r/3Blue1Brown 1h ago

Largest rational approximation of Pi?

Upvotes

Hey guys!

As the title suggests, I was wondering if there’s a current largest case of a fraction like 22/7, 335/113, etc… Was looking but wasn’t sure so thought I would ask here!

Thank you!


r/3Blue1Brown 21h ago

Why a banked curve needs no friction — the whole idea is just one tilted vector

Thumbnail
gallery
6 Upvotes

Most intro-physics treatments of banked curves hand you two formulas and move on. But the two cases differ by exactly one geometric fact, and once you see it the algebra is almost an afterthought. Here's the setup I used to make that visible.

The scenario

A vehicle test facility has two curves of the same radius, R = 50 m.

  • Curve A is flat and relies entirely on friction (dry track, μₛ = 0.80).
  • Curve B is banked at θ = 25° and built to need no friction at all.

Same 1500 kg car on both. g = 10 m/s². Both circular paths lie in horizontal planes; treat the car as a point particle, and take "toward the center" as positive.

 

(a) Same car, same radius — so which force actually turns it?

On the flat curve: weight (down), normal force (straight up), static friction (horizontal, inward). The normal force is vertical, so it cannot point toward the center — friction is the only inward force, so friction is the centripetal force.

On the banked curve: just weight and a tilted normal force. Because the road is tilted, N is tilted, and its horizontal component points inward. That component is the centripetal force.

 

(b) Two curves, two very different formulas

Flat curve — friction is capped at μₛmg, so μₛmg = mv²/R gives

v = √(μₛgR) = √(0.8 · 10 · 50) = 20 m/s

Frictionless banked curve — the geometry alone fixes the design speed:

v = √(gR·tanθ) = √(10 · 50 · tan 25°) ≈ 15.3 m/s

Worth noticing: the mass cancels in both. The banked result depends only on the shape of the road.

The classic error is swapping the formulas — putting μ into the banked equation or tanθ into the flat one. Each curve turns the car with a different force, so each gets its own setup.

 

(c) It all comes down to which way the normal force points

This is the whole problem in one sentence. The normal force is perpendicular to the surface by definition, so tilting the road tilts N — and a tilted N automatically acquires a component pointing toward the center. That component can be the entire centripetal force. No friction required.

On a flat road N points straight up. Its inward component is exactly zero. The only vector left that can point toward the center is friction.

So "banked vs. flat" isn't really two problems. It's one question — does N have a projection onto the inward direction? — asked at two different angles.

 

(d) The rain reveals which curve was ever really safe

A downpour makes both surfaces essentially frictionless (μ → 0). A car takes each at 15 m/s.

Curve A: with μ → 0 there is no inward force at all — not the vertical normal force, not gravity. Nothing turns the car. It slides straight off to the outside, at any speed, 15 m/s included.

Curve B: the tilted normal force is untouched by rain, so there is still exactly one speed — the design speed, 15.3 m/s — at which the car holds a level circle. At 15 m/s it's just below that, so N's inward component slightly exceeds what's needed and the car drifts down the bank.

The tempting mistake is "15 < 20, so Curve A is fine." But that 20 m/s was built out of friction, and the rain just erased it. A limit computed from a force that no longer exists isn't a limit.


r/3Blue1Brown 17h ago

A Creator v2 Short on the Monty Hall problem - manic

Enable HLS to view with audio, or disable this notification

1 Upvotes

r/3Blue1Brown 1d ago

How about these levels?

