John C. Baez's Blog, page 48

Climate Technology Primer (Part 2)

Here’s the second of a series of blog articles:

• Adam Marblestone, Climate technology primer (2/3): CO2 removal.

The first covered the basics of climate science as related to global warming. This one moves to consider technologies for removing carbon dioxide from the air.

I hope you keep the following warning in mind as you read on:

I’m focused here on trying to understand the narrowly technical aspects, not on the political aspects, despite those being crucial. This is meant to be a review...

Foundations of Math and Physics One Century After Hilbert

I wrote a review of this book with chapters by Penrose, Witten, Connes, Atiyah, Smolin and others:

• John Baez, review of Foundations of Mathematics and Physics One Century After Hilbert: New Perspectives, edited by Joseph Kouneiher, Notices of the American Mathematical Society 66 no. 11 (November 2019), 1690–1692.

It gave me a chance to say a bit—just a tiny bit—about the current state of fundamental physics and the foundations of mathematics.

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Quantales from Petri Nets

A referee pointed out this paper to me:

• Uffe Engberg and Glynn Winskel, Petri nets as models of linear logic, Colloquium on Trees in Algebra and Programming, Springer, Berlin, 1990.

It contains a nice observation: we can get a commutative quantale from any Petri net.

I’ll explain how in a minute. But first, what does have to do with linear logic?

In linear logic, propositions form a category where the morphisms are proofs and we have two kinds of ‘and’: , which is a cartesian product on thi...

Climate Technology Primer (Part 1)

Here’s the first of a series of blog articles on how technology can help address climate change:

• Adam Marblestone, Climate technology primer (1/3): basics.

Adam Marblestone is a research scientist at Google DeepMind studying connections between neuroscience and artificial intelligence. Previously, he was Chief Strategy Officer of the brain-computer interface company Kernel, and a research scientist in Ed Boyden’s Synthetic Neurobiology Group at MIT working to develop new technologies for br...

Applied Category Theory Meeting at UCR (Part 2)

 

Joe Moeller and I have finalized the schedule of this meeting on applied category theory:

• Applied Category Theory, special session of the Fall Western Sectional Meeting of the AMS, U. C. Riverside, Riverside, California, 9–10 November 2019.

It’s going to be a really cool meeting, with talks on everything from brakes to bicategories, from quantum physics to social networks, and more—with the power of category theory as a unifying theme!

You can get information on registration, hotels a...

Ordovician Meteor Event

About 1/3 of the meteorites hitting Earth today come from one source: the L chondrite parent body, an asteroid 100–150 kilometers across that was smashed in an impact 468 million years ago. This was biggest asteroid collision in the last 3 billion years!

Here is an L-chondrite:

A chondrite is a stony, non-metallic meteorite that was formed form small grains of dust present in the early Solar System. They are the most common kind of meteorite—and the three most common kinds, each with its own...

Rethinking Universities

Izabella Łaba is a mathematician at the University of British Columbia. She works on harmonic analysis, geometric measure theory and additive combinatorics. But this talk is on a different topic:

• Izabella Łaba, Rethinking universities in an era of climate change.

You should read her slides, but she’s given me permission to quote them extensively here. She starts by saying:

This talk came from my frustration with how universities are
responding to climate emergency.

• Corporate-style “sustai...

Vaclav Smil on Growth

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Yet another interesting book I haven’t read yet:

• Vaclav Smil, Growth: From Microorganisms to Megacities, MIT Press, Cambridge, 2019.

As I hope you know, Vaclav Smil is an expert on energy, food, population, and economics, who assembles and analyzes data in fact-filled books like Energy and Civilization: a History.  Bill Gates has said “I wait for new Smil books the way some people wait for the next ‘Star Wars’ movie.”

He was interviewed here:

• Jonathan Watts, Vaclav Smil: ‘Growth must end...

Divesting

Christian Williams

John always tells me to write short, sweet, and clear. Knowing that his advice is supreme on these matters, I’ll try to write mini-posts in between the bigger ones. But… not this time – the topic is too good.

[image error](Dispossess of property/authority. Say it, sound smart.)

…..

Work smarter, not (just) harder.

Today I got an email from Bill McKibben, founder of 350.org. (350 parts per million, the concentration of CO2 considered a “safe upper limit” for Earth, by NASA scientists Jam...

Klein on the Green New Deal

I’m going to try to post more short news items. For example, here’s a new book I haven’t read yet:

• Naomi Klein, On Fire: The (Burning) Case for a Green New Deal, Simon and Schuster, 2019.

I think she’s right when she says this:

I feel confident in saying that a climate-disrupted future is a bleak and an austere future, one capable of turning all our material possessions into rubble or ash with terrifying speed. We can pretend that extending the status quo into the future, unchanged, is one...