omenti

when not keeping your cool is a virtue

Why are we paying someone to heat parts of our house we aren't in?

 

This was one of my Dad's  deep questions.  Two adults, two kids and three dogs in a small house subject to Montana winters. Cold snaps could be deep and long - a week or more with highs well below 0° F ( -18° C) weren't uncommon.  More impressive were the lows:  -30° F (-35°C) came at least once every Winter and record lows were below -40°.  Dressing for it was a necessary skill.  Inside the home my Dad controlled a powerful technology - the thermostat.

 

When people were around during daytime the thermostat was set to 62°.  The nighttime setting, from 9 PM until the first person got up at about 5:30AM,  was 55°   If people were out of the house  the setting was 52°.   As far as I could tell these were his fundamental constants.  Warm clothing, sweaters, quilts (my parents cheated and had an electric blanket)  made it comfortable and sometimes even too warm.  There was only one thermostat and a few areas of the house were always a bit colder or warmer.  The dogs found the warmest regions at dog level. They also had warm blankets that they'd drag around where needed.

 

Since then I've learned a bit about home heating.  Some of the best information on home energy measurements comes from England.  They found standard modern construction homes see seven to ten percent energy savings for each degree celsius drop between 15°  and 20° C .  Lowering the thermostat setting from 70°  to 61° (21° to 16° C) could translate to 30 to 40% reduction in your heating bill.  It could also make a serious impact in places facing severe gas shortages this coming Winter.  

 

There are other tricks.  A big key is to heat the people and not the airspace where they aren't.  We had a small, partly finished family room in the basement.  We were there a lot during the Winter as it was the warmest room in the house.  Four people and three dogs radiated body heat along with four 150 watt lamps in the ceiling and a small electric heater (pro tip -- if you have a male dog, don't put one of these on the floor).  My Dad had a tendency to drop the thermostat to nighttime levels when we were down there. Most of our books lived there and a long work bench allowed my sister and I to work on homework and hobbies.  There was a TV, but it didn't get used that much.  It's where we told stories.¹  In the Summer the warm rugs on the floor came up and the room was a naturally cool place to escape the heat of the un-airconditioned home.  

 

The English studies I came across note the average English home was heated to 13° C (55° F) in 1970 rising to 20° C by 2000.   Our house wasn't all that different from the average English house. 

 

There are many other tricks for saving energy - insulation, heat pumps and so on, but they won't happen in Europe before this Winter for most people.  Insulation, done improperly, can be a two edged sword.  Forced air heating, the most common type in the US, fills the house with heated air. Insulation keeps as much of the heat as possible inside.  The problem is that often the air is trapped inside.  Stale air can be unhealthy (VoCs, high CO₂ levels, etc.).  There's a simple technology that can help - in fact you needn't look farther than your nose.  Your nose is a heat exchanger.  Cold air comes in and is heated up without releasing much of your body heat when you exhale.  Most industrial buildings and some homes have heat exchangers - they're required by many building codes to keep super insulated homes healthy.  Something to look into if your place is heavily insulated.

 

Localized radiant heat allows you to circulate some air from the outside and still be comfortable - you're heating people rather than the air.  You've probably noticed Scrooge's chair,  in many adaptations of A Christmas Carol, has a high back curved sides.  These were common in the Victorian era.. sit in front of a fireplace and focus the warmth. People have experimented with heated chairs with good results - notably work at Berkeley in the past decade.²  (They also designed and tested cooled chairs for the Summer).  People who live on the Japanese island of Hokkaidō modify the short legged Japanese family tables by putting a blanket over them and a small heater underneath.  I've used one of these visiting a couple from Sapporo when they were living in NY and was amazed how well it worked in their otherwise chilly house.  Teenagers like them for other reasons when their parents aren't home.  

 

In short there are many paths to clever - no silver bullets, but a lot of silver buckshot.  Twenty or thirty percent conversation levels are quite realistic for many people.   I won't mention adventures in an unheated 15 foot trailer with three dogs at -25°F (my mother thought colder temperatures were dangerous)

__________

¹  Nordic families seemed to tell a lot of stories.  Our heritage isn't Nordic, but many of our neighbors were and some of that rubbed off on us. 

² Here's an example and test of a heated/cooled chair. You could make one of these.. I haven't seen anything commercial.

 

 

 

inspirational chindōgu

Every now and again someone asks for advice on educational toys, projects or activities for their kids.  For a number of reasons I'm precisely the wrong person to recommend this or that.  It's not that I don't care .. I worry a lot about kids who enjoy math and science until they're 11 or 13 and then suddenly it becomes hard and boring.  This seems to happen to girls more than boys, which is just wrong.  Too many programs  focus on the top ten percent  and too few on those who could use a different way of seeing things.  I'm not terribly interested in the number of STEM graduates from college.  Rather, it's far more important having a literate society.

