I’ll write a more interesting post soon, but for now, I present Lawrence Krauss. Here he gives, what I’ve decided to be, the best one hour overview of cosmology I’ve ever seen. (via richarddawkins.net)

What do you all think about his suggestion that getting a universe from nothing is natural?

So, in case you don’t know by now, it’s Blog Action Day 2009… ( or at least, it will be for another half hour. I’m a bit behind the times.)

Blog Action Day is an annual event held every October 15 that unites the world’s bloggers in posting about the same issue on the same day with the aim of sparking discussion around an issue of global importance. Blog Action Day 2009 will be one of the largest-ever social change events on the web.

The topic of choice for this year is: Climate Change. Yes, that scary thing.

I puzzled a while trying to think of something physicsy to tell you about climate change. I could tell you that same story about how CO2 in the atmosphere traps heat causing an increase in average global temperatures. I could tell you that this is exactly the reason why the planet Venus (with a CO2 rich atmosphere), although it is further than the sun from Mercury, is hotter by a long shot. But I decided against repeating those same old stories, because I figure you’ve probably heard them many times and are probably getting numb. Instead I’m going to go outside my comfort zone and plunge into the depths of Limnology and tell you about some current issues involving climate change in the convective currents of holimictic lakes.

…what’s a holimictic lake, you ask?

Good question. I’m not much for fancy names; I prefer concepts. So, let’s start with the basics. Firstly, you must have heard that hot air rises. But why does it do that? Well, air that is hotter than the air surrounding it is also less dense than that air. This means that a volume of hot air weighs less than the same volume of colder air. The colder air will be pulled towards the earth more than hot air and so hotter air will be pushed out of the way (upwards) by colder air.

The same is true for water, but only to a certain degree; 4°C to be exact. Water, unlike air, is densest at 4°C, so in a tub of 5°C water, a 7°C blob of water will tend to rise to the top. On the other hand, in a tub of 1°C water, a 3°C blob of water will tend to sink because even though it’s warmer it is more dense.

Now, consider a lake in the four seasons. During the Summer the lake water is generally above 4°C, so the sun will warm the top layers of the lake and that water (being warmer and less dense) will stay on top and the cooler water will stay deeper down.

When Fall comes around the top part of the lake will be cooled. Eventually that top part of the lake will cool to the same temperature as the bottom part. Winds can cause some turbulence and the bottom parts and top parts of the lake will get mixed up.

When Winter comes along the top part of the lake will be colder than the bottom part which can happen when the lake is lower than 4°C. The top layer of the lake may freeze over and the lake will again get separated into layers of different temperature — this is called stratification.

The lake gets mixed up again when Spring comes around. The top of the lake will be heated again and when the lake water at the top reaches 4°C it will sink to the bottom and mix up the lake.A lake that undergoes this kind of mixing is called a holimictic lake and if it does it twice a year (as described above) it’s called a dimictic lake.

…what does this have to do with climate change, you ask?

Well, nutrients from the lakebed seep into the lower parts of the lake while it’s stratified (Summer and Winter for a dimictic lake). When the lake mixes, these nutrients get mixed into the whole lake. If you are aquatic life which has adapted to depend on those nutrients, this mixing is a very good thing. Without it, many species of fish would not be able to survive in that lake.

Climate change threatens to put a damper on that mixing process for some lakes. As average global temperatures increase, unusually warm Winters become more likely. What would happen to a dimictic lake during one of these unusually warm Winters? Well, the lake won’t cool very much during the Fall, and might even stay above that 4°C mark. This would cause less mixing during the Fall. To make matters worse, because of the warm Winter, there will be less mixing during the Spring as well. To make matters worse still, those salts that are dissolved in the deep parts of the lake make those deep layers more dense. Less mixing during a certain Fall or Spring means more salts stay built up in the deep layers of the lake making it even more difficult to mix the upper and lower layers in future seasons. This is a runaway process and it can lead to a nutrient deficient lake, and very unhappy fish.

The take away message? Climate change isn’t just about things getting warmer and sweating more during the summer. Climate change is a direct threat to whole ecosystems. By tipping ecosystems out of balance it endangers many species of animals, including the animals causing the tipping (us). It’s high time that you start sweating over this situation. Please think about ways to cut your greenhouse gas emissions. If you need some suggestions, here are two good ones.

So, I’ve never heard this myth before, but a friend asked me about it a while ago. The myth states that running in the rain will make you wetter when you arrive at your destination than if you had walked. This was on my mind recently because it was actually a bonus question in the physics lab I’m TAing for this year.

Apparently Mythbusters showed that running is a better option for staying dry, but only after they corrected for a false result they’d obtained in a previous show. So how could you figure this out without going through the hassle (or fun) of running through some rain yourself?

Well, what we could do is set up an idealized situation. Imagine there are 5000 drops of rain falling in every cubic meter above you. Let’s say they fall at 5 m/s straight downwards. To simplify things even further, let’s suppose we ignore the structure of our bodies and just consider a blocky person to have a set width, depth and height. Let’s make up a name for this person; Sponge Bob Square Pants (Bob for short). So, let’s say Bob is 0.25m thick, 0.5m wide, and 1m tall.

If Bob stands in the rain, all of the rain will hit his head. The number of drops hitting him per second is equal to the density of the rain times his width times his height thickness times the velocity of the rain in the downwards direction;

5000 drops/m^3 x 0.25m x 0.5m x 5m/s = 3125 drops/s

If he moves (walks or runs) this amount won’t change because the downward velocity of the rain won’t change with respect to him. But, on the other hand, if Bob walks or runs in the rain, the rain will have a horizontal velocity with respect to him, so the rain will start to hit him in the front. We can find the number of drops hitting his front by the same method.

5000 drops/m^3 x 0.5m x 1m x V = 2500 drops/m x V

I’ve just called Bob’s walking/running speed V. I’ll leave it like that and plug in his speed at the end. If Bob needs to run to his house which is 20m away, a total number of drops of rain will hit him in front and back for the trip which we can calculate. We just need to multiply the above results by the time it takes him to get there and then add them together. That’s just the distance to his house divided by his walking/running speed.

time = 20m/V

But here something funny happens. For the rain hitting his front:

(2500 drops/m x V) x (20m /V) = 2500 drops

Hey! It doesn’t depend on how fast he runs! So it really comes down to the rain hitting his head:

(3125 drops/s) x ( time to get home )…

The faster he runs, the less time it takes him to get home. So to minimize the number of rain drops hitting his head, the faster he needs to run.

… but hey! I’m not the same shape as Sponge Bob, and rain doesn’t always fall straight down, you say?

Well, for those of you who want a more complex analysis, here’s a link to an online running-in-the-rain-wetness calculator. Check it out, it’s fun!

So maybe you’re a non-physicist, who wonders how physicists think. Maybe you aren’t really sure how those crazy physicists come up with all of these equations and theories seemingly from thin air. Maybe you’re getting a bit bored of F=ma posts. Well, I’m going to try my best to give you a bit of an inside look at some of the conceptual tools commonly used by physicists in a little series called: The Physicist’s Toolbox.

This week: Thought Experiments

When someone mentions the term “thought experiment”, the first person that probably comes to mind is Einstein and his daydream about trying to chase a beam of light — an image of which even non-physicists will be familiar. This is because thought experiments tend to be very memorable and accessible because they usually involve simple math or no math at all. Despite their mathematical simplicity, however, they still manage to shed light on puzzling aspects of nature.

