Frank Wilczek's Vision: Exploring Grid Theory & Quantum Gravity

[marcus]

Frank Wilczek has presented a way of looking at the world which is curiously consonant with Lattice Quantum Gravity approaches a la Renate Loll, John Barrett, Lee Smolin, Carlo Rovelli and others. The world as lattice---what Wilczek calls the Grid.

It is oddly reminiscent of spin networks and their evolution as spinfoam in LQG. Wilczek's vision is background independent in the sense that it does not start with any static concept of space as a stage set for other entities to move around in. Dynamics is not the motion of entities in a static space, but is the dynamics of space itself. The stage becomes the principle actor in the play. This idea is at the heart of contemporary non-string quantum gravity. It is also what Wilczek has developed, coming from a different direction.

Wilczek carries this idea a long ways. His ideas will, I think, resonate and inspire people interested in quantum gravity. So what is Wilczek's overall vision?

Mental images and analogies are mostly wrong and just confuse people, but from time to time a great physicist will teach us a new way to look at the ground of being---a profound new vision of space and matter. Frank Wilczek proposes looking at empty space as the Grid, with particles merely being disturbances in the Grid.

What we might think of as properties of separate particles are more coherently seen as properties of the Grid. In particular, particle masses are explained by a process analogous to superconductivity. Particles are given mass by how the Grid responds to them.

But look, the 1915 Einstein equation of GR was the first equation that linked matter (on the righthand side) with the geometric response of the Grid (on the lefthand side). We always knew this in a sense. Mass (both gravitational and inertial) is how it interacts with geometry---both how it shapes geometry and, in turn, is guided, told by inertia how to move. Didn't we always suspect what Wilczek is now telling us, in greater revelatory detail?

You could say that Wilczek is pushing a new paradigm (that should set the buzzword buzzers off!). But I think it is much simpler than that----he is, in pragmatic spirit, drawing a practical conclusion from the success of lattice calculations and the standard model. It works, so let's think of the vacuum as a lattice and imagine matter fields as disturbances therein.

Out of this, Wilczek gets a kind of new background independent* ontology, and a take on where presentday fundamental physics is in the history of physics. He has written it up in various places. One can google with terms like Wilczek and Grid. (Maybe "multicolored superconductor" would also work )

*what I mean by this is what quantum gravitists frequently mean, no reference to any fixed background metric geometry. More generally, space itself is dynamic, not a set stage but the major actor in the play. Call it "the Ether" if you like and worry about how Lorentz invariance is preserved later.

==============
I'll get some links later. Have to go out.
If anyone has comment on Wilczek's vision of fundamental physics, or links to his writings, please contribute. Would love to hear comment on F.W. ideas.

 

[marcus]

Back now (had to be out for a few hours).
the first Wilczek link we should explore is his 2005 Nobel speech, published in the Proceedings of the NAS
http://www.pnas.org/content/102/24/8403.full
Everything I'm talking about is in essence here or foreshadowed. And there is a lot more. Rereading it I see there is a lot more here than I saw back 3 years ago. It's a good speech because since he is speaking to peers he lays his thoughts out concisely and completely, without as much analogy and paraphrase as one gets in popular writing.

Here is a sample portion of that speech. One section of the speech is called "A Foursome of Paradigms", and this is part about Paradigm #2:

==quote==
Paradigm 2: Mass Comes from Energy. My friend and mentor Sam Treiman liked to relate his experience of how, during World War II, the U.S. Army responded to the challenge of training a large number of radio engineers starting with very different levels of preparation, ranging down to near zero. They designed a crash course for it, which Sam took. In the training manual, the first chapter was devoted to Ohm's three laws. Ohm's first law is V = IR. Ohm's second law is I = V/R. I'll leave it to you to reconstruct Ohm's third law.

Similarly, as a companion to Einstein's famous equation E = mc^2, we have his second law, m = E/c^2. Here, of course, E denotes the energy of a body at rest, and m its mass.

All this isn't quite as silly as it may seem, because different forms of the same equation can suggest very different things. The usual way of writing the equation, E = mc^2, suggests the possibility of obtaining large amounts of energy by converting small amounts of mass. It brings to mind the possibilities of nuclear reactors, or bombs. Stated as m = E/c^2, Einstein's law suggests the possibility of explaining mass in terms of energy. That is a good thing to do, because in modern physics energy is a more basic concept than mass. Actually, Einstein's original paper does not contain the equation E = mc^2, but rather m = E/c^2. In fact, the title is a question: “Does the Inertia of a Body Depend Upon its Energy Content?” From the beginning, Einstein was thinking about the origin of mass, not about making bombs.

