Move over, Ma­trix-as­tro­no­mers have done you one bet­ter, cre­at­ing what they call the first real­is­tic “vir­tual uni­verse” us­ing a com­put­er sim­ula­t­ion.

Be­fore, “no sin­gle sim­ula­t­ion was able to re­pro­duce the uni­verse on both large and small scales” at once, said astro­nom­er Mark Vo­gels­berg­er, a col­la­bo­ra­tor in the work. Called Il­lus­tris, it mim­ics a pe­ri­od of 13 bil­lion years, al­most the whole es­ti­mat­ed age of the uni­verse.

Pre­vi­ous sim­ula­t­ions were ham­pered by lack of com­put­ing pow­er and the com­p­lex­i­ties of phys­ics, sci­en­tists said. As a re­sult they were lim­it­ed in de­tail, or in the space co­vered. They had trou­ble mi­mick­ing in­ter­ac­tions-thought to strongly af­fect how the uni­verse de­vel­oped-be­tween star form­a­t­ion, stel­lar ex­plo­sions, and gi­ant black holes.

Il­lus­tris ass­umes the pres­ence of “dark mat­ter,” ma­te­ri­al be­lieved by most as­tron­omers to be an un­seen in­gre­di­ent of the uni­verse though it is de­tected only through its gra­vity.



The sim­ula­t­ion cu­be con­tains 12 bil­lion pix­els, or res­o­lu­tion points. The team ded­i­cat­ed five years to de­vel­op­ing the pro­gram. A sim­ula­t­ion run-through took three months, us­ing 8,000 com­put­er pro­ces­sors run­ning to­geth­er-an av­er­age desk­top com­put­er would have tak­en over 2,000 years to do it.

The dig­it­al re-enactment “be­gins” when the uni­verse was about a thou­sandth of its cur­rent es­ti­mat­ed age.

When as­tro­no­mers ran it, by the time it reached “p­re­sen­t,” they counted more than 41,000 ga­lax­ies in the cu­be. There was a real­is­tic mix of gal­axy types, in­clud­ing spir­al ga­lax­ies like our Milky Way, they said. It al­so recre­ated large-scale struc­tures like gal­axy clus­ters and so-called “bub­bles” and “voids” of a cos­mic “we­b,” and, on a smaller scale, the chem­is­t­ries of in­di­vid­ual ga­lax­ies.

Since light trav­els at a fixed speed, the far­ther away as­tro­no­mers look, the far­ther back in time they can see. A gal­axy one bil­lion light-years away is seen as it was a bil­lion years ago. Tele­scopes can give us views of the early uni­verse by look­ing fur­ther out, but can't show stages in one gal­ax­y's ev­o­lu­tion.

With Il­lus­tris, “we can go for­ward and back­ward in time. We can pause… and zoom in­to a sin­gle gal­axy or gal­axy clus­ter to see what's really go­ing on,” said study co-au­thor Shy Genel of the Cen­ter for As­t­ro­phys­ics. It's “like a time ma­chine.”

The team is re­leas­ing a high-definition vid­e­o, which morphs be­tween dif­fer­ent com­po­nents of the sim­ula­t­ion to high­light var­i­ous lay­ers. They're al­so re­leas­ing sev­er­al smaller vid­e­os and im­ages at www.illustris-project.org. The re­sults are re­ported in the May 8 is­sue of the jour­nal Na­ture, with Vo­gels­berger, of the Ma­ssa­chu­setts Insti­tute of Tech­no­logy/Har­vard-Smith­son­ian Cen­ter for As­t­ro­phys­ics, as lead au­thor.



Source : http://www.world-science.net