Under the Partial Test Ban Treaty (PTBT), all nuclear tests except for those underground are banned. Under the Non-Proliferation Treaty (NPT), only the permanent members of the UN Security Council are legally allowed to possess nuclear weapons. Given the public outcry over fallout that led to the PTBT and the worries over widespread nuclear proliferation that led to the NPT, it’s clear that we require something beyond pinky promises to verify that countries are meeting the terms of these treaties.

But how do we do so? How can you tell when a country tests an atomic bomb? How can you tell who did it? And how can one differentiate a bomb on the surface from a bomb in the atmosphere from a bomb in space from a bomb underwater from a bomb underground?

I’m going to focus on two efforts to monitor nuclear weapons: the national security apparatus...

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[10 minute read]

Last week, I used the Graph Model of Conflict Resolution to find a set of stable equilibria in the present conflict between North Korea and the USA. They were:

• The tense status quo (s. 0)
• An American troop withdrawal, paired with North Korea giving up its nuclear weapons (s.10)
• All out conventional warfare on the Korean Peninsula (s. 4)
• All out nuclear warfare on the Korean Peninsula (s. 5)

But how much can we trust these results? How much to they depend on my subjective ranking of the belligerent’s preferences? How much do they depend on the stability metrics I used?

To get a sense of this, I’m going to add another stability metric into the mix, come up with three new preference vectors, and look at how the original results change when we consider a North Korean invasion to...

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[10 minute read]

Why do things happen the way they do?

Every day, there are conflicts between decision makers. These occur on the international scale (think the Cuban Missile Crisis), the provincial level (Ontario’s sex-ed curriculum anyone?) and the local level (Toronto’s bike lane kerfuffle). Conflict is inevitable. Understanding it, regrettably, is not.

The final results of many conflicts can look baffling from the outside. Why did the Soviet Union retreat in the Cuban missile crisis? Why do some laws pass and others die on the table?

The most powerful tool I have for understanding the ebb and flow of conflict is the Graph Model of Conflict Resolution (GMCR). I had the immense pleasure of learning about it under the tutelage of Professor Keith Hipel, one of its creators. Over the next few weeks, I’d like to share it with you.

GMCR is done...

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[10 minute read]

The following is the annotated speakers notes for a talk I gave on nuclear weapons today. I’d like to claim that it was a transcript, but after practicing from these notes for almost a week, I ended up giving the talk mostly ex tempore. Like I always do. 

Note: The uncredited photos were created by the US government and therefore have no copyright attached. All other images are either original (and therefore covered by the same license as the rest of the blog) or are credited and subject to the original license (normally CC-BY of some sort).

Hi I’m Zach.

This will be a backwards explanation of nuclear weapons; I don’t have time to cover it all so instead of covering the boring stuff like how fission works, I’m going to talk about the strategic...

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“We knew the world would not be the same. A few people laughed, a few people cried, most people were silent. I remembered the line from the Hindu scripture, the Bhagavad-Gita… ‘Now, I am become Death, the destroyer of worlds.’” – J Robert Oppenheimer, on the reaction to the successful test of the first atomic bomb.

[30 minute read]

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I recently read The Singularity is Near as part of a book club and figured a few other people might benefit from hearing what I got out of it.

First – it was a useful book. I shed a lot of my skepticism of the singularity as I read it. My mindset has shifted from “a lot of this seems impossible” to “some of this seems impossible, but a lot of it is just incredibly hard engineering”. But that’s because I stuck with it – something that probably wouldn’t have happened without the structure of a book club.

I’m not sure Kurzweil is actually the right author for this message. Accelerando (by Charles Stross) covered much of the same material as Singularity, while being incredibly engaging. Kurzweil’s writing is technically fine – he can string a sentence together and he’s clear – but incredibly repetitious. If you read the introduction,...

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In an effort to make my nuclear weapons post series a one stop resource for anyone interested in getting up to speed on nuclear weapons, I’ve decided to add supplementary materials filling any gaps that are pointed out to me. This supplementary post is on laser enrichment.

Enrichment is one of the more difficult steps in the building of certain nuclear weapons. Currently, enrichment is accomplished through banks of hundreds or thousands of centrifuges, feeding their products forward towards higher and higher enrichment percentages.

Significant centrifuge plants are relatively big (the Natanz plant in Iran covers 100,000m², for example) and require a large and consistent supply of energy, which often makes it possible spot them in satellite imagery. The centrifuges themselves require a recognizable combination of components, which are carefully monitored. If a nation were to suddenly buy up components implicated in centrifuge design, it would clearly signal...

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Nuclear weapons represent an existential risk. I’ll let 80,000 Hours speak for me for a minute:

A survey of academics at the Global Catastrophic Risk Conference by Oxford University estimated a 1% chance of human extinction from nuclear wars over the 21st Century. … Luke Oman estimates the probability “for the global human population of zero resulting from the 150 Tg of black carbon scenario in our 2007 paper [delving into the effects of a single nuclear exchange] would be in the range of 1 in 10,000 to 1 in 100,000.” This being said, we think this estimate is too low, as it doesn’t account for the potential for weaknesses in their model or the risk of a societal collapse causing a permanent reduction in humanity’s ability to reach its potential (which is nonetheless an existential risk even if people remain).

