# [geocentrism] Re: Uranus

• To: <geocentrism@xxxxxxxxxxxxx>
• Date: Sun, 21 Dec 2008 11:36:21 +1000
```Bernie, this below  from wiki appears  a contradiction, unless it is taken in
complete context. . I'm disappointed again in Wiki. ..  the bit you selected "A
Rotation is simply a progressive radial orientation to a common point." is not
a definition of a rotation, standing alone without the other conditions. Just
one example,   it leaves out the key word "rigid body" The simple definition
outside the mathmatical section is written above in the same article, as  :

" A rotation is a movement of an object in a circular motion. A two-dimensional
object rotates around a center (or point) of rotation. A three-dimensional
object rotates around a line called an axis. If the axis of rotation is within
the body, the body is said to rotate upon itself, or spin—    END of
definition. which implies relative speed and perhaps free-movement with angular
momentum. And note this separation and differentiation by contrast: A circular
motion about an external point, e.g. the Earth about the Sun, is called an
orbit or more properly an orbital revolution.  Note that last , Its an orbital
revolution- not a rotation. (more on that later)

From Wiki again:
In physics, a rigid body is an idealization of a solid body of finite size in
which deformation is neglected. In other words, the distance between any two
given points of a rigid body remains constant in time regardless of external
forces exerted on it. Even though such an object cannot physically exist due to
relativity, objects can normally be assumed to be perfectly rigid if they are
not moving near the speed of light

I am glad you came into this because you have neatly given me opportunity to
show  the wrong direction Allen has been leading us , in trying to make
rotation equivalent to translation, whereas they are two distinctly diferent
physical motions.as I show defined above. even though  the real definition
shows that a rigid body can be "either or a combination of both".   The example
of course is a spinning top moving around on a circle. It is "spinning"
rotating  very fast, whilst at the same time slowly prescribing an orbital
revolution around the circle.

I insert the contradiction for you. in teal    Phil
----- Original Message -----
From: Bernie Brauer
To: geocentrism@xxxxxxxxxxxxx
Sent: Sunday, December 21, 2008 8:47 AM
Subject: [geocentrism] Re: Uranus

"A Rotation is simply a progressive radial orientation to a common
point."
Above quote from:  http://en.wikipedia.org/wiki/Rotation
Excerpt Below:

----------------------------------------------------------------------------------------------
Please also note the introduction to this definition, which came later
in Wiki under the heading "Mathmatics."  why is this important? Because
Mathmatic is to do with "idealisations" or imaginary visualisations , as models
of the real world, and definitely NOT the practical observations, though of
course related to them.
"Mathematics is the academic discipline, and its supporting body of
knowledge, that involves the study of such concepts as quantity, structure,
space and change. The mathematician Benjamin Peirce called it "the science that
draws necessary conclusions".[2] Other practitioners of mathematics maintain
that mathematics is the science of pattern, and that mathematicians seek out
patterns whether found in numbers, space, science, computers, imaginary
abstractions, or elsewhere.[3][4] Mathematicians explore such concepts, aiming
to formulate new conjectures and establish their truth by rigorous deduction
from appropriately chosen axioms and definitions.[5]

Through the use of abstraction and logical reasoning, mathematics
evolved "

Thus the definition you selected comes from this academic discipline
which is outside the practical considerations Paul and I are considering using
real machines. In practical terms the moon and earth system is a machine, but
as we are limited in what we can measure there, we must resort to earth bound
mechanical models.  Real machines, not imaginative.
From wiki:  "An academic discipline, or field of study, is a branch of
knowledge which is taught or researched at the college or university level.
Disciplines are defined and recognized by the academic journals in which
research is published, and the learned societies and academic departments or
faculties to which their practitioners belong.

Fields of study usually have several sub-disciplines or branches, and
the distinguishing lines between these are often both arbitrary and ambiguous.
"   In simple terms its the "jargon of the trade" and the definition in the
section you are quoting from out of context actually begins,

"Mathematically, a rotation is a rigid body movement which, unlike a
translation, keeps a point fixed. This definition applies to rotations within
both two and three dimensions (in a plane and in space, respectively.) A
rotation in three-dimensional space keeps an entire line fixed, i.e. a rotation
in three-dimensional space is a rotation around an axis. This follows from
Euler's rotation theorem.
All rigid body movements are rotations, translations, or combinations
of the two."  So far correct   The following is almost incomprehensible, badly
formed , non definitive , as it excludes the necessary "rigid body"  and allows
, now this is the important contradiction,  it allows a translation of a non
rigid body to be called a rotation, which the first part explicitly excludes.

A Rotation is simply a progressive radial orientation to a common
point. That common point lay within the axis of that motion. The axis is 90
degrees perpendicular to the plane of the motion.
If a rotation around a point or axis is followed by a second rotation
around the same point/axis, a third rotation results. The reverse (inverse) of
a rotation is also a rotation. Thus, the rotations around a point/axis form a
group. However, a rotation around a point or axis and a rotation around a
different point/axis may result in something other than a rotation, e.g. a
which Wiki allows, and though they do eventually correct incomprehensible or
bad inputs,  it has not been done as yet. Apart from confused wording it
contradicts most of what follows. Taken from the original practical definition.
ie outside mathmatics.

Quote " A rotation is a movement of an object in a circular motion. A
two-dimensional object rotates around a center (or point) of rotation. A
three-dimensional object rotates around a line called an axis. If the axis of
rotation is within the body, the body is said to rotate upon itself, or
spin—which implies relative speed and perhaps free-movement with angular
momentum. A circular motion about an external point, e.g. the Earth about the
Sun, is called an orbit or more properly an orbital revolution.

This whole concept is beautifully bound up in the definition related to
orbital revolution,

"In physics, orbital motion is either the  motion of a planet in a
planetary orbit, or a motion of an electron around the nucleus of an atom, or
any other motion of parts of a bound system. In quantum mechanics, orbital
motion contributes to the angular momentum, but there are also other
contributions such as spin.
Philip.
```