Uploaded January 2025 | Updated September 2026, 2 weeks ago
This is a corrected version of a video that I uploaded two days ago. After a critical mistake was discovered in the "Nature's Numbers" part of the video, I decided to scrap the original video, fix the errors and republish the video (many more hours down the drain :( Anyway, had to be done. Just in case you are wondering my list of best approximations of pi did not fit in with my definition. This was first pointed out by @typha
I've collected the comments on the original video in this pdf file
qedcat.com/phyl/comments_collection.pdf
If you've got access to Mathematica, you can download my Helicone lab here: qedcat.com/phyl/helicone.nb
0:00 Intro
2:48 Helicone lab!
9:41 Fibonacci Christmas tree
12:28 Number scope
17:22 Nuts and bolts
23:41 Fractional angles
27:34 3, 22/7, ...
34:07 Nature’s numbers
41:45 Best Fibonacci fractions
43:36 Original Helicone Puzzle
45:55 Microscope zooming spectacle
47:05 Thanks!!
John Edmarks website with sections dedicated to his helicone and presentations by him about his work:
johnedmark.com
johnedmark.com/#/rotating
johnedmark.com/talks
If you want to buy one of these helicones google both "helicone" and "lollipopter".
Christian Merighi's online app (needs WebGPU). Quite wonderful, really. On my mac it works best in using the Edge browser.
https://js.pacem.it/3d/helicone
The earlier Mathologer videos about the golden ratio and the Fibonacci numbers in nature referred to in this video:
The fabulous Fibonacci flower formula youtu.be/_GkxCIW46to
Infinite fractions and the most irrational number youtu.be/CaasbfdJdJg
Here is a bare bones version of the microscope: demonstrations.wolfram.com/PhyllotaxisExplained
The technical term for Wolfram's spikey is Rhombic Hexecontahedron.
There is also a plant called Heliconia. However it looks nothing like the Helicone :)
Idea for the real-life Fibonacci Christmas tree: individually addressable LEDs. See, for example, this intro youtube.com/watch?v=LOimwthcdqo&feature=youtu.be
The Moravian star has its own Wiki page. Worth checking out. en.wikipedia.org/wiki/Moravian_star
Mathologer junior is my son Karl and the Mathologer "junioress" behind the camera is my daughter Lara. Thanks Lara and Karl! And in this video we are paying a visit to my office at Monash University in Melbourne, Australia.
In Chinese mathematics, the fractions 22/7 and 355/113 are known as yuēlǜ (约率; 'approximate ratio') and mìlǜ (密率; 'close ratio').
22/7 was found by Archimedes in the second century as part of the strict inequality 223/71 less than pi less than 22/7 and 377/120 was mentioned by Ptolemy in the 3rd century. Also, note that both 223/71 and 377/120 are detected by our number microscope (but not by the usual continued fraction approach).
Relevant encyclopedia of integer sequences entries:
oeis.org/A063673
Music: Christmas tree by Zac Nelson, Tea time by Ty Simon and I promise by Ian Post,
T-shirt: Pretty sure it's this one etsy.com/listing/720022200/pi-christmas-math-science-algebra-gift
Enjoy!
Burkard
This is a corrected version of a video that I uploaded two days ago. After a critical mistake was discovered in the "Nature's Numbers" part of the video, I decided to scrap the original video, fix the errors and republish the video (many more hours down the drain :( Anyway, had to be done. Just in case you are wondering my list of best approximations of pi did not fit in with my definition. This was first pointed out by @typha
I've collected the comments on the original video in this pdf file
qedcat.com/phyl/comments_collection.pdf
If you've got access to Mathematica, you can download my Helicone lab here: qedcat.com/phyl/helicone.nb
0:00 Intro
2:48 Helicone lab!
9:41 Fibonacci Christmas tree
12:28 Number scope
17:22 Nuts and bolts
23:41 Fractional angles
27:34 3, 22/7, ...
