Theoretical Physics in the 21st Century

1 March, 2021

I gave a talk at the Zürich Theoretical Physics Colloquium for Sustainability Week 2021. I was excited to get a chance to speak both about the future of theoretical physics and the climate crisis.

You can see a video of my talk, and also my slides: links in blue on my slides lead to more information.

Title: Theoretical Physics in the 21st Century.

Time: Monday, 8 March 2021, 15:45 UTC (that is, Greenwich Mean Time).

Abstract: The 20th century was the century of physics. What about the 21st? Though progress on some old problems is frustratingly slow, exciting new questions are emerging in condensed matter physics, nonequilibrium thermodynamics and other fields. And most of all, the 21st century is the dawn of the Anthropocene, in which we will adapt to the realities of life on a finite-​sized planet. How can physicists help here?

Hosts: Niklas Beisert, Anna Knörr.

Geoengineering – The Tipping Point

10 February, 2021

Back in 2013 I wrote about how we are approaching a tipping point, where public opinion on geoengineering suddenly starts to shift:

Many express the fear that merely researching geoengineering schemes will automatically legitimate them, however hare-brained they are. There’s some merit to that fear. But I suspect that public opinion on geoengineering will suddenly tip from “unthinkable!” to “let’s do it now!” as soon as global warming becomes perceived as a real and present threat. This is especially true because oil, coal and gas companies have a big interest in finding solutions to global warming that don’t make them stop digging.

I argued that because of this, we need to start thinking hard about the issues now.

I think we should start serious research on geoengineering schemes, including actual experiments, not just calculations and simulations. I think we should do this with an open mind about whether we’ll decide that these schemes are good ideas or bad. Either way, we need to learn more about them. Simultaneously, we need an intelligent, well-informed debate about the many ethical, legal and political aspects.

I think this tipping point is getting very close now: close enough to be discussed in popular media. Like this:

• Ezra Klein, Should we dim the Sun? Will we even have a choice?, New York Times, 9 February 2021.

This is Ezra Klein interviewing Elizabeth Kolbert, author of The Sixth Extinction. She just wrote a book Under a White Sky: The Nature of the Future.. It’s about how we’ve altered nature so much, and are so trapped in relying on this, that there’s no way to go back to the good old days. At this point, any attempt to ‘go back’ amounts to going forward in another direction.

I’ll quote a bit:

Ezra Klein: Your book reads as an argument that we are past the point when we have the luxury of saying that things like geoengineering are off limits because we shouldn’t change the world that much. We’ve already changed it so much that the unthinkable now has to be thought.

Elizabeth Kolbert: I think that’s a reasonable interpretation. I think you could read it as, we are past the point of having that luxury. You could also read it as a species that has managed to muck up the atmosphere one way thinking about mucking up the atmosphere another way — what could possibly go wrong? I think those are both very valid readings.

Ezra Klein: You have a wonderful quote in the geoengineering chapter of your book from Andy Parker, who is a project director for the Solar Radiation Management Governance Initiative. He says, “We live in a world where deliberately dimming the [expletive] sun might be less risky than not doing it.” That feels like quite an indictment of the human race and where we’ve gotten ourselves to with all our knowledge and all our power.

Elizabeth Kolbert: I think that does sort of sum things up. We are in this very deep — there are only wrong answers, only hard choices at this point. Nothing easy from here on in.

Ezra Klein: What do you think of geoengineering?

Elizabeth Kolbert: I very consciously avoided coming down very clearly on that. But some very, very smart people are thinking about it and are very worried that it may be our best option at a certain point. And I think they may, unfortunately, be right — but wow, it’s dimming the [expletive] sun, you know?

Ezra Klein: I think how people feel about geoengineering depends on how they feel about the traditional political pathway. Do you think there is a significant chance that traditional politics are going to do enough to keep us under 2 degrees of warming?

Elizabeth Kolbert: Many, many scientists and many nations — especially the low-lying island nations that could disappear between here and 2 degrees — would say that’s really too high. So there’s a stretch goal, if you want, in the Paris accord of 1.5 degrees.

If you’re going to be honest about it, I think you have to say we’re basically at 1.5 degrees now. So that is not just a hard goal to reach; it’s getting to be almost geophysically impossible. Now, 2 degrees — presumably, it is still physically possible to do it.

Then that gets to the point you’re making: Is the world set up to do this? And the problem is not just that in the U.S. we are legislatively gridlocked — that, so far at least, we have been really incapable of taking significant action. And I do want to add, the U.S. is still the biggest single source of greenhouse gases that are up there in the atmosphere right now.

But then you have to look all around the world at all of the major players in this drama — China, which is now the single biggest emitter on an annual basis; the E.U., which is a very big emitter; India, which is increasingly a large emitter. So you have to ask, are we all going to get our act together?

