What is Space made of?

[Mordred]

yes mass is resistance to inertia change so your common relation is momentum and factors that affect change in momentum. The stress tensor doesn't identify the cause but describes the influence to momemtum. Energy is "the ability to perform work." This all relates back to your Newton laws of inertia under a collective organization in your stress tensor. Spacetime curvature itself is a geodesic map of freefall motion. Described as the particles worldline.

 

The stress tensor gives us the momentum based components of that map.

 

So literrally any dynamic/interferance or interaction that can induce a resistance to inertia change is a form of mass. These are described under the stress tensor.

Edited January 25, 2017 by Mordred

[Tom O'Neil]

@ Mordred

Can I ask are you trying to write a unified field equation, which unites quantum gravity to macro gravity?

Edited January 25, 2017 by Tom O'Neil

[Mordred]

@ Mordrid

Can I ask are you trying to write a unified field equation, which unites quantum gravity to macro gravity?

Not at this point the problem with quantum gravity lies within a term called "renormalization" which is a very complex topic. Part of the problem with renormalization lies within the Heisenburg uncertainty principle itself.

 

Just to be clearer there, when you hear the term "the problem is quantization" A quanta is the nimimum energy to cause "observable action". Action is a term to describe kinematic motion. Whats often described as a virtual particle for example cannot perform action as it is less than a quanta.

 

The term particle itself is a classical misnomer as all particles are a field excitation. A field being a collection of excitations in this case. A field deviod of excitations being what is termed your zero point energy in QM. Under Cosmology true vacuum. However the Heisenburg uncertainty principle causes difficulty even after all excitations are removed. An excitation being a quanta, a fluctuation being VP of energies less than a quanta. I'm being a bit heuristic but this is where the problem lies between quantum gravity and relativity for a full blown TOE.

Edited January 25, 2017 by Mordred

[Tom O'Neil]

Have you ever got light headed and seen stars or floaters. I often wondered why I can see them turn on an angle of about 30° every time. I even pondered if my own biology is seeing actual electrons or is that a false belief? Measuring electrons in time and position must still be a major problem as in uncertainty. If we knew the path that a electron takes and if it is consistent we could find its position at a point in time.

 

 

Edited January 25, 2017 by Tom O'Neil

[Mordred]

Ok good images I can distinquish the problem using these. The external lines are your excitations (particles) these are termed your real particles. The internal ziggly lines on the right image is your fluctuations (virtual particles) it is those internal lines that is the issue.

 

The external lines are renormalizable the internal lines are not. The external lines can induce effective action. While the internal lines has insufficient energy to do so. This is all described under S-matrix theory. Lattice QCD shows that an external line is really a boundary confined collection of fluctuations(VP) that sum up under confinement to an excitation.

(particle)

Spots in your eyes are more a biology discussion. I don't know the proper terminology but in essence your receptors are still sending delayed signals

Edited January 25, 2017 by Mordred

[Tom O'Neil]

Spin has to be a property here. The field may increase and decrease as the electron traverses a path. Perhaps the internal lines impede the external lines like resistance which would cause the field to vary. Or do we even know if the electron wobbles as in it does not make a full revolution?

 

If the internal are virtual then that statement maybe incorrect yet do they have any cause and effect value?

Edited January 25, 2017 by Tom O'Neil

[Mordred]

Spin is a property but one that is quantized. A VP being "off shell" may or may not exhibit spin. The minimum measurable quantizable value is [latex] E=\hbar w [/latex]. In QFT this defines the creation/annihilation operators (math term). The reason a VP isn't measurable is that they have insufficient energy to cause action to affect even the most ideal detection instrument.

Edited January 25, 2017 by Mordred

[Tom O'Neil]

Listening to Feynman rite now:)

[Mordred]

Feyman has excellent lectures. I would ask any further questions not directly related to "what is space" please start another thread I'll be more than happy to reply there. I don't want this thread to describe the body of physics 😉

Edited January 25, 2017 by Mordred

[Tom O'Neil]

@Mordred

The electron is not spherical and I'm not implying you said that! They are egg shaped according to this article. This tells me they are built for speed which is obvious. The field then could resemble waves extending from the electron which have some semblance to the electron. The angle the electron takes I believe is consistent; for in the field other electrons exist and if they are at the same valence shell then that angle is similar there. Next shell a greater angle!