Physics is an empirical science which means that you can do all the thinking and theorising you want, but at the end of the day, if it doesn’t match the real world experimental results, it’s wrong. This fact might make the term “thought experiment” seem like a bit of an oxymoron. It’s true, a thought experiment won’t serve to prove anything in the same way a real experiment would, but it still has tremendous value. Thought experiments serve to collect one’s thoughts and attempt to make certain concepts in physics more intuitive. Occasionally they can shed new light on how the world works.

Here’s a really neat example. Remember Galileo? Remember the story of him dropping a cannon ball and a musket ball from the leaning tower to show that they fell at the same rate? Well, it’s unlikely that Galileo actually did this. It’s more likely that this was a well crafted thought experiment. Imagine starting with the assumption that heavier objects fall faster. What happens now if you attach a lighter object to a heavy object? The light object would want to fall slower than the heavy one, and would almost act like a parachute for the heavy one. But if you consider the compound object, it is heavier than both objects alone. So shouldn’t it fall faster? This thought experiment demonstrates that the assumption that heavier objects fall faster leads to a contradiction. An obvious resolution to the contradiction is to declare that all objects, regardless of their weight, fall at the same rate. If one did this experiment in real life would probably not see the objects fall at the same rate because of air friction. The power of the thought experiment is in its simplicity. It serves to demonstrate how nature should behave under certain assumptions and signals that something more is needed to be understood if nature doesn’t behave like this.

Newton’s cannon ball is another great example of an enlightening thought experiment. Really, just the simple picture of a few trajectories of a cannon ball being shot with greater and greater force demonstrates how things like the moon can orbit the earth. Good thought experiments like this tend to give the thinker an “aha!” moment; that moment of realization.

I’ve blogged about a few thought experiments here on Morning Coffee Physics. Some fun ones include Einstein’s elevator experiment, and the Rope and Wood riddle.

There’s one more thought experiment I really like. Imagine placing a chain (constant mass per unit length) on an obtuse triangular block. On one side, there is less chain, but a steeper slope. On the other side, there is more of the chain, but the slope is not too steep. Which way will the chain slide?

Sure, you could work out the forces and angles and all that jazz. But there is a very simple way to see the answer. Think about it for a few seconds.

…

Done? Okay.

Just connect another chain below and let it hang off of the ends of the previous chain, like so. Have you felt that “aha!” moment yet?

The hanging chain is symmetric so it should pull on each side of the top chain equally, which cancels its effect out. But if the top chain slid to one side or the other, for every link that fell off the block, another would replace it on the other side (coming from the hanging chain). Meaning the two (now linked) chains would spontaneously spin around the block! This is a ridiculous notion and a violation of the laws of conservation of energy. Therefore, the chain in the previous picture must remain at rest. No math necessary!

Anyone else have a favorite thought experiment?

___

A great reference: Brown, J. R., “Thought Experiments”.

So maybe you’re a non-physicist, who wonders how physicists think. Maybe you aren’t really sure how those crazy physicists come up with all of these equations and theories seemingly from thin air. Maybe you’re getting a bit bored of F=ma posts¹. Well, I’m going to try my best to give you a bit of an inside look at some of the conceptual tools commonly used by physicists in a little series called: The Physicist’s Toolbox.

This week: Symmetry

Physicists are obsessed with symmetry, perhaps even more than people with an OCD. It’s human nature to look at something symmetric and call it beautiful. Even physicists call their theories and equations beautiful if they contain some kind of symmetry. The aesthetic attraction humans have towards symmetric things is not a surprise to me; the laws of the universe are founded on symmetry. It’s only natural that the things we see every day in our world reflect this symmetric undertone of the universe and we call these things beautiful.

…so what is symmetry, you ask?

You probably have a good idea of what symmetry is by just looking around your everyday life. You probably look in the mirror every morning and notice that our bodies are symmetric. If one draws a vertical line down the center of the human body, the right side is approximately the mirror reflection of the left side. This is called reflectional symmetry but it is one of many types of symmetry.

You can make the idea of symmetry more general by roughly saying that something is symmetric if you do something to it and it stays the same.  The “doing something” part, physicists like to call an operation. This could mean anything; reflection, rotation, translation, magnification, etc. So to be more specific, physicists say that some “thing” is symmetric under a specified operation.

Look at that picture of the square up above, for example. Ignore the colorful dots and just concentrate on the shape. If I rotate the square by any multiple of 90 degrees, it will look exactly the same as if I hadn’t done anything. So you could say that the square has rotational symmetry. The operation here is a rotation by an angle which is a multiple of 90 degrees. So an even better thing to say is that the square is symmetric under rotations by angles of multiples of 90 degrees.

…okay, but what does this have to do with physics, you ask?

This is the cool part. In physics, instead of looking at shapes of things and studying how the shape of something is symmetric under an operation, we go a bit further. We study how the rules of nature stay the same under a certain operation. Let’s look at a concrete example. Let’s say I do a little experiment: drop a ball from some height and time how long it takes to hit the ground. Then I take myself, the ball and the entire earth and move it ten feet to the left (in other words, I preform a translation on the system). Now I redo the same experiment. The ball should take exactly the same time to hit the ground if dropped from the same height. So, the rules of nature are symmetric under translation in space.

Since so many people have heard about Einstein’s Special Relativity, let’s use that as an example too. Einstein postulated that the speed of light is constant for all “inertial” observers. This is a statement of symmetry. It’s saying that if you preform an operation on an observer, the speed of light should stay the same for that observer. The profound insight was that this was even true for operations that changed the speed of the observer. These operations are called Boosts. (Note: I don’t mean acceleration. It’s not the same thing as a boost. I mean this as a mathematical concept.) So, if you consider two different observers, with different (constant) velocities, the speed of a light ray will be the same for each of them. Noticing that the constancy of the speed of light is symmetric under boosts leads to crazy results which you probably already know about (time dilation, length contraction, etc).

In fact, when physicists notice (or impose) types of symmetry in their theories, different laws of physics just fall out of the equations. Some of these are:

• Symmetry under spatial translation gives conservation of momentum
• Symmetry under time translation gives conservation of energy
• Symmetry under boosts gauge transformations gives conservation of charge (I plead temporary insanity)
• … and much more

Symmetry is has become such a useful tool that physicists have come to assume that physics theories should abide by some standard symmetries. This is partly the reason you hear crazy ideas like the world having ten dimensions. String theory starts with the assumption that there are “strings”, it then imposes symmetry arguments and what falls out is: the world has ten dimensions.

But what happens when symmetry breaks and the laws of nature become a bit lopsided? Hey it happens! Nature isn’t a perfectly spherical cow.

That’s when things get even more interesting…
_____
Update: An interesting TED talk on Symmetry.
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1. I shouldn’t even bother with F=ma posts anymore. Rhett at Dot Physics is totally owning everyone with his super interesting classical mechanics posts.

Well now. That was a long lasting spontaneous blog hiatus…

Sorry. It’s not that I’ve run out of ideas, it’s mainly lack of time… well, since time is relative, maybe it’s just that I perceive myself as having less time than I actually do. But enough excuses… let’s get back to the physics.