Modern QCD answers Einstein's question with a resounding “Yes!” Indeed, the mass of ordinary matter derives almost entirely from energy—the energy of massless gluons and nearly massless quarks, which are the ingredients from which protons, neutrons, and atomic nuclei are made.

The runaway build-up of antiscreening clouds, which I described before, cannot continue indefinitely. The resulting color fields would carry infinite energy, which is not available. The color charge that threatens to induce this runaway must be cancelled. The color charge of a quark can be canceled either with an antiquark of the opposite color (making a meson), or with two quarks of the complementary colors (making a baryon). In either case, perfect cancellation would occur only if the particles doing the canceling were located right on top of the original quark—then there would be no uncancelled source of color charge anywhere in space, and hence no color field. Quantum mechanics does not permit this perfect cancellation, however. The quarks and antiquarks are described by wave functions, and spatial gradients in these wave function cost energy, and so there is a high price to pay for localizing the wave function within a small region of space. Thus, in seeking to minimize the energy, there are two conflicting considerations: to minimize the field energy, you want to cancel the sources accurately; but to minimize the wave-function localization energy, you want to keep the sources fuzzy. The stable configurations will be based on different ways of compromising between these two considerations. In each such configuration, there will be both field energy and localization energy. This gives rise to mass, according to m = E/c^2, even if the gluons and quarks started out without any nonzero mass of their own. So the different stable compromises will be associated with particles that we can observe, with different masses; and metastable compromises will be associated with observable particles that have finite lifetimes.

To determine the stable compromises concretely, and so to predict the masses of mesons and baryons, is hard work. It requires difficult calculations that continue to push the frontiers of massively parallel processing. I find it quite ironic that, if we want to compute the mass of a proton, we need to deploy something like 10^30 protons and neutrons, doing trillions of multiplications per second, working for months, to do what one proton does in 10-24 seconds, namely figure out its mass. Maybe it qualifies as a paradox. At the least, it suggests that there may be much more efficient ways to calculate than the ones we're using.

In any case, the results that emerge from these calculations are very gratifying. They are displayed in Fig. 4. The observed masses of prominent mesons and baryons are reproduced quite well, stating from an extremely tight and rigid theory. Now is the time to notice also that one of the data points in Fig. 3, the one labeled “Lattice,” is of a quite different character from the others. It is based not on the perturbative physics of hard radiation, but rather on the comparison of a direct integration of the full equations of QCD with experiment, using the techniques of lattice gauge theory.
[Fig. 4]
The success of these calculations represents the ultimate triumph over our two paradoxes:
1.The calculated spectrum does not contain anything with the charges or other quantum numbers of quarks; nor of course does it contain massless gluons. The observed particles do not map in a straightforward way to the primary fields from which they ultimately arise.
2.Lattice discretization of the quantum field theory provides a cutoff procedure that is independent of any expansion in the number of virtual particle loops. The renormalization procedure must be, and is, carried out without reference to perturbation theory, as one takes the lattice spacing to zero. Asymptotic freedom is crucial for this, as I discussed—it saves us from Landau's catastrophe.

By fitting some fine details of the pattern of masses, one can get an estimate of what the quark masses are and how much their masses are contributing to the mass of the proton and neutron. It turns out that what I call QCD Lite— the version in which you put the u and d quark masses to zero, and ignore the other quarks entirely—provides a remarkably good approximation to reality. Since QCD Lite is a theory whose basic building blocks have zero mass, this result quantifies and makes precise the idea that most of the mass of ordinary matter—90% or more—arises from pure energy, via m = E/c^2.

The calculations make beautiful images, if we work to put them in eye-friendly form...some striking animations of QCD fields as they fluctuate in empty space...
[Fig. 5.]
A snapshot of spontaneous quantum fluctuations in the gluon fields. ... (Image courtesy of Derek B. Leinweber, CSSM, University of Adelaide... www.physics.adelaide.edu.au/theory/staff/leinweber/VisualQCD/Nobel.)
[Fig. 6.]
The calculated net distribution of field energy caused by injecting and removing a quark–antiquark pair. By calculating the energy in these fields and the energy in analogous fields produced by other disturbances, we predict the masses of hadrons. In a profound sense, these fields are the hadrons. (Figure courtesy of G. Kilcup.)

