omenti

is it climate change?

We're sort of ready for Sandy - the combination of three storms that is currently threatening our area.  A quick check of my email found several people wondering if this is caused by global warming.  

 

Of course the stock answer is that you can't state with any certainty that a particular weather event is "caused" by a shift in the climate.  We do know with a very high degree of certainty that global warming is underway and there is a serious piece of it that is caused by the greenhouse gases that come from our burning of fossil fuels.  There are many unknowns - exact mechanisms, the location dependence of future weather events, the location of micro climates, the response of the ecosystem and of human institutions and so on.  That makes it a rich, if somewhat terrifying, field of study.

 

Greenhouse gases are a good thing.  A simple calculation of the Earth's mean temperature without them gives up a bit below 0°F rather than the current figure of about 59°F.   The Earth would be an icy place and life as we know it impossible.  But you can have too much of a good thing.  Life has a very complex set of interdependencies and is finely tuned to local environment including climate.  Over time the planet's temperature has moved around, but these changes have been slow and evolution and a large number of extinctions of species that couldn't hack it have given us our current world.  What exists now is a very swift change - the speed turns out to be much more important than the amount ...  but that is a lengthy subject and I meant to comment on how much of the unusual weather event bearing down on the Northeastern US may be from our hands.

 

One of the best analogies is that of a baseball player who uses steroids.  I've been using it for some time¹...  rather than me writing a few paragraphs here is a video featuring Jerry Meehl of the National Center of Atmospheric Research.

 

So the mean of distribution of extreme weather events if shifted to the right.  There is a lot of fundamental science behind this.  One of the major drivers is the extra energy from the warmer climate.  It turns out it is mostly stored in the ocean and one of the consequences of a warmer body of water is an increased amount of water vapor in the atmosphere.  In fact the roughly 1°C increase in temperature we've seen in the past century has increased the amount of water vapor by about seven percent and most of that has come in the past thirty years.  This means there is much more water available for precipitation.²  This translates into much stronger storms, although it doesn't necessarily mean more of them.  It turns out it has a tendency to make wet areas wetter and dry areas dryer.  We're currently in a phase where many of these effects are relatively linear, but we're beginning to see a few non-linear events that will probably make extreme weather even more common and could increase the rate of temperature change.3

 

Let's get back to the simple explanation of what a shifting distribution means.  I fired up Mathematica to make a few plots.  The first shows two gaussian distributions with a mean of 0 and standard deviations of 1.5 and 2.2.  Probability is plotted on the vertical axis and the horizontal axis is whatever you are measuring.  These simply give you the probability that a measurement of something that has a gaussian distribution is at a certain value.  Notice that the variation increases as the standard deviation increases.  You might think of a thermometer in your back yard and another in your house.  The variation of measurements in your house is going to be small - probably within a few degrees over the course of a year.  The variation outside your house (unless you live in San Diego:-) will be much larger.  Notice that as the variation gets larger the plot lowers.

 

 

The second plot has two gaussians with the same standard deviation (1.5), but with different mean values - one is centered at 0 and the other at 1.  One effect of global warming is that it shifts the mean temperature. If temperature drives extreme weather events you can expect to find more of them.  Also note that a shift of 1°C over the past century took us from 58° to 59°F ...  there are still many opportunities for cold weather events and if precipitation, which is now more likely to happen in large amounts given the additional water vapor in the atmosphere, happens when it is below freezing we get larger snow storms (on average).

 

Moving on to the third graph we have one gaussian with a narrow standard deviation and the other that not only has a larger variation in measurements, but is shifted a unit to the right.  Notice that the probability of events at the left are larger than the first case in the shifted broader distribution and is much higher on the right side.  It turns out this is what we are currently seeing in our weather system.  The climate models suggest greater variation and a shift and we are measuring just that in our changing weather.   The forth graph just shows all three distributions - the shift from the blue to the green distribution is a qualitative view of what is taking place with the climate.

 

Good luck to all of you in the storm's path.  We're going to have to get increasingly good at dealing with the rapidly shifting climate we'll be experiencing over the coming years and decades.  There is a good chance your kids and grandkids are going to witness much more powerful storms than you'll see, so forget about those "when I was young" stories.

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¹ I think the baseball analogy is from Jeff Masters and Tony Broccoli of NCAR...   One of those great illustrations of something that is highly technical made understandable by anyone.  There should be a prize for people who craft these wonderful communications of science.

² Only a rough statement as the system is very complex.  It can change ocean and atmospheric currents and local climates dramatically.  This is the focus of much of the modeling work underway around the world.  

³ One interesting non-linear event is the disappearance of the Arctic ice cap.  When it exists it reflects most of the sunlight that hits it.  Dark sea water, on the other hand, absorbs solar energy and a dramatic shift takes place when the ice disappears.

