omenti

tools and the jobs they do

When I was a teenager consumer grade microwave ovens were beginning to appear.  They were very spendy - much more than a conventional oven - so there was a need to convince people there was a deep need.   They seemed to settle on the microwave as a cook-almost-everything, but do it fast, oven.  A neighbor bought one and ruined expensive cuts of meat and numerous other dishes.  The problem was no one looked into the physics and chemistry of cooking and specifically cooking with one of these beasts.  The worst offense was the fact you couldn't create the conditions for caramelization and the Maillard reaction, but there was a problem that different foods absorbed microwaves differently and they only penetrated an inch or so.  In the end it was a $500 (in 1970 money which works out to about $3,000 today) 700 watt water heater and food defroster.   

 

The trick was realizing what the microwave was good for - reheating food and cooking certain types of frozen food, popping popcorn, and measuring the speed of light - and dropping the price by riding the penetration curve.¹  They're nearly ubiquitous, but no one considers them a chef grade do-it-all tool.  In the end the microwave was just a tool and a very specialized one at that.  Curiously a new food industry was created just to support in and a good deal of food preparation has been outsourced in the name of convenience.   There are times when compromises are made when a tool becomes ubiquitous.  

 

A lot of people are excited by the prospect of 3d printing without much concern of what it is really useful for and how it might move past its present state.  Several articles have appeared comparing it to the sewing machine and suggesting companies should look at what is currently going on in the crafting world.  It probably makes sense to take a quick look at the history of the sewing machine.

 

Apparel and fashion are extremely interesting.  They came of age with the industrial revolution, have rich social and political components, are a huge industry - $240 a year for every person on the planet at this point.  It is also happens to be an industry undergoing enormous change with greater change yet to come.  

 

The sewing machine is  one of the prime enablers of mass produced apparel and it is the only major component that has resisted automation.² Like many innovations there was a long development period - about six decades - and  multiple inventions. The first practical machines offered dramatic improvements speeding up sewing from ten to one hundred times and making the process much more uniform. It became practical to make clothing in the home rather than just mend it.  Unlike the 3d printer, it arrived on the market with a killer job to be done.  Households realized they needed it.   The early Singers happened to be very expensive, but clever marketing and financing campaigns made them a fixture in American households.  

 

The sewing machine didn't appear in a vacuum.  The cotton gin was developed in the late 1790s making industrial scale cotton production practical. This brought slavery back in a huge way creating an enormous cotton production in the Southern states.  About the same time the English launched into the development and perfection of high quality fabric manufacture using power looms largely driven by water or steam power.  By the time the sewing machine arrived on the scene high quality and inexpensive fabric was within the reach of the people who bought sewing machines.

 

Taking a two dimension piece of fabric, cutting it into appropriate shapes in such a way that it will fit someone after the pieces are sewn together is anything but a trivial exercise.  The traditional process, something still used in the bespoke world, was only for extremely skilled people who taken years to learn the tricks of the trade.  As a result clothing for anyone but the wealthy didn't fit very well and tended to be expensive.   Around the mid 1860s  Ebenezer Butternick started selling cardboard patterns for children's and women's clothing.  The innovation that made his fortune was his use of grading - making the patterns in a variety of sizes that scaled from a base size. Using them average sewing machine users could make clothing that was close enough to fitting and skilled users could tailor the final result.  Several competitors appeared on the scene within a decade and women's fashion magazines with ordering information for the latest patterns began to appear.  By the early 1900s Butternick ran the largest publishing plant in the US.  In the 50s they bought a name you've probably heard of - Vogue.   

 

Three elements had come together - desirable and inexpensive materials, a home fabrication machine that could efficiently produce good results with modest skills, and the rapid growth of inexpensive design that could fit a wide range of human sizes and shapes.   Personalized home fabrication took off like wildfire. 

 

As the US emerged from depression and WWII homemade clothing began to drop in popularity.  Commercial clothing was dropping in price to the point where it usually wasn't worth the effort and marketing was improving.  Sewing as a hobby and home business continued on a reduced scale, but sewing skills were now largely used for mending.  Clothing prices started to drop dramatically in the 80s as shipping containers made it practical for third world production and fast low quality disposable fashion emerged.

