Newton's Mechanics Does Not Require Absolute Space and Time

                                                          Local time. 

Newton expressed in the beginning of his monumental Principia Mathematica (Book I p 81-82) a direct warning to not view measured quantities of space and time as the quantities themselves:

• Wherefore relative quantities are not the quantities themselves, whose names they bear, but those sensible measures of them (either accurate or inaccurate), which are commonly used instead of the measured quantities themselves.
• And if the meaning of words is to vie determined by their use, then by names time, space, place, motion, their measures are properly to be understood; 
• and the expression will be unusual, and purely mathematical, if the measured quantities themselves are meant.
• Upon which account, they do strain the sacred writings, who there interpret  those words for the measured quantities.
• Nor do those less defile the purity of mathematical and philosophical truths, who confound real quantities themselves with their relations and vulgar measures.  

But this is exactly what Einstein did in his Special Theory of Relativity with its measuring apparatus of rigid rods and clocks, which in modern physics has replaced Newton's mechanics as being based on concepts of absolute space and time which cannot be identified and so have no meaning.

But interpreting Newton's concept of space and time as "quantities themselves" as "absolute time and space" is not what Newton had in mind understanding of course very well that position and time are both relative and not absolute.  

What Newton said was that if a clock stops, it does not mean that time itself stops. Nothing strange. 

The period of a pendulum clock scales with the square root of length divided by gravitational strength, and so in particular will run slow at higher altitude. But this does not mean that time stops in a space station with effectively zero gravitation. Normal processes of ageing of a human body continue even in weightless state. 

The caesium atomic clock is the most precise clock use to measure time. The rate of such a clock does not change much with changing environment but a dependence on e.g. temperature can be expected. 

In any case the World outside human influence somehow goes around without the help of Swiss clocks and then with local rates of change geared by local physical conditions somehow expressing the rate of local time itself, which is the time entering into Newton's 2nd Law as a law of local acceleration subject to local force. 

The ruling idea of modern physics is that Newton's inverse square law of gravitation requires instant action at distance, which requires global simultaneity and thus universal absolute time, which is viewed to be absurd, and so Newton's time itself must be replaced by Einstein's relative time. 

But as discussed in recent posts and under the tag New View on Gravitation, it is possible to view Newton's law of gravitation as an expression of local instant action, which only involves local time. 

It is thus possible to return to Newton taking advantage of all the marvellous simplicity and accuracy of Newtonian mechanics, and so not continue clinging to Einstein's relativity theory with all mysteries and difficulties it brings along. 

Newton's warning was directly addressed to coming generations, but it did not reach Einstein who apparently did not read even the introduction to Principia and so was free to question Newton's mechanics on loose grounds, and so be elevated to be the portal figure of modern physics whose wisdom cannot be questioned.  

So what do you say? Was Newton's warning well founded?

More from Principia Book I showing that Newton did not ask for any absolute space and time:

• But because the parts of space cannot be seen, or distinguished from one another by our senses, therefore in their stead we use sensible measures of them. 
• For from the positions and distances of things from any body considered as immovable, we define all places ; and then with respect to such places, we estimate all motions, considering bodies as transferred from some of those places into others. 
• And so, instead of absolute places and motions, we use relative ones; and that without any inconvenience in common affairs; 
• but in philosophical disquisitions, we ought to abstract from our senses, and consider things themselves, distinct from what are only sensible measures of them. 
• For it may be that there is no body really at rest, to which the places and motions of others may be referred.

It is a common tactic in a debate to assign an idea to your opponent, which is not really carried by the opponent, so as to forcefully distance yourself from this idea (straw man argument). This is what modern physicists do when the claim Newton's mechanics requires absolute space and time, and then distance themselves from such a stupid idea.  

  

The World = Differentiation + Integration

The mathematics of the Calculus of Leibniz and Newton allows a description of the World as the result of competing actions between differentiation and integration expressed as the Fundamental Theorem of Calculus as follows in non-technical terms: 

• differentiation followed by integration = no change
• integration followed by differentiation = no change 

thus with differentiation the inverse of integration and vice versa. In other words, the World can be seen as a competition/combination between 

• increasing difference: separation: differentiation as local process: destabilising
• decreasing difference: mixing: integration/summation as global process: stabilising.