 

There are a few excellent motivators on YouTube.  Physics Girl is great, but her level is high school and beyond. For preteen and teenage girls (and many others) Simone Giertz is great.  She's a bit nutty, hyper-enthusiastic and has built a good business inventing useless things.  (She's also Swedish.  I defy you to find that in her accent.) Many of her projects are too advanced for a 13 year old to recreate, but the basics are there and recreating them isn't the point.  She wants to make you think about mechanical things differently.  She fires imagination with her humor.  Finally a huge bonus is that she admits to and highlights her mistakes.

Here's her latest - musical bubblewrap 

 

31 is the new 35

Andrew Revkin and I had a brief exchange about the power of labels.  Both of us object to the phrase "climate emergency."  Even though it is an emergency that could escalate into an existential threat, people don't respond to labeling longer term threats as emergencies.  I've been suggesting we've entered an adaptation epoch.  Andrew, a much better communicator, is still searching.

 

The past two or three years have taught us short term temperature excursions can be dramatic.  Last year the Pacific Northwest recorded previously unheard of temperatures -  the highest in the area in at least 7,000 years and probably much longer.  This Spring it was South Asia.  Last week record heat came to England and parts of Europe.  These events are probably going to be more common and time goes on and greenhouse gas levels continue increasing. 

 

Wet bulb readings of 35°C (95°F at 100% humidity)  have long been considered unsurvivable.  A person in good physical shape would probably die in a few hours. Such events are extremely rare. Until the past decade they've only been recorded a few times and then only for an hour or so.  They're increasing in frequency and length - mostly in the Indian subcontinent.  Finding cooler spaces for people is a matter of life and death.  

 

It's become clear the 35° number was something of a guess.  Recent careful work shows it's more like 31° for young people in good physical shape.   Older and compromised people have lower limits.  The Tokyo Olympics had periods with wet-bulb temperatures in the upper twenties. Athletic performance during these periods was certainly compromised (I saw it happen to a friend). 

 

What can be done?  Cities suffer from heat island effects.  All of the asphalt and concrete increases the local daytime temperature and holds them at higher levels at night. (hot nights may be harder on the body than hot days).  Air conditioning helps, but it costs money and a power grid that not everyone has access to.  Reducing the amount of asphalt and concrete while planting trees can make a big difference.  It's a great justification for reducing the number of cars and roadways in cities (green spaces are a key motivating reason for the dramatic change currently underway in Paris).  Unfortunately green spaces are usually linked to wealth.  In many places racism and redlining have produced some of the worst heat islands.

 

There are other tricks that are easily implemented.  White paint  on roofs can make a difference. Paint that holds up to temperature and monsoons for the better part of a decade isn't cheap, but is becoming more popular.  In Western countries more reflective shingles are appearing. Some of these look fairly normal, but are highly reflective in the infrared and can make a difference in cooling bills. 

 

And you can send some of the excess heat directly to space.  

 

If you're in a very dry area go outside on a clear night and look up.  Feel the cooling on your face.  Now hold a piece of cardboard between your face and the stars.  You'll notice a warmer feeling.  Remove the cardboard and your face gets cooler. 

 

Your body glows - you've undoubtedly seen infrared photos and videos of people.  We radiate photons at a variety of wavelengths, but it peaks around 9.5 microns - about twenty times longer than visible light.  The  atmosphere is transparent to visible light and also from 8 to 13 microns.  Photons from our bodies can radiate to space.   Deep space is really cold (a bit over 2° above absolute zero) so your face is radiating some of it's heat directly to space - enough that you can feel the cooling.

 

Clever material engineering has produced materials that are good at absorbing the heat around them and then radiating it into space. It's enough to reduce cooling requirements - at least in places with very dry atmospheres.  There's still work lowering costs and making the surfaces last longer, but it's something else to try.

 

Back to the idea of an adaptation epoch. Many things will need to be tried and efforts will stretch for generations.  There's enormous opportunity.  It's both sad and dangerous there's so much 19^th century political inertia, but I'm optimistic more clever people, organizations and governments will finally emerge.  As a species we don't have a choice if we want to survive.

 

repairability

My Dad was a Ford man.  More specifically the Ford Falcon.  It was a simple compact car with a 170 cubic inch displacement straight six coupled to a three speed manual transmission.  It scored on the high end of the Mobil fuel economy test - about 19 miles per gallon when the average sedan was in the 12 to 14 range.   But what he really liked about it was how repairable it was.  Not only was it simple to work on, but most of his friends had cars with the same engine and transmission.  If something needed fixing we could usually do it ourselves using tools borrowed from one of his friends.  For more serious repairs there were specialized tools from Strobel's A to Z Rental, garages or (shudder) the Ford dealer.

