John C. Baez
@johncarlosbaez.bsky.social
Mathematical physicist
Pinned
Thoroughly enjoying this very approachable series from @johncarlosbaez.bsky.social on the Standard Model and quantum mechanics
youtu.be/0yjxqMoX-y8?...
youtu.be/0yjxqMoX-y8?...
Standard Model - Part 1: Particles
YouTube video by John Baez
youtu.be
My series explaining the Standard Model of particle physics has 3 parts so far:
1) Particles
2) The Big Ideas
3) Qubits
Next:
4) Quantum Physics
5) Spinors
Then isospin, pions and more particle physics!
Alas, I've been slowed down by our kitchen remodeling. I want to pick up the pace.
1) Particles
2) The Big Ideas
3) Qubits
Next:
4) Quantum Physics
5) Spinors
Then isospin, pions and more particle physics!
Alas, I've been slowed down by our kitchen remodeling. I want to pick up the pace.
My series explaining the Standard Model of particle physics has 3 parts so far:
1) Particles
2) The Big Ideas
3) Qubits
Next:
4) Quantum Physics
5) Spinors
Then isospin, pions and more particle physics!
Alas, I've been slowed down by our kitchen remodeling. I want to pick up the pace.
1) Particles
2) The Big Ideas
3) Qubits
Next:
4) Quantum Physics
5) Spinors
Then isospin, pions and more particle physics!
Alas, I've been slowed down by our kitchen remodeling. I want to pick up the pace.
Thoroughly enjoying this very approachable series from @johncarlosbaez.bsky.social on the Standard Model and quantum mechanics
youtu.be/0yjxqMoX-y8?...
youtu.be/0yjxqMoX-y8?...
Standard Model - Part 1: Particles
YouTube video by John Baez
youtu.be
November 25, 2025 at 11:02 AM
My series explaining the Standard Model of particle physics has 3 parts so far:
1) Particles
2) The Big Ideas
3) Qubits
Next:
4) Quantum Physics
5) Spinors
Then isospin, pions and more particle physics!
Alas, I've been slowed down by our kitchen remodeling. I want to pick up the pace.
1) Particles
2) The Big Ideas
3) Qubits
Next:
4) Quantum Physics
5) Spinors
Then isospin, pions and more particle physics!
Alas, I've been slowed down by our kitchen remodeling. I want to pick up the pace.
Want to know what climate change will look like?
The drought in Tehran has gotten so bad that people are seriously talking about evacuating this city of 15 million.
"Day zero" is expected in a few weeks. That means NO WATER.
peterfrankopan.substack.com/p/makran-or-...
The drought in Tehran has gotten so bad that people are seriously talking about evacuating this city of 15 million.
"Day zero" is expected in a few weeks. That means NO WATER.
peterfrankopan.substack.com/p/makran-or-...
Makran or Bust: Tehran's water crisis gets worse
Ten days ago I wrote that Tehran was approaching a point where warnings, pressure cuts and appeals to save water would no longer be enough.
peterfrankopan.substack.com
November 25, 2025 at 10:50 AM
Want to know what climate change will look like?
The drought in Tehran has gotten so bad that people are seriously talking about evacuating this city of 15 million.
"Day zero" is expected in a few weeks. That means NO WATER.
peterfrankopan.substack.com/p/makran-or-...
The drought in Tehran has gotten so bad that people are seriously talking about evacuating this city of 15 million.
"Day zero" is expected in a few weeks. That means NO WATER.
peterfrankopan.substack.com/p/makran-or-...
Sometimes gauge transformations have a physical effect.
(The connection to railway tracks is no coincidence: Weyl first introduced the term "gauge invariance", or really "Eichinvarianz", in a theory where lengths could only be compared locally.)
(The connection to railway tracks is no coincidence: Weyl first introduced the term "gauge invariance", or really "Eichinvarianz", in a theory where lengths could only be compared locally.)
#Finland will begin to #Russia - proof its rail network, integrate with EU train infrastructure.
The Finnish government has announced the conversion of its rail network from Russian gauge (1,524 mm) to European standard (1,435 mm).
www.trenvista.net/en/news/flas...
The Finnish government has announced the conversion of its rail network from Russian gauge (1,524 mm) to European standard (1,435 mm).
www.trenvista.net/en/news/flas...
November 24, 2025 at 4:48 PM
Sometimes gauge transformations have a physical effect.