Ezra Klein: One of the questions that I struggle with most in my own work right now is, what do you do if you believe that it is no longer politically plausible that normal politics will get to a reasonable outcome here? Sometimes I think about technological solutions — huge amounts of money being spent on not just renewables, but potentially studying things like geoengineering. Sometimes I wonder about things that are somewhere between political activism and extra-political. Where are you on this?

Elizabeth Kolbert: When we get into the “what could happen now owing to our failures,” that’s certainly where geoengineering comes in. A lot of very smart people are saying, look at the political system. It’s just not capable of moving fast enough. And the last 30 years are a pretty depressing proof of that.

And, as you say, you’re led either to a technofix or you’re led to a carbon dictatorship. I don’t know what you’re led to if you say, we just are incapable of moving fast enough under politics as they are. And the point, I think, that’s really important is on some level, it’s unknowable. How people will react all around the world, this is going to affect everyone. It’s going to affect some people much more brutally than others.

The Dome Fire

13 December, 2020

This August a fire swept through the Mojave National Preserve in southern California and killed about a million Joshua trees. Let us take a moment to mourn them, along with the ancient giant sequouias that we also lost this year.

(The article has a subheading that mistakenly says “countless ancient redwoods” also died, but the article itself does not claim this, though it has a section on coastal redwoods and the fires affecting them.)

• John Branch, They’re among the world’s oldest living things. The climate crisis is killing them, New York Times, December 2020.

This lavishly illustrated article talks about all three species. I’ll just quote the part on Joshua trees, since they live pretty close to here.

Mojave National Preserve, Calif. — On the August day when fire broke out on Cima Dome in the Mojave National Preserve, the California desert already was making international headlines. The thermometer at nearby Death Valley had reached 130 degrees, the highest temperature reliably recorded on Earth.

As photos of tourists smiling at the thermometer ricocheted around the world — a paradoxical bit of gee-whiz glee on a day portending a dire future — a million Joshua trees were on fire.

Cima Dome is a broad mound, a gentle and symmetrical arc on the vast desert horizon. It is visible from the interstate connecting Los Angeles and Las Vegas. Scientists considered it home to the world’s densest concentration of Joshua trees.

“To the untrained eye or the person not familiar with this region, most wouldn’t even notice it as they go by at 90 m.p.h.,” said Todd Esque, a desert ecologist for the United States Geological Survey. “But for those who do know, this is a huge loss.”

Joshua trees—a yucca, not a tree, named by Mormon settlers—already teeter toward trouble. Their range is shrinking, and they are not well-suited to outrun the quickening pace of climate change. Scientists worry that future visitors will find no Joshua trees in Joshua Tree National Park, the way some worry that Glacier National Park will be devoid of year-round ice.

“It’s a possibility,” Dr. Esque said.

Now wildfires, scarcely a threat historically, are taking out huge swaths at once, aided by climate change and invasive grasses.

The Dome Fire consumed 43,273 acres and killed most of the estimated 1.3 million Joshua trees it burned, according to Mr. Kaiser, the vegetation program manager for Mojave National Preserve.

“Cima Dome was a model for where the Joshua tree could persist for the next 100 years,” Mr. Kaiser said. “It was a beautiful, lush, decadent Joshua tree forest. But they’re wiped out.”

While there are plans to replant the millions of dead with thousands of young Joshua trees, “It’ll never come back like it was,” Mr. Kaiser said. “Not with climate change.”

Joshua trees can grow more than 40 feet tall with spiky, Seussian eccentricity. They typically live about 150 years.

But their range is shrinking faster than the trees can spread to more livable climes—higher in elevation and latitude, generally. The species is thwarted by slow migration (their large seeds, once transported by ground sloths that are now extinct, do not travel far from where they fall) and the overall population appears to be aging. Even at Cima Dome, there were relatively few young Joshua trees.

Those are persistent threats, too. Humans chop down Joshua trees to make room for neighborhoods, roads, even solar farms. And with Joshua trees often sharing the landscape with ranching, invasive grasses are fueling more fires than ever.

While the Dome Fire was shocking in its scope and ferocity, it was not surprising to the scientists who know the area best. “This was just a fire waiting to happen,” said Debra Hughson, chief of science and resource stewardship at Mojave National Preserve.

For more than a century, until 2002, cattle grazed on Cima Dome. Among the legacy of livestock is invasive perennial grasses like red brome. Weirdly, though, those same grasses may have helped the Joshua tree flourish.

Young Joshua trees need a nurse plant to hide under, and the prickly, woody blackbrush—unappetizing to livestock—is a perfect partner. As cattle chomped on grass, leaving vegetation sparse enough to prevent potential fires from spreading, Joshua trees took hold on Cima Dome more than in other places.

