### Archives For general relativity

22nd International Conference on General Relativity and Gravitation

I am attending GR22 in Valencia Spain, to present a poster and also take part in the talks. I will be presenting a poster based on this paper (soon to be published) from a talk I gave at DICE2018.

What the paper and poster argue is that in the BMV experiment, observing entanglement is not enough to show that gravity is quantum. I do this by showing that a classical gravitational field coupled to the Bohmian trajectories of the individual particles will show entanglement.

The conference looks like its going to be interesting to attend.

The image at the top shows 4 runs of the BMV experiment, with all 4 Bohmian particle trajectory combinations shown. There is entanglement generated 1/4 of the time, when the experiment happens to look like the 2nd diagram from the left.

The poster is 90 x 200cm, available in real 3D, if you visit Valencia From July 7-12 2019 :-)

The BMV experiment sets out to show that gravity is quantized. If gravity is quantized, we expect to be able to form a gravitational field into a superposition, so that fundamentally the gravitational field is not certain at one spacetime point. Trying to come up with a theory of gravity that can be in a quantum superposition, while still working for all present tests of Einstein’s General Relativity has proved impossible so far, despite thousands of very smart people working over 50 years on the problem.

Perhaps gravity cannot be quantized. With Bohmian trajectory gravity, gravity is not quantized and has a well-defined connection to the sub-atomic particles.

If gravity is not quantized, all sorts of assumptions about quantum mechanics suddenly fail, as an unquantized gravity allows one to cheat behind the back of quantum mechanics. This is a large part of the reason why many people think gravity must be quantized. I’m not in the gravity must be quantized group, mostly because I think it just won’t work.

### as revealed by J.S. Bell and experimental results.

Consider the following facts.

1. The experimental record shows that the Lorentz transformations and special and general relativity all work remarkably well, from galaxies and indeed the structure of the Universe on down to scales probed by CERN.
2. Locality is demonstrated in virtually all experiments conducted to date. This holds across fields such as fluid dynamics, radiation fields, etc. We have local causality.
3. Quantum experiments such as those done by Aspect and later show that not everything is local – we have non-local effects. The wavefunction collapse is instant, etc. This worried Einstein.

Given the above facts, the simplest spacetime I can come up with looks roughly like this:

So this spacetime, which is not new, ( Wheeler had similar ideas), seems to cover our knowledge about the logical structure of quantum mechanics and general relativity. Until someone comes up with something better, this is what I use.

### Causality vs locality vs non-signalling

• Spacetime is locally casual. Einsteins equations show us how things need to touch (with light or gravity waves, etc) in order to interact.
• Locality is therefore local in nature only.
• non-signalling holds today, but there seems to be no reason for it. We have a connection, we just need to figure out how to use it.
• Spacetime is multiply connected, which means it is not globally localized. Events can interact outside of their past light cones.

### Conclusion

This is how our universe operates: we feel everything locally causal. But experiment shows some non-local (in the global sense) connections.

I think that the biggest news in a while in quantum mechanics is newly forming ability of experimenters to do quantum experiments with gravity. A fine example of an experiment already done is Phase Shift in an Atom Interferometer due to Spacetime Curvature across its Wave Function by Asenbaum et al. They conclude:

Therefore, the phase shift of this interferometer is not determined by the local acceleration along a single populated trajectory, demonstrating that the atomic wavefunction is a nonlocal probe of the spacetime manifold [34].

Thus they have experimentally shown that wave functions feel gravity pretty much where they ‘are’ in real space ( try not to think of configuration space at this point! ). No one really doubted this would happen. Still, it leads one to wonder what about the other side – the backreaction – to this. Do the atoms in the Asenbaum experiment source gravity in the same way they detect it? It would seem obvious that they should, but no one has done an experiment to verify this (see later in this article).

A proposal in the opposite spirit to the above results is given by Kafri, Taylor, and Milburn (KTM) in  A classical channel model for gravitational decoherence. KTM posits a way for the gravity to be sourced as follows:

That is, the gravitational centre of mass coordinate,xi, of each particle is continuously measured and a classical stochastic measurement record, Jk(t), carrying this information acts reciprocally as a classical control force on the other mass.

In other words in the KTM model, the source and detection channels for a particle are both as in semi-classical gravity. The expectation value of the particle’s is the mass location for both source and detection.

You can sense that the Asenbaum experiment shows KTM does not work – the experiment shows that atom, which is in a dual humped wave function with a separation of centimeters cannot be seeing only the average field – the wave function senses the curvature.  The paper by Altamirano, Corona-Ugalde,  Mann,  and Zych Gravity is not a Pairwise Local Classical Channel , confirm these feelings about KTM – like theories. They don’t work.

Here we show that single-atom interference experiments achieving large spatial superpositions can rule out a framework where the Newtonian gravitational inter-action is fundamentally classical in the information-theoretic sense: it cannot convey entanglement. Specifically, in this framework gravity acts pairwise between massive particles as classical channels, which effectively induce approximately Newtonian forces between the masses.

So gravity is not truly semi-classical. No surprise to me, or to the quantum gravity workers (LQG, String Theory, etc). What many/most quantum gravity people like to think, however, is that KTM or similar (Diosi – Penrose), Rosenfeld like semi-classical gravity basically exhaust the spectrum of classical gravity theories.

### The BMV Experimental Proposals

The papers describing the BMV experiments by Bose et al.Marletto and Vedral, and Christodoulou and Rovelli.

These proposed experiments are in some ways similar to the Asenbaum experiment described above, but instead of atoms, small particles like micro diamonds are prepared in position-dependent superpositions, and instead of a huge mass of lead, two diamonds are dropped near each other, so they can feel the gravitational effect of the other also in a position superposition diamond. The promise of these experiments is tremendous – if successful they might show that gravity is quantized: Christodoulou and Rovell state

...detecting the [BMV] effect counts as evidence that the gravitational field can be in a superposition of two macroscopically distinct classical fields and since the gravitational field is the geometry of spacetime (measured by rods and clocks), the BMV effect counts as evidence that quantum superposition of different spacetime geometries is possible, can be achieved..

A problem I see in these BMV papers is that they all use the predictions of semi-classical theories (not KTM but semiclassical as a source only) as a classical test case, without much thought to the predictions of other ‘classical’ theories of gravity. The possibilities are many and the experimental consequences are not simple.

### Bohmian Trajectories and General Relativity

There have been some papers over the years touting the usefulness of the Bohmian trajectory viewpoint as a better approximation to classical field – quantum system interaction. Usually, the case for using Bohmian trajectories is one of computational or conceptual efficiency, but as Ward Struve in Semi-classical approximations based on Bohmian mechanics puts it:

Finally, although we regard the Bohmian semi-classical approximation for quantum gravity as an approximation to some deeper quantum theory for gravity, one could also entertain the possibility that it is a fundamental theory on its own. At least, there is presumably as yet no experimental evidence against it.

#### The BMV experiment with Bohmian trajectories

The interpretation of the BMV experiment if one assumes Bohmian trajectories are ‘real’ results in the following conclusions:

• Each run of the experiment has particles in any one of 4 configurations, – the trajectories.
• There is no superposition of gravitational fields – each run has a different gravitational field configuration.
• The resulting experimental statistics show entanglement – even though gravity is classical throughout.

The last point is the most surprising. We look at why an experimenter will see entanglement with Bohmian trajectories.

At the heart of the argument is the fact that while these Bohmian trajectories look very classical, they are actually quantum – more clearly subquantum aspects of (Bohm/de Broglie) quantum theory. So we have a situation where we can get behaviour very similar – ( i.e. showing entanglement ) to quantum gravity for the BMV experiment by using classical gravity coupled to Bohmian trajectories, where there is a superposition of gravitational fields – but only in the boring classical histories of the experiment viewpoint. Since the experimenter has only histories to look at, showing that the gravitational field was in a superposition requires more than merely observing some level of entanglement in the BMV experiment.