In the previous posts we saw that small scale mass density and charge density can be "created" by differentiation seemingly "out of nothing" followed by integration to create large scale order over time. The kinetic energy driving this process comes from concentration of matter with decreasing gravitational potential energy. Details of this process is given in the books listed on the blog including in particular Computational Thermodynamics and The Clock and the Arrow decoding the direction of time, together with Real Quantum Mechanics decoding atom physics.

Calculus describes a World with positive mass and charge of variable sign, generated by the Laplacian differential operator, geared by gravitational force on large scale and arising from integration electrostatic force on small scale.

Creating the Universe by Plucking a String 2

The previous post outlined a possible mechanism to create a large scale Universe $U$ of non-negative mass density $\rho$ from a small scale small amplitude perturbation of a zero gravitational potential with mass density "created" from a gravitational potential $\phi$ by the instant action of the Laplacian differential operator $\Delta$ acting in a Euclidean space with coordinate $x$ according to the assignment   

•  $\rho (x,t)= \Delta\phi (x,t)$ for all $x$ and $t>0$,               (G)

where $t$ is a time coordinate starting at time $0$. The only force in $U$ so far is gravitational force $-\rho\nabla\phi$ which together with Newton's 2nd Law describes the dynamics in $U$, which is large scale.

The physics of $U$ is in a second step expanded with an electric potential $V$ with electric field $E=\nabla V$ as a small scale small amplitude perturbation of a zero electric potential with small scale large scale amplitude electric charge $q$ of variable sign created by an assignment analogous to (G):

• $q(x,t)=\Delta V(x,t)$ for all $x$ and $t>0$,                          (E)                 

with $q=q_++q_-$ split into $q_+\ge 0$ and $q_-\le 0$. A further contribution is given by connecting $E$ to a magnetic field $B$ through Maxwell's equations into electro-magnetics.

The result is a Universe including large scale large amplitude physics of gravitation and small scale large amplitude electro-magnetics created from small amplitude perturbations according to (G) and (E) through the action of $\Delta$, as a Universe created by plucking two strings. 

Note the fundamental difference: 

• Gravitational force is attractive/repulsive between masses of same/opposite sign. 
• Universe of positive mass density separated from Universe of negative mass density. 
• Electric force is repulsive/attractive between charges of same/opposite sign. 
• Gravitational potential large scale.
• Electric potential small scale. Electro-magnetics of light of small/large scale. 
• Laplacian differential operator fundamental as instant local action. 
• No need of instant action at distance.  
• The relative strength of electrostatic and gravitational force between a proton and an electron is nearly $10^{40}$.   

The effect is a toy Universe of large scale non-negative mass density + small scale charge density of variable sign + large/small electro-magnetics of light captured by Newton + Maxwell + Schrödinger as a unified theory. Einstein has no role to play.

Creating the Universe by Plucking a String 1

Under the label New View on Gravitation I have tested the idea of letting gravitational potential $\phi (x,t)$ with $x$ a Euclidean coordinate and $t$ a time coordinate, have a primordial role from which mass density $\rho (x,t)$ is "created" by the Laplacian differential operator $\Delta$:

• $\rho (x,t) = \Delta \phi (x,t)$ for all $x$,         (G1)

assumed to act without time delay for all $t$. Mass is thus created locally for each $x$ by differentiation as an instant local operation acting at each time instant $t$.  

This is to be compared with the standard view that gravitational potential $\phi$  is created from primordial mass density as solution of the differential equation:

• $\Delta\phi (x,t)=\rho (x,t) $ for all $x$,           (G2)

represented by the integral formula

• $\phi (x,t) =-\frac{1}{4\pi}\int\frac{\rho (y,t)}{\vert x-y\vert}dy$

which requires instant action at distance and so represents a main mystery of modern physics.

We recall that the Laplacian is invariant under an orthogonal change of coordinates and so the creation process (G1) is independent of the choice of Euclidean coordinate system, which can be seen as a sign of possible physicality. 

(G1) allows "creation of something big from something small" in the following way: Let us start from a gravitational potential $\Phi =0$ satisfying $\Delta\Phi =0$ thus with corresponding zero mass density. Let $\Phi$ be subject to a small scale small amplitude oscillatory perturbation $\phi$ creating small scale large amplitude oscillatory mass density $\rho =\Delta\phi$ by the action of second order differentiation with $\rho =\rho_++\rho_-$ decomposed into positive mass density $\rho_+$ and negative mass density $\rho_-$.  

