Exhibition · Series X · Instability
Gravity Amplifies a Whisper
Which density disturbances can pressure erase, and which can gravity amplify?
What to notice
The same homogeneous state contains both stable and unstable perturbations. Pressure restores short waves; self-gravity wins at long wavelengths beyond the Jeans scale.
Everyday analogy. Picture marbles on a stretched sheet. A shallow dip can draw nearby marbles inward, while the sheet’s tension resists deformation. Whether a small clump disappears or grows depends on which effect wins.
Linear Jeans-instability reference model. It demonstrates a stability boundary and does not claim to simulate nonlinear gravitational collapse.