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Cosmology Goes Digital

Can we really understand the cosmos, in all of its enormity and complexity? Or is cosmology just another example of humankind's hubris? There's no reason, in principle, why we shouldn't be able to uncover the secrets of the universe--its age, how its structures formed, even its fate. After all, "cosmos" is the Greek word for order, and although the first 10^-43 second following the Big Bang is scientifically out of our reach, everything that happened after that instant followed the known laws of physics. The universe may be extraordinarily complex, but it is comprehensible.

Cosmologists' understanding of the universe is only as good as their observational data. Recent observations from powerful earth-based and space-borne telescopes, including the Hubble Space Telescope have yielded a wealth of data. These observations provide the means by which to evaluate competing cosmological models. All of the current theories are variants of the Big Bang Theory which differ only in the assumed global geometry of the universe (i.e., open, closed, or flat), the amount and composition of the dark matter, and the spectrum of density fluctuations which give rise to structures.

Cosmologists are combining theory with data to build computer models which simulate the emergence and evolution of large scale structures from the minute density fluctuations in the nascent universe, and the formation of individual galaxies within the superstructures. The benchmark is, of course, all around us: how well do the models resemble the real universe?

Testing the models

Testing the validity of cosmological models is no trivial matter. Because gravity is a long-range force, large-scale structures influence the behavior of smaller structures contained within. Any model of galaxy formation, for example, must include both the galaxy itself and the galaxy cluster and supercluster to which it belongs. The model must incorporate complex physics involving many processes, again occurring over a very wide range of scales.

The cosmologists must also decide on the initial conditions that define a particular model. What is the density of matter? How great were the density fluctuations? What is the nature of the dark matter that seems to hold everything together?

Although the mathematical equations used to describe the model are relatively simple, their solutions are extraordinarily complex. They cannot be solved by purely analytic means; numerical approaches are required.

Michael Norman, NCSA/Univ. of Illinois, on-camera
Movie/Sound Byte
QuickTime Movie (2.1 MB); Sound File (1.1 MB); Text

What Does It Take...

...to Put the Universe in a Box?

The sheer complexity and scope of the calculations necessary to run such simulations dictate the use of powerful computers and advanced computer codes. Even making sense of the resulting data is a challenge, an inducement for many scientists to explore virtual reality and other novel means of visualization. Progress in computing the cosmos increasingly depends on harnessing the most advanced computing resources of many centers around the country as well as the best minds in the field.

Enter the Grand Challenge Cosmology Consortium. Comprised of cosmologists, astrophysicists and computer scientists from across the nation, this NSF-funded Grand Challenge project aims to develop and test alternative models of how the cosmos evolved its present hierarchical structure, using the latest tools and techniques in high performance computing and communications or HPCC. The scientists will be developing advanced software applications that, in turn, will push the state of the art in computing technologies.

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Copyright, (c) 1995: Board of Trustees, University of Illinois

NCSA. Last modified 10/5/95.