A cluster of galaxies, each with millions, or billions or trillions of stars. This ridiculously awesome image (think about it) was taken by the Hubble Space Telescope (via Space Telescope).
The galaxy cluster MACS J1206. Galaxy clusters like these have enormous mass, and their gravity is powerful enough to visibly bend the path of light, somewhat like a magnifying glass.
These so-called lensing clusters are useful tools for studying very distant objects, because this lens-like behaviour amplifies the light from faraway galaxies in the background. They also contribute to a range of topics in cosmology, as the precise nature of the lensed images encapsulates information about the properties of spacetime and the expansion of the cosmos.
Uncomfortable sleeping arrangements of the (simulated) slum.
One of the highlights of the Heifer Ranch trip was the chance for students to spend a night in their global village. It’s really a set of villages, each simulating a life in an under-developed part of a different developing country.
The Thai village. Everyone wanted to end up in the Thai village.
The Guatemalan house is pretty nice; it keeps you out of the elements, you have actual beds, and running water. The Thai houses are actually pretty awesome. They stand on stilts next to the open fields, giving good air circulation and elegant views. They remind me a lot of some of the older houses from where I grew up. The refugee camp, on the other hand is pretty decrepit. The slums aren’t much better but at least have one house with a wooden floor, though the door was so broken it was pretty useless.
Our students were assigned villages at random, but varying numbers were placed in each village to replicate the population densities more accurately. One adult was assigned to each village. We were supposed to act as if we were incompetent (not hard I know), either as two-year-olds or senile elders.
I ended up in the high population slums.
A dragonfly sits on the hard ground in the slums.
On the positive side, I was not the only adult there. Mrs H., who had joined our group with her daughter for the week of activities at Heifer, was also assigned to the slums. On the negative side, she and the girls commandeered the one “posh” building that had an actual floor to sleep on. The boys and I had to sleep on the hard, stony ground.
It didn’t help that one of the boys was “pregnant”. One person in each group been given a water balloon in a sling and told to keep it with them, safe, until dinner, when they would “give birth”, at which point the others in the “family” could help take care of the “child”. A key objective was for the child to survive until morning.
The boys scouted all the houses in the village and scavenged a large piece of metal grating to sleep on. It was not great, but it was doable. Better, at least, than the concrete-hard, uneven ground.
Making dinner over an open fire in the simulated slum.
There was a lot more that happened on that night. None of the groups was given enough to be comfortable on their own. There was a lot of haggling, trading and even commando raids, but, in the end, they pulled together and made something of it.
The experience was quite useful, I think. Conditions were uncomfortable enough to register with the students, though a single night is not enough to really internalize all the challenges of urban slums where over one billion people spend their lives. But it does provide some very useful context for the poignant images of Jonas Bendiksen (Living in the Slums) and James Mollison (Where Children Sleep).
Image from the book, Where Children Sleep by James Mollison.
In my last physics exam, I asked how many bananas would it take to deliver a fatal dose of radiation. This question came up when we were discussing different types of radiation and looking at this graph. One banana gives you about 0.1 microSieverts, while the usually fatal dosage is about 4 Sieverts. That means 4 million bananas. Michael Blastland uses the instantly fatal dosage of 8 Sieverts to make his estimate of eight million.
Usually Fatal Dose: 4 S.
My students were insistent, “Would eating four million bananas really kill you with radiation?”
My answer was, “Yes. But other problems might arise if you try to eat four million bananas.”
Most power plants create electricity by spinning a magnet while it’s inside a coil of wire. That how coal power plants do it, it’s how hydroelectric power plants do it, it’s how wind plants do it, it’s even how nuclear power plants do it; solar power panels don’t do it this way, however. The coal and nuclear plants, for example, boil water to create steam which spins the turbine that rotates the magnet.
In theory, you can use any type of power source to spin the turbine, including people power. On bicycles, you can use them to power your lights. But because you’re now using some of your mechanical energy to create electricity, it will slow you down a bit. Newer, hub dynamos, however, are apparently quite efficient.
So, in theory, you could use any type of animal to generate electricity. Including, for example, using bugs to charge your iPod.
I love how he holds up the voltmeter 34 seconds into the video to prove that his device works.