I saw a really neat (3 page!) article on arXiv today called “Google Earth Physics“. I love google, and I love physics, so naturally I had to check it out. The abstract reads,

Google Earth photographs often show ships and their wakes in great detail. We discuss how the images can be used to calculate the velocity of these ships.

Did someone say, do-it-yourself-physics? I knew I had to post this. Naturally, ZapperZ beat me to it… but I’ll go one step further and actually try it out.

The actual article is only three pages long and is very easy to read, so if you want more details I’ll direct you straight to the source. But the main suggestion of the article is that using a very simple formula and making two measurements, you can get a rough estimate of the velocity of a boat. The formula is simply,

boat velocity =  1.25 * Sqrt(wl)/Sin(ang)

; wl is wavelength of wake in meters,

ang is angle between wake and boat direction of motion

The 1.25 comes from some dimensionful constants in front involving Pi and g, but if you use standard units (meters) for the wavelength of the wake, those factors just become 1.25. (The fine print also says this assumes the boat is in deep water. In shallow water this equation isn’t accurate.) You can check out the article for the real formula. To make the measurements you just need to measure an angle and the wavelength shown in the picture up at the top. You can use a protractor for the angle and a ruler for the wavelength and then use the scale given in google maps to convert between your “image length” and the actual length.

I found a boat in my area (toronto) on google maps here. Then I used gimp to measure the wavelength and angle of the wake. I then converted my image length to a real length by measuring the image length of the google scale and a simple ratio:

real distance = wavelength * real length of gscale/img length of gscale

= 76px *  10m / 93px

= 8.17m

And  I measured an angle of around 35 degrees. Plugging that into the equation I get:

boat velocity =  6.23 m/s = 22.4 km/h

I’d say that’s a fair velocity for a boat… but what do I know about boats. Try it for yourself and see if you get the same answer!

Okay. So, I have another riddle for you. This one is not really physics based, but still it can be solved with logic alone (no math). I’ll give it to you in storybook form just for fun.

Once upon a time there was a forest, and in this forest there lived a sufficiently large number of gnomes (the exact number of gnomes doesn’t matter). They were extremely logical beings and valued the needs of the group far above their own individual needs, so much so that no mirrors existed in their village, so as to keep the focus of their attention away from themselves. They valued homogeneity, which was just as well since all of them were identical… well, except for one thing: their hats. For some inexplicable reason, while most of the gnomes had red hats, there were a certain number of them (say “N”) who had blue hats. These blue hatted gnomes didn’t themselves know that they had blue hats (for lack of mirrors, you see) and it was a taboo subject of the highest degree. No gnome would EVER give any indication — verbal or otherwise — as to the color of another gnome’s hat.

One day, at one of the gnome village meetings, where all the gnomes gathered to discuss serious matters, they decided as a group that because they valued homogeneity so much, it would be better for the village if all of the blue hatted gnomes left and lived elsewhere. Nothing more was discussed. No gnomes were singled out as having blue hats. The blue hatted gnomes were simply expected to leave as soon as they knew they had blue hats.

How many village meetings passed before all of the blue hatted gnomes left?

This is a really tricky riddle. Just remember, the solution has nothing to do with the gnomes using sign language to tell other gnomes about their hats, or using spoons as mirrors to see themselves. It’s a much more elegant and logical solution. If you haven’t heard it before, feel free to bounce ideas back and forth in the comments.

(Here are Part 1, Part 2 and Part 3 in case you missed them).

Well… I don’t think my students have this much conceptual difficulty, but I thought I’d start this post off with a bit of comedic relief.

Anyways, a week has passed since the last practical but I’m not behind in posting because this is the undergraduate reading week. My mind has been bubbling with ideas since then; most of which are the result of a TA brainstorming session we had on Friday. A group of enthusiastic learning assistants (lured partly by free pizza) gathered to share their ideas, concerns and advice with a representative from the undergraduate education department (or something of that sort). It looks like there are a lot of problems with this new physics curriculum (IE: the “practical sessions”). We conveyed a lot of worries and put forth a lot of suggestions which I will try to summarize here.

What I should first mention is that I am not alone in my difficulties. Almost all of the other learning assistants are, like me, having difficulties. Here are, in my opinion, the top three problems that we and the students are having with this course:

1. The TAs and the students have a severe lack of feedback from each other.
2. Students won’t ask questions about anything they’ve been having trouble understanding in class, on an assignment, or anything outside the lab activity.
3. The students have difficulty finishing the activities before the end of the practical. This leaves almost no time for theoretical (tutorial-like) questions.

So. Problem 1 (The biggest):

Students need feedback on their work so that they can narrow down what it is they don’t understand. I think one of the hardest things about learning (in a student’s reference frame) is figuring out what it is you don’t know. But students are not given any feedback on their lab book (aside from an initial trial grading of the first activity). The reason for this is that not all activities in their lab books will get graded, and the choice of which ones will be graded is kept secret until midterm. The problem is that the TAs haven’t been told either… so we can’t go through on a weekly basis and put comments in the lab books because we haven’t been assigned enough hours to do that much “correcting”. Hopefully this will be easily taken care of by simply telling the TAs to grade a subset of the week’s activities on a regular basis.

Students need meaningful feedback when feedback is given to them. It’s quite deceiving when a computer tells a student that they’ve gotten the question 100% right when the truth of the matter is there are many things they still don’t understand. But this is what is happening. Each week the students are expected to complete an online assignment hosted by the Mastering Physics website. The problem with these assignments, I think, is best conveyed using the analogy of — and I apologize to the students for this analogy — trying to teach a donkey the way into town by leading it with a carrot on a stick, then expecting it to be able to make the journey on its own. The questions on the Mastering Physics assignments are good questions BUT they are asked in such a way that holds the students hands and practically gives them the answers to each step. This severely reduces the effectiveness of the questions. When I asked one of the students if she had trouble with the Mastering Physics questions she replied, “Well, I got the question right … but I still don’t understand what I did“. Other TAs and even past students have told me similar stories about these assignments.

… but perhaps these assignments are intended to be more useful as feedback for the TAs, you say?

If this were the case, then at least their existence would have some merit. The fact that the vast majority of the students in my section get above 90% on every question should illustrate that this is not very helpful as feedback for us. Apparently this Mastering Physics site has been used for years, much before the recent curriculum change. I think it was part of an effort to recycle old bits of curriculum that is falling short.

It also looks like a good example of an over-reliance on technology to improve education. Computers don’t teach people; people teach people. Fancy gadgets, clickers and advanced quizzing systems are a great idea, but they themselves are not enough. They need to be used effectively. I think this curriculum is still in its early stages of metamorphosis and everyone is still trying to figure out more effective ways of using the new technology and new teaching methods.

Possible solution to all three problems:

One fantastic solution to this problem came together as a melange of a few suggestions in the TA brainstorming session. The organizers of this course got rid of the formal tutorial sessions because they deemed them ineffective and thought it would be more effective to work that kind of material into the practicals. The way we are currently doing this is not working. Instead, what would be more helpful is to have “theoretical” questions as part of the lab activities. There are several benefits to this if it is conducted well.