This is a paper version of the poster I presented at EmQM17 in London.

Abstract:

Some physicists surmise that gravity lies outside of quantum mechanics. Thus theories like the standard semiclassical theory of quantum to gravity coupling (that of Rosenfeld and Møller) are possible real models of interaction, rather than a mere approximation of a theory of quantum gravity. Unfortunately, semiclassical gravity creates inconsistencies such as superluminal communication. Alternatives by authors such as Diósi, Martin, Penrose, and Wang often use the term ’stochastic’ to set themselves apart from the standard semiclassical theory. These theories couple to fluctuations caused by for instance continuous spontaneous localization, hence the term ’stochastic’. This paper looks at stochastic gravity in the framework of a class of emergent or ontological quantum theories, such as those by Bohm, Cetto, and de Broglie. It is found that much or all of the trouble in connecting gravity with a microscopic system falls away, as Einstein’s general relativity is free to react directly with the microscopic beables. The resulting continuous gravitational wave radiation by atomic and nuclear systems does not, in contrast to Einstein’s speculation, cause catastrophic problems. The small amount of energy exchanged by gravitational waves may have measurable experimental consequences. A very recent experiment by Vinante et al. performed on a small cantilever at mK temperatures shows a surprising non-thermal noise component, the magnitude of which is consistent with the stochastic gravity coupling explored here.

Stochastic Gravity and Ontological Quantum Mechanics

I have made a simple calculator to calculate the flux in watts per square metre of gravitational waves given a frequency and a strain. The idea is to show how easy it would be to hide cosmologically important amounts of energy in high frequency gravitational waves.

If we take values of a strain of 15 orders of magnitude lower than LIGOs sensitivity, and a frequency of the Compton frequency, we get levels of energy flux and density that are very surprising. No one talks about this, though, since HFGWs are ‘known’ not to exist. I posit that we should not assume anything about gravitational waves at this point. Its an obvious place for experimentalists to work in. Are there any experiments that can detect gravitational radiation at millions of watts per square meter and nuclear frequencies? This is something that experiments should decide.

The accepted spectrum of gravitational waves does not include the possibility of high-frequency waves.

Just think about it – there is no way we can tell – there may be billions of watts of gravitational wave energy passing through your body right now. They may be there, waiting for us to find them.

The comments on dark energy and dark matter in the calculator are to be interpreted as follows:

### How can ‘dark matter’ be gravitational wave energy?

Dark Matter is measured as an excess of mass/energy – as it’s presence is determined by gravitational effects on regular matter. In fact- experimentally, dark matter is too tied to matter – one can predict the amount of dark matter in a galaxy or galaxy cluster, etc by simply writing down the total mass distribution of baryons! What we know of dark matter is that it’s weakly coupled to matter and that it’s much denser than the level of dark energy that is spread throughout the universe.

#### A possible scenario:

Dark Matter is gravitational waves associated with matter. Call it DarkGW. It looks like the presence of matter controls the amount of dark matter present and DarkGW interacts very weakly with matter (perhaps not in a linear fashion?), perhaps even violatiing the rules of quantum mechanics – after all there is no quantum theory of gravity yet.

In this scenario, dark energy is the ‘leaking’ of this DarkGW into intergalactic space. Thus there is a source for DE and it does not have to have a transcendental source. Its ‘just’ regular radiation – radiation that does not redshift as the Universe ages, as the redshifted bits are replaced on a continual basis by the DarkGW.

This tells us why the amount of DarkGW is related to the amount of Dark Energy (why are they within a factor of two of each other?). As the DarkGW has leaked out, the Universe has expanded. Once the galaxies start to get cold and far apart (say in 200billion years) – the dark energy would start to redshift, and the Universe would approach a ‘balance point’ universe instead of a runaway expansion as in modern LCDM.

### Something is definitely wrong with dark energy:

Riess says that it could be caused by hypothetical “sterile neutrinos”, interactions with dark matter, or a strengthening over time of dark energy (which accelerates the universe’s expansion).

Sterile Neutrinos are a last ditch effort to keep dark energy as a parameter (Lambda) in Einstein’s equations. Its clear to me that the best answer is that dark energy is getting stronger over time. Dark Energy is on the right side of the Einstein equations, not the left. Lambda was a mistake. Its zero.

#### New Parallaxes of Galactic Cepheids from Spatially Scanning the Hubble Space Telescope: Implications for the Hubble Constant

The problem with dark matter in galaxies is that it’s just too organized. Dark matter seems to correlate too well with matter distributions.

What about a field associated with every nucleon that saturates at some level, called S here. (its saturated near dense matter like here on Earth or in the Milky Way plane, while when protons/neutrons get below a certain density, the field then eventually drops as the density of matter drops.

This solves the cuspy galaxy core problem, it also makes the BTFR (Baryonic Tully Fisher Relation) work, it also seems it would work on the bullet cluster, galactic clusters, etc.

### BTFR – explained

The  Baryonic Tully Fisher Relation is one of the most accurate relations in cosmology. It’s a huge thorn in the side of LCDM cosmology, since dark matter and regular matter are not supposed to be in lockstep with one another. See Stacy McGaugh

THE SMALL SCATTER OF THE BARYONIC TULLY–FISHER RELATION

With the S field presented here, there is a saturable field associated with every nucleon. When nucleons are about a mm apart or less on average, the field is at some standard strength, then as the density lowers more, the S field maintains its density (or slowly loses density) until at some limiting low matter density this saturable field starts to drop. By the point this happens there is ~100x more energy in the saturable field than the baryonic density.

This effect can explain the BTFR as dark matter is present in quantities as a function of baryonic mass in some fashion.

### Bullet Cluster

The bullet cluster poses a problem for MOND like theories – there seems to be excess dark matter causing lensing. So dark matter really exists, it seems. The field solves this nicely. No one thinks that the lensing areas of the Bullet cluster are completely free of matter, it’s just that the dark matter is not located where the bulk of the matter is.

The contours show the density (line of sight) of dark matter, while the X-Ray image in orange – purple shows the colliding dense regular matter.

### Galactic Clusters

Clusters of galaxies would not hold together without about 5 times the mass of the individual galaxies available between the galaxies to hold the galaxies together. See Galaxy clusters prove dark matter’s existence as an intro by  Ethan Siegel .

The mechanism is clear – the intergalactic dust and gas provide the framework to energize a large S field which keeps the cluster gravitationally bound.

### Properties of the S field

The S field is associated with matter and has a limiting high density. At low densities (ie halo galactic densities) the field has a mass of up to about 10 (or 100?) times the mass of a nucleon, per nucleon.

Where does the energy come from? It’s dark energy – just clumped. So S is dark energy. There is always a flow of it running around, and its pulled from dark energy as needed to saturate around matter.

What is the form of the field?

What is the minimum energy density in say GeV/m3  ? Dark Energy has an energy density of about 0.5 GeV/m3 .

The max is determined by the maximum density measured for dark matter which is about 0.5 GeV/cm3 (note the centimeter scale used by astronomers when dealing with matter clouds) see my earlier related post  Is Dark Matter merely Inactive Matter?  so about 1003 or a million times the density of dark energy.

Thus the S field saturates at a density of ~ 5e5 GeV/m3 and is present all around us.

The S field density is then some function of the matter density. It turns out that it’s a cumulative effect from all matter enclosed inside ‘R’.

Stacy S. McGaugh and Federico Lelli

Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxy.

From http://stacks.iop.org/0004-637X/836/i=2/a=152?key=crossref.21cde6b778a1e42d6160598a6ba24e03

Start at Equation 22:

Then use $g_{bar} =\frac{GM_{bar}}{R^2}$ and simplify to

$M_{DM} = \frac{M_{bar}}{e^{\sqrt{\frac{GM_{bar}}{R^2 g_{\dagger}}}} \ - 1}$

Thus the quantity of DM inside a certain radius is wholly dependent on the amount of baryonic matter inside that radius. The S field is a cumulative effect of density of regular baryons.

