omenti

getting down to the bedrock

Some areas are built on foundations of fundamental principals that can be built upon.  For example many of the world's religions have a form of the golden rule in their bedrock.  Physics has a few of these cornerstones that are so deep they're considered beautiful and have become guides.  I've been thinking about one of them - complementarity -  a lot recently.  Particularly as it appears outside of physics in many areas probably including some you're used to thinking about.

 

Neils Bohr and Albert Einstein were contemporaries - peers actually.  Both were great sources of quotes.  Einstein's fame is such that it's difficult to figure out exactly what he did say without original sources. Bohr's lack of fame outside of physics makes it easier. Here are a few:

 

“We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct. My own feeling is that it is not crazy enough.”

“Never express yourself more clearly than you are able to think”

“A physicist is just an atom's way of looking at itself.”

“There are trivial truths and there are great truths. The opposite of a trivial truth is plainly false. The opposite of a great truth is also true.”

 

None were meant to be flippant and the last one is one of the richest quotes I know.  Really deep ideas have meanings that go beyond the surface.   As an example consider this question

 "is light a particle or a wave?"

 It turns out it's both, but sometimes it's most useful to describe it as a wave while other times you treat it as a particle.  It's impossible to apply both descriptions at the same time.   The essence of complementarity is there are different ways of looking at the world and each can have its own language and domain where it's true. 

 

You can step back a bit and look at a satellite in orbit.   Physics developed by Newton are good enough to put it there and predicting where it is to good precision, but if you're worried about the accuracy of its clock you need to bring in relativity.  Einstein and Newton offer very different theories that describe orbital motion and how clocks keep time.  Relatively turns out to be richer, but Newton's ideas are good enough for almost everything people normally do - that and I'd hate to describe the motion of a volleyball using special and general relativity.  

 

I won't go into quantum mechanics, but complementarity is at the core how you think about things.  That and like Newton and Einstein's models, there are boundaries where one is more useful than the other.  The trick is knowing both and where the boundary lies.  It's for another discussion, but I think complementarity is a good basis for talking about the concept of free will. 

 

Bohr was so taken with the idea of complementarity that he made it part of his coat of arms with a nod to Eastern religious philosophies and the Order of the Elephant.  (how's that for clickbait?)

 

Light offers another example. Newton used a prism to break whiteish sunlight into a spectrum of colors.  Later Keats objected to the beauty of science claiming Newton unwove the rainbow.  

Do not all charms fly/at the mere touch of cold philosophy?/There was an awful Rainbow once in heaven. 

 In reality something deeper is afoot.

 

 Consider a yellow light on your desk.  The wavelength of the light makes it look yellow, but if you are moving towards at a constant velocity you observe a shorter wavelength.  If you're moving fast enough it looks blue.  Faster still and it's ultraviolet.  If you're moving away the wavelength lengthens and it shifts towards the red.  In fact by selecting your velocity with respect to the light, the wavelength can be anything you want.   In this view of nature the color of light only depends on your velocity relative to it.   It may not seem useful, but it turns out to be one of the most important tools for measuring the size and age of the Universe. 

 

Complementarity appears all over physics and turns out to be a useful way of thinking about new phenomena.   Over time I've come to think of it in areas outside of physics.  The spoken work and a television show can both get across their own versions of something.  Neither is complete and understanding both can lead to a deeper appreciation.  Picasso and Rembrandt had very different portrait styles and both tell us something deep about their subjects in very different ways.  Mix different forms of art - a piece of music might describe the feeling of Winter quite differently from a painting, but both can offer deep if incomplete views of the feeling of the season.   Sports are offer many examples.  Movement in a sport can make statements that added with the emotion of the crowd give a more complete picture.

 

You can't use a flat Earth, geocentric universe, or being able to turn off gravity for an hour tomorrow.  The descriptions have to be valid in some domain  in the first place.  But having two good but very different representations of something in your head at the same time may just lead to a deeper understanding.  Usually you're not thinking about deep truths, but that's fine.  This doesn't come easily, at least not to me, but it's a lot of fun once you get the hang of it. 

 

 

in praise of techs

mini post

1874 saw the opening of the most important inventions of the 19^th century - The Cavendish Laboratory at the University of Cambridge.  Serious science began to take off in the 1850s in universities.  It was mostly applied and work aimed at solving the problems of the day - railroads and telegraph.  Cambridge was late to the game, but their approach was revolutionary.  Apparatus and expertise were concentrated at one location.  Research cultures emerged. Not only was this cost effective, it freed up researchers to explore new classes of problems - not only hypothesis based and applied work, but true exploration.  That turned out to be the fuel of scientific and technological change in the following century. 

