2019 Week 39: Microwaves, Search, and Running.

Short version: I try and explain how microwaves work, I changed my search engine, and ran the Blenheim Palace half marathon.

Long version:

Microwave (ovens)

This week over a (reheated) dinner I tried to explain how microwave ovens work. It was a good reminder of the difficulties of discussing science; first in actually knowing the underlying science, then in communicating it to different people with different (unknown) levels of prior understanding. It was humbling to stumble between gaps in my understanding of a common household appliance and a failure to find the language to explain what I did understand. After refreshing myself on the physics, I try to explain again.

To start:
Microwave ovens convert electrical energy to heat, and are used for warming and cooking food. Other electrical cooking appliances (e.g. stoves, ovens, grills, toasters, and kettles) use the property that a flow of electricity heats the wire (conductor) it flows through. Microwaves make electromagnetic waves (like visible light or radio waves) in the microwave region of the spectrum (hence the name), which heat food (particularly water) as they pass through it. Conventional methods of heating food heat from the surface which gradually warms inwards, where as microwaves can heat food from the inside directly.

Assumed knowledge:
It is easy (and fun!) to get into a spiral of questions about what “heat”, “food”, “electricity” and “electromagnetic waves” are. More information about the parts of a system help build a foundation form where the combined system can be understood; it is hard to understand the science of cooking without understanding a little of the chemistry of what food is, or the physics of what heat is. Also seemingly unrelated knowledge can be useful; if how a musical instrument generates certain sounds is known, then the similar principles of resonant frequencies helps to explain how the microwaves are generated by the magnetron, another type of resonant cavity.

The best I can do:
Food goes in a metal box (a cavity) that stops microwaves escaping. Electricity (240 V AC mains) goes to a transformer that changes the voltage into two windings, a high voltage (approx 2000V) and a low voltage (approx 5 V). The lower voltage powers the user interface (e.g. the clock) and the higher voltage powers the microwave generator, called a magnetron. The magentron is a cylindrical vacuum cavity (closed metal tube with no air) where electrons are thrown off a central filament and travel to the outer walls. Strong magnets cause the electrons to travel along curved paths, and the cavity has spokes that extend from the outer walls most of the way towards the central filament. The spacing of these spokes and the strength of the magnets is tuned so that a specific frequency of electromagnetic radiation (microwaves) are generated by moving charger in the magentron, and these microwaves are guided by a metal tube (wave guide) into the larger cavity containing the food. The generated microwaves bounce around the cavity until they interact with water molecules (and sugars and some fats) in food to vibrate them. This is observed microscopically as heating.

A comprehensive explanation:
Can be found in this paper by Michael Vollmer. Also this video is a good guide.

Microwaves and super-res:
At the moment I work with super-resolution microscopes, which connects with microwave ovens in an interesting way: The grill that lets the user see their food being heated has holes (approx 1 mm across) that are much larger than the wavelength of visible light (approx 0.001 mm) but much smaller than the wavelength of the microwaves (approx 122 mm). Waves cannot “see” and object much smaller than the wavelength of the wave, called the “diffraction limit”. Thus the grill on the door of a microwave oven is “diffraction limited” from the perspective of the microwaves, in the same way that cellular structures can be “diffraction limited” from visible light. I am not sure if the equivalent optics exist for microwaves as in visible light, but it could be possible (though not particularly useful) to super-resolve structures using microwaves. Given microwaves are used in radar, perhaps such techniques are already used for detection of rain, birds, or aircraft.

Small Nudge to Search:

This week I changed my default search engine from google to google scholar.

This has had frustrating consequences; where as typically to find out where a place is, what tomorrow’s weather would be, or to play a song, I simply press the hot-key for a new browser tab and type what I want, that now gives me search results from the academic literature. There are no papers telling me if it will rain in Oxford tomorrow.

I do think this is a useful step. I’ve been reading a little about nudges, a concept linked to Richard Thaler. Changing the default search makes it slightly easier to do literature searches, and slightly harder to do general web searches, which I hope (and expect) will nudge me towards consuming better quality content.

Value-Action Gap

I came across the term “Value-action Gap“, which adds a technical but intuitive term where I would otherwise use the more judgemental “hypocrisy” or the more debater-jargon “principle consistency”. I like hearing opinions on why it is that people often act out of alignment with their beliefs, and am often surprised at my own capacity for cognitive dissonance.

Blenheim Palace Half Marathon

Slightly disappointed with my time, but it was a fun race. I will be adding a race report soon.

Photo from the Week:

2019 Week 38: Food Miles and Mental Health

Short version: I ate an apple, which got me thinking about climate change. I’ve also been talking about mental health. Purdue went bust. Not every article with 300 citations is novel.

