What it eej?

It's an E₈, or rather, a picture of the E₈ root system.

Mathematicians have mapped the inner workings of one of the most complicated structures ever studied: the object known as the exceptional Lie group E₈.

This achievement is significant both as an advance in basic knowledge and because of the many connections between E₈ and other areas, including string theory and geometry.

The magnitude of the calculation is staggering: the answer, if written out in tiny print, would cover an area the size of Manhattan.

Mathematicians are known for their solitary work style, but the assault on E₈ is part of a large project bringing together 18 mathematicians from the U.S. and Europe for an intensive four-year collaboration.

and

The magnitude of the E₈ calculation invites comparison with the Human Genome Project. The human genome, which contains all the genetic information of a cell, is less than a gigabyte in size. The result of the E₈ calculation, which contains all the information about E₈ and its representations, is 60 gigabytes in size. That is enough space to store 45 days of continuous music in MP3 format.

While many scientific projects involve processing large amounts of data, the E₈ calculation is very different: the size of the input is comparatively small, but the answer itself is enormous, and very dense.

All we know is it looks bloody lovely. Geeky types can go here to read all about it.