 

The model spread and by the 1890s and areas of deep expertise began to appear.  A dramatic example is the race to zero - how experimentalists tried to achieve the lowest possible temperatures.  Three institutions were deep into the game, but success and failure came down to who had the best apparatus and laboratory technicians. The experiments had become so difficult that expert technicians who built, understood and modified the experimental apparatus made all the difference. 

 

The public often sees science as the quirky theorist standing at her slate board and, chalk in hand and on her shirt and pants,  having deep thoughts. In fact most of it is very careful labor that can consume a small army of people for years to get a result that something didn't exist (that's as important as finding something!)  The Nobels celebrate the principal scientists and praise is warranted, but it often misses the supporting staff. (I think the Nobels have their place as they tend to focus on the frontier rather than hypothesis driven work.  I wish they were more inclusive, but another story)

 

Here's a short video on a tech at EGO-Virgo - the gravity wave observatory near Pisa, Italy.  Three such instruments exist with a forth coming online in Japan soon and a fifth under construction in India.  Able to measure distortions more than ten thousand times smaller than the diameter of a proton, these are far and away the most precise instruments ever built.  The technicians responsible for various bits and running them made it all possible.  I've worked with people like this - they're among the greatest craftsmen and women in the world.

yet another confusing word

These days we're hearing and talking about a future that is suddenly very difficult to predict.  Uncertainty is frequently invoked.  I know what it's supposed to mean, but the scientific context is very different.  It's one of those words - theory, hypothesis, work, energy, power, model, significant, natural, ...  - with a very specific scientific meaning at odds with their popular meaning.  (science communication is hard)

 

Who knows what's going to happen? frequency comes to mind,  while uncertainty is well defined in the context of science.  It's the quantification of how tightly we can constrain what we don't know.  That's a very powerful concerpt.  Being the simplest of the sciences, physics has the most rigid requirements.  In order for a discovery to be accepted by particle physicists uncertainty that it could be something else has to be lower than one part in three point five million - the five standard deviation level.  People living in this world spend much of their time thinking about what could go wrong and devising other measurements to disprove their original hypothesis.   We speak in terms of confidence levels.  

 

Henry Cavendish was one of the first to work at understanding and minimizing uncertainty when he weighed the Earth to determine the gravitational constant.  Even today the measurement is difficult as gravity is incredibly weak as forces go.  Without going into details,  Cavendish built an exquisitely sensitive  torsion balance that measured the attraction between small lead spheres and a much larger lead sphere.  His early measurements made sense, but was it just gravity?  Perhaps there was a bit of a magnetic effect .. he rebuilt the experiment with a large magnetic ball replacing the lead ball.  This wasn't to rule out magnetism as much as to set a quantitative limit on how large the effect was.  Then he turned to thermal effects heating and cooling different parts of the experiment.   He was left with his best measurement and the level of confidence that he had removed all other controllable effects (including human error).    

 

The game becomes trying to make a more precise measurement and perhaps seeing something new in the process - some measurable effect that can't be explained conventionally.  A good deal of science advances in this way.

 

Here's a cute introduction to uncertainty that I almost really like - the bear in the moonlight - almost as it doesn't touch on fundamental uncertainty.

 

There's another deep form of uncertainty - you've probably heard of Heisenberg's uncertainty principle and Schrödinger's poor cat.  Broadly stated Heisenberg showed that it was impossible to perfectly know both the position and momentum of anything.  He called it ungenauigkeit (inexactness) or unbestimmtheit (undeterminedness). Niels Bohr called it unsicherheit (unsureness).  Even today German physicists (like their Prime Minister, Angela Merkel) will call it unschärfe (fuzziness).  All of these terms are more descriptive of the physics than uncertainty.  The use of uncertainty suggests to some there is an exact value and we just can't measure it.  Instead there is just a probability distribution.  It is indeed fuzzy - at a microscopic level all of the atoms that make us up are fuzzy - it's just our world is mostly too large to notice.

 

In some parts of my life I try to avoid what is usually thought of as uncertainty, but when you want to really understand something diving in and reducing your uncertainty and increasing your level of confidence is a powerful tool. 

 

beyond 3d

Ask a physicist, biologist or chemist what got them interested in science and chances are they'll talk about a dramatic single moment - some refer to it as a calling.  I've written about mine on Sulphur Mountain in Banff.  Two young physicists took the time to try and explain their cosmic ray telescope.  Much of it was beyond me but the idea that something from outside our solar system slammed into the upper atmosphere and created a shower of other particles stuck.  And that these wouldn't live long enough to make it from the upper atmosphere to their telescope unless time was different for them.  I had no idea how that worked, but the fact that they could show that universal time - a master clock for the universe - didn't exist ate at me for nearly two years.  I didn't know it but I was about to become a physics student.