 

 

http://io9.gizmodo.com/5805610/what-do-electrons-look-like-now-we-know

 

Edited January 25, 2017 by Tom O'Neil

[Strange]

Electrons are point particles and so have no shape. This is the challenge of reading popular science articles!

[studiot]

Not purely mathematical they are in essence fluid dynamic terms.

flux is particles/unit area/unit time) across surfaces of constant x, y and z.

Vorticity is a type of motion of those particles often described as the curl component. In essence describing rotational fluids. Classical examples being whirlpools etc. The curl component of the Maxwell equations being another example of vorticity. In essence vorticity is your angular momentum terms. Angular momentum being skew-symmetric

 

Isn't referring to 'fluid dynamics' a bit limiting?

 

How about Continuum Mechanics which includes FD and much more besides?

 

I say this because there are many texts at many levels including this in the title.

 

Edited January 26, 2017 by studiot

[Mike Smith Cosmos]

Isn't referring to 'fluid dynamics' a bit limiting?

 

How about Continuum Mechanics which includes FD and much more besides?

 

I say this because there are many texts at many levels including this in the title.

 

Why did you guys not bring this up when I was asking about the content and/or the structure of Space . Painfully I was taught DIV , GRAD , CURL . At Uni a couple of times as part of trying to get to grips with Maxwells equations and his proof around light and its speed.

 

When I brought it up . Then you were leading me along the line " there is no content , to space ! ". You all said , or words to that effect.

 

There must be something 'there' , if you can do an operation on it , like Div, Grad , and Curl ?

 

Mike

Edited January 26, 2017 by Mike Smith Cosmos

[studiot]

Why did you guys not bring this up when I was asking about the content and/or the structure of Space . Painfully I was taught DIV , GRAD , CURL . At Uni a couple of times as part of trying to get to grips with Maxwells equations and his proof around light and its speed.

 

When I brought it up . Then you were leading me along the line " there is no content , to space ! ". You all said , or words to that effect.

 

There must be something 'there' , if you can do an operation on it , like Div, Grad , and Curl ?

 

Mike

 

Not sure why you are replying to me, Mike?

 

 

I don't recall ever discussing grad, div & curl with you.

[Mike Smith Cosmos]

Not sure why you are replying to me, Mike?

 

 

I don't recall ever discussing grad, div & curl with you.

May be you were not in on it , Eric .

I will need to dig out the topic . It was probably to do with Gravity and the nature of Space , so that gravity waves get propogated across space . And I was asking ? What was the substance of space , such that waves could be propagated.

 

I think I was 'left for dead ' , when I could not get my head round , that there was nothing there in ' space time ' .,unless you are saying the same . But it sounds like you and Maudred are saying that space time can be ( Div, Grad, and Curled ) . Or have I got it wrong a second time ?

 

Mike

[Mordred]

 

Isn't referring to 'fluid dynamics' a bit limiting?

 

How about Continuum Mechanics which includes FD and much more besides?

 

I say this because there are many texts at many levels including this in the title.

 

Sure you can use those terms. The majority of the textbooks though on GR and Cosmology will use the term fluid to denote the perfect fluid equations. A full study will reveal that that the majority of your advanced equations have a thermodynamic basis.

Why did you guys not bring this up when I was asking about the content and/or the structure of Space . Painfully I was taught DIV , GRAD , CURL . At Uni a couple of times as part of trying to get to grips with Maxwells equations and his proof around light and its speed.

 

When I brought it up . Then you were leading me along the line " there is no content , to space ! ". You all said , or words to that effect.

 

There must be something 'there' , if you can do an operation on it , like Div, Grad , and Curl ?

 

Mike

Mike those terms are used once you have a stress tensor. Space by itself with all excitations/particles removed is just your metric tensor. Your geometry .

 

The metric tensor being [latex]g_{\mu\nu}[/latex]

 

in the above conditions there is no active stress tensor [latex]T_{\mu\nu}=0 [/latex]

 

In your other thread you wanted to apply an ether or medium to space itself which is false as that is just your geometry. You have no medium like properties unless you have other fields other than just geometry.

