omenti

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.

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...  

 

 

power different

Recently a friend sent a piece on an energy harvesting device that coverts some of your body's waste heat into electricity.  The description was sparse, but it mentioned the average person produces about one hundred watts of waste heat and went on to say that is enough to power a laptop.  

 

umm..  Both true, but there are some problems ...

 

The average adult metabolizes about 100 watts on average to stay alive.  That's about the same as eating 2000 calories of food a day.   The average adult has about 1.7 square meters of skin area.¹  This means we need to get rid of about 0.006 watts per square centimeter of skin area.  Six milliwatts of power per square centimeter.  The photo of the device showed a ring like affair with some fins - maybe two square centimeters of radiator area.  Let's round that to about ten milliwatts for the device - hardly enough to deal with a laptop, which are on the order of 20 watts or even a smartphone which are a few watts.  That assumes all of the waste heat can be harvested with one hundred percent efficiency.  Here things begin to go down hill quickly.

 

A thermoelectric converter on human skin has a theoretical efficiency of about 5% at room temperature.²  This reduces the six milliwatts per square centimeter down to 0.3 mw/cm².  Even if you covered your entire body, you'd only harvest five watts and you'd be shivering.   And that's unrealistically optimistic as these devices rarely have more than single digit efficiencies on top of their thermal efficiency in this temperature range.  Even optimistically we're down to about 0.03 mw/cm² or 30 microwatts/cm².  Something like an armband might have 100 cm² giving us 3 milliwatts.

 

This isn't reason to abandon hope.  There are hardware devices with sub-milliwatt power requirements. Small energy harvesting devices that harvest mechanical or solar energy also exist and make it practical to put tiny sensors with tiny transmitters nearly anywhere as long as your receiver is nearby. The micro part of the Internet of Things (which has its own issues).  It turns out this is a rich area for college engineering projects.

 

But what about larger power demands where it's inconvenient to change batteries?  Spacecraft that travel past the orbit of Mars generally rely on radioisotope thermoelectric generators (RTGs) because the Sun is too dim to make solar power practical.  An RTG puts a thermoelectric converter on something hot - a radioactive material that decays rapidly.  Ideally it's an alpha emitter so you don't need heavy shielding.  There are a number of candidates, but Plutonium-238 (Pu-238) is the most common American choice with a half life of about 88 years. Not only do these generators produce electricity, the extra heat is used to warm the spacecraft's warm.   The current generation of Martian rover is RTG powered. 

 

There are a number of RTG stories.³  I don't want to go on forever, but the nuclear powered pacemaker and artificial heart are among the more interesting.  

 

A problem with early pacemakers was longevity. Batteries had to be replaced every eighteen months or so necessitating expensive and risky surgery.  In the late 60s and early 70s two types of tiny radioisotope generators were manufactured for use by several pacemaker manufacturers. They had enough shielding to be very safe and would last longer than even very young patients.  They were also very cost effective and a few thousand patients received them. Then, in the mid 70s, the practice suddenly halted.   The worry was devices might not be removed before cremation from patients who had died.  This would destroy the shielding and turn an area in and around the crematorium into a radioactive hot zone requiring evacuation and a very expensive cleanup.  

 

The radioactive heart implant never made it into a patient.  To make enough power to run the heart, the RTG generated about 50 watts of waste heat adding to a normal person's 100 watts.  It wouldn't be bad if it could be spread over a skin sized area, but that would be impractical.  It would be like holding an incandescent light bulb.   One of those interesting ideas that you wonder about afterwards...

_________

¹ The approximation medical researchers usually use is from Mosteller:  (height[cm] * weight[kg]/3600)^0.5  a

² The theoretical maximum efficiency of a heat engine is 1 - Tc/Th  where Te is the temperature of the environment - the air around the device in this case - and Th is the temperature of the radiator - the skin temperature.  We have to use an absolute temperate scale so Th = 310°K and Tc ~ 295°K.  So about 4.8% efficient.. let's call it 5, although it is probably half that with poor coupling to the skin and air. 

³ One could go on for a long time .. the CIA's RTG in the Himalayas is particularly interesting.  And then there's the Apollo 13 RTG that required last minute maneuvers as the limping spacecraft approached the Earth.   The very hot RTG is somewhere on the floor of the Pacific.

 

a meltdown between two brownies

You need to read Om’s blog post Why iPhone is today’s Kodak Brownie Camera  It reminded me of my home-brew digital camera about 35 years ago (the Meltdown the ferret photo is in this post - probably the first digital image of a ferret).   

 

 

Digital photography - at least how we usually think of photography (more on that later) - was invented in 1975 by Steve Sasson at Kodak.  (a fun NY Times piece)  Charged coupled devices (CCDs) used to capture the image, had been invented at Bell Labs a few years earlier.  Sasson used one made by Fairchild for his experiments.  I had read a bit about digital cameras when I built mine, but decided to used a modified DRAM memory chip because I could get one for nothing and it seemed like a reasonable thing to try.  It was just that - fooling around with some hardware and writing a bit of software for fun.  The fact that it captured my only record of my ferret Meltdown made it special.

