Ok, let’s start with something simple to warm you up: A duck’s wake.
And wind waves (coming in from the top right) hitting a patch of moss on the side of this little pier, and then radiating away as half circles.
Here is a movie of that because it’t pretty cool, actually.
Are you ready for the cool stuff? A water strider making waves in the movie below! It hops happily on the water, and every time it lands, capillary waves radiate outward from its point of impact.
And in the movie below, there is another water popping up after a couple of seconds. But what I find fascinating about the movie below: In the beginning, there are these smooth waves running through that were created by a breeze further upwind on the lake. But over the course of the movie, the texture of the surface changes: It gets rougher and ripples appear as the breeze moves in where I am filming. So within half a minute the lake looks substantially different!
And below a movie clip that should be used in physics classes because it illustrates so nicely that waves transport energy, not matter. How do we see that?
Can you spot the long waves going through right to left, and the small ripples that seem to, if anything, move from left to right? (Not true, that’s an optical illusion! They are moving right to left, too, only so much slower than the longer ones)
But if water was moving with the longer waves, the small waves would have to be transported with it, just riding on the other wave field. Clearly that is not the case! And that’s because only energy and the shape of the waves is transported, not the actual water the waves consist of.
And below is the picture that I would use to open my hypothetical wave photography exhibition with. Or maybe have it printed in a size to fill a whole wall if I ever had to furnish a large house.
Using wave energy to generate electricity sounds very attractive, after all there are tons of waves and all they do (in addition to looking pretty) is eroding coast lines. But that’s exactly the problem: There is a lot of energy in waves, so wave power plants have to be extremely tough.
Below you see the waves entering a funnel that will lead them slightly uphill…
…so the water can fill up reservoir which is located higher than sea level…
…in order to drive turbines when the reservoir is emptied out again into the sea.
You already see the huge amount of energy stored in those waves, and looking at how little is left of the power plant, it’s definitely safer to stay well clear of those waves!
Check out in the movie below what it looks like when waves enter this power plant (and pay attention to the two people on the rock on the other side — they clearly didn’t expect that much energy in the waves! :-D)
After posting about how longer fetch leads to higher waves yesterday, here is why I was in that exact spot in the first place: To visit an old wave power plant on Toftøyna! The power plant was built in the 80s but destroyed only a couple of years after it had been built, so all there is to see now are some pretty exciting ruins!
Below, you see a cylinder that is a couple of meters high and some meters across, and that connects the air above the water with the water below. There used to be a turbine sitting at the top of that cylinder that used to be driven by the air column moved by waves at the base of the cylinder. The turbine is long gone, but what still happens is waves putting the water inside the cylinder into motion. And that looks pretty impressive as you see in the movie below!
Looking at those fountains shooting out of the cylinder, it’s not difficult to imagine what enormous kinds of forces the turbine had to endure before it got destroyed. Super impressive!
But what’s similarly impressive to me is how there are tiny flowers growing in this harsh environment. I guess it’s true: “life, eh, finds a way” :D
“Ready? Set! Aaaaand go!” was the command given at the start of a thumb wrestling war. In every pair of workshop participants, thumbs were being twisted, squeezed, freed again. We were given only 30 seconds to win! And then the time was over. “Who got how many points? Anybody more than 10?”. Nope. Most people only had about three. Which, turns out, was because none of us had listened to the instructions given in the beginning: We had been told to play thumb wrestling, but with the instruction to make as many points as possible. NOT to win against the person we were playing with. So the best strategy would have been to just very quickly tap on the other person’s thumb, maybe taking turns, but definitely not to twist, wriggle, squeeze and waste time fighting! Ooooops.
This is how our very busy — but also very exciting — phase at the energie:labor continued. Yesterday, we hosted Klaus Masch, creator of the simulation game “Offshore” (all of the materials for this game are online here), who gave a workshop on the theory behind simulation games and how to implement them in teaching. And since we learn best by doing and then reflecting about it (the equation for this, we learned, is DExR=L, which I remember without looking at my notes, which are on my desk at work while I am home on my sofa. DE being Direct Experience, R reflection, and L learning. And since learning is the product of DE and R, both have to be bigger than zero for learning to occur… (Or, technically, unequal to zero and of the same sign, but maybe the both-negative case doesn’t apply here ;-)) See, it left quite an impression!), we got to play the simulation game ourselves.
Now. Everybody who knows me in person knows I HATE playing any kind of games. Hate it with a passion. But since I had read so much about the benefits of simulation games in teaching, I really wanted to try it in order to get a better idea on whether I should get over myself and offer one as part of energie:labor. And I have to say, I am a convert.
