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From: Luigi Fortunati <fortunati.luigi@gmail.com>
Newsgroups: sci.physics.research
Subject: Re: Equivalence principle
Date: Fri, 14 Jun 2024 12:42:18 PDT
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Il 13/06/2024 10:38, Hendrik van Hees ha scritto:
> The misconception is on your side, not Einstein's ;-).
> 
> An inertial frame of reference is operationally defined by Newton's Lex
> II: A body moves uniformly (or stays at rest) if it does not interact
> with anything.

Exactly, let's evaluate everything on Newton's principles and leave 
aside the curvatures of spacetime which have nothing to do with Newton.

Is the space (not spacetime) of a free-falling elevator (invented by 
Einstein and not me) enough for you as a *local* reference system? I 
hope so.

Let's see what happens in such an elevator.

In the center, there is the one meter rod placed vertically and there 
are two material points (A and B) initially next to the two ends of the 
rod.

During the fall, the rod maintains its initial length because it is rigid.

Instead, the two points A and B start moving further and further away 
from each other and also moving away from the ends of the rod.

Are the two material points stationary? No!

Do they move with uniform motion? No!

So where is the inertia of the elevator?

Luigi Fortunati