What is Space made of?

[Strange]

2 hours ago, Lizwi said:

Everything that exists

I would say that everything that exists, exists in space. It is not space itself.

[scarecrow_1]

Probably space made by nothing but that's not like our knows, we must find answer of 'whats that nothing' or how can we  contact with that

[StringJunky]

2 hours ago, Strange said:

I would say that everything that exists, exists in space. It is not space itself.

So, within the confines of a body, space does not exist? I know we commonly make the distinction but is that really the case?

[Strange]

3 minutes ago, StringJunky said:

So, within the confines of a body, space does not exist? I know we commonly make the distinction but is that really the case?

That isn't what I meant (but I can sort of see how it could be read like that). Within an object the space is filled by whatever the object is made of (wood, metal, blood, etc). Outside the object space is filled with air or interstellar medium or ... well, blood, maybe!

[StringJunky]

2 minutes ago, Strange said:

That isn't what I meant (but I can sort of see how it could be read like that). Within an object the space is filled by whatever the object is made of (wood, metal, blood, etc). Outside the object space is filled with air or interstellar medium or ... well, blood, maybe!

But are things really 'solid'?  

[Strange]

Just now, StringJunky said:

But are things really 'solid'?  

Depends how you define "solid" I guess.

Just noticed a thread title about measurement of volume, which made me think of Archimedes principle which captures what I am trying to say. If you have a metal sphere with a volume (ie a measure of the space it occupies) of 1m³, for example, and place it in water then it will displace the same volume of water from that space to the space outside the sphere.

[StringJunky]

1 minute ago, Strange said:

Depends how you define "solid" I guess.

Just noticed a thread title about measurement of volume, which made me think of Archimedes principle which captures what I am trying to say. If you have a metal sphere with a volume (ie a measure of the space it occupies) of 1m³, for example, and place it in water then it will displace the same volume of water from that space to the space outside the sphere.

I know, I was looking at it more fundamentally than our macro experience; space is a platform for fields.. Within those fields there is still space.

[swansont]

!

Moderator Note

More off-topic posts have been removed.

 

 

[tlo]

Here is my problem with the space or spacetime idea, we humans, we think of something and we give it a definition but then some other human thinks about the same thing and gives a new definition and this keeps going on and on, someone buys into the idea sets forth and strengthens that particular concept, then adds math theories to it and then somehow we get a new definition and then again it goes on and on, trying to win the battle of what is valid or true.

1. a continuous area or expanse which is free, available, or unoccupied.
2. position (two or more items) at a distance from one another.
3.  outer space, is the near-vacuum between celestial bodies. It is where everything (all of the planets, stars, galaxies and other objects) is found. 
4.  a boundless three-dimensional extent in which objects and events occur and have relative position and direction
5. a set of mathematical elements and especially of abstractions of all the points on a line, in a plane, or in physical space
6. a set of mathematical entities with a set of axioms of geometric character — compare METRIC SPACE, TOPOLOGICAL SPACE, VECTOR SPACE
7. .......

Now it's become this mystical spacetime 4th dimensional concept that is  a fabric that can be bent where macro object could then be warped a 10 times the speed of light to a new point. 

Edited October 27, 2019 by tlo
for got to complete the idea

[Strange]

59 minutes ago, tlo said:

we get a new definition and then again it goes on and on, trying to win the battle of what is valid or true.

That is why science doesn’t really deal with “truth”. 

It creates useful models to describe the world. There can be two or more “correct” models of something, which may even contradict each other. For example, in Newtonian mechanics & gravity, space and time are absolute and independent. That model works really well. 

But in relativity they are relative measurements and interdependent. That model can give more accurate results in some cases. 

There are models where space and time emerge from something else. 

1 hour ago, tlo said:

Now it's become this mystical spacetime 4th dimensional concept that is  a fabric that can be bent where macro object could then be warped a 10 times the speed of light to a new point. 

The model works. Using words like “mystical” doesn’t change that. 

[studiot]

2 hours ago, tlo said:

1. a continuous area or expanse which is free, available, or unoccupied.

etc

What is your list supposed to represent ?

Number 1 is  inadequate and untenable.

Are you suggesting space ceases to exist when it is 'occupied' and suddenly spring back into existence when the occupying object moves away?
What do you mean by continuous and why does it have to be continuous?
What do you mean by occupied? Does this include say, light? What happens when a ray of light passes from a vacuum into a glass block?

 

Hey I like this 11111 posts

Edited October 27, 2019 by studiot

[J.C.MacSwell]

1 hour ago, studiot said:

What is your list supposed to represent ?

Number 1 is  inadequate and untenable.

Are you suggesting space ceases to exist when it is 'occupied' and suddenly spring back into existence when the occupying object moves away?
What do you mean by continuous and why does it have to be continuous?
What do you mean by occupied? Does this include say, light? What happens when a ray of light passes from a vacuum into a glass block?

 

Hey I like this 11111 posts

Congratulations Studiot...on your 11111th post!

[MigL]

Don't know what you're so happy about.
You realize that's only 31 posts, don't you ?