When I use this on density I get

$\rho_{DM} (< R) = \frac{\rho_{bar}}{e^{\sqrt{\frac{4/3 \pi GR\rho_{bar} }{g_{\dagger}}}} \ - 1}$

This equation states that the density of dark matter depends only on the enclosed average density of baryonic matter.

Calculating the acceleration at R , given a 35kPc distance R, and a density of baryons of 1GeV per cm3 gives $4/3 \pi GR\rho_{bar}$  = 1.2×10-10 m/s2 – ie $g_{\dagger}$ which is the Milgrom acceleration. So that’s the cut where dark matter starts to be apparent, as the denominator starts to take off.

Of course, this density equation has limits on both ends. The dark matter S field has a maximum density of about a GeV per cm3 and once the density goes down to about dark energy levels one no longer calls it dark matter. Don’t forget my density version of the equation requires the average density inside R for the galaxy/gas cloud/cluster.

In my mind this S field is HFGW, but it’s not important what is the nature of the field, vs the mass of the field.

It seems to me that battling it out as MOND vs LCDM is perhaps not the best way to approach the problem as there are obviously more models around that might work. One just has to throw out some part of standard model physics!

Looking at the above more, I’m not convinced that sticking exactly to the MOND formula for mass and density is the way to go with this S field idea. I’m hoping there is a function where the density of DM is only given by the local density of matter, but perhaps that will not work. Perhaps there is something happening where DM depends on the total SUM of all all the matter interior to the radius R.

The Tully-Fisher relation (aka Baryonic TFR) is remarkable. As the diagram below shows, the relationship between Vand the baryonic mass of galaxies is just too finely tuned to be caused by dark matter. Something is up. Vis the stellar orbit velocity in the galactic halo. For more details see the paper by Lelli, McGaugh and Schombert .

MOND (MOdified Newtonian Dynamics) is one explanation for the Tully-Fisher relation. It posits that the force towards the centre of a galaxy at large distances is not simply that of Newton, but is modified with the a0 of  1.2×10-10m/s2 in all galaxies in addition to the usual force predicted by standard Newton or General Relativity’s gravity. LCDM Dark matter is a clumsy explanation for the BTFR, as it needs fine tuning for every galaxy (or every galaxy type) in order to make that straight line be so, well, straight.

There is another way to generate an inward acceleration.

We need a force on each nucleon that changes with how much matter is inside the radius where the particle is. It somehow ‘knows’ the gravitational potential at R, and has a force that depends on that!

What I have so far on this is something to do with dark energy being more concentrated in galaxy cores, so the particle feels this dark energy slope and responds to it.

NOTE: This needs to include a dependence on the enclosed M (ie enclosed Dark Energy inside R).  I call this emission based acceleration ‘Anomalous radial nucleonic radiation’  (ARNR). MOND tells us that particles in the galactic halo can ‘weigh’ the galaxy. They have that information. So there must/might be something like dark energy concentrated in the galaxy and the particles react to this, pushing radiation outward and reacting inward. Note in the galactic core the divergence of the DE is 0 – so no extra force on the particle in the middle of the galaxy.

It might seem strange to have this concerted outward radiation pattern though! Here are some possible explanations for an outward constant radiation by the halo constituents.

• I’m a fan of super high (nuclear and above) frequency gravitational wave (HFGW) emission/absorption in atoms and nuclei. So we might have some sort of stimulated emission from nucleons based on the outward flow of HFGW out of a galaxy.
• Dark Energy has a value of about 1GeV/m3 . If this energy is concentrated by the galactic core, then maybe some the nucleon has a force toward the centre of the galaxy in response to the divergence of the DE field.  (i.e. lower radiation resistance in the outward direction). This Dark Energy may be some new field, (or HFGW).
• Some other mechanism. We don’t have to know the mechanism to predict some consequences.

People don’t generally like the MOND theories because general relativity (GR) in its usual form is so well tested and accurate. LCDM is disliked by many because of the fine-tuning required in order to get everything to match observations.  ‘Anomalous radial nucleonic radiation’  (ARNR) allows GR to exist as is.

### Consequences of ARNR

If nuclei really do radiate continuously, (perhaps in violation of quantum – mechanics) then there will be experimental consequences. These consequences may be largely hidden from earth-based experiments, as the emission would be isotropic and take place in some field (such as gravitational waves)  that is hard to detect with current instruments.

There may be other places where cosmological or galactic cluster observations might note this energy output.

In other posts, I have wondered if dark matter is ‘sleeping regular matter‘ and I still think that it may be a viable option, but it seems like any explanation in terms of dark matter may need to be fine-tuned to match observations.

Also, see:

https://tritonstation.wordpress.com/2016/09/26/the-third-law-of-galactic-rotation/

I’m headed to London for the EmQM 2017 conference Oct 26 – 28 2017, which will I am looking forward to.

I attended in 2015. The event has the byline – the 4th International Symposium about Quantum Mechanics based on a »Deeper Level Theory«. Its mission this year is

Towards Ontology of Quantum Mechanics and the Conscious Agent
David Bohm Centennial Symposium

When I first really understood what quantum mechanics really was – in second-year undergrad at the University of Toronto, I immediately read all sorts of books and papers by and about Bohm’s theories. He made quite a change in my outlook of physics in general. I became convinced in 1985 that quantum mechanics was incomplete and that something along the lines of Bohm’s theory was the way to go. That makes the conference more special for me, and I’m sure many other attendees share the same view.

I am presenting a poster which I’m still polishing that up right now (the abstract at least was well received!). Its based on a paper called ‘Fully Classical Quantum Gravity (see link)‘. I have renamed the poster to Stochastic Gravity and Ontological Quantum Mechanics and rewritten most of it.

The poster describes the results of a paper by Vinante et al. :

Improved noninterferometric test of collapse models using ultracold cantilevers . If the results hold up, they are quite breathtaking as they state:



The finite intercept, clearly visible in the inset of Fig. 3 implies that the data are not compatible with a pure thermal noise behavior, and a nonthermal ex-cess noise is present.

The paper details the careful procedures followed to chase down possible experimental problems. The analysis is carefully thought out. The paper claims the results show a possible signature of Adler’s Continuous Spontaneous Localization (CSL), but to me it seems like if the results hold up that its simply a great puzzle to solve! My take (in line with the ‘Fully Classical Quantum Gravity‘ paper) is that this noise is caused by the continuous emission and/or absorption of gravitational waves at nuclear frequencies.

Gravitational waves are notoriously hard to see, and these high-frequency ones (HFGWs) even more so. Indeed, since gravitational wave power goes with the square of frequency, truly tiny values of the gravitational wave strain ‘h’ (h == 0 in flat space and h < 1) make for large energy fluxes. The LIGO observations saw gravitational waves with $h \sim 10 ^{-2}$ . The formula for the flux of a gravitational wave is:

So LIGO can see gravitational waves with a flux of about $1^{-3} watts/m^2$, while at nuclear frequencies like $10^{15} Hz$, the same formula yields an incredible $10^{19} watts/m^2$ – another way to look at that flux is that it represents 400+ kg! of mass per square meter per second! I propose that results like this suggest that matter itself can be made of nothing but elaborate patterns of gravitational structures. Clearly, high-frequency gravitational structures can hold an incredible amount of energy.

Another way of thinking about this result is that anytime a better telescope is built, or one is built that looks at a new wavelength, field or pattern of signals, those signals are not only discovered, they produce deep new insights about our universe. The fact that HFGWs are hard to detect does not mean that they are not there! Indeed, instead of calculating what the flux of HFGWs might be around us, we should instead admit our ignorance and calculate what we don’t know. Huge amounts of gravitational wave energy could be whipping by everything right now and we would not know a thing about it.