“A lot of what we were calling a year ago ‘the largest and densest Joshua Tree forest in the world’ probably didn’t exist in the early part of the 20th century,” Dr. Hughson said.

And after cattle were banned, and the invasive grasses grew uninterrupted, “It was just waiting for a spark,” she said.

The spark came in August, with a lightning strike. With resources stretched because of so many other California fires, the Dome Fire spread uncontrolled. It jumped from Joshua tree to Joshua tree and across park roads and fire lines, fueled by winds that became swirling firenados.

In two days, the blaze had done almost unimaginable damage.

“I was preparing myself for the worst,” Mr. Kaiser said as he toured the burn area. “And it pretty much was the worst.”

Reframing Superintelligence

30 September, 2020

Eric Drexler has a document calling for a view of superintelligent systems where instead of focusing on agents or minds we should focus on intelligent services. This is, of course, the approach taken by industrial AI so far. But the idea of a superintelligent agent with its own personality, desires and motivations still has a strong grip on our fantasies of the future.

• Eric Drexler, Reframing Superintelligence: Comprehensive AI Services as General Intelligence, Technical Report #2019-1, Future of Humanity Institute.

His abstract begins thus:

Studies of superintelligent-level systems have typically posited AI functionality that plays the role of a mind in a rational utility-directed agent, and hence employ an abstraction initially developed as an idealized model of human decision makers. Today, developments in AI technology highlight intelligent systems that are quite unlike minds, and provide a basis for a different approach to understanding them.

The desire to build an independent self-motivated superintelligent agents (“AGI”: artificial general intelligence) still beckons to many. But Drexler suggests treating this as a deviant branch we should avoid. He instead wants us to focus on “CAIS”: comprehensive AI services.

First, we don’t have any practical reason to want AGI:

In practical terms, we value potential AI systems for what they could do, whether driving a car, designing a spacecraft, caring for a patient, disarming an opponent, proving a theorem, or writing a symphony. Scientific curiosity and long-standing aspirations will encourage the development of AGI agents with open-ended, self-directed, human-like capabilities, but the more powerful drives of military competition, economic competition, and improving human welfare do not in themselves call for such agents. What matters in practical terms are the concrete AI services provided (their scope, quality, and reliability) and the ease or difficulty of acquiring them (in terms of time, cost,and human effort).

Second, it’s harder to create agents with their own motives than to create services. And third, they are more risky.

But there’s no sharp line between “AI as service” and “AI as agent”, so endless care is required if we want CAIS but not AGI:

There is no bright line between safe CAI services and unsafe AGI agents, and AGI is perhaps best regarded as a potential branch from an R&D-automation/CAIS path. To continue along safe paths from today’s early AI R&D automation to superintelligent-level CAIS calls for an improved understanding of the preconditions for AI risk, while for any given level ofsafety, a better understanding of risk will widen the scope of known-safe system architectures and capabilities. The analysis presented above suggests that CAIS models of the emergence of superintelligent-level AI capabilities, including AGI, should be given substantial and arguably predominant weight in considering questions of AI safety and strategy.

Although it is important to distinguish between pools of AI services and classic conceptions of integrated, opaque, utility-maximizing agents, we should be alert to the potential for coupled AI services to develop emergent, unintended,and potentially risky agent-like behaviors. Because there is no bright line between agents and non-agents, or between rational utility maximization and reactive behaviors shaped by blind evolution, avoiding risky behaviors calls for at least two complementary perspectives: both (1) design-oriented studies that can guide implementation of systems that will provide requisite degrees of e.g., stability, reliability, and transparency, and (2) agent-oriented studies support design by exploring the characteristics of systems that could display emergent, unintended, and potentially risky agent-like behaviors. The possibility (or likelihood) of humans implementing highly-adaptive agents that pursue open-ended goals in the world (e.g., money-maximizers) presents particularly difficult problems.

Perhaps “slippage” toward agency is a bigger risk than the deliberate creation of a superintelligent agent. I feel extremely unconfident in the ability of humans to successfully manage anything, except for short periods of time. I’m not confident in any superintelligence being better at this, either: they could be better at managing things, but they’d have more to manage. Drexler writes:

Superintelligent-level aid in understanding and implementing solutions to the AGI control problem could greatly improve our strategic position.

and while this is true, this offers even more opportunity for “slippage”.

I suspect that whatever can go wrong eventually does. Luckily a lot goes right, too. We fumble, stumble and tumble forward into the future.

Can We Fix The Air?

12 January, 2020

I published a slightly different version of this article in Nautilus on November 28, 2019.

Water rushes into Venice’s city council chamber just minutes after the local government rejects measures to combat climate change. Wildfires consume eastern Australia as fire danger soars past “severe” and “extreme” to “catastrophic” in parts of New South Wales. Ice levels in the Chukchi Sea, north of Alaska, hit record lows. England sees floods all across the country. And that’s just this week, as I write this.

