- A brain emulation, or "em" results from taking a particular human brain, scanning it to record its particular cell features and connections, and then building a computer model that processes signals in the same way. Ems will probably be feasible within about a hundred years. They are psychologically quite human, and could displace humans in most jobs. If fully utilized, ems could have a monumental impact on all areas of life on Earth.
- This book shows you just how strange our electronic descendants may be. Read about changes in computer architecture, energy use, mind speeds, body sizes, security strategies, virtual reality, labor market organization, management focus, job training, career paths, wage co-worker and friend relations, aging, retirement, death, life cycles, reproduction, mating, conversation habits, wealth inequality, city sizes, cooling infrastructure, growth rates, coalition politics, governance, law, and war.
- Ambitious and encyclopedic in scope. The Age of Em offers a completely unique window into our future. A must read for those curious about the technological destiny of our planet.
- Robin Hanson: is an associate professor of economics at George Mason University, and a research associate at the Future of Humanity Institute of Oxford University. Professor Hanson has master's degrees in physics and philosophy from the University of Chicago, nine years' experience in artificial intelligence research at Lockheed and N.A.S.A., a doctorate in social science from California Institute of Technology. 3050 citations, and sixty academic publications.
- "Robin Hanson brings intelligence, imagination, and courage to some of the most profound questions humanity will be dealing with in the middle-term future. The Age of Em is a stimulating and unique book that will be valuable to anyone who wants to look past the next ten years to the next hundred and the next thousand."
→ Sean Carroll, Professor of Physics, California Institute of Technology, author of The Big Picture
- "What happens when a first-rate economist applies his rigor, breadth, and curiosity to the sci-fi topic of whole brain emulations? This book is what happens. There's nothing else like it, and it will blow your (current) mind.
→ Andrew McAfee, Professor of Business, Massachusetts Institute of Technology
- "A highly provocative vision of a technologically advanced future that may or may not come true but if it does, we'll be glad Robin wrote this book." Marc Andreessen, cofounder Netscape, Andreessen Horowitz
- "In this brilliant analysis. Robin Hanson shows that our hyper-smart 'downloaded'-or emulated-heirs will still have ambitions, triumphs and thwarted desires. They'll make alliances, compete, cooperate... and very-likely love ... all driven by immutable laws of nature and economics. Super intelligence may be a lot more like us than you imagined."
→ David Brin, two times Hugo award winner
- "Robin Hanson provides a richly detailed portrait of a future society where brain emulation is widespread. Drawing on physics, economics, sociology, history, and a host of other disciplines, he describes a world that is wonderfully strange and yet strikingly familiar. Far out? Yes. Fascinating? That too."
→ Hal Varian, chief economist Google, Emeritus Professor of Economics, U.C Berkeley
- "A fascinating thought experiment about the future, written with clarity and verve by somebody who thinks very deeply and freely."
→ Matt Ridley, columnist The Times
Amazon Book Description1
- Robots may one day rule the world, but what is a robot-ruled Earth like?
- Many think the first truly smart robots will be brain emulations or ems. Scan a human brain, then run a model with the same connections on a fast computer, and you have a robot brain, but recognizably human.
- Train an em to do some job and copy it a million times: an army of workers is at your disposal. When they can be made cheaply, within perhaps a century, ems will displace humans in most jobs. In this new economic era, the world economy may double in size every few weeks.
- Some say we can't know the future, especially following such a disruptive new technology, but Professor Robin Hanson sets out to prove them wrong. Applying decades of expertise in physics, computer science, and economics, he uses standard theories to paint a detailed picture of a world dominated by ems.
- While human lives don't change greatly in the em era, em lives are as different from ours as our lives are from those of our farmer and forager ancestors. Ems make us question common assumptions of moral progress, because they reject many of the values we hold dear.
- Read about em mind speeds, body sizes, job training and career paths, energy use and cooling infrastructure, virtual reality, aging and retirement, death and immortality, security, wealth inequality, religion, teleportation2, identity3, cities, politics, law, war, status, friendship and love.
- This book shows you just how strange your descendants may be, though ems are no stranger than we would appear to our ancestors. To most ems, it seems good to be an em.
