Cosmology View

My views on Cosmology and Physics

`Book by David Michalets`

## Review of Einstein's 1920 Book on Relativity  (from Translation)

An (original) line precedes original content from the source.

A (remark) line precedes my remark from my review of the preceding original content.

My remark applies to only this section of the original.

Section IV of 35

# IV. THE GALILEIAN SYSTEM OF CO–ORDINATES

(original)

AS is well known, the fundamental law of the mechanics of Galilei-Newton, which is  known as the law of inertia, can be stated thus: A body removed sufficiently far from other bodies continues in a state of rest or of uniform motion in a straight line. This law not only says something about the motion of the bodies, but it also indicates the reference-bodies or systems of co-ordinates, permissible in mechanics, which can be used in mechanical description. The visible fixed stars are bodies for which the law of inertia certainly holds to a high degree of approximation. Now if we use a system of co-ordinates which  is rigidly attached to the earth, then,  relative to this system, every fixed star describes a circle of immense radius in the course of an astronomical day, a result which is opposed to the statement of the law of inertia. So that if we adhere to this law we must refer these motions only to systems of coordinates relative to which the fixed stars do not move in a circle. A system of co-ordinates of which the state of motion is such that the law of inertia holds relative to it is called a "Galileian system of co-ordinates." The laws of the mechanics of Galilei-Newton can be regarded as valid only for a Galileian system of co-ordinates.

(remark)

This section reveals Einstein does not understand a coordinate system and its application.

A defined coordinate system having a fixed, physical, reference point enables all other observers to repeat and verify those celestial measurements.

As described in the section Background, the celestial coordinate system uses the center of the Earth for its observer independent, physical reference point.

Here, Einstein states
(begin)
Now if we use a system of co-ordinates which  is rigidly attached to the earth, then,  relative to this system, every fixed star describes a circle of immense radius in the course of an astronomical day, a result which is opposed to the statement of the law of inertia. So that if we adhere to this law we must refer these motions only to systems of coordinates relative to which the fixed stars do not move in a circle. A system of co-ordinates of which the state of motion is such that the law of inertia holds relative to it is called a "Galileian system of co-ordinates." The laws of the mechanics of Galilei-Newton can be regarded as valid only for a Galileian system of co-ordinates.
(end)

(remark)
A star, having no visible motion in its constellation, which moves across the sky with each day to night, has its celestial coordinates measured, with Earth as the reference point.

By properly accommodating the daily rotation of the observer on Earth's surface, the measured celestial coordinates of the star will remain consistent, or that of a fixed star in the firmament.

This star is absolutely not moving in physical space, just because the Earth rotates daily.

Einstein sees a problem in fixed stars with the Newton's law of inertia.

The true problem is Einstein sees non-existent physical motion.

The measurement of a celestial coordinate is not a physical connection involved with physical, Newtonian motion.

This section is a mistake by Einstein.