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Andrew Brown (drusepth)
11,937 followers -
I've got my fingers in a lot of pots.
I've got my fingers in a lot of pots.

11,937 followers
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Found in Reykjavik
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Found in Reykjavik, Iceland. 
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The dodecahedron, the icosahedron and E8

The regular dodecahedron and icosahedron were not first found in nature: they were discovered by Greek mathematicians, and we first read of them in a text written by Plato. Felix Klein used them to solve the quintic equation. But this was just the first step toward a more remarkable discovery: they can be used to construct the E8 lattice - which last year was proved to give the densest packing of spheres in 8 dimensions!

On Saturday I'll give a talk about this - but you can see my slides now:

http://math.ucr.edu/home/baez/icosidodecahedron/

Even if you don't follow the math, the pictures should be fun.

It took me a while to prepare this talk, because I wanted to understand things more deeply - in particular, how E8 shows up when you do a minimal resolution of a Kleinian singularity. Now that I understand it, I want to blog about it! But not right now.

In case you're in Hong Kong:

My talk will be at 10:50 am on Saturday May 20th in Lecture Theatre G at the Hong Kong University of Science and Technology. It's part of the Annual General Meeting of the Hong Kong Mathematical Society, and you can see the program here:

http://www6.cityu.edu.hk/ma/hkms/AGM_May2017.pdf

I'm having lots of fun here in Hong Kong, and I want to blog about that too. But again, not right now!

This picture, prepared by +Abdelaziz Nait Merzouk especially for my talk, shows Klein's icosahedral function - a function on the sphere that doesn't change when you do a rotation of the icosahedron. Klein used this to solve the quintic equation.

#geometry

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pls no

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I'd listen.

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Holy wowsers. 

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Just got this. The link previews are a nice addition. 

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40-minute interview yesterday with the greatest man on the planet.

Tunnels, Tesla, SpaceX, and the future.
#ElonMusk #Tesla #SpaceX #Hyperloop #TED
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