34:07 Nature’s numbers
41:45 Best Fibonacci fractions
43:36 Original Helicone Puzzle
45:55 Microscope zooming spectacle
47:05 Thanks!!
John Edmarks website with sections dedicated to his helicone and presentations by him about his work:
johnedmark.com
johnedmark.com/#/rotating
johnedmark.com/talks
If you want to buy one of these helicones google both "helicone" and "lollipopter".
Christian Merighi's online app (needs WebGPU). Quite wonderful, really. On my mac it works best in using the Edge browser.
https://js.pacem.it/3d/helicone
The earlier Mathologer videos about the golden ratio and the Fibonacci numbers in nature referred to in this video:
The fabulous Fibonacci flower formula youtu.be/_GkxCIW46to
Infinite fractions and the most irrational number youtu.be/CaasbfdJdJg
Here is a bare bones version of the microscope: demonstrations.wolfram.com/PhyllotaxisExplained
The technical term for Wolfram's spikey is Rhombic Hexecontahedron.
There is also a plant called Heliconia. However it looks nothing like the Helicone :)
Idea for the real-life Fibonacci Christmas tree: individually addressable LEDs. See, for example, this intro youtube.com/watch?v=LOimwthcdqo&feature=youtu.be
The Moravian star has its own Wiki page. Worth checking out. en.wikipedia.org/wiki/Moravian_star
Mathologer junior is my son Karl and the Mathologer "junioress" behind the camera is my daughter Lara. Thanks Lara and Karl! And in this video we are paying a visit to my office at Monash University in Melbourne, Australia.
In Chinese mathematics, the fractions 22/7 and 355/113 are known as yuēlǜ (约率; 'approximate ratio') and mìlǜ (密率; 'close ratio').
22/7 was found by Archimedes in the second century as part of the strict inequality 223/71 less than pi less than 22/7 and 377/120 was mentioned by Ptolemy in the 3rd century. Also, note that both 223/71 and 377/120 are detected by our number microscope (but not by the usual continued fraction approach).
Relevant encyclopedia of integer sequences entries:
oeis.org/A063673
Music: Christmas tree by Zac Nelson, Tea time by Ty Simon and I promise by Ian Post,
T-shirt: Pretty sure it's this one etsy.com/listing/720022200/pi-christmas-math-science-algebra-gift
Enjoy!
Burkard






![How to build and solve a 4D Rubiks cubes in physical 3D (no simulator!)
I’ve been meaning to make this video about building and solving physical 4D Rubik’s cubes ever since Melinda Green sent me one of her brilliant physical 2x2x2x2s back in 2017! Why did it take so long? Well, this one was especially tricky to get right, and I think it’s probably the video that took me the longest to put together. I really hope you like this one :)
00:00 Intro
03:53 Warm-up
08:59 4d
14:13 Fancy moves
20:24 Solve
26:20 Melinda
31:27 Coding challenge
31:46 Whats next?
33:54 Gallery of animations
36:10 Thank you !
(New) Rensleys simulator of the 2d hedgehog https://renslay.itch.io/2d-hedgehog and my javascript port https://www.qedcat.com/2d_hedgehog/
Ed Collens amazing hedgehog simulator (now with full macro support, avoid Chrome browser, also see my macros for this simulator at the bottom of this blurb)
https://2x2x2x2.vercel.app/cube
Mitchell Mannings similarly amazing but quite different simulator (avoid Chrome browser)
https://rebelkeithy.github.io/TheHedgehog/
Burkards hedgehog simulator (just permutations, avoid Chrome browser)
https://www.qedcat.com/2x2x2x2%20hedgehog
Melindas 2x2x2x2 home page (go there straightaway !)
https://superliminal.com/cube/2x2x2x2/
Melindas YouTube page. Check out her 4D Twisty puzzle playlist.