 

Home sewing is largely a hobby at this point, but it has been making a modest comeback driven by the slow fashion movement that is appearing mostly among millennials.³  This growth has been cited as a model for 3d printing -- I think that is a mistaken notion.  The home sewing machine is a tool - a tool with a well understood purpose and enormous flexibility. It is becoming desirable in some leading edge parts of popular culture and is inexpensive.  Designs are easy to obtain and modify and advanced amateurs can make their own.  The notion of copyright on apparel in the US allows an enormous amount of unencumbered design flexibility.  Wonderful materials - those with the right sensoaesthetic qualities - are available from around the world.  It is possible for amateurs to make pieces that will delight.  

 

We're a  way's off from the delight level in 3d printing - unless you are into 3d action figures, making prototypes or other items where material quality and cost is not terribly important.  3d printing is a very important tool in some niches, but it is just that - nothing more than tool without a clear sense of a general purpose killer job to be done.

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¹ OK - maybe measuring the speed of light with a microwave is unusual.  I set up a demonstration for my physics for premeds course when I was a grad student.  I put chocolate in a microwave oven and ran it for about a minute to produce standing wave melt marks in the chocolate.  Look at the microwaves frequency on the back of the oven, measure the melt marks and calculate the speed of light:-)  They were happy - I had about two pounds of chocolate for twenty students.

² Automated sewing is fairly close after more than thirty years of development.  It may not be adopted quickly as third world sewing not far removed from slave labor is incredibly inexpensive.  

³ Slow fashion is an interesting development.  It is a complex reaction to the direction of commercial fast fashion largely driven by a desire for quality over quantity, environmental concerns, a rejection of uniform-like style dictated by marketing, and clothing that fits.  Over-Dressed by Elizabeth Cline is the best introduction to the subject I've seen.

An interesting weakness of commercial fashion is poor fit.  There is no such thing as an average person.  While we tend to find clothing that has a 'good enough' fit, studies suggest over 70% of women can't find dresses that fit to their size. (meaning there is some aspect of the clothing that would fit better in another size .. or possibly not in any size).  Some adjustments are made, but mostly people put up with the poor fit rather than visit a tailor or having custom fitted clothing made.  No one has cracked this yet - a glaring problem that will eventually be addressed.

There are several relevant posts in this blog - sort under fashion and skim if you like.  

 

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Music corner

 

I'm still recovering from the flu and making food hasn't been a central part of my life.  But while walking at dawn on a glorious Spring morning I thought about Mendelssohn's Overture to 'A Midsummer Night's Dream' op.20   When people think of Mendelssohn they tend to think of a certain piece of music used in weddings from a piece with a similar title.  It turns out that came nearly 20 years later.  Mendelssohn was 17 when he wrote the Overture.  

 

The quality isn't great with youtube's compression, but you get the idea.  If you like it and don't have a copy there are several excellent versions 

Seventeen - how many people do you know who had were up to their opus 21 with several serious pieces under their belt by then?

 

A bit over a decade ago I spent quite a bit of time at the Oberlin Conservatory.  One of the delights was dropping in on students and watching them play.  One of the all time fun pieces for string players is Mendelssohn's Octet.  

The performance is good here - I Musici is a quality ensemble - but the youtube quality leaves a lot to be desired.  Still - some pure joy lurks.

Oh - Mendelssohn was 16 when he wrote this one.

 

the wild heart and good vibrations

You might say I was strongly attracted to magnets as a kid.  Such a puzzle ..  they were attracted to the refrigerator, but not to a piece of paper.  I could put several sheets of paper between one and the refrigerator and it was still attracted.  Two magnets, depending on their orientation, would either attract or repel each others. What bothered me most was how did action at a distance work -  how did the magnet know that there was a refrigerator nearby?  Were they talking somehow?

 

My old friend Ge Molin would say that you had to be very ambitious when trying to understand a problem.  For him  野心 meant ambitious and translates as 'wild heart'.  You had to be ambitious to make any progress.  Molin would say you are driven by a wild heat. How wonderfully poetic even if it isn't the most accurate translation.¹

 

Newton's law of gravitation was one of the most dramatic leaps in science .  Two bodies attract each other with a force proportional to the product of their masses divided by the square of their separation.  Double the mass of one object and the force doubles.  Double the distance and the force drops to a forth of what it was.  This, combined with a little more simple physics allows you to work out how most object move in the world we know.  It is even good enough to go to the moon.  

