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Offline Mw-theoritician

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the element of space?
« on: 14/03/2008 00:15:09 »
Does space itself have a structure, does it have an element or elements which to be comprised of??


 

Offline DoctorBeaver

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the element of space?
« Reply #1 on: 14/03/2008 08:03:07 »
Elements are made of atoms. Atoms are made of fundamental particles. They exist in space but are not the structure of it.

According to Quantum Field theory space is a seething mass of virtual particles that exist only for the tiniest fraction of a second.

Have a look here -> http://zebu.uoregon.edu/~imamura/209/apr14/virtual.html
« Last Edit: 14/03/2008 08:04:56 by DoctorBeaver »
 

Offline Mw-theoritician

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the element of space?
« Reply #2 on: 14/03/2008 16:11:43 »
so there is no physical and/or infinate structure of space itself,
 

Offline Mw-theoritician

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the element of space?
« Reply #3 on: 14/03/2008 16:17:29 »
oh, and your link was of great insight.
 

Offline DoctorBeaver

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the element of space?
« Reply #4 on: 14/03/2008 19:09:32 »
so there is no physical and/or infinate structure of space itself,

There is no physical structure as such; just the mass of virtual particles. Whether space is infinite or not is a different question.

Glad the link helped.
 

Offline lightarrow

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the element of space?
« Reply #5 on: 15/03/2008 13:04:35 »
so there is no physical and/or infinate structure of space itself,

There is no physical structure as such; just the mass of virtual particles.
I'm not sure if we could state there is no physical structure; certainly, not physical in the sense of containing matter, but physical in the sense it can have some structure and in the sense it can affect matter. According to GR, a massive rotating object, for example, drags spacetime around itself, affecting the motion of bodies (including light) in its proximities. This effect, IIRC, should have been recently confirmed from the Gravity Probe experiment.
 

Offline Soul Surfer

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the element of space?
« Reply #6 on: 15/03/2008 13:32:03 »
The ultimate structure of space-time is a matter of considerable discussion.  There are several ideas around and whether any one of them will or can ever be proved and tested is  quite uncertain.

Let us start with the uncertainty principle and virtual particles.  this shows how the universe works on a moderately large scale and low energy (!!  yes I really do mean this)  The likely sales at which quantum space time is likely to show itself is much tinier and by implication much higher energy than any of the virtual particles that we have been talking about up til now.  To follow on with the virtual particle ideas we could therefore visualise it as the appearance and evaporation of vast numbers of tiny black holes.

Thinking of it in a more static image it could be that space-time is a bit like a crystal structure and much more geometric.

There is one important that is often ignored fact is often forgotten and one that I personally feel has an important role to play that is the effect of angular momentum or turbulence in this. other people notably roger penrose have considered this and come up with the idea that space time could be a spin networks in which the geometrical meshes of a crystal structure consit of a web of rotations along axes that are in some way quantised

I personally tend to favour something like this and feel that vortexes like this are the strings that form string theory.
 

Offline DoctorBeaver

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the element of space?
« Reply #7 on: 15/03/2008 20:27:03 »
so there is no physical and/or infinate structure of space itself,

There is no physical structure as such; just the mass of virtual particles.
I'm not sure if we could state there is no physical structure; certainly, not physical in the sense of containing matter, but physical in the sense it can have some structure and in the sense it can affect matter. According to GR, a massive rotating object, for example, drags spacetime around itself, affecting the motion of bodies (including light) in its proximities. This effect, IIRC, should have been recently confirmed from the Gravity Probe experiment.

But can it be said that simply because it can affect matter, it has structure?
 

Offline DoctorBeaver

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the element of space?
« Reply #8 on: 15/03/2008 20:30:23 »
other people notably roger penrose have considered this and come up with the idea that space time could be a spin networks in which the geometrical meshes of a crystal structure consit of a web of rotations along axes that are in some way quantised


I've heard of & read about spin networks but, I have to admit, I don't really understand it.
 

Offline lightarrow

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the element of space?
« Reply #9 on: 15/03/2008 22:01:42 »
I'm not sure if we could state there is no physical structure; certainly, not physical in the sense of containing matter, but physical in the sense it can have some structure and in the sense it can affect matter. According to GR, a massive rotating object, for example, drags spacetime around itself, affecting the motion of bodies (including light) in its proximities. This effect, IIRC, should have been recently confirmed from the Gravity Probe experiment.
But can it be said that simply because it can affect matter, it has structure?

