory, be written down completely, it doesn’t exist at all. So three’s squared root doesn’t exist, while squared root of two does. End of the story…

19. Martijn van Eeden

Here is a thought about an idea that has been discussed in your lectures.
First three Euclidean axioms:
1 : you can draw a straight line from any point to any other point.
2: you can extend a finite straight line continuously in a straight line.
3: a circle (in the plane) is all the points that are at a given distance from a given point (center).
So it already follows that straight lines are continuous and circles are not!

The statement of Mr. Wildberger that a unit circle and a line y=x do not meet at point [1/√2,1/√2], since this is no rational point, is therefor true since the circle has no valid point there, and does not even exist there!

But this also implies that if the circle is not continuous, then its curve is not “infinitely smooth” and therefor the area enclosed by the circle is at the edges purely bound by rational coordinates that according to Euclid connect with straight continuous finite lines.

That means that the enclosed area of a circle is a rational value and not a “irrational” value through π. Of course we have to go very deep here, but it is an essential point.

And it also means that the line y=x does pass through [1/√2,1/√2], since it is continuous. We simply cant call it a point, … we cant stop there …, since there is no point there. So lines fill in the “gaps” jumping instantly between two adjacent rational points.

20. Gary Richardson

Knowing your disdain for “real numbers” I thought I’d send you this video, in case you haven’t seen it.

Dear Dr. Wildberger,
My name is Ahmad Eid, I’m a software engineer and an assistant prof. at the Port-Said University, Egypt .I’ve been following your admirable work for a while now and I hope there comes a day soon where every engineer, scientist, and teacher can use your understanding of mathematics to deepen and expand useful knowledge. As I understand the motivation behind all your work is a deep feeling of inconsistency between our discrete physical reality and the imaginary continuum idea inherit in real numbers. I think your work would benefit if a solid philosophy is used as a basis for the mathematics. I recently came across the extraordinary work of R. Buckminster Fuller and I immediately felt the link between his work and your ideas. I recommend that you take the time to read the book “A Fuller Explanation: The Synergetic Geometry of R Buckminster Fuller” by Amy Edmondson. I think you will find it very interesting and I hope it can provide new solid directions for your work.

22. sag aro

Hello. I admire your relentless assault on trying to understand the underpinnings of the physical forms( that is what math is to me)
I am a curious person, like you, who wishes to know hidden secrets of the number universe. I am not formally trained, in fact I just simply figure out through deduction, in math. I work on reptends, period lengths of inverse numbers, repdigits and sequences. I was wondering if you have ever tried to figure out the hidden theories of that area of mathematics.
If you have I would like to talk to you about some of my findings in the hope that some of your knowledge can be assimilated to be used as a torch to help light some of the path I am exploring.
Cmre.sager@gmail.com

23. Luca

Hi Professor Wildberger,

I really appreciated and enjoyed your youtube lectures (Mathistory, Probability, Algebraic topology). I would like as you if are you planning to come out with an advanced probability video course or maybe something like stochastic process.

Thank you for your very very interesting videos.

Luca

24. Hyder Abbas Hussain

hi sir i am from pakistan student of undergraduate mathematics in ist year,i watch daily your youtube videos most helpful and providing guideline,our teacher gave us this problem i cant understand either its origin or not,how this can be solved 1)381865=027261,2)027261=720767,3)720767=162569,4)162569=714160 5)714160=? now what will be other number that will come?please tell me only one and equivalent equation for all these to solve,

25. John Reynolds

Hi Professor,I try to read as much of your work as possible,each topic on you tube videos is out of this world…Keep up the good work.I study maths at the O/U,but yours is a lot more interesting.
Kind regards

26. David.

Hi,

thanks for all you have been doing. I’m a physicist interested in learning algebraic topology and after some unsuccessful tries with a couple of books your channel have helped me a lot.

Regarding your algebraic topology videos. The last lesson is about homology and Betti numbers, but in the video you say there will be a next lesson about the topology of 3 dimensional objects. Is it available? I am very interested in continuing the course, if possible.

Thanks.

27. Jon

Throughout my study in Mathematics I have always tried to imagine the meaning from a Geometric Point of View. You are the only teacher that I have come across to express this beautiful and important interpretation. Thank you for sharing your knowledge. I would love to see the geometric connection in some other fields like differential and partial differential equations. I hope for many more video lectures!

