Math Textbooks Are The Best

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“X-rays reveal the inner beauty of shells.” National Geographic. March 1955. 

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29.10.2015 | 16:55 Uhr |  kabel eins

Hannah Reber & Gert-Jan Akerboom

Chalcedony - Mamuju Area, Sulawesi Barat Province, Sulawesi Island, Indonesia

Quantum tunnelling

Tunneling is a quantum mechanical effect. A tunneling current occurs when electrons move through a barrier that they classically shouldn’t be able to move through. In classical terms, if you don’t have enough energy to move “over” a barrier, you won’t. However, in the quantum mechanical world, electrons have wavelike properties. These waves don’t end abruptly at a wall or barrier, but taper off quickly. If the barrier is thin enough, the probability function may extend into the next region, through the barrier! Because of the small probability of an electron being on the other side of the barrier, given enough electrons, some will indeed move through and appear on the other side. When an electron moves through the barrier in this fashion, it is called tunneling.

Quantum mechanics tells us that electrons have both wave and particle-like properties. Tunneling is an effect of the wavelike nature.

The top image shows us that when an electron (the wave) hits a barrier, the wave doesn’t abruptly end, but tapers off very quickly - exponentially. For a thick barrier, the wave doesn’t get past.

The bottom image shows the scenario if the barrier is quite thin (about a nanometer). Part of the wave does get through and therefore some electrons may appear on the other side of the barrier.

Because of the sharp decay of the probability function through the barrier, the number of electrons that will actually tunnel is very dependent upon the thickness of the barrier. The current through the barrier drops off exponentially with the barrier thickness

Source: nanoscience.com | Images: x | x | x

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Title: Grey squares rotating

Technique: Drawing with Stabilo markers on printed Blender animation (16 Frames)

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In this short film, the Macro Room team plays with the diffusion of ink in water and its interaction with various shapes. Injecting ink with a syringe results in a beautiful, billowing turbulent plume. By fiddling with the playback time, the video really highlights some of the neat instabilities the ink goes through before it mixes. Note how the yellow ink at 1:12 breaks into jellyfish-like shapes with tentacles that sprout more ink; that’s a classic form of the Rayleigh-Taylor instability, driven by the higher density ink sinking through the lower density water. Ink’s higher density is what drives the ink-falls flowing down the flowers in the final segment, too. Definitely take a couple minutes to watch the full video. (Image and video credit: Macro Room; via James H./Flow Vis)

Beautiful Geometric Skeletons of Ancient Jellyfish Fossils

The 520-million-year-old fossils reveal that ancient comb jellies had stunning geometric skeletons that have disappeared over the course of evolution, researchers report in a paper published in the journal Science Advances. These strange skeletons contained eight rigid plates that surrounded the jellies’ organs and eight spoke-like structures that radiated outward to surround the soft lobes of their bodies.

The unusual symmetry of these skeletons makes them aesthetically appealing, but it also likely provided mechanical support for the jellies’ squishy bodies. It may have aided in defense against predators or other dangers as well, the researchers suggest.

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