 

Somehow I found two correspondence mentors who taught me a little physics and more math.  Two years after Sulphur Mountain I finally understood why time ran more slowly for those speeding muons than for me.  That and what E =mc² really meant and how Einstein figured it out.  Einstein figuring it out was extraordinary, but more extraordinary is Special Relativity is simple and clear - beautiful - even if the results seem odd.  A high school student could read his paper and follow everything with just basic algebra and trigonometry.  

 

There are more than a few explanations in print and online.  To really learn it you need to puzzle it out for yourself with pencil and paper guided by a good textbook and problems.  Instead I'll talk about how he came to that flash of insight. 

 

Around the age of sixteen Einstein had been kicked out of the German school system.  He moved to Switzerland and spent a year at a school that put a premium on visualization and individualism.  There he learned about electromagnetism - light was just oscillating electric and magnetic fields that traveled at the speed of light. He found himself wondering what it would be like to run alongside a beam of light. Could he visualize what these fields looked like?

 

Maxwell's equations said that electromagnetic radiation - light - travels at 300,000,000 meters per second in a vacuum.   If he was going that fast the fields would vanish.  That didn't work.  Since Galileo physics was built on the idea of relativity.  The laws of physics didn't depend on how fast you are traveling.  All you can measure is the velocity of one object relative to another.  He had run directly into a wall.

 

For a decade Einstein kept at the problem.  Finally he went with a crazy idea (to be fair he tried a few crazy ideas).  What if the speed of light was the same for all observers no matter how fast they were moving? If you were on a train traveling at 80% the speed of light and pointed a flashlight forward, you'd measure the speed of light from the flashlight as 300,000,000 meters per second, as would a stationary observer watching from the ground as your train sped past.

 

The way out of this paradox was the person on the train and the observer on the ground experienced time differently.  Two events can happen simultaneously for one observer and at different times for another and both could be right.  Understanding exactly how that works requires learning about special relativity and you can't avoid the math and some sketches.    

 

Einstein offered the following gedankenexperiment (thought experiment):  An observer near a train track watches a speeding train go by.  Exactly as the midpoint of the train goes by two bolts of lighting strike the train - one at the front, the other at the back.   The distance from each strike to her is exactly the same and she says the lightning strikes were simultaneous. 

 

A passenger is sitting at the train's exact midpoint.   Because the train is moving the light from the pulse at the back has to travel a bit further than the pulse from the front. He says the strike at the front of the train came first.  They weren't simultaneous.  The key is it's simultaneity that's relative.  Once you understand that the algebra is simple.  The construction you are left with is space and time are intimately connected in a four dimensioned coordinate system called spacetime.  Spacetime doesn't change, but objects in the 3d world we perceive and time have different measurements for observers who are moving relative to each other.

 

I remember the amazing feeling when it came together in my mind.  It was early June around sunrise.  I got on my ten speed and rode as fast as I could.

 

 

 

 

lessons

Recently Om wrote an excellent piece on Derek Jeter’s career and some lessons one might draw from it. Even if you don’t like baseball, it’s worth reading.

 

Consistency, finding opportunity, leading by example .. and the ultimate goal.

 

One of my heroes is Ray Davis. I got to know him when I was a grad student and postdoc at Brookhaven National Laboratories. He was an experimental physical chemist who was doing some interesting solar physics. He was also of those people who mentored those more junior by example. I sailed with him on his homemade sailboat and joined him on numerous nature walks around the BNL installation as he photographed almost everything. He’d show up on Mondays with bandages from whatever home repair he had attempted. 

 

It’s worth reading a personal statement he made in 2002

 

also check out how people recognized him at the bottom. I’m sure he didn’t put that in himself. He was exceptionally humble.

 

His statement doesn’t go into the controversy and drama of the Homestake Gold Mine experiment. By 1960 physicists had a good idea how fusion took place in the Sun. It’s a somewhat complicated multistep process and different from how manmade fusion machines or bombs work. Some of the energy is released in the form of neutrinos. You may have head about neutrinos. They have a very small mass and barely interact with matter. A standard comment is more than half the neutrinos that strike a piece of lead a light year thick will travel though as if it didn’t exist. But the Sun was making a lot of electron neutrinos and a few will interact. In the late 60s Ray decided to count them and nail down what was going on in the Sun’s core.