 

The simplicity of cars of the day was balanced by crude manufacturing tolerances.  Pistons fit so poorly in the cylinders that the first 500 or 1000 miles were done with great care using an abrasive oil to polish the parts into shape.  It made a big difference in gas mileage and extending the life of the engine past 50,000 miles.  

 

The dual gas shocks of the 70s opened the market for better cars that used higher precision design and manufacturing processes.  That and the beginnings of cars that crumpled to absorb energy in crashes made simple repair much more difficult.  The amateur mechanic had largely vanished by the 80s.

 

Clothing and shoes were expensive back then.  Quality construction and repairability were important considerations while shopping.  Tailors and dress makers were common.  The same was true for appliances.  Vacuum cleaners, toasters and anything electronic could be repaired at home or the local repair shop. 

 

There are exceptions today .. Jheri makes her own clothing or buys high quality pieces with the intention of buying very little as she hopes each piece will last at least a decade.  She's abandoned fashion and has created a style very much her own.  I suspect some of you - Om for example - have a similar philosophy.    But while it can be done in clothing, it's next to impossible when electronics are involved.

 

By the time I was fourteen I had three or four black and white TVs.  None of them worked - watching TV wasn't interesting.  The tubes, capacitors, transformers, switches and so on..  now those were useful!  I designed and built a few radios and a stereo amplifier.   It was straightforward and the experience taught me a lot about electronics.  Now I look in a computer, TV or radio and see only massive integration.  It's still possible to build things, but design is much more difficult. Learning about circuit elements is probably better done with computer simulations.   

 

The right to repair movement has grown in recent years.  I welcome  it for some products, but given the tight integration of hardware and software  I worry it may not be as generally attractive as proponents claim.  

 

Smartphones are a case in point. Apple is infamous for discouraging third party repair.  You can order a kit from Ifixit to replace a screen, battery and some other parts.  It can work well if you have a bit of experience and Ifitit is upfront with the degree of difficultly. You lack the tools and technique to take apart, replace and reassemble the device to design specifications.  

 

My personal results are mixed.  I easily replaced the battery (twice!) on my first day, first generation iPod.  The battery and screen on my out of warranty iPhone 5 was a different matter.   After five hours of frustration I was left with an operating phone, but the case was fitting tightly and whatever waterproofness was gone.   The misaligned case also interfered with the physical buttons on the side.  I did get another year and a half from the phone though.   It could be worse.  I know someone who replaced the battery on an Android phone with an inexpensive battery from Amazon.  The phone got very hot during charging and caught on fire when he took it apart to pull the battery out.  It filled his place with acrid smoke, but fortunately only destroyed the phone and wastebasket

 

Apple is afraid of regulation so they offer repair kits for some of their devices.   The Verge documented a battery replacement.  You get a huge repair kit with a large hold on your credit card until Apple gets the kit back.  The process probably works well if you're skilled at working with small electronic devices, but this isn't for everyone. Given the cost of shipping I suspect Apple's losing money, but they're also trying to make a point of what it takes to do a high quality repair.  Of course a third party repair shop could buy the tools and perform quality repairs and I suspect that will happen.  Lower quality shops abound, but your phone or laptop may be a bit wonky afterwards.

 

We need to understand what's repairable, what's sort of repairable, and what's not.  Easy to repair smartphones have been offered but they're generally expensive and lacking in features.  I suspect smartphones, laptops and smartwatches are probably moving to a subscription model anyway.  Clothing and some appliances could made for longer lifetimes and repairability.  Then again convincing consumers and companies to move away from a consumption model is a huge, but very important, challenge. 

 

I've mentioned clothing, but should follow-up with other product areas where design for long life, repairability and upgrading is important. It's generally expensive, but in the long run can have advantages.  You may live in an example.

 

 

who are you going to call?

Drop two pieces of bread into the toaster and push the lever down.  You go about your business getting the rest of breakfast ready and then, after a few minutes, two pieces of toast pop up.  Have you ever thought about what's going on?

 

We usually think about the toaster receiving the bread and giving it back to us after a few minutes - electric heating somehow.  Someone from a few thousand years ago might wonder where the bread came from and what kind of magic transformed it into something similar but different after a few minutes.  He might wonder if the lever was some kind of prayer or incantation.  We can examine the process at a variety of levels and can find considerable depth.  We know the cord is plugged into a socket which has a path though a series of transformers and wires that usually lead to a generator that is turned by spinning a turbine with falling water or steam superheated by nuclear fission or the burning of fossil fuels.  When the switch goes on the load on the generators increases by a bit more than we're using.  The steps required advances small and large over the decades in science and technology.   For example getting the of generation and transmission of electricity to work efficiently depends on an understanding of Maxwell's equations and a fair amount of math.  