These pictures make it clear and tangible that the quantum vacuum is a dynamic medium, whose properties and responses largely determine the behavior of matter. In quantum mechanics, energies are associated with frequencies, according to the Planck relation E = hν. The masses of hadrons, then, are uniquely associated to tones emitted by the dynamic medium of space when it disturbed in various ways, according to Formula We thereby discover, in the reality of masses, an algorithmic, precise Music of the Void. It is a modern embodiment of the ancients' elusive, mystical “Music of the Spheres.”
==endquote==

 

[granpa]

http://arxiv.org/pdf/hep-ph/0201222

 

[marcus]

thanks granpa!
that's an excellent article, which fits right in here, and also it elaborates on two or three of my favorite Physics Today articles by Wilczek. Now we don't need separate links to those Physics Today pieces (Scaling Mt. Planck...)
for convenience, I will show the abstract:
http://arxiv.org/abs/hep-ph/0201222
Four Big Questions with Pretty Good Answers
Frank Wilczek
19 pages, talk given at a Symposium in Honor of Heisenberg's 100th birthday, December 6, 2001, Munich; to be published in the Festschrift
(Submitted on 23 Jan 2002)

"I discuss four big questions that can be importantly addressed using concepts from modern QCD. They concern the origin of mass, the feebleness of gravity, the uniqueness of physical laws, and the fate of matter when it is squeezed very hard."

 

[Fra]

Sorry to come up with this possibly annoying question but, perhaps others wonder the same thing but knows better than asking it.

How is this "grid" to be though of attached to the identity of an observer - which would suggest that the grid is possibly not unique and that it rather exists a class of grids, who is interacting (ie interaction observers/matter systems), and that the grids are only compared by means of communication/interaction? (a little bit like rovelli argues about emergence of objectivity from communication in his relational QM) or is the grid supposed to be some invariant of the class of observers, or fixed background reference? But in case of the latter, then we seem to get the problem of time still, if we are to describe disturbances in this grid, this description must relate to an inside observer, right?

Or could it mean - which I would personally find intriguing and worth expanding on - that these nature of what marucs called "disturbances" in the grid could infact be seen as a sort of "inconsistency" in the grid, due to the problem above, of how to attache the grid to different systems - ie. two different systems (particles) have an "idea" of this grid, and their interaction is a result of seeing the other party as inconsistent with their own state, and this drives the interaction and time evolution. The idea could be that the inconsistencies are only relative in nature, and measures from respective grid, each party take actions on this?

Or how would you conceptually think of this grid, and in what way it solves problems?

/Fredrik

 

[marcus]

Fra, those are such good questions! Thank you for adding them in here, I will keep an eye on them although I cannot reply immediately. Because I am just now beginning to appreciate how Wilczek thinks---or what message he is putting out for the rest of us.
His style is both playful and insightful, and at the same time truthful---he goes all out to crank up the reader's level of imagination while at the same time stay connected with empirical predictive observational honesty. For some answers, the best thing is probably to refer you to his personal website.

Wilczek has a website where he has posted some of his writings, including essays that talk about this Grid=Ether=Dynamic Space=Superconductor-analog thing. One of the best is a 2003 essay you can find here on a page called "core":
http://www.frankwilczek.com/core.html

Wait. It is better to see the whole website by going top down:
http://www.frankwilczek.com/
You will see that he actually has posted a sample of his new book--he has Chapter 1 of Lightness of Being on line!
http://www.lightnessofbeingbook.com/inside.html
If you go to this you will see he has not only the Table of Contents of the book online, but also Chapter 1 as a sample, and color plate illustrations from the book etc.