It’s going to be a quick few days in London!

–Tom

So Leonard Susskind publishes a paper on arXiv

# Dear Qubitzers, GR=QM

Which of course is what I have been saying all along. Of course Susskind’s paper is actually ‘of course’ not about QM emerging from GR, which is what I believe, and have good reason to follow up on.

Dear Qubitzers,
GR=QM? Well why not? Some of us already accept ER=EPR [1], so why not follow it to
its logical conclusion? It is said that general relativity and quantum mechanics are separate subjects that don’t fit together comfortably. There is a tension, even a contradiction between them—or so one often hears. I take exception to this view. I think that exactly the opposite is true. It may be too strong to say that gravity and quantum mechanics are exactly the same thing, but those of us who are paying attention, may already sense that the two are inseparable, and that neither makes sense without the other.

The ‘paper’ (perhaps letter is a better name), has made the rounds/  Not Even Wrong,

Instead of that happening, it seems that the field is moving ever forward in a post-modern direction I can’t follow. Tonight the arXiv has something new from Susskind about this, where he argues that one should go beyond “ER=EPR”, to “GR=QM”. While the 2013 paper had very few equations, this one has none at all, and is actually written in the form not of a scientific paper, but of a letter to fellow “Qubitzers”. On some sort of spectrum of precision of statements, with Bourbaki near one end, this paper is way at the other end.

While Woit’s nemesis Lubos Motl,

Susskind also says lots of his usual wrong statements resulting from a deep misunderstanding of quantum mechanics – e.g. that "quantum mechanics is the same as a classical simulation of it". A classical system, a simulation or otherwise, can never be equivalent to a quantum mechanical theory. The former really doesn't obey the uncertainty principle, allows objective facts; the latter requires an observer and is a framework to calculate probabilities of statements that are only meaningful relatively to a chosen observer's observations.

Sabine Hossenfelder put it visually on Twitter:

My take is about the same as these popular bloggers. Don’t really think much of it.

Except the title. QM can, I believe, emerge from Einstein’s General Relativity, in much the same way that Bush and Couder’s bouncing drops can display quantum behaviour.

Its ridiculous that 11 dimensions and sparticles have hundreds of times more study than fundamental emergent phenomena. Emergence is the way to go forward. You don’t need a new force/particle/dimension/brane to make fundamentally new physics from what we already have in electromagnetism and general relativity.

See the search links on the side of this blog for some recent papers in these areas.

I have been reading up on the trans-Planckian problem with the black hole evaporation process. (See the end for an update in March 2018)

##### Here is the problem.

An observer far away from a black hole sees photons of normal infared or radio wave energies coming from a black hole (i.e. << 1eV). If one calculates the energies that these photons should have once they are in the vicinity of the black hole horizon, the energy is becomes high – higher than the Planck energy, exponentially so. Of course if we ride with the photon down to the horizon, the photon blue shifts like mad, going ‘trans-Planckian’ – i.e. having more energy than the Planck energy.

Looked at another way: if a photon starts out at the horizon, then we won’t ever see it as a distant observer. So it needs to start out just above the horizon where the distance from the horizon is given by the Heisenberg uncertainty principle, and propagate to us. The problem is that the energy of these evaporating photons must be enormous at this quantum distance from the horizon – not merely enormous, but exponentially enormous. A proper analysis actually starts the photon off in the formation of the black hole, but the physics is the same.

Adam Helfer puts it well in his paper. Great clear writing and thinking.

#### Trans–Planckian modes, back–reaction, and the Hawking process

Helfer, A. D. (2000). Trans–Planckian modes, back–reaction, and the Hawking process. Retrieved from https://arxiv.org/pdf/gr-qc/0008016.pdf See also See Helfer, A. D. (2005). Quantum Character of Black Holes. Retrieved from https://arxiv.org/pdf/gr-qc/0503053.pdf

My take is simple. After reading Hefler’s paper plus others on the subject, I’m fairly convinced that black holes of astrophysical size (or even down to trillions of tons) do not evaporate.

### The math is good. The physics isn’t

Let’s get things straight here: the math behind Hawking evaporation is good: Hawking’s math for black hole evaporation is not in question.

It should be emphasized that the problems uncovered here are entirely physical, not mathematical. While there are some technical mathematical concerns with details of Hawking’s computation, we do not anticipate any real difficulty in resolving these (cf. Fredenhagen and Haag 1990). The issues are whether the physical assumptions underlying the mathematics are correct, and whether the correct physical lessons are being drawn from the calculations.

Yet Hawking’s prediction of black hole evaporation is one of the great predictions of late 20th century physics.

Whether black holes turn out to radiate or not, it would be hard to overstate the significance of these papers. Hawking had found one of those key physical systems which at once bring vexing foundational issues to a point, are accessible to analytic techniques, and suggest deep connections between disparate areas of physics. (Helfer, A. D. (2003). Do black holes radiate? Retrieved from https://arxiv.org/pdf/gr-qc/0304042.pdf)

So it’s an important concept. In fact it so important that much of not only black hole physics but quantum gravity and cosmology all use or even depend on black hole evaporation. Papers with titles like “Avoiding the Trans-Planckian Problem in Black Hole Physics” abound.

### The trans-Planckian problem is indicative of the state of modern physics.

There are so many theories in physics today that rely on an unreasonable extrapolation of the efficacy of quantum mechanics at energies and scales that are not merely larger than experimental data, but exponentially larger than we have experimental evidence for. Its like that old joke about putting a dollar into a bank account and waiting a million years – even at a few per cent interest your money will be worth more than the planet. A straightforward look at history shows that currency and banks live for hundreds of years – not millions. The same thing happens in physics – you can’t connect two reasonable physical states through an unphysical one and expect it to work.

The trans-Planckian problem is replicated perfectly in inflationary big bang theory.

The trans-Planckian problem seems like a circle the wagons type of situation in physics. Black hole evaporation now has too many careers built on it to be easily torn down.

Torn down:

To emphasize the essential way these high–frequency modes enter, suppose we had initially imposed an ultraviolet cut–off Λ on the in–modes. Then we should have found no Hawking quanta at late times, for the out–modes’ maximum frequency would be ∼ v′(u)Λ, which goes to zero rapidly. (It is worth pointing out that this procedure is within what may be fairly described as text–book quantum field theory: start with a cut–off, do the calculation, and at the very end take the cut–off to infinity. That this results in no Hawking quanta emphasizes the delicacy of the issues. In this sense, the trans–Planckian problem may be thought of as a renormalization–ambiguity problem.)

Some may argue that other researchers have solved the trans-Planckian problem, but its just too simple a problem to get around.

One way around it – which I assume is what many researchers think – is that quantum mechanics is somehow different than every other physical theory ever found, in that it has no UV, IR, no limits at all. In my view that is extremely unlikely. Quantum mechanics has limits, like every other theory.

##### Possible limits of quantum mechanics:
• Zero point: Perhaps there is a UV cut – ( Λ ) . The quantum vacuum cannot create particles of arbitrarily large energies.
• Instant collapse. While its an experimental fact that QM has non-local connections, the actual speed of these connections is only tested to a few times the speed of light.
• Quantum measurement – Schrödinger’s cat is as Schrödinger initially intended it to be seen – as an illustration of the absurdity of QM in macroscopic systems.

If there is a limit on quantum mechanics – that QM is like any other theory – a tool that works very well in some domain of physical problems, then many many pillars of theoretical physics will have to tumble, black hole evaporation being one of them.