The action of gravitational force $-\nabla\phi$ will cause attraction between mass densities of the same sign and repulsion between mass densities of opposite sign, and so will segregate the small scale variation of $\rho$ into one Universe of positive mass and another of negative mass which repel each other and so recede. 

By the action of the Laplacian on a small scale small amplitude oscillating perturbation of a zero state gravitational potential $\Phi =0$, a large scale large amplitude positive Universe $U_+$ with positive mass $\rho_+$ has thus been created, which is balanced by a corresponding negative mass Universe $U_-$ at eventually large distance. 

It is thus possible to envision a scenario where a small perturbation of a zero gravitational potential by the action of differentiation + gravitational attraction/repulsion generates a large scale Universe with positive mass thus representing "creation of something very big from something very small".  

Does this mean that the scenario really starts from zero? Not quite, because starting from $\Phi =0$ satisfying $\Delta\Phi =0$ requires some spatial structure to express the Laplacian. We can see this spatial structure as a string under tension and the small scale small amplitude perturbation as a small amplitude high frequency excitation of the string. 

The creation process thus starts with a spatial structure under tension but without excitation, from which the Universe we are living in is created with "a little pluck of a string".

The scenario opens to the existence of dark matter identified by $\Delta\phi$ of small magnitude but large extension, and dark energy as influence on $U_+$ from $U_-$. 

 

Gravitation: Newton or Einstein?

Modern physics is based on an assumption that Einstein's Theory of Gravitation EG in the form of his General Theory of Relativity gives a more precise description of the true physics of gravitation than Newton's Theory of Gravitation NG. 

Is this assumption justified? What is the evidence that EG is more precise than NG? 

NG based on Newton's 2nd Law and Newton's Law of Gravitation (inverse square law) combines maximal generality with maximal formal theoretical simplicity allowing computational simulation of gravitational interaction of billions of stars/planets over billions of years. 

EG on the other hand comes with maximal theoretical complexity making computational simulation impossible for gravitational interaction already for 3 stars/planets. 

Is it then possible to verify that EG is more precise than NG? If EG is uncomputable? 

The prime evidence that EG is more precise than NG, is a back-of-an-envelope computation by Einstein in 1915 concerning the precession of Mercury showing a correction to a computation by hand using NG made in 1888 by the astronomer Simon Newcomb supposedly taking into account all the effects from the other planets, with the result of 5557 seconds of arc per century (one second of arc=1/3600 degrees). The observed precession was 5600 and Einstein's back-of-an-envelop computation came up with exactly the missing 43 arc seconds per century, which still serves as main evidence that EG is more precise than NG.

How convincing is this? Questions line up:

1. How precise is the computation by hand by Newcomb, supposed to account for all effects in the Solar system with its planets, moons and asteroids swirling around the Sun? Has the number 5557 been confirmed by best possible computation today? If so to what result? Exactly the same as Newcomb?

2. Einstein knew that 43 arc seconds were missing and so could target his correction to fit exactly. Convincing?

3. It is impossible to directly compute the precession by EG. So Einstein starts with the 5557 given by Newcomb using NG for the whole Solar system as a complex many-body system. Einstein then isolates to the two-body problem of Mercury + Sun with EG offering a correction to NG which precisely matches  the missing 43. Magic?

The weakness of Einstein's argument that EG is more precise than NG, is that direct computation with EG to this effect is impossible. It is only possible to start from a NG computation of a complex many-body problem and then isolate to a two-body problem for which EG appears as NG with an extra contribution to potential energy and use this as a correction to the many-body problem. 

It is obvious that this procedure has some weak points. Questions pose themselves:

• Is its worthwhile to spend years of study to come to at least some understanding of EG, when EG is severely uncomputable?
• Is the evidence that EG is more precise than NG convincing?
• Is it reasonable to view EG as a more precise version of NG, when only NG is computable?
• Is it reasonable to use EG as foundation of modern physics when EG is uncomputable?
• Is it reasonable to use EG only as a form of decoration, which serves no practical use?
• Is it reasonable to give up the basic concepts of space and time of Newtonian mechanics, which have served and continue to serve science and society so well?
• Is it a good idea to insist on EG when EG is incompatible with quantum mechanics? 
• Why was EG initially met with very strong skepticism?
• Why was EG accepted only after Einstein's death (and of all his original skeptics)? 