 

Newton had a simple and beautiful theory that was more accurate than scientists of the day - or for a few centuries to come - could measure and it was predictive.  For some it seemed to be the description of Nature at a deep level, but Newton was troubled.  His wild heart thinking made him consider its implications.  The sort of thinking that drives science and progress

 

While it was easy to calculate the forces between two bodies, the mechanism wasn't clear.  How did an apple know how to follow the most direct path to the Earth?  How did the moon know to follow the path it followed - a path that was predicted by mathematics?  The bodies had to sense each others position and mass instantly.  Not only that, they needed to know the position and mass of every other object in the Universe instantly if you really wanted to get things right.  Newton left the problem for those with more insight, but that is a problem with some bits of insight.  His theory allowed people to make predications good enough to change the world, didn't shed light on the inner workings.    There were parts of Newton's puzzlement were similar to what had bothered me as a kid...

  

You're probably wondering why I'm starting with something as well known as Newton's Law of Gravity...

 

Earlier this week two regular readers wrote asking for comments on the announcement of a new experiment that would "create" matter from pure light.  The description given in news reports wasn't very clear and it brings up a deeper question:  what are particles made of?  Thinking about this I couldn't think of a clear way to describe what was going one using the New York Times level physics that most people have.  A practicing physicist uses a different model to think about the process.   Electromagnetism and gravity, although very different, turn out give some insight.  Strap in and I'll try to sketch out some "modern" 20th century physics using a bit of the history of science rather than math.²

 

But back to gravity...

 

In 1783 Pierre-Simon Laplace solved Newton's puzzle.  Rather than try to change the inverse square law he rewrote it to describe a field that filled space with the force of gravity just being the slope of the field.   Fine - what's a field?  Think about temperature.  Every point in space has a temperature associated with it.  The temperature in your room is a field - every point in space has a value associated with it.³ 

 

Imagine a mass like the Earth.  Plot the distance from the Earth on the horizontal axis and the gravitational potential vertically.  The closer you get to the Earth, the more the slope increases and the force due to gravity is higher.  

 

This was a wickedly beautiful solution.  Now you only needed to know the field immediately around the area you were calculating - no longer did you need to consider the mass and position of every object in the Universe.  The spooky action at a distance went away - all of the action is embedded in the field.  The field is a thing - it is a fundamental element of Nature.

 

The 19^th century saw the brilliant unification of electricity and magnetism by Maxwell.  This is another field theory - space is filled with an electro-magnetic field and using Maxwell's equations it is possible to work out a good deal of what our modern world is based on.  The view that emerged was one where matter was made of tiny particles and forces are carried by the gravitational and electromagnetic fields that fill space.  Conceptually a lot of beginning physics and much of engineering is  taught that way to this day.

 

By the early 1930s quantum mechanics had emerged.  It basically states what you observe differs from reality.  In classical physics a particle has a position and a velocity.  Conceptually you could measure these together to whatever accuracy your apparatus allowed as they are real.   You can't measure the position and velocity of a particle to arbitrary accuracy - in fact it is worse than that - there is no such thing as a position and velocity for the particle. What exists is a wave function - a wave spread through space that gives us the answer to what is the probability that you can measure the position of a particle if that's what you want to measure.   At tiny scales - the size of an atom and below -  this is important, but it is more difficult to see as objects increase in size.  What we perceive with our senses is so enormous compared to the quantum world that we don't notice it.  But it is real and is highly predicative and has astonishing accuracy.

 

A more accurate description of Nature is that particles are really just fields.  The combination of quantum mechanics and field theory gives quantum field theory.  It is one of the core tools - probably the core tool - of physics.  Perhaps because it isn't terribly intuitive and requires some mathematical sophistication it usually isn't taught until the junior or senior year of college and rarely outside of physics departments.

 

QFT is very elegant - now you can describe the interactions between particles and particles or particles and fields as fields interacting with fields.  It is a bit of handwaving, but the energy of a particle is related to the frequency of its wave function.  Massive particles have very short wavelengths and are mostly "localized".  At our scale it is easy to mistake it for a very small mass and one that interacts with the gravitational force as well as one of the other three forces in physics.  When you sit on a chair your atoms don't really physically contact those in the chair - the electric repulsion of the electrons that come in close proximity becomes so great that it gives a nice solid surface - a surface that, at a tiny scale, is really the result of the interaction of fields.

