Why G Appears Constant Locally (and When It Might Not) SERIES X — RECOMPUTING PHYSICS FROM FIRST MECHANICS What Can Be Derived from Density & Stiffness Alone? 10.6 — Why G Appears Constant Locally (and When It Might Not) If gravity is a material response of a mechanical medium, a natural objection arises: Why does

Why Time Runs Faster on Mars (Revisited Mechanically) SERIES X — RECOMPUTING PHYSICS FROM FIRST MECHANICS What Can Be Derived from Density & Stiffness Alone? In an earlier post, we noted a striking empirical fact: Clocks on Mars run faster than clocks on Earth. The difference is small—hundreds of microseconds per day—but it is real,

Why Small Bodies Are Spherical (and When They Aren’t) SERIES X — RECOMPUTING PHYSICS FROM FIRST MECHANICS What Can Be Derived from Density & Stiffness Alone? Look across the solar system and a clear pattern appears: This transition is so consistent that it even has a nickname: the “potato radius.” Why does nature draw this

Orbital Speed from Stress Balance, Not Attraction SERIES X — RECOMPUTING PHYSICS FROM FIRST MECHANICS What Can Be Derived from Density & Stiffness Alone? If gravity is not a force pulling inward, and escape is not about overcoming attraction, then a deeper question follows: What does it mean to orbit at all? In the standard

Escape Velocity Without Force Laws SERIES X — RECOMPUTING PHYSICS FROM FIRST MECHANICS What Can Be Derived from Density & Stiffness Alone? Once gravity is reinterpreted as a stored stress in a medium, a familiar quantity takes on a very different meaning: What does it mean to “escape” a planet? In the standard picture, escape

Why Surface Gravity Depends Only on Density and Radius SERIES X — RECOMPUTING PHYSICS FROM FIRST MECHANICS What Can Be Derived from Density & Stiffness Alone? One of the quiet surprises of planetary science is how simple surface gravity really is. Despite very different compositions, temperatures, and histories, the surface gravity of a rocky body