 

He was exceptionally careful. Every month he was able to count about three dozen argon37 atoms They started out as chlorine37 but were turned into argon37 when an electron neutrino struck them. Ray spent years making sure hhis results were accurate. His numbers were very consistent… and about a third of what everyone knew was required for the Sun to shine like we see it. It seemed eithre Ray was wrong or the solar models were wrong. Ray persisted. People were in awe of how careful he was. The solar models were also holding up in other tests.

 

It turned out new physics was afoot. Ray was only sensitive to one type of neutrino - the electron neutrino - the type the Sun had to generate. What they found, when another observatory was built that detected another type was neutrinos oscillated from one type to another as they sped along. It was as if your Ford changed into a Chevy and then a Toyota regularly. You owned a “car” that was an admixture of these different brands. Startling new physics. Ray had peered into the core of the Sun with a tank of chlorine about a mile underground in South Dakota and by not giving up when the numbers seemed wrong, found Nature was answering with a new question

 

Ray was sprinkled with Swedish holy water in 2002 for his work.

 

It is remarkable that his institution - BNL - gave him that level of freedom. It’s also remarkable how he stuck with it and impressed all of us with the beauty of his work.

 

lessons…

connecting the titanic, sputnik and dealing with forgetfulness

1955, Fred Whipple had just been appointed to head the Smithsonian Astrophysical Observatory in Cambridge.  The International Geophysical Year was less than two years away and he wanted to involve citizen scientists as much as possible.  Whipple was one of the few who realized a satellite was likely and set about creating a web of radio operators to monitor and relay transmissions from satellites along with groups of amateur astronomers who could optically track their orbits.  Operation Moonwatch was formed and by Sputnik's launch over 200 teams were in place. 

 

Tracking a satellite was done with a clock and a low power telescopes that could read azimuth and declination.  The National Bureau of Standards time signal broadcast on WWV in Fort Collins, Colorado used as the reference clock and most people into amateur astronomy had a shortwave radio. Readings from stations separated by hundreds of miles were sent by amateur radio operators to a computer at MIT that gave the project a bit of its precious time.  More clusters of readings would come in from around the world and a model of the satellite's orbit generated an ephemerides - predictions of where it would be. Later specialized cameras were developed by Bell Labs to automatically generate satellite ephemerides as well as tracking ICBM tests, but Moonwatch was a success and lit the imagination of a few people.  

 

In physics it's common to turn a problem on its head to gain a bit of insight.  Operation Moonwatch used known positions on earth and an accurate clock to measure a position in orbit.  What if you put synchronized clocks in space and measured how long it took radio signals to reach a position on earth?  With enough satellites with synchronized clocks you could triangulate a position anywhere on the Earth's surface.  The technical details were difficult details, but the basic idea was simple.  

 

It turns out accurate navigation is very difficult and expensive and a limiting factor in fighting the cold war.  It was so difficult that as technology progressed ARPA decided to push ahead with a satellite based global positioning system - the inverse of Operation Moonwatch.  It was a bargain for what it gave to the military.  Finally a good enough signal was made available to civilians and navigation changed.¹ 

 

GPS doesn't work everywhere.  It would be nice to track things indoors and at a lower cost. Bluetooth and WiFi are currently used -  usually measuring signal strength from several transmitting beacons and triangulate a position.  Sometimes it's just proximity to a single beacon - a lighthouse model.   The approaches aren't very accurate - three to ten meters is common.  Good enough to track your phone as you move around, say, in a mall or subway, but doing better would be nice.

 

This is where the Titanic comes in..

 

On April 15, 1912 the Titanic struck an iceberg.  Frantic radio signals went out, but there was confusion among rescue vessels and people on land trying to coordinate the rescue effort.  Sometimes it takes a disaster to create order and an effort to regulate radio frequencies began soon after. Transmitters were assigned narrow swaths of the electromagnetic spectrum that were large enough to effectively communicate with receivers that could tune to those frequencies. Regulations changed as larger chunks of this resource were needed - AM radio required more than Morse Code, FM radio even more and television much more. Government would parcel out these increasingly scarce resources, but power was also regulated and it was possible to give much larger chunks to low power short range communications - WiFi and Bluetooth are examples.  Most of radio engineering tried to pack as much information into as little spectrum as possible and to build transmitters and receivers that could be accurately tuned to specific frequency ranges  If you waited for some technology to catch up there was another way (actually several, but I'll only mention one) way to do radio.

 

You may have heard about ultrawideband (UWB).  In the mid 2000s it was supposed to be a good way to send large amounts of information over short distances.  Cheaper and higher bandwidth than the WiFi of the day. Often existing technologies are improved with scale and an embedded base making it difficult for new players.  Sophisticated coding technologies and enormous penetration (WiFi has greater penetration than smartphones) cemented WiFi as the prime high bandwidth low range wireless connection.  In a few years UWB went from redundant to lagging. Many thought it was dead, but it had a few advantages in some use cases.   

