omenti

2 december 1942 - a half watt

4:00 PM 2-Dec-1942

Compton: The Italian navigator has landed in the New World.

Conant: How were the natives?

Compton: Very friendly

 

Almost exactly 80 years ago the first human-made self sustaining nuclear reaction took place under the stands of a vacant football field at the University of Chicago.  It's a remarkable story and something of a race with Nazi Germany.  Fortunately so many competent physicists had fled Germany that the Nazi bomb project was a failure.  It turns out the wikipedia article on the subject is an accurate and readable summary of the dawn of the pre-manhattan project effort to get a handle on nuclear fission.  The piece  gets a bit technical here and there, but you can skip over those parts if you like.  I'll try and give a high level view of what a sustained reaction is without going into the quantum mechanics of the process.

__________

 

Nuclear fission is the process where the nucleus of an atom breaks apart into smaller pieces releasing energy (often quite a bit) in the process.  The nucleus of an atom is a tight cluster made up of positively charged protons and electrically neutral neutrons.

All of those positive changes packed together - you might ask why don't they fly apart? After all, electromagnetism causes like charges repel.  It turns out a very strong force, cleverly called the strong force, acts on neutrons and protons binding them together.  A difference between the two forces becomes important.  Electromagnetism is a long range force while the strong force only acts over short subatomic distances. To first order you can think of the strong force acting only between immediate neighbors while the electromagnetic force acts on all of the protons.

If the nucleus gets big enough the total repulsive electromagnetic force of all of the protons overcomes the closest-neighbor strong force and breaks the nucleus up in to smaller pieces releasing energy in the process (nuclear fission)

Most of the elements we're used to have nuclei that are too small to break up on their own.  A few are on the borderline. In the case of uranium the addition of a single neutron is enough to undergo fission and in the process it releases energy and, on average somewhat more than two extra neutrons along with a couple of nuclei that are smaller than uranium.¹

In nature uranium usually isn't concentrated and the neutrons from fission are absorbed by other materials.² But if you concentrate uranium you get to a point where each fission has a high probability of striking another uranium nucleus and so on - creating a sustained reaction. Unchecked, with enough purity, and you get an atomic bomb. At lower concentrations and with the ability control the amount of neutron absorption you get a controlled nuclear reactor that liberates a useful amount of energy.

 

A number of interesting characters were involved in these early experiments.  Enrico Fermi was the key player in the first sustained reaction.  Physics was getting specialized and he was probably the last physicist who was both a great theorist and experimentalist. 

__________

¹ I've left out a lot.  I haven't mentioned which isotope of uranium for example.  Also - you may have noticed that adding an extra neutron shouldn't increase the electromagnetic force as the neutron is neutral.  It turns out the uranium nuclei is so close to breaking up that the kinetic energy of the addition neutron adds just enough to break things up.  A nice example is adding a neutron to U-235.  One possible fission chain  n + U-235 → Rb-92 + Cs-140 + 3n + 200 MeV of energy. 

Also details of the strong force weren't known at the time..  A clear hypothesis didn't arrive until about 30 years later and deeper details of the mechanism took almost thirty more..

² A natural formations of uranium t pure enough to initiate sustained nuclear reactions was discovered in Gabon.  It operated for a few hundred thousand years producing less than a megawatt of power.  

 

 

preview season

As many of you know I like to celebrate major accomplishments of friends.  This time I'll offer previews from two good friends as well as another that could have an impact on education.

 

The first is  Juliette Powell's second book.  The A.I. Dilemma: 7 Principles for Responsible Technology is the working title and it's a further development of her dissertation at Columbia.  I've been fortunate enough to have read the nearly-final draft.  Well balanced and accessible to non-specialists, it's going to be an excellent resource for people trying to sort out promises and pitfalls that can impact much of the future.  One person who had an advance look will be using it as required reading for a college course.  Be on the lookout!

 

The second is from Sarah Pavan.  One of the best beach volleyball players in the world, she's also a clear and deep thinker.  As I've aged I've learned to learn from those outside my area.  She's  been a source of ideas. At the elite level women's beach volleyball is a mental game with communication being one of the defining aspects.  A few months ago her teammate of five years decided to quit the team.  Sarah was faced with finding someone with the necessary complementary skill set as well as the drive, passion, ability to communicate and chemistry.  Canada only has a few candidates, but Sarah found the right one in Sophie Bukovec.  I expect to see them developing as a team over the next year as they focus on the Paris Olympics in 2024.