But also at the website are many previously published essays which describe his thinking and which he evidently combined and elaborated and expanded and popularized to make the book. Essays like his Nobel acceptance speech, and this 2003 essay called The Origin of Mass

If you go to that page called "core" (again the url is http://www.frankwilczek.com/core.html )
you will see a menu of seven PDF files. Seven essays as a sample of a book of 40-some essays that he published several years ago.
==quote from "core" menu of PDF essay files==

When Words Fail
Langauge builds in assumptions about reality that we must question.
World's Numerical Recipe
How to instruct a computer to cook up the physical world using numbers -- getting Its from Bits.
In Search of Symmetry Lost
The most beautiful equations seem too good for this world -- but maybe not!
QCD Made Simple
"As simple as possible", within the bounds of honesty. (Look ma, no equations!)
Quantum Field Theory
Describing the conceptual roots and the deep consequences of physics' most profound theoretical construction.
Asymptotic Freedom: From Paradox to Paradigm
My Nobel Prize lecture. How asymptotic freedom solved the strong interaction, and opened up important new frontiers.
The Origin of Mass
An earlier, concise discussion of some main themes in Part 1 of The Lightness of Being, with nice graphics.
==endquote==
Here is the PDF for The Origin of Mass
http://www.frankwilczek.com/Wilczek_Easy_Pieces/342_Origin_of_Mass.pdf
This essay gives an idea of what is in Chapters 1 thru 12 of the book, "Lightness of Being".
(after all Lightness is the same thing as Mass, just measured inversely. Whatever determines lightness is the same as the origin of mass. The title jokes in a multireferential way, echoing other things as well.)

I think "Grid" is a vague idea. It is important sometimes for ideas to be vague. It can be identified as the Einsteinian metric of GR, the gravitational field---which at one point Wilczek calls "the Mother of all Grids". The basic field on which other fields are defined.
He also describes how the Grid works by analogy with a superconductor--giving things their properties by how it responds to them--the essence is in the response.

The Grid can also be identified as the Einsteinian ether. Whatever it is, it is the ground of being----it gives other things their mass---and everything else, all the other properties---but mass is like the mental doorway. If you can see how the dynamic geometry of space might give things mass (a hard stretch of imagination) then by adding other colors and layers you might get a glimpse of how it confers other properties as well.

As a gifted explainer, he begins by concentrating his forces on one problem, the origin of mass. This is the oldest recognized most basic classic Newtonian property of matter. If we can understand how space (grid, ether, etc) gives things mass then maybe we can grasp the rest. So that is how he organizes his campaign to stretch our minds.

The Origin of Mass was published in the 2003 MIT Annual Review of Physics, and also in his collection of essays called Fantastic Realities. Fortunately, it is also immediately available online at his website.

 

[atyy]

There's some videos of his talks on his webpage:

http://web.mit.edu/physics/facultyandstaff/faculty/frank_wilczek.html

He apparently tells Einstein's favourite joke about an hour into "The Universe is a Strange Place".

 

[marcus]

That is such a fine video!
http://mitworld.mit.edu/video/253/
I guess it's my favorite physics video. Maybe yours too? Thanks for the link, atyy.
==quote from abstract==
Perhaps the universe is not so much strange as brimming with lovely paradox. The search for such beauty seems to lie at the heart of Frank Wilczek’s work. Twentieth century physics, from Einstein through Wilczek’s own Nobel Prize-winning efforts, involves demonstrating the existence of a topsy-turvy reality: for instance, that such sub-atomic particles as quarks and gluons, which have little or no mass, “orchestrate themselves into not just protons and neutrons but you and me,” according to Wilczek. “How is it possible to construct heavy objects out of objects that weigh nothing?,” he asks. Only by “creating mass out of pure energy.” These particles are essentially “excitations in otherwise empty space.” Says Wilczek: “That suggests something …beautiful and poetic: the masses of particles are not like, or similar to or metaphorically suggested by—they are the tones or frequencies of vibration patterns in dynamical voids.” The theory of quarks and gluons and the strong interaction accounts quantitatively for “the mass of protons, neutrons and ultimately you and me and everything around us.” But physics has not yet squared away all aspects of the universe. Wilzcek says that “in cosmology, we meet our match, and don’t know what’s going on.” This is because scientists can’t account for much of the mass in the cosmos. 70% of this mass is in “dark energy,” which is pushing the universe apart. Wilczek hopes that explanations for the dark stuff will emerge through improving equations, unifying theories of different interactions and extending their symmetries. “Beautifying equations leads not to ugly consequences but beautiful surprises,” he concludes.
==endquote==

 

[Fra]

I read Wilczek's "The origin of mass" in the tub last night. It was a good essay.