Human-caused climate change, and the disasters it brings, are here. In fact, they’re just getting started. What will things be like in another decade, or century?

It depends on what we do. If our goal is to stop global warming, the best way is to cut carbon emissions now—to zero. The United Kingdom, Denmark, and Norway have passed laws requiring net zero emissions by 2050. Sweden is aiming at 2045. But the biggest emitters—China, the United States, and India—are dragging their heels. So to keep global warming below 2 degrees Celsius over pre-industrial levels by 2100, it’s becoming more and more likely that we’ll need negative carbon emissions:

That is, we’ll need to fix the air. We’ll need to suck more carbon dioxide out of the atmosphere than we put in.

This may seem like a laughably ambitious goal. Can we actually do it? Or is it just a fantasy? I want to give you a sense of what it would take. But first, here’s one reason this matters. Most people don’t realize that large negative carbon emissions are assumed in many of the more optimistic climate scenarios. Even some policymakers tasked with dealing with climate change don’t know this.

In 2016, climate scientists Kevin Anderson and Glen Peters published a paper on this topic, called “The trouble with negative emissions.” The title is a bit misleading, since they are not against negative emissions. They are against lulling ourselves into complacency by making plans that rely on negative emissions—because we don’t really know how to achieve them at the necessary scale. We could be caught in a serious bind, with the poorest among us taking the biggest hit.

So, how much negative carbon emissions do we need to stay below 2 degrees Celsius of warming, and how people are hoping to achieve them? Let’s dive in!

In 2018, humans put about 37 billion tonnes of carbon dioxide into the air. A “tonne” is a metric ton, a bit larger than a US ton. Since the oxygen is not the problem—carbon dioxide consisting of one atom of carbon and two of oxygen—it might make more sense to count tonnes of carbon. But it’s customary to keep track of carbon by its carbon dioxide equivalent, so I’ll do that here. The National Academy of Sciences says that to keep global warming below 2 degrees Celsius by the century’s end, we will probably need to be removing about 10 billion tonnes of carbon dioxide from the air each year by 2050, and double that by 2100. How could we do this?

Whenever I talk about this, I get suggestions. Many ignore the sheer scale of the problem. For example, a company called Climeworks is building machines that suck carbon dioxide out of the air using a chemical process. They’re hoping to use these gadgets to make carbonated water for soft drinks—or create greenhouses that have lots of carbon dioxide in the air, for tastier vegetables. This sounds very exciting…until you learn that currently their method of getting carbon dioxide costs about $500 per ton. It’s much cheaper to make the stuff in other ways; beverage-grade carbon dioxide costs about a fifth as much. But even if they bring down the price and become competitive in their chosen markets, greenhouses and carbonation use only 6 million tonnes of carbon dioxide annually. This is puny compared to the amount we need to remove.

Thus, the right way to think of Climeworks is as a tentative first step toward a technology that might someday be useful for fighting global warming—but only if it can be dramatically scaled up and made much cheaper. The idea of finding commercial uses for carbon dioxide as a stepping-stone, a way to start developing technologies and bringing prices down, is attractive. But it’s different from finding commercial uses that could make a serious dent in our carbon emissions problem.

Here’s another example: using carbon dioxide from the air to make plastics. There’s a company called RenewCO2 that wants to do this. But even ignoring the cost, it’s clear that such a scheme could remove 10 billion tonnes of carbon dioxide from the air each year only if we drastically ramped up our production of plastics. In 2018, we made about 360 million tonnes of plastic. So, we’d have to boost plastic production almost ten-fold. Furthermore, we’d have to make all this plastic without massively increasing our use of fossil fuels. And that’s a general issue with schemes to fix the air. If we could generate a huge abundance of power in a carbon-free way—say from nuclear, solar, or wind—we could use some of that power to remove carbon dioxide from the atmosphere. But for the short term, a better use of that power is to retire carbon-burning power plants. Thus, while we can dream about energy-intensive methods of fixing the air, they will only come into their own—if ever—later in the century.

If plastics aren’t big enough to eat up 10 billion tonnes of carbon dioxide per year, what comes closer? Agriculture. I’m having trouble finding the latest data, but in 2004 the world created roughly 5 billion tonnes of “crop residue”: stems, leaves, and such left over from growing food. If we could dispose of most of this residue in a way that would sequester the carbon, that would count as serious progress. Indeed, environmental engineer Stuart Strand and physicist Gregory Benford—also a noted science fiction writer—have teamed up to study what would happen if we dumped bales of crop residue on the ocean floor. Even though this stuff would rot, it seems that the gases produced will take hundreds of years to resurface. And there’s plenty of room on the ocean floor.

