1 Page 19 from the book GRAVITATION

2 Page 19 from the book GRAVITATION

3 Page 19 from the book GRAVITATION

It is IMO unfair when you compare two scientist based on the concept locality i.e. local inertial frames when one of the two does not use that concept but starts from a global coordinate system.

What is fair is when you compare a simulation (all planets around the sun) using the theories of both scientist to predict the future. In that sense each theory without any shortcut. See for example chapter 39.

Nicolaas Vroom

4 Page 19 from the book GRAVITATION

Ten years is a long time...between SR and GR.

Einstein had to learn what is this thing called...Gravity.

It took him ten years.

You don't wake up knowing this stuff, ...you got to learn it.

5 Page 19 from the book GRAVITATION

What is your point? I have nothing against SR nor GR.

The problem is you cannot compare SR with Newton's Law and then claiming that Newton's Law is wrong (More or less)

Nicolaas Vroom

6 Page 19 from the book GRAVITATION

>

In part 4 SR is mentioned. The most important issue is that Newton is not about SR but about GR. For Newton the issue is gravity. For Einstein it is both SR and GR. That means if you want to compare Einstein with Newton you should only compare, how each handles gravity related issues. As such this page gives the wrong impression.

maybe I got the wrong impression...

but who would compare einstein's SR with Newton's GR??? Certaintly not me, then who?

7 Page 19 from the book GRAVITATION

The purpose of the first 19 pages of Gravitation is not to compare Newton with Einstein. You should read and understand better what it is written there before spouting nonsense.

>	What is fair is when you compare a simulation (all planets around the sun) using the theories of both scientist to predict the future. In that sense each theory without any shortcut. See for example chapter 39. Nicolaas Vroom

Again, you take bit and pieces of a book without making the effort of understanding what it is being written (in that case the Post Newtonian Expansion)

8 Page 19 from the book GRAVITATION

> > >

It is really unfair to talk about a partial part of page 19 of that book, while totally ignoring the previous 18 pages, boxes and figures delivering the complete views and reasonings which justify the important conclusion of locality.

> >	It is IMO unfair when you compare two scientist based on the concept locality i.e. local inertial frames when one of the two does not use that concept but starts from a global coordinate system.

>	The purpose of the first 19 pages of Gravitation is not to compare Newton with Einstein.

All(?) the pages breathe this difference.

At page 4 Figure 1.1 almost show the same information. "In Newtonian theory this effect is ascribed to gravitation action at a distance from a center of atraction, symbolized here by the stem of the apple" In Newtonian theory each object gets an "action at a distance" by all the other objects considered. Each action follows a straight line. The reaction is that the path of the object is not straight.

"According to Einstein a particle gets its moving orders locally, from the geometry of space time right where it is." According to Newton each object gets its orders instantaneous from all the objects considered.

"Its instructions are simple: to follow the straigtest possible track (geodesic)" I expect that these instructions (very bad wording) are extremely complex.

>	You should read and understand better what it is written there before spouting nonsense.

In some sense the more I read in the book GRAVITATION the less I understand. See also below.

> >	What is fair is when you compare a simulation (all planets around the sun) using the theories of both scientist to predict the future. In that sense each theory without any shortcut. See for example chapter 39.

>	Again, you take bit and pieces of a book without making the effort of understanding what it is being written (in that case the Post Newtonian Expansion)

Paragraph 39.9 "Velocity of PPN coordinates relative to Universal Rest frame" here we read: "Thus far it is has been assumed tacitly that the center of mass of the solar system is at rest in the PPN coordinate system. Is this really a permissible assumption?"

What I try to understand is the evolution op the planet Mercury over a period of 10000 years.

Equation 39.64 is interesting. What you clearly can see is how complex GR is compared to clasic Newton.

At page 1096 you can read: "That spacetime geometry is very complicated. It includes the spherical fields of the sun and all the planets etc."

Read also the bottom part after *: "All these "individual fields" etc are the best abandoned (they cease to be useful) when one passes from the post_Newtonian limit to the full Einstein theory."

That is what I expect, when you want to calculate how the sun behaves in our galaxy using GR.

Nicolaas Vroom

9 Page 19 from the book GRAVITATION

You really have great difficulty in reading plain English. It is also clear from your reading you pick some text and totally ignore the context of the writing, as you show below.

>	At page 4 Figure 1.1 almost show the same information. "In Newtonian theory this effect is ascribed to gravitation action at a distance from a center of atraction, symbolized here by the stem of the apple"

You see? you picked a piece of the text ignoring even what the figure is about: The Riemnanian geometry of spacetime.

The ants are observed moving through the apple (worldline), which through the magnifying glass are seen as straigth lines (in 2D), while on the apple are geodesic tracks.

Then the text explains the observations according to Newtonian and Einstein theories. Nowhere are Newton and Einstein being compared as scientists.

>	In Newtonian theory each object gets an "action at a distance" by all the other objects considered. Each action follows a straight line. The reaction is that the path of the object is not straight.

This makes no sense and it is not what fig 1.1 says or represent.

>

"According to Einstein a particle gets its moving orders locally, from the geometry of space time right where it is." According to Newton each object gets its orders instantaneous from all the objects considered. "Its instructions are simple: to follow the straigtest possible track (geodesic)" I expect that these instructions (very bad wording) are extremely complex.

On the contrary, observations of Nature show how simple these instructions are in the universe: just follow a geodesic, that is the shortest path through spacetime, since that path is the path which uses the minimum energy.

> >	You should read and understand better what it is written there before spouting nonsense.

>	In some sense the more I read in the book GRAVITATION the less I understand. See also below.

> > >

What is fair is when you compare a simulation (all planets around the sun) using the theories of both scientist to predict the future. In that sense each theory without any shortcut. See for example chapter 39.

> >	Again, you take bit and pieces of a book without making the effort of understanding what it is being written (in that case the Post Newtonian Expansion)

>

Paragraph 39.9 "Velocity of PPN coordinates relative to Universal Rest frame" here we read: "Thus far it is has been assumed tacitly that the center of mass of the solar system is at rest in the PPN coordinate system. Is this really a permissible assumption?" What I try to understand is the evolution op the planet Mercury over a period of 10000 years.

¿?

10 Page 19 from the book GRAVITATION

> >	"Its instructions are simple: to follow the straigtest possible track (geodesic)"