What Is Gravity?

[Vmedvil2]

Geodesics.  The routes airlines like to be assigned.  Right?  But airlines use a different word for these routes, don't they?  I cannot recall it.

 

This is Class 7 - where are 1-6?  I see no way to start at the beginning.

 

And, if that enough, who is C Blake - other than, I thini, Australian.

 

Thanks for this.

The Geodesic is the shortest path between two points in a curved space. I don't know who C Blake is he is probably a university teacher.

[hazelm]

The Geodesic is the shortest path between two points in a curved space. I don't know who C Blake is he is probably a university teacher.

Right.  That's why airlines wanted it.  "The shortest distance between two points is a straight line."    Has a curve in it, though, hasn't it?  :-)  

[Farsight]

Just to be clear. Do you see anything wrong with the two links I posted above, other than there simplicity?

No. I wrote them. 

ef Gravity and other theories sucking or inflow etc, starting decades ago we have Quantum inflow. More recently from string theory and quantum mechanics we have Emergent gravity. These were preceded of course by MOND, in an attempt to explain the rotation curves of galaxies without dark matter. Clearly many people think Dark matter is likely a nail in the coffin of GR, mostly because every test to detect it has failed. 

 

Quantum inflow or "the waterfall analogy" is science fiction from people who have never read what Einstein said and don't understand how gravity works. So they come up with an pseudo-explanation that's just lies-to-children. Dark matter isn't the nail in the coffin of GR. Have a read of my Dark matter article and note that in 1916 Einstein said “the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy”. Gravitational field energy, which is spatial energy, causes gravity, and you can't see it.    

 

PS thanks for the heads up on how light speed is measured. However if your clock speeds up and your ruler stretches, at the same time, how are you going to measure a different speed for c.   

By measuring an optical clock going slower than identical optical clock at a higher elevation. There is no time flowing inside either clock. The lower clock goes slower because light goes slower when it's lower.  

 

But a photon travelling at c does not experience time or distance, from its point of view travelling from one side of the universe to here happens instantaneously. 

 

It has no point of view. Imagine if you could travel at the speed of light. Or so close to the speed of light that I can't tell the difference. You'd be subject to a near-infinite time dilation. But it would still take you 8 minutes to travel the 93 million miles that separates the Sun from the Earth, and I could still put an asteriod in your path. BLAM!  

Edited December 30, 2019 by Farsight

[Farsight]

Geodesics.  The routes airlines like to be assigned.  Right?  But airlines use a different word for these routes, don't they?  I cannot recall it.

 

This is Class 7 - where are 1-6?  I see no way to start at the beginning.

 

And, if that enough, who is C Blake - other than, I thini, Australian.

 

Thanks for this.

Light doesn't curves because it "follows a geodesic". That's one of those lies-to-children told by people who don't understand gravity. Imagine you could place a 15 x 15 array of optical clocks throughout a horizontal slice of space around the Earth. Then you plot all the clock rates, such that the lower slower clock rates generate data points lower down in a 3D image, and the higher faster clock rates generate data points higher up in the 3D image. When you join the dots, your plot looks like this:

 

 

It's a plot of the speed of light, and light curves wherever your plot is tilted. It's the gradient that counts. To get the gist of this take a stiff board, lift one side up, and roll a marble across it. The marble follows a curved path because the board is tilted, not because the board is curved:

[Vmedvil2]

 

Light doesn't curves because it "follows a geodesic". That's one of those lies-to-children told by people who don't understand gravity. Imagine you could place a 15 x 15 array of optical clocks throughout a horizontal slice of space around the Earth. Then you plot all the clock rates, such that the lower slower clock rates generate data points lower down in a 3D image, and the higher faster clock rates generate data points higher up in the 3D image. When you join the dots, your plot looks like this:

 

 

It's a plot of the speed of light, and light curves wherever your plot is tilted. It's the gradient that counts. To get the gist of this take a stiff board, lift one side up, and roll a marble across it. The marble follows a curved path because the board is tilted, not because the board is curved:

 

 

This is nonsense, of course the time-space is curved, the speed of light isn't changed. Everything you have said here contradicts General Relativity and Special Relativity. Yes,Yes, everything we know about physics is wrong and your view is correct, oh bullshit..... Look I said it again.

