Lightnews — Scholar-powered news

John C. Baez

@johncarlosbaez.bsky.social

410 followers 140 following 210 posts

Mathematical physicist

Posts Media Videos Starter Packs

Pinned

John C. Baez @johncarlosbaez.bsky.social · 13d

I'm trying to lose weight. I was so happy when I saw my local pastry shop sold negative-mass doughnuts. But what happened next really freaked me out.

(Negative mass in Newtonian mechanics, special relativity and relativistic quantum mechanics.)

www.youtube.com/watch?v=THT8...

Negative mass

YouTube video by John Baez

www.youtube.com

John C. Baez @johncarlosbaez.bsky.social · 14h

There are people who have been poisoned in this way: prompted with the phrase "quantum mechanics", they speak a bunch of nonsense.

John C. Baez @johncarlosbaez.bsky.social · 14h

250 documents with a keyword followed by gibberish, injected into the training of a large language model, can "poison" it - according to Anthropic.

www.anthropic.com/research/sma...

A small number of samples can poison LLMs of any size

Anthropic research on data-poisoning attacks in large language models

www.anthropic.com

1 2 7

John C. Baez @johncarlosbaez.bsky.social · 1d

It must have been so fun to first discover 'cathode rays' - now called electrons - and then 'anode rays' - positive ions, including protons - like this.

Crank up the voltage on an evacuated tube and get weird glows!

Anode ray tube showing the rays passing through the perforated cathode and causing the pink glow above it.

From Kkmurray, with CC license here:

https://commons.wikimedia.org/wiki/File:Anode_Ray_Tube.jpg

1 2

John C. Baez @johncarlosbaez.bsky.social · 1d

I think you have the power to remold people's perception of "hard SF" just by writing it in your own way. But does it really benefit you to brand yourself as working in this genre?

(I guess I'm naive about self-branding. I generally avoid it.)

John C. Baez @johncarlosbaez.bsky.social · 1d

Wow, it seems a black hole fell into a star and quickly at it all up, producing 3 big gamma ray bursts! First time we've seen this.

As I explain, it may have been a 'helium star': a blue giant star that had shot off all its outer layers, leaving its helium core.

mathstodon.xyz/@johncarlosb...

John Carlos Baez (@[email protected])

Attached: 1 image Wow. A black hole may have fallen into a star, eating it up and causing three big gamma ray bursts! Never seen before. The first gamma ray burst was detected by the Fermi Gamma...

mathstodon.xyz

John C. Baez @johncarlosbaez.bsky.social · 2d

It's good for the soul in small doses, but in large doses it can turn you into an analyst!

John C. Baez @johncarlosbaez.bsky.social · 3d

I have Vinberg's paper now, thanks. I've disabled chats, which I guess are the same as pms.

John C. Baez @johncarlosbaez.bsky.social · 3d

Yes, I think so... and I find these less attractive for various reasons.

John C. Baez @johncarlosbaez.bsky.social · 3d

Yes, couplings - or as I said in the alt text, "interactions".

This diagram was best back when we thought neutrinos were massless. Now we know they have mass, but we don't know *for sure* that they're coupled to the Higgs. I'd have drawn a blue curve with a question mark next to it.

John C. Baez @johncarlosbaez.bsky.social · 3d

Swiping left on the blue dot does nothing; clicking on it takes me to the stuff below.

Clicking on "Go to account settings" then takes me to a place where I can do "age assurance".

John C. Baez @johncarlosbaez.bsky.social · 3d

People who don't like dark matter have probably never thought about how hard it would be to go beyond the Standard Model without some clue like dark matter.

A good theory might explain dark matter and also *simplify* the Standard Model. Simpler theories often have more particles.

A chart of Standard Model particles and their interactions: leptons, quarks, gluon, photon, Higgs boson and weak bosons (W and Z).

2 5

John C. Baez @johncarlosbaez.bsky.social · 3d

Thanks, I'll try that. It's so annoying that there seems to be no way to delete chats!

John C. Baez @johncarlosbaez.bsky.social · 4d

In the old days, when I first visited Hong Kong, they had illegal bus services! Slowly they became legalized....

trippin.world/feature/red-...

Why You Need to Take a Red Mini Bus in Hong Kong

You may think hailing one of the many taxis off the road is the right way to get around in Hong Kong, but locals might disagree.

trippin.world

John C. Baez @johncarlosbaez.bsky.social · 4d

Swirl: a swirling piece of music from my album Treq Lila, made by "breeding" cellular automata in Steve Wolfram's WolframTones system:

soundcloud.com/john-c-baez/...