Firstly, it would encourage the students to work out questions as groups inside the practical sessions. They could get immediate feedback from the TA, and if they worked out the question on their fancy new whiteboards (which I found to be an effective method when I tried it last week) the TA could immediately gather feedback from them in terms of conceptual difficulties and so forth. The questions could be made more difficult without the “hand holding” formulation because if they truly got stuck, they could ask the TA who would be able to gauge what hints were just enough to get the group back on track.

Secondly, the questions could be directly related to the lab activities they would do immediately after. This could solidify their understanding and also make it more interesting. They would be able to see the physics happen on paper, and then in real life. From a purely personal perspective, I frequently found the classroom material to be detached from “real life” physics when I was an undergraduate. It would be nice for the students to see a strong connection between the two through the curriculum.

Thirdly, and most importantly, it would give the students a taste of real science. IE: using a model to derive a prediction (hypothesis) and test it out in the lab. This would also mean that students could be expected to come up with their own experiment (perhaps with the TA’s help) in order to test their prediction. This would eliminate the mundanity of following lab activity instructions step-by-step with no real thought behind it (as was very common for me in my undergraduate days).

In all, I think it’s been a productive week for me as a learning assistant. I’ve pretty much given up on addressing them as a class in an attempt to gather conceptual difficulties. Instead what I found more useful was to visit each workstation  individually. They are much less shy when I do that. That, in conjunction with having them work out a tricky problem on their whiteboards, will hopefully generate a better feedback loop between us.

I’d love to see more of these TA brainstorming sessions for other courses. I think much can be gained from a diverse group of minds and some free pizza.

Quantum mechanics is weird. It gets even weirder when you try to interpret what the theory is telling you about “reality”. In fact, I’m taking a course at the moment called: Interpretations of Quantum Mechanics. I’m hoping eventually I’ll get some blogable material out of it.

For now, I have a question for you all. It will be a purely subjective question (not like last time). I’ve blogged about the random nature of the quantum world before, and I’ve also given an account of an experiment that demonstrated the requirement (under certain assumptions) for an inherently random world, but the nature of reality is still a hotly debated topic in the world of physics. Some physicists reject the notion of a world that is fundamentally random and instead consider the possibility that we’re not seeing the whole picture. They come up with, so called, hidden variable theories that attempt to explain away the randomness by postulating some hidden property in the small world that we can’t directly measure. I’ve also recently come across a paper that hypothesises that the (random) quantum mechanical nature of the very very small could be an emergent phenomenon; that is to say (in pedestrian terms) we aren’t squinting hard enough to see all of the information about a quantum system and this lack of information results in seemingly random behaviour.

I wish I understood these things well enough to explain them here… but I don’t. Instead I’d like to know what your personal preference is for reality and why.

Which description of reality are you (secretly?) cheering for? Are you more comfortable with the completely non-random deterministic view of the world, or are you instead enjoying the idea of a world built on random behaviour? AND WHY?

(Here is Part 1 and Part 2, in case you missed them).

Sorry for the silence this week… you know how it is.

Before I begin, looks like the MIT physics department is having a few troubles of its own with the new physics curriculum. And, don’t forget to check out the First Excited State for Week 2 of the teaching journal.

I need your help. The practicals are becoming slightly tricky in terms of grabbing students’ attention for tutorial-like situation. As I mentioned last week, the students are vastly more motivated to do the activities than ask tutorial questions because they will be getting graded on the activities. We have the ability to create quiz questions on their workstation computers and we’ve tried creating a quiz question to try to draw out questions from the students. What actually happened was they spent a little while on the question, guessed if necessary (since it wasn’t worth any grades) and then didn’t ask any questions (probably for fear of not having enough time to do the lab activity).

I’ve been toying with a few ideas to try to get their participation in asking questions. The first is instead of asking the whole class a question and going over the solution, to instead go around and ask each workstation one at a time. It would take up the same amount of time for the students. The upside is that they will be much less shy and almost certainly reveal any gaps they have in their understanding. The downside is that any enlightening bit of information will be confined to that table.

In order for the whole class to benefit, I’d have to somehow engage the whole class in problem solving. One general idea I’ve had in that respect is to do away with a multiple choice quiz type question (and eliminate half hazard guesses) and instead ask an involved/conceptual problem. They could then write their answers/ideas on their whiteboards and share their ideas with the rest of the class. Alternately, if they are too shy to speak up, I could go around the class while they are working on the activities and look at the ideas on their whiteboards and discuss with them.

I think the problem here is shyness and time constraints. I’m wondering if any of you have ideas to get students to participate in sharing their conceptual difficulties with the class. Also, I’m wondering if any of you have any ideas for relatively short, interesting questions on the subject of static electricity.

(Here is Part 1, in case you missed it).

Looks like there’s also a duality in the blogosphere. Over at The First Excited State, our favorite semi-anonymous author is joining me in this teaching assistant blogothon with his weekly Teaching Journal.

Anyways, another week, another practical session. As I mentioned in Part 1, this week the students measured the speed of sound. So far, the activities seem to be on the right track. They encourage a bit of playfulness and try to help students get some physical intuition about the concepts they learn in class. This week, for example, on of the questions asked the students to play around with the microphone; whistle into it, speak into it, etc, and look at the resulting waveform on the computer screen. It’s interesting to see how the students react to this type of question. One of the students apparently sang into the microphone in an enthusiastic operatic manner and when he noticed that he was being watched by a TA, he expressed very apologetic sentiments. I think it was a small illustration of a student conditioned to believe in the myth that you can’t be learning if you’re having fun. I try to encourage such playfulness. I went around the room telling students to try getting two people to whistle into the microphone at slightly different pitches. I demonstrated this to one of the workspace groups and they were impressed that they could actually see the beats show up on the computer screen.

That being said, there are some problems creeping up. The most prevalent is time constraint. These practicals are supposed to replace the labs AND the tutorials. Each week we have two hours to try to fit in these activities and a little problem session. So far, the activities have taken the students the full two hours. Since students are being graded on the activities and students tend to take a very grade-oriented view of education, the TAs and the students both feel pressured to just ignore the problem sessions and do the activities.

Fortunately, we’ve been given the freedom to grade the students’ workbooks as we see fit. If the majority of students don’t have time to finish all of the “required” activities, then we have the authority to issue grades which compensate for this. The wonderful fact about the grading scheme is that it is on a scale of: 0-4. This means that the majority of the time, the majority of the groups will get a 3. This not only takes pressure off of the TAs that grade them but also it removes much of the competitive pressure on the students. We’re, after all, trying to remove the grade-hungry attitude some of these students have to education. I am going one step further and not showing the students their grade unless they explicitly ask me for it. I’m hoping this will force them to pay attention to the detailed feedback I give them in their workbooks, which, unlike an obscure number, is what will really help them know how they’re doing in the course.

Finally, I’d like to point you to a post on the School of Everything blog to do with something I’ve been thinking about for a little while: adapting teaching methods to reflect the diversity in ways people learn. It goes over the great uncertainty in classification of learning styles and the difficulty this causes in trying to generate a teaching style that accounts for the diversity of people’s minds. I found it very interesting, and thought you might too.

I thought it was about time I gave you (yes you!) a physics riddle to go with your morning coffee. I’ll state the problem first and then give a few hints below the fold. Readers with a familiarity with ideas in physics can probably solve this without any hints. If you are unfamiliar with physics, don’t be ashamed to check out the hints. Most importantly: this riddle can be solved without any equations. Feel free to post your solutions in the comments. I’ll give the solution as a comment later on.