 

This is an incredibly important distinction. ie there is no Div,Grad or Curl if the stress tensor is zero.

 

The key distinction is that space all by itself isn't a medium,fluid or ether. It is just the geometry. Once you add other fields such as force fields/particles you now have a stress tensor involved and can have medium like characteristics.

Edited January 26, 2017 by Mordred

[StringJunky]

Sure you can use those terms. The majority of the textbooks though on GR and Cosmology will use the term fluid to denote the perfect fluid equations. A full study will reveal that that the majority of your advanced equations have a thermodynamic basis.

Mike those terms are used once you have a stress tensor. Space by itself with all excitations/particles removed is just your metric tensor. Your geometry .

 

The metric tensor being [latex]g_{\mu\nu}[/latex]

 

in the above conditions there is no active stress tensor [latex]T_{\mu\nu}=0 [/latex]

 

In your other thread you wanted to apply an ether or medium to space itself which is false as that is just your geometry. You have no medium like properties unless you have other fields other than just geometry.

 

This is an incredibly important distinction. ie there is no Div,Grad or Curl if the stress tensor is zero.

 

The key distinction is that space all by itself isn't a medium,fluid or ether. It is just the geometry. Once you add other fields such as force fields/particles you now have a stress tensor involved and can have medium like characteristics.

It's the phenomena that's occuring between things that creates the patterns.

[Mordred]

lol very true

[StringJunky]

lol very true

it helps remove the idea of a medium, doesn't it? It'll be a lot easier for us neophytes when QG is sorted, with virtual particle exchange as the process rather than warping geometry.

 

Will spacetime still be a feature in a quantum gravity model?

[Mordred]

Of course, spacetime is incorperated in very deifinition of a particle itself when you get into the QFT treatment of a particle. You literally cannot describe a particles wavefunction without spacetime

Edited January 26, 2017 by Mordred

[Mike Smith Cosmos]

Of course, spacetime is incorperated in very deifinition of a particle itself when you get into the QFT treatment of a particle. You literally cannot describe a particles wavefunction without spacetime

.

So you are sort of saying ' something else provides the STRESS TENSOR . And if it is set up by whatever , it becomes a Quantum Field , which has its own characteristics of Quantum Field Theory , which might well include. DIV , GRAD , and CURL.

 

So in my case with radio waves and presumably including light waves , the div, grad and curl describes the state of curled space provided by the originating photon emission . And with gravity waves I presume something massive doing a bit of a move provides its own perculiar Div , Grad. And Curl .

 

I sort of get a better picture now , if this is it . I suppose the tensor is just one of the components .

 

I still have this slight disquiet about ' what quite is being ' tensed, curved, curled etc . If we say it is the geometry of space that is being affected . I will just have to accept that.

 

I just have a slight , shadowy ' niggle '

 

Mike

Edited January 26, 2017 by Mike Smith Cosmos

[Mordred]

Pretty good your getting the picture now congrats I know how troublesome thats been for you +1

Edited January 26, 2017 by Mordred

[Mike Smith Cosmos]

Pretty good your getting the picture now congrats I know how troublesome thats been for you +1

.

I think a little bit more on the ' STRESS TENSOR/ ' s , would help me expell my ghosts . Not so much in mathmatical terms but in language or analogy form , would be absolutely great if you could Mordred. Then maybe , I can be put down to rest . ( for a little while at least ) .

 

I don't suppose I am the only person who has struggled with this particular aspect of ' space time ' .

 

Mike

Edited January 27, 2017 by Mike Smith Cosmos

[StringJunky]

Of course, spacetime is incorperated in very deifinition of a particle itself when you get into the QFT treatment of a particle. You literally cannot describe a particles wavefunction without spacetime

Right.

[Mordred]

.

I think a little bit more on the ' STRESS TENSOR/ ' s , would help me expell my ghosts . Not so much in mathmatical terms but in language or analogy form , would be absolutely great if you could Mordred. Then maybe , I can be put down to rest . ( for a little while at least ) .

 

I don't suppose I am the only person who has struggled with this particular aspect of ' space time ' .

