omenti

the third wave

Electric cars are beginning to take off.  If you need to replace your old car they may be a good choice as maintanence is potentially much less expensive.  They're usually a bit more environmentally friendly than a conventional car of the same size, but not by much. There are much more cost effective ways to lower your carbon footprint. One is replacing local commutes and errands with a bicycle. 

 

We may be at the beginning of a third wave of bicycling in the US.  This time it's a bit different with pedestrian, human powered, and human-electric hybrid bicycles in a category that's called active transportation.  I'm not so sure it will take hold in the US this time - after all, our second wave fizzled in the 70s.

 

The first wave came with the invention of the safety bicycle in the 1880s.  Suddenly cheap transport that could extend your walking range by a factor of three or four appeared and bicycle fever swept the US and much of Europe.  I've written about it a few times and won't say much other than it was an important component of women's suffrage in England. It also lead to widespread mass production and engineering leading directly to the automobile and airplane.  

 

The second wave began in the late 1960s - first in the Netherlands, followed by the US, and slightly later by Denmark.  None shared a common trigger.  The Netherlands was a reaction against the beginning of affluence that came in the mid 60s that flooded the streets with cars.  The narrow streets, children playing and cars were a nasty combination and people reacted strongly closing streets and going back to the bicycles they had used since the war.  The US boom was fueled by the green movement - particularly in university towns.  Denmark's was a reaction to the oil crisis.  The Netherlands and Denmark stayed the course building physical and social infrastructure that favored cycling in cities and small towns. Progress was slow, but by the early 90s the bicycle had become an important piece of transportation.

 

The US started much more aggressively, but fizzled for a number of reasons shortly after the mid 70s. Carlton Reid wrote a piece on the US boom that failed - a short recommended read!

 

Now something has changed - the ebike.

 

A first ride is astonishing.  They're not motorbikes - you pedal and an electric motor adds power to your muscle power.  You can set the level of added power to levels better than any Olympic bike racer. Hills flatten and the distance you're willing to ride doubles on average.  The efficiency of a person on a regular bike is amazingly high - an ebike typically improves it by a factor of two. You're still get exercise and it's much more practical than a Peloton if exercise is the goal.  Currently there are more customers than bicycles..  

 

So they make sense for you?  Probably the most important consideration is safety. Women and children are usually seen as the two indicator species - when at least half of the adult riders are women and most of the children walk or bike to school..   Women and children already dominate bike riding in the Netherlands and Denmark.  Bicycle racks were removed from schools in my New Jersey town as bike riding was considered too dangerous by the school board.  They were afraid of lawsuits if they encouraged bicycle use.  Some of you live in areas with very low traffic densities and safe conditions. For others the question is how to build a safe transportation infrastructure. 

 

You don't want to share the road with drivers who aren't aware of you, don't know what it's like to be on a bike, and may have more legal protections than you.  A variety of approaches can create safe cycling - certainly European counties have taken differing approaches.  A commonality is traffic calming.. speed limits should be 20 mph or less if bikes and cars share a lane.  Bikes on more heavily traveled streets should have physically separated lanes.  Paris has shown this isn't difficult or expensive.  The most cost effective way to come up with real estate for separate bike lanes is to eliminate car parking and the experiment has been very popular to the point where the changes are becoming permanent.  The city is on its way to removing about 70 percent of parking.  

 

Assuming the risk of cycling is low enough for you, it's important to find a good ride as there are a lot of poorly built bikes out there.  A good ebike that should last a decade will set you back at least $2.5k.  These usually have a similar design to a conventional bike  They're great for commuting and just riding around, but consider a cargo bike if you're serious about replacing a car on local trips.  The past few years has seen a revolution in properly engineered  and practical electric cargo bikes.  Good bikes in this class tend to be spendy starting around $4k.  I have a favorite, but these are individual choice and spening time at a good bike shop is important.  

 

a promotion video of a very good cargo bike illustrating some use cases - you can easily carry two hundred pounds of cargo without worrying about balance, power or overloading.