 

We don't think about these things because we trust them. There's a solid bedrock of reliable knowledge in much of our technology even though we're not one hundred percent sure of the science.  Our trust in science is nearly universal even though some of us chose to deny certain aspects.  Global warming deniers and flat earthers have no problem using the Internet - computer mediated communication built on silicon based semiconductor technology, fiber optics and much more.   Their mistrust is often based on something in their personal value system that to first order may seem orthogonal to the scientific arguments.

 

Not many people have a good handle on how science is done and how it progresses.  Many of us had to memorize the steps in "the scientific process" in elementary school, but it turns out it's messy and there's no formal process.  In college you may have come across Karl Popper's notion of falsifiability and Thomas Kuhn’s paradigm shifts. Both of these models have been shown to be wrong.  The view among many scientists and philosophers of science is science is more or less makeshift, but produces reliable knowledge and tends towards self-correction and reliable knowledge over time.

 

A few years ago a few lectures by Naomi Oreskes at Princeton gave me the basis of something I'm more comfortable with even though it's not complete. She argues reliable knowledge is based on five factors:  method, evidence,  consensus, values and humility.  I won't go into these as each is a deep subject, suffice it to say that the last three are deeply social - something many "hard" scientists tend to have a difficult time admitting.  Science is deeply collaborative and these social aspects often determine what is worked on as well as how it, and the people who did it, are perceived. 

 

Although most people trust much of science, personal and group values can get in the way of trusting certain aspects as well as certain scientists.  We've witnessed this up close with the pandemic, global warming and evolution.  I worry that many scientists have made a mistake by hiding their values (that's changing with some of us) as well as separating science and technology.  The separation of science and technology was value based and began to become dominant after WWII. Somehow science was to be the pure pursuit of nature even though it's linked to technology at the hip.  Often technologists are well versed in the science underlying their work and some venture into applied science.  Scientists, particularly experimentalists, are by necessity amateur technologists.  I've done some technology and have a bit of a feel for it, but I'm certainly not skilled - I do much better on the science side.  I'm in as much awe of great technologists as I am of great scientists. 

 

A final point.  Who should you trust to do science?  If the light in your house keep going out when you plug the toaster in, it probably makes sense to call a licensed electrician.  When a pipe in your house bursts spewing out gallons per minute, you call a licensed plumber and not an electrician or dentist. A trip to the dentist and not the Ghostbusters is in order when you hit a cherry pit in a piece of pie and a tooth falls out.  And when you're thinking of the long term - say your children's lives - listening to experts on global warming makes sense while listening to Mobil-Exxon or the Farmer's Almanac doesn't.  In each of these areas there are mostly good players and a few bad ones. You find the good ones from the consensus of their community. 

 

flavors of augmented reality

Augmented reality has been with us for a long time.  Glasses and contact lenses turn the eye into a two element lens to correct issues with our eye's lens.  We use sunglasses to change the intensity and/or polarization of incoming light.  Some of these are responsive to changes in the scene around us.  Some of us wear hearing aids.  A few use assistive animals like seeing eye and epilepsy dogs. 

 

Some of these applications like glasses have fixed characteristics. Others like dogs can be highly adaptable.   Apple offers good example of computationally adaptive AR with AirPods and the cameras on iPhones and iPods.  The technical press tends to describe AR as overlaying a computational display - often information from the cloud keying on local state information like who you are, what you're interested in, your location, and so on.  

 

As it happens reality is much richer than what we experience with our senses.  Visible light is only a tiny segment of the electromagnetic spectrum and soundscapes are much richer. There can be any number of useful and recreational explorations into the larger reality - science does this all the time.  Wearable AR can open up wider videos into the incredible richness of reality itself.

 

It's been interesting watching Apple's shift in how they position their watch.  At first there seemed to be an assumption that it was a fashion accessory like a normal watch with some extra complications.  After a few generations it evolved into a health and safety wearable.  Initially Apple's visual AR device will probably offer simple visual overlays that you might see on a smartphone but with time I suspect it develop a strong health component that will be a major attraction.  People with serious glaucoma could get a view of the areas their eyes are missing.  As displays get better perhaps a visual AR wearable could replace glasses entirely matching your prescription and becoming a computational tool with the tricks we see in computational photography.  "zoom to the moving target and slow motion..." or "reduce glare from the water.."    It's easy to sit down and come up with a dozen ideas that aren't games.  The list gets even richer when you start linking in other sensors. 

 

We'll see wearable AR used in many modes, but I suggest the augmentation of local reality will be very important in ways we don't yet appreciate.  There are a lot of hurdles that make me think early devices will be crippled, but after a decade this could be a very rich area indeed.

