omenti

some really big changes

event                    species eliminated     million years ago        cause(s)

End-Ordovician                       85%                 444                     global cooling  

Late Devonian                    70-80%          372-359                    multiple events, low O₂ in oceans    

End-Permian                      90-95%                 252                     volcanism

End-Triassic                            75%                  201                     volcanism

Cretaceious-Paleogene           75%                   66                      impact event, volcanism?                                              

 

In the late 70s a group led by Luis Alvarez found a very thin layer of an element that shouldn't be there in locations all over the Earth.  Iridium is very rare on the Earth, but common in meteorites and probably asteroids.  The layer was found in enough places that could be accurately dated.  Dinosaurs fossils were abundant below the layer and non-existent above it.  About three quarters of the species on Earth had vanished in a short amount of time.

 

It remained an interesting hypothesis until about a decade later when a 200 kilometer wide crater was mostly in the Gulf of Mexico and just happened to date to the end of the Cretaceious - about 66 million years ago.  It looked like the smoking gun, but any remnants of the asteroid were under layers and layers and layers of limestone.  But a few years ago what may just be the smoking gun was found.  The area around the crater has a large amount of high sulfur evaporate sedimentary rock. Drilling deep into the crater the sulfur-rich rock is mostly missing.  When the asteroid slammed into the earth so much energy was liberated that layers of this rock were vaporized.  In the atmosphere they combined with water and surrounded the Earth with a thick dark cloud layer that dramatically dropped the average temperature of the Earth.  For something like ten to twenty years temperatures on the land were near or below freezing. Not good if you're a plant. Not good if you're cold blooded and/or have a large enough body mass to require a lot of food.   

 

At the same time a large amount of carbon dioxide was emitted.  This probably helped preventing the temperature from going way below freezing, but it acidified the oceans killing a lot of marine life.   Land and ocean-based food chains were interrupted.  

 

The Chicxulub impact event is very compelling, but is it the whole story?

 

Perhaps not.

 

Around the same time, perhaps a few hundred thousand years earlier, something dramatic was underway in what is now Western India.  Four major volcanic events produced enormous lava flows collectively known as the Deccan Traps.  About a million cubic kilometers it would be enough to cover the US with about 120 meters of lava. Could it have been part of the extinction event?  After all, two of the major extinction events were volcanic and this one was approximately huge. (over three hundred times larger than the Yellowstone event)

 

Over twenty or thirty thousand years enough carbon dioxide was released to dramatically increase the Earth's temperature.  There's a growing consensus that it was part of the extinction event, although there's a lot of academic debate as to how important it was . Was life weakened by this increase and then finished off by the asteroid, or was most of the damage done by the eruptions?  A lot of interesting questions are being worked on.

 

The last extinction is relevant because at least one part of it was quick.  We're now at the beginning what appears to be the sixth extinction event.  The one we're causing and perhaps an extensional threat to humanity  It's also shaping up to be a very swift event. Learning how the atmosphere and oceans respond to such events is important. 

__________

Some of you know I've been trying to do something about global warning for about twenty years.  I've made another major change in approach.  I've never expected a major impact, but my first two approaches of education and storytelling have been failures.  I've moved on to targeted conversation.  Well beyond my pay grade, but in retrospect it appears to involve less titling at windmills.

 

 

on good design for those who need it

Olympian Sarah said she is more impressed by the achievements of Paralympians than Olympians.  She loves events like running with a guide and is particularly taken with goalball.  Goalball was invented after WWII for the blind.  The ball has two bells and the athletes have to use their sense of hearing to sort out where the ball is along with the other players.  It's stunning to watch.  (The first match is the gold medal match between the US and Turkey.)

There's a lot of interesting design in the Paralympics.  Sometimes the type of game, sometimes mechanical devices like special wheelchairs, and perhaps most important is a classification system to keep competition fair,  The amount of thinking that has gone into this puts many conventional sports to shame.  If you haven't watched any of the events go back and marvel at a few.  

 

Building proper access has been an uphill battle and people still fight against the Disabilities Act claiming it's "too expensive" or "just not worth it."  Getting the design right is a journey of its own.  A book that may change how you think about the built world is What Can a Body Do? by Sara Hendren. Solid recommendation!  This kind of design goes beyond physical affiances involving politics, law and sociology with the book addressing that and more.  The Paralympics are a shining example of it being done right in a limited area. 

 

This may seem a bit off topic, but I'd claim otherwise.  I've learned a lot from areas far from what I do.  Thinking about beach volleyball  led to a useful technique for studying neutron stars.   Get interested in something very different and you just might find interesting connections to something else.  Thinking about those with challenges is a rich area and probably useful for even non-designers to spend some time on.  It's a target-rich environment. 

