Einsteinian Gravity

[Warped]

Recently a perplexing line of thought came to me that I cannot get rid of. There must be a fault in it somewhere but I can’t find it.

-Given: The effects of Einsteinian gravity are caused by a warping of spacetime, changing the geometry of space.

-Thus: The fact that space can be warped is an intrinsic characteristic of space itself.

-An object of mass approaching a larger mass has its momentum changed by encountering the warp caused by the larger mass, and proceeds to follow the topography of the contours of the larger warp, thus only appearing to being pulled.

-This occurs without any force. No force, no force carrier.

-Therefore, gravity cannot be quantized, there are no quanta involved in space itself.

[Silvestru]

9 minutes ago, Warped said:

-Given: The effects of Einsteinian gravity are caused by a warping of spacetime, changing the geometry of space.

Curvature of space-time not warp.

9 minutes ago, Warped said:

This occurs without any force. No force, no force carrier.

Technically it is a force. 
https://en.wikipedia.org/wiki/Fundamental_interaction

If you want you can keep it as "a consequence of the curvature of space-time".

And no, there is no quantum theory of gravity yet but that does not mean there is no carrier. We just don't know yet.

https://en.wikipedia.org/wiki/Graviton

Edited July 9, 2018 by Silvestru

[studiot]

11 minutes ago, Silvestru said:

Curvature of space-time not warp.

What leads you to say this?

 

19 minutes ago, Warped said:

An object of mass approaching a larger mass has its momentum changed by encountering the warp caused by the larger mass, and proceeds to follow the topography of the contours of the larger warp, thus only appearing to being pulled.

You may like to know that when a Physicist talks about a massive object she means, just 'an object with mass', not necessarily a large mass.

[Silvestru]

8 minutes ago, studiot said:

What leads you to say this?

I don't know. For me it's confusing to talk about warp of space time and not confuse with time-warp.

http://www.hawking.org.uk/space-and-time-warps.html

OP I assume was talking about the force of gravity.

Quote

Instead, one has to use technical terms, like closed time like curves, which are code for time travel. Although this lecture is partly about time travel, I felt I had to give it the scientifically more respectable title, Space and Time warps. Yet, it is a very serious question. Since General Relativity can permit time travel, does it allow it in our universe? And if not, why not. 

I am assuming the OP was not talking about time travel so I didn't want to get confused. 
Is this how the science community refers to the curvature of space-time? Space-time warp? I didn't know  

Edited July 9, 2018 by Silvestru

[studiot]

But here is a quote from your link

Quote

Hawking

The idea that space and time can be curved, or warped, is fairly recent.

As a matter of interest, the combination of the OP question and your reply has made me think of something quite deep about GR.

Edited July 9, 2018 by studiot

[Warped]

Silvestru, thank you for your reply. As your reference states, the Graviton is only hypothisized. In the current state of Physics there is no particle of gravity since an object of mass follows the contours of the warp and is not "pulled"and thus no chance of  success trying to apply quantum physics to gravity...yet.

[swansont]

2 minutes ago, Warped said:

Silvestru, thank you for your reply. As your reference states, the Graviton is only hypothisized. In the current state of Physics there is no particle of gravity since an object of mass follows the contours of the warp and is not "pulled"and thus no chance of  success trying to apply quantum physics to gravity...yet.

The curvature of spacetime is the classical explanation. Gravitons would be the quantum explanation, should such a theory be developed. 

We have classical vs quantum descriptions for electromagnetism, as well. Classical E&M have waves and the classical fields, while the quantum description has photons. The classical description did not preclude the quantum, per se. The quantum description is necessarily going to be different. 

[koti]

41 minutes ago, Warped said:

Recently a perplexing line of thought came to me that I cannot get rid of. There must be a fault in it somewhere but I can’t find it.

-Given: The effects of Einsteinian gravity are caused by a warping of spacetime, changing the geometry of space.

-Thus: The fact that space can be warped is an intrinsic characteristic of space itself.

-An object of mass approaching a larger mass has its momentum changed by encountering the warp caused by the larger mass, and proceeds to follow the topography of the contours of the larger warp, thus only appearing to being pulled.

-This occurs without any force. No force, no force carrier.

-Therefore, gravity cannot be quantized, there are no quanta involved in space itself.

When I first came into this forum I had a similar missconception which was straightened out by members here. Think of this not in terms of cause and effect instead think that spacetime curvature is gravity. Mass/Energy causes spacetime to curve and we perceive this curvature as gravity. 

„Curvature” and „Warping” are synonyms in this context but phycicists tend to use the term „curvature” 

21 minutes ago, studiot said:

As a matter of interest, the combination of the OP question and your reply has made me think of something quite deep about GR.

Tell us  

Edited July 9, 2018 by koti

[StringJunky]

10 minutes ago, koti said:

When I first came into this forum I had a similar missconception which was straightened out by members here. Think of this not in terms of cause and effect instead think that spacetime curvature is gravity. Mass/Energy causes spacetime to curve and we perceive this curvature as gravity. 

„Curvature” and „Warping” are synonyms in this context but phycicists tend to use the term „curvature” 

Yeah, it's more of a Yin-Yang relationship i.e circular rather than linear.  Mass-energy tells space how to bend and space tells mass-energy how to move.

[Silvestru]

30 minutes ago, studiot said:

But here is a quote from your link

As a matter of interest, the combination of the OP question and your reply has made me think of something quite deep about GR.

I fully agree that they are synonyms. Merriam Webster can help with that we don't need Hawking. But I just didn't want to get mixed up in subjects like the one posted by me.