  

Normal Physics from Extreme Physics?

Modern physics is largely based on an idea to find the truth about some physics by subjecting it to extreme tests as if that will bring out the essence. This idea was introduced by Einstein in his famous "thought experiments" of his Special Theory of Relativity SR, with trains being accelerated to speeds comparable to the speed of light, and from such speculations finding revolutionary new truths about space and time today viewed as fundamentals of modern physics. 

To accelerate a 100 ton train to a speed comparable to the speed of light requires more than $10^{20}$ Joule to be compared with the energy of the total yearly production of coal of less than $10^{18}$ Joule. 

This is the idea of of finding the true physics of light by sending single photons (whatever that is) to go through a double split and finding that a photon gets confused about what slit to pass, as the basic experiment of quantum mechanics.

This is the idea in experiments at the LHC at Cern colliding protons at close the speed of light to find out the nature of protons as fundamental building stones of an atoms/molecules together with electrons and neutrons.  

The new ESS in Lund Sweden will smash high speed neutrons into different molecules to find out their essential functioning in a normal environment.. 

This idea is also present in Einstein's General Relativity as a Theory of Gravitation supposed to replace Newton's Theory of Gravitation in extreme conditions like the collision of black holes or the Universe as a whole. 

The idea of finding normal physics from extreme physics may appear strange from classic physics point of view with generality and simplicity as leading principle and not extreme particularity of extreme complication. But it has taken a prominent role in modern physics, maybe because it is now possible to perform extremely complicated experiments concerning extreme physics and finding extremely small effects. 

An example is the proclaimed detecting of exceedingly weak gravitational waves from a collision of two black holes as an event of maximal strength, awarded the Nobel Prize in Physics in 2017. 

Experts of modern physics with (i) relativity theory + (ii) quantum mechanics the essential advancements of classical physics, are eager to reveal the fact that both (i) and (ii) are very difficult to understand. An effect is that there are many conflicting efforts to simplify with little agreement since the formation of the theories 100 years ago, now manifesting itself as a crisis of modern physics.

This is to be compared with classical theories of physics formed to be maximally clear and understandable and so also being supported by a common agreement.

You find on this blog efforts to make atom physics understandable as Real Quantum Mechanics, and macroscopic mechanics as Many-Minds Relativity.

The Role of Einstein's Theory of Gravitation in Modern Physics

The general view presented to the world by the physics community is that modern physics as physics after 1900, as opposed to classical physics before 1900,  is based on 

• Einstein's Special Theory of Relativity SR and General Theory of Relativity SR replacing Newton's Theory of Mechanics NM, together with
• Quantum Mechanics QM for atomic physics as an extension of Maxwell's Theory of Electromagnetism ME and Newton's Mechanics NM to atomic scales.

The completely new aspect of modernity are Einstein contributions to physics offering a completely new insight into basic aspects of space and time with SR presented in 1905 followed by GR in 1916 after an 11 year long hard struggle. 

But the reception by the physics community of Einstein's revelations were met with skeptics or refutation or ignorance, in particular by the Nobel committee for the Physics Prize 1921, which awarded Einstein for explaining the law of photoelectricity but with the explicit mention that his relativity theory was not included in the motivation. This situation changed only after Einstein's death in 1955, but then slowly accelerated to its position today as the fundamental theory of gravitation replacing Newton's Theory of Gravitation NG included in NM, which had served humanity so incredibly well for 300 years. The history is captured in the book Building the General Relativity and Gravitation Community during the Cold War by Roberto Lalli.

Here is a typical reaction to GR (Charles Lane Poor):

• The Relativity Theory, as announced by Einstein, shatters our fundamental ideas in regard to space and time, destroys the basis upon which has been built the entire edifice of modern science, and substitutes a nebulous conception of varying standards and shifting unrealities. 
• And this radical, this destroying theory has been accepted as lightly and as easily as one accepts a correction to the estimated height of a mountain in Asia, or to the source of a river in equatorial Africa.

This is where we stand today: Physics is based on GR for gravitation and QM for atom physics, but the big trouble is that GR and QM are viewed to be incompatible, which is a catastrophe from scientific point of view.

But NG is compatible with QM, and so it is natural to ask if it is really necessary to give up Newton for Einstein? 