Edited December 30, 2019 by VictorMedvil

[hazelm]

This is nonsense, of course the time-space is curved, the speed of light isn't changed. Everything you have said here contradicts General Relativity and Special Relativity. Yes,Yes, everything we know about physics is wrong and your view is correct, oh bullshit..... Look I said it again.

Seems to me that  light would not - could not - curve.  Give it a wider space  -  even wider space with a curved surface  -   and its rays would simple spread out to fill the space.  Say you cover half a light bulb with a darkening towel.  You get straight rays in all directions except those that would come from the darkened side.  Now pull away the towell and you get more rays - still traveling straight from the bulb on all sides. 

 

What llight does do, though, is fade away over distance.  I believe someone here explained that when my friend asked what happens to light eventually as it travels.  Exchemist, maybe?

[Farsight]

This is nonsense, of course the time-space is curved, the speed of light isn't changed. Everything you have said here contradicts General Relativity and Special Relativity. Yes,Yes, everything we know about physics is wrong and your view is correct, oh bullshit..... Look I said it again.

It isn't nonsense. See what Einstein said:

 

1912: “On the other hand I am of the view that the principle of the constancy of the velocity of light can be maintained only insofar as one restricts oneself to spatio-temporal regions of constant gravitational potential”.

1913: “I arrived at the result that the velocity of light is not to be regarded as independent of the gravitational potential. Thus the principle of the constancy of the velocity of light is incompatible with the equivalence hypothesis”.

1914: “In the case where we drop the postulate of the constancy of the velocity of light, there exists, a priori, no privileged coordinate systems.”

1915: “the writer of these lines is of the opinion that the theory of relativity is still in need of generalization, in the sense that the principle of the constancy of the velocity of light is to be abandoned”.

1916: “In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity”.

1920: “Second, this consequence shows that the law of the constancy of the speed of light no longer holds, according to the general theory of relativity, in spaces that have gravitational fields. As a simple geometric consideration shows, the curvature of light rays occurs only in spaces where the speed of light is spatially variable”.

 

What's nonsense is the idea that light curves because it "follows the curvature of spacetime". Spacetime curvature is associated with the tidal force. It's the second derivative of potential. Gravity is associated with the first derivative of potential. There's no measurable tidal force in the room you're in, so there's no measurable spacetime curvature. But your pencil still falls down. 

Edited December 31, 2019 by Farsight

[Farsight]

GR is a mathematical model published in 1915. It explained the anomalous rotation of mercury, it does not however explain the anomalous rotation of galaxies, without imaginary matter.

It can if you know that “the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy”. And that gravitational field energy, which is spatial energy, causes gravity. Spatial energy causes gravity, the expansion of space is not uniform, and conservation of energy applies.   

 

Tidal forces imply flow, or pressure gradients, which can be described in various ways using different mathematical models. Newtons theories work quite well inside a earth bound room, and can explain using the idea of forces how an apple falls to the ground smacking Newton on the head.

 

The gravitational field is akin to a pressure gradient in space. Don't forget that Einstein talked about the stress-energy tensor, and stress is directional pressure. The idea dates back to Newton:

 

Fair use excerpt from Newton’s views on aether and gravitation by Léon Rosenfeld 1969

  

Do you have a different version of GR in mind? [/size]

 

Yes, the original version. Einstein's version. 

 

I like your explanation on how light speed is always seen to be constant. So why are you arguing its variable? Other than to a distant observer.

 

Because that's what Einstein said, time and time again. 

 

Variable Light Speed theories, (tired light zwicky FTL travel etc) I thought were dead.

 

Tired light is dead. But not the variable speed of light. Most people don't know this because they’ve been taught a version of general relativity that isn’t true to the original, and is wrong.

 

Do you perhaps have a different view on Big Bang cosmology?

 

Not really. I think there was no point singularity, and I think “the cannonball universe” is wrong, but we have good evidence that the universe is expanding.

Edited December 31, 2019 by Farsight

[maheshkhati]

When Einstein create GR only force created by big masses was consider to be gravity but now we  know other forces like additional
gravity (dark matter) & force require for accelerating galaxies away (dark energy).
World is more complicated now & require new thoughts to explain.
I think big mass not only bend the space but create the space as given in my paper in this forum of alternative theory.

Edited January 1, 2020 by maheshkhati

[maheshkhati]

1) Dark matter will be a particle which will not interact with other particle & just floating like dust cloud in space. So, experiment where they consider dark particle will collide & find energy spark will not find it. This must be more stable particle & do not disintegrate. As I consider in last chapter  of my paper.