Short of a massive operation to sink crop residues to the bottom of the sea, there are still many other ways to improve agriculture so that the soil accumulates more carbon. For example, tilling the land less reduces the rate at which organic matter decays and carbon goes back into the air. You can actually fertilize the land with half-burnt plant material full of carbon, called “biochar.” Planting crops with bigger roots, or switching from annual crops to perennials, also helps. These are just a few of the good ideas people have had. While agriculture and soil science are complex, and you probably don’t want to get into the weeds on this, the National Academy of Sciences estimates that we could draw down 3 billion tonnes of carbon dioxide per year from improved agriculture. That’s huge.

Having mentioned agriculture, it’s time to talk about forests. Everyone loves trees. However, it’s worth noting that a mature forest doesn’t keep on pulling down carbon at a substantial rate forever. Yes, carbon from the air goes to form wood and organic material in the soil. But decaying wood and organic material releases carbon back into the air. A climax forest is close to a steady state: the rate at which it removes carbon from the air is roughly equal to the rate at which it releases this carbon. So, the time when a forest pulls down the most carbon is when it’s first growing.

In July 2019, a paper in Science argued that the Earth has room for almost 4 million square miles of new forests. The authors claimed that as these new trees grow, they could pull down about 730 billion tonnes of carbon dioxide.

At first this sounds great. But remember, we are putting out 37 billion tonnes a year. So, the claim is that if we plant new forests over an area somewhat larger than the US, they will absorb the equivalent of roughly 20 years of carbon emissions. In short, this heroic endeavor would buy us time, but it wouldn’t be a permanent solution. Worse, many other authors have argued that the Science paper was overly optimistic. One rebuttal points out that it mistakenly assumed treeless areas have no organic carbon in the soil already. It also counted on a large increase of forests in regions that are now grassland or savanna. With such corrections made, it’s possible that new forests could only pull down at most 150 billion tonnes of carbon dioxide.

That’s still a lot. But getting people to plant vast new forests will be hard. Working with more realistic assumptions, the National Academy of Sciences says that in the short term we could draw down 2.5 billion tonnes of carbon dioxide per year by planting new forests and better managing existing ones. In short: If we push really hard, better agriculture and forestry could pull 5.5 billion tonnes of carbon dioxide from the air each year. One great advantage of both these methods is that they harness the marvelous ability of plants to turn carbon dioxide into complex organic compounds in a solar-powered way—much better than any technology humans have devised so far. If we ever invent new technologies that do better, it’ll probably be because we’ve learned some tricks from our green friends.

And here’s another way plants can help: biofuels. If we burn fuels that come from plants, we’re taking carbon out of the atmosphere and putting it right back in: net zero carbon emissions, roughly speaking. That’s better than fossil fuels, where we dig carbon up from the ground and burn it. But it would be even better if we could burn plants as fuels but then capture the carbon dioxide, compress it, and pump it underground into depleted oil and gas fields, unmineable coal seams, and the like.

To do this, we probably shouldn’t cut down forests to clear space for crops that we burn. Turning corn into ethanol is also rather inefficient, though the corn lobby in the U.S. has persuaded the government to spend lots of money on this, and about 40 percent of all corn grown in the U.S. now gets used this way. Suppose we just took all available agricultural, forestry, and municipal waste, like lawn trimmings, food waste, and such, to facilities able to burn it and pump the carbon dioxide underground. All this stuff ultimately comes from plants sucking carbon from the air. So, how much carbon dioxide could we pull out of the atmosphere this way? The National Academy of Sciences says up to 5.2 billion tonnes per year.

Of course, we can’t do this and also sink all agricultural waste into the ocean—that’s just another way of dealing with the same stuff. Furthermore, this high-end figure would require immensely better organization than we’ve been able to achieve so far. And there are risks involved in pumping lots of carbon dioxide underground.

What other activities could draw down lots of carbon? It pays to look at the biggest human industries: biggest, that is, in terms of sheer mass being processed. For example, we make lots of cement. Global cement production in 2017 was about 4.5 billion tons, with China making more than the rest of the world combined, and a large uncertainty in how much they made. As far as I know, only digging up and burning carbon is bigger: for example, 7.7 billion tons of coal is being mined per year.

Right now cement is part of the problem: To make the most commonly used kind we heat limestone until it releases carbon dioxide and becomes “quicklime.” Only about 7 percent of the total carbon we emit worldwide comes from this process—but that still counts for more than the entire aviation industry. Some scientists have invented cement that absorbs carbon dioxide as it dries. It has not yet caught on commercially, but the pressure on the industry is increasing. If we could somehow replace cement with a substance made mostly of carbon pulled from the atmosphere, and do it in an economically viable way, that would be huge. But this takes us into the realm of technologies that haven’t been invented yet.

New technologies may in fact hold the key to the problem. In the second half of the century we should be doing things that we can’t even dream of yet. In the next century, even more so. But it takes time to perfect and scale up new technologies. So it makes sense to barrel ahead with what we can do now, then shift gears as other methods become practical. Merely waiting and hoping is not wise.