 

 

low distortion rearview mirrors

 

History Does Not Repeat Itself, But It Rhymes

      -  Mark Twain

Except it wasn't him.  

His clever and prolific writing made people assume he said it even though he never did.  It turns out it first appears around 1970 in a poem by a Canadian artist named Robert Colombo.  When asked if he knew where it was from Colombo couldn't recall other than he might have seen it in a literary section of the New York Times a few years earlier.  In fact it appears with and without attribution several times around the time of Colombo's poem in the early 70s.   That said, a hundred years from now people will still think Twain said it.

 

The process of science is much messier than the simple order kids learn in school.   There are too many dependancies to list.  A few philosophers of science  - notably Karl Popper and Thomas Kuhn - have tried to describe how scientific revolutions and change happens.  The how, where and why of scientific change.  Kuhn and Popper are somewhat at odds.  Kuhn's ideas were popularized and are still taught as how scientific revolutions happen.  It turns out that both of the frameworks are deeply flawed and have fallen from favor with serious students of the history and philosophy of science.  I came to it late, but I'm more a fan of an earlier step - trying to understand some of the history of science. 

 

Unfortunately the history of science is often neglected in scientific training.  Students are told a few selective stories from the great revolutionaries without much context.  Experiments, theories and techniques are described with little background.  The struggle and small steps forward and backward are  missing.  The world seems much too messy when you start doing real science on your own.  (this is probably true in many fields!)

 

One gets bits and pieces of local history from the last generation or two in their subfield.  This can be very powerful. I learned a lot about the development of the atomic bomb as some of the people I studied with were parts of the Manhattan Project.  You need to learn the importance of failure as well as hunches and the need to distrust your own work.  

 

The history of science, like the history of art or music,  is a story of the development of ideas that can be appreciated by non-specialists.   There are some wonderful books out there.  The trigger for this post was one of them:  Einstein's Fridge by Paul Sen.  I know the technical area well, but have big holes in my understanding of how all of this came about.  If you can follow articles in the New York Times science section, you'll learn a lot of what the physics is saying without the math and how it changed the world.  He gives a very simple, but accurate, description of entropy and has the best description of photosynthesis I've seen that doesn't get into biochemistry.  The historical motivations make it come alive.  I'm stealing some of his clear descriptions.

 

Most of this is probably true in many other fields.  About twenty years ago a friend invited me to dinner with Maurice Wilkes - his grand advisor.  Even though Maurice was in his late eighties the discussion went on late into the night and continued on two more occasions. I'm not a computer scientist or engineer, but Maurice is a physicist who happened to invent a good deal of the fundamentals of computing that's still in use.  Hearing him talk about the early history and the connections to our shared background made it all come alive.  The problems computers had to solve as well as the nuts and bolts of designing one - provided a wonderfully rich learning experience.  There was this hint of how the great mind of this humble person worked. A good history book can provide that kind of experience.

 

 

on fundamental change

 

Ludwig Boltzman, who spent much of his life studying statistical mechanics, died in 1906, by his own hand. Paul Ehrenfest, carrying on the work, died similarly in 1933. Now it is our turn to study statistical mechanics. Perhaps it will be wise to approach the subject cautiously.

It's not uncommon for a professor to quote the first paragraph of States of Matter by D.L. Goodstein on the first day of an undergrad statistical mechanics course.  Statistical mechanics is an outgrowth of the study of thermodynamics which had become a major intellectual effort attempting to understand heat engines in the 19^th century.  You can derive the results of thermodynamics from it and it led to much deeper explorations including the beginnings of quantum theory.  It's also concerned with entropy.    Entropy is at the heart of understanding change.  It's deep enough to be tightly connected with why time only goes forward and what cause and effect are.  Popular definitions aren't accurate. It isn't the tendency to disorder and it isn't the entropy computer scientists talk about (although Shannon's entropy is an exceptionally important tool for thinking about information). 

 

Unfortunately the fundamental concept of entropy is a bit abstract.  xkcd notes a problem common in science and undoubtedly many other places.  I'm frequently guilty, but I started to put together a post on the difference between entropy and complexity and why increasing entropy doesn't imply increasing complexity that doesn't involve math.  I found myself sketching pictures and wishing they were animated.  Then I remembered Sean Carroll did a series of very short YouTube videos with Henry Reich creating the animations as part of Henry's Minute Physics series.  They're wonderful!