 

 

But there’s another form of digital image making.  Experimental particle physics people moved from detecting events with regular photography (bubble chambers and film emulsions) to electronic counters.  Around 1968 the multiwire proportional chamber revolutionized the field and set the stage for dramatic discoveries that lead to the Standard Model - still the best description of three of the four fundamental forces.  A MWPC consists of many planes of parallel wires.  They’re assembled in a chamber filled with a gas that ionizes when a charged particle flies by.  The wire closest to the passing particle detects the event and a signal is read out. These arrays are arranged at right angles in tightly spaced pairs so it’s possible to calculate a position in two coordinates.  As the particle passes through the chamber its x and y position is registered along its track.  A computer calculates a trajectory for each particle and all of the particles that registered form a 3d image of the event.  This information is then processed to reveal the physics of the event.   This type of photography has become more sophisticated and MWPCs have largely been replaced by more capable detectors, but it's still the same idea - just a fancy camera.    The people  who use these exotic cameras use their smartphones like everyone else for all kinds of personal images. 

 

 

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.

 

 

Om points out there is a market for high end photography.  Perhaps the real distinction is high end photography is more of a verb than a noun.  You do it to learn how to see images as much as to capture them.   Hopefully it will never go out of fashion.

 

you're here because dinosaurs didn't have good telescopes

Sixty six million years ago - the end of the Cretaceous period  - an asteroid or comet struck the Earth near what is now Chicxulub, Mexico creating a crater 150 kilometers in diameter.  Huge tsunamis that rose hundreds of feet as they approached coastlines.  Worse, firestorms swept the planet and the oceans underwent a sudden and deep acidification.  Food chains collapsed on land and in the oceans and with them three quarters of plant and animal species vanished.  

Arguably it was a bad day.

If the non-avian dinosaurs only had evolved larger brains perhaps they would have made it to the point where they had good astronomy and a good enough space program.   But nature keeps moving on and the massive change allowed other lifeforms to evolve including us.  In retrospect it was a great day for the human race.

 

Could it happen again?  That one's easy -  100 percent probability.  Fortunately we're at the point where we have astronomy and a space program so it makes sense to think about risk and mitigation efforts.   

 

In 1994 a comet called Shoemaker-Levy 9 broke into 21 major pieces and struck Jupiter.  It had been captured by Jupiter's gravity and had been orbiting the planet for about three decades it put on a show that would have devastated life on Earth.

 

An Earth strike would be different and Jupiter's large size makes it a more likely target it did ring alarms and people started thinking about the probability of something big enough to do serious damage hitting the Earth as well as what could be done about it.  After all - we had telescopes to figure out likelihoods and rockets to do something about it. 

 

On the 1^st of July, 1770 we came very close to a major extinction event - one that probably would have included humanity among the erased.  Lexell's comet came with six times the distance between the Earth and the Moon. Cosmically speaking that's a near miss.  New comets tend to appear anywhere between a few months to a year before they could be dangerous.  But there's much more than just comets out there. 

 

NEOs - Near Earth Objects - are comets or asteroids that come close to or pass through Earth's orbit.   They range in size from a few meters to several kilometers.  Small ones are common and tend to fragment or disintegrate leaving only small pieces for collectors and scientists.  Moving up the size scale you pass through city killers to objects capable of global devastation.  Fortunately the big ones are fairly easy to spot, but over ninety percent of the estimated city killers have yet to be cataloged.

 

A program to funding the construction and operation of new survey telescopes along with retrofitting existing observatories was kicked off about ten years ago with the US and EU taking part.  It's relatively inexpensive and has made some progress, but the Trump Administration cut funding.  

 

So what can you do?  With enough advance warning you can evacuate regions for objects in the city killer size range.  Moving up the size scale means using rockets to intercept the threatening NEO.  What to do with it is non-trivial and depends a lot on its composition and size.  That's an interesting subject for a future post if there's interest (hint: you probably don't want to nuke it) , but an important step would be expanding missions to asteroids of various sizes to learn about their makeup.  In addition to insurance there are technical and scientific benefits that are probably justification enough.  

 

Perhaps it would help us think about preparation and mitigation - the next pandemic and global warming will both make their presence known with much higher probabilities in the next few decades.  

 

 

 

 

where simple beats "ai"

minipost

A friend complained about his new rice cooker.  It's a very expensive model with programmable features and claimed to use "ai" for "perfectly cooked rice" every time.  After a dozen or so attempts he called their help line and spent a half hour using their smartphone app that talked to the cooker.  It passed the diagnostics with flying colors.  He isn't happy.  

 

Simple rice cookers tend to work well every time.  They rely on two bits of physics that give clear signals.  The first is how water responds as you heat it.  The energy needed to raise the temperature of liquid water by one degree is very nearly the same from room temperature until it's right at the boiling point.  Adding more heat at the boiling point just turns the water into water vapor - the remaining liquid water stays at 100°C.  