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Recipe Corner

 

Sweet Potato and Chickpea Salad

 

Ingredients

 

° 2 largish sweet potatoes diced into inch pieces

° 1 can chickpeas (about 15 ounces), drained

° 2 garlic cloves

° 2 scallions chopped

° extra virgin olive oil

° 2 tbl tahini

° zest and juice of 1 lemon

° salt and pepper

° 1 to 2 tbl extra virgin olive oil

° handful of coarsely chopped pecans (toasted if you like)

 

Technique

 

° Preheat oven to 400°F and line a baking sheet with parchment if you want to protect it

° roast the sweet potatoes for about 20 minutes and then turn them over.  Roast until they begin to brown on the surface - about 35 to 40 minutes in my oven

° while the sweet potatoes are roasting, sauté the chickpeas in a pan over medium heat with the garlic and some olive oil until they are dry and warmed throughout.  About three minutes for me. Remove the garlic cloves and reserve them for the dressing.

° To make the dressing chop the garlic finely and mix with the tahini, olive oil  and lemon juice and zest.  Season as necessary with salt and pepper and whatever else you want (I like it just as it is). Set aside

° Combine the finished sweet potatoes and chickpeas in a bowl and toss with the scallions.

° pour the dressing over the veggies, toss, test for seasoning and toss with pecans and serve.  This is best at room temperature.

 

the relationship between civility and doubt

This past Friday I was lucky enough to have share breakfast with Gregg.  I love these meetings as we cover a large amount of space in the hour or so we have and I leave wishing they were more frequent and longer.  Many things come up, but this time he asked why I had given up on the book.

 

Sigh - that has been painful to sort out.  One of my core beliefs over the years is that education is fundamentally important.  Over the past decade I've spent a considerable amount of time and money attempting to deal with global warming, but can only describe the efforts as a learning experience.  The scientific evidence for the problem having a human origin is extremely strong and, silly me, I expected that to be sufficient to spur people into action as the impact of a rapid climate change is potential devastating.  

 

I started to give popular talks on the subject as well as work with some businesses and found that the level of understanding people have about energy is very limited.¹  This isn't surprising as we all have very different backgrounds - I'm sure I can come off as very clueless in deep conversations with many of you.  What did surprise me is that so many people refuse to believe the consensus of experts.²  I initially thought that education was the key and started on a non-technical energy book as most of the books I've looked at didn't provide enough information or were far too technical.  

 

As I'm a poor communicator I managed to conscript a friend into the project.  She served as something of a gauge of the level to aim for and she writes and tells stories better than I can.  We produced a lot of material over a two year period, but it was very difficult to walk the line of what people needed to know and could understand without a more formal background of physics, chemistry, biology and math.  There are a few bits that might fire the imagination a bit and I have used them in talks as well as in this blog and will continue to roll out more over time, but it didn't make sense to us to move forward.

 

I live in a world of confidence levels and probability - I now only have a small amount of confidence that this approach could be effective.  I was beginning to have serious doubts about the role of education in precipitating change.

 

It is striking how uncivil public discourse is on the subject.  Tonight is the last of the Presidential debates.  It is likely that global warming will be almost completely ignored by both sides.  It is impossible to solve a problem without some kind of understanding of mutual positions and reasonable discourse.  

 

How to you begin a civil discussion?  How can we agree to understand what the other side's position is?  Is there a common ground?

 

Six years I participated in a workshop series that tried to mix natural scientists and theologians.  About a half dozen groups formed around the country.  Only one lasted more than three sessions and broke up in bitter disagreement.  The one that lasted was built on a somewhat different foundation.  

 

I started to think about storytelling as not only a part of basic education, but to bring some civility to the discussion. It may take another generation or so to change minds, but a listening process to understand the other side and to recognize the issues of the masses who are unconvinced and unmotivated is necessary.  My education to date has not equipped me well for the task, so I've been listening and learning at the feet of people who make movies, advertise, write children's stories, create art and music and any other non-technical communication that can aim for the heart I can find.  There are a few people who are worried fundamentally about how to communicate science and some of their insight has been very important to me.³

 

Up until about five years ago my belief was that one had to deal with doubt through reason and education.  My own doubt about that old core belief increased to the point where I abandoned several thousand hours of effort and have switched course.  Now I believe civility may be a more important path here and in other major social changes.⁴ 

 

I wish the meeting with Gregg would have been longer as, with his perspective from psychology and technology, there is probably some deep insight that might help me.  So Gregg - next time! I also suspect many of you have important things to say on the subject.

 

It is fascinating that science can have a rapid impact on technology and our standard of living, but the impact on society's core beliefs seems to be much slower ... perhaps lagging by a few centuries.  It is my belief that this is increasingly unhealthy as the impact of technology has become so dominant.  

 

I still believe education is very important, but I'm not clever enough to use it effectively.  I need to begin to talk and learn where the common ground is in the disagreement  I have.

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¹ This is even true among some people who are normally considered technical.  Many computer scientists have much less understanding than a freshman physics major.