Apologies for the small high-jack Warped.

[Warped]

I also agree that the spacetime warp IS gravity. But my point is that it does not involve a "Force" in the classical sense (i.e no force carrying particle is involved, like the hypothsized "graviton" ) therefore gravity CANNOT be quantized which makes the search for a "theory of everything"  a waste of time and effort..sort of like pissing up a rope. If all of this is in fact the case then a different theory of gravity may be needed to proceed on the quest.  (a little background here: I have no credentials. But I have just completed 19 video lecture courses* consisting of 465 lectures given by phd physicists and phd college professors on the topics of Astronomy, Quantum Mechanics, Gravity, General Relativity, Dark Matter -Dark Energy, Particle Physics, et cetera, ad nauseam....for a total of 233 hours. That plus a BS in Math. So, I have acquired only a minimum level of familiarity with the subject matter at college freshman level to bolster my posting.  I apologize for my verbosity.

* The Great Courses, published by The Learning Company.

[Markus Hanke]

2 hours ago, Warped said:

-This occurs without any force. No force, no force carrier.

-Therefore, gravity cannot be quantized, there are no quanta involved in space itself.

This doesn’t actually follow. Much like the other fundamental interactions, General Relativity can be written as a Yang-Mills gauge field theory, using the Ashtekar variables; it is thus quite natural to assume that spacetime is ultimately quantised, i.e. granular on small scales. We are in fact able to perform a full quantisation of this field theory, and the result is a model called Loop Quantum Gravity (LQG). This is currently a work in progress, since we do not yet fully understand all dynamics of this theory, and hence it is too early to tell whether it is a good description of quantum gravity, or not. Nonetheless, this model seems like a pretty strong contender.

There are also other clues that spacetime is not infinitely divisible; most especially thermodynamics. Stephen Hawking has shown that black hole event horizons have a finite entropy associated with them - but since entropy is a statistical measure of microstates, it follows that the vacuum cannot be continuous on small scales. It must have a discrete structure. Interestingly, this entropy can be computed from aforementioned LQG, which does indeed yield Hawking’s entropy formula.

[Strange]

10 minutes ago, Warped said:

I also agree that the spacetime warp IS gravity. But my point is that it does not involve a "Force" in the classical sense (i.e no force carrying particle is involved, like the hypothsized "graviton" ) therefore gravity CANNOT be quantized 

That is a bit like saying that, classically, electromagnetic waves are continuous and therefore it is impossible to have a quantum theory of electromagnetism. Obviously not true.

A theory of quantum gravity would, necessarily, be different from GR and so the nature of GR cannot be used to preclude a quantum theory. 

Edited July 9, 2018 by Strange

[Warped]

30 minutes ago, Strange said:

A theory of quantum gravity would, necessarily, be different from GR

I'm not sure I understand that. Einstein's theory of gravity is part and parcel of his General Theory of Relativity so how would quantumizing his theory of gravity be different from that which it is a part of in the first place?  

3 hours ago, Silvestru said:

Curvature of space-time not warp.

Several references/discussions regarding gravity use the phrase "caused by the 'warping' of spacetime. Warp = curve

[Markus Hanke]

47 minutes ago, Warped said:

I'm not sure I understand that. Einstein's theory of gravity is part and parcel of his General Theory of Relativity so how would quantumizing his theory of gravity be different from that which it is a part of in the first place?  

Because the process of quantisation leads to a new theory, not just an amendment to the original one (which remains standing within its own domain of applicability). The original theory becomes thus the classical limit of the new quantum one - meaning it is implied by, but not identical to, the quantum version.

[studiot]

43 minutes ago, Warped said:

I'm not sure I understand that. Einstein's theory of gravity is part and parcel of his General Theory of Relativity so how would quantumizing his theory of gravity be different from that which it is a part of in the first place? 

Neither of Einstein's relativity theories are quantum theories.
They rely on purely the mathematics of a continuous variable or variables.

 

When quantum theory first came in it was totally separate and for isntance the Schrodinger equation does not take relativity into account.

Later versions, for instance the Dirac equation, lead to what is known as quantum electrodynamics or QED where SR effects are included.

Particle Physicists then went down another path with QCD (quantum chromodynamics) and further leaving GR to languish.
In honesty the energies involved dwarved the gravitational ones.

No one has yet succeed in the same trick with GR.

You could read the following book by Professor Majid of Mathematics at London university which contains a number of speculative essays on the possible granularity of the universe and spacetime.

 

On Space and Time

Shahn Majid

Cambridge University Press.

[MigL]

A few misconceptions are evident...

Saying gravity is not a force and therefore cannot be quantized, is one.
It is not the force that gets quantized in Quantum Field Theory, but as the name ( and Markus ) suggest, it is the field..
And as AJB once put it; in GR, geometry IS the field.

Secondly, whether space-time is actually curved ( or warped ) is irrelevant.
We have a model, in which the co-ordinate system uses curvature, to effectively describe the paths of objects. And this model, GR, reflects actual paths taken by test masses in reality.
But the fact that the model employs curvature does not mean that space-time necessarily ( or is even able to ) curves ( or warps ). 

[Strange]

3 hours ago, Warped said:

I'm not sure I understand that. Einstein's theory of gravity is part and parcel of his General Theory of Relativity so how would quantumizing his theory of gravity be different from that which it is a part of in the first place?  

QED has almost nothing in common with classical electromagnetism even though, naively, it can be thought of as a quantising of the classical theory. The consequences of quantising are profound, not just an add-on.