His answer seems to be that as per the current models, "most mass" except for the quark rest masses which is a minor part, is basically "confined energy" (gluons), which adecomposes the problem into

1. The origin of energy
I think this question is interesting if you try to construct the measures of these, from the point of view of an inside observer. I see this question of epistemological nature so that if not else, it means what is the origin and nature of *energy measures*.

2. The origin of *confinement* of energy
since "confinement" implicitly refers to constraining distribution of energy over degrees of freedom, and thus the question propagates into the origin of these degrees of freedom in the first place. And in this case this structure apparently is spacetime. So again we get back to the entanglement of Einsteins, which entangles these notions with properties of spacetime.

It seems wilczek's argument is to have QCD be the answer to the confined energy of the gluons in the hadrons. But as I understand it at least, the entire framework of QCD rests upon a spacetime concept, so there is still an element of circularity. So his argument so far is nice but incomplete. Like he mentions in the end, this may partially explain in a restriced sense most mass, but it seems to me that hard parts (the hardest?) of origin of mass remains.

Does anyone understand or see if Wilczek has continued this reasoning beyond these points (which I find plausible) to probe for answering the remaining problem, which I personally expect lines in this apparently "circularity".

It seems the things missing in Einsteins reasoning, is the structure of the observer. The only observer classes he considers are those where the observer are generated by diffeomorphisms. One can't help thinking this is a simplificiation, as in "moving the same observer around". But the internal structure of the observer, are can also "move around" right? And how can that not, impact it's observables?

This seems like a simple problem, but seemingly yet unresolved?

I will read more in Wilczek later... my imagination took a spin from marcus firsts posts, where did see a remote chance that a continuation of the grid-fuzz, might be able to address some of the remaining harder questions!? I will try to read more and add more reflections later.

I want to thank Marcus for all his massive work on starting and digging up various papers and possible original lines of thought, in this and many many other threads! In particular for me who is not having this as a profession I have no chance to keep up with reading everything(I don't even have enough time for my own thinking), so I really value many of the threads where marcus has started it as a presentation of selected particular researchers line of reasoning (relevant to beyond standard model, and fundamental issues), that all might contain different angles on the general problems at hand. Many of these threads has also lead to interesting reflections from the various members on here.

/Fredrik

 

[marcus]

I read Wilczek's "The origin of mass" in the tub last night...

Hah! You and Archimedes. Both thinking about mass while soaking in the tub. What better place?

Thanks for the approval and encouragement. BTW I ordered Wilczek's new book and put the link in my sig.

 

[yuiop]

I read somewhere in this forum (although I can not locate it right now) that Einstein was working on a concept of mass that takes the mass energy equivalence literally. The basic idea was that all mass is just a disturbance of a background energy field, or that mass is just a way that certain patterns of energy manifest themselves. Particles are not localised in the way we normally think of but are composed of energy that is spread out possibly to infinity and in this concept, what we think of as a particle is just where the enrgy is most concentrated. In effect there is no such thing as mass, just patterns of energy. Particles are much "fuzzier" than we normally think of and are smeered out over vast distances much in the way we think of a gravitational field or the curvature of space, except the particle IS the field or part of the field and particles separated by great distances are in effect superimposed on each other. One anology is to think of the rubber sheet embedding diagram. The normal visulisation is "cannon balls" resting on the rubber sheet indetting and deforming the sheet. The mass is energy visulisation does not have the cannon balls, and the particles are the indentations rather than the cause of the indentations. Sorry this all a bit vague, but I read the article a while ago and can not rememember all the details and can not track down a reference. The point is that the "mass REALLY is just a manifestation of energy" idea of Einstein's sounds a lot like the idea of Wilczek being discussed here. Can anyone here track down Einstein's original idea and compare how it similar to that of Wilczek and how it differs?

 

[granpa]

Lorentz thought that all or at least most of the electrons mass could be accounted for by its magnetic field. unfortunately it never quite worked out.

 

[MTd2]

"Strings, quantum gravity and non-commutative geometry on the lattice
Authors: J. Ambjorn
(Submitted on 9 Jan 2002)

Abstract: I review recent progress in understanding non-perturbative aspects of string theory, quantum gravity and non-commutative geometry using lattice methods."

http://arxiv.org/PS_cache/hep-lat/p...cs.umich.edu/~crshalizi/notabene/tsallis.html

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

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

 

[Fra]

I tried to look at his site specifically for expansions on "the grid". I am starting think that perhaps his new book is the one place which might contain this? Does that seen right, or have I missed something? I didn't see on a quick rush on his site much use of the word grid in his papers. On google it seems to associate to that book mainly.