Totaling up some of the options I’ve listed, we could draw down 1 billion tonnes of carbon dioxide by planting trees, 1.5 billion by better forest management, 3 billion by better agricultural practices, and up to 5.2 billion by biofuels with carbon capture. This adds up to over 10 billion tonnes per year. It’s not nearly enough to cancel the 37 billion tonnes we’re dumping into the air each year now. But combined with strenuous efforts to cut emissions, we might squeak by, and keep global warming below 2 degrees Celsius.

Even if we try, we are far from guaranteed to succeed—Anderson and Peters are right to warn about this. But will we even try? This is more a matter of politics and economics than of science and technology. The engineer Saul Griffith said that dealing with global warming is not like the Manhattan Project—it’s like the whole of World War II but with everyone on the same side. He was half right: We are not all on the same side. Not yet, anyway. Getting leaders who are inspired by these huge challenges, rather than burying their heads in the sand, would be a big step in the right direction.

Climate Technology Primer (Part 1)

5 October, 2019

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 brain circuit mapping. He also helped to start companies like BioBright, and advised foundations such as the Open Philanthropy Project.

Now, like many of us, he’s thinking about climate change, and what to do about it. He writes:

In this first of three posts, I attempt an outsider’s summary of the basic physics/chemistry/biology of the climate system, focused on back of the envelope calculations where possible. At the end, I comment a bit about technological approaches for emissions reductions. Future posts will include a review of the science behind negative emissions technologies, as well as the science (with plenty of caveats, don’t worry) behind more controversial potential solar radiation management approaches. This first post should be very basic for anyone “in the know” about energy, but I wanted to cover the basics before jumping into carbon sequestration technologies.

Check it out! I like the focus on “back of the envelope” calculations because they serve as useful sanity checks for more complicated models… and also provide a useful vaccination against the common denialist argument “all the predictions rely on complicated computer models that could be completely wrong, so why should I believe them?” It’s a sad fact that one of the things we need to do is make sure most technically literate people have a basic understanding of climate science, to help provide ‘herd immunity’ to everyone else.

The ultimate goal here, though, is to think about “what can technology do about climate change?”

Klein on the Green New Deal

14 September, 2019

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 of the options available to us. But that is a fantasy. Change is coming one way or another. Our choice is whether we try to shape that change to the maximum benefit of all or wait passively as the forces of climate disaster, scarcity, and fear of the “other” fundamentally reshape us.

Nonetheless Robert Jensen argues that the book is too “inspiring”, in the sense of unrealistic optimism:

• Robert Jensen, The danger of inspiration: a review of On Fire: The (Burning) Case for a Green New Deal, Resilience, 10 September 2019.

Let me quote him:

On Fire focuses primarily on the climate crisis and the Green New Deal’s vision, which is widely assailed as too radical by the two different kinds of climate-change deniers in the United States today—one that denies the conclusions of climate science and another that denies the implications of that science. The first, based in the Republican Party, is committed to a full-throated defense of our pathological economic system. The second, articulated by the few remaining moderate Republicans and most mainstream Democrats, imagines that market-based tinkering to mitigate the pathology is adequate.

Thankfully, other approaches exist. The most prominent in the United States is the Green New Deal’s call for legislation that recognizes the severity of the ecological crises while advocating for economic equality and social justice. Supporters come from varied backgrounds, but all are happy to critique and modify, or even scrap, capitalism. Avoiding dogmatic slogans or revolutionary rhetoric, Klein writes realistically about moving toward a socialist (or, perhaps, socialist-like) future, using available tools involving “public infrastructure, economic planning, corporate regulation, international trade, consumption, and taxation” to steer out of the existing debacle.

One of the strengths of Klein’s blunt talk about the social and ecological problems in the context of real-world policy proposals is that she speaks of motion forward in a long struggle rather than pretending the Green New Deal is the solution for all our problems. On Fire makes it clear that there are no magic wands to wave, no magic bullets to fire.

The problem is that the Green New Deal does rely on one bit of magical thinking—the techno-optimism that emerges from the modern world’s underlying technological fundamentalism, defined as the faith that the use of evermore advanced technology is always a good thing. Extreme technological fundamentalists argue that any problems caused by the unintended consequences of such technology eventually can be remedied by more technology. (If anyone thinks this definition a caricature, read “An Ecomodernist Manifesto.”)

Klein does not advocate such fundamentalism, but that faith hides just below the surface of the Green New Deal, jumping out in “A Message from the Future with Alexandria Ocasio-Cortez,” which Klein champions in On Fire. Written by U.S. Rep. Ocasio-Cortez (the most prominent legislator advancing the Green New Deal) and Avi Lewis (Klein’s husband and collaborator), the seven-and-a-half minute video elegantly combines political analysis with engaging storytelling and beautiful visuals. But one sentence in that video reveals the fatal flaw of the analysis: “We knew that we needed to save the planet and that we had all the technology to do it [in 2019].”