² In retrospect this isn't surprising as there is an extremely well funded effort to discredit science and stir up serious doubt.  These efforts invoke laughable "science", but they are extremely effective nonetheless as the audience is not well equipped to sort out the issues.  It has created a huge distraction and that is sufficient to lead to confusion and inaction.  An excellent read on the subject is Merchants of Doubt by Erik Conway and Naomi Oreskes.

³ Folks like Neil deGrasse Tyson and Alan Alda and organizations like RadioLab and the Stony Brook Center for Communicating Science.  There has probably never been a better time with better people working on the problem.

⁴ Gay marriage is an excellent example.  People are enormously uncivil and know the other side is wrong.  It strikes me as though there is an excellent middle ground that would allow some movement forward.

 

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Recipe Corner

 

I recently had need for a celebration and what better way than a cherry pie.  People can be religious about crusts and I won't to into that is this post so I made a quick one with half butter and half vegetable shortening and put together an ugly quick lattice top because a proper cherry pie needs a lattice top and they aren't terribly difficult to make.  So use whatever pie crust you prefer or even thaw out a store-bought double crust and find a 9" pie pan.

Finding proper tart pie cherries in NJ is extremely difficult.  I source mine (canned) from Oregon Fruit Products - the quality is very good and I go through a half dozen cans at least twice a year.

 

Tart Cherry Pie 

 

 

Ingredients

 

Crust

 

° I punted here and won't go into detail as I don't have much time to write.  Eventually I'll post on proper crusts, but don't take my word for it and make your own favorite or buy commercial pie crust dough

 

Filling

° 1-1/4 cups white cane sugar

° 1/4 cup cornstarch

° 1/4 tsp ground cinnamon

° 1/8 tsp un iodized salt

° 6 cups pitted sour cherries

° 1/4 tsp almond extract

 

Technique

° Set oven to 475°F

° in a small bowl whisk together the sugar, cornstarch, cinnamon and salt and set it aside

° put the cherries into a large bowl, add the almond extract and gently mix in the sugar mixture with a spatula

° pour the cherry mix into a dough lined 9" pie pan and then add the top sheet or work on the lattice.

° put the pie on a baking sheet (it can boil over) in the middle of the oven and cut the temperature back to 425° until the pie begins to brown (about 25 minutes).  Now cut the oven to 375° and cook the pie for another 25 to 30 minutes until the crust is a golden brown and the juices are bubbling.

° transfer the pie to a cooling rack and let it cool for a few hours minimum.  During this time think about getting or making some vanilla or vanilla almond ice cream.  (I did vanilla almond and shaved a bit of bittersweet chocolate onto it.)

 

Few things are as wonderful as a fresh homemade cherry pie!

 

literacy in the early 21st century

I  was asked to put together a guest post for the blog of my friend Juliette's organization, the Vibrant Data Project.  I'll write about them later - they're interested in data and our personal rights.  I decided to write a small bit on information and the education we need to be literate in the current age.  It is a rich subject and I have only touched it. 

 

Here is the draft - here it is in the wethedata blog with a more clever title.

 

 

Yuck!

 

The clock told me twenty minutes had gone by, but something was very wrong.  I was expecting the wonderful odor that came with the Maillard reaction - that wonderful dance of chemistry between amino acids and reducing sugars that bring out many of the rich flavors we love in roasting and barbecuing.  The poor sweet potato fries were warm, but the reaction had mostly failed.  How could this be?  

 

I had set the oven for 400°F - hot enough to trigger the reaction, but not so hot as to ruin the expensive olive oil.  A quick check of the oven with an infrared thermometer gave a clue.  Even though the controls told me it was regulating at 400°, it was only 310° around the measuring probe and 280°F on the pan.  I cranked the oven to 550° and watched it like a hawk so I wouldn’t burn my fries.  In the end they weren’t great and I ordered a new temperature sensor for the oven with overnight delivery.

 

There is a common notion that suggests a progression from data to information to knowledge and finally to wisdom.  The “data” in this case would have been the temperature reading on the oven, the signal that it was regulating and the cooking time.  In fact there was some hidden information - namely the oven had stopped measuring temperature accurately enough for my purposes.  The “data” had additional information attached.  I didn’t have a rich enough understanding of this simple system when I closed the oven door.

 

My sport is physics - the simplest and most basic science.  The idea is you watch Nature and ask very carefully phrased questions and by observation and experimentation you get an answer.  You may not like what she is telling you, but if you were very careful at all steps of the process and asked a clean enough question, someone else will be able to repeat what you did - often using a somewhat different path to get at the same question and, mirabile dictu, they get the same response.  Getting all of the bits right can be fantastically difficult.  You have to question everything you do as it is very easy to fool yourself.  Everything is suspect.  If you must use data, information, knowledge and wisdom perhaps the order should be changed.  You need wisdom to school yourself and acquire the knowledge of the system you are studying so you can categorize and understand enough of the fundamental information sources and manipulations to know if any of the upfront information can be called “data” in your community.

