I would like to know how is the pressure on an object (black on figure). The pressure is not a classical pressure like gas but is given by macroscopic balls. Balls are like magnets, North pole outside and South pole inside with iron for give roads to magnetic fields (see figure). All balls repuls themselves with a force like f(1/d²). All balls are free to move. I put black object and balls in a recipient and reduce volume for have pressure. But after all volumes are constants. Black object is fixed. Imagine balls like a homogenous North pole outside, it's more complex than I drawn, sure. I drawn big balls but imagine smaller in reality. Balls on figure are not exactly like that in reality, pressure is higher at external, the pressure inside "circle" is not homogous. Fixed black object don't have magnetic field, imagine it like wood for example. My question is : is the pressure in each point the same on the black fixed object ? (point where there is a contact).