Okay. Here it is:

Not to scale...

You have two objects:

• A rope of length a given length.
• Two pieces of (let’s say…) wood joined by a bolt. Together these pieces of wood stretch out to be the same length as the rope.

These objects are the same length, same mass and the same mass per unit length. You now hang them by their endpoints so that they hang side by side (as shown in the picture). The horizontal distance between the endpoints on which they hang is the same for the wood pieces as it is for the rope.

Which object has the lower center of mass?

Note: If you are unfamiliar with the concept of center of mass, check out Rhett’s post on DotPhysics here. You don’t need to understand it all for the purposes of this problem, just know what center of mass is.

Now, some hints:

1) Think about what a lower center of mass means in terms of the potential energy. If an object has a lower center of mass, then it has less potential energy.

…

…

…

2) Objects tend to like to lower their energy any way they can. If an object has a certain amount of energy and is able to shift its configuration in a way that immediately lowers its energy, then it will do so.

Good luck!

Well, the first of my first “physics practicals” were this week. By this I’m referring to the TA job I’ve been raving about. I promised pictures of the shiny new rooms we get to use, so without further ado:

Behold!

So hopefully these pictures will help you understand why I say the new rooms feel like a sportscar.

… okay, so if they feel like a sportscar, how’s the mileage, you ask?

A fair question. The way these rooms are constructed make them ideal for group interaction. They take focus off of the LA, which is as it should be. The LA is not a lecturer. But for that same reason it is very difficult for the LA to hold students’ attentions if they are telling them something important. To compensate for this they have a wireless microphone and speakers installed to give LAs voices a sort of omnipresence in the room. In addition to that the LAs have the ability to control the students’ computers (individually or in bulk) from the main computer at the front of the room; projecting information onto them, creating mini quizzes, taking full control, writing on them, etc. Overuse of these tools could result in the students going through a whole practical without interacting directly with the LA. I see this as a potentially bad thing. So what I’ve tried to do is avoid using the microphone altogether. Nothing says I need to address the class from the front of the room. I just walk to the middle where everyone can hear me better.

This is what I did the first day, and before I opened my mouth I suddenly felt that sensation I had been warned about by my TA friends: the moment of dread. All of those eyes of students in a required course, some of whom hate physics and don’t want to be there, staring at me, expecting me to do something… after about five seconds it passed and I broke the silence with an overly enthusiastic “HI!”. (I might have scared a few). After that I radiated as much enthusiasm and personality as I could muster. One of the first questions I asked them was: “who here absolutely hates physics?”. Out of a class of about thirty students, seven hands shot up. I’m focusing on those seven. If I can make them curious about physics, the rest will be a piece of cake.

The first practical’s activities were a bit of a drag. They mainly involved analyzing flash simulations of waves. Next practical, however, will be fun. I’ve got it all planned out. The scheduled activity for that practical will be measuring the speed of sound using a standing sound wave in a closed tube. The physics and process behind that experiment is completely analogous to my post about measuring the speed of light with chocolate and a microwave. They will use a microphone to find the pressure nodes (quiet bits: reverse analog of the soft bits of the chocolate), and use this to measure the wavelength for a given frequency (pitch).

My plan is to begin the practical by showing this youtube video. It’s a video of a Ruben’s Tube (if you haven’t seen a Ruben’s Tube you must watch that video). The physics behind the shape of the flame in a Ruben’s Tube is the same physics they will be using in their activity. With a Ruben’s Tube you could just take a ruler and measure the wavelength directly since you can see the shape of the wave in the fire. Unfortunately for the students, they won’t have that spectacular representation of the wave and will have to resort to using a microphone to find the quiet bits.

I’ve been keeping notes of ideas I have to make the practicals better. My plan is to get as much feedback from the students as possible. Hopefully some fine tuning will get everyone’s enthusiasm resonating throughout the practicals.

I’ve been meaning to post this for a while, but kept putting it off because I anticipated it being a rather long post. Several months ago I attended a lecture given by Lawrence Krauss at the CUPC. He gave us an overview of a “debate” he had with Freeman Dyson about whether or not life could exist forever. Keep in mind, this is not an argument for the likeliness of eternal life, it’s just simply addressing the possibility of it. In physics, the questions about whether or not something is even remotely physically possible are, many times, the most fun! And the ideas Krauss shared with us that originated from his back-and-forth with Dyson were so fun and interesting that I thought I’d take a stab at reproducing an overview of it all here. Keep in mind, I will be glazing over all of the mathematics and so if you want a more in depth look at the derivations of these results you should probably check out the original papers (here is Dyson’s; here is Krauss’s). They are enjoyable to read if you have a physics background (and maybe even if you don’t). So here it goes. Dyson vs. Krauss. But before we begin this faceoff, we need to buckle down and tend to a question that is begging to be answered:

…what do we mean by “life”?

Firstly, I must mention that we are not talking about eternal life for a single being. This debate was focused on eternal life for, say, a civilization albeit one that may evolve. Secondly, living things come in many shapes and forms, some of which we may not yet be aware of. It seems unreasonable to make the assumption that all forms of life are like those on earth; carbon based, dependent on water to survive, etc. In any case, Dyson and Krauss are both physicists and so for the purposes of their debate they were more concerned with the physics of “life” than its biology. Let me put it like this: we are not really concerned with the biological processes that lead to the thought “I think therefore I am”, we are simply concerned with the existence of the thought itself to define “life”. In other words, by “life” we really mean consciousness, or more simply, computation. Consciousness seems to have a lot to do with the firing of neurons which go about processing information much like a computer (or perhaps a quantum computer). Whether or not consciousness is really akin to some kind of computer program is a whole new debate in itself (perhaps some neuroscientist readers can comment on this). Despite this, computation must at least have a lot to do with consciousness and so surely by investigating the eternal existence of computation we won’t be doing too badly.

So, what restricts us from running a computer program for all time? Well, the first barrier is: energy. Hopefully you are familiar with the fact that the universe is expanding. Not only is it expanding, it is expanding at an accelerated rate. It turns out that this puts a constraint on the amount of energy any civilization can harvest to keep them alive (computing). With a finite amount of energy available one might give up at this point and declare that life, which requires energy to sustain itself, can’t exist for an infinite amount of time. Dyson, however, was still optimistic. He realized that living things are less concerned with physical time and are more concerned with, what he calls, subjective time. Living things measure time by the number of thoughts they have, so if a civilization can have an infinite number of thoughts using only a finite amount of energy, one could say that they have achieved eternal life. This subjective time depends on the temperature at which the entity operates. So if we assume that the civilization has the ability to change its temperature at whim, at first glance it seems like the civilization can have an infinite number of thoughts (live for an infinite subjective time) if it keeps decreasing its temperature for all time (getting closer and closer to absolute zero, but never exactly zero). That strategy (again, at first glance) will allow an infinite number of thoughts using only a finite amount of energy.