 

None of your measurements will be black or white.  Everything will have something of an error and this turns out to be fundamental. So you don’t fool yourself you calculate the size of these errors.  Multiple measurements mean that you need to understand how to calculate an error for your system - you need to know how these errors propagate through your calculations. And finally you need to publish your result with a confidence level.  This will give other physicists an idea of how good your result is - how well it expresses what Nature has told you.  And what you have said isn’t really taken seriously until others can repeat it.

 

A physicist will use the term “data”, but it is very contextual.  It means that it is information where there is a solid understanding of the process that produced it.  Without this understanding it is just information with the baggage that the additional information that is attached to it is not well understood and could very well be wrong.

 

We’re entering this wonderful period where there is a lot of information online and, through the efforts of organizations and citizens alike, it is rapidly expanding.  Unfortunately the accuracy of large amounts of it is not well understood.  It is very useful - no - it is critical - that those of us who produce and use this information have a basic understanding of its accuracy.  When you mash information up from a variety of sources can you state numerically your confidence level?

 

Some bits of information are relatively straight forward and are generally measured to good enough accuracy for your purpose and others aren’t.  There need to be mechanisms for you to find this out.  

 

Anyone dealing with this sort of information needs to become educated in its manipulation.  I’ve been recommending that a requirement for high school graduation should include a year of probability and statistics.  If you are a bit rusty in this area it is a part of your responsibility as someone who interprets these information streams to learn on your own.  Fortunately it isn’t difficult and good resources exist.  Over the past year I tutored a young woman who only has a high school education, but now she is more adroit at the sport of statistics than many MBAs and computer scientists I’ve worked with over the years.

 

Many organizations worry about buzzword compliance and doing “big data” is something that seems to echo everywhere.  I’ve had the good fortune to examine a few projects and it is immediately clear that some have failed badly as the people who architected and those who use them have a poor understanding of the sources of error and its propagation.  

 

There is great potential out there, but there is also great potential for making an utter fool of yourself and your organization.  Good citizenship in this emerging world demands a new sort of literacy, so if you aren’t there yet I encourage you to cowboy or cowgirl up and learn the language.

 

There is too much else to talk about, but I promised to keep this short but there’s one more thing.

 

The science behind understanding climate change has been excellent.  Bits and pieces of it are simple physics, but much of it is part of a very complex system that is exceedingly difficult to sort out.  Dozens of teams have approached it in their own way and, although individual confidence levels are often not fantastic, one can estimate a global confidence level for the community and it is much better than almost any medical test you can imagine.  

 

Sadly the public is largely illiterate when it comes to understanding this point and any scientist knows enough to not project perfect confidence.  The result has been tragic.  Certain interests have been able to manipulate public opinion and force a political stalemate in some countries during a very critical and leveraging time.  This leads me to something else the information and, in particular, the scientific community needs to understand.

 

Storytelling is something that appears to be fundamentally important to many people.  Scientists, including this author, are terrible storytellers and now that information and science are important elements that feed into policy, things break.  Storytelling can be used for good or for evil.  Those of us who play with information need to gain skills and, perhaps more importantly, partner with those who understand this art.  The stories need to be solid - they have to trace back to a fundamental confidence level - but if you mean to change the world you need to be speaking in the most direct voice.

 

This is a brief introduction that skips much of the detail.  For example people are fantastic pattern recognition engines and tend to find patterns were none exist.  I've touched on it in several earlier posts,  but need to go in much deeper in future posts as apophenia is deeply wired into the human species and is central to how we filter sensory information and perceive the world.¹ I've had a look at a few "big data" operations in the corporate world.  Some appear to well well thought out while some are complete disasters.   Over-determination is common and is often used to support pre-conceived notions.  Visualization often is substituted for rigor - hey - if it looks good, it must be right, eh?

 

Yesterday I was thinking a bit about education upon reading a post by another reader of this group.  It wasn't central to his approach, but I found myself thinking about the Malvina Reynolds classic, Little Boxes.  Rather than hunt through my ancient library I searched for a performance to remind myself of some of the lyrics and found this delightful performance by the Canadian group Walk off the Earth.

A sweet version of Malvina Reynolds' "Little Boxes" by the Canadian Group Walk off the Earth



For completeness here is Malvina who, as Pete Seeger observed, is just like everyone else except she woke up and wrote a new song every morning before breakfast...



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Recipe Corner

 

I love it when a serious organization has a bit of a laugh and dresses it in formal clothing - here the New England Journal of Medicine has a very unscientific piece on one of my favorite treats.  There is real evidence that dark chocolate in small quantities can be very good for you, but this is a great example of passing around low quality information with an inaccurate conclusion that happens to justify what all of us want to see.

 

So for your chocolate urges here is a nice recipe I've been using for years.  It is a riff on a recipe I no longer know the source for.  I currently like to make it with a shortbread crust with chocolate mixed in with the crust, but present an easier version with a standard chocolate wafer cookie based crust.  For bonus points you can top it with shaved bittersweet chocolate.