### The other argument – Unruh saves evaporation?

March 2018 update: Ok – upon reading this paper by Steven B. Giddings

Where does Hawking radiation originate? A common picture is that it arises from excitations very near or at the horizon, and this viewpoint has supported the “firewall” argument and arguments for a key role for the UV-dependent entanglement entropy in describing the quantum mechanics of black holes. However, closer investigation of both the total emission rate and the stress tensor of Hawking radiation supports the statement that its source is a near-horizon quantum region, or “atmosphere,” whose radial extent is set by the horizon radius scale.

So after I wrote this I am not convinced that holes don’t radiate.

Adam’s argument is below. Basically in order for Unruh’s/Giddings ‘saving’ of black hole radiation to work, there has to be enough ‘source space’ around the black hole to generate the Hawking radiation. There might be.

##### Qingdi Wang, Zhen Zhu, and William G. Unruh

How the huge energy of quantum vacuum gravitates to drive the slow accelerating expansion of the Universe

It (I will call the paper WZU) has been discussed at several places:

Phys.org,

Sabine Hossenfelder at the Backreaction blog,

So why talk about it more here?

Well because its an interesting paper, and I think that many of the most interesting bits have been ignored or misunderstood (I’m talking here about actual physicists not the popular press articles).

For instance here are two paragraphs from Sabine Hossenfelder

Another troublesome feature of their idea is that the scale-factor of the oscillating space-time crosses zero in each cycle so that the space-time volume also goes to zero and the metric structure breaks down. I have no idea what that even means. I’d be willing to ignore this issue if the rest was working fine, but seeing that it doesn’t, it just adds to my misgivings.


So with the first paragraph, Sabine is talking about the a(t, x) factor in the metric (see equation 23 in the paper). I think that she could be a little more up front here: a(t, x) goes to zero alright, but only in very small regions of space for very short times (I’ll come back to that later). So in reality the average of the a(t,x) over any distance/time Planck scale or larger determines an almost flat, almost Lambda free universe -> average(a(t,x)) –> the a(t) as per a FLRW metric. I guess Sabine is worried about those instants when there are singularities in the solution. I agree with the answer to this supplied in the paper:

It is natural for a harmonic os- cillator to pass its equilibrium point a(t,x) = 0 at maximum speed without stopping. So in our solution, the singularity immediately disappears after it forms and the spacetime continues to evolve without stopping. Singularities just serve as the turning points at which the space switches.

...(technical argument which is not all that complicated)...

In this sense, we argue that our spacetime with singularities due to the metric becoming degenerate (a = 0) is a legitimate solution of GR.

As I said, more on that below when we get to my take on this paper.

The second paragraph above from the Backreaction blog concerns the fact that the paper authors used semi classical gravity to derive this result.

The other major problem with their approach is that the limit they work in doesn’t make sense to begin with. They are using classical gravity coupled to the expectation values of the quantum field theory, a mixture known as ‘semi-classical gravity’ in which gravity is not quantized. This approximation, however, is known to break down when the fluctuations in the energy-momentum tensor get large compared to its absolute value, which is the very case they study.

They are NOT using a classical gravity coupled to the expectation values of the quantum field theory. Indeed, according to WZU and the mathematics of the paper they say:

In this paper, we are not trying to quantize gravity. Instead, we are still keeping the spacetime metric a(t, x) as classical, but quantizing the fields propagating on it. The key difference from the usual semiclassical gravity is that we go one more step—instead of assuming the semiclassical Einstein equation, where the curvature of the spacetime is sourced by the expectation value of the quantum field stress energy tensor, we also take the huge fluctuations of the stress energy tensor into account. In our method, the sources of gravity are stochastic classical fields whose stochastic properties are determined by their quantum fluctuations.

So I think that she has it wrong. In her reply to my comment on here blog she states that its still semiclassical gravity as they use the expectation values of the fluctuations (they don’t as you can see by the quote above or better by looking at the paper. See how the equation 29 talks about expectation values, but the actual solution does not use them ). She concludes her comment: “Either way you put it, gravity isn’t quantized.” I think that’s also fair appraisal of  the attitude of many people on reading this paper many people don’t like it because gravity is treated classically.

## Why I think the paper is interesting.

#### Gravity is not quantized: get over it

I think its interesting as their approach to connecting gravity to the quantum world is basically identical to my Fully Classical Quantum Gravity experimental proposal – namely that gravity is not quantized at all and that gravity couples directly to the sub-quantum fluctuations. Wang and co-authors apologize for the lack of a quantum theory of gravity, but that appears to me anyway as more of a consensus-towing statement than physics. Indeed, the way its shoved in at the start of section C seems like it is an afterthought.

#### (Gravitational) Singularities are no big deal

Singularities are predicted by many or (even all?) field theories in physics. In QED the technique of renormalization works to remove singularities (which are the same as infinities). In the rest of modern QFT singularities are only perhaps removed by renormalization. In other words quantum field theory blows up all by itself, without any help from other theories. Its naturally bad.

The Einstein equations have a different behaviour under singular conditions. They are completely well behaved. Its only when other fields are brought in, such as electromagnetism or quantum field theory that trouble starts. But all on their own singularities are no big deal in gravity.

So I don’t worry about the microscopic, extremely short lived singularities in WZU at all.

#### Why it’s exciting

We have WZU metric equation 23

ds2 = −dt2 +a2(t,x)(dx2 +dy2 +dz2)

a(t,x) oscillates THROUGH zero to negative, but the metric depend on a^2, so we have a positive definite metric that has some zeros. These zeros are spread out quasi periodically in space and time. If one takes two points on the manifold (Alice and Bob denoted A & B), then the distance between A and B will be equivalent to the flat space measure (I am not looking at the A and B being cosmic scale distances apart in time or space, so its almost Minkowski). Thus imagine A and B being 1 thousand km apart. The scale factor a(t, x) averages to 1.

Here is the exciting bit. While an arbitrary line (or the average of an ensemble of routes) from A -> B is measured as a thousand km, there are shorter routes through the metric. Much shorter routes. How short? Perhaps arbitrarily short. It may be that there is a vanishingly small set of paths with length ds = 0, and some number of paths with ds just greater than 0, all the way up to ‘slow paths’ that spend more time in a > 1 areas.

Imagine a thread like singularity (like a cosmic string – or better a singularity not unlike a Kerr singularity where a >> m). In general relativity such a thread is of thickness 0, and the ergo region around it also tends to zero volume. One calculation of the tension on such a gravitational singularity ‘thread’ (I use the term thread as to not get confused with string theory) come out to a value of about 0.1 Newtons. A Newton of tension on something so thin is incredible. Such a thread immersed in the WZU background will find shorter paths – paths that spend more time in areas where a << 1, these paths being much more energetically favoured. There are also very interesting effects when such gravitational thread singularities are dragged through the WZU background. I think that this might be the mechanism that creates enough action to generate electromagnetism from pure general relativity only.

A 2D slice at some time through ordinary WZU vacuum. The spots are places where a~2. The straight line from A to B has an average scale factor a of 1, while the wiggly path follows a ~ 0 and hence has an average scale factor of << 1. Note that these short paths are not unique, and there is little constraint for them to be even approximately straight.

So these thread singularities thread their way through the frothy WZU metric and as such the distance a single such thread may measure between Alice and Bob may be far far less than the flat space equivalent.

It seems to me that one could integrate the metric as given in WZU equation 23 with a shortest path condition and come up with something. Here is one possible numerical way: start out with a straight thread from A to B. Then relax the straight line constraint, assign a tension to the thread, and see what the length of the thread after a few thousand iterations, where at each iteration, each segment allows itself to move toward a lower energy state (i.e. thread contraction).

This opens up:

##### Quantum non-locality

Realist, local quantum mechanics is usually thought of requiring  on having some dependency on non-local connections, as quantum experiments have shown. This shortcut path may be an answer to the need for non-local connections between particles, i.e. a mechanism for entaglement, a mechanism for Einstein’s “spooky action at a distance”.