(The connection to railway tracks is no coincidence: Weyl first introduced the term "gauge invariance", or really "Eichinvarianz", in a theory where lengths could only be compared locally.)
(The connection to railway tracks is no coincidence: Weyl first introduced the term "gauge invariance", or really "Eichinvarianz", in a theory where lengths could only be compared locally.)
Tirelessly toiling, I added two of these Clifford algebra isomorphisms to Wikipedia:
Cl(q+2,p) ≅ Cl(p,q) ⊗ Cl(2,0)
Cl(q,p+2) ≅ Cl(p,q) ⊗ Cl(0,2)
Cl(p+1,q+1) ≅ Cl(p,q) ⊗ Cl(1,1)
but without the obscenely large tensor product symbols.
en.wikipedia.org/wiki/Classif...
Cl(q+2,p) ≅ Cl(p,q) ⊗ Cl(2,0)
Cl(q,p+2) ≅ Cl(p,q) ⊗ Cl(0,2)
Cl(p+1,q+1) ≅ Cl(p,q) ⊗ Cl(1,1)
but without the obscenely large tensor product symbols.
en.wikipedia.org/wiki/Classif...
Classification of Clifford algebras - Wikipedia
en.wikipedia.org
November 24, 2025 at 10:48 AM
Tirelessly toiling, I added two of these Clifford algebra isomorphisms to Wikipedia:
Cl(q+2,p) ≅ Cl(p,q) ⊗ Cl(2,0)
Cl(q,p+2) ≅ Cl(p,q) ⊗ Cl(0,2)
Cl(p+1,q+1) ≅ Cl(p,q) ⊗ Cl(1,1)
but without the obscenely large tensor product symbols.
en.wikipedia.org/wiki/Classif...
Cl(q+2,p) ≅ Cl(p,q) ⊗ Cl(2,0)
Cl(q,p+2) ≅ Cl(p,q) ⊗ Cl(0,2)
Cl(p+1,q+1) ≅ Cl(p,q) ⊗ Cl(1,1)
but without the obscenely large tensor product symbols.
en.wikipedia.org/wiki/Classif...
Two new pieces by the teenage Bach just dropped!
They were preserved in only one source.
www.youtube.com/watch?v=0X1x...
(1/2)
They were preserved in only one source.
www.youtube.com/watch?v=0X1x...
(1/2)
NEW BACH PIECE (1 of 2) - Chaconne and Fugue in D minor BWV 1178 (1703) (sheet music)
YouTube video by Im Walde
www.youtube.com
November 23, 2025 at 10:19 AM
Two new pieces by the teenage Bach just dropped!
They were preserved in only one source.
www.youtube.com/watch?v=0X1x...
(1/2)
They were preserved in only one source.
www.youtube.com/watch?v=0X1x...
(1/2)
If you ever want to make an scientist really happy, cite a paper of theirs that nobody paid attention to for decades, and call it "pioneering".
Great new global existence results for classical Yang-Mills theory by Nicolas and Taujanskas:
arxiv.org/abs/2507.16750
Great new global existence results for classical Yang-Mills theory by Nicolas and Taujanskas:
arxiv.org/abs/2507.16750
November 22, 2025 at 9:18 PM
If you ever want to make an scientist really happy, cite a paper of theirs that nobody paid attention to for decades, and call it "pioneering".
Great new global existence results for classical Yang-Mills theory by Nicolas and Taujanskas:
arxiv.org/abs/2507.16750
Great new global existence results for classical Yang-Mills theory by Nicolas and Taujanskas:
arxiv.org/abs/2507.16750
The International Association of Cryptologic Research cancelled the results of its annual leadership election after an official lost an encryption key needed to get access to the results. 😆
www.nytimes.com/2025/11/21/w...
Free here: archive.is/NOnfx
www.nytimes.com/2025/11/21/w...
Free here: archive.is/NOnfx
Cryptographers Held an Election. They Can’t Decrypt the Results.
www.nytimes.com
November 22, 2025 at 5:34 PM
The International Association of Cryptologic Research cancelled the results of its annual leadership election after an official lost an encryption key needed to get access to the results. 😆
www.nytimes.com/2025/11/21/w...
Free here: archive.is/NOnfx
www.nytimes.com/2025/11/21/w...