2) Some scientist try to solve this problem by considering modified gravity concept but as we get some galaxies with no dark matter & other with to much dark matter. 

This become very clear that dark matter is real & present separately than real matter.

[Mutex]

I love these big (and short) questions. 

 

"What is gravity?" good question.

 

All mainstream science can really tell you is what gravity does, it does not address very well (or at all) what it is.

 

Think about Newtonian gravity, Newton goes to great lengths to characterise fairly accurately WHAT gravity does, but really states nothing at all about what it is or how it works (how it does it).

 

Newton just states that it is 'like a force', that appears to be a mass to mass attraction, he makes no claim about what that force is or how that force acts on space separated mass. He just simply states "this is what it looks like" it looks like a force that makes matter interact with matter.

 

So Newton is just describing WHAT it does (again fairly accurately), not how it does it. He does not even attempt to describe the nature of the force, force is a vague term, as is 'gravity'.

 

What gravity is, is an 'effect', we observed the effect of gravity by having weight and by falling down, we know the effect is real (especially when drunk) as we have weight and we fall down.

 

Now it turns out that when you look very closely and precisely at this effect, that Newtons description of it as a force and fitting this his gravity/force equations is incorrect. That does not mean the effect is wrong, just the description of HOW it works differs from actually how it works (the effect).

 

So the Newtonian description of HOW gravity works is the incorrect description (but it was a good call, close, but wrong).

 

Because it was found that Newton's description was wrong led to other scientists to consider how the mechanism (the nature) of gravity works.

Enter Einstein: 

 

Einstein with some limitations (the Newtonian framework) considered that gravity as not a function of matter interacting with matter, but matter interacting with space (and spacetime).

 

Because matter exists in the same space as other matter they both interact with space and space is the common factor (as opposed to mass being the common factor).

 

The typical simple statement about Einstein's relativity is: "Matter tells space how to curve, and space tells matter how to move"

 

So now we should have a simple basis to explain gravity in HOW it works, and not just accurately state THAT it works. (we all know that it works, just not how).

The problem is that even though Einstein's relativity is correct (something about space and time is relative), the problem is that how relativity is derived is from a Newtonian construct. 

 

That is relativity tries to justify Newtonian dynamics that relate to forces and directions (a vector or tensor), as such spacetime is divided up in a Newtonian framework that relates to directions (X,Y,Z dimensions). 

 

So now trying to explain why something falls down or orbits is trying to be explains in a mass/mass relationship that has to do with forces and directions in the context of warped or curved space in the context of forces and directions.

 

The result is non-understanding and confusion and no good description of HOW gravity works.

 

So considering the nature of this problem is sound like science should introduce another layer of complexity, and we can try to explain with Newton with mass/mass/force AND Einstein with Mass / property of space ----- effecting other mass..

 

Lets introduce another complexity and bring in Quantum Mechanics!... Now everything just get ridiculous and crazy.

 

Now I can explain with very minimum math HOW gravity works from first principles, by first principles I mean the observations that confirm that relativity (space is relative in some aspect).

That is by only using what we observe to test that relativity is valid (different rates of time, speed of light being constant, gravitational lensing, Shiparo delay etc).

 

By using those observations and simple math (and first principles) I can show HOW gravity works, we all know that it works just not how it works.

I am really considering writing a post here to start some discussion and debate with smart people.

I take it from another tact, the universe works based on a very simple and small 'instruction set' of rules that work every time, and that are simple, understandable and applied all the time.

 

I have said a lot, but not how gravity works !! But I can give you a simple model that explains what we observe, based on first principles that provides an actual mechanism.

 

So very briefly, this is HOW gravity works (based on the tests that confirm relativity).

 

Matter/mass does not curve or warp space (that is an incorrect assumption of relativity based on it's Newtonian/geometric schema).

Matter/mass goes space a fundermental property of length (space length), so matter does not curve it makes longer as a function of the amount of matter/mass and the distance from that mass.

 

The concept of the space having a simple length property is a bit hard to grasp (it was for me anyway), but once you get that in your head and you just replaced 'curved' with 'length' and 'gravity' with length (of space), it all starts to make sense and begins to explain why things orbit and fall down.

 

You also have to get your head around the fact that the size and length of an object at that particular point in space 'takes on' that space length.

