Simon has been fascinated by these possible-impossible puzzles (that he picked up from the MajorPrep channel) for a couple of days. He prepared many paper visuals so that Dad and I could try solving them. This morning he produced this beautiful piece of design:
This is Simon explaining Diffe-Hellman key exchange (also called DiffeHellman protocol). He first explained the algorithm mixing watercolours (a color representing a key/ number) and then mathematically. The algorithm allows two parties (marked “you” and “your friend” in Simon’s diagram) with no prior knowledge of each other to establish a shared secret key over an insecure channel (a public area or an “eavesdropper”). This key can then be used to encrypt subsequent communications using a symmetric keycipher. Simon calls it “a neat algorithm”). Later the same night, he also gave me a lecture on a similar but more complicated algorithm called the RSA. Simon first learned about this on Computerphile and then also saw a video about the topic on MajorPrep. And here is another MajorPrep video on modular arithmetic.
Take any real number and call it x. Then plug it into the equation f(x) = 1 + 1/x and keep doing it many times in a row, plugging the result back into the equation.
At some point you will see that you arrive at a value that will become stable and not change anymore. And that value will be… φ, the golden ratio!
But this equation also has another answer, -1/φ. If you plug that value into the equation, it will be the same, too. The real magic happens once you have rounded the -1/φ down (or up), i.e. once what you plug into the equation is no longer exactly -1/φ. What happens is that, if you keep going, you will eventually reach… φ as your answer!
Simon saw this interesting fact in a video by 3Blue1Brown and then came up with a proof as to why it happens.
Simon also sketched his proof in GeoGebra: https://www.geogebra.org/classic/zxmqdspb
While in Southern France, Simon really enjoyed solving this puzzle (he originally saw in a Brilliant.org vid). He was so happy with his solution he kept drawing it out on paper and in digital apps, and later shared the puzzle on Twitter. This sparked quite a few reactions from fellow math lovers, encouraged Brilliant to tweet new puzzles and now Brilliant follows Simon on Twitter, how cool is that!
What do I love most about Simon’s learning style and being around him are the precious moments he pulls me out of my regular existence, sits me down next to him and shares a piece of his sharp vision with me. I often take notes to make sure I haven’t missed out on the details. Reading back the notes I am often surprised at the hidden layers in his razor-sharp logic that hadn’t revealed themselves to me at first or had even seemed irrelevant to my journalist mind eager to cramp everything to the size of a cocktail bite. Sometimes, Simon takes over and types the rest of the blog entry himself. Like this time.
Dad says he saw someone by the swimming pool reading the book A Mathematician’s Apology. We google it and find out it’s a 1940 essay by British mathematician G. H. Hardy about the beauty of pure mathematics. Knowing how much Simon is drawn towards pure mathematics and that he, too, prefers pure mathematics to applied mathematics, I tell him about our discovery. Simon replies that it’s a silly question to ask him whether he knows Hardy: Yes, Hardy was actually the one who invited Ramanujan!
Simon pauses his breadboard tutorial, comes to the balcony with the view across the Cote D’Azur, sits down against the wall of bright purple flowers and patiently tells me an interesting fact about Hardy. It’s just a fleeting tiny conversation, but the beauty of Simon’s precise memory, the connection I feel to Simon and the setting is so striking I would rather grab my video camera but I don’t dare move as not to lose momentum. I later ask Simon to repeat the facts he told me so spontaneously.
“Hardy came up with the total number of chess games. Well, Shannon estimated it to be 10^120, however Hardy estimated it to be 10^…, 10^50.
Clarification: the former is:
1 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
(1 with 120 zeros)
And the latter is:
1 with 100 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 zeros
(1 with, a 1 with 50 zeros, zeros)
Simon was showing Dad a graph of how technology is developing exponentially, y = a^x. Dad asked for a specific value of a, and Simon said: “All exponentials are stretched out or squished versions of the same thing.” He then quickly came up with the proof (“a few lines of relatively simple algebra”). “If all exponentials are pretty much the same, that means that all exponentials have proportionately the same derivative.”
Simon has written a code in Python that generates primes using the finite list from Euclid’s proof that there are infinitely many primes. “Starting with one prime (2) the code uses the finite list to generate a couple more numbers that aren’t in the list but are primes. It may not even get to all the primes in the long run!” There is only one problem with Simon’s algorithm…
Simon has written down Euclid’s proof in his own words first https://imgur.com/ML2tI6n
and then decided to program it in Python.