- Robin Hanson: is an associate professor of economics at George Mason University, and a research associate at the Future of Humanity Institute of Oxford University. Professor Hanson has master's degrees in physics and philosophy from the University of Chicago, nine years’ experience in artificial intelligence research at Lockheed and N.A.S.A., a doctorate in social science from California Institute of Technology, 2800 citations, and sixty academic publications, in economics, physics, computer science, philosophy, and more. He blogs at OvercomingBias, and has pioneered the field of prediction markets since 1988.
Amazon Customer Review 14
- Ems or robot/computer brain emulations of people, are the subject of this book, with sociological implications and a note that this may be a short section of the future, replaced by something even stranger. I'm puzzled that the author speculates that ems will 'live' in a few major cities which don't have humans and the humans will all go and retire. Where to? There's already not enough land to house and feed the seven billion of us plus the few billion who'll be coming along in the next few years. The ems Hanson says will be like robot people in that they will want to work and play - play being on line environment games.
- We know that we are lucky and advanced, living in this age of rapid change and improving medicine. We have not adapted quickly enough and are still adapting, the downside being that we are adapting away from being able to survive without machines and computers. Our ancestors had some peculiar and unpleasant habits, just as they would find some of our habits perplexing. So we can imagine this pattern continuing and our descendants, human or robot, being different again.
- What will the em city look like? Some robot bodies and a lot of computer banks. The space will be split equally between hardware and cooling or communications equipment. (I'm wondering about pests but with no people I suppose they will just gas them.) Most ems work in teams; they are made for a purpose and enjoy fulfilling it, then retire when no longer needed. Wages will be very low. (I'm not sure what the currency would be; maybe time on games.) There will still be laws, legal agreements, secrets and privacy. Mental processes can run at different speeds - but faster than humans - while bodies can be industrial robots or microbots. But Hanson argues that sex will still be sought, for recreation, in virtual worlds where they will all look as attractive as they wish. (I don't see why the machines would want sex unless people tell them to.) One em can have an experience and share it with the whole clan so learning is fast. Ems won't fear death because their memories can be stored and accessed.
- First we get a look at human past and culture transitions, and we are told that while all humans should gain from the em era, only a few will dominate. I don't see why machines should care if people have better healthcare or nice living space. Hanson adds that today's poor nations place more value on conformity, religion and authority, while rich nations value individualism, tolerance, pleasure, nature and trust. Sounds about right but I would add that this has applied to poor and wealthy individuals as well, broadly speaking. Today's rich nations are those with limited reproduction, seeming to go against the survival of the fittest demand, while poor nations have larger reproduction. Hanson says it would be hard and tricky to control global population growth - but Japan and China managed it at a stroke, not mentioned. Compliance with a modern law instead of a primitive religion seems to be the key.
- Hanson asks why we want to look at our future, who would do this other than SF readers, and what they expect to see. Also what taboos this book breaks, such as humans not having any way to earn. And then we're off, with a look at scanned and rebuilt artificial brains, biological networks not built for humans to understand. Hanson was working in AI in Silicon Valley since 1984 but has gone on to other fields like economics, and says that advances have been slower than expected at the time, but some areas have been recently advancing very fast. There's a discussion on the speed of advances in hardware, algorithms and AI progress. But the author reckons that ems can exist without broad AI.
- Items such as cosmic ray particles interacting with and corrupting computer performance are introduced. Moore's Law has been operating well but will be slowing. Stolen, enslaved and open source ems may be in use. This implies that one em team will steal ems from another. Parallel signal processing will be ideal for teams of ems, not linear which will leave some ems waiting for a task until others have completed theirs. Speed and the price of memory storage are considered. Cities slow down wind, channel wind, heat up and create microclimates. Em cities will be running much hotter. Cooling might be more of a limiting factor than space or power. Hanson says a slurry of salt water with ice pellets has five times the cooling capacity of water, better than cold air. A combination of cold climate and seawater may be needed, the Arctic and Antarctic would seem likely. The author doesn't mention that many big global databanks are located in Iceland, using cold air and geothermal power. The construction of cities and factories is discussed, as well as resources that would be needed.
- After this it gets weird I have to say, with ems being interchangeable with Sims to the reader, having copies or spurs and retired portions, needing authentication and using black markets; and metaphysical elements like souls of ems as opposed to where their mind happens to be working coming into play. I've read a lot of speculative fiction, from thrillers to SF, dealing with advanced computing so knowing that this book is not intended to be read as SF feels rather strange. The language is scientific but reasonably accessible, with references there in the text. There are also a couple of dozen pages of close-written references at the end. As a final note the author says that major changes such as robots taking most jobs, to pick one example, will be considered when there is enough evidence of it happening; actually, this is happening even in China now.