 

 

 

 

 

looking back on long term focused change

Apple introduced two new laptops this week.  Fourteen and sixteen inch versions of the MacBook Pro.  On the surface they show a company responding to a certain class of users who value functionality over style.  A serious reversal from the days when Jony Ive dictated a minimalist approach.  Very nice laptops that happen to be extremely powerful. As fast as the most powerful Intel laptops with a much lower power consumption. It is likely these will run quietly most of the time - useful on video calls.   And while Intel has been almost stalled on increasing performance, Apples M chip series is only beginning its ramp.

 

I'm not a historian, but here's a rough sketch.  

 

  The Motorola 6502 was simple chip that retailed for about $25 in the mid 1970s.  The price made it popular with hobbyists.   Steve Wozniak used it in the Apple I and the commercially successful Apple II.  This started down on a long relationship with Motorola.  Beginning in the 80s Intel supplied the x86 chips used in IBM compatible PCs.  During the 80s Apple had moved to Motorola's 68x processors.  By the late 80s Motorola was falling behind.  Apple was in the unenviable position of being tied to a substandard processor.   Some in the company wanted to design their own processor, but Apple lacked the necessary resources.  Instead they turned to IBM which made fantastic silicon and was working on a reduced instruction set processor family (RISC) known as the PowerPC (PPC) 

 

I won't go into the RISC vs CISC wars of the 80s and 90s (CISC is complex instruction set) other than mentioning there were two competing processor architectures.   Intel's x86 and the Motorola 68x family were both CISC.  Apple was internally interested in the higher compute power per watt performance with possible with RISC.  Interested enough that they became part of a joint venture that changed the history of technology.

 

ARM was originally the Acorn RISC Machine - an English home computer the BBC was pushing.   Apple was the majority holder of a joint venture between Acorn, Apple and a chip maker called VLSI technology.  The company was headquartered in Cambridge, England and took the then novel approach of licensing their design rather than making chips.  To say this was successful is understatement.  Apple used ARM chips in the Apple Newton.  It was a failure and taken off the market when Steve Jobs returned to Apple, but the desire to have their own processor was there and a few changes forced by the market made it possible in the longer term. 

 

Apple introduced their first Power PC machine with an IBM processor in 1994.  It was fine as long as it was running software designed for the chip.  The problem was most software companies were more interested in supporting the fast growing Wintel platform.  Attempted to keep some market, Apple created an emulator that made the PPC act like it was a 68x processor.  It was a beautiful piece of software, but 68x programs ran slower on the PPC machines than on three year old 68x based machines.  Apple stayed alive, but nearly went out of business.  Then Steve Jobs returned with a much better operating system and - well - himself. 

 

By the early 2000s Apple emerged with some great industrial design and a growing number of PPC native programs.  Then came a tiny RISC machine called the iPod that only played music.  It gave them experience with integrated hardware, software and a service.  It may have also marked a point where Apple came out with something not only surprising, but cool.  But IBM was failing to keep the PPC relevant.  Apple needed to jump. This time the only choice was going back to the CISC x86 Intel processors.   Mac OSX, Apple's Unix based operating system, had been running on Intel chips for several years.  The software was improving quickly, but getting important developers write native applications was difficult.   Once again Apple built an emulator.   This time they had some internal experience with the process.  It was called Rosetta.   PPC instructions were converted to x86 instructions..  It wasn't perfect, but was efficient and good enough that the platform was growing again.  Growing enough to convince developers to write native software.  And  Apple was giving them the software creation tools to do it.

 

The pain of two major shifts and some interesting new products on the drawing board.  They needed their own silicon.  They purchased a small silicon design company and built it in the US and Israel.  It took years, but over time  the results have been remarkable  Systems on chips for the iPhone, iPad, AirPods, HomePods, the Apple Watch, and a variety of small support computers used in other devices like a pencil and a keyboard display.  All of these run versions of MacOS, use the same development tools,  and many are integrated into similar services.  

 

About five years ago Intel began to run out of steam.  Apple was working on its third huge transition for PC class machines. This time going from Intel x86 to their own M series ARM (RISC) based chips.  The first laptop was introduced last year.  The M1 was basically an iPad chip in a laptop. The operating system and a lot of Apple and third party software runs brilliantly on it.  The emulator runs native x86 programs about as fast as they ran on Apple's x86 laptops.  

 

That brings us to the announcement a few days ago - the M1 Max and M1 Max Pro.  (scroll down a bit for the chips) Both use the same ARM based design The larger Pro chip and has 57 billion transistors while the original 1985 ARM1 chip had just 25,000 transistors.  The ARM1 was made with 3 micron process (very roughly the distance between lines and spaces in the lithography) - that's 3,000 nanometers.  The M1 Max Pro uses a 5 nanometer process.  

 

Here's a relative size comparison.  ARM1 in red M1 Max Pro in blue. (A real M1 is about 20mm wide and the ARM1 is about 7mm) Look closely between the two and you may see a red one pixel dot. That's how big the ARM1 would be if it was made with the same process used in the newer chip.  