[geordief]

8 hours ago, MigL said:

Don't know what you're so happy about.
You realize that's only 31 posts, don't you ?

That is a base accusation.

[studiot]

 

19 minutes ago, geordief said:

That is a base accusation.

9 hours ago, MigL said:

Don't know what you're so happy about.
You realize that's only 31 posts, don't you ?

 

Maya whispered in my ear that it was really 168421

+1 apiece.

[geordief]

45 minutes ago, studiot said:

 

 

Maya whispered in my ear that it was really 168421

+1 apiece.

Holy mother of Buddha,don't listen to Maya

 

https://www.ramakrishnavivekananda.info/vivekananda/volume_2/jnana-yoga/maya_and_illusion.htm

"Maya, Maya, all this world is but a play
Be thou the joyful player"

 

https://www.youtube.com/watch?v=SCRVkyt74Ig&list=RDSCRVkyt74Ig&start_radio=1

 

[Markus Hanke]

Greetings everyone, I am back 😎

So what is space made of? I think we need to first upgrade the question a bit and ask: what is spacetime made of? The answer to this is that it is a collection of events, to be understood in the sense in which the term is used in physics. To be even more exact, it is made of causal networks of events, i.e. events plus information about how those events are causally related. In terms of GR this is described as a manifold with its intrinsic geometry. Space on its own would then be just the spatial part of that network. So essentially, spacetime is a way to structure and organise information.

Looking at it this way opens up some interesting questions, not all of which fall under the remit of physics: exactly what kind of information underlies this concept? Can this same set of information be structured/modelled in other ways as well? Is this structure intrinsic to the information, or is it something we impose more or less arbitrarily? Etc.

P.S. It is important to remember that spacetime isn’t a physical “thing”, rather, it’s a mathematical model that captures certain aspects of the universe. It’s like a map we draw of a given territory.

[Mordred]

Welcome back and excellent post as always. I particularly agree with your caveat that spacetime is a mathematical model. 

[studiot]

4 hours ago, Markus Hanke said:

Greetings everyone, I am back 😎

So what is space made of? I think we need to first upgrade the question a bit and ask: what is spacetime made of? The answer to this is that it is a collection of events, to be understood in the sense in which the term is used in physics. To be even more exact, it is made of causal networks of events, i.e. events plus information about how those events are causally related. In terms of GR this is described as a manifold with its intrinsic geometry. Space on its own would then be just the spatial part of that network. So essentially, spacetime is a way to structure and organise information.

.

 

Yes welcome back. +1

This is (almost) Eddington's presentation.

4 hours ago, Markus Hanke said:

Looking at it this way opens up some interesting questions, not all of which fall under the remit of physics: exactly what kind of information underlies this concept? Can this same set of information be structured/modelled in other ways as well? Is this structure intrinsic to the information, or is it something we impose more or less arbitrarily? Etc.

P.S. It is important to remember that spacetime isn’t a physical “thing”, rather, it’s a mathematical model that captures certain aspects of the universe. It’s like a map we draw of a given territory.

However his answer to these follow up questions places the 'network' at the forefront ie the most important part of 'reality'.

What do you think

Edited December 7, 2019 by studiot

[Markus Hanke]

2 minutes ago, studiot said:

However his answer to these follow up questions places the 'network' at the forefront ie the most important part of 'reality'.

What do you think

It seems evident that if you had just a collection of events, without any causal relationships between them, then there would be no concept of 'spacetime' at all. So in that sense I agree, it is that interwoven network of relationships that turns a collection of events into a physically useful spacetime manifold. In practical and classical terms, you can put neighbouring events infinitesimally close together, and mathematically represent their relationships by endowing the manifold with a suitable connection and metric - which is pretty much what GR as a model does.

I emphasise again that this is a useful mathematical model, a map of the terrain so to speak, not a physical something to be found 'out there'. It's really important to understand this.

[Strange]

13 minutes ago, Markus Hanke said:

I emphasise again that this is a useful mathematical model, a map of the terrain so to speak, not a physical something to be found 'out there'. It's really important to understand this.

The “fabric” metaphor often leads people astray in this regard. 

(And welcome back!)

[studiot]

2 minutes ago, Markus Hanke said:

It seems evident that if you had just a collection of events, without any causal relationships between them, then there would be no concept of 'spacetime' at all.

Wouldn't it just be different?

Quote

Eddington

To put the contrast in another form, in our common outlook the idea of position or location seems to be fundamental. From it we derive distance or extension as a subsidiary notion, which covers part but not all of the conceptions we associate with location. Position is looked upon as the physical fact - a coincidence with what is vaguely identified by us as an identifiable point of space - whereas distance is looked upon as an abstraction or or a cmputational result calculable when the positions are known. The view we are going to adopt reverses this. Extension (distance, interval) is now fundamental; and the location of an object is a computational result summarising the physical fact that it is at certain intervals from other objects in the world. Any idea contained in the concept location whcih is not espressible by reference to distance from other objects, must be dismissed from our minds. Our ultimate analysis of space leads us not to a "here" and a "there" by to an extension such as that whi relates to "here" and "there". To put the conclusion rather crudely - space is not a lot of points close together; it is a lot of distances interlocked.