 

 

And finally potential news from what I consider the most important college course in the country. Sense & Sensibility & Science is a course at Berkeley developed and taught by faculty from Physics, Philosophy, and Psychology departments.   Here's an overview:

 

This is a course on the ideas from science that are most widely useful for everyone. Many insights and conceptual tools from scientific thinking are of great utility for all kinds of reasoning, from reading the news critically to making decisions under conditions of uncertainty. The focus in this course is on the errors humans tend to make, and the approaches scientific methodology has developed (and continues to develop) to minimize those errors. The course includes a discussion of the nature of science, what makes science such an effective way of knowing, how both non-scientific thinking and scientific thinking can go awry, and how we can reason more clearly and successfully as individuals, as members of groups, and as citizens of a democracy.

Every day we make decisions that can and should be informed by science. We make decisions as individuals, as voters, and as members of our various communities. We make decisions as students and parents and policy makers. The problem is, we don’t do it so well—a fact sadly apparent in political debates. It’s easy to blame poor decision-making on the greed, irresponsibility, ignorance, or incompetence of other people. But the problem seems to be more basic than that. It seems we face a paradox. Living in a democracy means that everyone’s view counts the same as everyone else’s. But to make decisions informed by science, we often need to defer to those with relevant expertise. Therefore, we shouldn't rely on a democratic system to make the best decisions. Or should we? This basic tension between science and democratic decision-making serves as a unifying theme for Sense & Sensibility & Science (SSS), a course that aims to equip students with basic tools to be better thinkers. We will explore key aspects of scientific thinking that everyone should know, especially the many ways that we humans tend to fool ourselves, and how to avoid them—including how to differentiate signal from noise, evaluate causal claims, and avoid reasoning biases. We’ll then look at the best models for using science to guide decisions, since the rational and arational (e.g., values, fears, and goals) then have to be combined. We will explore these themes experientially, often with in-class activities and discussions, and we will culminate in two open-ended projects to design better methods of deliberation and decision making, first as groups, and then as individuals. Co-taught by faculty from Physics, Philosophy, and Psychology, S&S&S fosters intellectual advancement for interdisciplinary knowledge seekers.

 

Browse through the topics and resources section.  You'll get something reading the recommended materials and thinking about the topics.  It's one of the few places outside the community where I've seen scientific optimism discussed. A book is being developed aimed at college students, although it should be widely applicable.  There's a serious need to put together something like this at the high school level even though many states would probably label thinking about the process of science as 'woke'..

feel free to comment!

an almost lost word from the dictionary

Reading an obscure paper from the 1880s a word stopped me - apricity.  It seemed like I had come across it before and there were hints from the context, but it was time for the OED.¹  I pulled out the first volume of my old compact edition - the one with the magnifying glass - and found it.  An obscure word dating to 1623 meaning the warmth of the Sun in the Winter.

 

The warmth of a bright Sun in on a clear cold Winter day.  That's something that captures most of us know - the radiant heat of the Sun isn't isn't perturbed by the cold air and can be quite comfortable.  Then it hit me I heard the word in a John McPhee lecture in Princeton.² A few decades had passed since he wrote Coming into the Country, but it was about three Alaskas including a look at the Winter.  A perfect word for some of the days.

 

A day of apricity can make snow melt in subzero air temperatures on  Southern-facing roofs only to freeze into beautifully clear long icicles at the edge.  This type of ice formation is often free of bubbles producing beautifully clear ice.  If you have wide enough icicles you might try making an ice lens and starting a fire.

 

Such days are made for outdoor recreation if there isn't any wind.  Perhaps more importantly the basic principle - heat transfer by radiation - can keep heating expenses down.  Heating and moving air to fill rooms is enormously inefficient. If you aren't moving around much you might try a small radiant heater and point it at the area where you are. Heat what you need to heat with infrared light. Direct sunlight is the same...  sit in the Sun.  These measures, plus wearing warm indoor clothing and being somewhat active lets you get away with low thermostat settings.  And be on the lookout for aprocity as that can give a big psychological boost!

 

Another Winter word I like is tingilinde. It's a constructed word based on J.R.R. Tolkien's elfin language Quenya meaning the sparkle of the starlight reflecting on the snow on a dark moonless Winter night.  Such sights could be spectacular in Montana away from town when it was really cold and a bit of new snow had fallen as tiny ice crystals. Another great spot is Yellowstone .. super cold air forms the right kind of ice crystal snow near the hot springs and geysers.   Once it was magical - the cold starlight reflecting from millions of tiny diamonds along with the greens and reds of a bright aurora dancing overhead.   On such nights you don't notice that it's really cold.