It depends on how we want to define the word "structure" in this context; what do you propose?
 

Offline DoctorBeaver

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« Reply #10 on: 15/03/2008 22:13:28 »
I'm not sure. Tangible, maybe?

This is from Google:-

Definitions of structure on the Web:

    * a thing constructed; a complex entity constructed of many parts; "the structure consisted of a series of arches"; "she wore her hair in an amazing ...
    * the manner of construction of something and the arrangement of its parts; "artists must study the structure of the human body"; "the structure of the benzene molecule"
    * the complex composition of knowledge as elements and their combinations; "his lectures have no structure"
    * a particular complex anatomical part; "he has good bone structure"
    * social organization: the people in a society considered as a system organized by a characteristic pattern of relationships; "the social organization of England and America is very different"; "sociologists have studied the changing structure of the family"
    * give a structure to; "I need to structure my days"
      wordnet.princeton.edu/perl/webwn

    * The structure of something is how the parts of it relate to each other, how "it is put together". This contrasts with process, which is how the things change.
      en.wikipedia.org/wiki/Structure

    * In mathematics, progress often consists of recognising the same structure in different contexts - so that one method exploiting it has multiple applications. ...
      en.wikipedia.org/wiki/Structure (category theory)

    * In mathematical logic, a structure is an object that gives semantic meanings to the symbols in a logical language. The most common setting is with first-order languages, but structures for typed and higher-order languages are also important.
      en.wikipedia.org/wiki/Structure (mathematical logic)

The definition from Wikipedia "The structure of something is how the parts of it relate to each other" could possibly incorporate a structure of space.
 

Offline lightarrow

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the element of space?
« Reply #11 on: 16/03/2008 00:14:12 »
Ok.
Let's talk about flat spacetimes, for simplicity. An element of it is (cdt,dx,dy,dz), another different element is (cdt',dx',dy',dz'). Are the two elements connected in some specific way?

mumble, mumble, mumble...

yes!

(cdt)2 - (dx)2 - (dy)2 - (dz)2 = (cdt')2 - (dx')2 - (dy')2 - (dz')2.

That's the structure.
 

Offline DoctorBeaver

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the element of space?
« Reply #12 on: 16/03/2008 08:22:39 »
Yeah, in a mathematical sense. But what most people would understand as structure does not exist.
 

Offline lightarrow

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the element of space?
« Reply #13 on: 17/03/2008 08:15:59 »
Yeah, in a mathematical sense. But what most people would understand as structure does not exist.

So, do they only understand Structure = made of matter?
 

Offline DoctorBeaver

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the element of space?
« Reply #14 on: 17/03/2008 20:36:31 »
Probably
 

Offline Soul Surfer

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the element of space?
« Reply #15 on: 18/03/2008 09:31:53 »
Light arrow   you are using simple calculus to talk about the GEOMETRY of spacetime.  That is simple classical continuous space relatavistic stuff.  The problem comes when you want to quantise it.

The two approaches that I mentioned were firstly a heap of particles that occupy space and secondly a network of lines that define it.  It may of course be both at the same time.

From our point of view space and time are totally linked together and the "size" of our universe is totally determined by how fast light moves.

Quantum and string theory has properties that suggest that the universe is really tiny in most of its many dimensions and the "space" that we are so familiar with might just be a local quirk or illusion!
« Last Edit: 18/03/2008 09:43:50 by Soul Surfer »
 

Offline lightarrow

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the element of space?
« Reply #16 on: 18/03/2008 19:04:10 »
Light arrow   you are using simple calculus to talk about the GEOMETRY of spacetime.  That is simple classical continuous space relatavistic stuff.  The problem comes when you want to quantise it.
Do you mean that spacetime woudn't have a structure if Planck's constant h were 0?
I'm not sure, but I think geometry is the structure.
 

Offline DoctorBeaver

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the element of space?
« Reply #17 on: 18/03/2008 19:09:24 »
*sits back to watch Ian & Alberto fight this 1 out*
 

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