 

Back to that third wave - will it continue or just fade?  Many regions in Europe already see a lot of cycling and the trend will only increase as automobile use is minimized in the cities.   North America is more difficult as the infrastructure and expectation supporting cars and city layouts are somewhat rigid.   Emerging cities, mostly outside of North America and Europe,  have a choice of city layout and transportation infrastructure.  It will be fascinating to see how and where active transportation fits in.  And there are other practical but non-conventional transportation modes - and I'm not talking about self driving vehicles...  

 

 

ultra high energy cosmic travelers and beach volleyball

In 1912 Victor Hess was testing a hypothesis that this new fangled radiation came from rocks in the earth.  He built a simple detector and made a series of ascents in a hydrogen balloon.  The higher he went, the higher the radiation levels.  The radiation was coming from above rather than below - he had discovered cosmic rays.  

 

Cosmics proved frustrating to study. Very high energy particles - usually protons or light nuclei -  hit the upper atmosphere where they'd strike a nitrogen or oxygen atom. That produced a shower of particles which would strike other atoms spreading the shower.  It was difficult to say where the initial particle came from or even how much energy it had other than very high energy cosmic rays produced showers that spread out more than lower energy events.

 

By the 1960s physicists started building arrays of small water tanks and spreading them across large open areas.  The tanks could detect small flashes of light made by fast moving particles moving faster than the speed of light in water.  More tank signals at the same time meant a larger shower.  By seeing how much area had been impacted by the shower it was possible to infer the original cosmic's energy.  

 

By the 80s more sophisticated techniques began to lift the curtain a bit.  Cosmics cover an enormous range of energy ranging from that of particle accelerators of the 1970s and up.. way up.  Nature had built some amazingly power accelerators and we were building detectors for them.  Learning where these accelerators are and how they work may teach us about the fundamental nature of the Universe.  The focus shifted to extreme events over 10¹⁸ electron volts - that's over 100,000 times more energy than the highest energies produced in the Large Hadron Collider at CERN.  These are among the fastest objects with mass in the Universe.

 

The really powerful ones are fairly rare.  A square kilometer of the Earth will see about one 8 EeV (an EeV is 10¹⁸ electron volts - an exaelectron volt) per year.  One array is about 3,000 square kilometers so it would see nearly ten of the 8 EeV events per day.  It's effectively an enormous digital camera with car sized pixels spread over a huge area.   Even higher energy cosmic rays occur less frequently - you expect a 100 EeV event per square kilometer per century.

 

It turns out the amount of kinetic energy an apple falling from a table is about one joule - that's about 6 EeV.¹   These tiny incident cosmic rays have energies in ranges we're familiar with.  Sarah can serve a beach volleyball at around 80 kilometers per hour giving it a kinetic energy of about 70 joules or 420 EeV.   In 1991 an event known as the Oh My God particle was detected in Utah with an energy of about 320 EeV.  That's only a bit less than Sarah's serve and about the same as a 60 mph baseball.  It's almost certain higher energy cosmic rays exist, but we just haven't found any yet.

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¹ An electron volt is a tiny amount of energy that's used mainly to study energies at the molecular and atomic level.  A light photon useful for photosynthesis is on the order to 2 electron volts.  A joule something more on the human scale..  70 for Sarah's beach volleyball serve and 140 for a 100 mph.  fastball.

 

right out of buckaroo banzai

mini-post

You probably know Pluto isn't considered a planet anymore.  In the 90s objects of similar size were discovered in a region outside the orbit of Neptune known as the Kuiper Belt.  Several of their features set them apart from the first eight planets so it made sense to call them by a different name - dwarf planets.  One of the major figures in these discoveries is an astronomer who specializes in the solar system and how it came to be.  Mike Brown killed Pluto. Neil deGrasse Tyson only popularized Pluto's demotion.  Mike took a lot of flak including hate mail from children.  His young daughter told him he'd have to go and discover the ninth planet to make up for it.  

 

Konstantin Batygin joined Mike in the discovery of an unusual clustering of the orbits of some extreme trans-Neptunian objects.  These objects are well beyond the Kuiper Belt - generally over one hundred times farther from the Sun than we are.¹  They hypothesized a very large ETNO five to ten times as massive as the Earth in a very elongated orbit 200 to 400 times as far from the Sun as we are was causing the clustering. 