 

The third video: Where does complexity come from?,  gets at the core of the entropy and complexity and why entropy isn't disorder.  It works as a stand-alone, but I recommend watching all five in order.  They achieve a good balance of getting the basic concepts across without any danger of anyone committing suicide.

 

Sean begins with why doesn't time go backwards and covers a fair deal of what the Second Law of Thermodynamics implies.  Things like cause and effect, the origin of complexity and even how life can exist.

 

Some deep and sexy physics without the math.

 

 

silver linings?

The pandemic has been responsible for an enormous amount of pain, agony and death.  While we're not out of the woods and won't be for the foreseeable future, a few potentially positive change has been made more likely. It's easy to make a long long and think about some more deeply, but for now a short list.

 

° mRNA vaccines have been under development for over two decades.  Their value has been shown in the most dramatic fashion.  Expect many more - some for conditions that have been very difficult or impossible to treat.

° American contributions to a worldwide network of outbreak observatories were killed by the Trump administration. Finding the next outbreak early enough to contain it requires this kind of work.  We've been lucky and able to catch and contain a few recent candidates early.   Finally there's  a large amount of interest and it's likely to happen.

° We saw an existence proof that parts of nature repair quickly when human impact is reduced.  Unfortunately most of these improvements have disappeared, but many of us have seen them and perhaps some of us will be better motivated to create change.

° Many cities tasted alternative transportation and street use.  It seems to be sticking in some areas. The automobile doesn't belong in cities for a variety of reasons.  Side note:  Electric cars are insufficient - the transportation system needs serious reworking.

° It appears that part of the reduction on business travel may be permanent. 

° A huge social experiment is underway to see what kinds of work can be done remotely.

° Likewise a similar social experiment is underway on remote education.  This is a very complex problem involving much more than what is normally thought of as education.

° Serious work is underway on indoor air quality. This has positive implications beyond airborne viral transmission.

° It's still a way off, but more thought is being given to single payer insurance.

° Massive universal basic income experiments are underway worldwide.

° There are indications young people are spending less time connecting online.

° There's  renewed interest in good science communication.

° A few have been afforded the opportunity to create personal change.  This may prove to be one of the most interesting impacts.

There's much more than this - I wrote these down in a couple of minutes.  I encourage you to make your own lists. Some of these are rich topics for exploration.

 

 

very light narrative structures

I first heard about Norwegian Slow TV a decade after it began.  I watch a half hour of one of the rail trips. It didn't do anything for me.  Other than hearing about other hits like chopping wood and knitting, I almost forgot about it.  Two months into the pandemic I found my watching a semi-live train trip across Norway.  Much of the  scenery was similar to where I grew up and I found myself watching.   It wasn't long until I found myself daydreaming, creating my own narrative to match the flowing images.  Two hour later I stopped a dream-like story in my head.  

 

About four in the morning the next day I was jolted out of bed with an interesting approach to some physics that I had abandoned months before due to lack of process.    Having your mind work on something when you're not working on it is well known.  I suspect the neural connects I had was making in the narrative I was writing in my imagination had a good deal to do with it.   

 

This morning I caught an episode of Invisibilia that dives into the subject.  Recommended if you have an interest in narrative in any form.  Slow TV is an hours or days long TV show without plot, characters, or tension.  How Norwegians responded as a shared experience is the most fascinating part

I've done a bit of work in remote audio ambiances.   A few created serendipity.  Here's an excerpt from an old post on one:

 

5:25 am - excellent!

 

I brush the last of the snow from my coat and switch on the lights before taking my seat.   few minutes of silence and then a door opens and closes reverberating for about three seconds.  The clicking of shoes echoes through Warner Hall as she makes her way to the bench.  A minute of preparation and then the Praeludium in G by Bach fills her space and mine.  I sit back and shut all but the Bach from my mind.

 

She's doing an excellent job until - rats.  Bach derails and I sit up in my chair looking around.  A female shout fills the space reverberating for about three seconds.

 

sh*tttttttttttttttttttttttttttttttttttttttt!

 

She goes back a few bars and dances through the problem smoothly.  Now a piece I don't recognize, but it is still clearly Bach until about 6:55.   Her shoes and coat go on and steps click to the door in the distance.

 

And a little magic as a female voice is softly singing Bach.

 

A door opens and closes.  The reverberation is about three seconds and then silence. Time to switch off the amplifiers and make some hot chocolate before getting to work.