 

Simple, But Rich Chocolate Cheesecake

 

 

Ingredients

 

Crust

° about two dozen Nabisco Chocolate Wafer Cookies (the 9 ounce package) 

° 1 tablespoon of white cane sugar

° 1/4 cup (a half stick) of butter, melted

 

Filling

° 275 grams high quality 70% bittersweet chocolate chopped.  I have been using Lindt 70% or the large (something under 10 ounce) Scharffen Berger bar.

° 4 eight ounce packages of cream cheese warmed to room temperature

° 275 grams white cane sugar (about 1-1/4c plus 2 tablespoons)

° 30 grams (1/4 cup) unsweetened cocoa powder - Hershey's works well (Hershey's cocoa powder is surprisingly good and inexpensive)

° 4 large eggs

 

Technique

 

Crust

° preheat oven to 350°F and butter a 9" springform pan 

° process the cookies in a food processor until finely ground and blend in the sugar.  Add the butter and process until blended.

° press the crumbs into the bottom, but not the sides of the pan.

° bake until it starts to set - about five minutes

 

Filling

° melt the chopped chocolate in a double boiler - remove the bowl and allow to cool to a point where it is slightly warm, but still pourable.

° in the food processor blend in the cream cheese, sugar and cocoa powder until it is smoothly blended.  Blend in the eggs separately, one at a time.

° Mix in the slightly warm chocolate and pour the filling onto the crust in the springform pan.

° bake at 350°F until the center is just set and starts to appear dry - about an hour for me

° cool for about 10 minutes and run a knife around the edges to loosen the cake.

° refrigerate at least six hours.

 

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¹ Visual and audio apophenia exist and a case can be made for the other senses.

 

 

out of the box viewing

I had a delightful chat with Juliette the other night and fell into talking about astronomy.  The next day I came across an image that is a beautiful representation of this and sent it to her along with a bit of an explanation.  The lead in was we were talking about brown dwarf stars the night before - amazing objects that are borderline stars.  They can be very cold - in fact one has been discovered with a surface temperature a bit lower than your skin temperature!  That makes them approximately difficult to detect and they were theoretical until fairly recently, but very sensitive orbiting infrared detectors now detect them and, as you often learn when stumbling onto a new beach, there are puzzles that we hadn't imagined.   One is there are too many for current theories of stellar formation to explain.  Such a lovely problem.

 

I'm very impressed at how small our access is to the Universe if we just use our five senses.  They have serve us well and most of us get along well without enhancing them, but amazing advances in science have been made when we open up new views of Nature.  For a few hundred years telescopes made the dim bright enough to see and then to photograph, but an enormous explosion of new questions and a deeper conversation with Nature came when we started to look at wavelengths beyond what we normally see.

 

Here is the note I just sent with non-astronomy parts edited out - nothing like killing two birds with one stone.

 

 

I was looking around for some images of brown dwarf starts.  They are about 14 or so times the mass of Jupiter  (Jupiter is about 317x the mass of Earth, so these are about 4400 times the mass of the Earth) and are just perking away with a sustainable fusion reaction -- but barely.  One of the amazing things about nuclear fusion is that it can occur at relatively low temperatures and pressures (on a cosmic scale that is - still very very very high for us!)  - the solar core is about 15 million degrees C, or approximately hot to us.  The density is about 150 g/cm³  (lead is 11.3 grams per cubic cm, gold is 19.3 …  for figure about 10 times higher than the densest things we're used to).  It turns out fusion of the sort we see in the solar core proceeds very very slowly - a good thing as the Sun is about five billion years old and we need it to keep on ticking away.  The power density at the Sun's core - the rate at which energy is produced is about 275 watts per cubic meter …  You metabolize energy at the rate of about 1400 watts per cubic meter, so a volume of solar core your size would *not* give you enough energy to live, even if you were 100% efficient at absorbing it (and we are only in the tenths of a percent efficient at that!)  A lizard has a metabolism about 250 - 300 watts/m³.  This is why controlled nuclear fusion is *really* hard to do on Earth.  To get a reasonable rate - a higher power output - we need much hotter temperatures and higher pressures to encourage the hydrogen atoms to bump into each other a bit harder and a bit more frequently.  Temperatures at least ten times hotter than the Sun's core.  It turns out to be a pretty serious challenge.  

anyway back to brown dwarves ….

The surface temperature of a body determines what frequency of light it radiates.  Our skin temperature is about 35°C and we have a peak at about 9.5 microns.  The frequency range of the output is a micron or so wide, but the peak is pretty strong.  So if a camera is sensitive to wavelengths this long (red light is about 0.7 microns, blue is about 0.4), it can pick up your glowing self.  A problem is lots of other things are emitting at similar temperatures and it is difficult to image something as weak as a very dim star in the deep infrared.  Not to mention our atmosphere strongly absorbs these wavelengths.  The trick is a sensitive infrared camera on an orbiting telescope.  The Hubble has some cameras for this, but the Spitzer telescope goes down to 22 microns and does so with the ability to discriminate different wavelengths - so it responds to different IR "colors" .  We can see them visually by mapping them into colors in our band.  We get digital data back and assign different colors to different wavelengths.