Long version:

Climate Economics: Food Miles

I was eating an apple, here in Oxford, and discovered from the oft mocked apple sticker that it had been grown in an orchard in New Zealand (on the other side of the planet). This struck me as a problem; surely the fuel in transporting food around the world is an externality contributing to climate change. I wanted to know the specific quantity of fuel burned to make this possible, and found this study from New Zealand university Lincoln that claims there is a smaller climate impact from consuming New Zealand apples in the UK compared with local ones. I am sceptical, and will hope to follow up on this in a later post, but the data is summarised in table 7.3 on page 72. Summarising and converting the units to equivalent millilitres of Diesel burned we get:

Equivalent Fuel Burned
(diesel in mL) per apple (assume 100 g) for
NZ ApplesUK Apples
Direct energy consumption at orchard15.679.4
“Chemicals” e.g. fertiliser pesticides12.917.6
Shipping (NZ) and “Cold storage” (UK)65.244.8

So New Zealand is much more efficient at producing apples (about 5x less energy per apple is needed at the orchard), which largely corresponds to better yield per area of land (at 50 tonnes vs 14 tonnes of produce per hectare in New Zealand and the UK respectively), but also is due to better use of renewable electricity generation in NZ (particularly hydroelectric, wiki links to UK and NZ). This energy difference is almost entirely closed by the fuel used in shipping, but the use of “cold storage” of apples in the UK emits a further 44.8 mL equivalent diesel burned.

In short, the study suggests that fresh apples in the UK cause the same emissions per apple as New Zealand apples shipped to the UK, but if the apples are kept in refrigerated storage then the UK apples have a worse impact on the climate.

One notable thing from this exercise is that when you buy a 20p apple at Tesco, you are also paying for about 15p of diesel that was burned to get it from the tree to you.

Climate Change

This week’s Economist cover is a graphic that describes the warming climate. Meanwhile this photo article from the Guardian (also this week) hit me emotionally. The climate is changing, and the effects are disturbing. Currently my approach is very ivory tower: observing and considering, but not actively campaigning. I have friends who are much more active in Green Political Parties and movements like Extinction Rebellion. I think it may be time to explore similar options. I could blog each week about climate change in an attempt to raise awareness, but I would be very surprised if any of my readers were unaware of the issues?

Mental Health

Last week my friend Jessy shared some insight from her time answering a crisis hotline (read on facebook or linkedin). At work we now have staff trained in mental health first aid. It is good to see mental health issues lose their stigma, even if it is a gradual process. I thought someone might find things I do to maintain good mental health useful.

Mental Health Tool kit
(or “Things I do that I think help me mentally”)
Have a plan: Be enrolled in a health care program, have a GP, speak to them about mental health. Know services in your area. Have hotlines in your contact list. (If you broke your leg or developed an odd growth you would know what to do, what if you broke your mind or developed an odd pattern of thoughts?)
Reflect: Write things down to get them out of your head. Write a couple words about how you feel each day somewhere. Notice if something keeps coming back. Even just putting information somewhere else helps me relax that I won’t forget it, so I can let it go even briefly.
Exercise: Match the mental stress with physical stress, release endorphins. “Get out of your mind by getting into your body”. Do something that makes you sweat for 10 minutes. Endorphins make you feel better. Matching the physical stress to your mental stress helps align how you feel. If you are physically worn out, you will sleep.
Sleep: Get good sleep. Put distractions far away. Passing out from alcohol is not sleep.
Eat Clean: Sugary oily foods (fast foods) taste great but make you feel terrible. You also know that they are bad for you so you feel guilty. Eating well makes you feel better.
Control: Organise your room. Go somewhere you want to (ideally under your own power like walking or cycling). You have so much freedom and power. Remind yourself of this by using it.
Breathe: Slow your breathing. Count four on the way in, hold for four, count four on the way out, hold for four, repeat until you don’t remember how long you’ve been trying this.
Mindfulness: Take some time to practice mindfulness (this is a skill that I can’t explain in a couple sentences, but I’d recommend trying the free sessions on Headspace).
Unplug: Go offline. You don’t need technology to survive. Switch off. Leave smart devices behind. Even leave your watch behind to lose track of time. Just be.

Purdue Pharma

On Monday Purdue Pharma filed for bankruptcy. Opiates are incredibly useful and powerful drugs, but are also addictive. The US over prescribed them, peaking at 81.2 prescriptions per 100 persons in 2010-2012. Those prescriptions and subsequent addictions and addiction related deaths are linked to the marketing of OxyContin in many lawsuits against Purdue Pharma. For a humorous take on a dire situation, see John Oliver (April 2019).

Quirks of Academia

A high school student in Australia recently published in a mathematics journal, and it made the news. I have read some slightly bitter comments along the lines of “so what”. There is a lot of pressure inside academia to publish papers (a metric of performance) and seeing a relatively simple result gain media coverage can inspire envy.