 

Here's how it works.  Rather than sending out a precisely tuned narrow band frequency, UWB sends out narrow (in time) digital pulses that "splash" over a very wide frequency range.  The signals are usually only one or two billionths of a second long and aren't sent that often - a hundred thousand to ten million a second are common rates. The frequency range is so wide that usually at least some of it can pass through objects that block signals like GPS and WiFi.  It's also so weak that narrowband communication can't detect it.²

 

 Imagine scattering a few UWB transmitters around where you know their location with some accuracy.  Now start transmitting synchronized pulses.  A receiver notices the time of arrival of each signal and, using the fact that light travels about 30 centimeters in a billionth of a second, can triangulate it's own position.  Accuracy is about ten centimeters - about four inches.

 

A use case I'm familiar with is finding the locations of players in a beach volleyball game.  In international FIVB games a very small (less than a half ounce) UWB device goes in the back of each player's  shirt or sports bra.  Their positions are tracked within ten centimeters about a hundred times a second and accelerometers and a compass send out rotation and orientation information on the UWB signal that the announcers, coaches and sports science people use.  Four transmitters are used and all four players are easily tracked.

 

It would also be useful for augmented reality and Apple has included an UWB chip in every iPhone 11 - the greatest deployment of the technology so far.  For now it's being used for data transfer, but wait a bit.  Someone could also make very cheap ($10 or less) postage stamp devices that might be powered by available light that could be location tags.  Put them on your keys, glasses, remote control .. anything you tend to lose track of.  We went through trying to manage dementia with my mother.  I would have paid a lot for this capability.  And thousands of other uses from amateur sports to tracking boxes accurately in warehouses.

 

There are probably some bad things that can be done with it.  We need to be thinking these things through, but our track record isn't exactly good. 

__________

¹ It also gives a very good frequency standard and a timing signal.  Without this our mobile phone system, high frequency trading and a host of other core technologies we depend on would break.  This is an issue as GPS is vulnerable to attack and we've done almost nothing on backup technologies. 

² The FCC defines it as taking up at least 500 MHz of spectrum somewhere from 3.1 to 10.6 GHz.  Power is under -41.3 dBm/MHz .. or 75 nanowatts.  Since it only deposits a tiny bit of power in any narrowband frequency, it's just below the noise floor of a narrowband receiver.  Fortunately it's straightforward to build a receiver that can detect the signal. 

hacking creativity and collaboration

A recent Bell Labs reunion celebrating the 50^th anniversary of Unix gave me a chance to visit with old friends I hadn't seen in a long time.  Some of the people had moved into industry (Google was a popular landing place) and others found university posts.  I found myself thinking about the differences between the evaluation process of major research universities and the old Bell Laboratories.

 

In a run that lasted about five decades Bell Laboratories - call it Bell Labs Classic - was arguably the most applied research organization in the world.  There were certainly warts and missed opportunities and it effectively came to an end about five years after the mid 80s breakup of AT&T, but it was an astonishing place while it lasted.  I'm continually been struck by differences between that institution and almost everything else I've run into.

 

In universities hiring and promotion (tenure and beyond) is strongly connected to ten or so recommendation letters from leaders of the field in different universities. The authors are almost always experts in the same subspecialty as the junior researcher.  Bell Labs was different. There was an internal ranking that extended throughout the research organization. A department head would rank their people and the results were merged with the rankings from the other department heads in the same center. These rankings would then go through the same process for the next two levels up until a ranking of the entire institution existed. An expert in a field might receive fantastic marks inside their department, but do poorly further up in the process as others might be unaware of them. Interdisciplinary work would stand out and the highest ranked people tended to have one solid speciality along with work in centers far removed from their own.

 

I entered the Labs as an experimental particle physicist. There were a number of physics groups, but no particle physics. I was initially assigned to an applied physics group and found myself working with a number of other groups as I scrambled to find my way. In the process I made connections inside and outside the center and found some encouragement to trade help with others.   All researchers were given the title of  MTS  - member of the technical staff.  It resulted in a certain equality that made approaching others easy.  

 

Most researchers weren't interested in management, but there was one small step up.   If you were in the top ten percent or so for a number of years you became a distinguished member of the technical staff and given more freedom. In my case I was initially given a day a week and resources to do anything I wanted.  Those projects were all collaborations far from my home organization. 

 

Guaranteed funding for pure and applied research went away about five years after AT&T's breakup and folks had to attach their work to business units. It’s what killed Bell Labs, but realistically it was the only logical path for the company at the time. Bell Labs Classic could only exist as part of a regulated monopoly, but that’s another story.  