 

A feature of putting so much on a single chip is subcomponents can be directly connected on silicon.  It offers  greater performance and is more power efficient than putting data on a bus and shipping it around from chip to chip and then back again.  Such integration is very difficult  if you're selling a general purpose chip. Phone and PC makers need to differentiate their product and that usually means doing it with a mixture of chips and the software that binds them.  Apple doesn't suffer that restriction.  And, until Intel's architecture, there appears to be a lot of blue sky for performance improvement.  The real competition will probably come from other ARM chips, but Apple has a lead.  Here's some very early commentary from Anandtech.

 

While not many people will buy high-end laptops, they continue to buy the iPhone -  arguably one of the most popular consumer products ever made - along with a large supporting infrastructure of apps and services. And they make smart wireless headphones, smart speakers, smart watches, smart pencils and more.  All of this is based on the same core hardware and software architecture.   As a friend pointed out it's like the same company makes Ferraris, ebikes and everything in between using the same fundamental design philosophy and somehow making it work.   Not a perfect analogy as Apple has a much broader range.

 

A Moore's Law observation.  In 1985 the transistor count for all of the computers Apple sold in 1985 was about 25 bilion - less than half the count on a single M1 Max Pro chip. 

 

 

 

 

getting to clean enough

It's becoming clear that the SARS-CoV-2 virus will be around for a long time.  We're probably much closer to the beginning than the end.   Hotspots will shift and new variants arise so it makes sense to be ready to mitigate risks as much as possible.  Vaccinating the world should be a high priority along with next generation vaccines, better treatments, testing, high quality masks when the risk is high, etc. etc.  

 

Improving local air quality is low hanging fruit.  To first order that means high quality masks in hotspots along with fresh air.   Room air filtration and circulation can be a powerful tool.  As living animals we exhale carbon dioxide.  In pristine location, say a mountain top in Hawaii, you can measure the baseline concentration. Air is about 420 ppm (parts per million) carbon dioxide - a bit over 0.04%.  Enclosed spaces with people have higher concentrations.  You're breathing some of the air from other people.  If people are the only source, you can calculate the percent of the total air in the room that's exhaled:

        CO₂ concentration (ppm)        % of total air that is exhaled 

                    420                                                  0%

                    600                                                0.5%  

                    800                                                1.0%

                    1000                                              1.5%

                    2400                                               5.0%

 

With these numbers it was believed the risk is low for up to an hour if everyone was wearing a simple cloth mask and one person was infected with the alpha variant with carbon dioxide concentrations as high as 800 ppm.  The delta variant changes the threshold.   Now the one hour number is about 600 ppm with everyone wearing a surgical mask.¹  Of course the probability of an infected person being in the room is low if you're in an area where the infection rate is low.  

 

It would be good to know the concentrations where ever you go:   offices, classrooms, stores, theaters, taxis, airplanes etc.²  Consumer grade carbon dioxide meters can be purchased for $100 to $300.  If you're really interested I can make a recommendation, but I've only used a few.  We'll probably see a rapid improvement as these are going to be essential tools.  Japan is requiring them in many public places and school rooms.³  It's important to have an NDIR sensor (basically it's doing spectroscopy with an infrared laser to measure concentration  - there are many other techniques, but this is the cheapest with enough accuracy and repeatability).  These are accurate to about 50 ppm, so ignore the more exact looking reading and just round up to the next multiple of 50  - if it reads 537 just call it 550.    It takes about two minutes to get a stable reading and you'll want one that stores measurements.  The model I like talks to an iPhone app which gives you a nice chart of the day.   For businesses and schools it's a good way to check if the rooms are getting good airflow.   I saw one schoolroom that exceeded 3000 ppm when students were present. It turned out an air return duct was blocked - a thirty minute fix gave the students clean air again.

 

High carbon dioxide concentrations make people drowsy and sap cognitive abilities.  It hasn't been carefully studied, but readings over 1000 ppm can make you drowsy and perhaps a bit feeble minded.  One Army study suggests 800 ppm should be a warning level.  Half-jokingly I told a superintendent that he could justify the cost of measurement though improved test scores.  It turned out that's what sold him.  Maybe it's a way to upgrade the collective intellectual capacity of an office.  Another benefit is a possible reduction in airborne diseases like the flu.  

 

You can't always open windows and doors to get a solid draft, but HVAC systems can often have their fan settings increased and room vents adjusted. High quality filters can capture viruses along with other particulate like some from a fire.  MERV-13 is a sweet spot for price,  the ability to snare virus sized particles and not requiring more powerful fans.  And you can buy or build portable air cleaners.