28. Antone

Hi, I recently saw a video where you discussed Infinity and found that I agree with you on several of the key points you made. I have no formal training in mathematics or philosophy, but I have several informal proofs that I think you might find interesting–and perhaps even useful. For instance, I have an argument which I think conclusively demonstrates why Cantor’s strategy of 1-1-correspondence is not valid for determining when sets are the same size. I also have a theoretical framework for set theory that would make Russell’s paradox meaningless. I have a strategy for a proof that conclusively demonstrates that an infinite set which is larger than the set of irrational numbers can in fact be placed into a 1-1-correspondence with the counting numbers. A semi formal counter-proof for Cantor’s diagonal proof, which supposedly shows that the [set of counting numbers] and the [set of even counting numbers] are the same size, as well as a semi-formal counter-proof for his proof which supposedly shows that the irrational numbers is a ‘larger’ infinite set than the counting numbers.
The one place where I disagree with you is your insistence that infinity does not exist. Your argument for this would also seem to imply that astronomically large finite sets do not exist either, which seems odd and somewhat more difficult to defend than need be.
I agree that it cannot be actualized in a physical sense, but I think it clearly exist in a conceptual sense. Furthermore, I think the best strategy is not to rail against infinity as a whole, but to formulate a system that can accommodate both types of existence–and thus is able to keep infinity confined to the realm where it belongs. I believe I have a strategy for doing this in a would remain consistent, while getting rid of the continuum and many of the other difficulties in modern mathematical thought.

I would be very interested in discussing these ideas further, so I hope I have peaked your interest enough to try contacting me.

29. Ali

Dear Prof. Dr. Wildberger,

Words are not enough to express my gratitude to you for changing my life.

During my M.Sc. education in “Magnetic Resonance Imaging”, I realized that all the branches of science are meaningless without “Mathematics”. After sometime, I felt a great need to learn it deeply from a historical point of view and looked for a professor throughout my country to participate in his/her class, but I unfortunately found no one.

Eventually, I searched the internet and found your channel in YouTube. It was great; it changed my life so that I have decided to continue my education in Math. I hope that I find a university letting a medical practitioner (me) to study Math in higher education. I feel a great peace by it. I really don’t know how to thank you.

Yours sincerely,
Ali

30. Paras Mahajan

What is the reason behind writing the symbol for the unit of area i.e. square meter, as m^2?

What I mean to say is as follows:
Measuring the area of a surface is determining its ratio to a chosen surface called the unit of area and the chosen unit of area is a square whose side is a unit of length and if the unit of length be a metre, the unit of area will be called a square metre and similarly if the unit of length be a centimetre, the unit of area will be a square centimetre.

Then why are we using these symbols like m^2 or (cm)^2 to represent the unit of area when they have nothing to do with the whole procedure of measuring the areas? What’s the reason behind such a representation?

NOTE – Sir I have asked many people the same thing and some of them gave me REASON 1 while others gave me REASON 2 but none of the reasons sounded to me accurate and I’ve explained why is it so.

REASON 1:
They said, “Area is measured by multiplying the length and the breadth, since both are measured in terms of the unit of length therefore by multiplying the units too we end up with m^2 as the units of the area.”

WHY NOT ACCURATE:
This can’t be a reason behind such a representation, since area is not what we get by multiplying the length and the breadth (this is rather an analogue or to be more precise it’s something that we infer from the actual procedure of measuring the areas and that too is wrongly said as it’s not the product of length and breadth, it’s rather the product of their numerical values ONLY).

REASON 2:
They said, “m^2 is just a shorthand or an easy way to write square metre.”

WHY NOT ACCURATE:
Now this reason has two problems. Firstly, if it’s really just a shorthand then why do we chose SO SPECIFIC one and not choosing sq.m as a shorthand (which sounds more logical and is more shorthand-oriented)?
Secondly, in the context of areas, both square metre and m^2 represent totally different mathematical ideas (though they sound somewhat similar while pronouncing). Square metre represents the defined unit of area i.e. a square with side length equal to 1 metre WHEREAS m^2 represents an arithmetical operation wherein length of 1 metre has been multiplied with another 1 metre length (which has nothing to do with calculation of areas).

Sir PLEASE explain then what’s the reason behind such a representation?

I WILL BE HIGHLY GRATEFUL TO YOU FOR THE EXPLANATION AND POINTING ME TO BE INCORRECT, IF ANYWHERE.

Myself – Paras Mahajan from INDIA.

