849: Complex Conjugate

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Complex Conjugate
Fun fact: if you say this every time a professor does something to a complex-number equation that drops the imaginary part, they'll eventually move the class to another room and tell everyone else except you.
Title text: Fun fact: if you say this every time a professor does something to a complex-number equation that drops the imaginary part, they'll eventually move the class to another room and tell everyone else except you.

Explanation

This comic is a joke on the common phrase "Shit just got real", meaning that something has suddenly increased in difficulty so it is now a real challenge. Cueball is standing in front of a board delivering a lesson, and is about to multiply a wavefunction by its complex conjugate. In mathematics, the product of a complex number and its conjugate removes the imaginary part, effectively making it "real". Accordingly, Cueball dictates that the people who are not skilled enough to leave. The title text states that if you joke about this every time it's applicable, the class will ditch you and attempt to take place in another room.

Transcript

[Cueball is standing at a whiteboard covered in equations, one of which is the time dependent Schrodinger equation.]
Cueball: Okay, anyone who's feeling like they can't handle the physics here should probably just leave now.
Cueball: Because I'm multiplying the wavefunction by its complex conjugate.
Cueball: That's right.
[Dramatic zoom. It appears the teacher is writing on the side of the panel.]
Cueball: Shit just got real.
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Discussion

Actually multiplying complex number (x + iy) by its complex conjugate (x - iy) does not "remove" imaginary part, but calculate square of absolute value of complex number, (x^2 + y^2). BTW. in quantum physics the wavefunction is complex valued, and its absolute value is probability density (a real valued function). --JakubNarebski (talk) 00:57, 18 December 2012 (UTC)

I got hit in the face with my complex conjugate and lost an eye. 108.162.238.114 (talk) (please sign your comments with ~~~~)
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