 

Relativity says that the length of 1 second or 1 meter for you is not the same length of 1 meter or 1 second for me (assuming we are in different length space).

But our own 1 second and 1 meter is correct for us. (that's our 'frame of reference').

 

Longer space is lower energy, an amount of energy is lower when that energy is over a larger area and over a longer time.

Matter wants to be in the lowest energy state that is possible, that is the longest space it can get into (and with special relativity, it can get into longer space by going faster in shorter space, using more space over time).

 

Gravity (falling down), is a constant speed into longer space if you are going 10 meters per second, and the length of 1 meter is getting longer in relative terms you are going faster even though you are still going 10 meters per second, if the length of the meter is longer you are going relativity faster (and not experiencing acceleration, you are in free fall).

 

You fall down, because 'below' you (or down)  is longer space and lower energy, you speed up without acceleration because the length of space is increasing. that's how gravity works.. Gravity is just a simple straight line that slopes with a gradient of length of space.

 

I don't know why but I'm pretty obsessed with this subject, I would love to write the book you are asking for.

[hazelm]

I love these big (and short) questions. 

 

"What is gravity?" good question.

 

All mainstream science can really tell you is what gravity does, it does not address very well (or at all) what it is.

 

Think about Newtonian gravity, Newton goes to great lengths to characterise fairly accurately WHAT gravity does, but really states nothing at all about what it is or how it works (how it does it).

 

Newton just states that it is 'like a force', that appears to be a mass to mass attraction, he makes no claim about what that force is or how that force acts on space separated mass. He just simply states "this is what it looks like" it looks like a force that makes matter interact with matter.

 

So Newton is just describing WHAT it does (again fairly accurately), not how it does it. He does not even attempt to describe the nature of the force, force is a vague term, as is 'gravity'.

 

What gravity is, is an 'effect', we observed the effect of gravity by having weight and by falling down, we know the effect is real (especially when drunk) as we have weight and we fall down.

 

Now it turns out that when you look very closely and precisely at this effect, that Newtons description of it as a force and fitting this his gravity/force equations is incorrect. That does not mean the effect is wrong, just the description of HOW it works differs from actually how it works (the effect).

 

So the Newtonian description of HOW gravity works is the incorrect description (but it was a good call, close, but wrong).

 

Because it was found that Newton's description was wrong led to other scientists to consider how the mechanism (the nature) of gravity works.

Enter Einstein: 

 

Einstein with some limitations (the Newtonian framework) considered that gravity as not a function of matter interacting with matter, but matter interacting with space (and spacetime).

 

Because matter exists in the same space as other matter they both interact with space and space is the common factor (as opposed to mass being the common factor).

 

The typical simple statement about Einstein's relativity is: "Matter tells space how to curve, and space tells matter how to move"

 

So now we should have a simple basis to explain gravity in HOW it works, and not just accurately state THAT it works. (we all know that it works, just not how).

The problem is that even though Einstein's relativity is correct (something about space and time is relative), the problem is that how relativity is derived is from a Newtonian construct. 

 

That is relativity tries to justify Newtonian dynamics that relate to forces and directions (a vector or tensor), as such spacetime is divided up in a Newtonian framework that relates to directions (X,Y,Z dimensions). 

 

So now trying to explain why something falls down or orbits is trying to be explains in a mass/mass relationship that has to do with forces and directions in the context of warped or curved space in the context of forces and directions.

 

The result is non-understanding and confusion and no good description of HOW gravity works.

 

So considering the nature of this problem is sound like science should introduce another layer of complexity, and we can try to explain with Newton with mass/mass/force AND Einstein with Mass / property of space ----- effecting other mass..

 

Lets introduce another complexity and bring in Quantum Mechanics!... Now everything just get ridiculous and crazy.

 

Now I can explain with very minimum math HOW gravity works from first principles, by first principles I mean the observations that confirm that relativity (space is relative in some aspect).

That is by only using what we observe to test that relativity is valid (different rates of time, speed of light being constant, gravitational lensing, Shiparo delay etc).

 

By using those observations and simple math (and first principles) I can show HOW gravity works, we all know that it works just not how it works.

I am really considering writing a post here to start some discussion and debate with smart people.

I take it from another tact, the universe works based on a very simple and small 'instruction set' of rules that work every time, and that are simple, understandable and applied all the time.

 

I have said a lot, but not how gravity works !! But I can give you a simple model that explains what we observe, based on first principles that provides an actual mechanism.