 

Mike

 

 

Fair enough, lets play toy model. Lets assume a condition with no Heisenburg uncertainty principle. No field excitations/particles. (lets be 100% clear on below I am not trying to describe how a Universe is created or a Universe from Nothing model) so don't even go there I am strictly describing known physics in a heuristic manner. (specifically space-time under GR)

 

The only thing left is strictly volume. In GR this volume which is assigned coordinates as the volume is 3 dimensional that volume requires 3 coordinates. x,y and z. We can include time as the fourth coordinate t.

 

this is literally Space-time. Space being the three spatial coordinates with time as the fourth coordinate. As we have nothing to interact with the effective energy of this Space-time is literally zero.

Now lets include some basic physics definitions.

 

Energy: The ability to perform work.

Mass: Resistance to inertia change

potential energy: the energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors.

Field: An abstract device to describe any collection of objects/coordinates/events.

 

So using the definition of a field I can describe the space-time coordinates as a field. However as I have no interactions involved the field energy is precisely zero. There is literally no stress tensor as coordinates are not moving without an interaction. All I have defined thus far is the metric tensor [latex]g_{\mu\nu}[/latex]. Now as I have no stress tensor, nor any anistropy ( differences in potential energy) Our Space-time is Euclidean (flat)

there is no curvature in distribution. [latex]\eta_{\mu\nu}=g_{\mu\nu}[/latex]

 

Now if I add a single particle the particle doesn't interact with coordinates. Coordinates are strictly an abstract construct. So our potential energy still remains zero.

 

Analogy Time: lets use an everyday example. The electromagnetic field. Lets take your Voltmeter and in a vacuum move the + and - prongs onto two points of a bare wire ( assume the wire is a perfect conductor). You will measure zero volts. GR is no different if you have no potential difference {resistance} you have no voltage. A magnet itself however is a charged field. It has an inherent difference between the south and North pole. Think of Space-time itself with no interactions as an Uncharged field. There is no potential difference in any coordinate as we have no particles as of yet.

 

Once I add two or more particles this is where things get interesting. Now I have interactions, I can now assign those coordinates to each particle and call these individual events. As we have interactions between two or more objects I now have potential energy. My space-time field is now charged. However the charge is strictly the interactions between the particles not the geometry itself. In GR however we can assign each particle as an event and assign those event coordinates to the particles.

 

Now the above electromagnetic field is described by the Maxwell equations. Those Maxwell equations also can be described as as tensor (electromagnetic stress tensor) The stress tensor for GR is the exact same principle. In both cases the stress tensor is describing your kinematic vectors. ie flux. curl,div etc. They are identical in principle the only difference lies in the particular differences between gravity and the electromagnetic field ie Gravity only attracts while the electromagnetic field can attract and repel. In essence you stress tensor is a means to organize your different momentum vectors.

 

We can equally assign different coordinates to different points in your electro-magnetic field however that doesn't mean those coordinates gain a medium quality. The electromagnetic field itself not its coordinate field is what exhibit the medium qualities.

 

So Spacetime curvature under GR is the collection of vector relations where we set the geometry as the free-fall motion.

 

A geodesic is describing a free fall motion at every coordinate with the use of vectors via the stress tensor between two points. This is what space-time curvature (under GR) is describing a collection of vectors at each coordinate. In accordance to the Principle of least action (kinematic motion under free fall).

 

This is also why we use inertial frames in SR (key word inertial)

 

Now a medium induces further delays in the kinematic motion of two particles. So if space-time was a medium we would have further delays. It would be the same as placing additional resistance to the electromagnetic example above. Recall the word Impedance in your electromagnetic theory. Mass is a form of impedance it is impedance to kinematic motion. impedance=resistance.

 

Now using the electromagnetic field once again. You may recall that two circuits with two electromagnetic fields can induce impedance upon each other (propogation delay) we can describe these delays via coordinate time if we assign coordinates to each point of each field. See where I am going with in time dilation ?

 

If every particle is a field excitation then time dilation itself is by analogy a form of propagation delay. Just as it is in the electromagnetic field theory.

 

(keep in mind the above is a simpification) A heuristic rudimentary means to understand space-time under familiar terms. I won't try to show that gravity is not a force under GR using kinematic action as I know your not ready for that level of mathematical detail. However it does include everything I described above in particular the principle of least action under space-time curvature

Edited January 27, 2017 by Mordred