LABWORK
ANIMATING PHYSICS
animals involved. The main difference is that my professor also made a drawing on the blackboard, which helped immensely to visualize what was going on. Even better, as they could draw a piece at the time, what they had was a sort of semi-animation that changed while they were explaining the topic. Was all that drawing strictly necessary to explain Galilean invariance? Obviously not, as a paragraph of text or one line of equations can easily contain all the necessary information. On the other hand we are very visual creatures and images can help making abstract concepts more real and digestible.
Pictures that move
Figures in scientific papers are ubiquitous for a reason. Often you can get a good idea what a paper is about just by looking at the figures in it and seeing the data neatly plotted is a lot more immediate than having them tabulated. Can an animation do any better? No, but that is not what an animation is for. Since, by its own nature, an animation doesn’ t stay still for long, it is not a good fit for anything that requires looking at details. The real power of an animation is to either modify the image( e. g. zooming in on a detail) in synch with a description / explanation, or show how things change with time and / or when changing a parameter. As a practical example we can
Figure 1. A typical illustration of quantum tunnelling one might find in a textbook. The solution of the time-independent Schrödinger equation is a wave when the energy is higher than the potential, but an exponential inside the barrier, resulting in a small fraction of the wavefunction to appear beyond the barrier. look at quantum tunnelling, a topic covered in all Physics degrees that is baffling and hard to understand the first time you encounter it. The way it is approached in most textbooks is to consider a particle with a well-defined energy in a constant potential with a rectangular barrier. Then one writes the solution of the time-independent Schrödinger equation both inside and outside the barrier, and the three solutions are then joined smoothly which leads to the transmission coefficient, i. e. the probability that the particle will tunnel through the potential barrier. This is accompanied by a figure showing the potential and how the wavefunction looks like in the three regions of space of interest( see figure 1). This works very well, but leaves out all the time dynamic of quantum tunnelling, which is not hard to obtain from the single energy solution, but it is unlikely to be obvious to a student encountering it for the first time. An animation is the perfect tool to show how quantum tunnelling looks like in the time domain( see figure 2), or how it changes as the width of the barrier increases, or as the height of the barrier changes etc.
Where and when?
An obvious problem with animations is that you can’ t really show them on paper( flicking through the pages very quickly technically works but it is an impractical solution), which limits their usefulness in scientific papers. You can show animations inside a pdf [ 2 ]( you can even run Doom inside a pdf), but to the best of my knowledge there is no tool that makes that easy, and current publishing pipelines are anyway unable to deal with it. Where animations truly shine is on projected slides, e. g. in lectures or conference talks, and online, where the technology used is already perfectly suited to showing moving pictures. That said, an animation for the sake of an animation is not going to be very useful. An animation, just like a figure, should be designed to be easy to parse and to convey useful information. Worse than a figure, the more stuff is moving, the hardest it is going to understand what it is going on. An animation should always be focussed on the information it has to convey, with as few extraneous parts as possible. This doesn’ t mean one has to always go with a minimalistic style, but any extra complexity should always be there with a precise goal and any animation that is unavoidably complex should always be accompanied by a detailed explanation( see figure 3). Another thing to think about is length. How long before the animation loops and your audience will have a chance to see again the parts they missed? If you are creating a YouTube video this is not a huge concern, as it is always possible to stop it and go back if you missed something. But if you are showing the animation as part of your presentation at a conference, you have to consider that the audience is likely to be looking at the slides, looking at you, listening at you, taking notes, checking their phone and finishing their own talk, all at the same time. Chances are that they will miss those crucial 2 seconds in the animation, and then have to wait until they show again.
Different kinds of animations
" Scientific animation " is a very wide umbrella term that includes a lot of very different kinds of animations. Making a complete zoology of all possible kinds of animations is well beyond the scope of this article, but it is useful to list at least the most common ones. Data-based: You have data, but instead of plotting it as a static image you make an animation that shows how things are changing with time. E. g. one might make a video of how a slime mould grows while looking for food, or a map that shows how the borders of France changed in time. This is probably the most common kind of animation. Formula-based: Formulas have the big advantage of containing a lot of information in a very compact format, and the disadvantage of containing way too much information in a way too compact format. As a result it takes time and work to get familiar enough with the
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