 

That's it - at Nature's core (at least to our current understanding) everything is just a field (although there are a variety of types of fields).  Mostly we don't have to think in those terms and we use good enough approximations to throw a ball, watch a sunset or listen to some music.  But if you want to get poetic you are an enormous collection of tiny fields - all vibrating away and interacting with each other and the fields of the Universe all with their own music of sorts.

 

Most of the time is nothing wrong with thinking about the world as made up of atoms and recognizing a gravitational and electromagnetic force, but you can move to a different level when you need to think more deeply about what Nature is doing.

 

Now the original question that was posed can be answered.  If a particle and its antiparticle meet they can convert into a couple of photons. Matter becomes light.  About 80 years ago it was predicted that it should be possible to do the reverse - namely to collide two photons and produce two elementary particles that have rest masses.⁴  This is easy to do in the presence of something like an atom, but the probability of the easiest reaction - two photons turning into an electron and a positron - is difficult.   Now an experiment has been proposed that looks very promising - there should be a result within a year.

 

The Science Times level description has two photons colliding and just vanishing in a poof of energy which turns into an electron and positron pair.  The more useful description has two very energetic waves in the electromagnetic field interact with each other with enough energy (waviness or shaking) that the violently shaking shakes another field - this time the field associated with the electron particle - and an electron and positron are created.  If you could bang another particle field hard enough, you would get out some other combination, but even this very low mass pair is going to be very impressive.

 

A final note.  Sometimes a new scientific result causes an old one to be overthrown, but there are times when additional insight is added.  The old theory is not overthrown, but enhanced.  Sometimes the new theories are easier use on questions where the old theories worked well, but sometimes they are much more difficult to use.  You pick what is easy.  For all intents and purposes most of the world is still accurately described by classical physics.  

 

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¹ Mike notes that 'wild heart' has a slightly negative connotation.  The definition that Molin Ge used applies more to ambitious work - Newton's Law of Gravity is one of the most ambitious pieces of physics.

² I'm not a history of science person and only give a rough outline.  Additionally the natural language of science in general and physics in particular is math and words are inadequate.  So this is necessarily very very rough.  Those of you with physics backgrounds may wish to leave ... 

³ This is only for thinking about a field in terms of something familiar.  Temperature is not something that is fundamental, so it isn't a fundamental field.  Also note that fields can vary with time.

⁴ A photon is technically a particle - a particle without a rest mass.  The notion of matter is loosely defined ..  most people think about it as something that is a particle or collection of particles and particles are usually seen has having mass. To stay away from confusion a photon is usually described as a zero rest-mass particle. 

 

 

sensoaesthetics

Imagine a solid that was a better insulator than almost any other solid and that, at the same time had a very low density - getting down to the density of air at sea level.  I was paging through some papers in the latest issue of Nuclear Instruments and Methods and had just run into aerogels for the first time.¹  They seemed amazing and I had to see some for myself.  Unfortunately they were very exotic at the time and that meant I had to figure out how to make a sample.  Fortunately there was serious interest in experimental particle physics community and our group had access to the instrumentation section of Brookhaven National Laboratories - sort of a playground for building exotic detectors and electronics.

 

It took some calls and emails (yes we had email in the late 70s) to groups in Switzerland and Japan, but we managed to get enough of the basic tricks to give it a try.  We ended up writing a few papers on its properties - the fact that its index of refraction was a bit higher than gases, but much lower than liquids and solids made it an interesting candidate for Cherenkov detectors - and, if you could figure out how to lower the cost and increase its stability, it would make a dandy insulation material for homes, refrigerators, electric cars and a thousand other applications.  People are still playing.  It is one of those amazing materials with a few applications that may - or may not - have a serious impact on more common technologies.

 

Playing with materials is something that is expected in physics as much of the apparatus you need to build for an experiment is unique.  I grew up learning how to work with wood and do simple metal work - soldering, bending and a bit of welding.  When I entered grad school it was clear this wasn't enough, so I took a metal working class and learned the basics of how to use milling machines, lathes and a few other tools I never had access to.  Once I demonstrated competency by building a couple of screw clamps (the department was clever - there was always a need for clamps, so the shop qualifier was to build some and donate them to the department) it was time for a more sophisticated project to start to develop my skills.   I went to the library and located a copy of an ancient Popular Science magazine I had first read when I was about 12 or 13.  It had a construction article for a Stirling engine.

