omenti

teaching kids science outdoors

I've been following Ben Blonder for some time.  He's a young career ecologist at Berkeley. Along the way he's been involved in projects teaching kids science.  He's just published a new book on teaching science to kids outside.  Trust me - Ben knows what he's doing and has involved some of his collaborators in the book.  (I know his dad well ..  Greg describes this as a true labor of love, and it shows)

Place-Based Scientific Inquiry

The online/downloadable version is free.  If you buy a copy, profits will be donated to science education. 

It looks like the focus is grade 3 → 12.   It's probably good for those of you doing a bit of amateur science for fun.

recommended!!!

 

 

 

 

magnets and a most dramatic moment

The opening ceremony of each Olympic game is filled with pageantry and sometimes, with the lighting of the cauldron, drama.  In my mind the most electrifying occured in the 1992 Barcelona games when Paralympian Antonio Rebollo performed some serious diablerie. 

Across the ocean in New Providence, New Jersey David and Mary watched the scene on a small black and white television as they shared pedaling duties.  David was pedaling at the time and gasped.  Fortunately there was a flywheel.

 

Their parents didn't allow television in the home, but both of them had been involved in competitive kayak and canoe events.  Lynn had been an alternate for the Montreal Olympics.  Introducing Mary and David to the Olympics was a good idea, but Al decided to make it educational. The kids would be given an exercise bike, a generator, access to a television and help from their mechanical engineer father and mathematician mother.  They had a few weeks to work things out.

 

When the the friction wheel generator was finally adjusted and working, they were shown how much power they produced and how much power various televisions used.  A twelve year old could keep a small color set going for a short time, but that was it.  They wisely chose the black and white set.  Through trial and error they ended up with a bicycle chain transmission and abandoned the exercise bike for one of their own on a homemade stand. They could now produce nearly twice the power for the same amount of perceived work.  A flywheel was added to make everything smoother.   They had something by the opening ceremony and the kids spelled each other off and developed an amazing sense of how long the commercials lasted.  They saw the torch lighting.¹

 

It's too bad they had a standard generator.  Something with better magnets would have had increased efficiency.  Not enough to move them into a color set (if they were a few years older and more athletic they probably could have managed), but certainly a better experience.  The strength of the magnetic field in a generator or motor is centrally important.  The strongest fields come from superconducting magnets, but they need to be cooled to near absolute zero rendering them impractical for most applications.

 

Electric vehicles use either induction or permanent magnet motors.  The permanent magnet designs tend to be lighter and are more efficient.²   There's a rub.  You're trying to optimize cost and magnetic field strength (among other things).  Rare earths like neodymium work much better than the cheaper ferrite-based magnets and have generally taken over the medium and high end automotive market.³ 

 

The problem with rare earth materials isn't that they're rare .. they fairly comment.  They are, however, unevenly distributed and difficult and toxic to mine and process.  Most of the active mining and processing is in China and it's an environmental disaster.  The US had a single mine in California in the fifties.  Since then it's had t an up and down existence including being closed for economic and environmental reasons.  With the interest in EVs it's back in operation again  and the US has gone from 0% of the world's production of neodymium to about 15% in about seven years.  In theory the mining and processing and safer and less toxic than the Chinese effort. Production should increase in the future.  The US is also largely unexplored - serious mineral exploration has only just resumed after a 60 year hiatus. 

 

The higher cost has some companies, notably Tesla, talking about going to ferrite permanent magnets.  They'd be heavier, less efficient, but would be cheaper and may be the core of lower-end vehicles.  Another alternative is to use a more efficient vehicle.  Electric bicycles and other micromobility solutions use small motors.  You can build 50 to 200 electric bike motors with the materials from one Tesla-class motor.  Not only that these vehicles are very practical for the short trips that dominate much of our mobility needs.  Sadly some areas have saddled themselves with transportation infrastructures that encourage inefficiency.

__________

¹ Mary continued in the families sport tradition and went to Princeton on a fencing scholarship.  She found she was interested in aeronautical engineering and went on for a Ph.D.  I heard she had something to do with the rotor design on the Ingenuity helicopter currently flying on Mars. 

² There are often questions about how permanent magnets work.  Most people have seen electromagnetic induction in school.  A current flows if you move a magnet in a coil of wire and a current through a wire produces a magnetic field.  Permanent magnets are more difficult to talk about .. I've done it at least once, but this short video is a nice intro.

 

³ There are other rare-earth based magnets, but a neodymium alloy is the most common.  It's an allow of neodymium, iron and boron - Nd₂Fe₁₄B - that forms a crystalline structure.  They have widespread use outside of EVs.. GM and Sumitomo Metals independently developed them about 40 years ago to get away from much more expensive and brittle samarium–cobalt magnets.

There's a lot of talk about tetrataenite (an iron-nickel structure) permanent magnets.  In theory they have better magnetic characteristics than neodymium alloys and should be much cheaper, but they're off in the future.  If they happen, expect some unhappy rare earth mining companies. 