The first few mornings at Heifer were cold. About five or six degrees Celcius (in the 40’s Fahrenheit) at sunrise. The large barn we slept in had been “converted” from housing horses to housing people. Apparently, horses prefer wide-open, drafty places.
But a warm sleeping bag goes a long way. And being forced to wake up just before the break of dawn does have certain advantages. I’m rarely up and about in time to capture the morning light. With the early morning fog drifting across the slopes and rising off the lake, those first few mornings were wonderful for photography.
Sunrise is usually the coldest time of day. After all, the Sun’s been down all night, and is only just about to start warming things up again. Cold air can’t hold as much moisture (water vapor) as warm air, so as the air cools down overnight the relative humidity gets higher and higher until it can’t hold any more – that’s called saturation humidity; 100% relative humidity. Then, when the air is saturated with water vapor, if it cools down just a little more, water droplets will start to form. The cooler it gets the more water is squeezed out of the air. Water vapor in the air is invisible, but the water droplets are what we see as fog. Clouds are big collections of water droplets too; clumps of fog in the sky.
Tarantula encountered on the path between the Zambia and Thailand (at the Heifer International Global Village).
We ran into this young tarantula on the path between the Zambian and Thai houses in Heifer International’s global village in Arkansas. We were taking the tour, and while this young fellow (probably male according to Zaq our guide) was not part of the regular schedule, we were lucky to find him. While tarantulas are venomous (mildly), and some have stinging hairs, their bites are about as painful as a bee sting (Warriner, 2011). But they are large, and, since most of us have a visceral fear of large arachnids, they’re pretty awesome to encounter (charismatic megafauna – is the term I like to use).
Zaq branished the wooden Spoon of Silence and shouted, "Hey. Take a look at this."
Tarantulas arrived in Arkansas about 8000 years ago (Warriner, 2011) at the height of the warmer, drier climate that followed the melting of the great North American glaciers about 10,000 years ago. The climate of Arkansas has gotten a bit wetter since then, but the spiders survive in isolated, drier upland areas (according to the Arkansas Tarantula Survey), like bits of grassland surrounded by forest. Pretty much like the grassy slope between the Thai and Zambian houses in the global village.
They can live to be 10-20 years old, which I think is pretty impressive for a spider.
Tarantulas usually just hang out at the mouth of their burrow and ambush anything that looks like prey to them. This includes insects and other spiders, but sometimes even lizards and very small mammals.
Identifying tarantula species is apparently difficult because their differences are usually quite subtle. The Arkansas chocolate tarantula (Aphonopelma hentzi), “is presumed to be Arkansas’ only tarantula species” (Barnes, 2002).
If you annoy them (with something like the Wooden Spoon of Silence) tarantulas will rear up and look menacing. Which is pretty awesome.
Page 1 of my notes: Diagram of our mysterious mixture.Sealed jar with a number of unknown substances.
The middle school started science this week with a mysterious jar of unknown substances: a couple immiscible liquids; some plastics and metals of different densities.
As they try to separate and identify the mixture they’ll be learning about handling potentially hazardous materials, material physical and chemical properties (like density and pH), and a little chemistry.
But the first thing they need to learn is how to take notes. Science starts (and ends) with observation. Careful observation. And most middle schoolers need mentoring to make sure their notes are rigorous.
To this end, after they wrote up their observations of what was in the jar, I put together my own notes as a general reference. This is not the only way to take notes, but I’m going to have them amend their own notes to make sure they’re neater and have as much detail as possible.
Page 2 of notes on the mysterious jar.Page 3 of notes on the mysterious jar.
When students are able to recognize mistakes and analyze them, they will learn faster and deeper. Jonah Lehrer summarizes a new study that shows that people learn faster when they spend the effort to learn from their mistakes.
When people notice that they’ve made an error, they have an instinctive negative reaction. Then we have the choice to either ignore the error or spend some time considering it – and learning from it. Guess who learn faster?
This research is based on Carol Dweck’s work on mindset, which shows that it’s better to praise effort rather than intelligence. A willingness to work hard (grit) is a much better attitude for learners. It turns failures into learning experiences, while focusing on intelligence actually discourages people from trying things at which they might fail.
… people learn how to get it right by getting it wrong again and again. Education isn’t magic. Education is the wisdom wrung from failure.