##### Faster than light communication.

Its always fun to see if there are realistic methods where one might beat the speed limit on light. It seems that worm hole traversal has been one of the favourites to date. I think that the WZU paper points at another mechanism – the fact that there exist shorter paths through the sub-quantum general relativistic froth of WZU. How might one construct a radio to do this? Entangled particles, particles that follow the zeros of a(t, x) preferentially, etc etc. One could imagine a brute force method to test this where huge pulses of energy are transmitted through space at random intervals. Perhaps a precursor signal could be measured at the detector, where some of the energy takes a short path through the WZU metric.

Emergent quantum mechanics comes in many forms: stochastic electrodynamics ( Ana María Cetto) , de Broglie – Bohmian mechanics (John W M Bush) , thermal models ( Gerhard Groessing ) etc. In many of these forms of emergent quantum mechanics, particles have a physical existence and experience sub quantal movement. The paper I have just posted looks at the gravitational consequences of this sub quantal motion. An interesting finding is that while a classical Bohr hydrogen atom has a lifetime of about 10^-11 seconds, it would take that same atom 10^40 seconds or so to radiate away a few eV of energy. This indicates that the stability of the atoms is not an indication that gravity needs to be quantized, which is antithetical to Einstein in 1916:
• “…Nevertheless, due to the inner-atomic movement of electrons, atoms would have to radiate not only electro-magnetic but also gravitational energy, if only in tiny amounts. As this is hardly true in Nature, it appears that quantum theory would have to modify not only Maxwellian electrodynamics, but also the new theory of gravitation.” – Einstein, 1916
Einstein it would seem was wrong on the gravtitational side of this.
The paper looks at possible ways to see these tiny emissions (nuclear scale emissions are higher) and thus lays out a quantum gravity experiment achievable with today’s technology.

The experimental parameter space. Most important thing to note is that this is a quantum gravity experiment with an achievable parameter space!

Here is the paper…

Also see these references…

In this two page paper, I look at how the relationship between the dimensions of a Kerr singularity and the strength of the electric Coulomb effect compare.

and try to find your friend at the other end.” — Leonard Susskind

In this talk Leonard Susskind gives a convincing argument as to why he thinks that ER == EPR , where ER denotes an Einstein – Rosen Bridge (aka wormhole) and EPR is the Einstein Podolsky Rosen paper (essentially entanglement).

Leonard draws three entangled pairs of particles on the chalkboard, (image its not merely 3 by 3e40) and then collapse the left and right down to black holes, then the entaglement must continue, and thus ER == EPR

Take a ring of rotating matter.

No matter what frequency it rotates at, there is no General Relativistic waves emanating from it.

Now assume that the matter starts to clump up into two balls. NOW we have GR radiation.

Now run the camera in reverse.

What we have is an object that aggressively reflects (exchanges) GR radiation with other similar objects at the same frequency.

The rings I am talking about are the mass of an electron and very very small.

Take a run of the mill graviton detector: (Not yet built, nor would they be easy to build!).

Put it on a table top, on this planet. Say its detecting 1,000 gravitons per second. Now pull the table out – quickly but smoothly. How may gravitons will it see on its 0.5 second trip to the floor?

The answer is none. Or about 500, or ‘don’t ask’.

According to the equivalence principle: When it drops off the shelf, it is supposed to stop seeing gravitons.

According to QFT – the device is still in a gravitational field, so it will see about 500 gravitons on its half second journey. Note that the speed of the detector has not changed appreciably when it first starts to fall. “All experimental quantities are unchanged”.

This simple thought experiment lies at the

Thoughts:

Turbulence in GR is linear and hence does not give rise to cumulative gravitational effects. Indeed, the power that can be transmitted using GR as a factor of the ‘gravity caused’ is immense. For instance: at the power transfer of energy at the Schwinger limit (here I assume 3×1029 watts/m2), the non linear effect – the gravity term is very low.

Say (see http://arxiv.org/pdf/1007.4306v3.pdf) 3×1029 watts/m2 (at optical freq).\

Consider a 1 metre3 box with perfect mirrors at the schwinger limit – how much does that much radiation weigh?

I get 1×1021 Joules per cubic metre at any one time, so that’s 11.1 tonnes. (http://www.wolframalpha.com/input/?i=10%5E21Joules%2F%28c%5E2%29)

That seems like a lot of mass, but 11 tonnes in a cubic metre is not going to alter the static gravitational field much even in the low field limit like that of the earth.

That 11 tonne figure is interesting, as it is also the density of lead. Its strange (or not) that the Schwinger limit is also the density of normal matter.

From the book I am reading now: ( Fields of Color: The theory that escaped Einstein  — Rodney A. Brooks)

“… spin is an abstract mathematical concept that is related to the number of field components and how they change when viewed at from different angles. The more field components, the higher the spin.” 0  ,  1/2  ,  1  , 2  are the spin values so gravity has more field components. Can we mimic a field with a lower number of field components with one that has more field components? Yes. So we generate everything from gravity.

Einstein was of course worried about the electromagnetic radiation emitted from a classical Bohr atom. But I have also learned that he was worried about the GR radiation from that same atom that he claimed was ‘not observed’. I think that the waves would be of very low energy but I should work that out. (re – replenishment from the turbulent gravity).

Random Q: Were there about 5 times TOO MANY GALAXIES in the early universe – which would jive with my thought that dark matter is matter gone dark. In the early Universe matter was packed too tightly for there to be any dark stuff, so there was more galaxy formation. A: Possibly see for instance – http://astronomynow.com/2015/11/21/hubble-survey-reveals-early-galaxies-were-more-efficient-at-making-stars/

Random Q: Frame dragging. Would any other physics change over one of Tamjar’s rotating superconductors where he sees anomalous gravitational effects – i.e. look at decay rates of common isotopes, etc.

Random Q: There is the experiment in Italy where they see decay rates changing as the year advances, which is anomalous. Wonder if some frame dragging can take care of that.

### Can a sub-quantum medium be provided by General Relativity?

Thomas C Andersen, PhD
As a personal note of celebration, Art McDonald, the director of the Sudbury Neutrino Observatory has won the Nobel Prize in Physics. I worked on SNO for 8 years for my masters and PhD. The Sudbury Neutrino Observatory also shared the Breakthrough prize in Fundamental Physics! The breakthrough prize is awarded to the whole collaboration (26o or so of us). It was a real treat to work on the neutrino observatory.
In PDF as a paper, or in as a poster I presented at EmQM15 in Vienna, published in IOP physics. http://iopscience.iop.org/article/10.1088/1742-6596/701/1/012023

tom@palmerandersen.com, Ontario, Canada. (Dated: October 19, 2015)

Emergent Quantum Mechanics (EmQM) seeks to construct quantum mechanical theory and behaviour from classical underpinnings. In some formulations of EmQM a bouncer- walker system is used to describe particle behaviour, known as sub-quantum mechanics. This paper explores the possibility that the field of classical general relativity (GR) could supply a sub-quantum medium for these sub-quantum mechanics. Firstly, I present arguments which show that GR satisfies many of the a priori requirements for a sub-quantum medium. Secondly, some potential obstacles to using GR as the underlying field are noted, for example field strength (isn’t gravity a very weak force?) and spin 2. Thirdly, the ability of dynamical exchange processes to create very strong effective fields is demonstrated through the use of a simple particle model, which solves many of the issues raised in the second section. I conclude that there appears to be enough evidence to pursue this direction of study further, particularly as this line of research also has the possibility to help unify quantum mechanics and general relativity.

### The Sub-quantum Medium

In emergent QM the sub-quantum medium is the field out of which quantum behaviour emerges. Most, if not all EmQM theories published to date do not explicitly define the nature of the sub- quantum medium, instead quite reasonably they only assume that some underlying field exists, having some minimum set of required properties, for instance some sort of zero point field interac- tion.

