These videos show why physics, the science of motion, is so captivating - be it motion in everyday life, in the universe, or under the micoscope.
How atoms switch orientation inside a magnet
This film, taken by Hendryk Richert at www.matesy.de shows how the magnetic regions in a material change when a magnet approaches. The film was simply made using a handheld magnet, a magnetooptic coating on a glass substrate and a usual video camera.
How geostationary satellites remain fixed even if the stars move
How stars orbit "our" black hole
Click here for a range of fascinating videos showing the motion, during ten years, of the stars around the huge black hole at the centre of our Galaxy. Without that black hole, the Milky Way and thus our Earth would not exist. The film was made with ESA telescopes.
The belt trick as proof of the spin-statistics theorem - First video: spin 1/2 particles are fermions because belts with buckles have spin 1/2
This beautiful animation is copyright and courtesy of Antonio Martos. Assume that the belt cannot be observed, but the square belt buckle can, and that it represents a particle. The animation then shows that such a particle (the square buckle) can return to the starting position after rotation by 4 pi (and not after 2 pi). Such a `belted' particle thus fulfills the defining property of a spin 1/2 particle: rotating it by 4 pi is equivalent to no rotation at all. (The belt thus represents the spinor wave function; for example, a 2 pi rotation leads to a twist; this means a change of the sign of the wave function. A 4 pi rotation has no influence on the wave function.) You can repeat the trick at home, with a paper strip. The equivalence is shown here with two belts attached to the buckle, but the trick works with any positive number of belts! Can you find a proof for this? By the way, such belted buckles - together with equivalent constructs made of ropes or tubes - are the only possible systems that show the spin 1/2 property.
The belt trick as proof of the spin-statistics theorem - Second video: spin 1/2 particles are fermions, because belts with buckles are fermions
This unique animation is copyright and courtesy of Antonio Martos. Assume that the belts cannot be observed, but the square buckles can, and that they represent particles. The animation shows that two particles (the two square buckles) that are connected to infinity by belts return to the original situation if they are switched in position twice (but not once). Such particles thus fulfill the defining property of fermions. (For the opposite case, that of bosons, a simple exchange would already lead to the identical situation.) You can repeat the trick at home, using paper strips. The trick is shown here with two belts per particle, but the untangling works with any number of belts! Together, the two animations are the essential parts of the proof that spin 1/2 particles are fermions. This result is called the spin-statistics theorem.
Here is a reduced version of the films for download:
Flying around the Earth is worth it
The film shows the beauty of our planet. More details can be found here.
How atoms move
This film shows the motion of a number of atoms, and the way they change position. More details here.
The flickering of stars at night
The wave properties of matter
Click here to see quantum physics in action: a visualisation of the double split experiment for matter. This might be the best way to understand quantum theory.
More videos are found inside the free textbook
The pdf files of the Motion Mountain textbook also feature embedded films of moving electrons made visible in liquid helium, of the astonishing solitons in water, of the elementary particles inside atoms, about the motion of cilia that determine that our heart grows on the left side of our body, the world seen from a relativistic car, and much more. Just download the pdf files to see these videos; they all run inside Adobe Reader.
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