Free here: archive.is/NOnfx
Had a great conversation with Tymoczko about groupoids in music theory yesterday - I'm the guy introducing him here. But at this Higgs Centre Colloquium, he preferred to talk in terms of things physicists know and love: gauge theory and orbifolds!
media.ed.ac.uk/media/Beyond...
media.ed.ac.uk/media/Beyond...
Beyond the Geometry of Music
Higgs Centre Colloquium - Dmitri Tymoczko
media.ed.ac.uk
November 22, 2025 at 3:14 PM
Had a great conversation with Tymoczko about groupoids in music theory yesterday - I'm the guy introducing him here. But at this Higgs Centre Colloquium, he preferred to talk in terms of things physicists know and love: gauge theory and orbifolds!
media.ed.ac.uk/media/Beyond...
media.ed.ac.uk/media/Beyond...
Coming up in less than 45 minutes: a great talk on groupoids in music theory! You can join us online.
mathstodon.xyz/@johncarlosb...
mathstodon.xyz/@johncarlosb...
John Carlos Baez (@[email protected])
I've been following Dmitri Tymoczko's work on math and music for a while, and lately we've been talking about groupoids in music theory - and now I'll finally get to meet him and talk to him here in E...
mathstodon.xyz
November 21, 2025 at 12:18 PM
Coming up in less than 45 minutes: a great talk on groupoids in music theory! You can join us online.
mathstodon.xyz/@johncarlosb...
mathstodon.xyz/@johncarlosb...
If you wrote the first article in a volume in a Springer Nature journal, congratulations - you won the lottery!
You're getting credit for citations to all the papers in that volume! 🤪
arxiv.org/abs/2511.01675
You're getting credit for citations to all the papers in that volume! 🤪
arxiv.org/abs/2511.01675
November 21, 2025 at 10:07 AM
If you wrote the first article in a volume in a Springer Nature journal, congratulations - you won the lottery!
You're getting credit for citations to all the papers in that volume! 🤪
arxiv.org/abs/2511.01675
You're getting credit for citations to all the papers in that volume! 🤪
arxiv.org/abs/2511.01675
Wow. I knew Lawrence Krauss was a sex pest and a creep. But I didn't know who he ran to for advice when he got caught. Jeffrey Epstein!
All the details are here:
www.youtube.com/watch?v=VNLd...
All the details are here:
www.youtube.com/watch?v=VNLd...
So I'm in the Epstein Files
YouTube video by Rebecca Watson (Skepchick)
www.youtube.com
November 19, 2025 at 9:34 PM
Wow. I knew Lawrence Krauss was a sex pest and a creep. But I didn't know who he ran to for advice when he got caught. Jeffrey Epstein!
All the details are here:
www.youtube.com/watch?v=VNLd...
All the details are here:
www.youtube.com/watch?v=VNLd...
After a huge fire in Oregon, streams were choked with ash — but the water downstream of these beaver dams was crystal clear — and trout were thriving! The dams were acting as a water treatment plant.
www.scientificamerican.com/article/beav...
www.scientificamerican.com/article/beav...
November 16, 2025 at 12:50 PM
After a huge fire in Oregon, streams were choked with ash — but the water downstream of these beaver dams was crystal clear — and trout were thriving! The dams were acting as a water treatment plant.
www.scientificamerican.com/article/beav...
www.scientificamerican.com/article/beav...
A moody evening sky in Edinburgh, viewed from my apartment October 11, 2025.
November 15, 2025 at 10:29 PM
A moody evening sky in Edinburgh, viewed from my apartment October 11, 2025.
Lynx, formerly exterminated in Germany, France and Switzerland, have been brought back to these countries. There's now a campaign to reintroduce them in Scotland! The Greens plan to bring this to a vote.
(1/n)
(1/n)
November 15, 2025 at 1:40 PM
Lynx, formerly exterminated in Germany, France and Switzerland, have been brought back to these countries. There's now a campaign to reintroduce them in Scotland! The Greens plan to bring this to a vote.
(1/n)
(1/n)
All US news media, all the time: men are really in trouble!!! They need more help!!!
40% of young US women: umm, excuse me, can I leave now?
news.gallup.com/poll/697382/...
40% of young US women: umm, excuse me, can I leave now?
news.gallup.com/poll/697382/...
November 14, 2025 at 8:42 AM
All US news media, all the time: men are really in trouble!!! They need more help!!!