So, is this strategy really possible? Well, in answering this question we come to the next roadblock: heat dissipation. Computation generates heat (there’s a reason your computer gets warm when you turn it on). Living things will also generate heat. Even if we ignore all of the heat generated from familiar biological functions and only focus on the heat generated from thinking, we still have a minimum rate for heat production of a living entity. This heat has to be radiated away at a rate greater or equal to the rate at which the heat is produced, or the entity will “die” (there’s a reason your computer’s CPU needs a fan). Dyson considered this and deduced that the best way to get rid of waste heat would be through electromagnetic radiation. However, going through the math he deduced that the rate of radiation of waste heat this way would depend on the temperature and the number of electrons of which the entity was made. And if the life form kept reducing its temperature in this way, there would eventually be a time when it could not radiate its heat fast enough with only a finite number of electrons. So, this couldn’t work. Did Dyson give up?

Nope.

Think about this: what if you really really wanted to go about running a computation on your laptop but your fan couldn’t cool it off quickly enough. What would you do? What Dyson would probably do, is run the computation for a while, put the computer into sleep mode, let it cool off, wake it up, continue the computation and then repeat this until the computation was done! That’s exactly what he suggested a civilization might try to do to live forever; namely periodically hibernate in order to get rid of the excess waste heat! The civilization could continually lower its temperature (decrease its metabolism) and periodically hibernate for longer and longer in order to have an infinite number of thoughts using a finite amount of energy.

A nice strategy… but this is where Krauss stepped in and poked a lot of holes in this argument. The first caveat comes from the necessity for some kind of alarm clock to wake up the civilization from its hibernation. Any alarm clock is inevitably going to be performing some kind of computation in order to calculate when it should “ring” and tell the life forms to wake up and smell the coffee. This alarm clock is subject to the same laws of physics as the life forms themselves and, as such, will eventually use up all energy reserves by the same arguments as above (since a hibernating alarm clock would defeat the purpose).

The second caveat comes from the fact that we are living in a universe which is expanding at an accelerated rate. It turns out that a universe with that property will be permeated by background thermal radiation (analogous to Hawking radiation) which means a lower cutoff for temperature. In short, in a universe undergoing accelerated expansion there is a minimum temperature, which means that Dyson’s strategy of continually reducing a civilization’s temperature won’t work.

Now, you may have heard a bit about quantum computers and be thinking: “… but quantum computation doesn’t necessarily require any energy. You can, in principal, do as many computations as you like without generating heat as long as you don’t measure the result”. If you did think of that, great! However, as Krauss pointed out, you’ll necessarily have to radiate heat if you want to do any erasing in order to prepare for a new computation. If you had an infinite amount of memory storage available you could ignore that point, but any civilization’s memory storage is limited by the number of particles it has access to, which is (as with the case of energy) limited in supply. Krauss sums up this point well.

Thus any civilization can have only a finite total memory available, and resetting registers is therefore essential for any organism interacting with its environment, or initiating new calculations. While an existence, even nirvana, might be possible without this, we do not believe it is sensible to define this as life.

So right now it looks as though life (as some form of computation), by its very nature, must end. Mortality is a necessity of life. I am actually fond of this wistful result. I find it gives life more meaning and makes it more precious… but that’s just me. What do you think?

… so what? Another year, another orbit of the earth. What’s the big deal, you say?

Well! I have some New Year’s news for you. Firstly, did you know that this year we get an extra second? To deal with this I suggest counting like a computer scientist; …3, 2, 1, 0! Happy New Year!

This year will, apparently, be the International Year of Astronomy! Georgia at Earth & Sky Science has found a great way to celebrate: 365 days of Astronomy Podcasts.

If that’s not enough, why not follow your lightcone this year? I found a great site that provides an RSS feed of astronomical bodies you (yes you!) could possibly have influenced since your birth.

… what’s a lightcone, you ask?

A lightcone is the 4-D surface in space and time that a flash of light forms as it travels away from its origin. The name is actually a bit misleading. It’s less of a cone, and more of a hyper-cone; that is a cone in four dimensions. Imagine a flash of light. As it moves forward in time the light will move outwards in all directions. At any point in time the light will be confined to the area of a sphere. As time progresses, the sphere will grow in size at a constant rate. If we think of time as another dimension, and tried to draw a 4-D graph of the flash, it would be a hyper-cone.

If you are still confused, a good way to begin thinking about this is to imagine a very small circle lying flat on the ground. Now, imagine it growing and as it grows you move it upwards. Every time the circle grows one centimeter in radius, it moves one centimeter higher up. This traces out the 3-D cone you know and love. The upward direction represents time and the other directions represent a 2-D space. To generalize to a 3-D space with time, you change the idea of a growing circle to a growing sphere. Et voila: a lightcone.

… ok, so what’s so special about a lightcone, you ask?

Since a lightcone is the boundary on which a flash of light travels, and nothing can travel faster than light, the lightcone also marks the boundary of influence of a certain action. Let’s say, for example, you sneezed. Achoo. At some other time, in some other place, let’s say a book fell over. Could your sneeze have possibly caused the book to fall over? What you could do is mark two points on a graph; one representing the time and place of your sneeze and the other representing the time and place of the falling book. You could draw a lightcone originating at the sneeze point. If the other point is outside this lightcone then it is physically impossible for your sneeze to have caused the book to fall over.

You could also do the same for your birth. Draw a cone originating from earth at your birthday. Now draw points for all the stars in the sky at time: today. Any points inside your lightcone could have been influenced by your birth. The word “could” is in italics because it’s really saying: “sure, the laws of special relativity don’t disagree with you… but… there’s more to cause and effect than lightcones”. Still, it’s a fun way to learn about astronomy!

So this year be aware of your lightcone and keep track of the people and events inside it. The range of influence of your actions is probably a lot more vast than you originally thought…

Canadians know snow. Recently, I’ve been around Toronto and Montreal and I’ve been exposed to a great deal of snow. Delayed street cars; slushy, slippery sidewalks; frosty faces; hail and hazard lights on highways. These are just some of the things I’ve dealt with this past week…

But there’s a warmer side to the white stuff which one of my dearest friends reminded me of two nights ago.  She drew my attention to the fluffy, freshly fallen snowflakes which sparkled under the illumination of the streetlights. She had heard that there was some interesting physics behind the glisten of snow (of which I had no knowledge). She asked me to, one day, explain it to her. I love questions like this, so I decided to do a bit of googling.

…what makes snow sparkle, you ask?

First, let’s take a look at snowflakes in general. They can come in simple hexagonal shapes or complex tree-like crystals. So much could be said about the anatomy of snowflakes, most of which I couldn’t tell you because I don’t know (but here’s a link that might help). The key point I would like to get across is best illustrated by the graph to the left. The graph shows temperature decreasing to the right and humidity increasing upwards. While the more complex, pretty snowflakes tend to form at high humidity, the type of crystals that sparkle are actually the simple ones near the bottom of the graph. These plates and prisms at low humidity have large flat surfaces which act like mirrors reflecting almost all light that hits them. These snowflakes are randomly scattered on the ground and will reflect the dimmed light reflected from the trees, cars, and whatever else happens to be around into your eyes. The majority of the snowflakes will appear to have some average brightness, however, some snowflakes will happen to be at the correct angle to reflect light emitted directly from a light source (like the sun, or streetlights). It is these snowflakes which will be almost as bright as the light source itself; they will stand out and glisten. As you move your field of view, these snowflakes will no longer be properly oriented to reflect the light source and, instead, other snowflakes will stand out. The sparkling will appear to move as you do, in a sort of spectacular specular reflection.

But wait! There’s more!