If you’re interested in reducing the existential risk...

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Having covered the practicalities of nuclear physics, nuclear weapon design, and nuclear weapon effects, we may now turn our attention to the strategies that have grown out of these physical realities.

7.1 Tactical and Strategic Weapons

Broadly speaking, there are two kinds of nuclear weapons – tactical and strategic. This post has been focused primarily on strategic nuclear weapons, high yield weapons capable of destroying cities and hardened targets. Tactical nuclear weapons have smaller yields, allowing them to be hypothetically used on a battlefield that contains friendlies.

The line between the two gets somewhat blurred with the highest yield tactical weapons. Is a 5kt bomb tactical or strategic? No one really has a clear answer. These already crystal clear waters get muddied further when you add in “dial-a-yield” weapons, which can yield anywhere from <1kt to ~100kt. On the low end, they’re definitely tactical. But at the high end,...

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All the nukes in the world are useless unless you have a way to get them to their targets. Aside from outlandish and potentially suicidal methods like suitcase nukes or nuclear artillery, there are three main ways of doing this: bombers, intercontinental ballistic missiles (ICBMs), and submarine launched ballistic missiles (SLBMs).

6.1 Bombers

The only nuclear weapons ever used in anger were delivered by B-29 bombers, the Enola Gay and the Bockscar. Because the Allies had attained near total air-superiority over Japan at the time of the bombings, it was possible for these bombers to go in without any real escort. They were accompanied only by weather reconnaissance and observation planes.

In a modern nuclear exchange, total air superiority would probably be required for a country to be able to openly deliver a bomb. If a nuclear bombing is attempted with anything less than total superiority, the attacker can...

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To understand the effects of nuclear weapons, you first need to understand how those effects scale with weapon yield.

5.1 Scaling

Modern bombs are much smaller than the Tsar Bomba. The standard US nuclear warhead, the W88, is a “mere” 475kt, a yield that is 100x less than that of the Tsar Bomba. On the other hand, the W88 weighs in at 360kg, 75x lighter.

This may seem like a poor trade, but it’s actually a very good one, due to the fundamental properties of explosive scaling. Scaling factors are very important to weapons. They determine the stable equilibriums that designs fall into. For example: we have tanks instead of mechs because strength scaling and mass scaling together make tall vehicles very vulnerable to weapons.

Scaling factors for all nuclear weapon effects (the fireball, the shock wave, and electromagnetic radiation) are different, but we can use the scaling factor...

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The last section required that you take it on faith that nuclear weapons are hard to design. Now it’s time to get into the nitty-gritty details of weapon design and understand why that is.

Nuclear explosions require a critical mass of the right unstable isotope. But there’s no safe way to store an assembled critical mass. As soon as you get to the critical mass, the chain reaction starts and an explosion will occur without drastic countermeasures.

All nuclear weapon design ultimately starts with this problem of assembling a critical mass in situ (and only ever in situ).

The first atomic bombs used one of two methods: gun assembly or implosion. These methods are still used to this day in fission weapons or in the fission first stage of multiple stage weapons.

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There are currently nine countries with acknowledged or suspected nuclear arsenals. Five of them are signatories of the Non-Proliferation Treaty (NPT), the main international treaty aimed at minimizing the number of nuclear armed states. Ideally, no country or group would have nuclear weapons. Unfortunately, we don’t live in an ideal world; the NPT is maybe the next best thing.

The NPT acknowledges the right of the permeant UN Security Council members (UK, USA, France, China, and Russia) to possess nuclear weapons even as it bans anyone else from getting (or trying to get) them. The remainder of the nuclear armed states (Israel, Pakistan, India, and North Korea) haven’t signed on to NPT or signed and later withdrew from it. South Sudan also isn’t a signatory of the NPT – I think they just haven’t gotten around to it – but no one is particularly worried about that (for reasons that...

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For this to all make sense, we should start with a brief review of atomic theory.

All matter is made up of atoms. Atoms have an outer shell of negatively charged electrons (more accurate descriptions exist, but I’m not going to delve into them; throughout this section I’m going to use simplified models wherever they’ll do the topic justice) and an inner core containing uncharged neutrons and positively charged protons.

The number of protons in an atom determines which element the atom is. All atoms with two protons are helium, all atoms with six protons are carbon, and so on. Much of the time, elements will have the same number of electrons as they have protons, so that the charges cancel each other out. Forms of elements with differing numbers of electrons are called ions. Ionization is a very common phenomenon. You observe it whenever you see lightning or dissolve...

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With President Trump in possession of the nuclear launch codes, I have a feeling that many people who’ve neglected nuclear weapons as an important cause area may begin to sit up and take notice. This is a good thing. There currently exist basically no checks and balances on a US President’s ability to go to nuclear war. Harold Hering was cashiered from the Air Force in 1973 after asking (on the subject of nuclear weapons launch) “How can I know that an order I receive to launch my missiles came from a sane president?”. Nothing has changed since then.

This post series is meant as a non-exhaustive primer on the (declassified) physical and strategic realities of nuclear weapons. It’s supposed to get you up to the point where you can begin asking the right questions in a relatively short time period. If you want more information, I’ve included relevant...

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