Everything depends on your point of view — more or less. Our picture of the universe has changed in the last 60 years as telescope technology has improved. Popsci has a great interactive visualization showing how much more we can see now.
Notice that in this picture, the Earth is at the center of the universe (the Sun is a little way off to the middle lower left). After all, we’re looking at the universe from the Earth, not the other way around.
Rowan Kaiser asserts that Mort‘s the best place to start to discover the wonderful novels of Terry Pratchett.
the Discworld books combine silliness, satire, philosophy, and strong characterization to create a unique, often wonderful tone that’s more than capable of supporting a series with so many installments. But the number of installments can seem overwhelming, especially given that while the books have standalone narratives, they also have consistent sets of characters who develop over the course of the series, leading to an apparently complicated web of a few different, occasionally overlapping series-within-a-series.
My recommendation would be one of her runner-up gateways — either Guards! Guards! or Wyrd Sisters — but she makes good points. Her third runner-up, Small Gods, which is one of the stand-alone novels is one of my favorites, and was my first Pratchett book. And it got me hooked.
Pratchett’s work is intelligent fantasy, in that it’s a lot like the hard science fiction I prefer. It sets up the rules of its universe and then follows them to their logical conclusions, no matter how absurd.
I often wonder how these books would appeal to adolescents since there’s a distinct possibility that much of the quite enjoyable satire would pass over their heads. The Amazing Maurice and his Educated Rodents won the Carnegie Medal for children/young adults, but while it retains Pratchett’s characteristic style and humor, it was written for a younger demographic, unlike most of his other books. I did get one student to read Small Gods, and her response, with a grimace was, “It made me think“.
visual.ly posts and hosts some excellent graphics. The one below, calculates the nearly infinitesimal probability of just being born. There’s hardly a better argument for appreciating life.
It’s also a good example of working with probabilities [and] exponents. Very large exponents.
C.G.P Grey makes the case against the Electoral College in video form. He starts with how the Electoral College Works and continues with a well reasoned polemic against it: he’s big into democracy — one person, one vote.
Back in the day, if you wanted a non-stick cooking skillet, your best option was to do it yourself by seasoning a cast metal pan. Sheryl Canter has an excellent post describing the science behind the “seasoning” process. The key is to bake on a little bit of oil to create a strong cross-linked polymer surface. This is a nice tie into our discussion of polymers and polymerization in the middle school science class; although I’m not sure how many of my students have actually seen a cast iron pan, or even know what cast iron is.
To season, you coat the pan with a thin layer of oil and bake it for a while (without anything in it). Baking releases free radicals from the metal that react with the oil to create a cross-linked polymer that’s really hard to break down or wear out, and prevent food from sticking to the pan. Different, cross linked polymers are used in car tires for their durability, but probably not for their lack of stickiness.
Apparently, linseed oil is the best seasoning agent, but it might be a bit hard to find.
Most non-stick, artificial surfaces, are also made of polymers of hydrocarbons, silicon oxides and other interesting chemicals.
This research shows that profanity is not harmless. Children exposed to profanity in the media think that such language is ‘normal,’ which may reduce their inhibitions about using profanity themselves. And children who use profanity are more likely to aggress against others.
–Brad Bushman (2011) in a Brigham Young University Press Release.
Exposure to profanity in videogames and on TV appears to affect how teens view and use profanity, and makes them more aggressive. These are the key results of a paper by Sarah Coyne (Coyne et al., 2011). The full article is available online, but is summarized here.
While the first part, at least, of this result might seem obvious — that seeing profanity desensitizes, familiarizes, and leads to increased use — it’s nice to have some scientific corroboration.
The more disturbing result, perhaps, is the link between profanity and aggression. It’s a moderate effect, but the link appears similar to the connection between war games and aggression.
Profanity is kind of like a stepping stone. You don’t go to a movie, hear a bad word, and then go shoot somebody. But when youth both hear and then try profanity out for themselves it can start a downward slide toward more aggressive behavior.
— Sarah Coyne (2011) in a Brigham Young University Press Release.
Sitting in a car that’s going around a sharp bend, its easy to feel like there’s a force pushing you against the side of the car. It’s called the centrifugal force, and while it’s real to you as you rotate with the car, if you look at things from the outside (from a frame of reference that’s not rotating) there’s really no force pushing you outward. The only force is the one keeping you in the car; the force of the side of the car on you. This is the centripetal force. Given all the potential for confusion, I created this little VPython model that mimics a sling.
Centripetal Force
In the model, you launch a ball and it goes off in a straight line. That’s inertia. An object will move in a straight line unless there’s some other force acting on it. When the ball hits the string, it catches and the string starts to pull on the ball, taking it away from its straight line trajectory. The force that pulls the ball away from its original straight path is the centripetal force.
Conservation of Angular Momentum
The ball rotating on the sling has an angular momentum (L) that’s equal to the velocity (v) times its mass (m) times its radius (r) away from the center.
L = mvr , angular momentum
Now, angular momentum is conserved, which means that if you shorten the string, reducing the radius, something else must increase to compensate. Since the mass can’t change, the velocity has to, and the ball speeds up.
I’ve put in a little ball at the end of the string that you can pull on to shorten the radius.
Tangential Velocity
Once the ball is attached to the string, the centripetal force will keep it moving in a circle. If you release the ball then it will fly off in a straight line in whatever direction it was going when you released it. With no forces acting on the ball, inertia says the ball will move in a straight line.
To better illustrate the ball’s motion off a tangent, I put in a target to aim for. It’s off the screen for the normal model view, but if you rotate the scene to look due north you’ll see it.
Alison Gopnik points out the people first start to learn by exploration (the same way scientists do), and then learn to do things well by apprenticeship.
When we actually start to look at the fundamentals, it seems children learn by exploring—by experimenting, playing, drawing inferences …. that kind of exploratory learning isn’t just the purview of scientists but seems to be very, very basic. …The other kind of learning that we see, not so much in preschoolers but in school-age children, is what I call guided apprenticeship learning, where you’re not just exploring and finding out new things but learning to perform a skill particularly well.
Kate Fillion’s great interview with Gopnik, a cognitive scientist, is worth the read.
The traditional way of thinking about learning at a university is: there’s somebody who’s a teacher, who actually has some amount of knowledge, and their job is figuring out a way of communicating that knowledge. That’s literally a medieval model; it comes from the days when there weren’t a lot of printed books around, so someone read the book and explained it to everybody else. That’s our model for what university education, and for that matter high school education, ought to be like. It’s not a model that anybody’s ever found any independent evidence for. [my emphasis]