 

The hot ticket for rolling your own is a very simple design known as the Corsi-Rosenthal cube.  Here's the public domain diagram we used to build 84 of them for about $5,000  (the cost shown in the drawing doesn't involve much shopping around).  We used the cardboard from the shipping boxes the fans came in.  The shroud is very important.  Square corners disturb the airflow and can drop the unit's efficiency by about a third. A normal sized classroom for 30 to 40 students probably needs two units.  Keep them away from walls, doors,  and openable windows.  The filters will probably last the school year if you turn them off when people aren't in the room.  Most of the classrooms are showing readings under 600 ppm with these and the school's HVAC system fans all on high.  The boxes make a big difference.  Commercial air cleaners with good filters probably make more sense in offices and schools if they want to go long term, but 600 cfpm MERV-13 filters are about $500 and in short supply these days.   Like carbon dioxide meters I suspect we'll see some movement on air filter and fan design. 

 

Some learnings:

Duct tape is frustrating!

Schools have mountains of duct tape.

Eighth graders are the perfect people to enlist if you want to build a lot of them.  Eighth grade girls if you want them to be semi-presentable.

_________

¹ These are rule of thumb numbers based on empirical evidence.  But it's complex with many confounding factors. 

² A closed car can be spectacularly high. I sat in my car for fifteen minutes with one other person and recorded 3800 ppm!  You can drop this by opening the windows.  Opening them diagonally makes a lot of sense for creating airflow.  Airliners have good general circulation, but a given row can be bad.  A flight is probably much safer than a half hour Uber ride if the driver has the windows up.

³ People are already taking measurements in gyms, restaurants, etc and putting them online with locations and business names. It's ad hoc and not very standardized, but there are over 100 locations in NYC the last time I checked.  It makes much more sense for a business to do their air handling homework and post numbers in their establishment as well as their website.  Hopefully at some point a respectable aggregator will step in.

 

                                      

sorting out what a product announcement means to you

Our neighbor left the box with my mother.  He was an Air Force Captain taken with building things of one kind or another.  During my Junior year in high school it was building electronic kits.  Back in the day that meant anything from Heathkit.  The company produced well-designed stereo components, oscilloscopes, an analog computer (long story, but my high school had one), test equipment, and amateur radio gear.  If you knew how to solder they were almost idiot-proof and you could repair them yourself when they broke.  A few of his old projects somehow made it to me.

 

It was a Heathkit AA-40 - a 40 watt per channel class A tube amplifier.  Unlike many of his gifts it still worked. The problem was I didn't have a turntable or speakers.  We had a family stereo, but touching it would have been socially dangerous.  I found an old turntable and a single very not very good speaker.  Anything moderately good was out of the question. Sometimes it's useful if you can't afford something.

 

I had read that the mass of the driven element, a speaker cone, was important.  Low mass meant high acceleration for a given force.  It made sense.  There were exotic electrostatic speakers with even lower masses than a cone.  Supposedly they sounded great, but had some technical issues.   It started me wondering if I could go to an even lower driven mass. 

 

A feature or flaw about me is I'm usually more interested in how something works than what it does or what it might do for me.  I thought ham radio would be exciting.  It turns out it was mostly people telling you how good your signal was, the weather and a few other boring things.  On the other hand how radio waves propagated through the atmosphere was fascinating and still is.  Faced with needing a speaker I was drawn to the basics.  It was just turning an electrical signal into a mechanical motion which would create a string of pressure differences in the air.  Speaker coils, magnets and paper cones.  On the other hand if I could make a plasma dance... 

 

I used a blow torch with a wick made out of asbestos (I know) that brought a salt solution into the flame.  Of course there was a background noise and it was a serious fire hazard, but you can't have everything at once.  The amplifier's output went into a high voltage transformer from a junked TV and into two electrodes in the flame.   It worked! The flame moved  in time to the music which was sort of identifiable as music.  It sounded terrible with the hiss and wasn't exactly safe for indoor use. But I've never been an audiophile, so it was an achievement in my book.

 

The same with a lot of technology.  It's deeply fascinating, but how chips are made and how semiconductors work seems more interesting than how I use them. And how people use technology is more interesting than how I use it.   (Sociology is way beyond me.)   There's a lot I'm interested in, but when it comes to personal adoption I tend to be in the middle and sometimes the trailing edge.  I'll buy something new,  like the first iPod or iPhone, and replace it every year until it does what seems useful.  Then I keep it until it fails or, like my old MacBook Pro, has a maddening keyboard.

 

I'm mostly in Apple's ecosystem so smartphone means iPhone to me. As time goes on I've made an effort to rely on it less and less.  It packs enough very useful features that I wouldn't go back to a pre-computer wireless phone, but my four year old phone is currently in a wait until it fails mode.