 

The hunt for Planet Nine has been a huge challenge as it would be extremely dim.  There are ideas where it may be, but so far nothing.  The search continues and other discoveries are being made.

 

The real reason for the post is to show scientists have lives. Konstantin happens to play guitar in a small rock group.  Eduardo Marturet and composed a piece of music for symphony orchestra and electric guitar in honor of Einstein's birthday.  So why not have a physicist as guest soloist?   This past Sunday Konstantin joined the Miami Symphony Orchestra by video link for the performance.  Right out of Buckaroo Banzai.

If the piece isn't to your taste you can scroll around - say to about the five minute mark - and watch Konstantin play with his slate blackboard in the background (physicists and mathematicians  - even the young ones - still use chalk)

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¹ A quick way to think of the size of the solar system is to consider the distance of planets from the Sun in terms of astronomical units.  One AU is the average distance of the Earth from the Sun.  So moving out from Earth and rounding:

Earth                   1.0

Mars                    1.5

Jupiter                5

Saturn                 10

Uranus                20

Neptune              30

Pluto                    30 - 50 

hacks and homebrew

About twenty years ago a Summer student I had a few years earlier called to talk about digital cameras.  She was waiting for the cost of "good enough" sensors to drop, but was excited by the prospect of eliminating the film costs.  Soon we were talking about the total cost of taking a photograph.  There was the cost of a trip if you wanted one from the North rim of the Grand Canyon and a photo of the Earth from the Moon would cost billions - less if a robot took it.  There was an interesting optimization question:  how far up could you go to take a photograph for a fixed amount of money?  One of us suggested five hundred dollars.  An airline ticket could get you to nearly 40,000 feet with some planning.  But a weather balloon?  Now we had something to think about!  An hour of dreaming and scheming quickly went by.  It was a fun little gedanken project to play around with.  I moved on to other things the next day and mostly forgot about it.  She didn't.

 

A month later, the phone rang - something about scoring a dozen "Barbie's First Cameras" for ten dollars.  "That's four hundred and ninety dollars to go...you in?"  The cameras were cardboard disposables with with a plastic lens and shutter assembly and about a dozen exposures worth of color Kodak film.  They were pink.  Of course I was in. 

 

I found a damaged Trimble GPS with a broken screen for fifteen dollars.  The electronics worked so it was only a matter of getting the signal out and sending it to the ground.  She was responsible for programming an ancient Z80 microprocessor and working out a mechanism to push the shutters.  I repurposed an old amateur radio.  We modified a small styrofoam box with a battery and resistors to keep everything warm.  Then it was finding a weather balloon and helium.  

 

This leaves out dozens of details. Many were ugly, but good enough rules.  This would be easy these days with electronics available to hobbyists. You could do a much better job for under a hundred bucks without the balloon, or just send up an old smartphone.

 

Three of the cameras worked.  This is the best photo from 26,900 meters above Ohio.  

 

The goal of engineering is to find a good, hopefully great, optimization to a problem with several competing requirements.  Usually it's impossible to optimize everything. A car might have cost, performance, fuel economy, safety, time to market, and appearance as desirables. There's no way to maximize everything.  Usually the problem is constrained - a supercar throws cost and fuel economy out the window and turns out to be easy to execute.  Mass market cars are much more difficult.  Great engineers excel at this type of optimization. I don't have the necessary talent and experience.  Fortunately I live in a different problem space.  

 

Experimental science is generally underfunded.   Not only is it difficult to justify buying some gizmo, but sometimes the gizmo you really need doesn't exist.  You need to modify something you already have or can borrow or just build something.  The result is often crude, but it works.   Many physics departments make sure you can qualify for a key to the metal and electronics shops. These days knowledge of 3d printing is almost assumed.  More specialized skills and rules of thumb come with what amounts to the apprenticeship otherwise known as the PhD program. 

