Large-Scale structure of the universe videos (i.e., Large-scale structure of the universe videos):
    High-cal ones:
    1. Supercomputer simulation of large scale structures in the Universe | 1:12: "Cosmological N-body simulation of the formation and evolution of the large-scale structure of the universe. The number of simulation particles is 512**3=134,217,728. The size of the simulation box is ∼ 100 Mpc (∼ 300 Mly) and uses periodic boundary conditions so that simulation particles that leave at one boundary enter at the corresponding point on the opposite boundary and periodic gravity is used in some way. This N-body simulation was carried out on the Cray XT4 at Center for Computational Astrophysics (CfCA) of National Astronomical Observatory of Japan. Simulation and Visualization: Tomoaki Ishiyama (University of Tsukuba)" (Slightly edited.)
            The simulation covers cosmological redshift z = 15.43 (i.e., cosmic time ∼ 0.26 Gyr: the z does flash onscreen if you look quick enough at t = 6 s) to z = 0 (i.e., cosmic present = to the age of the observable universe = 13.797(23) Gyr (Planck 2018)) (see "A Redshift Lookup Table for our Universe", Sergey V. Pilipenko, 2013).
            From the cosmological redshift the cosmic scale factor a(t) follows from the formula 
                 a(t) = 1/(z+1)  .
      So the cosmic scale factor a(t) so varies from 1/16.43 at z = 15.43 to 1 at cosmic present = to the age of the observable universe = 13.797(23) Gyr (Planck 2018)).
            However, the overall expansion of the universe has been divided out of the visualization since otherwise the simulation box would grow by a factor of ∼ 16.43 which would make for inadequate viewing in the video .
            By N-body simulation, we mean there are NO stars NOR any kind of baryonic matter (i.e., ordinary matter of protons, neutrons, and electrons), and all the particles in the simulation (i.e., N-bodies) represent a form of dark matter which does NOT interact, except via gravity. The particles are, in fact, point particles that NEVER collide in a body-on-body sense and they do NOT represent any actual theorized dark matter particle. The particles actually are given a mass much larger than what any theoritical dark matter particle is expected to have.
                The brightness scales with density of dark matter and is NOT an indication of emitted light. Since the particles are point particles, we see clumps of them flying through each other interacting only by gravity. Each particle, in fact, interacts gravitationally with every other particle which the overall interactions immensely complex.
            We are seeing dark matter only. The baryonic matter is dragged by the dark matter. So we are seeing the formation of the dark matter halos in which galaxies, galaxy groups, galaxy clusters, and galaxy superclusters form. We also see formation of the dark matter structure corresponding to galaxy filaments and cosmic voids. So effectively we are seeing the structure formation of the large-scale structure of the observable universe which nowadays we tend to call the cosmic web.
            Structure formation is initiated by primordial fluctuations in the primordial density of dark matter.
      It's a case of the rich getting richer and the poor getting poorer. The higher density primordial fluctuations attracted more dark matter by gravitation and grew into dark matter halos and other dark matter structures (overcoming the overall expansion of the universe) and the lower density primordial fluctuations lost dark matter and grew into cosmic voids. A fraction of baryonic matter (which is only 1/6 = 16 % of the dark matter: Ci-54) followed the dark matter into the dark matter halos and other dark matter structures and this corresponds to the formation of the primordial galaxies and other baryonic matter structures.
            Due to peculiar velocities superimposed on the overall expansion of the universe, all kinds of galaxy interactions and galaxy mergers happened during structure formation leading to hierarchical structure formation: bigger structures forming by the accretion of smaller structures: i.e., galaxies merged into bigger galaxies and these then merged into galaxy groups, galaxy clusters, and galaxy superclusters. All these events are simulated by the corresponding events in the dark matter.
            This is the best Structure formation video to show in the classroom.
    2. Large Scale Structure Formation | 1:01: This N-body simulation probably covers billions of years from cosmic time t=0.1 Gyr to several gigayears on. For more details mutatis mutandis, see the description of the first videos above. Good and short enough for the classroom.
    3. Blueprints of the Universe | 2:26: This video from ESO shows a computer simulation (probably an N-body simulation) of structure formation (i.e., the formation of the large scale structure of the observable universe or cosmic web). The cosmic time of the computer simulation is NOT specified, but it probably spans from the cosmic dark age (∼ 377 kyr (z ≅ 1100) -- ∼< 200 Myr (z ≅ 20)) to cosmic present = to the age of the observable universe = 13.797(23) Gyr (Planck 2018). For more details mutatis mutandis, see the description of the first videos above. The video is a bit long, but good for classroom.
    4. Reionization - End of the Dark Ages of the Universe | 2:05: The reionization era (cosmic time c.150 Myr --- z≅ 6, c.1 gyr for complete end) that ended the cosmic dark ages (cosmic time z≅ 11000, c.377,000 years --- z≅ 6, c.1 gyr for complete end). In the computer simulation, the expanding bright regions are the reionized regions. The reionization was caused by mainly by ultraviolet (UV) light from the early galaxies (i.e., their stars and active galaxy nuclei (AGNs), mainly quasars). Pretty to look at, but it's NOT clear what we are seeing. We seem to be flying through the growing ionized regions (the light color regions) of the reionization era (cosmic time c.150 Myr --- z≅ 6, c.1 gyr for complete end). and the expansion of the universe may not have been divided out of the visualization. Iffy for the classroom.
    5. Laniakea: Our home supercluster | 4:10: On the Laniakea Supercluster, our home galaxy supercluster by a precise definition of galaxy supercluster. However, we will NEVER have enough data yours truly thinks to use this rather elegant precise definition, except in the very local observable universe. So most galaxy superclusters will continue to be identified in the eye of the beholder. Of course, many very local galaxy superclusters will continue to have their traditional in-the-eye-of-the-beholder specifications. Is the precise definition actually good for anything? Well, the structure of galaxy superclusters that follow from the precise definition are one of the many things that structure formation computer simulations must reproduce as verification of a cosmological model. But this structure may be redundant to many other tests of cosmological models. Good and, on a leisurely day, short enough for the classroom.
    6. A Flight Through the Universe, by the Sloan Digital Sky Survey | 1:49: The flight is through an actual to-scale map of the local (i.e., contemporary) observable universe out to cosmological redshift z ≅ 0.13 and cosmological proper distance ≅ 1.3 Gly ≅ 0.4 Gpc and includes ∼ 400,000 galaxies. The galaxy images are the real images of the galaxies or, at least, of close twins of the galaxies. The flight is based on data from the Sloan Digital Sky Survey (SDSS,2000--present). Because of varying lookback time, the flight is only approximately at cosmic present t_0 = to the age of the observable universe = 13.797(23) Gyr (Planck 2018). However, the flight is with all the galaxies frozen in place with instantaneous light signalling, and so it is NOT obeying special relativity (SR). Good for the classroom.
    Low-cal ones:
    Local file: local link: large_scale_structure_videos.html.
    File: Cosmology file: large_scale_structure_videos.html.