__________

¹ The Compact Edition of the Oxford English Dictionary is the 1928 edition.  Devilishly small print that requires a magnifying glass, but the real OED and only about $80 (still a lot back then!) rather than the fortune the full dictionary went for.  There's a lovely bit of historical fiction on the dictionary and the people who made it happen:  The Dictionary of Lost Words by Pip Williams.  It's set in the time and place with many of the characters, but focuses on what was left out..  those who weren't white, male and of a certain class.  Recommended!

² McPhee is a great writer - a master of the creative non-fiction genre.   

 

 

 

a 'I really know better than to post this post...'

a minipost

About this time of year I get a request or two to talk to a high school junior or senior about colleges and majors.  I'll give reasons why I'm not the best the person to talk to, but if they persist I'll spend some time listening and talking.  Curiously there have been three so far this year and two suggested I post something.  Perhaps it can spark you into helping some students - many of you have much richer backgrounds.

 

A caveat is that I came from a position of privilege: white male, reasonably good at math, and from a period of time when great positive change seemed possible.  I didn't view college as training for work.  Somehow I knew what I was curious about from the age of twelve, so it was just following a calling.  I knew I could always get work with the friend of the family in back home who had a thriving HVAC and water softener company. This gave me the freedom to follow a somewhat different path than friends who were thinking about what happened after graduation.   This led to good and bad choices.  I double majored, but the fields were too close to each other and I ended up with a narrow undergrad education. Since then I study a few areas on my own, but I didn't take advantage of a broader education back then.  On a more positive note I got to know several professors as friends and mentors. That part was priceless.

 

° Ask yourself why you want to go to college?  What is your drive?  Many answers are correct, but you should know yours.

 

° A 'what color is your parachute-ish' question: are there any kinds of work you would do for nothing or even pay to do? 

 

° Where may or may not be important.  It's a plus in some fields to attend a famous college, but in many cases the quality of education can be as good at state schools - sometimes even better if you're good at making connections and really dive into the courses.  Famous professors often don't have the time to talk to undergrads. 

 

° Spend some time finding out which professors can teach.  

 

° Double major if you can, but in mostly unrelated areas.  Even if you're focused on employment afterwards - a good ROI on college - choose the second major in a field that you might find fascinating.  The humanities can give you great depth and are underrated for turning you into someone who can think differently down the road.  I've mentored students with a variety of double majors: CS-music, CS-art, physics-philosophy, math-paleontology for example. If you're doing a D-I sport, consider that a major by itself.  It can give a rich training that can serve you down the line too.  If not a double major, make sure your minor is very different from the major.

 

° A benefit of getting to know professors and show an interest is you might be able to get in on some of their projects.  This is often in the form of work-study, which can take a bite out of the debt down the road.  I was lucky enough to get in on a few great projects.  The most interesting seemed boring at first and didn't pay, but it was in an area I hadn't thought about and the professor was brilliant.  There was even an opportunity to have a tiny contribution to a bit of history and I still use some of the learnings. 

 

° Remind yourself that you learn best when it's play.  This won't happen all of the time - or even most of the time - but work on it. 

 

° Learn to witness the immediate world around you in some depth.  I recommend basic drawing and field drawing courses.  There are many other paths, but a bit of time focusing on understanding the natural world around you changes the way you think. 

 

That's pretty much it.  I mainly listen to them. Some of the items I've mentioned cause them to react and think about their own situation.  This year I recommended How to be Perfect by Michael Schur.  It's basically a Philosophy 101 short course done in a brilliantly entertaining manner - the way an engaged professor might go at it.  (If you're interested the audiobook is much better than the printed version as Schur has a stage background.) 

 

design for kids and community in japan

a minipost

 

About twenty years ago I was associated with a human computer interface department. A good deal of the work was associated with this nebulous concept of “community”. The term tends to be defined in the mind of the person talking about it .. like the word god. We had a list of about twenty words that needed rigorous contest when we publishing internally or externally .. community was everyone’s first choice for the list, That said most of us default to a warm and fuzzy concept. How people and neighborhoods should interact. The sort of thing Bob Kraut worries about. (to be fair he also thinks about communities like QAnon)

 

A recent 99% Invisible podcast focused on Japanese community of place design.. deign for the six year old Mixed use zoning, very narrow roads, a school house at the center and very independent kids. Some of us worry about urban and suburban design and traffic - how to you minimize the two or three ton vehicle carrying a driver and a bag of groceries? We often look to the Netherlands snd the Nordics for inspiration Indeed they’re excellent examples of moving from 1970s car-centric design to something better for cyclists and pedestrians. Japan offers a different path - one that seems unlikely in the US.