 

I don't have an exhaustive knowledge of homebrew equipment, but you see it almost everywhere.   Here are a few I've used or have built

 

° We had a particle detector with an internal atmosphere of argon, krypton and xenon. A cheap way to measure their relative concentrations is to measure the speed of sound in the gas.  In the 70s Polaroid had a camera with an ultrasonic rangefinder.  It sent out a short ultrasonic pulse and timed the return of the reflection to adjust the focus.  Damaged cameras were cheap and we had existing electronics that did a much better timing job.  There are probably a dozen other ways to do this, but it worked.  I later used one of these transducers to listen to bat calls. It led to a series of bat detectors I built as a hobby.  Again - not elegant, but workable and I learned enough to ask informed questions about bats.

° If you need a high voltage, low current power supply, the flyback transformer in an old CRT color TV gives you about 25,000 volts and is free if you can find one in a junk pile.  

° Many experiments need to minimize the effect of the Earth's magnetic field.  Usually a set of three Helmholtz coils - three pairs of circular wire loops current runs through.  Each pair generates a uniform magnetic field.  Three of these pairs, each at right angles to each other, allow you to create a field that counteracts the Earth's field.    I once used Hula Hoops as forms to wind the wire.

° Immersion cookers (sous vide) in a styrofoam lined box are a good way to keep a liquid bath at a stable temperature above room temperature.  Much cheaper than commercial heated water baths.

° Some biology labs I've visited use household refrigerators with plastic baffles and better thermostats saving thousands per over lab grade refrigerators.

° The performance of a small anti-vibration table can be improved by "floating" it on powerful speaker magnets with coils connected to an audio amplifier and simple feedback circuit.

° Home photo scanners (Canon, Epson, whatever) can be hacked to build the guts of a table that can position something lightweight in two dimensions to better than a tenth of a millimeter.  An "x-y" table.   For the price accuracy and repeatability of these scanners are remarkable.

° At Bell Labs in Murry Hill, NJ a prototype x-ray lithography tool created a x-ray beam by shining a beam of electrons on an iron target.  The target? - a VHS tape driven by the tape mechanism taken out of a VCR.   The iron particles embedded in the tape were perfect for the job.  After about ninety minutes a fresh blank tape would go in. 

° Back to my student days at Brookhaven National Laboratory.  One experimental area produced a clean beam of neutrinos. A beam of protons with a target producing a lot of particles including neutrinos. Neutrinos rarely interact with matter - a beam of them would lose about half its intensity after passing through through a wall of lead a light year thick. The problem is some of the other particles will travel several kilometers through the air.  The trick is to put a lot of mass between where they're produced and your experiment.  Somehow BNL managed to convince the government they should store about 50,000 tons of armor plates from WWII ships in a line at the lab ... you know, just incase there's a strategic need for iron in the future.  It's covered with dirt and has nice wild flowers growing on it.  

° Commercial camera lenses can be amazing.  The University of Toronto's Dragonfly array uses two clusters each comprised of 24 400mm F2.8 telephoto lenses to make the equivalent of a 1 meter f 0.4 refractor.  The later would probably cost more than ten times as much - if it was possible to even make it.   It does things other instruments can't and has made important contributions to astrophysics.  

 

I'll stop here. Experimentalists often have to be cheap.  Sometimes it's invention, sometimes it's just getting something working.  It's definitely not engineering - a good engineer would throw up their hands.

 

looking at the algorithmic economy

minipost

If you think about how society and the Internet, you probably know about Joan Donovan of Harvard's Shorenstein Center.  Among other things she's known for rejecting the notion of the "attention economy" as being somewhat gas lighting.  Instead she uses the phrase "algorithmic economy."

Andy Revkin of Columbia interviewed her this past Friday as part of his Sustain What series.  She talks about the possibility of a path to a public interest Internet while safeguarding speech.  Also how disinformation memes develop and need to be watched and how the current control of interests on the Internet fail.   You may or may not agree with her, but she's one of the deeper thinkers in this area and this is a particularly clear introduction to what she's about.  Andy does a great interview job, pushing back here and there to go deeper.  An excellent way to spend an hour.