There have of course been investigations into the physical make up of a sub-quantum medium. Perhaps the most investigated possible source is stochastic electrodynamics (SED)[5]. Investigated on and off since the 1960s, SED posits the existence of a noisy isotropic classical radiation field as the zero point field (ZPF). stochastic electrodynamics as a sub-quantum media has many desirable properties. As an example of progress in stochastic electrodynamics Nieuwenhuizen and Liska[12] have recently used computer simulation techniques to build an almost stable hydrogen atom.

Yet classical electrodynamics has a few problems as the sub-quantum medium. Davidson points out that

”A particle in SED gains or loses energy due to interaction with the zero point field. Atoms tend to spontaneously ionize in SED as a consequence. … The spectral absorp- tion and emission lines are too broad in simple calculations published so far to come anywhere close to fitting the myriad of atomic spectral data.”[4].

Other sub-quantum medium proposals include Brady’s compressible inviscid fluid – an entirely new classical field that is posited to underpin quantum mechanics and electromagnetism.[1]

This paper proposes a sub-quantum medium that is already experimentally confirmed and is somewhat surprisingly stronger and more flexible than usually thought – general relativity (GR). Using GR as the sub-quantum medium as presented here assumes only classical GR. Other pro- posals that are similar in some ways are Wheeler’s geons of 1957 – constructed of source free electromagnetic fields and gravity under the laws of standard QM[11] and Hadley’s 4-geons[8]. Hadley’s proposal is perhaps the most similar to that here, but Hadley assumes the independent reality of an electromagnetic field. This paper instead uses only GR as the fundamental field.

General relativity has some qualities that lend itself to consideration as a sub-quantum medium:

1. Frictionless (inviscid):

The movement of objects through empty space is observed to be frictionless, as waves and objects can travel long distances without measurable hindrance. GR’s ether (such that it is) behaves as an inviscid media in its linear regime, allowing for this. Importantly, there is friction in situations such as Kerr hole frame dragging.

2. Covariant: Manifestly so.

3. Non Linear:

This non – linearity allows for a rich variety of behaviour at small scales – a minimally explored, flexible platform to construct particles.

4. Coupling:
General relativity couples to all material, uncharged or charged.

#### Potential Problems

How can general relativity form a basis for quantum mechanics, given the following: 1. Gravity is weak.

GR is often thought of as a weak force, after all the electromagnetic force between two electrons is some 1042 times that of their gravitational attraction! But for the purposes of a sub-quantum media we are interested in large energy transfers (e.g. Grssing’s[7] thermal ZPE environment), not the weak effects of gravitational at- traction. Instead of 0Hz attraction effects, consider gravitational waves. Looking at optical frequencies (1014Hz), for GR the maximum energy transfer rate be- fore non linear effects start to dominate is tremendously high – about 1065<sup>W/m2. Compare that to electromagnetism, where we have to appeal to something like the Schwinger limit which is only 1030W/m2. Thus GR has plenty of room to host strong effects.

2. Gravity has a weak coupling.

In order to model a quantum system (say a hydrogen atom), we require the quantum forces to be much stronger than the electromagnetic forces. Yet the coupling of gravity to the electron is much weaker than even the electromagnetic force. The solution to this problem lies in realizing that gravity can couple not only through ’0Hz’ effects but also through the exchange of wave energy. The Possible Mechanisms section below outlines how this could happen.

3. Gravity is quadrupole (spin 2).

If we are to also generate EM from GR, we require a spin 1 field to emerge. Emergence is the key – underlying fields can give rise to apparent net fields of different spin. E.g. Monopole gravitational waves[9].

4. Bell’s theorem and hidden variables.

Using GR as the underlying medium to emerge quantum mechanics from would seem to have to satisfy Bell’s inequalities – and thus disagree with current QM theory. Maldacena and Susskind’s EP = EPR paper[10] is an example of a solution to this.

#### Possible Mechanisms

Here I investigate some consequences of purely classical geometric particle models that are the mass of the electron in a universe where the only field is classical general relativity. The exact micro structure of a particle is not of concern here, instead I look at some tools and building blocks with which to build elementary particles from nothing more than classical GR.

An electron like particle is modelled as a small region of space which has some geometric microstructure that results in a particle with the correct mass and spin. I will point out here that a Kerr solution with the mass and spin of an electron happens to have a (naked) singularity at virtually the Compton radius (1/13 the Compton wavelength).

Whatever the exact microstructure of an elementary particle, there is certainly extensive frame dragging occurring. Frame dragging is the ’handle’ to which gravitational wave energy exchange can grip. As Brito et al. start their comprehensive ’Superradiance’ paper:

”Superradiance is a radiation enhancement process that involves dissipative systems”[3].

Superradiance in GR was introduced by Press and Teukolsky’s 1972 paper Floating Orbits, Super- radiant Scattering and the Black-hole Bomb[13].

This paper posits that EmQM’s sub-quantum ZPF might be a run away superradiance effect (limited by non linear mechanics). Is the universe a black hole bomb?

This superradiant (and highly absorbing – see figure 1) energy exchange of the particle with its surroundings causes the particle to be subjected to huge forces – superradiance for example allows for a substantial fraction of the mass of a rotating black hole to change over time scales a few times the light travel time across the of the hole. The recent paper by East et al. studies black holes undergoing superradiance using a numerical method.[6]. It seems that the superradiance is on a knife edge with absorption – these effects happen at only slightly different frequencies.

While the time scale for a black hole with the mass of an electron is a tiny 10−65s, it seems reasonable to assume that the frequency for superradiance is tied to the distance scales involved in the particles structure, so there could be superradiant effects happing on different timescales. For instance, an effect at 10−65s could be holding the particle together, while the forces of EM and the actions of QM might take place using waves closer to the electron Compton frequency.

Look now at a Compton frequency superradiant process. We have an energy exchange of some fraction of the mass of the electron happening at 1.2×1020Hz. The maximum force an effect like this can produce on an electron mass particle is of order 0.01 Newtons! Forces like this are surely strong enough to control the movement of the electron and phase lock it, giving rise to the sub-quantum force.

#### FIG. 1: From East[6]: Top: mass change over time, for incident gravitational waves with three different frequencies. ω0M = 0.75 is superradiant, while ω0M = 1 shows complete absorption. Bottom – shows the effect of the wave on the shape of the horizon – so the entire wave packet can be visualized.

There is also a mechanism by which electromagnetic effects can emerge from such energy ex- change. See Brady[2] section 4 for one simple method of calculating an electromagnetic force from mass exchange.

### Discussion

The sub-quantum medium, whatever it is, has to behave so that quantum mechanics can arise from it. I hope that this paper has shown that General relativity covers at least some of the requirements for a sub-quantum medium. In order to fully test this idea, there might likely need to be an actual geometrical model of the electron found. The techniques of numerical general relativity could be the best tool to study these interactions in detail.

If the pursuit of an emergent quantum mechanics is to prove fruitful, then the idea that a field like general relativity does not hold on the microscale may have to be re-considered, as with EmQM there is no overarching ’quantum regime’. With general relativity still on the stage at 10−17m, Occam’s razor perhaps suggests that we prove that general relativity is not the sub-quantum medium before a new field is invented.

