Quantum entanglement

There is no quantum entanglement

In physics, there is something called Malus’s law. It’s named after Étienne-Louis Malus, whose name is one of 72 names on the Eiffel Tower. It dates from way back, to 1809, and it gives the intensity of polarized light passing through an ideal polarizer: Malus’s law image from Rod Nave’s most excellent hyperphysics website This intensity is given as I = I₀ cos² θ, where I₀ is the intensity of the light that has passed through an initial polarizer, and θ is the angle between the…

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Bertlmann’s socks and the nature of reality

Last year I wrote about quantum entanglement, looking at the history and talking about the physics. I went through John Stewart Bell's famous 1964 paper On the Einstein Podolsky Rosen Paradox, and talked about Bell’s inequality, which is also known as Bell’s theorem. Now I thought I’d take a look at Bell’s 1980 paper on Bertlmann’s socks and the nature of reality. It’s freely available on a variety of websites, including the CERN document server. Bell was of course a CERN employee. It has one of…

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The double slit experiment

There’s a nice little physicsworld article dating back to 2002. It was written by then-editor Peter Rodgers, and it started by asking “What is the most beautiful experiment in physics?” The answer was, of course, the double slit experiment, which was first performed by Thomas Young in 1801: Double slit experiment image from the curiosity makes you smarter article by Ashley Hamer People refer to the double slit experiment as an example of the weirdness of quantum physics. Or to promote weird ideas such as the…

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