**By James Dacey**

Earlier this year I wrote about a psychology experiment that revealed that mathematicians appreciate beautiful equations in the same way that people experience great works of art. In the experiment, which conjures up a slightly comical scene, mathematicians were hooked up to a functional magnetic resonance imaging (fMRI) machine and asked to view a series of equations. When the subjects looked at equations they had previously rated as beautiful, it triggered activity in a part of the emotional brain associated with the experience of visual and musical beauty. The formula most commonly rated as beautiful in the study, in both the initial survey and the brain scan, was Euler’s equation, **e ^{iπ}+ 1 = 0**.

Inspired by this study, we have put together this infographic to dissect the Euler identity and try to understand why so many mathematicians are enamoured with this little equation. Let us know what you think of the infographic and what you think are the most beautiful equations. Either post a comment below this article, or let us know on *Twitter* using the hashtag #BeautifulEquations.

The De Broglie equation:

λ = h/p,

h: the Planck constant; p, the momentum of the particle and λ, its associated wavelenght. This equation led to the “particle- wave dualty concept” and exraordinary idea of “wavefunction” and the Schrodinger’s equation.

But this is a definition rather than an equation. De Broglie’s gives sense to a particle’s wavelength, while in Euler’s all terms have been previously defined in other ways. I mean, no one says “-What is 1? +1 is -e^i*π”, what is actually true.

I like the Infographic, but you’ve reversed the captions for the basic operators. FYI.

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And this whole time I thought I had addition “+” and multiplication “x” backwards!

I prefer to think of it as saying that e^pi is the ith root of -1.

Thank you for pointing out that we had the addition “+” and multiplication “x” symbols in the wrong order. This article now contains an updated version of the infographic.

Although it is a mite complicated, I find the Lorentz Transform equations to be gorgeous considering how much they do with so little.

In fact, they are Pitagoras applied to velocity watched from another point of view.

I like 6^3 – 5^3 – 4^3 – 3^3 = 0 similar to 5^2 – 4^2 – 3^2 = 0, and the cyclic number 0.142857

What a beautiful topic! However, I am missing Einstein’s field equations of gravitational interactions, or have I overlooked it?

Great post, but you missed out the crucial importance of the “=” sign. Until we had that, we had no equations

Ah, my favourite equation. I think an equation is beautiful when it is simple and yet connected to many different ideas.

I like the Euler-Lagrange equation from variational calculus. So simple yet powerful.

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