omenti

puzzling symmetries

A mini-post

A friend sent a short video of her seven year old asking about mirrors.  Mirrors were a huge puzzle for me at that age.  They would swap left and right, but not up and down.  How did they know?  You could rotate a mirror, but it was always the left and right swapping.  I worried about it on and off for a few months. My parents couldn't help and my teacher couldn't either.  

 

I won't spell it out as it's a neat problem to think about if you haven't already.  After puzzling about it for a few months and then mostly forgetting about it, I was helping my mother wash the dishes.  Finishing, I pulled off a rubber glove and watched it go inside-out.  Suddenly I had the answer. Without realizing it I had learned a bit about symmetry and I also had the thrill of working out something by myself. It was worth the time I spent befuddled and all of the silly drawings I made. 

 

Later I learned you can ask deeper questions about mirrors and that symmetry was a big thing. I also learned you have to pick your questions - why does a mirror switch left and right, but not top and bottom is one I could work out.  How does a mirror work is seriously more involved, but I'd get there with time and work.   In a way the mirror puzzle was a gateway drug.  What were your gateway questions?  I think they can appear at any age. 

 

 

a few useful energy notes - mini post

Recently I've seen a lot of commentary on energy choices - what makes sense given a variety of constraints.  There's some good information but also a lot of obfuscation and muddled thinking.   I probably should post more in the future, but here's the best high level chart of US energy consumption by source and sector.  If you go in deeper than this you need to read quite a bit to understand the models and assumptions, but this is as clean as it gets in a simple view.  

 

 

Some of the more unusual misdirection is calling out wind as bad due to concrete in construction.  Here are some full lifecycle numbers for various forms of energy production in grams of CO2 emitted per kWH of electricity generated before it hits the transmission infrastructure.

 

coal  (US)     980 (average for US coal types)

coal (China) ~ 1200 (optimistic)

coat (India) ~ 1200 (optimistic) 

natural gas     465 (this does not include GHG from NG leakage in mining)

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for the following embedded carbon is added while the fossil fuel numbers above ignore it. 

nuclear         12

PV                 14 - 40 (many factors here - scale tends to win)

geothermal     20-50

biomass         40-250 (lots of dependancies and assumptions here. Many, myself included, feel it shouldn't be considered renewable)

offshore wind  11 (this is dropping .. the largest turbines in the North Sea are more like 9)

onshore wind   12 (for well-sited large turbines)

 

There are no silver bullets if you want to reduce carbon emissions, but there are many choices that are much better than fossil fuels. 

 

 

a most beautiful storm

Finding a clear dark sky is one of the greatest pleasures I know.  They were common where I grew up.  A ten minute drive from town on a cloudless night would reward you with a beautifully starry sky.   In under an hour you'd be a thousand meters higher in the mountains with a beautiful view of the Milky Way. Unfortunately most of my life has been in areas a lot of light pollution, but  I still go out for events like meteor showers.

 

Comets leave dusty trails as they orbit the Sun.  When the Earth passes through some of these trails tiny specs of once-comet strike the atmosphere at very high speeds and leave a streak across the sky as they burn up.  Many of you have probably seen Perseids as they streak overhead at nearly 60 km/h. It peaks around August 12 and reliably gives about one to two hundred meteors an hour in very dark areas.  Many of them are large and bright enough that suburban viewers often see twenty an hour.  

 

The Leonid shower peaks on November 17.  It's usually not as dramatic as the Perseids and many of us live in regions that are cold and cloudy.  But something special can happen about every 33 to 35 years.  The trail has interacted with Jupiter's orbit and has become quite clumpy.  The clumps are narrow enough that the the Earth moves through them in an hour or two.  If you're lucky enough to be in the right place at the right time and it's clear you may see the show of your lifetime. 

 

As a kid I read about a storm of Leonids that was visible over a narrow band of California and Oregon.  Apparently it was mostly cloudy over the West Coast, but a few people in the Sierras had exceptionally clear skies and there were reports between 5,000 and 10,000 an hour for about an hour.  

 

It was well below freezing and cloudy in New Jersey on the November 17 in 2001.  You don't know where these clumps are and if you'll be the path.  I knew there was a slight chance of a storm and had been up all night, but it was mostly cloudy until about 3am.  Around 4 the storm began. I knew this was it.  I ran back and took my chances waking Sukie.  She isn't exactly a morning person. One the other hand this could be a once in a lifetime event - even if you lived a thousand years.  

 

The sky was partly overcast and ground was covered by a few inches of snow.  To get away from the street lights we walked to a clearing in the woods, but light pollution limited seeing to forth magnitude stars.    The storm intensified and I started recording the meteors in tens rather than one at a time.  At times four or five streaks would be crossing the sky at any moment.   All of this and about a half dozen bright fireballs with the brightest casting a shadow as it broke into several pieces.

 

I probably saw around 2,000 meteors during those ninety minutes. Not that I had much of a sense of time as it seemed to only last a few minutes.  A corrected rate for a dark area would be in the 8,000 to 12,000 range.  Some folks in the Adirondacks had a clear dark sky and reported peak rates exceeding 7,000 per hour.  I didn't go to work that day.

 

The next year saw another Leonid storm about a quarter as intense, but it was mostly over Europe.   Around 2034 or 35 you might get lucky.  Astronomers are learning how to track clumps and better predict times and areas.  

 

there were always roads

I had the pleasure of chatting with and, more importantly, listening to Rhinnon Giddens.  She's become well known for tracing the importance of African Americans in music and, at the same time pointing out origins are complex and probably too complex to disentangle.

 

She's a singer, composer, and a fine claw hammer banjo player.¹  These days the banjo is most associated with the white South.  It turns out it came from the Caribbean with slavery and was almost exclusively a black instrument until the 1830s and 40s when white America started to absorb it. From there you can follow it back to Africa and from there to the middle East.  

 

Here she plays an Appalachian piece with Francesco Turrisi accompanying on  a middle Eastern frame drum.

Oddly enough the Irish bodhrán is a very recent instrument based on frame drums from the Middle East - so it fits.  

 

Many - probably most - of our musical styles have has roots elsewhere.  These ancestors also have roots and interconnections.  Trade created a cultural connection machine that made its presence known to people who had no idea where the influences were coming from.  It doesn't take too many people to show up on another shore something new - what can seem like straight-up magic.   Then culture takes and modifies what it finds as it grows.

 

There is no unique source or single direction.  

 

There were always roads...

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¹ She's also a MacArthur fellow.  Her music is powerful.  You need to listen.

 

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.