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    Wow, what a masterpiece of an article with numerous great visualizations! I learned a lot!

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      Be sure to check out his archives. He has a lot of articles with amazing interactive visualizations.


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        I’m glad I read your reply, I was planning on skipping the article because I assumed I basically knew how GPS worked. Not only is it beautifully presented, it builds up each step very carefully and pointed me at quite a few bits of the problem that I’d skipped in my mental model (why the orbits were chosen and how the time synchronisation works, for example). Even the bits that I did know well, I thoroughly enjoyed reading the description and playing with the animations.

        I’m going to keep this as my gold standard reference for how to do scientific communication.

        I still find it amazing that this was launched at a time where there was still sufficient uncertainty about relativity that they built the system to operate in Einstein-was-right and Einstein-was-wrong modes, just in case they accidentally disproved his theories (as I recall, the first GPS satellites were the first clocks put into orbit that were sufficiently sensitive to measure relativistic effects). The fact that I can now buy a cheap consumer device that can receive signals from four such systems and tell me my precise location anywhere in the world is a phenomenal achievement. The fact that four such systems need to exist because four large political entities don’t trust the other three is much less of an achievement for the species.

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          GPS is just so well-designed, you put it well.

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        wow. I can’t imagine how much work went into this. it’s like an interactive textbook!