She was an organ student in Oberlin and I was in a special room in New Jersey where we were working on the reconstruction sound fields.  A special seven microphone array had been installed in the hall with a computer handling compression mixing and compression in realtime.  The bitstream made traveled eastward to our room where a reasonably convincing illusion of the hall's sound space was created.  We had created a virtual acoustic reality.

 

when subtraction beats addition

The hammer and feather were released at the same time as a few million people watched back on Earth.  Absent air resistance, both objects fell to the lunar surface at the same rate.  David Scott had performed a version of the experiment Galileo Galilei is known for - the one your high school physics teacher said was true if you could ignore the air.

 

It turns out Galileo never dropped anything from the Leaning Tower of Pisa.   Instead he rolledballs of different masses down inclined planes.  The balls accelerated uniformly independent of their mass, but at a rate related to the angle of the plane.  He recognized their acceleration on a 90° ramp would be the same as dropping them from a tower.  One of his insights was if you get rid of friction and air resistance, the problem becomes simple.   This is one of the deepest insights in all of physics - that you can make seemingly ridiculous simplifications and get useful results. And once you know the idealized solution you can add in the fiddly bits that kept you from seeing things clearly at first. 

 

Physicists are trained to simplify wherever possible - (paraphrasing Einstein) just not too much. It's part of the art of the sport. It's so deeply engrained you find yourself using the approach in unrelated areas.  With this background I was struck by a piece in Nature showing people tend to add rather than subtract when solving problems.  It's very common.  Software can get overloaded with features in a hurry consider Microsoft Office.  It's fine to add some functionality over time.  The hard part is understanding something enough to subtract features to improve it's functionality takes serious creativity - in some areas it might be called taste.

 

Once the core ideas are understood it becomes possible to go much further. Before the scientific revolution of the 16^th and 17^th centuries Aristotle's teleological view of the world dominated Western thought.   An object's motion was determined by its nature and all processes were determined by goals.  It's a crude handwavy explanation that sort of makes sense if you don't ask too many questions.   Place a coffee cup around on your desk and give it a shove.  It moves for awhile and comes to a stop.   Everything in motion must constantly be moved by something. Galileo shattered this way of thinking and others built on it.  Newton came up with a good model for motion and gravity that still works well for most of what you and I do - you can and a probe on Mars and fly a helicopter there with it. .  About one hundred years ago Einstein, motivated by some foundational flaws in Newton's work, created "simple, but not too simple" theories that gave a much deeper view that solves a few thorny issues.  That helped to explode our view of the universe.  It also made global positioning systems work. 

 

With this deeper understanding of Nature our minds can travel to the most exotic places. Recently a visualization of a binary black hole system was released.  While the calculations are difficult, requiring a lot of supercomputer time, the core ideas are straightforward.  Enjoy the lightshow as the massive black holes warp nearby spacetime  (the notes are a good explainer)

 

There's much to be learned talking with people in very different fields.  Some are motivated by simplicity, but their approaches are often different and enlightening. .  These people have a lot of skill and experience playing with their kind of simplification.  I'm thankful for conversations I've had with some of you where you've been open enough to let me learn a bit from you.  It's sharpened my approach.

 

 

leaps of faith

minipost

Yesterday I had my first jab of a Covid-19 vaccine - specifically the Pfizer mRNA vaccine.  Despite political, production, and distribution issues several vaccines appeared and more are coming.  Going from decoding the SARS-CoV-2 genome to first injections took only about a half year and a year later a few hundred million doses have been produced. While some corners were safely cut, the real story - at least for the new mRNA vaccines - began nearly thirty years earlier.  

 

Katalin Karikó's work will certainly win her a Nobel Prize next year.   Here's a good telling of the story.  A major point is the work was judged unworthy and finding support was nearly impossible.  After about ten years another player, Drew Weissman, entered and the two of them managed to crack the final bits of the problem.  He'll certainly be sprinkled with the Swedish holy water too. The mRNA approach is important well beyond the current pandemic - it may mark a fundamental change in medicine.  It wouldn't have happened - at least not as soon as it did - without a certain type of reserch.  

 

Curiosity-driven fundamental research requires a certain type of scientist, time and resources.  While much of it fails to produce an immediately useful result,  it has an established track record of changing the world.  Industries don't do this kind of work anymore.  Most universities shy from it - there's a tendency to want results-focused work.  When it's funded you usually find it in physics and astronomy  rather than the biological sciences and that's a problem.   These leaps are driven by hope and curiosity.  They open doors that often require more than a decade of work - usually by other people in different organizations.   Expanding this work is how you create radical change.  I'd never argue results-driven research should be cut - after all, that's where the next five to twenty years come from.  But I'd love to see the Katalin Karikós of the world given more of a space.  And then there are the spin-offs - a good deal of the instrumentation used in medicine came out of  fundamental physics - but that's another set of stories.