Tumbling down the rabbit hole led me to this (now defunct) blog, poking fun at Mary M Tai’s paper and claim to have developed a new method for finding the area under curves. That method may actually be over 2000 years old. That paper has 363 citations today (another metric of academic performance). I found this funny.

Photo from the Week

Some late nights in the lab have let me share runs with the wildlife of Oxford.

2019 Week 23: Yams

Short version: Waitrose is getting rid of some of their packaging, but didn’t stock yams.

Long version:

British Supermarkets

The United Kingdom has a much more diverse supermarket landscape than the Australian duopoly I grew up with. The British landscape is tiered, with M&S and Waitrose as the expensive, Asda, Sainsbury’s and Tesco as the middle, and Aldi, Iceland, and Lidl as the cheaper options. In my shopping there is a noticeable contrast in the demographic of the customers at Waitrose compared with Aldi, both on Oxford’s Botley Road. I suspect this is a product of the price differences appealing to different socio-economic classes. The data, however, suggests the difference is small.

The photo from the week is of Waitrose’s “Unpacked” campaign around removing packaging from their stores. Reducing waste is commendable, and the campaign has been successful in encouraging me to purchase more items from Waitrose. However on visiting many of the independent grocery stores on Cowley Road I realised that “Unpacked” is actually the default way of selling goods, rather than an “innovation”.


I tried cooking yams this week, as part of a larger project to improve my cooking by working through a single cookbook (written by the team of the former London restaurant Food for Thought).

The first problem was that I didn’t actually know what a yam is. The wikipedia page offers a disambiguation. This raises the question as to why a tuber produced primarily in equatorial regions would be popular in the UK. The ready availability of carribean food in general (of which yams are a component) in the UK is partially due to the Windrush generation. Finally a pop culture note: Kendrick Lamar’s yams are “authenticity, sex, and drugs“.


This Friday was the Dragon Boat Festival ( 端午节 ). My quest for yams brought me to some Chinese supermarkets here in Oxford and the presence of banana leaf wrapped rice (粽子) reminded me of the traditional Chinese holiday, and the story of Qu Yuan (屈原).

Photo from the Week

2019 Week 17: Castles and Coffee

Short version: Wales has a lot of castles, and I rebuilt my coffee machine.

Long version:


The weekend hiking trip to Wales was bookended by visiting the UNESCO listed Caernarfon and Conwy Castles. I was reminded of a book I loved as a child; “Castle” by David Macaulay, which is unsurprising given the fictional castle depicted is modelled after Conwy. While to me castles are a setting for stories and an element in games, in reality they were imposing military installations. In particular given Oxford is currently home, it is disquieting to consider that Oxford (and Cambridge) were both teaching students while Conwy was being built as part of Edward Longshanks’ conquest of the Welsh.


I like coffee. I am lucky to have been given a La Pavoni Europiccola, from which (literally) pulling shots of espresso gives me satisfaction and caffeination. Having such a manual machine highlights the chromatographic aspects of the process of making one of the world’s most popular beverages, and gives plenty of opportunities to experiment with process. For more on coffee, CGP Grey provides some interesting coffee facts in his video.

Photos from the Week

2019 Week 10: Fitness in Science

Short version: I grew up thinking science-y people weren’t fit, but there is plenty of fitness in science, and scientific reasons to keep fit. I share some thoughts on anatomy, metrics, protein powder, and astronauts.

Long version:

Personal Observations

I remember thinking of exercise as inherently a waste of time; why would you ever want to run in circles and just end up at the same place? I’m sure this was in part informed by the media I consumed growing up; portraying the stereotypical nerd as being interested in mathematics, science, technology, along with a lack of physical fitness (also, in retrospect, portraying very fit people as not particularly bright). I identified with those archetypes and spurned exercise through much of school, as did many of my peers. It was later in life that I realised improving cardiovascular endurance was important to health. Starting to run I discovered the joy of Runner’s High. A competitive mindset and an internship in an anti-doping laboratory led me to build regular exercise into my routine, something I’ve enjoyed maintaining for the past few years.

Athletes’ Anatomy

Athletes setting world records are obviously different from the norm. Skill, dedication, talent, training, and genetics all contribute. I find conversations about athletes success tend to drift towards the genetic element, perhaps the intrigue is due to the allure of quantifying potential, or perhaps it provides a comforting fatalism for the undertrained. Most likely it is interesting simply because it is poorly understood compared with the simplicity of regular training or perceptible skill.

