Free Astronomy Magazine July-August 2014

COSMOLOGY cinema clichés and stereotypes, the au- thor's style and other factors that taken as a whole could be defined as “model”. Fortunately, nature is far less fickle and un- predictable than human beings as its basic rules are well-defined (although not de- finitive), and consequently recreating the “movie” of the universe is just a matter of computing power and precise setting of the procedure to follow. The latter is with- out doubt the longest and more complex phase. They know something regarding this about ten astrophysicists, including Mark Vogelsberger (Massachusetts Institute of Technology) and Shy Genel (Harvard-Smith- sonian Center for Astrophysics), who dedi- cated 5 years of their work to develop the procedure for accomplishing what to date is the most comprehensive and detailed simulation of the universe, Illustris. To be exact, Illustris represents the evolution of 12 billion virtual particles in a volume of (106.5 Mpc) 3 – a cube roughly 350 million light- years on each side – which is not exactly the one that moved the greatest number of ele- ments in absolute terms (think for example to the Millennium simulations based only on gravity), but even though it reproduces only a very small portion of the whole, Illu- stris has managed to recreate in an unpre- cedented detailed manner and graphic ren- dering, structures that are representative of the entire known universe. The volume occupied by Illustris is consid- ered to be the maximum that can be han- dled by current technology, consistently with the need to achieve a resolution so high to actually show the influence that the T he faithful- ness with which Illustris re- produces the mor- phological charac- teristics of gal- axies is astound- ing as can be seen by looking at the diagram below, which reproduces the Hubble se- quence in the vir- tual version. Be- sides the shapes of these galaxies, what is most strik- ing is the realism of the stellar light distribution. [Illustris Project]