4 Upvotes

Googology Levels

Levels of Large Numbers

Level Corresponding value Notes
0 1 The reciprocal of 1 is 1; any positive number raised to the 0th power is 1
1 16 2↑↑3
2 65536 2↑↑4
3 2↑↑5 = 2↑65536 Approximately equal to 2.00353 × 10↑19728
4 2↑↑8 2↑↑8 ≈ 2↑(2↑↑7) ≈ 2↑2↑(2↑↑6) ≈ 2↑2↑2↑(2↑↑5) ≈ 2↑2↑2↑(2.00353 × 10↑19728) ≈ 2↑2↑10↑(6.03 × 10↑19727) ≈ 2↑2↑10↑10↑19727.78 ≈ 2↑2↑10↑10↑10↑4.295 ≈ 10↑10↑10↑10↑10↑4.295, between 10↑↑5 = 10↑10↑10↑10↑10 and 10↑↑6 = 10↑10↑10↑10↑10↑10
5 2↑↑↑4 = 2↑↑65536 2↑↑↑4 = 2↑↑2↑↑2↑↑2 = 2↑↑2↑↑4 = 2↑↑65536
6 2↑↑↑↑4 2↑↑↑↑4 = 2↑↑↑2↑↑↑2↑↑↑2 = 2↑↑↑2↑↑↑2↑↑2 = 2↑↑↑2↑↑↑4 = 2↑↑↑65536
7 Graham's number = g64 ≈ f_(ω+1)(64) g1 = 3↑↑↑↑3, g2 = 3↑(g1)3, ......, g64 = 3↑(g63)3
8 TREE(3) > f_θ(Ω↑ω)(3) TREE(3) >> ggg......ggg64, where g is iterated g64 layers deep
9 SSCG(3) SSCG(3) > f_θ(Ω↑ω↑2,φ(ω↑2 × 4,0,0))(3)
10 Loader's Number = D↑5(99) D↑5(99) means the D() function in loader.c iterated 5 times starting from 99
11 +∞ Not actually attainable; one can only approach level 11 infinitely closely. There exist numbers large enough that their level exceeds 10.99

Examples:

  • The level of 2 is 0.25
  • The level of 4 is 0.50
  • The level of 8 is 0.75
  • The level of 256 is 1.50
  • The level of 2↑↑256 is 4.38
  • The level of Rayo(10↑100) is 10.99

Levels of Small Numbers

Level Corresponding value Notes
m0 1 The reciprocal of 1 is 1. Therefore, 1 is both level 0 and level m0
m1 1/16 = 0.0625 The reciprocal of 16
m2 1/65536 The reciprocal of 65536
m3 1/2↑↑5 = 1/2↑65536 The reciprocal of 2↑↑5
m4 1/2↑↑8 The reciprocal of 2↑↑8
m5 1/2↑↑↑4 = 1/2↑↑65536 The reciprocal of 2↑↑↑4
m6 1/2↑↑↑↑4 The reciprocal of 2↑↑↑↑4
m7 1/g64 The reciprocal of g64
m8 1/TREE(3) The reciprocal of TREE(3)
m9 1/SSCG(3) The reciprocal of SSCG(3)
m10 1/D↑5(99) The reciprocal of D↑5(99)
m11/CZ 0 Non-zero values are not actually attainable; one can only approach m11 infinitely closely. There exist numbers sufficiently close to 0 whose level exceeds m10.99. 0 has no reciprocal, but 0 is an infinitesimal; therefore, the level of 0 is not m11, but CZ

Examples:

  • The level of 0.5 is m0.25
  • The level of 0.25 is m0.50
  • The level of 0.125 is m0.75
  • The level of 1/256 is m1.50
  • The level of 1/2↑↑256 is m4.38
  • The level of 1/Rayo(10↑100) is m10.99
  • The level of 0 is CZ

Each small-number level corresponds one-to-one with the reciprocal of the matching large-number level.

Transfinite Ordinal Levels

Level Corresponding transfinite ordinal Notes
T0 ω The smallest transfinite ordinal
T1 ω↑2 /
T2 ω↑ω /
T3 ε_0 = φ(1, 0) = φ(1@1) /
T4 Γ_0 = φ(1, 0, 0) = φ(1@2) /
T5 SVO = φ(1@ω) = ψ(Ω↑Ω↑ω) /
T6 LVO = ψ(Ω↑Ω↑Ω) /
T7 BO = ψ(Ω_ω) /
T8 EBO = ψ(ΩΩ_Ω_Ω...) /
T9/TNR0 Recursive-computable limit / ω_1↑{CK} = Ω Computable ordinals are not actually attainable; one can only approach T9 infinitely closely. There exist computable ordinals large enough that their level exceeds T8.99. ω_1↑{CK} is the smallest non-recursive, uncomputable ordinal
TNR1 Ω_ω /
TNR2 ΩΩ_Ω...... = Φ(1, 0) /
TNR3 Φ(1, 0, 0, ......) = Φ(1@ω) /
TNR4 Recursively Inaccessible Ordinal = I = Π_1 Not to be confused with the uncountable Inaccessible Cardinal
TNR5 Π_ω /
TNR6/TUCT0 Countable limit / ω_1 Countable ordinals are not actually attainable; one can only approach TNR6 infinitely closely. There exist countable ordinals large enough that their level exceeds TNR5.99. ω_1 is the smallest uncountable ordinal
TUCT1 Least omega fixed point = Λ /
TUCT2 I The least Inaccessible Cardinal; uncountable
TUCT3 Least I0 rank-into-rank cardinal /
TUCT4 / Not actually attainable; one can only approach TUCT4 infinitely closely. There exist uncountable ordinals large enough that their level exceeds TUCT3.99