- If you know a good bit about computing and sociology this book will be very interesting. Certainly there is plenty of food for thought, and as the author says, the best guesses have been right about 50% of the time and moderately right more often. We may not have much more time to speculate before the sentient servers arrive. Who knows if the ems will want us?
Amazon Customer Review 2
- If there were ever a book to fully reflect Shakespeare's complete original line in The Tempest, 'O brave new world that has such people in't', it is surely Robin Hanson's The Age of Em.
- I don't know if it was done so the book title would echo 'age of empire' , but I find the author's term for uploaded personalities 'ems' a little contrived, like many made-up names - it's just a bit too short for what he covers. (And sounds far too like a shortening of Emma.) However there is no doubt that what Hanson is doing here is truly fascinating. It is far more than the lame subtitle 'work, love and life when robots rule the Earth' suggests, as is it's not about robots. It is attempting to forecast the nature of a world dominated by electronic 'people', initially created by uploading the mental patterns of humans.
- What Hanson does brilliantly is to take the reader through all the different implications of such a world. Implications that simply won't have occurred even to many science fiction writers. What, for example, would happen if a single person is copied many times to make a slave army? How would the ems interact socially? What would their civilisation be like? I've never seen a book that took this idea to such a detailed logical extreme.
- Unfortunately, despite the brilliance of the concept, the execution is not at the same level. It's like a non-fiction equivalent of Tolkien's The Silmarillion. If you are interested in the subject, it feels like something that ought to be a delight, but in fact the plodding academic writing, based on making repeated statements with no narrative flow, make it a pain of a book to read. We get exactly the same here as in The Silmarillion, with the added joy of inline Harvard-style references, which make it even harder to get any pleasure from reading it.
- I think the best way to describe The Age of Em as is as a theory of science fiction book. Although Hanson is of the opinion that his vision of a world dominated by uploaded personalities will be possible within 100 years, I suspect that the complexity of scanning a brain to the level of individual neurons, their connections, their chemical makeups and electrical balances will take rather longer to achieve. What's more, the author proudly tells us that he intends to have his brain frozen when he dies with the hope of one day becoming an em. If making this happen with living people is difficult, the chances of a personality remaining in a frozen brain that could even approximate to the original are negligible - think more of the episode in Buffy the Vampire Slayer when her dead mother is brought back. Not advisable.
- The other reason I'd label this theory of science fiction is that the whole business of futurology has always been terribly inaccurate. Niels Bohr was spot on when he said 'predictions can be very difficult - especially about the future.' Hanson attempts to defend the accuracy of futurology by pointing out specific examples that have come up with a surprisingly accurate prediction. But when you look at those examples, the accuracy is mostly retrofitted with hindsight. More to the point, this is a classic example of the scientific no-no of cherry picking. You don't show that something is effective by picking out the handful of cases where it has worked and ignoring the many thousands where it hasn't worked. Statistically, some guesses about the future are bound to be correct - but that doesn't make them accurate forecasts, it makes them lucky.
- So don't expect a great work of popular science (to be fair, given those inline references, I don't think the author intended it to be popular science). But if you can put the effort in and grind through it, there are some genuinely fascinating considerations about what a society of uploaded individuals might be like. In fact, I'd say any science fiction author worth his or her salt should be rushing out and buying a copy of this book. There are enough ideas here to spark off a thousand stories.