 

So very briefly, this is HOW gravity works (based on the tests that confirm relativity).

 

Matter/mass does not curve or warp space (that is an incorrect assumption of relativity based on it's Newtonian/geometric schema).

Matter/mass goes space a fundermental property of length (space length), so matter does not curve it makes longer as a function of the amount of matter/mass and the distance from that mass.

 

The concept of the space having a simple length property is a bit hard to grasp (it was for me anyway), but once you get that in your head and you just replaced 'curved' with 'length' and 'gravity' with length (of space), it all starts to make sense and begins to explain why things orbit and fall down.

 

You also have to get your head around the fact that the size and length of an object at that particular point in space 'takes on' that space length.

 

Relativity says that the length of 1 second or 1 meter for you is not the same length of 1 meter or 1 second for me (assuming we are in different length space).

But our own 1 second and 1 meter is correct for us. (that's our 'frame of reference').

 

Longer space is lower energy, an amount of energy is lower when that energy is over a larger area and over a longer time.

Matter wants to be in the lowest energy state that is possible, that is the longest space it can get into (and with special relativity, it can get into longer space by going faster in shorter space, using more space over time).

 

Gravity (falling down), is a constant speed into longer space if you are going 10 meters per second, and the length of 1 meter is getting longer in relative terms you are going faster even though you are still going 10 meters per second, if the length of the meter is longer you are going relativity faster (and not experiencing acceleration, you are in free fall).

 

You fall down, because 'below' you (or down)  is longer space and lower energy, you speed up without acceleration because the length of space is increasing. that's how gravity works.. Gravity is just a simple straight line that slopes with a gradient of length of space.

 

I don't know why but I'm pretty obsessed with this subject, I would love to write the book you are asking for.

Could it be?  Is gravity an electromagnetic force?

[ralfcis]

Energy is what moves things or forces them apart. Gravity is what slows things down or forces them together. So energy is anti-gravity and gravity is anti-energy. A star's size is a result of the battle between the two. The more energy a star has, the greater its ability to push back against gravity and the less dense and more voluminous it will be.

 

Both energy and gravity have a common enemy in the Pauli exclusion principle which is supported by the other 3 forces: electromagnetic, strong and weak forces. The Pauli principle is what keeps everything separate, it's what keeps you from falling through the floor (it's not electromagnetic repulsion between the outside electrons of the floor and your feet). If you vaporize the floor with enough energy you will fall through it and without the Pauli principle, gravity would have no problem pulling you through the floor. Gravity crushes things and even if it doesn't have to fight against energy, it has a hard time crushing matter because of the Pauli principle (e.g. the transition from neutron star to black hole takes a lot more gravity to overcome the Pauli principle keeping neutrons separate.) (I wonder why there's no such thing as proton or even electron stars.)

 

Despite what Penrose said, black holes are the hardest and coldest things in the universe not only because of their density but also because of their lack of internal movement. The energy and Pauli principle have been crushed out of them. No energy, no movement, not even through time, the field is so dampening of motion. (Victor will come up with his pictures of swirling current within a black hole but the pictures are about as verifiable as pictures of the loch ness monster.)

 

Now everyone believes the other 3 forces exhibit properties of repulsion and attraction; e.g. a proton attracts electrons. Protons can absorb electrons inside a nucleus to become neutrons but if you release that neutron from the binding forces within the atom, it will decay in 15 minutes back into a proton and electron. You'd think once the two come together, the forces of attraction would keep them together. You'd think electrons would just crash into protons of all atoms but they don't. https://wtamu.edu/~cbaird/sq/2013/08/08/why-dont-electrons-in-the-atom-enter-the-nucleus/

 

The other forces keep a distance balance. The strong force is not fighting the electromagnetic repulsion of protons within a nucleus, just as the weak force is not fighting the electromagnetic attraction of an electron to a proton within a neutron. The other 3 forces maintain an eqilibrium over distance which gravity does not so it's really not like the other 3 forces at all. They work with the Pauli principle while gravity works against it.

 

Gravity is confused with inertia which is matter's resistance to be moved by energy. A rocket has inertia yet it takes way more energy to lift it off the earth than to move it in space and once it's moving through space it takes no energy to keep it moving, not so in a gravitational field. So inertia and gravity are not the same thing.

