Astronomy Picture of the Day

Explanation: What if you could fly through the universe and see dark matter? While the technology for taking such a flight remains under development, the technology for visualizing such a flight has taken a grand leap forward with the completion of the Bolshoi Cosmological Simulation. After 6 million CPU hours, the world's seventh fastest supercomputer output many scientific novelties including the above flight simulation. Starting from the relatively smooth dark matter distribution of the early universe discerned from the microwave background and other large sky data sets, the Bolshoi tracked the universe's evolution to the present epoch shown above, given the standard concordance cosmology. The bright spots in the above video are all knots of normally invisible dark matter, many of which contain normal galaxies. Long filaments and clusters of galaxies, all gravitationally dominated by dark matter, become evident. Statistical comparison between the Bolshoi and current real sky maps of actual galaxies show good agreement. Although the Bolshoi simulation bolsters the existence of dark matter, many questions about our universe remain, including the composition of dark matter, the nature of dark energy, and how the first generation of stars and galaxies formed.