The really dim brown dwarves aren't terribly inspiring, but are neat instances of very serious digital astronomy with enormous amounts of "data" being produced and analyzed (astronomers, physicists and astrophysicists have really helped pioneer the computational aspects of "big data" - ugh - I dislike that terminology!)

But while looking I came across a lovely composite image of MGC 7293 - the Helix nebula in Aquarius.  It is a planetary nebulae about 650 light years ago, so the light we're seeing left the nebula around the year 1560 AD - roughly the time period when Michelangelo died, Queen Elizabeth 1 was crowned and Galileo and Shakespeare were born.  It was a star that exploded as a nova and the expanding remnants of the explosion are illuminated by the white dwarf in the center (it is roughly earth sized, so very dense).  

A spacecraft called GALEX recorded a wavelength range from the ultraviolet to near infrared (0.15 to 2.3 microns)- straddling what we see, and the Spitzer does 3.4 to 4.5 and 8 to 24. Another spacecraft known as WISE does 3.4 to 4.5 microns.  

The white dwarf is a tiny white point at the center of the explosion.  It radiates strongly in the ultraviolet and this lights up the expanding wall of star stuff, which radiates in the infrared.  the color assignments are roughly red is cold, blue is hot…  A lot of the UV light is just reradiated as UV by some of the dust. Near the core there is a wide range of stuff going on - both hot and cold, so it looks purplish with these colors.

but enough of that … it also is very beautiful!  both in image and in the number of questions it gives -  both are really important

 

In the 70s Cargill made pre-satellite use of multispectral imagining.  It turns out that you can look at the reflected light from plants and tell their condition.  They had sophisticated film cameras operating at several wavelengths packed into a business jet that would overfly important crop fields in the Midwestern states.  By analyzing the results they often had a better understanding of crop conditions than the farmers and, more importantly, they had an understanding of the relative condition of crops before anyone else in the markets did.  Now days it is much cheaper to use satellite images

 

Isolating what your camera can record can give you an interesting feeling for your own world.  Simply pop on a filter than only transmits a narrow part of the spectrum and see what you get.  With digital cameras it is even easier - many image processing programs let you do this easily.  There are smartphone apps that do a good job - Hueless is a great little iPhone app that gives black and white images, but has several color filters built in.

 

The next step is to do photography in the near infrared and shortwave ultraviolet.  This gets a bit more complex with digital cameras as many have internal physical filters to prevent this, but it is possible and shortwave UV gives a sense of what many insects and even a few birds see, while IR is just plain fun.  Drop a note if you need any suggestions. 

 

We only have three color receptors that operate over a very narrow band, but even within that there are interesting variations.  The retinas in men and women appear to be similar, but there is a sexual dimorphism in spectral response that occurs in the brain.  Women are much more sensitive to fine gradations in red - something which came as a great relief to me as I'm poor at matching some colors and now I have an excuse.  In particularly they appear to be exquisitely sensitive to fine gradations of red in the skin - particularly in the face.  This correlates with the oxygenation level of the blood and can be an interesting signal  It is a really interesting out of band form of communication that we don't pay much attention to and women tend to be much better at it than men.  It is also something conventional color monitors currently can't handle.  Deeply curious research topics here!

 

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Recipe Corner

 

My grandma King was an expert baker even though her oven was terrible.  She never used standard measurements, which is unusal for a successful baker.  During her final year of life my sister and mother transcribed some of her mental recipes assigning measured values.  She was great with molasses and Fall is a wonderful time for ginger bread and ginger cookies.  So with that ...

 

 

Grandma King's Ginger Bread

 

 

Ingredients

 

° 2-1/4 c AP flour or cake flour (or a mixture)

 

° 1/3 c white can sugar

 

° 1 c dark molasses

 

° 3/4 c hot water

 

° 1/2c shortening

 

° 1 large egg

 

° 1 tsp baking soda

 

° 1 tsp ground ginger

 

° 1 tsp ground cinnamon

 

° 3/4 tsp unionized salt

Technique

° Heat oven to 325°F, grease and flour 9"x9x2 pan (metal).  Oven rack at mid level

 

° Measure all ingredients into a large mixer bowl and blend by hand or in a mixer on low speed for about 30 seconds -- don't over mix & constantly scrape the side of the bowl!