31. Colton Flowers

Hello Professor,
I am a student studying linguistics and mathematics at the University of Arizona. I am actually in a class taught by Noam Chomsky, and I wanted to get your take on the idea that language is an instance of “the infinite use by finite means”. I am not sure if you are familiar with the concept, but this is what was taught:
1) The human brain is finite.
2) Since language is recursive, one can always construct a larger sentence from an existing one, so the set of possible sentences is infinite.
3) Because language is infinite and the brain is finite, the brain must have some generative system in place to generate one of the infinite many sentences there are instead of storing each one.

I take issue with the second point, and I wanted to hear your thoughts on the matter. What do your qualms with infinity say about an infinite corpus of sentences? Does this line of reasoning hold even if one believes infinite sets to be possible?

Thank you,

Colton

32. Sanjoy Nath

Dear Respected Sir,
I was searching for some automated force flow dynamics due to any loading on Steel Structures or RCC Structures components where large numbers of Fourier Series and Trigonometric Expressions present.
To Render ALL POSSIBLE CONFIGURATIONS of vector flow i have designed Sanjoy Nath’s Geometrifying Trigonometry(C) and its algorithms . I need some practical unsolved problems and your insights to proceed with these way of Rendering and Analyzing Geometries ALL POSSIBLE hidden inside Trigonometric Expressions
Thanks And Regards
Sanjoy Nath
Founder of Sanjoy Nath’s Geometrifying Trigonometry(C)

33. Aravindh Vasu

Hello sir, just saw your gorgeous video on wild linear algebra ( Taylor series as a Change if basis ). I’ve no words, that was just beautiful. I’ve an obligation; can you write a blog or a video, considering Laplace transform as a change of basis? Cause I think Laplace transform is a change of basis to eigen basis considering differential equations, Ami right ?

34. Alok Krishen

Dr. Wildberger, I wonder if you could help me understand the concept of “area”. For a rectangle it requires “ length” and “breadth”. How did the Greeks arrive at area=length x breadth when they thought in terms of “quadrances” instead of “lengths”. Did they or anyone define area?

1. njwildberger: tangential thoughts Post author

Hi Alok, The concept of area is actually an affine concept, and so is prior to Euclidean geometry. It really only depends on having parallels and translation, not requiring notions either of length or quadrance. Not sure that the ancient Greeks thought that way though. The distinctions between affine, projective and Euclidean geometry is a more later development, probably only really becoming clear in the 19th century.

Hi professor Wildberger, thank you for your inspirational videos.

I’m looking for books that give an in depth explanation of mathematics together with its history. Which books should I study that explain mathematics from its very beginning and give proofs of its laws?

36. Bertrand

I’ve publishe my draft v2 « is infinity a number?  » age 55 this summer as a serious hobby. In September I’ve spent a significant amount of my hobby time, improving my draft v3 introducing sequences, and then this week I have discovered you were talking also about onsequences. From now on it seems I’ve 2 compatible sources for my my work: you and myself Unfortunately it may delay my work as I’m now curious to learn more from your video. The only difference so far with my work is that I’m considering onsequences as
indefinitely large finite sequences and I have very specific views about a clear cut between indefinitely large finite numbers bounded by infinite actual infinite numbers which do not exist. But I can feel if not aligned, my views are extremely close to your !
I will contact you when my draft v3 « is infinity a number?  » is published

1. Meïr Krukowsky

Dear Professor Wildberger,
Don’t you think П has no finit value because it is the parameter we use to calculate the length of a circumference,which is an arc with the side of polynomials which is a straight line.There is nothing more to it.Nothing mysterious and methaphysical like you show with your model with galaxys.
Real numbers do not exist.
I think mathematiciens agree with that.
Mathematics deal with real numbers as with limits.Real numbers are just limits
We can add,we can multiplie and so further.
Best regards
Meïr Krukowsky

37. Scott A Miller

Dear Professor,
This is to thank you for helping me to visualize quaternions,
which not even the book, “Visualizing Quaternions” could do.
Since then, I have found your Rational Trigonometry to be
astonishingly informative. Currently, I am seeking to incorporate
Rational Trigonometric principles into Geometric Algebra,
both for proofs and for extending geometrical comprehension.
In my opinion, you are a genius. Thank you, sir.
– s.a.m., Chico, California
December 19, 2020

1. Anonymous

Superb, thank you. Clearly RT + chromogeometry
addresses what I seek in (what I suppose is) Relational Logic
at the necessary fundamental algebraic level. I hope that your student,
on these topics. I have been a database programmer who is now trying
to take part in the revolution toward synthetic geometry.
Your dihedron exposition is positively unifying, alarmingly so to me!
Brilliant and exciting, with prof. NLW at NSW leading the way.
with enormous gratitude, -sam.