 

For some reason the project captivated me as a kid.  I had been trying to sort out how various heat engines worked and the old Stirlings were very unusual and attractive.  I thought it would be neat to use concentrated sunlight from a large mirror as a power source.  The problem for a kid was not having the tools or skills - thinking and dreaming only goes so far..  Now I had a shot at it.

 

Magazines like Popular Science were full of projects aimed at hobbyists of varying skill levels.  Most involved wood working, but every issue had a metal project or two and some were very sophisticated - a retired craftsman showing off his prowess by building a diesel engine smaller than the tip of your thumb or a one eighth scale twelve cylinder Ferrari engine that ran.  The more interesting projects that a competent hobbyist might have a shot at had blueprints you could send away for.  Unfortunately the blueprint service was long out of business by the time I got around to the project - heavens, the issue was much older than I was.  So I drafted my own design based on the article along with a few books on Stirling engines from the Stony Brook engineering library and figured out what types of aluminum, steel and brass I would need.  The only store-bought bits were the SKF ball bearings.  

 

It took a few days of spare time and worked right off the bat.  I got about 30 watts at 1,500 rpm from it.  Not very impressive, but I was happy.  I never got around to the mirror - I used a blow torch as a heat source making this one of the more inefficient engines around.  

 

But it was fun and that was the point.  I like to build things now and again.  A few people confuse that with engineering, but I'm not an engineer.  They would approach the design problem from a different angle and I'm sure it would work better.  None of my projects, apart from experimental apparatus, are serious - it is only fun.  An artifact of the era I'm from.

 

Before the 1970s making or repairing the things in your house was common - a hobby for some, a money-saving necessity for almost everyone.  Most the families I knew had a sewing machine and a wood shop. A few went beyond that basic level.  It wasn't unusual for a teenage girl to make or modify clothing or a boy to tinker with a junker car to learn about the mechanicals.  For many building things was more interesting than television, which was fairly limited in our area, and many people had the basic skills.  Shop and home economics courses in the schools were mandatory - the ability to make as some level was part of education.²

 

Building skills are rarely taught in schools these days.  All of the shops closed long ago in our district.  The same is true for sewing and cooking.  People tend to buy finished goods these days - often poorly made and unrepairable, but very inexpensive.  We buy and discard.  It has been a delight to see the pendulum start to swing back towards the makers.  Magazines like Make and a variety of websites (Adafruit is neat as it is aimed at women) are teaching people how to build projects, sophisticated electronics are making it possible to build relevant kit that appeals these days and new classes of tools; 3D printers, laser cutters and a variety of CNC machines are available.  A few locations - Seattle, Portland, Brooklyn, Minneapolis, San Francisco, and Cambridge come to mind - have sprouted maker spaces ..  locations where people share the cost of a set of tools and build in an environment with a lot of hands-on instruction.  

 

All of this is wonderful, but it isn't happening as rapidly as many would like.  In particular there is a lot of hand-wringing about the slower-than-expected adoption of 3D printing.  Some suggest that the sewing machine should be a model - after all, it was the  first complex standardized technology that was mass marketed. I don't think that gets at the heart of the problem.  The big issue is what Horace would point out - 'what is the job to be done?'  Many advocates see a future where the 3D printer is an appliance that simply builds what you need - saving the need to have a factor fabricate something that would need to be shipped.  At this point that is a very naïve view and you have to worry about the materials problem and the jobs that are accessible in the nearer future.  There are a several issues that need to be tackled.

 

I'm nearing the end of my hour .. I'll continue this in the next day or two writing about why the sewing machine was successful - three separate elements had to come together at the right time after about six decades of not quite good-enough invention and improper timing relative to another set of technologies.  

 

But until then the thought I want to leave on is embodied in the strange title of the post.  Materials are widely varied and incredibly important.  The number of materials that can be used in 3D printers is a very limited at this point.  People who get into making things find these tools just that - tools.  Extremely useful for prototyping and a few parts that aren't terribly constrained by material choice.  Printing is still  expensive relative to most forms of production, but the technique can be used to enhance certain types of production.  If you had enough money to build a proper shop you would buy a 3D printer, but the laser cutter and CNC milling machine are probably going to be much more useful.³ 

 

Going beyond fabrication is design and materials choice.  Most people aren't designers and have to use the work of others, perhaps making small changes.  But for those who design there must be design skills and tools.  I had enough to design a Stirling engine with pencil, paper, straight edge, compass and my old HP35 calculator.  The tools required for 3D printers have a much steeper learning curve and few have the basic design sense to produce useful items even if they can use something like AutoCAD.⁴

 

But a fundamental component is the choice of material. Something that Apple usually nails and something we admire in other products we associate with good design.  The right metal with the right distribution of weight, a type of wood with a grain that you just like to look at and a smooth beveling of the edges that invites touch.  Even the smell of something or the sound of its operation ...  sensoaesthetic design is subtle, but extremely important.  It can elevate a set of components from mainstream to luxury and, if inexpensive enough, can cause issues for competitors.  