1. [1]  Robert Brady. The irrotational motion of a compressible inviscid fluid. page 8, jan 2013.
2. [2]  Robert Brady and Ross Anderson. Why bouncing droplets are a pretty good model of quantummechanics. jan 2014.
3. [3]  Richard Brito, Vitor Cardoso, and Paolo Pani. Superradiance, volume 906 of Lecture Notes in Physics.Springer International Publishing, Cham, jan 2015.
4. [4]  Mark P. Davidson. Stochastic Models of Quantum Mechanics A Perspective. In AIP ConferenceProceedings, volume 889, pages 106–119. AIP, oct 2007.
5. [5]  L. de la Pena and A. M. Cetto. Contribution from stochastic electrodynamics to the understanding ofquantum mechanics. page 34, jan 2005.
6. [6]  William E. East, Fethi M. Ramazanolu, and Frans Pretorius. Black hole superradiance in dynamicalspacetime. Physical Review D, 89(6):061503, mar 2014.
7. [7]  G. Gr ̈ossing, S. Fussy, J. Mesa Pascasio, and H. Schwabl. Implications of a deeper level explanation ofthe deBroglieBohm version of quantum mechanics. Quantum Studies: Mathematics and Foundations,2(1):133–140, feb 2015.
8. [8]  Mark J. Hadley. A gravitational explanation for quantum theory non-time-orientable manifolds. InAIP Conference Proceedings, volume 905, pages 146–152. AIP, mar 2007.
9. [9]  M. Kutschera. Monopole gravitational waves from relativistic fireballs driving gamma-ray bursts.Monthly Notices of the Royal Astronomical Society, 345(1):L1–L5, oct 2003.
10. [10]  J. Maldacena and L. Susskind. Cool horizons for entangled black holes. Fortschritte der Physik,61(9):781–811, sep 2013.
11. [11]  CharlesWMisnerandJohnAWheeler.Classicalphysicsasgeometry.AnnalsofPhysics,2(6):525–603,dec 1957.
12. [12]  TheoM.NieuwenhuizenandMatthewT.P.Liska.SimulationofthehydrogengroundstateinStochasticElectrodynamics. page 20, feb 2015.
13. [13]  WILLIAM H. PRESS and SAUL A. TEUKOLSKY. Floating Orbits, Superradiant Scattering and theBlack-hole Bomb. Nature, 238(5361):211–212, jul 1972.

I have been thinking about frame dragging and faster than light travel for a few days, and then about the fact that quantum collapse seems to take place ‘instantly’ (faster than light).

So then I read about the photon size for a 1MHz radio wave which is 300 metres – quite large.

So this huge wave has to refract as a wave and yet somehow instantly collapse into a very small area to be absorbed? Instantly? Insanity!

Wild thought: Frame dragging faster than light and gravitational shock waves to the rescue!

Answer: Collapse is a shockwave that causes frame dragging, allowing for ‘instant’ effects to happen (also EPR).

Frame dragging can in principle be used to travel faster than the speed of light. This is a known scientific fact that is thought to be non possible in practice due to all sorts of limitations. Science fiction of course loves it.

So a soliton forms and sweeps energy out of the wave and into the reception antenna.

If we could control this soliton collapse – we could perhaps harness it to perform faster than light communication and travel.

The soliton ‘shock wave’ is composed of gravity (as is light and everything else). It would have to have some very specific configuration.

Frame Dragging

Frame dragging occurs with linear effects too. My thought experiment on this is through a Mach – like view point. If you are inside at the middle of a very long pipe, which starts to accelerate, you will be dragged along. If the pipe stops at some velocity, you will approach that velocity eventually.

So space couples not to mass but to matter. If it just coupled to mass, you would not be able to tell if your neutron rope was moving or not. It couples instead to the actual bits of matter.

What about circularly polarized gravitational waves – timed so that the squished part is always in front and the expansion is behind the particle? So that’s 90 degrees from direction of travel of the waves – but perhaps they can be entrained as a soliton solution. Soliton

Would there be any consequences that we could measure?

http://physics.stackexchange.com/questions/178545/maximum-power-transmitted-using-general-relativity-waves-cf-schwinger-limit

For instance, there is an upper bound of the amount of EM energy that can be poured through a square mm of area – not predicted by Maxwell’s Eqn’s of course, as they are linear, but by quantum field effects. If we instead look at how gravitational energy we can pass through that same square mm, is it the same number of joules/sec? http://en.wikipedia.org/wiki/Schwinger_limit

Well there are a few problems with the Schwinger limit too:

"A single plane wave is insufficient to cause nonlinear effects, even in QED.[4] The basic reason for this is that a single plane wave of a given energy may always be viewed in a different reference frame, where it has less energy (the same is the case for a single photon)."

So according to QED, we can actually make a laser of any power – and as long as its in a vacuum, there are no non linear effects. Can that really be true?

The Schwinger limit is about 2.3 E33 Watts/metre^2.

I have calculated the limit of gravitational wave energy (which depends on frequency) to be

P (max gravity waves) = 3/(5pi)*c^3/G*w^2,

In Electromagnetism, QED says that the linearity of Maxwell’s equations comes to an end when field strengths approach the Schwinger limit. Its about 10^18 V/m.

What is the corresponding formula for gravitational waves. Since gravity is a non-linear theory, there should be a point where gravitational waves start to behave non linearly.

Here is my calculation, based on http://en.wikipedia.org/wiki/Gravitational_wave:

There is a formula there for the total power radiated by a two body system:
(1) P = 32/5*G^4/c^5*m^5/r^5 (for identical masses in orbit around each other)

Further down the same wiki page I see a formula for h, which has a max absolute value of (assuming h+ and standing at R = 2r away from the system, theta = 0):

(2) h = 1/2*G^2/c^4*2m^2/r^2

Things will be highly non linear at h = 1/2 (which is the value of h used in the diagram on the wikipedia page!). So lets set h = 1/2, and then substitute (2) into (1) to get the power as radiated by the whole system when h = 1/2 (use a lower value like h = 0.001 perhaps to be more reasonable, if you like). I am not trying to calculate where the chirp stops in a binary spin-down here, I’m looking for the maximum field strength of a gravitational wave.

I get for the maximum power from a compact source

(3) P = 64/5*c^3/4*m/r

That’s the total power radiated when h is well into the non linear region – you will never get more than this power out of a system using gravitational radiation.

The result depends on m/r , which makes sense as higher frequency waves with the same value of h carry more power.

Putting the result in terms of orbital frequency, w, we get (using newtonian orbit dynamics (http://voyager.egglescliffe.org.uk/physics/gravitation/binary/binary.html)

(4) Pmax = 16/5 c^3/G*w^2*r^2

That’s the max coming out of a region r across, we want watts per sq metre, so divide by the surface area of a sphere:

(5) Pmax/per sq meter = 3/(5*pi)*c^3/G*w^2

The maximum power that you can deliver at 10^14 Hz (light wave frequencies, so as to compare to the E&M QED Schwinger limit) is 10^65 watts/m^2 !

That’s a lot of power, dwarfing the Schwinger limit.

Is that about right? The max power scales as the square of the frequency, and is truly huge, reflecting how close to linear GR is over large parameter spaces.

w = frequency

So for gravitation, we have linear behavoir holds up until some fantastic power level:

http://www.wolframalpha.com/input/?i=c%5E3%2FG*%28%285*10%5E14%29%5E2%29%2Fsec%5E2

1e65 watts per sq metre at visible light frequencies is about the linear limit for gravitational waves at a frequency of 10^14 .

This means that gravity has ‘lots of headroom’ to create the phenomena of electromagnetism.

Perhaps one could dream up a super efficient way to generate ‘normal’ quadrupole gravitational radiation using some radio sources arranged in some way. Or a way to generate anti-gravity, etc.

GR certainly has a large enough range of linearity to power all of the EM we know today. Its also possible to generate monopole and spin 1 radiation from gravity, look up Brady’s papers on EM generation from simple compressible fluids, for instance.

Also do the joules/sec per square mm or whatever calc.

Also look at some other consequences in the dark recesses of the proton and electron (my models of them, or effects just based on size and field levels).  Would we start to get non-linear EM effects at what distance from the centre of an electron? Same for quarks?

http://en.wikipedia.org/wiki/Gravitational_wave

http://voyager.egglescliffe.org.uk/physics/gravitation/binary/binary.html

Ref http://www.jetp.ac.ru/cgi-bin/dn/e_038_04_0652.pdf