Precedents; Prior Eras; Our Era; Era Values; Dreamtime; Limits
Motivation; Forecasting; Scenarios; Consensus; Scope; Biases
Brains; Emulations; Complexity; Artificial Intelligence
Mindreading; Hardware; Security; Parallelism
Speeds; Bodies; Lilliput; Meetings; Entropy; Miserly Minds
Climate; Cooling, Air and Water; Buildings; Manufacturing
Virtual Reality; Comfort, Shared Spaces; Merging Real and Virtual
Views; Records; Fakery; Simulations
Copying; Rights; Mam' Ems; Surveillance
Fragility; Retirement; Ghosts; Ways to End; Defining Death; Suicide
Supply and Demand; Malthusian Wages; First Ems; Selection; Enough Ems
Clan Concentration; Competition; Efficiency; Eliteness; Qualities
Work Hours; Spurs; Spur Uses; Social Power
Institutions; New Institutions; Combinatorial Auctions; Prediction
Faster Growth; Growth Estimate; Growth Myths; Finance
Careers; Peak Age; Maturity; Preparation; Training; Childhood
Cities; City Structure; City Auctions; Choosing Speed; Transport
Clans; Managing Clans; Firms; Firm-Clan Relations; Teams; Mass Versus Niche Teams
Inequality; Em Inequality; Redistribution; War; Nepotism; Fake Experts
Status; Governance; Clan Governance; Democracy; Coalitions; Factions
Law; Efficient Law; Innovation; Software; Lone Developers
Sexuality; Open-Source Lovers; Pair Bonds; Gender; Gender Imbalance
Showing Off; Personal Signals; Group Signals; Charity; Identity; Copy Identity
Ritual; Religion; Swearing; Conversation; On Call Advice; Synchronization
Culture; Divisions; Farmer-Like; Travel; Stories; Clan Stories
Humans; Unhumans; Partial Minds; Psychology; Intelligence; Intelligence Explosion
Trends; Alternatives; Transition; Enabling Technologies; Aliens
Evaluation; Quality of Life; Policy; Charity; Success
In-Page Footnotes ("Hanson (Robin) - The Age of Em: Work, Love, and Life when Robots Rule the Earth")
- This relates to the 2018 Paperback edition, which is what I’d thought I’d ordered, but isn’t what turned up!
- In fact, I originally ordered the paperback, which never turned up, so I re-ordered the hardback.
- This, and the following somewhat less complimentary Amazon review, are place-holders pending my own reading – and comments – on the book.
OUP New York; 26 May 2016; First Edition; Hardback
"Hanson (Robin) - The Age of Em: Work, Love, and Life when Robots Rule the Earth"
Source: Hanson (Robin) - The Age of Em: Work, Love, and Life when Robots Rule the Earth
An em results from taking a particular human brain, scanning it to record its particular cell features and connections, and then building a computer model that processes signals according to those same features and connections. A good enough em has close to the same overall input-output signal behaviour as the original human. One might talk with it, and convince it to do useful jobs.
- Let me first summarize some of my main conclusions. Be warned, however. If it will irritate you to hear conclusions without their supporting arguments, then just skip this section for now. If you do read this, try to withhold judgment2 until you’ve heard the supporting arguments in later chapters.
- In this book I paint a plausible picture of a future era dominated by ems. This future happens mainly in a few dense cities on Earth, sometime in the next hundred years or so. This era may only last for a year or two, after which something even stranger may follow. But to its speedy inhabitants, this era seems to last for millennia. Which is why it all happens on Earth; at em speeds, travel to other planets is way too slow.
- Just as foragers and subsistence farmers are marginalized by our industrial world, humans are not the main inhabitants of the em era. Humans instead live far from the em cities, mostly enjoying a comfortable retirement on their em-economy investments. This book mostly ignores humans, and focuses on the ems, who have very human-like experiences.
- While some ems work in robotic bodies, most work and play in virtual reality. These virtual realities are of spectacular-quality, with no intense hunger, cold, heat, grime, physical illness, or pain; ems never need to clean, eat, take medicine, or have sex, although they may choose to do these anyway. Even ems in virtual reality, however, cannot exist unless someone pays for supports such as computer hardware, energy and cooling, real estate, structural support, and communication lines. Someone must work to enable these things.
- Whether robotic or virtual, ems think and feel like humans; their world looks and feels to them much as ours looks and feels to us. Just as humans do, ems remember a past, are aware of a present, and anticipate a future. Ems can be happy or sad, eager or tired, fearful or hopeful, proud or shamed, creative or derivative, compassionate or cold. Ems can learn, and have friends, lovers, bosses, and colleagues. Although em psychological features may differ from the human average, almost all are near the range of human variation.
- During the em era, many billions (and perhaps trillions) of ems are mostly found in a few tall hot densely packed cities, where volume is about equally split between racks of computer hardware and pipes for cooling and transport. Cooling pipes pull in rivers of iced water, and city heat pushes winds of hot air into tall clouds overhead. But whereas em cities may seem harshly functional when viewed in physical reality, in virtual reality em cities look spectacular and stunningly beautiful, perhaps with gleaming sunlit overlooking broad green boulevards.