 

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.

 

 

green flight

Two years ago the Environmental Protection Agency reported aviation accounted for about three percent of the nation's CO₂ emissions, or about twelve percent of transportation.  The international figure is about two point five percent.  These may not seem huge, but they've been growing steadily and, post pandemic, should continue their growth.  Making matters worse is the global warming contribution from the cloud-like contrails produced by the jet engines at altitude.   It's difficult to study, but indications are the contribution may double the global warming impact. 

 

A number of approaches have been suggested and are in various stages of testing.  Moving to bio-fuels isn't the greatest solution as growing and producing biofuels has issues and you're still producing contrails.  In the short term some airlines will move to it, but that may be part a PR and carbon credits game as much as anything. 

 

Electric airplanes exist and there are even a few (very) sort haul commercial flights.  The problem is the specific energy of the battery - how heavy is a battery per unit of energy storage.   Turbine fuel stores about eighty times as much energy as a safe lithium-ion battery of the same weight.  Airplanes frequently carry large amounts of fuel - the weight of fuel burned on a cross country trip is greater than that of the the passengers and crew.  The range of a battery powered airplane is severely limited even after accounting for the great efficiency of an electric motor.   We could get a lot closer with exotic batteries that aren't anywhere close to reality, but even then you're talking about a propeller driven (slower) aircraft. 

 

Hydrogen often comes up as the perfect clean fuel - the combustion product is just water.   Although it's the most common element in the universe and accounts for most of your body's atoms, we need hydrogen gas and that's extremely rare on Earth.  Hydrogen gas (H₂) must to be produced and it takes a lot of energy to create it - more than you can get out of it.  Most of it is produced from a petrochemical process that involves carbon emissions.  This is called black or grey hydrogen and, if you manage to capture most of the carbon emissions it's called blue hydrogen.  What you want is green hydrogen - hydrogen produced using electrolysis with electricity from wind, solar or nuclear power.  That seems like a nice use of excess intermittent power. 

 

It's important to think of hydrogen as an energy storage medium - a non-rechargeable battery of sorts.  It has a very low - essentially unusable energy density at atmospheric pressure.  You'd need impossibly large tanks (think about Hindenburg sized tanks) or you can compress it or liquify it and shrink your tanks to something more manageable.  In gas form at a very high but probably safe pressure it needs about five to ten times the volume of  jet fuel. Liquid hydrogen gets you down to about three and a half times the volume.  

 

Engineering is all about finding an optimal solution to several problems that generally interact.  You could convert a turboprop or turbofan to burn hydrogen and see where that takes you.  Turboprops seem to be workable on short haul routes (1,000 km or less) with small passenger loads (under 100 passengers).  They'd be slow and fly at lower altitudes than today's jets.  Turbofans present a number of problems - at altitude they're making contrails and the range and payload isn't great.  One needs to think a bit out of the box.   

 

You might use a hybrid jet fuel/hydrogen engine that climbs to cruising altitude on jet fuel as fuel consumption is much greater in that phase. Then the switch to hydrogen fuel is made when the engines are throttled back at cruise altitude.  You could also design a lifting body aircraft that has a lot of internal volume for liquid hydrogen fuel tanks without being too large for conventional airports.  Tricks might get you across the US with a few hundred passengers, but flights across the Atlantic or Pacific would require something more. 

 

The prop-driven airplanes present other opportunities. A fuel cell converts hydrogen to electricity and electric motors are more efficient that jet engines.  There are a number of little problems that can be overcome, but a fuel cell propeller airliner may just be a short to medium range solution.

 

I didn't go into the NOx problem.  The high heat of combustion in a jet engine creates nitrous oxides when the nitrogen in the air is heated to high temperatures.  That's a problem - particularly at the high altitudes jets fly at and burning hydrogen won't fix it.  The way around it is to use fuel cells and electric motors, but that's for lower altitudes and slower speeds.  There isn't an ideal solution - you just hope to reduce as much as you can.  

 

Airbus is working on the problem - or at least they were before the pandemic.  I can believe the target date for the propeller aircraft, the lifting body is probably more than fifteen years out.

There may be a near term niche for hydrogen powered flying vehicles.  Agricultural and inspection drones are much larger than hobbyist drones.  They're limited to half hour flight times with batteries, but new fuel cell drones with small high pressure hydrogen tanks have appeared in Korea.  They can fly for hours and that may be the first practical opening for aerial hydrogen.