First, talk of saving the planet is misguided. As many have pointed out in response to that rhetoric, the Earth will continue with or without humans. Charitably, we can interpret that phrase to mean, “reducing the damage that humans do to the ecosphere and creating a livable future for humans.” The problem is, we don’t have all technology to do that, and if we insist that better gadgets can accomplish that, we are guaranteed to fail.

Reasonable people can, and do, disagree about this claim. (For example, “The science is in,” proclaims the Nature Conservancy, and we can have a “future in which catastrophic climate change is kept at bay while we still power our developing world” and “feed 10 billion people.”) But even accepting overly optimistic assessments of renewable energy and energy-saving technologies, we have to face that we don’t have the means to maintain the lifestyle that “A Message from the Future” promises for the United States, let alone the entire world. The problem is not just that the concentration of wealth leads to so much wasteful consumption and wasted resources, but that the infrastructure of our world was built by the dense energy of fossil fuels that renewables cannot replace. Without that dense energy, a smaller human population is going to live in dramatically different fashion.

I don’t know what Klein actually thinks about this, but she does think drastic changes are coming, one way or another.  She writes:

Because while it is true that climate change is a crisis produced by an excess of greenhouse gases in the atmosphere, it is also, in a more profound sense, a crisis produced by an extractive mind-set, by a way of viewing both the natural world and the majority of its inhabitants as resources to use up and then discard. I call it the “gig and dig” economy and firmly believe that we will not emerge from this crisis without a shift in worldview at every level, a transformation to an ethos of care and repair.

Jensen adds:

The domination/subordination dynamic that creates so much suffering within the human family also defines the modern world’s destructive relationship to the larger living world. Throughout the book, Klein presses the importance of telling a new story about all those relationships. Scientific data and policy proposals matter, but they don’t get us far without a story for people to embrace. Klein is right, and On Fire helps us imagine a new story for a human future.

I offer a friendly amendment to the story she is constructing: Our challenge is to highlight not only what we can but also what we cannot accomplish, to build our moral capacity to face a frightening future but continue to fight for what can be achieved, even when we know that won’t be enough.

One story I would tell is of the growing gatherings of people, admittedly small in number today, who take comfort in saying forthrightly what they believe, no matter how painful—people who do not want to suppress their grief, yet do not let their grief overwhelm them.


UN Climate Action Summit

4 September, 2019

Christian Williams

Hello, I’m Christian Williams. I study category theory with John Baez at UC Riverside. I’ve written two posts on Azimuth about promising distributed computing endeavors. I believe in the power of applied theory – that’s why I left my life in Texas just to work with John. But lately I’ve begun to wonder if these great ideas will help the world quickly enough.

I want to discuss the big picture, and John has kindly granted me this platform with such a diverse, intelligent, and caring audience. This will be a learning process. All thoughts are welcome. Thanks for reading.

(Greta Thunberg, coming to help us wake up.)

I am the master of my fate,
      I am the captain of my soul.

It’s important to be positive. Humanity now has a global organization called the United Nations. Just a few years ago, members signed an amazing treaty called The Paris Agreement. The parties and signatories:

… basically everyone.

By ratifying this document, the nations of the world agreed to act to keep global warming below 2C above pre-industrial levels – an unparalleled environmental consensus. (On Azimuth, in 2015.) It’s not mandatory, and to me that’s not the point. Together we formally recognize the crisis and express the intent to turn it around.

Except… we really don’t have much time.

We are consistently finding that the ecological crisis is of a greater magnitude and urgency than we thought. The report that finally slapped me awake is the IPCC 2018, which explains the difference between 2C and 1.5C in terms of total devastation and lives, and states definitively:

We must reduce global carbon emissions by 45% by 2030, and by 100% by 2050 to keep within 1.5C. We must have strong negative emissions into the next century. We must go well beyond our agreement, now.

(Blue is essentially, “we might still have a stable society”.)

So… how is our progress on the agreement? That is complicated, and a whole analysis is yet to be done. Here is the UN progress tracker. Here is an NRDC summary. Some countries are taking significant action, but most are not yet doing enough. Let that sink in.

However, the picture is much deeper than only national. Reform sparks at all levels of society: a US politician wanting to leave the agreement emboldened us to form the vast coalition We Are Still In. There are many initiatives like this, hundreds of millions of people rising to the challenge. A small selection:

City and State Levels
Mayors National Climate Action Agenda, U.S. Climate Alliance
Covenant of Mayors for Climate & Energy
International Levels
Reducing emissions from deforestation and forest degradation (REDD)

RE100, Under2 Coalition (The Climate Group)
Everyone Levels
Fridays for Future, Sunrise Movement, Extinction Rebellion, Climate Reality

Each of us must face this challenge, in their own way.