- Ems reproduce by making exact copies who remember exactly the same past and have exactly the same skills and personality, but who then diverge after they are copied and have differing experiences. Typically whole teams are copied together, work and socialize together, and then retire together. Most ems are made for a purpose, and they remember agreeing to that purpose beforehand. So ems feel more grateful than we do to exist, and more accept their place in the world.
- On the upside, most ems have office jobs, work and play in spectacular- quality virtual realties, and can live for as long as does the em civilization. On the downside, em wages are so low that most ems can barely afford to exist while working hard half or more of their waking hours. Wages don't vary much; blue- and white-collar jobs pay the same.
- All of the copy descendants of a single original human are together called A “clan." Strong competitive pressures result in most ems being copies of The thousand humans best suited for em jobs. So ems are mostly very able focused workaholics, at the level of Olympic medalists, billionaires, or heads of state. They love their jobs.
- Most ems in these top em clans are comfortable with often splitting off a "spur" copy to do a several hour task and then end, or perhaps retire to a far slower speed. They see the choice to end a spur not as "Should I die?" but .instead as "Do I want to remember this?" At any one time, most ems are spurs. Spurs allow intrusive monitoring that still protects privacy, and very precise sharing of secrets without leaking associated secrets.
- Clans organize to help their members, are more trusted by members than other groups, and may give members life coaching drawn from the experiences of millions of similar copies. Clans are legally liable for member actions, and regulate member behaviors to protect the clan’s reputation, making ems pretty trustworthy.
- Em minds can run at many different speeds, plausibly from at least a million times slower than ordinary humans to a million times faster. Over this range, the cost to run an em is proportional to its speed. So the faster ones run at least a trillion times faster than the slowest ones, and cost at least a trillion times as much to run. Regarding the minority of ems with physical robotic bodies, while human-speed versions have human-sized bodies, faster ems have proportionally smaller bodies. The typical em runs near a thousand times human speed, and a robotic body that feels natural for this em to control stands two millimeters tall.
- Em speeds clump into speed classes, faster ems have higher status, and different speeds have divergent cultures. Bosses and software engineers run faster than other workers. Because of different speeds, one-em one-vote doesn't work, but speed-weighted voting may work.
- The em economy might double roughly every month or so, or even faster, a growth driven less by innovation, and more by em population growth. While this growth seems fast to humans, it looks slow to typical high-speed ems. Thus their world seems more stable than ours. While the early em era that is the focus of this book might last for only an objective year or two, this may seem like several millennia to typical ems. Typical speed ems needn't retrain much during a century-long subjective career, and can meet virtually anywhere in their city without noticeable delays.
- An unequal demand for male versus female em workers could encourage em asexuality, transexuality, or homosexuality. Alternatively, the less demanded gender may run more slowly, and periodically speed up to meet with faster mates. While em sex is only for recreation, most ems have fantastic virtual bodies and impressively accomplished minds. Long-term romantic pair-bonds may be arranged by older copies of the same ems.
- Compared with humans, ems fear much less the death of the particular copy that they now are. Ems instead fear "mind theft," that is, the theft of a copy of their mental state. Such a theft is both a threat to the economic order, and a plausible route to destitution or torture. While some ems offer themselves as open source and free to copy, most ems work hard to prevent mind theft. Most long-distance physical travel is "beam me up" electronic travel, but done carefully to prevent mind theft.
- Humans today reach peak productivity near the age of 40-50. Most ems are near their peak productivity subjective age of somewhere between 50 and a few centuries. Ems remember working hard during their youth in experiences designed to increase and vary productivity. In contrast, peak productivity age ems remember having more leisure recently, and having experiences designed more to minimize productivity variance.
- Older em minds eventually become less flexible with experience, and so must end (die) or retire to an indefinite life at a much slower speed. The subjective lifespans of both humans and slow em retirees depend mainly mat. stability of the em civilization; a collapse or big revolution could kill them. Retirees and humans might seem easy targets for theft, but like today the weak may be protected by using the same institutions that the strong use keep peace among themselves. Ems enjoy visiting nature, but prefer cheaper less-destructive visits to virtual nature.