Accordingly our fundamentl hypothesis is that:-

Everything connected with location which enters into observational knowledge- everything we can know about the configuration of events- is contained in a relation of extension between pairs of events.

My italics/emboldening for emphasis.

 

[geordief]

59 minutes ago, studiot said:

 from Eddington

"The view we are going to adopt reverses this. Extension (distance, interval) is now fundamental; and the location of an object is a computational result summarising the physical fact that it is at certain intervals from other objects in the world. Any idea contained in the concept location whcih is not espressible by reference to distance from other objects, must be dismissed from our minds. Our ultimate analysis of space leads us not to a "here" and a "there" by to an extension such as that whi relates to "here" and "there". To put the conclusion rather crudely - space is not a lot of points close together; it is a lot of distances interlocked."

very interesting.Does that viewpoint apply to both SR and GR?

Looked at differently*, is it possible (in the model) to abstract space from spacetime by using   regions of spacetime where t equals a constant.?

When we look out at the night sky  is the picture we see such  a slice of spacetime ? ( a frozen point in spacetime)

 

* a different point ,actually(I think Markus touched on it  it in his earlier  post when he said "Space on its own would then be just the spatial part of that network" )

 

https://www.scienceforums.net/topic/89395-what-is-space-made-of/?do=findComment&comment=1124830

 

 

 

 

Edited December 7, 2019 by geordief

[studiot]

37 minutes ago, geordief said:

1) very interesting.Does that viewpoint apply to both SR and GR?

2) Looked at differently*, is it possible (in the model) to abstract space from spacetime by using   regions of spacetime where t equals a constant.?

When we look out at the night sky  is the picture we see such  a slice of spacetime ( a frozen point in spacetime)

 

3) * a different point ,actually(I think Markus touched on it  it in his earlier  post when he said "Space on its own would then be just the spatial part of that network" )

 

https://www.scienceforums.net/topic/89395-what-is-space-made-of/?do=findComment&comment=1124830

 

 

 

 

1) Yes it applies to both. The quote was actually from Eddington's "The Mathematical Theory of Relativity" - and it does get very mathematical, which covers both SR and GR.

The language is strangely more arcane than Einstein's, but he was a very clear thinker and likes to explain what he is doing and why.

He also wrote simpler book "Space, Time and Gravitation" with lots more words and rather less formal maths.

 

2) A very emphatic no I'm afraid. Dropping the coordinate idea of contours or isolines (t = a constant) is the most important idea both Marcus and Eddington stress.

The idea of t = a constant is dangerously close to leading towards an absolute coordinate system - an anathema to relativity.

3) Yes you can separate space and time but then you have immediately the same problem for both as in (2). You can regard the relations or links as like a building or fairground framework or better, the 'ball and stick' models of molecules in Chemistry. The events are the balls and the sticks are the realtions which are the relativistic invariants. Like the molecule, the configuration of the sticks alone, regardless of which way up they are, is fixed or the same. To take the analogy one step further. At the moleculer scale you can separate space and time and just consider the spatial configuration, without bringing in relativistic 'corrections'. But as soon as you get to the astronomic scale (solar systems, galaxies, etc) you have to either include the corrections or use a 4 D spacetime.
Swansont's work is intermediate between these and leads to small corrections most people don't know about or bother with.

Edited December 7, 2019 by studiot

[geordief]

21 minutes ago, studiot said:

1) Yes it applies to both. The quote was actually from Eddington's "The Mathematical Theory of Relativity" - and it does get very mathematical, which covers both SR and GR.

The language is strangely more arcane than Einstein's, but he was a very clear thinker and likes to explain what he is doing and why.

He also wrote simpler book "Space, Time and Gravitation" with lots more words and rather less formal maths.

 

2) A very emphatic no I'm afraid. Dropping the coordinate idea of contours or isolines (t = a constant) is the most important idea both Marcus and Eddington stress.

The idea of t = a constant is dangerously close to leading towards an absolute coordinate system - an anathema to relativity.

3) Yes you can separate space and time but then you have immediately the same problem for both as in (2). You can regard the relations or links as like a building or fairground framework or better, the 'ball and stick' models of molecules in Chemistry. The events are the balls and the sticks are the realtions which are the relativistic invariants. Like the molecule, the configuration of the sticks alone, regardless of which way up they are, is fixed or the same. To take the analogy one step further. At the moleculer scale you can separate space and time and just consider the spatial configuration, without bringing in relativistic 'corrections'. But as soon as you get to the astronomic scale (solar systems, galaxies, etc) you have to either include the corrections or use a 4 D spacetime.
Swansont's work is intermediate between these and leads to small corrections most people don't know about or bother with.

These invariant intervals ,can it be  usefully said that they are not subject to any uncertainty in their measurements?

 

If we picture them as"sticks" ,do they follow spacetime curvature? And they never "touch"? Would there be such a thing as relations between individual "sticks" (only "degrees of separation",perhaps ?)