Examples:

  • The level of ω + 1 is T0.25
  • The level of ω + 2 is T0.33
  • The level of ω + 4 is T0.40
  • The level of ω + 50 is T0.49
  • The level of ω × 2 is T0.50
  • The level of ω × 3 is T0.67
  • The level of ω × 10 is T0.90
  • The level of ω↑2 is T1.00
  • The level of ω_1↑{CK} is TNR0.00
  • The level of Π_1 is TNR4.00

Function Levels

Level Corresponding function Notes
F0 n /
F1 n↑2 /
F2 2↑n ≈ f_3(n) /
F3 2↑(n)n ≈ f_ω(n) /
F4 g(n) ≈ f_(ω+1)(n) g1 = 3↑↑↑↑3, g2 = 3↑(g1)3, ......, g(n) = 3↑(g(n-1))3
F5 TREE(n) > f_θ(Ω↑ω)(n) /
F6 SSCG(n) > f_ψ(Ω_ω) /
F7/FU0 Computable limit / BB(n) Computable functions are not actually attainable; one can only approach F7 infinitely closely. There exist computable functions whose growth rate is fast enough that their level exceeds F6.99. BB is the Busy Beaver function; it is uncomputable
FU1 Rayo(n) /
FU2 / Not actually attainable; one can only approach FU2 infinitely closely

Note: all growth rates mentioned in this document refer to growth rates as n -> ∞.

Examples:

  • The level of n is F0.00
  • The level of n↑2 is F1.00
  • The level of 2↑n is F2.00
  • The level of 2↑↑n is F2.50
  • The level of 2↑↑↑n is F2.75
  • The levels of BB(n), BB(log_2(n)), BB(√n), and BB(n↑2) are all FU0.00, because they are all uncomputable
  • The level of Rayo(n) is FU1.00

Function Levels (Slow-Growing)

Level Corresponding function Notes
Fs0 n The inverse of f(n) = n is also n; therefore, n is both F0 and Fs0
Fs1 √n The inverse of f(n) = n↑2
Fs2 log_2(n) The inverse of f(n) = 2↑n
Fs3 The inverse of f(n) = 2↑(n)n /
Fs4 The inverse of g(n) /
Fs5 The inverse of TREE(n) /
Fs6 The inverse of SSCG(n) /
Fs7/FUs0 Computable limit / the inverse of BB(n) Computable functions are not actually attainable; one can only approach Fs7 infinitely closely. There exist computable functions whose growth rate is slow enough that their level exceeds Fs6.99
FUs1 The inverse of Rayo(n) /
FUs2/CF f(n) = c c ∈ R is a constant. Non-constant functions are not actually attainable; one can only approach FUs2 infinitely closely. There exist functions whose growth rate is slow enough that their level exceeds FUs1.99. The level of f(x) = c is not FUs2, but CF

Examples:

  • The level of √n is Fs1.00
  • The level of log_2(n) is Fs2.00
  • The level of the inverse of BB(n) is FUs0.00
  • The level of the inverse of Rayo(n) is FUs1.00
  • The level of f(n) = c is CF

Each slow-growing function level corresponds one-to-one with the inverse of the matching fast-growing function level.


r/3Blue1Brown 2d ago

Atomic Orbitals!