I found this http://www.frankwilczek.com/Wilczek_Q_and_A.pdf saying this about the grid:

You say that recently the laws of physics have changed, not just in detail but in kind. What do you mean by that?
Prior to the twentieth century, physics tried to explain how Nature works. Over the twentieth century, and especially in the last half, we got much more ambitious - now we’re uncovering what Nature is.

And what is it?
The foundation is an entity I call the Grid. The Grid fills space, and is full of spontaneous activity. In some ways it resembles the old idea of “ether”. But the Grid is highly evolved ether, ether on steroids if you like, with many new features.

It sounds intriguing and I'm curious to hear from Marcus when he has looked at the book to what extent these ideas are expanded upon in the book.

He says the grid "fills" space which at first sounds like considering space as a container in which the grid goes. But perhaps it is better interpreted as space as defined by the state of the grid. Then one might say thta the grid fills space, but still, no grid no space, right?

/Fredrik

 

[Fra]

I thought about this again and it sounds somewhat controversial. The first time I read it I thought he said something else. How do you interpret this?

You say that recently the laws of physics have changed, not just in detail but in kind. What do you mean by that?
Prior to the twentieth century, physics tried to explain how Nature works. Over the twentieth century, and especially in the last half, we got much more ambitious - now we’re uncovering what Nature is.

The thoughts that appeared to me is that sometimes many say, in Niels Bohr's spirit, that the quantum revolution is a switch from the quest for "what nature is" to "what we can say about nature".

I'm not how that is to be merged with what Wilczek says here, and where in this, is the new golden age view?

How about something like this

1. In the pre 20th century we asked ourselves what nature is and how nature works.

2. In the 20th century and the revolution of QM, we started to ask instead (à la Bohr) what we can say about nature, and how it works.

Now what is the next revolution, of the 21th century? If I may fill in the blanks, how about(?)...

3. We start to ask about the nature of "what we can say" about nature, and specifically the problem that "WE" refers to an observer, and thus the question of "the nature of observers" really aims to expand upon the 2nd revolution in the sense that we look close at the nature of "observation", and what is the nature and BASIS for "what an observer can say" about nature?

Is this possibly what Wilzcek means? If not, what he say seems to be a step back, and not a step forward?

Let me know how you others would think of this "next revolution", that I assume is sniffed here.

/Fredrik

 

[Fra]

And of course, in the end this may close the circle, in that what "nature is" is simply this, the matter we observe, are "observers" too. So the nature of things is "the nature of these relations"?

/Fredrik

 

[Vrareti]

So about this Grid.. Is it like a simple grid? Like lots of intersections and sides? What shape does it have? How many dimensions? Is it a hypercube? A cube? Is mass a property of the intersections or the sides? Am I understanding this correctly or am I thinking about something completely different?

 

[pelastration]

He says the grid "fills" space which at first sounds like considering space as a container in which the grid goes.
/Fredrik

Seems to me as the container is the grid. Massless.
And the grid/container is dynamic, and only energy.
Where by a kind of entanglement the grid "makes" massless gluons and nearly massless quarks. They combine to protons, neutrons.

 

[marcus]

Multilayered multicolored cosmic superconductor (Wilczek's Grid as ground of bein

So about this Grid.. Is it like a simple grid?...

Vrareti, the quickest way for you to find out what he is talking about is to go here:
https://www.amazon.com/dp/0465003214/?tag=pfamazon01-20
and simply read free online sample pages of the book.

when you go to that amazon.com web page there is an icon picture of the book at the upper left corner, and an arrow with a sign saying "look inside". If you click on the icon you will get a menu accessing (I estimate) some 30+ sample pages. the table of contents. Chapter 1. the index. and something called "surprise me". If you click on the surprise sample item repeatedly, you will get selected sections of the book.

The part where he introduces the idea of the grid, he is talking about the familiar flat map of a spherical surface (the Mercator projection map of the world that we all know).
Remember it is a wide-audience book. The language is non-mathematical, non-technical. He uses metaphors. He doesn't say "manifold", he wants to introduce the idea of the METRIC on a manifold----a means of calculating distances. On a Mercator-type map, the grid of lines contains information for calculating distances. On a Mercator-type map the grid of lines is the metric of a certain smooth manifold.