These simple snowflakes don’t only need to reflect, they can also refract light. Refraction, in case you’ve forgotten, is the bending of light as it enters or exits a different material. The angle of refraction depends primarily on the materials it is entering and exiting, but it also depends on the frequency (color) of the light. Different colors of light will bend different amounts as they enter and exit a snow crystal. White light (coming from the sun, or a streetlight) consists of many different colors of light, these colors will be separated by the snow crystal as it passes through a prismic snow crystal. This is called dispersion. So if you are far enough away from the sparkling snow that the colors have separated significantly, you may see certain snow crystals as being certain colors! The result is something like this:

So on the next dry winter night after a fresh snowfall, take a look outside and see if you can spot some spectacular specular reflection, or even the colorful dispersion of randomly assorted snowy prisms.

Sorry for the lack of posts. I have lots to write, but no time to type it. I guarantee a bunch of neat posts over the holidays…

…why are you so busy, you ask?

Here’s my week in comic form:

...Except for me it was 270...

... by hour 18 I was feeling pretty sick...

... in my defence: it wasnt goofing off, it was medicinal...

... awake -> sleep. Its kind of like a phase transition...

]]> http://morningcoffeephysics.wordpress.com/2008/12/10/examarathon/feed/ 2 Jasper ...Except for me it was 270... ... by hour 18 I was feeling pretty sick... it wasnt goofing off, it was medicinal... ... awake -> sleep. Its kind of like a phase transition... http://morningcoffeephysics.wordpress.com/2008/12/01/a-spring-ta-offer-that-adds-a-spring-to-my-step/ http://morningcoffeephysics.wordpress.com/2008/12/01/a-spring-ta-offer-that-adds-a-spring-to-my-step/#comments Mon, 01 Dec 2008 22:10:28 +0000 Jasper http://morningcoffeephysics.wordpress.com/?p=288 ]]>

Hopefully the regular readers of this blog have deduced that I am driven to invoke enthusiasm about physics (and science in general) in anyone I come into contact with. One factor motivating me is the fact that people generally have misconceptions about science and scientists that push them away from learning wonderful things about the world. Recently, I found a link to a subsite of SEED magazine that overviews the current state of science. The site, among many other things, highlights this public perception of science.

I also happily discovered that one of my fleeting ideas involving mixing coffee and science has actually been well established for a while! Maybe you’re like me and you like the idea of discussing interesting aspects of science in a coffee shop setting. If you are, and you haven’t heard of science cafés, behold!

Science cafés are live events that involve a face-to-face conversation with a scientist about current science topics. They are open to everyone, and take place in casual settings like pubs and coffeehouses.

At a café you can… learn about the latest issues in science, chat with a scientist in plain language, meet new friends, speak your mind and, talk with your mouth full.

And to make things even better, there are even a few in Canada. One of which, based in Toronto, I hope to check out sometime in the near future. When I do, you’ll hear about it.

Let me also remind you of my dissatisfaction with conventional teaching methods (in physics), which I think can potentially do more harm than good at the introductory level. After all this buildup I can now tell you what the title of this post has been alluding to and hopefully you will understand my excitement. I just attended the first TA meeting to prepare me for the new pilot physics lab course at the University of Toronto. The physics department has caught on to what physics education researchers have been saying for a while: conventional lectures add little or nothing to a student’s conceptual understanding about basic physics concepts. One tested improvement on physics education is called Peer Instruction which takes advantage of the fact that students predominantly learn best by interacting with each other. The U of T physics department is applying this method to one of the introductory physics courses. The curriculum emphasizes a hands-on approach to learning. Students work in small groups on conceptual problems which force them to discover things for themselves. The TAs act as guides who pose leading questions rather than giving solutions away (which sounds right up my alley!).

Even the architecture of the rooms has been completely rethought (I’ll post pictures when I have a chance). They are shiny new rooms with hexagonal workstations able to seat a group of students. The workstations are each equipped with desktop computers and conveniently placed electrical sockets (for laptops, lab apparatus, etc…). The walls adjacent to the workstations are covered with panes of translucent glass which, other than looking stylish, act as “whiteboards” on which to work. One of the professors described the motivation behind the architecture as follows:

If you walk into a fast-food joint, there is an obviously placed counter underneath billboards that show the menu items and combos. There is a cash register at one end and meal trays on the other. Upon seeing this configuration, it is obvious that a customer should walk up to the counter, place their order, pay, and then sit down and eat. By contrast, a fancy restaurant contains groups of tables and a cash register near the door. Again, the architecture communicates that in order to get food, one should sit down, wait for someone to take your order, then pay when you are ready to leave.

In the same way, a lecture hall gives the following message to a student: sit down, the teacher will be the center of your attention, and don’t talk to each other. These new rooms fight that message by encouraging the opposite: group work and peer instruction.

Apparently they’ve conducted a pilot program for this course. I asked about the effect it has had on the students’ learning and overall impression of physics. The professor commented that the grades on the midterm have greatly improved from previous years. But what I find more exciting is his comment that he now sees students who, after being forced to leave the classroom, seek out unlocked classrooms to further discuss with each other what they’ve just learned! And these aren’t physics majors. These are students from varied programs of study!

… and I get to be a Teaching Assistant…
or should that be Learning Assistant now…

This is a rather non-serious post. You can blame Clifford at Asymptotia for it. His recent post pointed to a site called typealyzer that claims to measure your blog’s “type”. This type classification seems to be based on the Myers-Briggs type indication tests. I thought I’d play along just for fun. Here are the results:

INTP – The Thinkers
The logical and analytical type. They are especially attuned to difficult creative and intellectual challenges and always look for something more complex to dig into. They are great at finding subtle connections between things and imagine far-reaching implications.

They enjoy working with complex things using a lot of concepts and imaginative models of reality. Since they are not very good at seeing and understanding the needs of other people, they might come across as arrogant, impatient and insensitive to people that need some time to understand what they are talking about.

Well, I’m satisfied with that… except for maybe the part about me possibly coming across as arrogant, impatient and insensitive. Oh well. It also gave me a picture of my brain. Apparently there is an abundance of logic, mathematics, imagination and symbols.

Right now my brain is filled with mathematics. I’m doing some of my first TA work; correcting around 300 midterms for a Special Relativity class. I’ll let you know how that goes if I survive…

In the mean time, if you need something to read, I’d recommend checking out this essay by Alfie Kohn about how current grading schemes actually inhibit learning in our education system, and what can be done about it. (Link via: think twice)

A few days ago I was chugging through the huge list of subscriptions I have on google reader, and I came across this post at ZapperZ’s Physics and Physicists: “What Is Worse Than A “Lost Soul”? An Ignorant Lost Soul!”. I enjoy reading his opinion posts and generally agree with most of what he writes (and this post is not an exception to that trend). ZapperZ writes a rebuttal to an opinion column in an independent university online newspaper. The author of this column argues that the Humanities need more attention as an academic subject, however, the point is argued in a way that attempts to diminish the importance of Science education in a generally spiteful manner.