 

Here’s the a link to the audio, a transcript and a few videos

 

A comment .. most of us of a certain age grew up with kids walking and cycling everywhere - starting around six for walking and seven or eight for cycling. It was the only way a kid could deal with the scale of suburban design with fixed zoning and wide roads. That’s the environment the Dutch and Nordics started with rather than doubling down on complete car dependance.

 

clearing the air

a mini-post

A year ago I managed to help out getting a small grant from the state to build a number of Corsi-Rosenthal boxes with the help of two teachers (science and art) and about twenty high school kids.  It took a Saturday morning to build about eighty of the air cleaners.  All but two are still working and, even though the filters are visually ugly and dirty, they're working just as well.   I won't list all of the learnings - get in touch if you want to know more - but a big benefit besides cutting the viral load is dramatically cutting PM 2.5.  Kids and teachers report fewer allergy and allergy problems and toxic particulate from a nearby highway has been cut.  I suspect these would be great for fires and dusty areas (thinking Arizona and Salt Lake City).   In the past year more clever variants have appeared so check out YouTube if you're curious.  Oh - and filter prices drop if you buy 100 at a time:-)  The only downside was I never want to see duct tape again,

 

The motivation for the post was a fun discussion Andy Slavitt had with Richard Corsi and Jim Rosenthal on his In the Bubble Podcast.   Such a fantastic project for kids and adults!  (there are a number of commercials - Andy donates all profits to charities).

<br.

couplings and friction

a quick minipost

 

Beginning physics students learn about simple coupled systems.  Things like pendulums with a weak spring between them and the like.  Next you look at somewhat more complex systems like a group of pendulums.  Put them on a solid surface and start them in different oscillations and they do their pendulum thing unaffected by their neighbors.  Now add a little communication by putting them on a floor that can transmit a bit of vibration, something interesting happens.

 

The coupling of systems is common in nature covering a very wide range of complexity inducing our brain.  Many of these systems are mathematically fascinating.  Turn up the amount of coupling and they behave as you might expect - at least to a point.  Then, as the comments of the system impose themselves on each other,  there's a dramatic change.  Sometimes these are good from our point of view and sometimes they're disasters.  The point of inflection is often marked by a perturbation - lightning strikes, hurricanes, pandemics, big lies.   The couplings are too strong to allow for anything but a change to a new state.

 

One feature of our society is an increased coupling of systems.  Social media and other targeted messaging, GPS, the Internet of Things, globalization, just in time everything, religion, democracy....  More systems are being connected and the amount of communication is increasing at a terrific rate. These couplings are often introduced to decrease cost and the "friction" parts of the system have with each other.   Many are  too complex to understand well, but the basic math of over coupled systems is clear - these systems can be very unstable. 

 

Building alternate pathways and redundancy into these systems is an answer, but that costs money and clever design.  Another alternative is reducing the coupling of certain important subsystems.  It's something I find myself paying more careful attention to.  Highly coupled or low-friction systems are usually brittle at some point.  I dislike the term "black swan" as real black swans (the bird) are not uncommon in nature.  But we continue to build serious and increasingly effective black swam bait...

 

 

 

just two things..

minipost

Recently I gave a talk to an audience of non-scientists.  During the question and answer section some asked "what's something important you'd leave us with?"

 

Everything you see is in the past.  Light travels about a foot in a billionth of a second, so if you look at your feet, light takes five or six billionths of a second to make it to your eyes.  You see your feet five or six billionths of a second in the past.  The moon you see is one and a quarter seconds in the past, and the Sun about eight and a third minutes.   The Andromeda galaxy, the farthest you can see without aid, about two and a half million years in the past.

 

I was going to point out it's more complex as it takes a few tenths of a second for your brain to register the image and the whole notion of "present" is imprecise, but that would muddy things.

 

Next someone asked for another useful piece of energy.  

 

About a horsepower of solar energy falls on an average sized umbrella on a very clear day with the Sun directly overhead. 

 

 

 

expectation dislocation

a quick minipost

I was listening to a  training technique discussion sports scientist Ross Tucker was having with a Royal Marines Green Beret.  Royal Marine training consists of a lot of what you might expect and adds a few areas you might not.  Expectation dislocation is considered one of the most important.   How do you psychologically and tactically deal with unexpected change?  How do you train people to handle it?