Maybe you know this about General Relativity: in GR the gravitational field is the metric, and there is no space or spacetime except the metric itself. Einstein defines gravity as geometry, represents geometry by a metric (i.e. a Grid function or distance function) and then throws away the points of spacetime---points of spacetime have no physical reality.
The metric (or if you want, metaphorically, the Grid) is the basic field.
Other fields are defined on that basis. And the metric (the gravitational field) is dynamic. Geometry is dynamic. There is no fixed geometry. You get geometry by solving the Einstein field equation. It is a radical departure from Newtonian physics and Wilczek wants to bring even wide-audience readers quickly up to speed on it.

General Relativity was the first physical theory formulated without a fixed geometric background. It is the paradigm for background-free, or background-independent, physics.
Early in the book---you can read this in the free amazon sample sections---he is introducing the Grid idea and he refers to the Einstein GR metric as "the Mother of all Grids".

In other words, the gravitational field (i.e. the GR metric) is the paradigm for what he means by Grid. But the GR metric is not a lattice, technically speaking. It can be represented by various styles of lattice together with rules of interpretation, but it is something more abstract and general. So the paradigm Grid (or the Mother of all Grids) is not technically a lattice---it is a dynamic responsive idea of empty space.

That is the essential core idea in GR. Empty space, which is nothing but geometry itself, can be responsive. The 1915 Einstein field equation says how it responds to matter. The lefthand side is geometry, the righthand side is matter (the energy/momentum of matter.)

Wilczek's vision is "let's do ALL physics in a background independent way", not just gravity physics. Let's enlarge the idea of empty space, make it multicolored and multilayered, with more degrees of freedom, so it responds to more than just energy/momentum.

Because he is talking to a wide audience, he concretizes the idea of a dynamic responsive geometry----the idea of empty space as the main actor rather than a set stage---by calling it Grid. Grid is a good one-syllable word to use. The basic metaphor comes from the grid-lines on a Mercator-type map that everybody knows.

A lot of the book is about empty space. He accelerates the reader very fast into a GR way of thinking---a background independent way of thinking where there is no rigid fixed geometry but empty space is, in a sense, "live". I find his style completely unmystifying.
The style is concrete and practical. Think of it this way because it works. And he avoids long technical-sounding words such as we normally get in this context. Brilliant book.

You should read the samples directly though---my paraphrase will only make it less intuitive for you.

 

[Fra]

Thanks for the elabrations, I think I see what he means by the grid, and I see the similaritiy with rovelli's thinking. (I seem to have exhausted my surprise sampling on amazon? it didn't work for me)

Then I'd keep asking as in post #5

"How is this "grid" to be though of attached to the identity of an observer"

I can't help getting back to that as a key question. I am not sure if the classical GR view of this will do (although it probably holds half the solution), because there somehow "the grid" would be an objective (although relative, and dynamic) thing?

Unlike what rovelli, I doesn't feel confident in assuming that the problem of his excellent idea of "communication between observers" (in his relational QM; http://arxiv.org/abs/quant-ph/9609002) can be dismissed as beeing "quantum mechanical in nature". I interprete this idea of reasoning so that in despite of acknowledging he relational nature of many things, at some levels we still think there is something like an observer invariant version of the relations between the relations.

Of course if this is so, it would be even better, but seems to me like a fragile paradigm.

I think this paradigm is the problem of merging things. GR is after all, although a deep theory, formulated in a classical spirit of realism (that's at least how I see it). Therefor I've always felt that this deep relational idea of GR, needs to be reworked as to keep the relational spirit but the theory itself formulated in terms of an observer view, or the theory doesn't seem to be unique.

What I mean is this: GR realizes the relativity of some measurements, but this is recovered by the connections (observer-observer transformations). These "connections" are then treated in the same classical spirit. Is this not a problem?

If it is not, it is not surprising if it's not addressed.