 

Gravity can best be defined by what it's not and what it's the opposite of. It's not inertia and it's the opposite of both energy and the Pauli exclusion principle and motion and the other 3 forces. Then there's General Relativity's definition of gravity being like non-moving acceleration. Of course, this is all just my own theory, not  related to comic book science.

Edited January 19, 2020 by ralfcis

[Dubbelosix]

Could it be? Is gravity an electromagnetic force?

There could be a connection - this was realised early on when scientists started to think of unification.

Edited January 20, 2020 by Dubbelosix

[hazelm]

There could be a connection - this was realised early on when scientists started to think of unification.

Thanks and good morning.

[Mutex]

Could it be?  Is gravity an electromagnetic force?

 

Gravity works 'through' the electromagnetic force, it is not itself an electromagnetic force.

 

When you push something (like a car or something) you force you are applying iis a foce that is transmitted through what you are pushing via the electromagnetic forces. You compress what you are pushing, you are forcing the electrons closer together, it's through the EM forces that the mechanical is applied.

 

Same applies if you are pulling on a rope (pulling the car) from the opposite direction you are pulling the electrons in the matter apart, it's the EM bonds of the matter you are working against.. 

 

So the force of pushing or pulling on an object is by it's nature the electromagnetic forces.

 

Gravity, (if considered a fundamental length of space on a gradient). Is the same thing, because it is a gradient of length in the direction of 'down' the effect is 'pulling' from the bottom (stretching the EM force lengths), and 'pushing' from the top, (compressing the EM force lengths).

 

Gravity is then like someone pushing from above and pulling from below, working on the EM forces, the same as if you were using your hands and pushing and pulling on the object.

 

Of course, if you apply too much force you can break the EM bonds, if you push or pull too hard, or with too much force. 

 

However it does not only apply through the EM forces, if you have a solid mass, even if not electromagnetic in nature, a gradient of length of space would still have to same effect. So a neutron would fall in that gradient of length as a function of it's size and the delta length it exists over..

 

That's why it is much harder to had tall things in gravity, more length is more delta length. 

[Vmedvil2]

Gravity works 'through' the electromagnetic force, it is not itself an electromagnetic force.

 

When you push something (like a car or something) you force you are applying iis a foce that is transmitted through what you are pushing via the electromagnetic forces. You compress what you are pushing, you are forcing the electrons closer together, it's through the EM forces that the mechanical is applied.

 

Same applies if you are pulling on a rope (pulling the car) from the opposite direction you are pulling the electrons in the matter apart, it's the EM bonds of the matter you are working against.. 

 

So the force of pushing or pulling on an object is by it's nature the electromagnetic forces.

 

Gravity, (if considered a fundamental length of space on a gradient). Is the same thing, because it is a gradient of length in the direction of 'down' the effect is 'pulling' from the bottom (stretching the EM force lengths), and 'pushing' from the top, (compressing the EM force lengths).

 

Gravity is then like someone pushing from above and pulling from below, working on the EM forces, the same as if you were using your hands and pushing and pulling on the object.

 

Of course, if you apply too much force you can break the EM bonds, if you push or pull too hard, or with too much force. 

 

However it does not only apply through the EM forces, if you have a solid mass, even if not electromagnetic in nature, a gradient of length of space would still have to same effect. So a neutron would fall in that gradient of length as a function of it's size and the delta length it exists over..

 

That's why it is much harder to had tall things in gravity, more length is more delta length. 

 

But you have to remember there is no unified field theory, gravity is the energy-mass of all the forces not just the electromagnetic, general relativity does not take in account the SNF and WNF, that is why in (http://www.scienceforums.com/topic/36350-reconstructing-the-energy-stress-tensor/) thread the SNF and WNF were added to the Energy Density of T₀₀, which was just the electromagnetic energy density in its original form, these other posts on the forum are not just arbitrary. In reality general relativity is off by a degree because it does not take in account these other forces that have energy-mass into the curvature of gravity, which is probably why it fails so dramatically on the Quantum level when the other forces start to become a "Big Thing". You must remember during Einstein's time Quantum Mechanics was just theory which Einstein thought were wrong or didn't exist yet as pillars of physics, so he didn't incorporate them into his general relativity. Though, Einstein spent the last half of his life trying to incorporate them and failed, he was working on a theory of quantum gravity without any success. I wish I had access to his notes during that time of his life it would make unification much easier I believe.

Edited January 25, 2020 by VictorMedvil