 

In science dislocation of expectations are considered a good thing, although they can be extremely frustrating at the time.  The overlooked, doing something stupid, being on the wrong track, the holy grail of unexpected discovery, and things mostly out of your control like equipment failures.  These things tend to play out more slowly than the battlefield or in sports.  Early in your career you make a lot of the stupid mistakes, find yourself on the wrong track and tend to overlook the obvious.  You learn with experience, but curveballs aren't uncommon and sometimes there's the taste of discovery.  

 

Sport offers dramatic examples.  I've had conversations with Sarah about preparing for and recognizing these dislocations in her sport.  How do you manage the psychological implications when you're trying to be "in the moment" at the same time?  Covid and the postponement of the Olympics had a huge impact on her.  But there are smaller examples.  Here's one of the most striking ones:

 

Sarah and Melissa face April and Alix in a semifinal in Cagliari.  Both teams are amazing - arguably the best in the world.   It's night with a chilly heavy rain.  At the 6:30 mark in the video Melissa goes down with a seriously dislocated shoulder.  After a doctor looks at it and a physical therapist re-locates it, she decides to go on - playing with one good arm.  The Canadians need to figure out local tactics and find a strategy as they go along. They only have their shared experience and all to brief moments of communication.  At one point a very fast spike targets Melissa's injured arm.  Something lights up in Sarah and she goes into her beast mode.  They win and go on to the gold medal match.  Unfortunately Melissa's arm isn't in great shape the next day and  they only take silver.

 

It's widely applicable.  Your car breaks down on a trip, a bad medical diagnosis ... any number of things ranging from very bad to very good.   How do you handle them in your life or your line of work?  How do you prepare yourself for these events?  These moments that can probe what we're made of.

 

personal social media usage experimentation

minipost

 

A few years ago I found myself spending far too much time on Twitter .. generally an hour to an hour and a half a day.  Time I didn't have.   For a month I went cold turkey, but was frustrated as there were a few people I only interacted with on Twitter and, following about 50 people in one of my fields was a good way to learn about new discoveries and papers.  I decided to limit my time, aiming for a half hour a day in two or three sessions. One would be devoted to hunting for new papers and the rest of the time would be the water cooler.   It's been mostly successful - I'll admit to hours of serious doom scrolling around the January 2021 coup attempt, but generally I'm under my thirty minute a day limit.  (I also have one day a week when I try to cut Internet access completely).

 

With that background I was fascinated to come across a report on some real-world experimentation by a group of about sixty college undergrads - a group known for heavy social media use.   Matt Salganik taught Sociology 204: Social Networks at Princeton last Fall.  He posted a report on Princeton's Center for Information Technology Policy's Freedom to Tinker blog:  

 

Improving Your Relationship with Social Media May Call for a Targeted Approach

 

From the introduction:

 

What students did:

Our class had about 60 students, from a variety of years and majors, and like most Princeton students, many of them were heavy users of several social media platforms. Each of them designed their own treatment and selected an outcome of interest. For example, some students were interested in improving their sleep and others were interested in wasting less time. In addition to these student-specific outcomes, we also had all students track two common outcomes that have been studied by other researchers: subjective well-being and time use changes.

This process of self-experimentation is a bit different from what social scientists normally do. Typically, researchers standardize the treatment, randomly assign treatments to participants, and collect data so that we can compare across participants and treatment groups. In our class, however, each participant was a researcher and designed a unique treatment for themself. Even though this is not standard for research, self-experimentation can be a good way to learn. The treatments students developed fell into three main groups:

Targeted limitation (about 45%). Students in this group restricted – but did not eliminate – their social media use. For example, students in this group did things like stopping TikTok use after 8pm and avoiding the Instagram feed (but still using Instagram for messaging).

Targeted increase (about 15%). In class, we learned about some research that suggests people who use social media actively—rather than passively scrolling—see an improvement in their well-being. So some students committed to increasing their active engagement with social media. For example, students in this group did things like posting 3 times per day on Instagram or direct-messaging at least 3 friends.

Elimination (about 40%). Students in this group eliminated their social media use altogether on one or more apps. Students who designed these treatments did things like delete Instagram or TikTok from their phone, and some actively replaced their social media use with another activity they valued such as reading the news or spending time with friends.

 

It's worth reading and non-technical.  It also offers some advice and techniques in the assignments section if you want to try learning about  your own usage.  It seems clear that there's a broad spectrum of positive and negative use patterns.