 

Some universities are playing around with this kind of ranking to stimulate interdisciplinary work. I don’t think it works in industrial applied research.. at least not at scale, but it might be worth considering.  Of course there are different mechanisms in other organizations - places like Pixar - but the difference between Bell Labs Classic and research universities is quite possibly the result of collaboration encouraged by a simple ranking process.

 

mad science

It seems Apple released a new smartphone yesterday. This one has several reasons to make me want to upgrade, but the most drool-worthy is its power as a computational camera.  I'll leave it to other to write the reviews and compare it to Google's efforts - a new iPhone isn't in my budget this year.  But perhaps a few words on computational photography are relevant.

 

Computational photography has been around for over sixty years.¹  In particle physics you slam particles into each other and carefully study the wreckage that emerges from the collision. About sixty years ago bubble chambers came into use.  The idea was to record the wreckage in three dimensions.  A chamber was filled with a transparent liquid like liquid hydrogen, kept just below its boiling point. Just before a fast moving particle entered the chamber a piston at the bottom of the chamber was dropped suddenly causing  the liquid to superheat. The incoming particle collides with a particle in the liquid - usually a proton if the liquid is hydrogen - and charged particles from the collision leave a trail of tiny bubbles in the sensitized superheated liquid.   Three cameras at right angles to each other simultaneously captured three views of the bubble tracks and the piston is moved back into position waiting for the next collision.  

 

A large magnet surrounds the chamber causing the particles to bend one way or another depending on their charge.  The slower a charged particle moves, the more it curls.  The photographic sheets are developed and "girls" - it was considered women's work - would trace the tracks by hand with digitizers creating lists of coordinates for each track that a computer program could use to compute the fundamentals of each collision.²  This type of computing was the most demanding of the day.   In the late sixties and beyond recording the collisions directly in digital form using a variety of "counters" took over and the scale of experiments and necessary computation exploded.

 

By the late 70s people were beginning to categorize medical x-rays and ultrasounds computationally and resonance imaging began to emerge.  The computational requirements were stiff in the day, but your phone could easily handle the computing required for your MRI.  It has been argued that this form of computational photography has had the largest impact on human health of any form of computation.

 

Playing with photographic images from telescopes and microscopes was  necessary in science, but the techniques quickly migrated to computer science labs.  Just as the Utah Teapot was the universal test for 3d imaging, a photo known as Lenna was the ubiquitous test for imaging algorithm research in male dominated CS departments during the 70s and 80s.  It wasn't unusual to see her image appear in several papers in a single journal issue.  Journal images today aren't as sexist.

 

Some of what went into academic image processing made its way into Photoshop in the late eighties.  Photoshop went on to be a preferred platform for creative artists to do computational post-processing of their images.  Take a photo on your camera and play with it on your computer.

 

But what if the camera and computer could be combined into something that could redefine imaging?  I'd argue that took place in science some time ago as the imaging part of telescopes, microscopes and particle detectors had began to require built-in computation.  It's been in the past few years we've seen the emergence of a new type of photography in handheld cameras.  Smartphones, with vast development resources, are leading the way and we're on the verge of an explosion of new techniques and ideas.

 

At this point it would make sense to talk a bit about the basics of 2d fourier transforms to get a sense of how that's done.  Here's a short non-technical introduction that gives a sense of a basic function.

 

 

The computational power of the latest smartphones is staggering and, at least in Apple's case, a good deal of it can be devoted to computational photography.  Currently much of it is used to improve snapshots that would otherwise be unusable.  Noise can be reduced while still keeping important detail - often using psychological models of human perception, the dynamic range of an image can be extended by taking a number of shots and bringing out detail in dark areas and suppressing burned out overexposed regions, realtime video can be overlayed with other information creating a computation synesthesia of sorts, machine learning is becoming useful in many ways,  .. the list goes on and on.  

 

I'll offer one that could appear in about a year with the next generation of smartphones.  Time of flight image sensing is now sort of practical for a smartphone and will probably be a feature in high volume phones like the iPhone next year. Basically a pulse of infrared laser light is sent out to an object and the time it takes to go out and return is used to calculate the distance.  This is done for a somewhat smaller image than your camera takes - a few hundred thousand to a million pixels. But these pixels now have distance information in addition to enough image information that it can be used to create a distance map for the full image from the main sensor.   This could be very useful in augmented reality, but here's one I'd like to see.  Take two or three phones on tripods and point them at a dancer, athlete or someone getting physical therapy.  A very accurate motion capture video could be quickly made and you wouldn't have to spend $50k and up on specialized equipment.  Coaches and physical therapists would be delighted. 