 

rogue waves

 It's worthwhile just sitting on the beach sometimes.

 

I used to take weekend bike rides to the South Beach as part of a cycling club when I lived in Pasadena.  Mostly wasted, we had a variety of ways to spend a a couple of hours on the beach as we recovered enough for the trip home.   Some played frisbee, some played in the water, some read, I mostly watched.  There were so many wonderful questions!  What determines the frequency and height of the waves?  What determined where they "broke"?  Why can surfers move so quickly (it turns out to be the fin)?  Why do beach volleyballs sometimes corkscrew and suddenly drop?  How do the gulls "wave surf"? Suddenly fluid mechanics became interesting.   Mostly I've done other things since, but every now and again an interesting problem crops up and the techniques have been useful in areas that aren't obvious on first glance. 

 

Recently I've come across a number of papers on rogue waves. There are a couple of primary mechanisms that describe these beasts and an understanding is emerging.  There's also a good deal of experimental work. Some day soon we'll have coarse warnings (try not to use this patch of water for the next eight hours).  Localized predictions are much more challenging, but why work on something that isn't?

 

Steve Strogatz posted an excellent non-technical podcast chatting with Ton van Den Bremer - one of the leaders in the field.  Here's a link along with a transcript (I recommend the audio as there's content in their voices).

 

 

 

 

ai and humanity

Om wrote an interesting piece on what AI (whatever the term means - it's being used almost without meaning these days) has in store..  will it eradicate humanity.  I'm on Om's side.  He raises the more interesting point of what it does to humanity.  (I believe AI not only has the potential to harm, it is already doing so.  That's another discussion.  The real existential threats at this point are global warming, nuclear weapons and pandemics.) You can ask questions of any technology.   Let's focus on technologies that augment human capabilities.

 

The inventions of drawing and writing represented our first external memory systems.  Plato believed writing would erode real communication.  From his dialog between Socrates and Phaedrus:

 

And so it is that you by reason of your tender regard for the writing that is your offspring have declared the very opposite of its true effect. If men learn this, it will implant forgetfulness in their souls. They will cease to exercise memory because they rely on that which is written, calling things to remembrance no longer from within themselves, but by means of external marks.

What you have discovered is a recipe not for memory, but for reminder. And it is no true wisdom that you offer your disciples, but only the semblance of wisdom, for by telling them of many things without teaching them you will make them seem to know much while for the most part they know nothing. And as men filled not with wisdom but with the conceit of wisdom they will be a burden to their fellows.

He goes on to compare written text with a painting

You know, Phaedrus, that is the strange thing about writing, which makes it truly correspond to painting. The painter’s products stand before us as though they were alive. But if you question them, they maintain a most majestic silence. It is the same with written words. They seem to talk to you as though they were intelligent, but if you ask them anything about what they say from a desire to be instructed they go on telling just the same thing forever.

It's ironic that his dialogs only exist because they've been written down.

 

The external memory system of writing improved by going to paper and then to bound books and cheap books with the printing press.  We had to learn how to read to access this memory system, but most societies feel that's an appropriate use of time.

 

I wouldn't be able to do much of anything without glasses - a human augmenting technology that uses a bit of grinding and the properties of glass to perform complex realtime optical computations to move my focal plane to where it should be. 

 

In high school I learned how to use a slide rule to help with multiplication, division and trig functions. Little did I know it would give me an intuitive sense of how logarithms work along with vastly improving my ability to do mental approximations.  I still find I'm more creative in early problem building if I'm sketching on a blackboard and using a slide rule rather than relying state of the art tools like Mathematica. 

 

As a teenager I made use of the postal system to communicate with two mentors in what turned out to be one of the most important educational experiences I've experienced. The latency of the postal system turned out to be  important as it  gave more weight to each leg of the communication.  A great deal of introductory math and physics is available online these days, but it would have been too easy and I would have probably learned at a superficial level.

 

My style of thinking turns out to be very visual and using my imagination, perhaps aided by some sketches and wrestling with equations by hand and visually in my mind gives more insight than visualization tools, although they can be very useful at later stages.

 

There's great value in thinking and creating.  Making something out of wood with simple tools rather than ordering it premade or 3D printing it.  Learning how to play a musical instrument rather than just listening.  Communicating with a friend over time with pen, paper and the postal system rather than a video chat.  And then you're doing your taxes (at least in the US), you're probably using a tax program on your computer.  All of these involve augmenting technologies that have been created by someone else and all require different approaches. Enjoyment of the process and the final product may not be aligned and that can be a good thing.

 

Om and Bryan use photography to augment how they see the world around them.  My sister does the same with her paint brushes and canvas as well as photography.  All of these people use machine learning embedded in their cameras as part of the creative process, although they may carefully control its use. 

 

There may be great value in using an LLM to help with a programing task or organizing information.   If we're lucky we have the freedom to select the most appropriate technology for the task.  But we should consider these choices carefully.  What's bad is when a technology with bad side effects or even harm is used without our knowledge and consent.