Credits: Barry Sanders, NCSA
The first of the three sequences created for the IMAX film depicts the universe from a few moments after the Big Bang up to the beginning of large scale structure formation in the universe. The following timeline shows a schematic description of the evolution of the universe.
Credits: Barry Sanders, NCSA
The sequence opens with a blue-white marble centered in the IMAX screen. Rocky Kolb, an astrophysicist at Fermilab, is describing how the entire observable universe; all the planets, stars, and galaxies we see; was once compressed to the size of this marble in the very early universe. The evolution of the universe begins with a furious expansion as the marble quickly fills the screen and beyond. As the expansion continues, its initially rapid pace begins to abate, reflecting the slowing of the real universe due to its own gravitation self-attraction.
The universe is, at this stage, almost completely featureless with density fluctuations of less than one part in a billion. Nevertheless, slight variations in density do exist and are the seeds of the galaxies we see around us at the present. To create a visualization, only the fluctuations in the density field are shown (else the screen would appear too smooth and one would not be able to see the expansion). These fluctuations have a slowly varying color, from blue to red, as the universe cools (note that in color temperature, "blue hot" is hotter than "red hot"). Towards the end of the segment, the universe is no longer hot enough to keep protons and electrons apart and they combine to form hydrogen atoms. This transition marks the phase known as 'recombination' and is schematically depicted on the IMAX screen by a sharp increase in the transparency of the fluctuations. The sequence ends with a cross-dissolve to the hierarchical collapse and galaxy formation simulation.
For more information about the physics behind this sequence and cosmology in general, see Cosmos in a Computer, a hypermedia exhibit on computational cosmology.
Credits: Greg Bryan (Illinois)
First, we show an example of the fluctuations typical of what is called the Harrison-Zel'dovich spectrum, which is the underlying description of density fluctuations for most of this sequence. This spectrum of fluctuations assumes that the universe has no preferred length scale and may be naturally produced by quantum fluctuations during an inflationary epoch (90k).
The second image shows fluctuations for a range of different physical scales, ranging from the Harrison-Zel`dovich spectrum in the upper-left corner, to one thought more likely to describe the seeds out of which our own galaxy grew (lower-right). During the visualization sequence, the character of the fluctuations slowly changes through these stages as the universe expands. (83k)