 

A thousand other uses will emerge we haven't thought about. Independent of their platforms there are strong reasons why Apple needs a great computational camera.  What will separate winners from losers will be usefulness, playfulness, and great user interfaces and experiences.  That's the hard part. 

 

For the best photos a good photographer is still required and the tiny lenses and sensors on smartphones are limited by basic physics.  But always having a camera with you and one that can correct basic mistakes is a serious plus.  That and there are emerging capabilities that will take photography in new directions.  

__________

¹ digital computational photography.  I won't go into details here, but optical computation has been around even longer.  If you're interested in the subject realize a lens is an optical computer capable of creating a Fourier transform.

² I like this example as a neutrino slams into a protron bangnig the vacuum hard enough that a D⁺ (d plus meson) appears.  It is composed of two quarks:  charm and anti-down.  I have a fondness for charm quarks:-)  Also this was made during the twilight of bubble chambers in the late 70s. 

 

 

 

abigail van allen's layer cake - catalyst for the last half of the 20th century

I was in my second year of grad school and had gone to dinner at my advisor's house.  These dinners were always interesting and the deserts were a near match.  That night we had a wonderful homemade cake.  A layer cake rolled in the shape of a log, filled with fresh fruit and coated with a thin layer of bitter chocolate.  One of the guests - James Van Allen - yes the guy the Van Allen belts are named after - remarked on the cake and told us the story about Sputnik starting the space race was all wrong.  The real beginning came years earlier in his living room over his wife's excellent layer cake.  Reality is often more fascinating than the recent history we hear in school.

 

It was around 1953.  Van Allen and a group of physicists were at his home after a formal meeting.  This night a critical step was taken.  After talking about new learnings from balloon and sounding rocket explorations of the ionosphere.  Someone suggested maybe an Earth orbiting satellite would be possible soon.  After all - this von Braun guy was making a lot of noise about space travel being practical.

 

Indeed Wernher von Braun had been trying to popularize space travel.  He had teamed up with science fiction writers and later with Disney and Collier's trying to convince the public. Although von Braun was charismatic, he wasn't taken that seriously.  The only thing the government wanted him for was leading the Army's program to be rockets that could deliver nuclear weapons.

 

Enjoying the excellent cake was someone who could make a difference.  Lloyd Berkner was one of the most respected scientists in the United States.  He had the ear of generals and even the President.  He made an interesting suggestion.  Maybe the way to learn more about near space would be a multination collaboration like one that explored Antarctica.   Given global tensions it could be useful for political reasons and would spread the costs. Larger sounding rockets could be built along with expeditions to the poles.  Maybe even a satellite.   Everyone at the dinner loved the idea and the International Geophysical Year was proposed soon afterwards.  Ultimately dozens of countries and hundreds of scientists were involved.  The target year would be 1957.

 

Van Allen and the other near space guys kept proposing satellites with no luck.  Then, a few years later, Berkner found the key.  President Eisenhower was focused on avoiding WWIII and countering the Soviets.  Something like a satellite for science was nothing but a distraction.  Berkner had used the "it will shock the other side" argument without luck.  Then he changed gears and suggested it could lead to spy satellites.

 

Eisenhower was a general.   Having great surveillance is deeply embedded in military DNA.  Spies on the ground, high altitude aircraft, code breakers .. whatever it took.  The only trick with a satellite, Berkner said, would be to establish Earth orbit as neutral territory.  A small scientific satellite could set a precedent.   Eisenhower agreed and the Navy ultimately won a competition to work on Project Vanguard - a satellite to be instrumented by Van Allen's team. 

 

The Soviet Union's ICBM project was led by a scientist more interested in space flight than ICBMs.  He realized an ICBM would make a dandy satellite launcher and when Khrushchev took power managed to convince him on an ICBM program and added an Earth orbiting satellite would have a great political impact.  Khrushchev agreed, but what he really wanted was a big ICBM.

 

Through the International Geophysical Year interactions it had become clear that the Soviets were building a satellite - indeed that it would launch in the Fall of 1957.  It seemed like a fantastic cap to the year, but the knowledge and excitement didn't go beyond far that group.

 

When Sputnik (fellow traveler) launched it was mostly ignored by the Americans - certainly the government.  The New York Times made a big announcement and people went out to look.  Satellite tracking became almost a hobby for some (that was the genesis for a global positioning system, but that's another story), but America wasn't quaking in fear.

 

The American government was happy - perhaps delighted.  They weren't first, but this little Soviet metal sphere orbited over American territory several times a day.  Precedent had been established. It would take time, but the Americans would get their spy satellites.