40% of young US women: umm, excuse me, can I leave now?
news.gallup.com/poll/697382/...
40% of young US women: umm, excuse me, can I leave now?
news.gallup.com/poll/697382/...
As a happy new resident of Scotland, I just signed a petition to to demand the UK Government tax the super rich to rebuild our NHS, schools, and other public services. Will you sign too?
you.38degrees.org.uk/petitions/ta...
you.38degrees.org.uk/petitions/ta...
Tax the super rich to stop cuts to public services
Across the UK, living standards are falling and millions live in poverty, while the cost of living crisis has made affording the basics difficult. Public services we all rely on - our hospitals, schoo...
you.38degrees.org.uk
November 13, 2025 at 9:41 PM
As a happy new resident of Scotland, I just signed a petition to to demand the UK Government tax the super rich to rebuild our NHS, schools, and other public services. Will you sign too?
you.38degrees.org.uk/petitions/ta...
you.38degrees.org.uk/petitions/ta...
The most beautiful spaces are the irreducible compact Riemannian symmetric spaces! There are the infinite series: the Lie group SO(n), SU(n), Sp(n) and the 6 series listed below.
And then there are the exceptions....
(1/3)
And then there are the exceptions....
(1/3)
November 13, 2025 at 2:55 PM
The most beautiful spaces are the irreducible compact Riemannian symmetric spaces! There are the infinite series: the Lie group SO(n), SU(n), Sp(n) and the 6 series listed below.
And then there are the exceptions....
(1/3)
And then there are the exceptions....
(1/3)
This is the closest you'll ever see to the color called "olo".
To see "olo" you need a mad scientist to map your retina, individually identify each cone cell as one of 3 kinds - and then use lasers to deliver light exclusively to your "M" cones.
Done recently:
mathstodon.xyz/@johncarlosb...
To see "olo" you need a mad scientist to map your retina, individually identify each cone cell as one of 3 kinds - and then use lasers to deliver light exclusively to your "M" cones.
Done recently:
mathstodon.xyz/@johncarlosb...
John Carlos Baez (@[email protected])
Attached: 1 image
This may be the closest you'll ever see to the color with the ridiculous name of "olo".
To see true olo, you need a mad scientist to map your retina, individually identify each ...
mathstodon.xyz
November 12, 2025 at 9:41 PM
This is the closest you'll ever see to the color called "olo".
To see "olo" you need a mad scientist to map your retina, individually identify each cone cell as one of 3 kinds - and then use lasers to deliver light exclusively to your "M" cones.
Done recently:
mathstodon.xyz/@johncarlosb...
To see "olo" you need a mad scientist to map your retina, individually identify each cone cell as one of 3 kinds - and then use lasers to deliver light exclusively to your "M" cones.
Done recently:
mathstodon.xyz/@johncarlosb...
The weak nuclear force is all about qubits: for example, quarks come in 3 generations of "up" or "down" kinds.
The strong force is all about "qutrits".
Electromagnetism is about "quunits".
But what's a qubit really like? I'll explain it here!
www.youtube.com/watch?v=7Umq...
The strong force is all about "qutrits".
Electromagnetism is about "quunits".
But what's a qubit really like? I'll explain it here!
www.youtube.com/watch?v=7Umq...
Standard Model - Part 3: Qubits
YouTube video by John Baez
www.youtube.com
November 12, 2025 at 11:02 AM
The weak nuclear force is all about qubits: for example, quarks come in 3 generations of "up" or "down" kinds.
The strong force is all about "qutrits".
Electromagnetism is about "quunits".
But what's a qubit really like? I'll explain it here!
www.youtube.com/watch?v=7Umq...
The strong force is all about "qutrits".
Electromagnetism is about "quunits".
But what's a qubit really like? I'll explain it here!
www.youtube.com/watch?v=7Umq...
The most zoomed-in, highest-frame-rate movie of a solar eclipse ever taken from the Martian surface - in 2020.
Phobos is slowly drifting toward Mars. Tens of millions of years from now it will crash land.
Phobos is slowly drifting toward Mars. Tens of millions of years from now it will crash land.
November 11, 2025 at 9:33 PM
The most zoomed-in, highest-frame-rate movie of a solar eclipse ever taken from the Martian surface - in 2020.
Phobos is slowly drifting toward Mars. Tens of millions of years from now it will crash land.