 

That said I follow Apple developer's conferences and product announcements.  The current iPhone 13 has a remarkable set of photographic and video capabilities.  Computational photography gets better every year and is now at stun level.   Apple is using the processor, graphics processor and machine learning hardware at the same time in some of the modes.   It's astounding.  If you're a serious photographer like Om or Bryan, you probably need one and have already ordered.  The device seems mature at this point.  They didn't make a big deal of it being faster, but rather concentrated on battery life.  Pro tip - mature portable electronics that check all of the feature boxes focus on battery life.  In the end user experience wins.

 

I'm not a photographer so a new iPhone would be overkill.  Maybe in a year what I have now will be unusable and I'll have something new.  How these things work and how they're built is the exciting part.  I would not have predicted some of the video features on the new phone. 

 

Horace Dediu has one of his always insightful pieces on the importance of the new iPhone.  In my case I'm probably a trailing edge user at this point - different from the much larger group Apple is addressing as they reinvent what the iPhone is useful for.  He's worth following if you have an interest in on person computational power and the micromobility revolution.

 

On the other hand Om may have nailed the really important product launch this season.  Then again, he offers an excellent iPhone 13 Pro review. 

 

 

 

a shot echoed in the dark

   Our guide, the Director of Development for The Cleveland Orchestra, noted how difficult it was to find matching marble for the lavatories.   There were only two of us and we wanted to set up in the main hall, but impressions must be made and little was being spared in the big three year remodeling job. 

 

Cleveland's Severance Hall is a remarkable place.  A odd mash-up of Art Deco and Egyptian Revival architecture, it was finished during the Great Depression and became home to The Cleveland Orchestra.  Like many symphony halls the acoustics were bad boarding on terrible.  Remodeling a few decades later partly fixed the problem, but in addition to rendering the pipe organ unusable,  was architecturally "wrong."  The work underway when we visited would address all of those issues and make the space one of the best concert halls in the world. 

 

Our company was doing quite a bit with digital music at the time.  There was a relationship with the Rock and Roll Hall of Fame and another with the Oberlin Conservatory.  Two of us who were doing much of the Oberlin work developed a relationship with The Cleveland Orchestra and Telarc Records on the side.¹  At the same time work on sound field reproduction was a serious research topic.

 

The idea behind sound field reproduction sounds simple enough. If you've ever been around live music - or even in a recording studio - you've probably noticed your home equipment can't begin to reproduce the acoustic experience.  The problem stems from the fact that the wavelengths of the sounds we hear range over three orders of magnitude and much of it is similar in size to musicians, audience members, seats, curtains, the room itself, etc etc.  These sounds are reflected, refracted and absorbed.  Moving anything causes a change.  It's a difficult problem that the music industry and Hollywood would love to see solved.  Plus it's an interesting problem!

 

The approach we were using had a microphone array on a tripod.  One up, one down and an odd number between them in the same plane as the floor.  Severance was undergoing acoustic tuning and we were going to set up the array to record some music to compare it with other techniques.

 

We were left alone in the open hall. It was very quiet so I did the obvious thing and clapped my hands once.  There was a lovely echo coming from everywhere at slightly different times.   If we recorded an even better "clap" - an impulse function - we could mathematically play with it and create a signature of the room.²  Armed with this we could have some fun.  We needed to create a good enough impulse.

 

Severance Hall is on the grounds of Case Western Reserve University - a lovely area with good restaurants and a lot of art and music.  (if you ever stay in the area get a room in Glidden House - fantastic little hotel).  I figured the school probably had an athletic department and quickly found a track coach.  I was able to talk him into lending me a starter's pistol.

 

Later that night in the darkened hall a shot rang out - only to be captured digitally.  Then a few more just to make sure there was enough.

 

Back at the Labs we had a special acoustically isolated room - an acoustically neutral room (these are rare and not cheap!)   Using the same microphone array that was used in Severance Hall we recorded some live music with musicians in the area.  The music was convolved with Severance Hall's signature and then mixed down to six channels for playback in the room.  

 

It was fairly convincing..  close your eyes and it really felt like the place the shot rang out in the great hall.   Of course you can do better, but it was a great excuse to have a bit of fun.

 

__________

¹ Over the years I’d spent some time worrying about image and sound quality. At one point I thought better was - well - better. My epiphany came in the a perfectly restored 66 red Mustang. It was near Cleveland with the head recording engineer from Telarc Records and a seriously good musician from the Oberlin Conservatory. We were talking about where music reproduction might go with sound field reconstruction and dramatically more information than CDs could provide when a favorite Beatles tune came up on the 8 track (gasp! - it *was* an authentically restoration). The volume came up and the two of them were singing along to the music in pure delight. There is something transcendent about the music - even with awful reproduction in that noisy environment. Portable music players with cheap headphones would be good enough for most. As long as there's a personal touchstone.

²  take its Fourier Transform.