38. Scott A Miller

Dear Professor, Congratulations upon your announced retirement!
Your student G.A. Notowidigdo has kindly responded to me.
I have now watched your videos on Dihedron algebra many times,
since you yourself kindly responded to direct me to those.
Your work has utterly changed my life, ever since you were
the only person ever to get me to visualize Quaternions. Now this.
through my Russian connections, but I owe you for that book.
And much more. Best wishes to you and your family,
I believe you are the greatest geometer of modern times.
I too am nearing retirement, but I intend to prove your work.
Scott Alan Miller,
Chico, CA, USA

39. Sagnik Chatterjee

Hello , this blog and the youtube channel are truly great. As a high school student myself and self-learning mathematics ,I truly find the information you put out there and the way you present the problem very engaging.
Thank you again for your videos and the blog.

1. njwildberger: tangential thoughts Post author

Thanks Sagnik, I hope you keep on watching the videos. Also please consider joining the Wild Egg Maths YouTube channel, where I am currently going through a novel approach to solving polynomial equations that will be quite of interest even to high school students.

40. Othmar Stehlik

Hi Prof. Wildberger,

Great blog and channel. I graduated in math with a master, focused on infinite dimensional Lie algebras and a new approach to Weyl’s character formula for loop groups. however messed up my PhD as the broadness of topics coming together in this area always carried me away and I lost focus.
Now nearly 20 years later, I am taking up graduate level books again simply for fun and with my personal goal to get up to speed in algebraic geometry in particular Langland’s conjecture and its connection to Lie theory.
Keep up the great work. Mathematics is one of the few great sciences that in theory are accesible to anyone with pen and paper.

41. Drake Sterling

NJW, This is to thank you for being for me the teacher I never had in school. Worth the wait!
You were very kind to direct me to your series on Dihedral Algebra. Not a mathematican, I neither blog nor post anywhere (typically). All I am is a career relational logician (database engineer), and programmer. But I took up Astronomy late in life, and so had to have Mathematics, at which I am actually retarded; or, as the Stanford boffs would say, my intelligence is mostly verbal, but definitely not mathematical. Geometry is my only rational strategy. Today, after a decade of intensive study, I program in 5D CGA, which I believe (know) to be the greatest discovery in Language of all time. When I finally reached discovery threshold (in mathematical Physics), I was stumped by spaceTime, because Time is not spatial, yet it works. In seeking to break this evil bind, I wrote to you about my research into rotations, and you pointed me instantly to Dihedral algebra. That’s when I realized how all this ties into 5D CGA. See my videos (not online yet). The relativistic dihedral basis unlocked the subject at the correct rational level, so that now I have just completed a 100-hour video series on how to treat Time in 4D. I am making extremely good discoveries regularly now,and am about to get the Hubble Constant from phyiscal constants. You are my hero, and I know what I am talking about. Thank you, again, you are one of The Rare Great Geometers. Thank you, professor! -Drake Sterling
A&E Anagalactic and Extragalactic Interactive Online University
To Infinity – and beyond!

ÆЮ – Ana- and Extra-galactic Interactive Online University
P.S. – your command of Geogebra is positively superb

42. Dr. Gene Sprechini

Dr. Wildberger,
I am a member of the Mathematical Sciences department at Lycoming College in Williamsport, Pennsylvania (USA). I coordinate the actuarial science major and all the statistics courses, but I recently found myself assigned to teach undergraduate Real Analysis, because of a staffing issue. I am a statistician, and after not having been involved heavily in pure mathematics for over 30 years, I wanted to do a good job teaching the course. However, after some investigation into what I should be teaching, and some attempts to design a really great course, all I encountered was (1) inconsistent rigor, (2) problematic definitions, (3) impoverished examples, and (4) reliance on nonintuitive axioms. Sound familiar? Because I am practically quoting you. In fact, as soon as I ran across your videos and website, I came to the realization that the reason I was not feeling good about teaching the course was NOT because I was away from it way too long. BOTTOM LINE: Where can I access source materials to teach undergraduate Real Analysis this coming spring semester, which would be based on your rigorous development of pure mathematics? Dare I ask if such materials even exist?
Dr. Gene Sprechini