 

° Now beat harder for about 3 minutes (or medium speed) 

 

° pour  in pan and bake until a toothpick comes out clean - about 50 minutes.  Cool on a rack 

 

° serve with whipped cream

Grandma King's Ginger Snaps

Ingredients 

° 3/4c shortening

 

° 1/2 tsp non-iodized salt

 

° 1 c white cane sugar

 

° 1 large egg at room temperature

 

° 4 tbl molasses

 

° 2 c AP flour

 

° 2-1/2 tsp soda

 

° 1 tsp ground ginger

 

° 1 tsp ground cinnamon

 

° 1/2 tsp ground cloves

 

° white cane sugar for rolling

Technique

 

° Heat oven to 300°F, rack in middle and just above that if you are using two pans

 

° mix in order given and roll into walnut sized balls and then roll in a bowl of white sugar

 

° place on a sheet with 2" between and press flat with a glass bottom

 

° bake for 12 to 15 minutes until how you like them

 

These are very good with vanilla or chocolate ice cream between them.   You can roll them in a sheet and use a cookie cutter to make larger ice cream sandwiches

 

pulling your weight

It was 1900 at the Paris Olympics.  The Dutch pair of François Brandt and Roelof Klein had qualified in the coxed pairs, but had lost a race to a French pair.  They came to the conclusion Hermanus Brockmann, their 60 kg cox, was too heavy so they found a young boy in the crowd to do the duty.  The boy weighed 33 kilograms and was light enough that five kilograms of lead had to be attached to the shell to make the rudder properly set in the water.

 

The flying Dutchmen leapt to an early lead but couldn't keep their initial pace.  Halfway into the race the French started their move, but at the finish the Dutch were still ahead - but by less than a meter.  A dramatic race by any measure, but more curious is the fact that the cox disappeared into the crowd never to be awarded his gold medal.¹

 

How important is that dead weight?  In theory a cox aims the boat in the straightest possible line, gives pacing and coaching, and removes the effects of uneven thrust as much as possible.  But he or she also adds to the load. Just how important is that?

 

Before diving in,  I note that I'm going to give a sense of the sort of approximation that is common in the physical sciences during play.  One of my advisors said that a 13 year old kid who starts thinking about what miles per gallon means is left with the conclusion the measure is terrible as it doesn't work well in comparing vehicles (you really want the inverse - gallons per distance), you have someone who may well become a good engineer.  If, on the other hand, the 13 year old says "wow - I can express that as inverse acres!", the kid has physics potential.  

 

In doing very quick calculations to test ideas dimensional analysis is frequently invoked. The kid destined to be a natural scientist would look at the units and note that gallons is a volume or a mass.  Assuming you are using the same liquid in your comparisons - at least liquids of similar densities -  it doesn't matter ... take your pick.  Let's pick volume ..  the dimension of volume is a length cubed -  L³.  Miles are easy - just a length.  So miles per gallon is dimensionally L/L³ or 1/L² - an inverse area.  It could be inverse square meters, inverse square feet, or  ... hey .. inverse acres has a nice rural feel to it.^.2  

 

I needed to do a quick estimate for what is described next and rushed through it in about two minutes at the blackboard using this technique. There have been complaints that some readers find my writing too technical.  It is ok to skip the next section and I'll color the skippable text in blue to make it easy, but I thought it might be interesting for some to see how I play and this can form the basis of a good-enough model for understanding what is going on without extensive calculations and measurements. 

 

So the question is how much does it cost for a racing skull to carry a cox?  Rather than a boat with two rowers let's consider the more general case with N rowers.  A four man boat has twice the power of a two man, but its weight is about twice as much.   Does having twice the engine and almost twice the weight help or hinder?

 

The power the rowers deliver mostly is used to overcome the drag on the hull.  It is

p = f_d * v

where p is power, f_d is the force of drag, and v is the boat's velocity relative to the water

The force of drag is reasonably complex and would require some careful measurements that depend on the shape of the hull and some other factors.  The important thing to realize it is proportional to the wetted area - something that goes as a length squared - and the square of the velocity.³   So 

f_d ∝ L² * v²

the power needed is 

p_d ∝ L² v² * v or L²v³ 

The power to overcome the drag is supplied by N rowers (assuming all are about equally strong).  A racing shell is pretty minimal, but its volume needs to increase to float with the heavier load.  The volume goes as L³ and also is proportional to N, so L ∝ N^1/3.  Getting tricky we substitute and now

p_d ∝ L²v³ ∝ N^2/3v³

getting to the end! ....  We know power supplied is proportional to N so 

N ∝ v³ N^2/3

solving for v we see

v ∝ N^1/9

 

The speed of the boat only increases slightly with an increasing number of rowers.  For those of you who have rejoined us it only increases at the one ninth power of the rowers or N^0.111.   The time is just to the inverse of the speed over similar distances so t ∝N^-1/9. If you look at world record times over similar distances this holds for one to four person coxless skulls reasonably well and is a good enough model for this purpose. 

 

The original question was what is the impact of the cox - the little guy or gal with the rudder and the megaphone?  I did a similar analysis increasing the size of the boat, and thus its drag, by going to N + 1 crew members, but assuming only N are contributing to the power.  I won't go through the reasoning as it takes much more time to type than to think about it, but it is very similar.  The predicted time with a cox, t_cox is:

t_cox ∝ (N + 1)^2/9/N^1/3 

To get something that is easy to think about look at the ratio of cox and coxless times and apply a bit of rearranging

t_cox/t ∝ ((N + 1)/N)^2/9

(N + 1) is always bigger than N, so the cox always slows things down ...  not by a lot and the effect decreases with increasing N.  A two man boat should be about nine percent slower if the weight of the cox is similar to the rowers.  But it isn't.  The Dutch used a kid who was about a third the weight of each rower, so a reasonable guess would be about (2.33/2)^2/9 or something over two percent slower - probably several percent faster than an equal muscled crew with a cox that weighed as much as poor Hermanus Brockmann.

