Cosmology and astrophysics
Structure formation and galaxies
Increase the growth factor D to watch small density perturbations amplified by gravity into clusters, filaments and voids of the cosmic web; compare the initial and final point distributions to recognize Jeans instability .
Equipment
- Swarm of points representing matter regions in a cosmological volume
- “Growth factor D” slider (1–10)
- “View angle” slider and 3D rotation
- “Pause” button for the structure-formation run
Procedure
Observe the nearly uniform initial state
Set “Growth factor D” to 1: the points lie nearly uniformly with slight fluctuations — modeling the early universe where the density contrast . Note the “uniformly random” look for later comparison.
Raise D and watch clusters and filaments form
Increase D gradually: slightly overdense regions pull in neighboring points — the “rich get richer” of gravitational instability — forming clusters joined by filaments, interleaved with voids. This is the simulation's version of during the linear regime.
Rotate the cosmic web and compare with surveys
Change “View angle” and drag to rotate: check that the web looks statistically the same from every direction — the universe is isotropic on large scales. Compare with real galaxy maps (2dF/SDSS surveys) and state the role of cold dark matter providing the potential wells into which gas falls.