In Offshore, students discuss the possible investment of their city into an offshore wind park as reaction to the political decision to quit nuclear power all throughout Germany. They research and adopt the roles of different stakeholders (the mayor, the city council, an investment banking firm, the people building the wind park, scientists, environmental groups) and debate risks and benefits. For us, that meant starting research before lunch, already in our roles, staying in the roles over our lunch breaks (which included lots of negotiations and bilateral conversations already!), doing some more research after, and then, finally, debating in the official debate. I got to play a double role: A student at the Institute of Applied Marine Science who is also active in the environmental group Save the Ocean. In a way, that role was probably the easiest of all: I had clear instructions that I was definitely against the project, so I could just be against everything but didn’t have to offer alternatives. All other roles had more balanced roles: Of course the investment people wanted to make as much money as possible from the project, but the role of my boss, for example, a professor in Applied Marine Sciences, was instructed to consider marine protection, but there was still room to interpret that in different ways.
Since Offshore is a frame game, it is quite easily adapted to different situations. One of our participants, for example, could only join after lunch. So a new role, the journalist, was invented for him and he was included in our simulation right away.
Participants in the workshop were all related to the energie:labor or KiFo in some way: Either having previously worked there, or currently working there with student projects or Master theses, or a visiting friend from the University of Applied Sciences who is involved in running their own energy lab that we cooperate with. That was great for me: Now future discussions on whether and how to use a simulation game for the energie:labor can refer to this common experience of playing together for a day, and getting so many useful tips and tricks along the way!
There were also so many useful micro teaching things going on that we can pick and choose from in other contexts, too. Below, for example, you see three participants holding hands: The one drawing on the flip chart has his eyes closed, while both others have their eyes open. And the left person has to guide the pen — through the other two! This, of course, causes a time lag between a signal going out and resulting in something on the paper, which sometimes makes it difficult to navigate the pen. Which is a great simulation of any complex system with a time lagged response: Any action you take doesn’t have visible effects right away, so it’s easy to over-correct and cause a mess just by being to fast in responding on the changes you (don’t) see that were caused by previous actions.
To get back to the thumb-wrestling in the beginning: That micro simulation game is one I, or any of the other participants, for that matter, will never forget. It was a very bold and impressive reminder that collaboration should be the first impulse rather than assuming that every situation, every game is about playing against someone. Maybe that’s what won me over to playing?
This was a really useful workshop, and I highly recommend both the instructor and the game! Thank you all for participating and thanks to our wonderful instructor! :-)
Yesterday Alice and I spent the afternoon and evening in the cute coastal town of Eckernförde, enjoying the summer-y weather, the Baltic Sea, and — of course! — the science outreach. It was European Researchers’ Night!
We represented the energie:labor and our research group by entertaining many many people in our little blue tent:
The goal was to engage the public in thinking about physics, particularly about energy. What better tool to use than a thermal imaging camera?
I’ve talked about the many ways you can play with that sort of camera before (see here), but last night was special. To catch people’s eyes and engage children as well as grown-ups, we had prepared a couple of fun experiments, for example hitting gummi bears with a hammer and observing how that changes the temperature.
Despite the large media interest we didn’t make the local newspaper’s front page today ;-)
To get an impression of how much fun we had, watch the movie below. This was an hour before the official opening of the event, and the last seconds we had to actually do things ourselves before we got run over by curious crowds. Who knew that people are so keen on learning physics? ;-)
Thanks, Alice, we are a great team and I had so much fun! :-)
Usually we see wave crests propagating, and since the eye can’t stop following them, it is easy to assume that they transport water with them instead of leaving the water put and just transporting energy. But here is an example of a situation where bubbles as tracers for water “parcels” show that, despite large waves passing, the water itself only moves up and down, and a little back and forth, but isn’t really transported away:
Of course there is some Stokes drift, but compared to the wave speed the speed associated with that is tiny…
Visualization of progressive waves: wave form and energy move forward while the rope itself stays in place.
When I talked about waves in GEOF130 recently, in order to explain the concept of progressive waves, I showed a drawing from one of the textbooks, where someone was moving a rope such that waves traveled on the rope. The idea was to show that for progressive waves the wave form and energy travel, while the matter itself stays more or less in place, only moving up and down or in circular orbital motions.
The look I got from one of the students for showing that drawing confused me a bit and I am still not sure whether it was a “I have no idea what you are trying to tell me!” or a “Duh! Are we in kindergarden?”, but I think it was probably closer to the former. So from now on I will carry a piece of rope on me to show this in lectures and to have students try themselves.
A wave shape traveling forward on a rope, while the rope itself stays in place.
I filmed a quick video because it was difficult to watch the wave while exciting it myself, but it turns out it is even more difficult to hold a camera more or less steady while exciting waves at the same time, plus the movement is pretty quick even for a camera as awesome as mine. Anyway, if you want to procrastinate learn more about waves, watch this!