 

... to be continued 

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¹ For a grad student in experimental physics some of the articles were science porn.

² They were also sexist. During my junior year one of the girls managed to argue her way into metal shop so she could learn how to weld.

³ A strong recommendation - if you have the slightest interest in how things are made Making It, Manufacturing Technologies for Product Design 2^nd Edition by Chris Lefteri is a wonderful little book.  Very high level, but fascinating,  Mine is completely filled with annotations and is heavily dog eared after just a year.

 ⁴ If you really want to learn about 3D printers, spend time learning how to use the design programs.  You can send the files to quickturn fabrication companies that will give you much better results than any machine you can afford to buy and maintain.  3D printing, for the amateur, is probably best left to a remote service at this point.

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Recipe Corner

 

Just a quick suggestion. Avocados have been good and inexpensive.  One of the best sandwiches I've had in a long time had a filling of one mashed with finely chopped onion, tomato, pickled peperoncini, dried cranberries, pecans and a squirt of lemon or lime juice to slow oxidation of the avocado.  A bit of sea salt (watch the amount as peperocnini is often salty) and freshly ground pepper and between two sheets of toasted rugbrød.  (I'm a big fan of very dense breads ..  the rugbrød is necessarily homemade, but a good enough substitute is a dense commercial German bread like Mestemacher rye or three grain.)

 

free lunches and beautiful inflation

Imagine what it must have been like to look up at a moonless and clear night sky in preindustrial times.  Perhaps a few thousand stars would fill the sky and perhaps you would wonder how far away they were.  Figuring that out has taken a lot of time - the size of the known universe has expanded dramatically and cosmology has moved from the religion and philosophy to the physical sciences.

 

 About a month ago came news of the discovery of primordial gravity waves and the possible confirmation of inflation.  About the same time a poll that measured public attitudes towards statements on medicine and science was published bringing comments on the low levels of science literacy in the US.  While I would agree that science literacy isn't high enough, I found myself wondering what the poll would report if answered by scientists.  Polls depend strongly on how questions are asked - for example:

The universe began 13.8 billion years ago with a big bang 

I would have problems agreeing and would find myself gaming the survey, trying to guess what it is trying to measure.  The age is accurate enough to a single decimal point, but universe did not begin with an explosion of matter into space but rather space itself increases with time. There was a hot big bang, but it wasn't the beginning. And that is going to take a bit of explanation.

 

Einstein had a problem in 1915.  He finally had general relativity, his theory of gravity, but it didn't work for universes that was static.  Accepted wisdom of the day was that the universe was static so he made the common mistake we all make - he didn't question everything.  He changed the theory a bit by adding a term that allowed it to be eternally static. Later he would say it was his greatest mistake.  But someone was willing to see the beauty in the equations and ask the deeper questions.

 

Alexander Friedmann solved the equations for a general case and discovered the solutions changed with time - the universe had to be changing.  Space itself had to be expanding or contracting.  He came to the conclusion the universe was expanding.  He had discovered, at least in theory, Einstein's general relativity implied an initial state of something infinitely dense - a big bang.¹  Friedman published his work in 1922 - a time when the universe was confined to our galaxy and expansion didn't apply.  There was no observational verification so it was mostly forgotten.

 

A fundamental discovery made the observable universe much bigger.  Edwin Hubble discovered galaxies like Andromeda were external to the Milky Way and distant on a pervasively unimaginable scale.  Specifically he discovered the distance of a galaxy was related to its velocity - the further away something is, the faster it moves.  The notion of what the universe was had fundamentally changed.