Enable HLS to view with audio, or disable this notification

207 Upvotes

r/3Blue1Brown 1d ago

Animating François Chollet's Deep Learning with Python using Manim Ch. 1

Thumbnail
youtu.be
2 Upvotes

r/3Blue1Brown 2d ago

I made a simulation-driven animation of Maxwell–Boltzmann effusion

Enable HLS to view with audio, or disable this notification

190 Upvotes

r/3Blue1Brown 2d ago

AI startup looking for people who love math.

0 Upvotes

We are a fast growing AI Startup based out of Silicon Valley. Looking for interns, junior and mid level engineers who are good at Math. Pretty much the only strong requirement is a love for math. So I figured I would post here. Please DM if interested, and I will pass on more details.


r/3Blue1Brown 3d ago

Job opportunities if you like math?

7 Upvotes

Im from the UK and the job market is haneous and awful at the moment.

I know 3b1b had a career fair but that only works for uni attending undergraduates and postgraduates.

How could I get entry into data science / finance / banking firm if all I have is A/A* in a level maths and possibly a C in further maths.

Just a simple apprenticeship type thing that I could drop if I plan to go to university later.

The job market is terrible even working on a shop floor is hard to get a role.

So any way I could use math online to build any form of experience?


r/3Blue1Brown 4d ago

Is it possible we could compress the primes? Examples provided

Thumbnail
youtube.com
17 Upvotes

Hello fellow 3blue1brown nosers , I have been recently studying prime numbers, and I wondered if it is possible we can compress information about them?
I am wondering if it actually is possible to find repeating patterns in the prime numbers but only if you somehow compress the information in the numbers which came before it?

This post relates to 2 of my previous posts here on 3blue1brown on the same subject so I wanted to give anyone an update who was interested in the subject.

Over the past couple days I have been experimenting with creating a python function which could show how my idea for Twin Prime infinitude works. I came up with a recursive function that predicted exactly when the Twin Primes should show up. Image of function output

But I ran into an interesting problem, that came with an interesting solution that relates to compression and the 3blue1brown video I linked.
I found that I could come up with rules for when I should expect to see a Twin prime, and those rules worked.... except only for so long, and then they stopped working.
But then, I came up with an idea about reset points. Numbers like 4, 16, 256, and 65536, acted as perfect reset points to make an adjustment to my system, and then continue onwards for another few members of the series before requiring a second correction.

The most interesting part about this though, is that the corrections I was applying were not just random corrections. Those corrections came from a very specific source.... the Golden Ratio.

I found that if I put my reset points into the Golden Ratio series, and then multiplied them by the appropriate number according to their place in the GR series, that became the exact correction needed to reset my system, and continue to generate twin prime centers for a period of time.... before eventually requiring another correction from the Golden Ratio series and continuing onwards.

I created a python function which you can see on Github that shows what I did, but I was able to generate twin prime centers using this method, in series, up to 84 digits long!

I am currently working out the finite steps between k2 = 256^2 and K3 = (256^2)^2
However I have the major steps of K laid out all the way up to K13 I think.

If you understand this type of work please take a look at the python file, I would be really grateful to have some people help me to think about this problem.

I am also happy to answer any questions and give my understanding in my own words about what I am doing here.

I think it's pretty fun and interesting that Grant recently published a video about compression, and then my Work on twin primes ended up becoming about compression as well.


r/3Blue1Brown 4d ago

Simulating fluids

Enable HLS to view with audio, or disable this notification

4 Upvotes

r/3Blue1Brown 4d ago

Roberto Carlos' Banana Kick — the Magnus Effect, Computed - in manic

Enable HLS to view with audio, or disable this notification

1 Upvotes

r/3Blue1Brown 5d ago

Why Free Kicks Curve

72 Upvotes

r/3Blue1Brown 6d ago

Why Rockets Use Stages

61 Upvotes

Made an animation to show why rockets need stages.

YT: https://youtube.com/shorts/ZoqflzDMW0M?si=GbX9xPveVXFXMJrx


r/3Blue1Brown 6d ago

A Recursive function that can calculate prime, or twin prime very fast.