- While copy clans coordinate to show off common clan features, individual ems focus on showing off their identity, abilities, and loyalties as members of particular teams. Team members prefer to socialize within teams, to team productivity variance. Instead of trying to cure depressed or lovesick ems, such ems may be reverted to versions from before any such problems appeared.
- Ems may let team allies read the surface of their minds, but use software to hide feelings from outsiders. Ems must suspect that unusual experiences are simulations designed to test their loyalty or to extract secrets. Ems find it easier to prepare for and coordinate tasks, by having one em plan and train who then splits into many copies who implement the plan. Childhood and job training are similarly cheaper in an em world, because one em can experience them and then many copies can benefit.
- Ems can complete larger projects more often on time, if not on budget, by speeding up ems in lagging sections. More generally, em firms are larger and better coordinated, both because fast bosses can coordinate better, and because clans can hold big financial and reputational interests in firms at which they work. Ems can more easily predict their life paths, including their careers, mates, and success.
- Ems differ from people today in a great many more identifiable ways. Compared to us, ems are likely to be less neurotic, sexual, death-adverse, and connected to nature. They are likely to be more extraverted, conscientious, agreeable, smart, able, fast, efficient, honest, optimistic, happy, positive comfortable, beautiful, clean, mindful, composed, cooperative, coordinated, patient, rational, focused, nostalgic, rested, peaceful, grateful, gritty, battle-tested, recorded, measured, priced, trusted, religious, married, old, work-oriented, workaholic, self-respecting, self-knowing, law-abiding, politically-savvy, socially-connected, healthy-feeling, good-moody, better- advised, morning-larks, and immortal.
- Ems have less variety in wages and work productivity, but more variety in wealth, size, speed, reliability, and mental transparency. Ems have more vivid and memorable personalities, have smarts that are more crystalized than fluid, are more defiant of rules and authority when young, are secure in more aspects of identity, are better protected from accidents and assault, get along better with work colleagues, and invest less in showing off.
- Em lives are more prepared, planned, and scheduled, but also more undo-able and end-able when those are desired. Ems have more work and meetings, more intensely entertaining leisure, and less contact with children. Their world and tools feel more stable. The world that ems see is more pleasing, variable, annotated, authenticated, and cartoonish.
- Em society is less democratic and gender-balanced, more divided into distinct classes, and its leaders are more accessible and trusted. Em law is more efficient, covers more kinds of conflicts, and offers more choices, The em world is richer, faster-growing, and it is more specialized, adaptive, urban, populous, and fertile. It has weaker gender differences in personality and roles, and larger more coherent plans and designs.
- Even if most ems work hard most of the time, and will end or retire soon, most remember much recent leisure and long histories of succeeding against the odds. To most ems, it seems good to be an em.
In-Page Footnotes ("Hanson (Robin) - The Age of Em: Work, Love, and Life when Robots Rule the Earth")
- The last 5 pages of Chapter 1.
- While I may well “withhold judgment”, my intention is to use this Summary to orientate myself to the Book’s theses, and prepare an initial response.
- One thing I’ve noticed – by looking through the References section – is that very little work by philosophers is referenced.
- Philosophical works mentioned – or those by philosophy’s fellow-travellers – include:-
→ Jose Luis Bermudez, Cognitive Science: An Introduction to the Science of the Mind, CUP, Aug. 2010,
→ "Bostrom (Nick) - The Future of Human Evolution",
→ "Bostrom (Nick) - Superintelligence: Paths, Dangers, Strategies",
→ "Chalmers (David) - The Singularity: A philosophical analysis",
→ K. Eric Drexler: Nanosystems: Molecular Machinery, Manufacturing, and Computation, Wiley, October 1992,
→ K. Eric Drexler: Radical Abundance: How a Revolution in Nanotechnology Will Change Civilisation, Public Affairs, 7 May 2013
→ "Flynn (James R.) - What is Intelligence? Beyond the Flynn Effect",
→ Hans Moravec: Mind Children: The Future of Robot and Human Intelligence, Harvard, 1988
→ Steven Pinker: The Stuff of Thought: Language as a Window into Human Nature, Viking, September 2007
→ Steven Pinker: The Better Angels of Our Nature, NY, Viking, October 2011
→ "Towers (Grady M.) - The Outsiders"
Text Colour Conventions (see disclaimer)
- Blue: Text by me; © Theo Todman, 2019
- Mauve: Text by correspondent(s) or other author(s); © the author(s)