From: tjroberts137@sbcglobal.net   
      
   On 7/17/18 2:55 PM, Nicolaas Vroom wrote:   
   > The idea is when we try to perform the same experiment the descriptions and   
   > the results should be the same. (repeatability)   
      
   Yes, repetitions should reproduce results.   
      
   > You can ofcourse only do that when you remove everything what is observer   
   > dependent. The description (model) should be observer independent. My   
   > observations are subjectif. The descriptions should be objectif.   
      
   In general, observer-independent descriptions are pretty useless. People nearly   
   always use coordinates to describe experiments and their results.   
      
   > They are subjectif (If that is the correct defintion)   
      
   English: subjective: based on or influenced by personal feelings, tastes, or   
   opinions; in physics: coordinate dependent.   
      
   As opposed to objective: not subjective; in physics: coordinate independent.   
      
   > But the real description should be observer independent.   
      
   Descriptions by observers are "real" (in any useful meaning of the word).   
      
   The PHYSICS is observer dependent, but descriptions are usually not.   
      
   > This requires a certain transformation to come to one common description. An   
   > objectif description.   
      
   For the situation being discussed (stone dropped on moving train), an objective   
   description is: the stone follows a geodesic in spacetime (neglecting air);   
   another would be a list of successive spacetime points it occupies (but that is   
   very difficult to do without coordinates). Those are pretty useless, compared   
   to   
   the descriptions by the observers (given earlier).   
      
   > But for me physical laws are equivalent to descriptions. A different name is   
   > model or mathematical equations.   
      
   The phrase "physical law" is self-inconsistent and ambiguous: "physical"   
   implies   
   it is related to the world, while "law" is clearly part of the model.   
      
   Some people use "physical law" to mean the (unknown) methods nature uses in the   
   operation of the world. Other people, like you, use it to mean the models we   
   humans have collected that describe how the world works. Both are acceptable   
   and   
   common usage, but one must be clear about which is being used.   
      
   > I prefer a clear distinction between observation (me) and a description   
   > (we).   
      
   Such peculiar usage is hopeless, as others will not know what you mean.   
   Personal   
   vocabularies are confusing (to you and to others); they generally are an   
   attempt   
   to disguise a misunderstanding on the part of the user.   
      
   An aspect of your misunderstanding is:   
   > The coordinates used as part of the model should be human independent.   
      
   That is simply not possible: coordinates are ARBITRARY human constructs.   
      
   	All humans might agree on the definition of a coordinate system,   
   	so in one sense that is "human independent", but it still   
   	depends in essential ways on humans. Nature does not depend on   
   	humans at all.   
      
   > What we humans want is to understand how nature operates.   
      
   "Understand" in the sense of "model". As our minds process only thoughts, this   
   is the best we humans can do.   
      
   >> We have CHOSEN to use different models for gravitation and   
   >> electrodynamics.   
   >   
   > Because these processes are physical different and require different laws.   
      
   What God whispered in your ear and told you this? -- because that is the only   
   way you could know it.   
      
   To be clear: we humans have divided the world into different domains, one in   
   which our model of electrodynamics is valid, and a different domain in which   
   our   
   model of gravitation is valid. Nature recognizes no such separation and no such   
   domains -- she operates freely throughout the entire world and does whatever it   
   is that she does. We humans have been forced by our limited knowledge into this   
   separation, and are fortunate to have discovered separate models of   
   electrodynamics and gravitation (and their corresponding domains); thinking   
   this   
   separation also applies to nature is completely unwarranted, and likely wrong.   
      
   > [... further variations on divine knowledge (gravitons vs photons, ...)]   
      
   Tom Roberts   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)