John Baez
John Baez, a mathematical physicist, writes on math, physics, category theory and complex systems on his Azimuth blog.
What HN says
HN commenters praise him as a favorite math writer, noting his blog, his long-running This Week's Finds, and his knowledge of music and math.
Stats for nerds
157HN people shared it
294linked in comments
7.2Kstory points
Nov 2025last shared
Top posts on HN
- 1421 person · 528 points · first shared 2013 · 58 comments on HN
- 2Applied Category Theory2 people · 383 points · first shared 2018 · 40 comments on HN
- 3What Is Entropy?2 people · 351 points · first shared 2024 · 200 comments on HN
- 4The Color of Infinite Temperature3 people · 335 points · first shared 2022 · 132 comments on HN
- 5Planets in the Fourth Dimension3 people · 256 points · first shared 2015 · 53 comments on HN
- 6How I Learned to Love Algebraic Geometry2 people · 247 points · first shared 2019 · 54 comments on HN
- 7Dead Stars Don’t Radiate1 person · 246 points · first shared 2025 · 148 comments on HN
- 8Ice3 people · 232 points · first shared 2012 · 12 comments on HN
- 9Mathematical Patterns That Eventually Fail8 people · 224 points · first shared 2018 · 36 comments on HN
- 10Tritone Substitutions1 person · 220 points · first shared 2024 · 134 comments on HN
What HN people wrote when they linked it
- nextaccounticJan 2022
I love John Baez's blog too! But actually I think his long winded, mathematically challenging posts are more interesting. Like this series
https://johncarlosbaez.wordpress.com/2012/01/19/classical-mechanics-versus-thermodynamics-part-1/
https://johncarlosbaez.wordpress.com/2012/01/23/classical-mechanics-versus-thermodynamics-part-2/
https://johncarlosbaez.wordpress.com/2021/09/23/classical-mechanics-versus-thermodynamics-part-3/
https://johncarlosbaez.wordpress.com/2021/09/26/classical-mechanics-versus-thermodynamics-part-4/
An excerpt from the first article:
> The big picture
> Now let’s step back and think about what’s going on.
> Lately I’ve been trying to unify a bunch of ‘extremal principles’, including:
> 1) the principle of least action
> 2) the principle of least energy
> 3) the principle of maximum entropy
> 4) the principle of maximum simplicity, or Occam’s razor
> In my post on quantropy I explained how the first three principles fit into a single framework if we treat Planck’s constant as an imaginary temperature. The guiding principle of this framework is
> maximize entropy
> subject to the constraints imposed by what you believe
> And that’s nice, because E. T. Jaynes has made a powerful case for this principle.
> However, when the temperature is imaginary, entropy is so different that it may deserves a new name: say, ‘quantropy’. In particular, it’s complex-valued, so instead of maximizing it we have to look for stationary points: places where…
- dredmorbiusNov 2020
Both axes are irrelevant (not that the statistics have any validity: itsajokeson.jpg)
The real question is: what tools are people who write truly excellent blogs using?
Rakhim himself is using Hugo.
Gwern organises their blog on a long-content basis using online services but a custom software and design mix, static site.
https://www.gwern.net/About#long-site
John Baez's Azimuth blog runs on Wordpress. https://johncarlosbaez.wordpress.com The wiki is on Instiki: https://www.azimuthproject.org/azimuth/show/HomePage
Steve Keen posts to Patreon: https://www.patreon.com/ProfSteveKeen
Tim Bray's "Ongoing" is "Generated from XML source code using Perl, Expat, Emacs, Mysql, Ruby, Java, and ImageMagick. Industrial-strength technology, baby." https://www.tbray.org/ongoing/
Joey Hess blogs on ikiwiki (wwhich he wrote himself). https://joeyh.name/blog/ https://joeyh.name/code/ikiwiki/
EFF runs Drupal 7 https://www.eff.org/document/end-trust-0
Most Interesting People post to some Wordpress, organisational, social media, or other blogging tool. It's what's easy or available.
My own experience across 20+ years of online posting is a mix of trying to suit my needs and find a good conversation. Currently, HN is one of my principle outlets: the crowd's pretty good, tends to call my bullshit, dang keeps the noise floor down, and Algolia search lets me find my shit. It's not a blog, but it fills some needs and interests.
The problem with "choose the easy path" is…
- SniffnoyAug 2018
> Sure, oridnals are interesting, but in the context of explaining infinity to kids transfinite induction is probably not the easiest thing to throw into the fun basket. Even first-year undergrads often have to learn regular induction!
Sure, but do you really have to explain that?
When I imagine introducing kids to ordinals, like the OP talks about, I'm assuming it's basically taking the approach in, say, John Baez's blog posts on large countable ordinals[1].
[1] https://johncarlosbaez.wordpress.com/2016/06/29/large-countable-ordinals-part-1/ https://johncarlosbaez.wordpress.com/2016/07/04/large-countable-ordinals-part-2/ https://johncarlosbaez.wordpress.com/2016/07/07/large-countable-ordinals-part-3/
> Any examples that you could introduce to a kid who just asked you "What is infinity?" - genuinely curious.
Hm, maybe not. Maybe some of the classic examples of weird things that can happen with transfinite-time processes... but explaining any of that might be hard. And also that might not really be the right time to introduce people to discontinuity.
Really like I said I was basically thinking of the approach above, without application. I think it stands on its own pretty well, it's fun, you can play around with it -- it's basically the "is too, times infinity+1!" game except formalized (so it kind of comes naturally out of something kids already try to do) -- and the questions have actual answers.
- CarolineWAug 2017
That's not the question you asked. If you want to know more about the context of this specific paper then you need to (a) wait for the people in the area to start writing explanations, or (b) ask more specific questions about specific terms.
A good place to start to get a sense of what's going on with this specific paper is this thread, but more particularly, the articles linked from it. One that I think is a great starting point is this one:
https://johncarlosbaez.wordpress.com/2017/08/15/norbert-blum-on-p-versus-np/
But you should perhaps start by asking the question you actually want the answer to - it sounds like you didn't. So take a moment, do some reading, then come back with particular questions. They may already be answered, but before you did the outside reading you didn't realise. That's what happens to me.
- carrolldunhamAug 2019
This paper is so popular all over the web but nobody has ever managed to follow the proof of its 'theorem'. This guy is a math professor and quantum physicist and he was unable to extract any sense from it:
https://johncarlosbaez.wordpress.com/2016/01/27/the-good-regulator-theorem/
He points out that the proof uses terms that aren't even defined. The fact that the authors of the paper are a psychiatrist and, I think a humanities academic, doesn't fill me with confidence that the 'theorem' and its 'proof' are actually those things. It's disquieting to see so many people taking the paper's claim and running with it because it 'resonates'. I know there is also an 'internal model principle' paper which is technically correct but that applies to a specific set of linear systems under specific conditions. - yantramsDec 2018
If I had to choose just one blog or a twitter account for that hypothetical deserted island question(what is the one x-item you'd choose if stranded on a deserted island?), it would be that of John Baez without a second thought. His personal blog and tweets are absolute treasure troves for anyone interested in Math.
https://johncarlosbaez.wordpress.com
https://twitter.com/johncarlosbaezThe recent breakthrough in finding the smallest Lebesgue cover [1] was triggered by one of his blog posts about it a few years back.
1 -- https://www.quantamagazine.org/amateur-mathematician-finds-smallest-universal-cover-20181115/