Re: [Phys-L] Sun going around the Earth?

[John Denker <jsd@av8n.com>]

On 03/26/2015 04:24 AM, Bennett wrote:
> If the Sun goes around the Earth, then so does the whole bunch of
> stars.

That's true.  Sit outside for a while some evening. 
You can watch it happen.

> That explains the expansion of the universe by centrifugal force.

I suspect that was an attempt at sarcasm, but it 
falls flat because it uses wrong physics.  If/when 
you're using a rotating reference frame, you have 
to do it right.  *If* the stars were stationary in 
the rotating reference frame *then* they would be 
subject to an unbalanced centrifugal field, but 
they aren't.  Instead, in reality, they are subject 
to a Coriolis force that balances the centrifugal 
force.

In the real world, EVERYBODY uses rotating reference 
frames some of the time.  It doesn't matter whether 
your high-school physics book says it can't be done.

If some teachers want to say "rotating frames are 
beyond the scope of the course" I'm fine with that. 
But if they say ≪rotating frames do not exist≫ 
that's just embarrassing.  It makes people think 
that physics teachers don't have good sense.

EVERYBODY uses rotating reference frames some of
the time.  This has the force of law.  For one
thing, the law requires you to stop at a stop sign.
Relativity requires us to ask, stopped in what 
reference frame?  Answer: the reference frame 
comoving and corotating with the earth.  How would
you like to get a ticket for speeding in a school 
zone, for doing 700 mph relative to the ECNR (earth 
centered nonrotating) reference frame?  Or, since 
the Subject line mentions the sun, how would you 
like to get a ticket for doing 67,000 mph relative 
to the solar system barycenter?

Along the same lines, if you are in an airplane doing
a high-G turn, it is entirely appropriate to use
a coordinate system comoving and corotating with
the plane.  Asking the pilot to do otherwise would
be perverse.  Even closer to home, you can feel
some rather significant G-forces on a playground
swing set, if you swing with a large amplitude.

Philosophers can philosophize all they want, but
they don't get to decide this issue.  In the real 
world EVERYBODY uses rotating reference frames
some of the time.  It may be convenient for some
purposes and inconvenient for others, but it's
not an issue of principle.
  https://www.av8n.com/physics/rotating-frame.htm