Responding to the findings of the IPCC, the UN is meeting in New York on September 23, with even higher ambitions and higher stakes: UN Climate Action Summit 2019. The leaders will not sit around and give pep talks. They are developing plans which will describe how to transform society.

On the national level, we must make concrete, compulsory commitments. If they do not soon then we must demand louder, or take their place. The same week as the summit, there will be a global climate strike. It is crucial that all generations join the youth in these demonstrations.

We must change how the world works. We have reached global awareness, and we have reached an ethical imperative.

Please listen to an inspiring activist share her lucid thoughts.

Civilizational Collapse (Part 4)

26 August, 2019

This is part 4 of an intermittent yet always enjoyable series:

Part 1: the rise of the ancient Puebloan civilization in the American Southwest from 10,000 BC to 750 AD.

Part 2: the rise and collapse of the ancient Puebloan civilization from 750 AD to 1350 AD.

Part 3: a simplified model of civilizational collapse.

This time let’s look at the collapse of Greek science and resulting loss of knowledge!

The Antikythera mechanism, found undersea in the Mediterranean, dates to somewhere between 200 and 60 BC. It’s a full-fledged analogue computer! It had at least 30 gears and could predict eclipses, even modelling changes in the Moon’s speed as it orbits the Earth.

What Greek knowledge was lost during the Roman takeover? We’ll never really know.

They killed Archimedes and plundered Syracuse in 212 BC. Ptolemy the Fat—”Physcon” —put an end to science in Alexandria in 154 BC with brutal persecutions.

Contrary to myth, Library of Alexandria was not destroyed once and for all in a single huge fire. The sixth head librarian, Aristarchus of Samothrace, fled when Physcon took over. The library was indeed set on fire in the civil war of 48 BC. But it seems to have lasted until 260 AD, when it basically lost its funding.

When the Romans took over, they dumbed things down. In his marvelous book The Forgotten Revolution, quoted below, Lucio Russo explains the evil effects.

Another example: we have the first four books by Apollonius on conic sections—the more elementary ones—but the other three have been lost.

Archimedes figured out the volume and surface area of a sphere, and the area under a parabola, in a letter to Eratosthenes. He used modern ideas like ‘infinitesimals’! The letter was repeatedly copied and made its way into a 10th-century Byzantine parchment manuscript. But this parchment was written over by Christian monks in the 13th century, and only rediscovered in 1906.

There’s no way to tell how much has been permanently lost. So we’ll never know the full heights of Greek science and mathematics. If we hadn’t found one example of an analogue computer in a shipwreck in 1902, we wouldn’t have guessed they could make those!

And we shouldn’t count on our current knowledge lasting forever, either.

Here are some more things to read. Most of all I recommend this book:

• Lucio Rosso, The Forgotten Revolution: How Science Was Born In 300 BC And Why It Had To Be Reborn, Springer, Berlin, 2013. (First chapter.)

Check out the review by Sandro Graffi (who taught me analysis when I was an undergrad at Princeton):

• Sandro Graffi, La Rivoluzione Dimenticata (The Forgotten Revolution), AMS Notices (May 1998), 601–605.

Only in 1998 did scholars get serious about recovering information from the Archimedes palimpsest using ultraviolet, infrared and other imaging techniques! You can now access it online:

The Archimedes Palimpsest Project.

Here’s a good book on the rediscovery and deciphering of the Archimedes palimpsest, and its mathematical meaning:

• Reviel Netz and William Noel, The Archimedes Codex: Revealing the
Secrets of the World’s Greatest Palimpsest
, Hachette, UK, 2011.

Here’s a video:

• William Noel, Revealing the lost codex of Archimedes, TED, May 29, 2012.

Here are 9 videos on recreating the Antikythera mechanism:

Machining the Antikythera mechanism, Clickspring.

The Wikipedia articles are good too:

• Wikipedia, Antikythera mechanism.

• Wikipedia, Archimedes palimpsest.

• Wikipedia, Library of Alexandria.

The Mathematics of the 21st Century

13 January, 2019


Check out the video of my talk, the first in the Applied Category Theory Seminar here at U. C. Riverside. It was nicely edited by Paola Fernandez and uploaded by Joe Moeller.

Abstract. The global warming crisis is part of a bigger transformation in which humanity realizes that the Earth is a finite system and that our population, energy usage, and the like cannot continue to grow exponentially. If civilization survives this transformation, it will affect mathematics—and be affected by it—just as dramatically as the agricultural revolution or industrial revolution. We should get ready!

The slides are rather hard to see in the video, but you can read them here while you watch the talk. Click on links in green for more information!