 

The next clever bit was discovered by Pierre Curie who probably never thought of its rice cooker use. 

 

The cooker I use has a spring at the bottom of the pot and a strong permanent magnet.  You put rice and water into a smaller cooking pot and push it down a bit until the magnet attracts and grabs a piece of special metal.   Then the heating element engages and cooking begins. The rice is cooked as the water heats and continues to cook as it boils.  The rice temperature stays below 100°C until just enough of the water starts boiling.  When most of the water has boiled away the rice temperature starts rising again.  Now the discover of Madame Curie's husband takes over.  At around about 105° C, the Curie temperature of the metal, the metal is no longer attracted by the magnet.¹  The spring pushes up and turns off the heating element and a power light.  On mine it is also connected to a mechanical bell and turns off a power light.  The rice is always great.

 

I looked at a repair takedown of an expensive rice cooker.  The construction was better, but it was complex with a microprocessor, control panel, barometer, humidity sensor, thermometer and Bluetooth chip (they have a smartphone app:-). Presumably it has some sort of table that rice is perfectly cooked when all of those signals reach a certain values, although it could be more complex.   I'll stick with simple.

__________

¹ Magnets lose their magnetism when heated at a specific temperature called the Curie Point.  In this case the permanent magnet stays magnetic at 105° C, but the special metal used here suddenly loses its ability to be attracted by a magnet.

 

frogs, pots of water and the slow application of heat

A few weeks ago Om posted a piece on Apple's new laptop based on their M1 chip.  It's one of those huge transitions that gives Apple a much higher starting point  for desktop and laptop machines - machines that are still very important to many of us. They've been working on this for at least ten years as part of their smartphone silicon effort. People like Horace Dediu and Om (and even a non-technologist like me) have noted the progression of Apple silicon and wondered if it would be deadly to Intel.  For me the biggest surprise has been the software effort - writing was all over the place for on the silicon side. 

 

Zoom's emergence represents a pot that had been slowly warming for decades coming to a sudden boil with pandemic-fueled heat.  It's frustrating with a terrible UX and UI, can be iffy on highly asymmetrical Internet connections that are slow upstream (cable modems for example), causes enormous frustration for many, but it's better than other tools and works well enough.  Last week I described it as the modern equivalent of the <blink> markup in html during the early days of web browsers like Mosaic.  People think it's cool at the time, but it will be laughably primitive down the road.   

 

Remote video tools will get better and may change some habits. At the same time others are recognizing the importance of face to face. One university I work with just completed a survey that found 0% of 1600 students said they'd prefer in-class instruction to remote leaning when the pandemic quiets down.  Already there's a lot of experimentation on campuses and in some businesses.  An animation company saw productivity crater and is working on a better than Zoom suite of tools for internal use. The university I mentioned has found messaging apps like Discord excel in spaces that Zoom handles poorly.  And perhaps we'll get better Internet connectivity.  Price to performance in the US is abysmal, 5G is a largely marketing joke, cable modems are too asymmetrical (upstream is slow) to support serious video conferencing, and the digital divide has widened the already huge education gap.  There's a lot to fix.  It's like cycling - you need to sort out infrastructure and culture along with adding bikes.  

 

I'm confident tool improvements will come but serious leaps need to be taken and I don't have great confidence in the major players.  What I'm more worried about, at least in the US and Canada, is infrastructure. A friend is moving from Colorado to North Carolina and needs a very solid Internet connection.  The only advice I could give was to find cities that offered good fiber connections that we're from telcos.  That mostly narrowed it down to Ting, which left only a few cities. The movement of people from cities to rural and suburban areas is constrained by many forces - this is one. 

 

On to something else..

 

I've argued that virtual reality wasn't very important and augmented reality meant much more than projecting information in your field of view - and that Apple had just introduced their first AR product. 

 

In a way glasses are AR devices - they help you see more than you normally would. The same for microscopes, telescopes, stethoscopes, I have built bat detectors that let me augment my world by adding a bit of theirs, ... the list is long.  But back to my comment about Apple.   I have to admit I was wrong.  Apple's first AR product was the Apple watch, although they didn't know it at the time.  At first it was more of a fashion statement with a weird assortment of apps.  After a few years they learned what it was for.  People saw it as something for improving their health and fitness. Exercise, heart monitoring, and even the state of your body. Jutta has an app that interfaces with other hardware for diabetes management.  We're talking about life altering AR.   The area is growing rapidly and we won't even think of it as AR because we're used to its Hollywood manifestation.  Of course Alexa, Siri and other voice driven interfaces are AR.  They augment our local information space.  Apple's EarPods are just a portal you wear.  There's still a place to visual AR, but the pot's already boiling.  AR is here now.

 

Of course we should think about how these things fit into our lives. That's a serious area I'm not terribly confident about - at least if tech is making the design choices.