 

You would think scientists would be tripping over each other working out where things came from, but that wasn't in fashion at the time - the field was very small and everyone had their own interests. Most of the work concentrated on fleshing out Hubble's discovery.  But just after WWII George Gamow considered the implications of a compressing  universe that was mostly hydrogen. The gas would compress getting hotter and hotter until the electrons were stripped from the hydrogen atoms.  The resulting plasma would be about as hot as the surface of the Sun and opaque.  Turning time around and considering Friedman's model you could imagine a hot big bang that expanded cooling to the point where this plasma ball turned back into hydrogen atoms complete with their electrons and the universe became transparent expanding and cooling as time went on.  The important feature was that there would be a glow from this period - one that could be detected as a radiation spread throughout the universe.  Fifty years ago Penzias and Wilson discovered that afterglow in their work at Bell Labs and the hot big bang had been confirmed.  

 

It was possible to work out a lot of physics.  The first few minutes after the big bang had such a high density and temperature that a few elements were forged - hydrogen, helium and lithium.  Gravity caused the cooling gas to collect in great clouds forming stars and large groups of these clouds and stars formed galaxies. Lot and lots of detail that you'll find elsewhere.² The Friedmann/Gamow/everyone-else big bang is a spectacular achievement of the human mind.

 

but there were a few nagging problems...

 

Without getting technical one problem, known as the horizon problem,  is we would expect a much larger differences in the temperatures observed in the cooling plasma that became transparent about 400,000 years after the big bang.  Another class of problem is the flatness problem.  Again it gets technical, but a Friedman big bang implies an early density that has to be very accurate.  If you look at the density a billionth of a second after the event the number has to be accurate to 24 decimal places. A difference of 0.000000000000000000000001 either way will cause the universe to collapse after a few hundred million years or less, or to expand so much that galaxies and stars would never have formed.  And a few other somewhat more technical issue along with the big one of not knowing how the hot big bang worked.   Not very satisfying to say the least.

 

The solution that may work is astounding and conceptually simple, although it is a bit mind wobbling. There are several heroes - if the results are confirmed, and that is always a big if in science, you'll hear their names read in Sweden.

 

Imagine a volume of air that weighs a gram.  If you double its volume, assuming no new air has been added, its density halves.  Keep doubling the volume and the density rapidly drops to nearly zero.  But what if we had something that didn't dilute - what if we doubled its volume and the density remained the same?  It turns out Einstein's equations  allow such a process.  Guth proposed a very rapid doubling very early on in the age of the universe.  It began with a very small amount of mass and volume doubling once every hundredth of a trillionth of a trillionth of a trillionth of a second (10^-38 seconds per doubling) and going through something like 260 such doublings to create all of the mass in the known universe.  It started out very small with a tiny mass and a size much smaller than the smallest known fundamental particle and stopped leaving the mass of the universe that was on the order of a centimeter across - think the size of a small grape.  As the initial inflation stopped, the tiny universe heated dramatically and the hot big bang proceeded ultimately leading to the creation of - well - everything we see.

 

In a short time I can't go into why the nagging problems were solved.  Rather a bit of insight into what appears to be the ultimate free lunch.

 

OK - I lied when I said I wouldn't write an equation, but you've all seen it:  E = mc². It falls out nicely from special relativity.  You can increase the mass of something by adding energy to it.³  Charge a battery or stretch a rubber band and its mass will increase by a tiny amount.  Release some energy and its mass reduces.  The effect is not huge in our normal experience - adding 25 kilowatt-hours of energy, any form of energy, to a system increases its mass by a microgram - but we notice it with considerable drama in nuclear reactions.

 

Gravity is an attractive force, but general relativity doesn't talk just about mass and gravity - it also talks about pressure.  In general relativity a positive pressure causes an attractive gravity.  A gas has positive pressure - you have to supply energy to compress it.  A rubber band, on the other hand, has negative pressure - you have to add energy to stretch it.  An inflating substance has a large negative pressure.  The energy required to expand our uniform density bog to twice its volume is just enough to double its mass.

 

Guth found the repulsive gravitational force caused by the negative pressure was about three times stronger than the attractive force caused by the mass, so the net gravity in an inflating object causes it to keep inflating.  So the inflating blob produces an anti-gravity that blows it up and the energy it expends in the process creates just enough new mass to keep the density constant.  The balance of the total energy of the system hasn't changed even though it is now much larger with much more mass.  

 

The ultimate free lunch.

