The Ontology of Space Time - Edited by Dennis Dieks 2006 - Article review

This document contains article review "The Ontology of Space Time" Edited by Dennis Dieks in 2006
To order to read the article select: https://www.academia.edu/5444089/The_disappearance_of_space_and_time

• The text in italics is copied from the article.
  
• Immediate followed by some comments
  

Contents

• Introduction page ix
• Chapter 1. "The Implications of General Covariance for the Ontology and Ideology of Spacetime" by John Earman - page 3
• Chapter 2. "The Disappearance of Space and Time by Carlo Rovelli." - page 25
• 2.
• 3.

Reflection

• Reflection 1 - Physics versus Philosophy.
• Reflection 2 -

The nature of space and time is a traditional philosophical subject.

Whether space is an independently existing "substance" or not, and whether time is a measure of change in material processes or rather something that exists and "flows" even if there are no material processes going on, are questions that go back to the very beginnings of natural philosophy.

Also this was correct, but it is not anymore.

But in spite of this longevity no consensus has been reached, and these issues are still exercising the minds of both scientists and philosophers.

It should be understand that time and space are primarily physical issues and should be discussed by scientists.
Their first task should be to define these physical concepts as clear as possible.
As such space is not a substance equivalent to matter. At the same time space is not empty.

This is due to a number of factors.

One of these factors is the importance of a clear definition of all words and concepts used. Consider the following words in the text:
substantivalism, relationalism, "hole argument", diffeomorphism, manifold points, the state of the universe, spacetime points, ontological furniture, ontology of spacetime.

Another reason for the interest in spacetime questions is the awareness that the global temporal structures exhibited by solutions of the general relativistic field equations are very relevant to debates about the nature of time.

First you need a clear description of what "the nature of time" means, other wise any discussion about GR does not make sense.
A phylosophical issue is to what extend solutions of GR field equations can be used in this respect.
The main reason is that mathematics first has to be demonstrated as a valid description of a particular process.

In particular, the notorious question of whether it makes sense to say that there is "becoming", or that "time is flowing", has received a new impetus from this direction

The same is true with the therminology: "becoming" and "time is flowing".

Page x

In the 1940s, Gödel published a number of seminal papers in which he demonstrated the existence of solutions of the Einstein equations in which closed time-like curves occur (Gödel, 1949).

This sentence to understand, at least must require a clear definition of what "closed time-like curves" are. Anyway it is not my understanding that "closed time-like curves" are not something physical.

The surge of interest in questions of this kind has made the need felt for a permanent international platform on which philosophers and scientists can meet and engage in fundamental discussions.

The above subjects discussed are heavily physical detailed. IMO the most important participants are phycists.

As already mentioned, the ontological debate par excellence is between those who take space and time to be independent substances, and those who maintain that space and time are mere representational devices, introduced by us to order the spatial and temporal relations between physical systems.

To discuss this sentence you first of all need a clear definition of what a substance is. The classical definition is, that the both matter and substance are "equivalent". Neither space and time are substances. Time is nothing physical. Time is much more a human experience. Physical processes evolve in time. But that does mean that time is something that exists. What exists are clocks. A clock is a physical device, it functions as an oscillator.

Think, in order to have a concrete example, of a system of classical point particles: the substantivalist will argue that these particles occupy points in absolute space, and that the distances between these spatial points induce distances between the particles.

The only thing you can claim is that at any moment in time, the whole universe consists of a collection of physical objects. What you also can do, is to define a coordinate system. Using such a coordinate system you can also claim that at any moment in time each each physical object has a position x,y,z.

By contrast, the relationist will hold that the particles possess distances with respect to each other directly, i.e. without the intervention of an underlying space, and that Newtonian space only furnishes a mathematical representation of these physical distance relations.

The understanding what the difference is between a substantivalist and relationist is not clear.
As I mention, at any moment in time, all objects have a certain position in space. The positions change 'in due time', as such such each position should be described as x,y,z and by a fourth parameter t. t being the universal time, which is valid for the whole of the universe.
The whole idea is to measure the positions of all objects, at any moment in time. However that is not realistic. What is realistic, but that is still very difficult, is to measure the position of the Sun and all the planets, in one reference frame, at a sequence of moments, for example each hour apart.
When you have done that you can calculate the masses of these objects, using Newton's Law. The most important question is: is Newton's Law accurate to do that? The next step, is when you have defined the masses of all these objects, is to calculate the positions of these objects in the future.

Page xi

In the case of field theories, the relationist has to assume that elementary field-parts possess spatial relations with respect to each other, and that there are coincidence relations between the parts of different fields.

An apple falls from a three. The question is: What is the physical explanation of this process. One explanation is that both are atracted towards each other and that there is a force involved between both. But that introduces a new question: what is this physical force?
A different explanation is to introduce a field. But that raises a new question: What exactly is a field? Is it something physical or mathematical
It should be understand that speed and acceleration are also mathematical concepts. They are calculated using a ruler and a clock.

Page xv

3.

4.

To understand the processes that take place in the univerese, here on earth we call science specific physicsal science. One specificical branch is chemical science. As such physics is the science to understand the physical processes that take place here on earth, specific the evolution of these processes.
One important way to do physics is by performing observations and by performing experiments. It is not the purpose of this reflection to discuss this.
The question we want to adress is: what are the ground rules to do proper science i.e to do physics and chemistry. This is the field of study of the philosophers. My opinion is that if you want to do science all the words used should be clearly defined and all the sentences should be as simple as possible. This makes it much easier for your opponent, in a discussion, to repeat what you have said. It also makes it much easier to define about which you both agree.

Now we go back to my answer on the first sentence in the introduction: "The nature of space and time is a physical subject." See: page ix
Some people can answer: The concept discussed is wrong. The should be "The nature of space-time is a physical subject.". That immediate points out how important physics is. That means it is much more important than philosophy and that the primary field of study to discuss this subject, should be physics.

How ever I want to mention that if you really want to understand physics you should take the philosophical approach.

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