Phobos is slowly drifting toward Mars. Tens of millions of years from now it will crash land.
When you repeatedly measure the positions of over a billion stars so accurately that you can see a star moving by an amount equal to the size of a pinhead on the Moon, as seen from Earth... you find amazing things!
It's great.
mathstodon.xyz/@johncarlosb...
It's great.
mathstodon.xyz/@johncarlosb...
John Carlos Baez (@[email protected])
Holy crap! The Gaia space telescope is expected to find 120,000 ± 22,000 planets orbiting other stars! Most will be super-Jupiters, because those are the easiest to find. But we'll know much more ...
mathstodon.xyz
November 8, 2025 at 10:07 AM
When you repeatedly measure the positions of over a billion stars so accurately that you can see a star moving by an amount equal to the size of a pinhead on the Moon, as seen from Earth... you find amazing things!
It's great.
mathstodon.xyz/@johncarlosb...
It's great.
mathstodon.xyz/@johncarlosb...
Lise Meitner, who discovered nuclear fission and did the experiments that led Pauli to postulate neutrinos, is one of my heroes. She had to work twice as hard for everything, and did so much.
I tell a bit of her story here:
mathstodon.xyz/@johncarlosb...
I tell a bit of her story here:
mathstodon.xyz/@johncarlosb...
John Carlos Baez (@[email protected])
Attached: 1 image
Lise Meitner, who discovered nuclear fission, is one of my heroes. She had to work twice as hard for everything, and did so much.
The Austrian government did not open the universi...
mathstodon.xyz
November 4, 2025 at 10:16 AM
Lise Meitner, who discovered nuclear fission and did the experiments that led Pauli to postulate neutrinos, is one of my heroes. She had to work twice as hard for everything, and did so much.
I tell a bit of her story here:
mathstodon.xyz/@johncarlosb...
I tell a bit of her story here:
mathstodon.xyz/@johncarlosb...
In quantum mechanics we say how an observable O(t) changes using the Heisenberg equation. But what if you've just got a Jordan algebra? No i, no commutator, just the Jordan product ∘. Then
dO(t)/dt = {A, O(t), B}
where {A,O,B} = (A∘O)∘B - A∘(O∘B). 😮
golem.ph.utexas.edu/category/202...
dO(t)/dt = {A, O(t), B}
where {A,O,B} = (A∘O)∘B - A∘(O∘B). 😮
golem.ph.utexas.edu/category/202...
November 2, 2025 at 4:42 PM
In quantum mechanics we say how an observable O(t) changes using the Heisenberg equation. But what if you've just got a Jordan algebra? No i, no commutator, just the Jordan product ∘. Then
dO(t)/dt = {A, O(t), B}
where {A,O,B} = (A∘O)∘B - A∘(O∘B). 😮
golem.ph.utexas.edu/category/202...
dO(t)/dt = {A, O(t), B}
where {A,O,B} = (A∘O)∘B - A∘(O∘B). 😮
golem.ph.utexas.edu/category/202...
Paulina Borsook got it before the rest of us:
"Every day, computers are making people easier to use."
mathstodon.xyz/@gilduran.co...
"Every day, computers are making people easier to use."
mathstodon.xyz/@gilduran.co...
Mathstodon
mathstodon.xyz
October 30, 2025 at 9:07 AM
Paulina Borsook got it before the rest of us:
"Every day, computers are making people easier to use."
mathstodon.xyz/@gilduran.co...
"Every day, computers are making people easier to use."
mathstodon.xyz/@gilduran.co...
Anthropic owes me - and my coauthors, and publishers - $9000 for books they ripped off. Check out the list and see how much they owe you:
secure.anthropiccopyrightsettlement.com/lookup
Details on how this works:
authorsguild.org/advocacy/art...
secure.anthropiccopyrightsettlement.com/lookup
Details on how this works:
authorsguild.org/advocacy/art...
Submit a Claim
secure.anthropiccopyrightsettlement.com
October 28, 2025 at 9:45 AM
Anthropic owes me - and my coauthors, and publishers - $9000 for books they ripped off. Check out the list and see how much they owe you:
secure.anthropiccopyrightsettlement.com/lookup
Details on how this works:
authorsguild.org/advocacy/art...
secure.anthropiccopyrightsettlement.com/lookup
Details on how this works:
authorsguild.org/advocacy/art...