Re: [Phys-l] Inertia frame of reference

[John Mallinckrodt <ajm@csupomona.edu>]

Even supposing that there really were such things as "fixed stars,"  
it seems to me that it would be literally impossible in practice to  
determine in a finite time whether or not one is moving at constant  
velocity with respect to them.  Am I wrong?

John Mallinckrodt
Cal Poly Pomona

On Jul 28, 2009, at 6:46 PM, chuck britton wrote:

> Absolutely no claim of being the BEST definition - but an oldie and
> goodie is one that is at rest (or moving at constant velocity) wrt
> the 'fixed' stars.
> Of course we know that there ARE no 'fixed' stars - but hey - it
> gives a starting point to argue from.
>
> Denker's 'unrestrained' free-fall frame is the modern choice of
> General Relativists.
> You might not want to say that this would be a frame that is
> 'accelerated' by the force of gravity - since general relativity sez
> that there IS no 'force of gravity'.
>
> You may not be quite ready to teach intro physics from a General
> Relativity POV. At least I HOPE you're not ;-)
>
> Use what works for you - and the smart kids will figure it out
> without suffering from too much lasting damage.
>
> On Jul 28, 2009, at Jul 28(Tue) 9:11 , carmelo@pacific.net.sg wrote:
>
> > Hi everyone,
> >
> > Does anyone know which is the best definition on inertia frame of
> > reference?
> >
> > Ohanian defines "inertial reference frame" as a frame in which
> > Newton’s
> > laws of motion are valid to a first approximation.
> > Ludwig Lange argued that any three material points simultaneously
> > projected from a single point, and moving freely in noncoplanar
> > directions, constitute an inertial system.
> > In John Denker's website, he suggests "a freely-falling frame". (It
> > seems to suggest accelerated frame of reference.)
>
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