A modern physicist will tell you that in fact GR reduces to NG in the case of (i) weak  and (ii) static gravitation, and then admit that this covers almost everything. In fact, what is not included in (i)+(ii) is something extremely speculative, such as collision of black holes, for which the physics is unknown and so the functionality of GR. 

In other words, NG works as well today as ever before, as the most successful mathematical theory all times, and the claim that NG has to be replaced by GR appears to have little factual basis. In fact, GR is so computationally demanding that simulation of even a simple system like the Solar system is unthinkable, while with NG this is captured in a couple of lines of code and executed on a laptop in seconds. 

If NG still works fine, what was the motivation to promote GR after Einstein's death but reject it before?

Was it the result of a stalemate of modern physics in 1960s after the immense success of the atomic bomb at the end WW2? When constructive new ideas are missing, a return to some old ideas may come to rescue.

In any case GR was lifted up from obscurity to top position, but then GR as theory had to be inspected with new eyes and this was far from easy, since GR is so mathematically demanding that it can be grasped by only a few, if any. 

Today this is handled as follows: GR is fundamental and very difficult to understand and apply, but since NG works so fine it is not necessary to dig into the theory of GR in any detail. It is sufficient to know that GR has replaced NG, while NG is used in practice. GR can then be presented as a fundamental step forward as concerns fundamental aspects of space and time as an expression of the power of modern physics. 

The only trouble is that GR is incompatible with QM, and so either GR or QM must be wrong. 

  

Conundrum of Modern Physics

A modern physicist will proudly tell you that modern physics is based on two theories: 

• Einstein's Special Theory of Relltivity SR and General Theory of Relativity GR replacing Newton's Mechanics NM.
• Quantum Mechanics QM replacing Maxwell's Electromagnetics ME and NM on atomic scales.  

Modern physics is based on SR/GR + QM, while classical physics is based on NM + ME. 

A modern physicist will then inform you that SR/GR and QM are the greatest scientific achievements of all time, each with complete agreement with all observations. The only caveat well understood from the start 100 years ago, is that SR/GR and QM are incompatible, which has plunged modern physics into a credibility crisis. Real physics cannot be incompatible/contradictory and so something must be fundamentally wrong with the mathematical models. But what?

QM can be seen as a generalisation of ME and NM to atomic scales and there is no incompatibility here. So it must be SR/GR posing the problem. 

SR without gravitation introduces new relativistic mechanics based on Lorentz transformation mixing space and time into new strange effects of space contraction and time dilation, and so dismisses NM without gravitation, because it is not Lorentz invariant, as an ad hoc requirement.

GR introduces gravitation as a geometric effect of curved space-time and so dismisses NM with gravitation as a classical field theory in Euclidean space. 

NM has thus been replaced by SR (1905) and GR (1916) as a prime achievement of modern physics with very little change into our days, as if the last word was said 100 years ago. 

But NM is the most successful theory of all times encompassing a very large range of phenomena in computable form opening to a very rich world of simulations. In contrast GR is admittedly very difficult to put to work in simulations, because it is so incredibly complicated that even the largest computer and best programmer cannot make it go. The only way to put GR to use is to let it collapse to NM, while GR beyond NM is reserved for speculations on cosmological scales, or bigger.

Newton's theory of gravitation connects gravitational potential $\phi (x)$ to mass density $\rho (x)$ by the Laplacian differential operator $\Delta$ acting in a Euclidean space with coordinate $x$ by 

• $\rho (x)=\Delta\phi$  for all $x$      (NG)

which can be viewed as an assignment creating mass by differentiation of gravitational potential and which can be motivated from conservation principles as shown in this post.  (NG) is the only possible connection between gravitational potential and matter well understood by the Creator.  You find more information on (NG) under tag New View on Gravitation.

Einstein decided to throw out (NG) as the pinnacle of mathematical thinking all times all areas. Einstein replaced (NG) by GR taking the position of Newton under the excuse "Newton, forgive me!" and so was exploited by the physics community to represent all the marvel of modern physics to the world, while his fellow physicists viewed him with pity for missing the train to modernity.

It is now time to reconsider the reasons put forward to replace NG by GR. The cost is very high, while the gains may just be fantasy. 

Galilean-Newtonian Relativity

A common view today is that Newtonian Mechanics requires the notion of absolute space, which however cannot be identified, and so is used to motivate a departure into relativistic mechanics in the form of Einstein's Special Theory of Relativity SR without gravitation and General Theory of Relativity GR with gravitation.