Art by Greg Egan.

Swirl

From my album Treq Lila, made by

soundcloud.com

John C. Baez @johncarlosbaez.bsky.social · 4d

If anyone can give me Vinberg's

The theory of convex homogeneous cones, Trans. Moscow Math. Soc., 12 (1965) 340–403.

please do! The best source I have now is Chua's paper on T-algebras and convex homogeneous cones:

dr.ntu.edu.sg/server/api/c...

(2/2)

dr.ntu.edu.sg

1 1

John C. Baez @johncarlosbaez.bsky.social · 4d

The exceptional Jordan algebra 𝔥₃(𝕆) is connected to quantum logic and perhaps also the Standard Model (see below). More complicated algebras like 𝔥₃(𝕆⊗ℍ) aren't Jordan algebras, but they're Vinberg T-algebras and still connected to quantum logic!

(1/2)

golem.ph.utexas.edu/category/202...

A Complex Qutrit Inside an Octonionic One | The n-Category Café

golem.ph.utexas.edu

1 2

John C. Baez @johncarlosbaez.bsky.social · 4d

My crazy new hope about quantum logic is that it's been inconsequential for "real-world physics" mainly because we haven't gone far enough down the rabbit-hole. I am now going down the rabbit-hole.

(Vinberg's special T-algebras, here I come!)

1 10

John C. Baez @johncarlosbaez.bsky.social · 6d

More like a tsunami, as far as students see it.

John C. Baez @johncarlosbaez.bsky.social · 6d

Grothendieck wrote of how the gradual buildup of results in algebraic geometry is like a slowly rising sea.

But from the student's perspective, it looks like this. 😆

Hokusai's famous print "The Great Wave off Kanagawa", showing three boats moving through a storm-tossed sea, with a large, cresting wave forming a spiral in the centre over the boats and Mount Fuji in the background.

1 1 9

John C. Baez @johncarlosbaez.bsky.social · 6d

Grothendieck talked about how the sea of results slowly rises, almost imperceptibly. This book cover makes it look pretty threatening. Which is how students perceive Grothendieck's work. 😆

John C. Baez @johncarlosbaez.bsky.social · 6d

So someone thinks science isn't creative work? I'm confused.

1 1

John C. Baez @johncarlosbaez.bsky.social · 7d

I don't understand it, but this article claims to explain it.

"This article outlines the use of the Brunauer-Emmett-Teller (BET) method and Barrett-Joyner-Halenda (BJH) method for the calculation of surface area and pore volume, respectively...."

app.jove.com/t/65716/dete...

Determining Surface Areas and Pore Volumes of Metal-Organic Frameworks

Georgia Institute of Technology. This article describes the use of nitrogen porosimetry to characterize metal-organic frameworks, using UiO-66 as a representative material.

app.jove.com

John C. Baez @johncarlosbaez.bsky.social · 7d

In principle yes, but it seems they haven't reached the goals people want for them.

chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/...

Metal‐Organic Frameworks (MOFs) As Hydrogen Storage Materials At Near‐Ambient Temperature

Hydrogen as is difficult to store in significant quantities via physical methods especially at near-ambient temperatures (248–373 K). Metal-organic frameworks (MOFs) have the potential to increase hy...

chemistry-europe.onlinelibrary.wiley.com

John C. Baez @johncarlosbaez.bsky.social · 7d

So I wrote a few blog articles. But I decided, unsurprisingly, that they wouldn't scale up enough to do any good for climate change. So I quit, and never got paid for the articles I wrote.

Still, they are a cool technology and have lots of potential uses.

Synthesis of the MIL-101 metal-organic framework. Each green octahedron consists of one Cr atom in the center and six oxygen atoms (red balls) at the corners.

1 3

John C. Baez @johncarlosbaez.bsky.social · 7d

In 2019, someone offered to pay me to publicize their business involving metal-organic frameworks. The idea proposed to me was that these could be used to soak up greenhouse gases, and that I should blog about this.

johncarlosbaez.wordpress.com/2019/03/11/m...

Metal-Organic Frameworks

I’ve been talking about new technologies for fighting climate change, with an emphasis on negative carbon emissions. Now let’s begin looking at one technology in more detail. This will …

johncarlosbaez.wordpress.com

1 1