 

You can play with some numbers yourself - assuming the cox is just along for the ride the impact of having one decreases with crew number.   Since races are tight you don't want to race coxed vs uncoxed boats and you don't want a heavy cox.  Hopefully they add more value and perhaps you can get a sense of quantifying that value in real vs expected times.

 

A physics teacher usually doesn't do this sort of manipulation for non-major undergrads, but recommends checking answers by looking at the units - if you are calculating an energy it should have the dimensions of mass times the square of a velocity or ml²/t^{2  -} if your answer has different dimensions, there is no way the calculation can be correct. From there you can see if you have picked the right units.  It can be unfortunate to mix metric and Imperial units.⁴

 

Most of us use abstractions - frequently symbolic abstractions like art - to think about our fields.  They allow us to move quickly and play with the key concepts so we don't get lost in the forest of details.  When necessary it is often possible to do something much more detailed - at least we know how to do it in principle.

 

You could ask me what is the predicted time of a eight man coxed shell and I could give some rough approximations, but building an accurate model would rely on careful measurements.  But if you asked me for a ratio of times when the athletes and boat designs were roughly equivalent - then it is only a couple of minutes worth of calculating. You realize when all the tricky stuff drops out and the fundamental parts of the underlying physics are all readily available - in this case some analysis let us get down to just the number of power producing athletes.

 

You have probably seen Feynman diagrams.  They are really visual short hand abstractions of some very complex physics.  You can create and manipulate them with relative ease and make easy to calculate comparisons even though working through the underlying math can be extremely difficult.  They enable play and play and curiosity are two of the big drivers in the field.  Play greatly illuminates whatever you are working on and I encourage anyone to find the play component of their craft and hone it.

 

But in the experimental phase there has to be enormous caution and the analysis phase combines caution and self criticism.  It is still fun, but calculation short cuts don't apply as much as they did early on in the game.

 

But back to the game at hand.   What is the real value of a cox?  I had originally intended write about reducing the wiggle waggle in the shell's motion that is produced by the fact that there are uneven torques produced by the arrangement of the rowers when you have one oar per person.   Next time or the time after I'll write about suppressing the wiggle waggles.

 

And there is another really important issue in many sports.  Larger people tend to have more muscle, but they are also heavier.  Only a few sports adjust for this and the fact that many don't limits participation at elite levels in many sports to larger people.  But smaller people tend to have higher strength to weight ratios ... and you can't have a Godzilla.

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¹ I came across a brief reference to this reading about rowing history and tried to track down a bit more.  There are numerous references and a starting point is here.

² I don't mean to suggest natural scientists are better or worse than engineers.  You can have amazingly brilliant people in either.  The goals and nature of each of these sports attracts very different personalities and native inclinations.  In the end engineers do much better financially than physicists, so that is in their favor, but physics is great fun if that is your inclination.

³ Force has the units of mass * acceleration or mL/t².  Note that L² * v² is L² * L²/t² or L⁴/t², but m ∝ L³, so we can express the ball of wax as mL/t².  (I'm also using L capitalized as l is difficult to tell from the numeric value of one in this font.)

⁴ The Mars Climate Orbiter was lost at orbit insertion as the ground based computations assumed Imperial units for the retro-rocket thrusters ... specifically pound-seconds.  The spacecraft was constructed and the numeric values were tabulated using metric units of newton-seconds.  This destroyed the craft as it entered the atmosphere at a low altitude.  Nearly $700 million and a lot of potential science quickly went down the drain. 

A similar unit problem put a plane load of people at risk, but a pilot who knew a lot about sailplane flying was in the cockpit and the Gimli Glider became aviation legend.

 

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Recipe Corner

 

A really great snack from canned beans.  All measurements are approximate and don't matter much - just play around!

 

Roasted Garbanzo Beans

 

Ingredients

 

° a can of garbanzo beans

° a tablespoon or two of olive oil

° non-iodized salt

° spice blends - use your imagination.  I have a cajun seasoning that is very good.

Technique

 

° preheat oven to 400°F.

°  Drain the beans in a strainer and rinse with water .  Spread the beans on a paper towel and use another to absorb the excess water and roll the beans around to remove the skins. 

° put the beans on a baking sheet and drizzle olive oil over them making sure they are somewhat evenly coated. Roast for 30 to 45  minutes until the beans are a deep golden brown and crunchy and don't let 'em burn

°  season with salt and spice blend.

 

These are really addictive!  

how's that for wimping out with a quick recipe?