 

The story most of us know came from Texas.  Lyndon Banes Johnson worried whoever controlled space could control Earth - an old sci-fi trope.  LBJ also happened to be the Senate Majority Leader.  He gave impassioned speeches about falling behind.  His words resonated with the public and early American rocket failures only increased public anxiety.  

 

And what about Van Allen and the other scientists?  Johnson managed to open the serious money spigot.  It became clear that ICBMs made great satellite launchers with modest changes.  The scientific study of space was a dandy idea to help prove in new rocket technology.    STEM education in the public schools sprang up largely out of Berkeley and MIT.  The world was changing.

 

The Van Allen Belts?  They were discovered using the early Explorer series of satellites in 1958.  The interaction of the Earth's magnetic field and the solar wind was beginning to sort out. 

 

So that's the secret .. really good layer cake.

 

why revolutions sometimes need astonishing simplicity

Physics is, by far, the simplest science.

 

I probably have said it too much and it can raise eyebrows. It may not seem that way as we have a reasonably deep understanding and the required knowledge can seem esoteric, but that complexity isn't central and misses the point. What is astonishing is that you can often make seemingly absurd simplifications - spherical bodies, frictionless surfaces, planets that behave as if they were points - and get not only a pretty good answer, but a deep understanding of what is really going on - a hint of how Nature really works.

 

Galileo Galilei was said to have dropped balls of similar size, but different weights from the Leaning Tower of Pizza and summarized that they fell at the same rate.  In fact he probably never did the experiment.  Instead he rolled balls down inclined planes showing their acceleration depended on the angle of the plane rather than their mass.   He suggested a very high angle (vertical) was equivalent to balls of different weights falling at the same rate.   The acceleration from gravity was more important than friction against the plane and air resistance. Assuming you understood air resistance and friction against the plane you could add these effects later and get a better answer.  His insight is probably the most important idea in physics.

 

This realization that physics was fundamentally simple brought together ideas from a variety of sources and led to an idea that went beyond revolutionizing physics to revolutionizing how we think about our place in the Universe - the conversation of momentum as articulated in Newtonian physics.

 

Before Newton and Galileo Aristotle's physics was grounded on natures and causes. Whenever something moved there had to be a mover.  When it stopped it was because the mover gave up.  There were four elements- air, fire, water and earth.  Earth and water's nature was moving down, air and fire went up.  All transformations had some underlying cause.  Push a cup on your desk and it moves.  Stop pushing and it stops.   The conservation of momentum would say give it a push and it starts moving until opposed.  In fact friction opposes its motion. For many of the things people did the Aristotle's model was fine - in fact we often think about the world that way.  But look more closely and it fails to predict what's going on. 

 

It would be natural at this point to talk about Newton and the marriage of math to physics as it started to become a science. I'll skip that and move to someone you may or may not be aware of - Laplace.

 

Pierre-Simon Laplace came about a century after Newton.  Newton was deeply religious, but his God was not as interventionist as earlier thinking required.  God created Heaven and Earth and started everything moving.  Then, thanks to the conversation of momentum, simple things like the motion of the planets went on without any intervention.  He noted there might be some problems every  once and awhile that would demand attention, but God could kick back and do other things.

 

Laplace was probably the first person to understand Newtonian physics at a deep level - certainly much deeper than Newton.  As he advanced the math and physics he had a remarkable insight.  He knew how to answer the question "what determines what happens next?"  The answer appears to be more philosophy than physics, but it's deeply rooted in the later.   It's also simple - "the state of the universe precisely now."

 

Many see this as a contradiction to free will, but it applies to systems simple enough that we have enough information about them.  That happens to include a lot of fundamental physics.   Biology and sociology are far too complex for us to deal with exactly.  Classical physics is, at its core, non-teleological.  What happens is not determined by final goals or causes.  In fact we don't have to know about the past either - just the now.  The fly in the ointment is you have to know a lot of information.  All the relevant information for every point in the Universe.  This led to the idea of fields being important - information attached to every point - which is at the foundation of modern physics. 

 

This insight is often called the conservative of information.  Words are loaded and easily misused out of context and this is a very specialized.  It's the exact state of everything at a given instant of time.  Conservation implies the information that exists is exactly what is needed to determine the next moment allowing you to move ahead in time. 

 

The conservation of momentum and information are deep ideas with an enormous impact on how we think about Nature and all of physics, not to mention the technological byproducts that have changed how we live.  All of this was set in motion by understanding physics - the study of  matter and motion - can be stripped down to a bare simplicity if you're sufficiently clever.  

 

This way of thinking - stripping down to simple enough - is part of the playfulness of the sport. The approach can be useful in some other areas, but only if you have a handle on local limitations.