David Epstein gave a TED talk in 2014 where he shared a number of facts about the nature of athletes’ physicality. It particularly stood out to me that a transition in sport occurred (in parallel with the rise of broadcast media) from favouring a generalist body type of average proportions, to a plurality of extremes. One of the most memorable statistics is that Hicham El Guerrouj and Michael Phelps, who differ in height by 17 cm, have the same length legs (running advantages longer legs proportional to height, whereas swimming is the opposite). These characteristics are difficult to change: no amount of training will allow these two to exchange their body type. Training can however alter different aspects of the body to similar extremes.

Physiological adaptations from training can be as radical as the size difference between NBA basketball players and Olympic gymnasts. Specifically, athletes’ hearts really are significantly bigger than those of the untrained population (particularly endurance athletes). The body responds to stress, and the process of repeated exertion to influence adaptations that increase performance for a given activity is the basis of all training. When I worked in anti-doping an office legend described a cycling team that, in the days before blood doping was banned or effectively enforced, would need to sleep with heart rate monitors that would wake them if their heart rate got too low for fear of their hearts stopping altogether.

Marathon Times and Personal Metrics

I’m pretty motivated by quantifiable goals. Either arbitrary times (usually round numbers) or achieving a certain relative performance (e.g. placing in the top 1%). This paper examining marathon finishing times suggests I’m not alone. Times tend to bunch below “whole numbers” such as 3 hours and 4 hours, as well as smaller bunching observed across 5 minute increments, as people dig a little deeper to get below their goal times.

More statistics on half marathons and marathons. BAA Marathon and Half-Marathon results with the code shown. (I would like to be able to code informative charts like this.)

Protein Powder

The literature suggests that, when combined with training, protein supplementation increases gains in strength. I find that protein powder is a convenient way to add protein to my diet, particularly as a vegetarian. The NHS points out that the same benefits of protein powder can be achieved from other protein-rich foods, and that the lack of vitamins and nutrients of protein powder compare to a balanced meal make it a poor replacement for meals. It also recommends not exceeding intakes of 111 g per day for men or 90 g for women, which more or less concurs with the BMJ’s study suggesting the benefits of protein supplementation cease after 1.62 g/kg/day i.e. 120 g for a 75 kg person.

Importantly from an environmental perspective, looking at the World Resources Institute protein scorecard I wrote about in Week 4, dairy (from which whey protein is sourced) has the third highest impact, more than chicken and pork. Fortunately vegetable sources (i.e. pea protein) has a much lower footprint than conventional animal sources and pea protein is just as effective as whey protein in producing additional muscle growth.

That all said, there are good reasons to be skeptical of any benefit of supplementation at all beyond a healthy balanced diet. Trying to define a healthy balanced diet though could easily be several papers (or blog posts) by itself.

NASA Twin Study

I am eagerly awaiting the release of the integrated paper covering the NASA Twin Study. I suspect this will be the most intensive series of measurements made of any individual for some time. A brief summary by the Scientific American.

Photos from the Week: Solid water.

In the first photo, unusually clean ice traps dissolved gasses as they are forced out of solution. The second and third photos show Oxford’s spring weather variation.

2019 Week 7: Zero to One

Short version: I read Peter Thiel’s notes on startups, had a couple college formal dinners, cycled in the Cotswolds, and bought some protein powder.

Long version:

Zero to One

Peter Thiel is founder of PayPal, and an early investor in Facebook, which have made him a billionaire. In 2012 he taught a course about startups at Stanford, which via Blake Master’s notes became the book Zero to One.

I will update this post later with my thoughts on the book and other missing sections.

Photos from the Week

2019 Week 4: Vegetarian

Short version: Why I don’t eat meat, some things I’m reading at the moment, and three photos from my week.

Long version:

Eating Less Meat

Since having moved to the United Kingdom, I’ve been eating less meat. The strongest motivation comes from a desire to minimise carbon impact and waste. The change has been made easy by meat substitutes being widely available and cheap (and delicious).

Intuitively, in order for humans to gain nutrition from an animal, that animal needs to consume either other animals or plants first. Given these processes cannot be completely efficient, there is always a lower energy cost to the environment to eat lower on the food chain. The real effect of this is described in the chart below.

High Protein Diets:
The CSIRO published a book advocating a high protein diet. It generated some controversy in part due to being funded by the meat industry. It still seems a high protein diet is healthy, but there is evidence swapping animal protein for plant protein lowers mortality overall.

More reading:
Publications from Nature and World Resources Institute about the impact of meat on climate change, which include the infographic above. Also, from a moral point of view, Consider the Lobster.

Stuff I read this week

Relevantly, restaurant reviews from the blog Vegan Eats Oxford. The Graduate Outcomes Survey was released. Matt Levine continues to write humorously about finance. Hybrid Perovskite Semiconductors are cool.

Photos: Cakes, Climbing, and Snow

Writing from home.