Since the beginning of civilization, people have asked the same question. Today, cosmologists are seeking answers not in myth alone but in science.
But travelling back fifteen-odd billion years to the Big Bang, that fireball in which the universe was born, is impossible. Instead cosmologists must rely on powerful computers to model cosmic evolution mathematically.
Accurate modelling demands incorporating as much physics as possible. Gravity, gas motion, radiation, dark matter -- an invisible form of matter thought to comprise 90% of the Universe -- and ordinary, visible matter, step-by-step, all of these features and more must be built into the computer models.
To meet this Grand Challenge, astrophysicists at the University of Illinois and several leading research centers have joined together to develop powerful software programs for sim ulating the cosmos. Such programs can only be run efficiently on computers capable of handling billions, even trillions of calculations per second.
Employing high performance computers at many sites and new tools, such as virtual reality, to visualize their simulations, the multicenter team is creating increasingly elaborate models. As a result, it is now becoming possible to compare the predictions of theory with the observed universe.
Here, one of the largest cosmological simulations ever performed depicts the emerging structure of the universe, as seen in X rays. Based largely on computer codes developed at NCSA and Princeton University, the model predicts the distribution of extremely hot, X-ray-emitting galaxy superclusters condensing from the gravitational collapse of cosmic gases. The simulations closely matched recent observations by an orbiting X-ray telescope.
In the future, yet more intensive computer simulations will trace cosmic history over the widest range of scale, from the appearance of the largest known structures, to the formation of individual galaxies. These models will enable cosmologists to probe ever more deeply into the universe's origins, evolution and ultimate fate.
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