Re: ZetaTalk and Spaceguard UK (D8)

Greg Neill wrote:
> 
> "The Small Kahuna" <[email protected]> wrote in Message <[email protected]>
> 
> >
> > The first assumption is that there are no special locations so the
> > location of the (0,0,0) point is not important, so why not set it
> > equivalent to the center of the earth?  Any place is as good as any
> > other.  This means that the motion of the earth has been "nulled out" by
> > allowing the coordinate system to move.  This assumption is reasonable
> > and supported by data that shows that we cannot seem to measure absolute
> > motion.  There is no special place or preferred direction, and we can
> > only measure our velocity in reference to something else.  So we might
> > as well drag the coordinate system with us, it simplifies the math.
> 
> Except that, if you choose to place your (0,0,0) point at the
> center of the Earth you'd better take stock of what your assumption
> implies.  It implies that you've chosen a non-inertial refererence
> frame and all the baggage that goes along with it.  You can deal
> with this in the vector equations all right, but not without some
> pain.  As far as doing math in coordinate systems goes, inertial
> frames are preferable.  In a non-inertial reference frame you
> *can* determine that you are moving by acceleration effects.

I'm glad you basically agree that the "real" math is much more complex. 
Including non-intertial reference frames is part of what I was referring
to when I mentioned the relativistic effects.  Newton's theories are
first presented to kids in High School or Junior High School (or what
ever else it is called locally), and presenting everything all at once
would probably blow most people's minds.

Like you went on to point out about how finding your car in the morning
does not require angstrom accuracy, one has to differentiate between
what is useful for performing engineering calculations and what
"explains reality".  If you want to put a man on the moon, there are
enough other unknown variables and an overwhelming desire to ensure a
safety margin that taking into account second order relativistic effects
is probably pointless.  A mid course correction burn will take care of
it.  But if you want to *explain* why the moon has been where it has for
an extended period, you just cannot hand wave, not really.  A four
billion year integral is a terrible task master.  Small effects really
do matter.  Small effects have been used to explain why the moon always
shows us the same side and tidal forces (and I mean the literal tide of
the oceans) has been shown to have an effect on the rotation of the
earth.  Neither effect is obvious at first glance and a simple equation
would not predict either effect.

> No.  This is nonsense.  First of all, Nancy is claiming a repulsive
> force that rises to overwhelm gravity at close surface distances.
> This is demonstrably silly as evidenced by the fact that you and
> I can both stand on the Earth without being tied down.  It is

Well, not exactly because what has been stated is that the repulsive
force requires an approximate balance between objects.  Neither you or I
are comparable to the earth in mass, so this is not philosophically
inconsistent (although I agree that the relevant equations have been
lacking).  Since we know so little about the repulsive force, it is
impossible to say with any certainty that it should behave one way or
another, we will need further experiments and data to develop a theory.

> also empirically false as demonstrated by recent close proximity
> measurements of G.

Can you provide a pointer for this?  I'd like to read up on it.

The Small Kahuna