Today it seems like the emphasis put on math and science in our country has made students satisfied with learning by sitting in lecture and simply regurgitating facts on multiple-choice Scantrons in a mindless Dark Age of their own.
[...]
Sure, they can dazzle with Darwin’s theory and calculate quantum physics, but in the area of critical thinking, they seem to be lacking.
[...]
all we can really do as [humanities] students is hope for something better for ourselves as critical thinkers. We need to defend our education as worthwhile and pursue the humanities because we like to do what we like and leave the rest to do the math. In the end, the humanities capture what the rest cannot, and that is, what it means to be human in this chaotic world.

This encompasses two sentiments that I’ve already blogged about in “Creativity in Physics”, and “It’s not just about access, it’s about accessibility”; overlooking the creative aspects of science, and failing to realize that the scientific curiosity which inspires us to study this “chaotic world” has as much to do with “being human” as the curiosity that inspires one to pursue any other discipline. I’m not going to try to tell you why this author’s opinions are poorly motivated, ZapperZ does that well enough. I would, instead, like to ask you to look beyond the surface matter of these opinions and think about what is motivating this author’s spite and distaste for science. Presumably the only prominent experience he has had with science is through the education system. Presumably these opinions are formulated from his experiences of the science classes he has attended in high-school. I can’t help but feel that his article illustrates more than just spite for science; it illustrates a failure of the scientific education system.

Over at Backreaction, Bee has frequenly expressed the need for a scientific revolution in many aspects of society, and I would like to add to that by saying that one of the most important revolutions that has yet to take place is in education. (Physics education is what I know best, so that’s what I’ll talk about, however, it’s entirely likely that one can draw many parallels to other fields of education.) For a while now, as a student, I’ve been developing a growing suspicion that we suck at the basics. The more of my peers I talk to, the more I get the feeling that institutions just simply have no idea how to properly teach physics. I think this is largely due to lack of proper scientific research in education. Ironically, the very thing we are attempting to teach subsequent generations — namely proper application of the scientific method — is the very thing we are not applying to try to understand how best to carry that out!

When I think back to high-school, I remember the vast majority of my friends developed a loathing for physics class, and hence, physics itself. Why? Well, I think it really all comes down to lack of context. Learning is an active process; no teacher can force large amounts of information into a student’s mind. It is the student who ultimately decides what information is going to stick. Without motivating the student, without provoking thought and curiosity to learn the topic, little will actually be learned. From what I gather, the physics curriculum in high-schools seems to exhibit a very industrial approach to learning. It’s as if we are trying to program students minds like a computer. Surely you know as well as I know that students’ minds are not computers, but the curriculum doesn’t seem to reflect this truth. The students are first taught the mathematical background needed to understand physics, then they are presented with physical laws, usually in the form of easily memorizable equations, then they do some example questions which tend to be extraordinarily detached from “real life”. By this time, most students become frustrated and/or apathetic and wonder: “why the hell am I learning this?”. If the students are lucky (like I was) they will have a physics teacher who provides “interesting problems” perhaps relating to “real life” situations that provoke curiosity and creativity.

… if your teacher was so good, why did your friends get so frustrated with physics, you ask?

A valid question. Fortunately (or unfortunately) for me, I was not an “A” student. I had average grades good enough to get by, so I felt safe enough to be able to skip some of the regular homework problems in favor of the more “interesting”, ungraded problems that fell outside the regular curriculum¹. I also, luckily enough, happened to pick up a popular physics book which gave me added context and made me curious about things like relativity, curving spacetime and black holes. I reassured myself that all of these things I was learning like “vectors”, “forces” and “energy” would get me closer to understanding black holes. But as for the other students, who had no intention of becoming physicists², they were given no motivation (even from a curiosity perspective) for learning these concepts. To minimize the pain of enduring this kind of systematic force-feeding of knowledge, students begin to make their own associations; they associate specific problems with specific equations and mindlessly chug through to get a number at the end (hopefully not forgetting the units in the process).

This kind of curriculum does not facilitate the learning of creative and critical thinking that are characteristic of “real life” science³. It is, therefore, no surprise to me that many people do not associate these things with science. People, of no fault of their own, fail to realize that science is not a collection of facts, science does study the new and unexplained, and science is not a belief system; it is more like a “doubt system”.

Fortunately, people are starting to realize that the education system is not all it’s cracked up to be. I saw the first glimmer of hope (and got the courage to develop the opinions I’m presenting) after attending a lecture given at McGill by Eric Mazur of Harvard University, who is probably best known for his research in education. His findings are probably best summed up in this New York Times article. Here’s an excerpt:

From what I’ve seen, students in science classrooms throughout the country depend on the rote memorization of facts. I want to change this. The students who score high do so because they’ve learned how to regurgitate information on tests. On the whole, they haven’t understood the basic concepts behind the facts, which means they can’t apply them in the laboratory. Or in life.

Just today I read a post on sciencegeekgirl (a recent blog find for me… I’m enjoying the read) describing a lecture given by a fellow named Dan Schwartz (she has another post about his work here). Apparently he is also an education researcher and his findings point in favor of allowing students to play around with ideas and problems first, and then teaching them the material required to better understand the solutions.

[...] We train people to become expert at routine tasks, but what we need to emphasize instead is innovative experiences. Let go of what you’re told, and try something new. For one, when students innovate a solution first, then they have a context for what they’re learning. When given the solution first, they don’t have a context for it. [...]

A sense of play seems to have a strong link to creativity and learning. Running with that theme is ZapperZ who has been writing wonderful posts about how to revamp introductory physics laboratory courses (Here’s his most recent installment). He explains why intro physics labs are important for developing conceptual skills (like critical thinking) that can be carried well beyond a physics setting, why he thinks the current lab experiments are inadequate, and he also comes up with interesting ideas for experiments that engage student curiosity and creativity, like this one from his third installment:

Construct a pendulum clock. To make this clock useful, it would be helpful if the pendulum can swing back and forth once as close to 1 second as possible. Then each complete oscillation will take just one second. That way, this clock [can] measure time in increments of one second. You may use a stop watch to calibrate your pendulum to verify that it makes a one-second swing. Try to build this as accurately as possible. You must describe in detail in your lab report how you accomplish this task and why you chose to do it this way.

In addition to all of these points I’d like to mention that despite the fact that current physics curricula seem to be set up to mostly benefit future physicists and engineers⁴, most students forced to take high-school physics won’t even go on to pursue careers in science and technology. Most will, however, go on to become active citizens in a democratic society. With problems like global warming growing in urgency, and as technology becomes more and more integrated into society, widespread scientific literacy will (and has already) become overwhelmingly important for well informed political and social decisions! (And yet, studies in the U.S. show that only 55% of people tested know that the Earth requires one year to complete an orbit around the Sun. Good grief!)

…but that’s just the way I see it. What do you think? I’d love to hear your experiences with the education system regardless of your specialization (or the age of this post)!

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1. Unfortunately, as I discovered after graduating from high-school, and after the high-school obtained a new principal, my teacher had been restricted to teaching math on the grounds that he wasn’t sticking to the approved physics curriculum!
2. Actually I had no idea what “physicists” did and why they were different from engineers until the first year of my B.Sc. began. I just knew I wanted to understand the strange things about the world I heard about in books…
3. I actually wasn’t formally introduced to the scientific method until I happened to take a complementary course in psychology… and that’s where I learned it!
4. I actually don’t think the current education system, even above high-school level actually benefits future scientists and engineers much. I think creative, knowledgeable and competent researchers are produced at most educational institutions in spite of, rather than because of the education system.