https://www.youtube.com/c/melindagreen
Zasharan2 Melindas 2x2x2x2 simulator (now also with some macros for twisting corners of the 2x2x2 sides, swapping corners of the 2x2x2 sides, resolving the half-turn parity, and performing a monoflip, just in case you need them/would like to experiment)
https://zasharan2.github.io/2x2x2x2
A playlist of different ways to perform a gyro in Melindas puzzle
https://www.youtube.com/watch?v=d2Fh_1m0UVY&list=PLx1mIVtz33hJbAiFSsfsQ_IlAB1_fuAVc
Joel Karlsson animation showing the correspondence between a different unfolded version of the real 2x2x2x2 and Melindas puzzle. https://www.youtube.com/watch?v=QvhkGRUeGco
Everything about higher-dimensional twisty puzzles
https://hypercubing.xyz
MagicCube4D is a fully functional four-dimensional analog of Rubiks cube plus dozens of other beautiful 4D puzzles.
https://superliminal.com/cube/
Relevant Mathologer videos:
Cracking the 4D Rubiks Cube with simple 3D tricks (solving the 3x3x3x3 in MagicCube4D)
https://www.youtube.com/watch?v=yhPH1369OWc
Can you solve THE Klein Bottle Rubiks cube?
https://youtu.be/DvZnh7-nslo
A simple trick to design your own solutions for Rubiks cubes
https://youtu.be/-NL76uQOpI0
Hyperspeedcube, the name says it all
https://hypercubing.xyz/software/hyperspeedcube/
Piles of other simulators
https://hypercubing.xyz/software/
Grant Staten solves Melindas 2x2x2x2 in under a minute
https://www.youtube.com/watch?v=eIEu38wsjtM
The Unpopular Cuber solves the 3x3x3x3 using a simulator (the crazy action clip at the end of this video are a couple of seconds from this solve)
https://www.youtube.com/watch?v=2GPtYwmSeIU
Some mathematical articles worth checking out:
The Rubik tesseract by H. J. Kamack and T. R. Keane
https://udel.edu/~tomkeane/RubikTesseract.pdf
Rubiks Tesseract by Dan Velleman in Mathematics Magazine (1992), 65:1, 27-36. https://www.jstor.org/stable/2691357
n-dimensional sequential move puzzle https://en.wikipedia.org/wiki/N-dimensional_sequential_move_puzzle
Thank you very much to Melinda for all her help with this video. Also thank you to Vivian and Cristian from Monashs FutureLab for their help with 3d printing the connectors that hold the cubies in my hedgehog together.
Nice insight: Two swaps of the same adjacent cubies in one of the hedgehog sides results in a half-turn of the other side. Try in one of the simulators.
Music: Morning Mandolin by Chris Haugen
Enjoy!
Burkard
P.S.: Here are my macros if you want to use them in Eds hedgehog simulator (save as a .json file and import).
{
groups: [
{
name: Ungrouped,
macros: [
{
name: corner twist,
steps: Ly Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Lz Ix Lz Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ly
},
{
name: corner swap,
steps: Lz Ly Lz Lz Ix Lz Lz Ly Ix Ly Lz Lz Ix Lz Lz Ly Ix Ly Lz Lz Ix Lz Ix Lz Ix Ix Lz Lz Ly Ix Ly Lz Lz Ix Lz Lz Ly Ix Ly Lz Lz Ix Lz Lz Ly Ix Ly Lz Lz Ix Lz Ix Lz Ly Lz
},
{
name: halfturn parity,
steps: Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz
},
{
name: monoflip,
steps: Ly Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Lz Ix Lz Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ly xy Lz yx Ix Ly Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Lz Ix Lz Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Lz Ix Ly Ix xy Lz yx
}
]
}
]
} How to build and solve a 4D Rubiks cubes in physical 3D (no simulator!)](https://i.ytimg.com/vi/d-Yy-ILjM3k/mqdefault.jpg)