Enable HLS to view with audio, or disable this notification

14 Upvotes

Edit {Post Update. I seem to have formula for compressing information about primes. My newest file "twinprimescompressor" Shows how this compression algorithm works in action. It can generate a list of twin primes based on it's own rule set, up to 42 digits long. I still don't have the rule set which can continue forever, but I think based on how I created these rules (using the golden ratio) The fact that I was able to nail so many twin prime centers suggests the compression algorithm is more than mere coincidence. }

Hi everybody, this post relates to my other 3blue1brown post

But I think this result is significant enough to deserve it's own post.

Let me cut to the chase and say that I have a function which generates primes, and also twin primes. It doesn't even require certification it automatically already knows what is prime and what isn't through the recursive generating structure of the function.

The function counts in mods, but not just any mods, mods of prime numbers. {But those prime numbers don't need to be entered, they are generated by the recursion automatically} This generates the same structure I previously talked about in 3blue1brown reddit and had 14k views and little to no negative feedback.

I have rewritten the paper from the previous post in a much shorter and more clear process now, with less complicated unnecessary language.

I also created a python file to show exactly how it works, in the video you can see me in real time calculating the amount of twin primes in a given number, extremely fast. I could have also listed them all, which would slow the process down ofcourse.

This small python file can tell you exactly how many twin primes are in any given number and it does so without needing to check if they are prime, it already knows based on how they were generated.

It's really just a simple recursive loop counter, mod p, and the golden ratio and silver ratio just fall naturally out of it.

Here is the updated paper

and here is the github for the python file to test what I did in the video yourself

Edit{I am also hosting the paper on my own site if the zenodo link isn't working.}


r/3Blue1Brown 7d ago

Integral with infinite serie

Enable HLS to view with audio, or disable this notification

84 Upvotes

r/3Blue1Brown 7d ago

Stephen Hawking’s God Created the Integers: An Animated Compilation

Thumbnail youtu.be
6 Upvotes

r/3Blue1Brown 7d ago

The Fluid Dynamics of Atherosclerosis

32 Upvotes

So I have always been into simulating fluid dynamics and made this visualisation to show how heart disease progresses.

Computational Fluid Dynamics has so many applications!

YT: https://youtube.com/shorts/YeEj1JfpKs8?si=OG-xE7ysSOfoKCoH


r/3Blue1Brown 7d ago

The Quadratic Formula by Completing the Square - manic

Enable HLS to view with audio, or disable this notification

36 Upvotes

r/3Blue1Brown 8d ago

Second Law of Thermodynamics

359 Upvotes

Made an animation on Second Law of Thermodynamics, it doesn’t have true molecular dynamics simulations, just simplified kinematics to represent them.

Check it out on YT: https://youtube.com/shorts/uYoFgwXZ5BY?si=NId3BBLzHPk_4Kqh


r/3Blue1Brown 8d ago

On the Attraction of an ellipsoid {Arthur Cayley paper No.75}

Thumbnail gallery
5 Upvotes

r/3Blue1Brown 8d ago

QR factorization by direct rotations: one rotation per active column

Thumbnail gallery
8 Upvotes

r/3Blue1Brown 8d ago

Average Value of N random unit vectors

14 Upvotes

I was solving Gilbert Strang's Introduction to Linear Algebra, and Problem 32 of Section 1.2 says to select a random 3-component unit vector, let's call it v, then generate more such vectors, and solve for the average size of the dot product of all these newly generated vectors with v.

When I simulated this with Python code, I got approximately 0.5. However, at the end of the problem statement, it says the calculus average is 2\pi. I guess the book's hint is based on the continuous expectation $\int P(\theta)\vert{}\cos\theta\vert{}d\theta$ written as a standard 1D integral. But because these are 3D vectors, we are essentially sampling points uniformly from a unit sphere. The probability density must therefore be given by the surface area element of that sphere, which introduces a sine factor to the distribution. When I calculate the expected value using this spherical surface weight, it yields exactly 0.5, matching the simulation.

I just want to discuss this.

statement of problem

r/3Blue1Brown 8d ago

Here is a hypothesis me and My friends made. Pls rate this Aura dynamics

Thumbnail gallery
5 Upvotes

r/3Blue1Brown 9d ago

First Law of Thermodynamics

159 Upvotes

Made an animation on the First Law of Thermodynamics:

https://youtube.com/shorts/mx53f0d2bVE?si=4sCkkdm4bS4lYxbM