 

Very very strange indeed. Inflation not only solved the nagging problems of the hot big bang, but it provided predictions that can be tested.  One important one was the very strong gravity waves that are seen in the cosmic background radiation bear the imprint of quantum mechanical fluctuations present at the beginning of inflation.⁴  Those fluctuations gave rise to some non-uniformities in the universe which, in turn, allowed gravity to selectively pull areas together forming everything we know.   Those predicted signatures are what were reported last month from the experiment in Antarctica.  We went from knowing about the universe about a minute after the big bang, to a period right at the beginning of the hot big bang and a litle before.  If it holds there are many more new questions - the same is true if it doesn't, but the questions shift.  

 

If it does hold there is an interesting and probably likely possibility that inflation didn't stop - that we might be in pocket universe where inflation stopped with an infinite amount of creation taking place.  The concept of a multiverse is something that demands attention.  

 

We went from the center of the world being our village with the universe not being much farther than a person can travel in their lifetime, to something not much larger than the earth, to one centered around the Sun and perhaps extending to Saturn, to losing the concept of a Sun centered universe, to the Milky Way and then to our current observable universe.  But perhaps reality is much richer than that limit.

 

There is an important lesson that is told over and over again in science.  If something nearly works but has a small set of problems it is often a sign that something deeper and more interesting lurks.  Often these leaps are out of reach, but they are the source of the really earth-shaking changes in how we understand Nature.

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¹ The term big bang was coined by Fred Hoyle in a BBC radio broadcast in the last 40s.  Ironically Hoyle believed in a steady state universe. Skipping over history a bit, Georges Lemaître came up with a similar solution a bit later.  At the time both Lemaître and Friedman were largely ignored.  Some ideas come a bit early and in all fairness there are an enormous number of ideas which never work out.  A hypothesis should make testable predictions in order to being taken seriously.

² A rough summary is there was a hot expanding core about 13.82 billion years ago.  For the first few minutes it was a hot fusion reactor producing about three quarters hydrogen a quarter helium and bits of lithium. Expansion cooled the universe to the point where fusion stopped. Around 380,000 years ago the hot plasma cooled and became transparent.  Radiation from this surface, heavily red-shifted - is the cosmic microwave background - note it is not from the big bang, but a visible artifact of it.  Clumps of matter were pulled together by gravity forming galaxies, solar systems and so on.  Some of the stars supernoved spewing heavier elements into space.  These heavy elements became part of a new generation of solar systems that allowed chemical complexity.  At least one of these had the conditions to allow life to form.

³ E= mc² is the simple form of the equation for energy E and a rest mass m.  There is a deep relation between mass and energy.  A misconception is that mass must be destroyed to produce the energy in a nuclear reaction, but the energy release is just the difference in the masses of the initial and final bits of the reaction. 

A more complete form relates energy, mass and momentum: E² = (mc²)² + (pc²)²..  a lovely short video by MinutePhysics gives a good explanation.

⁴ This may offer important insight into the potential linkage of the quantum mechanics and gravity.

⁵ Common usage of the term implies something speculative.  Anti-science groups exploit this difference to their advantage.

 

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Recipe Corner

 

There are many ways to do split pea soup.  Here is a rough outline of one I made the other day.  A trick for olive oils is unless the flavor is very important, you can get away with something cheap.

 

Split Pea Soup

 

Ingredients

 

° 2 cups split peas

° 1 large stick celery, finely chopped

° 1 medium onion, finely chopped

° 1 cup diced carrots

° 2 tbl olive oil

° 1/3 cup dried barley

° 2 bay leaves

° 1 tel Tamari soy

° 1 to 1-1/2 tsp salt

° black pepper to taste

 

Technique

 

° sauté the onion in olive oil 'til it is transparent in a large pot

° add 8 cups of water and bring it to a boil, add 4 cups of water to a smaller pot and bring it to a boil

° add peas and bay leaves to the large pot and cook until the peas break apart easily - about 45 or 50 minute for me.  Stirring more towards the end

° add the barley to the small pot and cook until tender - about 45 minutes

° cook the carrots in a small pot of salted water until tender, drain and set aside

° when the peas are tender, remove the bay leaves.  Now blend the peas until smooth with an immersion blender or in a blender (I prefer immersion blenders - less chance of spilling disasters).  If you want something a bit chunkier just whisk away as the peas will break apart nicely.

° strain the barley and add to the soup with the carrots and Tamari soy.  Salt and pepper as you like it.