• Most common misconceptions in popular physics

      Somewhere in an alternative Universe, based on MWI, I became a genius in physics. But in our Universe, I just read professional publications in physics, trying to keep myself up to date, meanwhile working as pizza delivery guy as DBA. Because of a slightly deeper knowledge of the subject it is almost impossible for me to watch the Discovery channel and other popular TV shows and the YouTube videos. I see nothing but oversimplifications, lies, and half-truths and can’t enjoy the shows.

      I decided to compile a list of the most popular misconceptions. And the winner is...., or course, this one:

      The Big Bang


      Usually it is pictured like this:

      image
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    • Stonehenge. The secrets of megaliths

        A version how people transported megaliths in Stonehenge.

        image

        They started their work in summer.

        They prepared road for transportation. They needed a clean and glade road without stones and other irregularities. (No.4 on picture)
        Perhaps they cut the topsoil and covered the road with clay. (No.3 on the picture)
        On each side they made curbs ( 5-10 cm). (No.2 on the picture)
        They used clay because they wanted to hold water inside the road.
        In autumn rains filled road with water. It looked like a big puddle. (No.5 on the picture)

        In winter road froze. Then they got a smooth ice skating rink slightly wider than a megalith.

        Megaliths (No.11) were transported in winter.

        Mechanism and vehicles for transportation were prepared in summer.

        Mechanism consisted of three parts.

        image
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      • How does a barcode work?

          Hi all!

          Every person is using barcodes nowadays, mostly without noticing this. When we are buying the groceries in the store, their identifiers are getting from barcodes. Its also the same with goods in the warehouses, postal parcels and so on. But not so many people actually know, how it works.

          What is 'inside' the barcode, and what is encoded on this image?



          Lets figure it out, and also lets write our own bar decoder.
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        • Researchers from MIT designed «rectenna» which converts Wi-Fi signals into electricity


            Source: eeNews Europe

            I'm glad that Habr got brand new English version. And my first post in English is about new MIT project. Researchers designed an ultra-low capacitance and ultra-low resistance Schottky diode capable of switching at GHz frequencies. This diode is able rectify and convert random WiFi signals into DC electricity.

            MoS2 «rectenna» (this is how scientists called their invention) could become the main element of roll-to-roll process to cover a huge areas. To be fair antennas capable transform radio signals in to electricity is not a new thing. The main achievement of MIT engineers is creation of soft rectenna made from special alloy.
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          • Naïve Math: the Mendocino motor and Earnshaw's theorem

            • Tutorial

            The problem statement


            I was surfing the Internet the other day and a rather curious thing caught my mind: the Mendocino motor. It’s an extremely low-friction bearing rotor: the original one had a glass cylinder hanging on two needles, but the modern ones use magnetic suspension. It’s a brushless engine: the rotor has solar batteries attached to it, which generate current for the coils wrapped around the rotor. The rotor spins in a fixed magnetic field, the solar batteries getting exposed to the light source one after the other. It’s a rather elegant solution that’s very possible to recreate at home.

            Here’s the video that explains how it works (in Russian):


            But this video had another curiosity even stronger than the engine itself. In the video description Dmitry Korzhevsky writes: “You CAN’T replace the side support with a magnet! Don’t ask me about this anymore!”
            I LOVE the 'impossible' word!