But Newtonian Mechanics is already relativistic in the sense that it takes the same form in all Euclidean coordinate systems moving with constant velocity with respect to each other (so called inertial systems) and so it is impossible by experiment to identify a special system to act as absolute space. This is because both Newton's 2nd Law N2 and Newton's Law of Gravitation NG take the same form in all inertial systems. This was well understood already by Galileo. 

We have seen in posts on New View on Gravitation that NG can according to Laplace be formulated as the local assignment

• $\rho (x)=\Delta\phi (x)$ for all $x$       (NG)  

where $\rho (x)$ is mass density and $\phi (x)$ gravitational potential depending on a Euclidean space variable $x$ and $\Delta$ is the Laplacian differential operator. Viewing (NG) as assignment means that somehow matter is endowed with mass through that action of the Laplacian on the gravitational potential.

Since the Laplacian is invariant under both translation and rotation, it follows that so is NG and thus the generation of mass from gravitational potential does not depend on choice of coordinate system, which is a natural requirement. 

On the other hand, N2 is not invariant under rotation since centripetal forces from acceleration arise. It is thus possible to detect rotation by experiment such as Newton's Bucket. 

Conclusion: Newtonian Mechanics is relativistic in the Galilean sense of taking the same form in all inertial systems, and so does not require the notion of absolute space. Thus there does not seem to be any compelling reason to replace Newtonian Mechanics by SR/GR mechanics. Adding propagation of light to the mechanics picture motivates a modification on celestial scales as shown in Many-Minds Relativity. 

Remark:In Newton's Bucket experiment it can be decided that it is the bucket which rotates vs the fixed stars (and not the other way around) by considering the evolution in time from an initial state with the bucket at rest with respect to the fixed stars. With this point of view a Euclidean coordinate system determined by the fixed stars, may serve as an absolute space, but it is also possible to connect coordinate system to the Sun, Earth, or your living room. 

Gravitational Potential as Primordial without Instant Action at Distance

                                           Gravitation cannot be stopped. Why?

New Newtonian Gravitation explores a view that gravitational potential $\phi (x)$ is primordial as generator of both space with Euclidean coordinate $x$ and matter with density $\rho (x)$ by the assignment

• $\rho (x)=\Delta\phi (x)$ for all $x$ and all time       (NGnew)

as instant-local-action performed by Laplace's differential operator $\Delta$. 

This is to be compared with the standard view with instead matter density primordial and gravitational potential generated as solution to the differential equation

• $\Delta\phi (x)=\rho (x) $ for all $x$ and all time       (NGold)

with gravitational force $-\nabla\phi$ from instant-action-at-distance. (NGold) thus harbours the main unresolved mystery of Newtonian gravitation motivating Einstein's General Theory of Relativity GR supposedly without need of instant-action-at-distance. (NGold) and also GR ask for some form of graviton particle as force carrier, which has not been found, and is not needed in (NGnew). The standard view is that all atoms in the Universe are connected/attracted to each other by exchanging a stream of gravitons as force carriers, which is an absurd idea.  

The reason matter is viewed as primordial as generator of gravitational potential, is of course that matter is visible (except for dark matter) while gravitational potential/force is invisible. 

Replacing (NGold) by (NGnew) replaces unthinkable instant-action-at-distance mediated by gravitons as force carriers, by thinkable instant-local-action and so does not force giving up Newtonian gravitation as the formidable success of mathematical thinking it is. 

(NGnew) with gravitational potential as primordial without gravitons may explain why it is impossible to "stop gravitation" by some form of barrier in the same way as light can be prevented entering your bedroom by pulling the curtains.

It is impossible to prevent local action by setting up some barrier to influence from outside. We can compare with "external enemies" which can be stopped at the border, and "internal enemies" which can show up anywhere and so cannot be stopped. 

(NGnew) gives a rationale why blocking gravitation is impossible.

Summary: (NGnew) is compatible with observations that gravitation cannot be prevented from acting out. There is no space which is free from gravitation. The gravitational potential is everywhere but you cannot see it, only its action on matter like Newton's falling apple. The gravitational potential as primordial can generate both space and matter. There is no vacuum. Space is generated when being filled with gravitational potential generating matter. Is this a new revelation, or already dismissed?

Compare with fancy of Gravity with an On/Off Switch.