An international group of scientists based in Germany have been focused on what happens when a laser "reads" a metal alloy disc for several years. Using one of the world's biggest supercomputers to simulate what happens nanosecond by nanosecond, their recent experiments focused on one of the most popular alloys, used to make DVDs. This alloy, AIST (which contains small amounts of silver, indium, antimony, and tellurium), gives your DVDs that pretty shine, but also have some special properties.
AIST alloys begin as what physicists call "amorphous," or "disorganized," meaning that their structure is very haphazard, but when you zap them with a laser, AIST molecules align into a perfect, crystalline lattice. The key to the process is antimony, which can switch its molecular bonds around quickly, despite having no extra space to move. AIST moves between two solid states: when you burn a DVD, you're turning its surface from an amorphous solid into a crystalline solid. Basically, your DVD is frozen into a crystalline order with the heat of a laser!
Armed with this understanding of DVDs, researchers say their work (which is also applicable to the alloys used in Blu-Rays), will help pioneer better forms of optical storage, with longer life, larger storage capacities, and shorter access times. Sounds good, but why were CDs originally 74 minutes long? That's another thing entirely...
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