I noticed that this book was relatively unexpensive, so I might keep it in mind for the next round. But I'm still piled up with othre books I planned to read first. There is an phsycological stress when the pile of to-read books on your bedside grows so high you can't see the alarmclock on the left of it :grumpy:

/Fredrik

 

[MTd2]

It can be represented by various styles of lattice together with rules of interpretation, but it is something more abstract and general. So the paradigm Grid (or the Mother of all Grids) is not technically a lattice---it is a dynamic responsive idea of empty space.

Does it correspond to what I wrote?

*feels ignored*

 

[marcus]

Seems to me as the container is the grid. Massless.
And the grid/container is dynamic, and only energy.
Where by a kind of entanglement the grid "makes" massless gluons and nearly massless quarks. They combine to protons, neutrons.

Chapters 1-12 are a section called the Origin of Mass and he has a separate essay with the same title that is online, that you can read without buying the book. It says something like what you just said, maybe not exactly, but parallels it. In QCD, the way he describes it,
the Grid gives mass to nearly massless quarks by how it responds to them and to gluons, in a process analogous to superconductivity.

The way he tells the story, his whole way of thinking about the Grid was inspired by his experience with QCD. The dynamic container----empty space as an active partner. Then thinking by analogy with his success in QCD he gets a vision of bridging over to other parts of physics---like gravity (where the dynamic container is the GR Metric) and like the Higgs mechanism (where the dynamic container is the Higgs field).

I think you probably said it right in a few words and I am just elaborating, with more words.

Does it correspond to what I wrote?

You mean post #13, a ways back, where you mentioned Tsallis entropy, and a 2002 CDT paper by Ambjorn. I couldn't see a connection with Tsallis but maybe someone else can. About Ambjorn, I think he got started in string theory may have gotten into dynamical triangulations (DT) as a way of finding a background independent formulation for string. He worked in lattice-type stuff for quite a few years before (1998) teaming up with Loll and inventing Causal DT. The 2002 paper talks about hopes and directions for further research and not everything panned out. The one thing he mentioned in the 2002 paper that DID work out was CDT quantum gravity for d = 4. So Ambjorn and Loll have become known for that. I don't see a clear bridge between their CDT and, say, QCD. If there were that would, of course, be wonderful---you could say it would be at least a partial implementation of Wilczek's idea of future of fundamental physics, his Grid idea.

 

[MTd2]

1.I couldn't see a connection with Tsallis but maybe someone else can.
2. I don't see a clear bridge between their CDT and, say, QCD. If there were that would, of course, be wonderful---you could say it would be at least a partial implementation of Wilczek's idea of future of fundamental physics, his Grid idea.

1. Entropy for the hausdorff dimensions of small Loll's universe dimension. You may need entropy to define energy.

2. A.QCD-emerge mass(that Wilzcek wants to be a literal materialization of energy, like einstein wanted). B.CDT- emerge space/time. C.GRID- space time analog to superconductivity in QCD.

So, in a very vague analogy, C relates B and A...

The thing in common in #2 is emerging from a lattice, whose grid spacing goes to 0. That's weird, like everything is something left from the Grid, or something.

 

[Fra]

Then I'd keep asking as in post #5

"How is this "grid" to be though of attached to the identity of an observer"

Since it seemed to me that some keys were, as with rovelli's thinking, in the meaning of QM, I skimmed this paper to get a glimpse of his view of QM. It is a short essay and not near as elaborate as rovelli's relational QM, althogh from reading this I would suspect the Wilczek would like Rovelli's thinking...

What is quantum theory?
-- http://www.frankwilczek.com/Wilczek_Easy_Pieces/317_What_Is_Quantum_Theory.pdf

He makes comparasions to maxwells theory and relativity amongs other things notes about the obscureness of QM regarding collapse of wavefunctions etc.

"I believe it will remain so until someone constructs, within the formalism of quantum mechanics, an "observer"", that is, a model entity whose states correspond to a recognizable caricature of conscious awareness; and demonstrates that the preceived interaction of this entity with the physical world, following the equations of quantum theory, accords without expecrience. That is a formidable project, extending well beyond what is conventioanlly considered physics. Like most physicists, I assume, perhaps naively, that this project can be accomlished, and that the equations will survive it's completion unscathed."

I share the vision of construction a model of the observer states, but I think the word "consciousness" usually gives this a negative tone.

About the origin of quantum theory, and the motivation behind the commutator relations as phrased by Dirac he notes

"I think it is fair to say that one does not find here a profound guiding principle, comparable to the equivalence of different observers (that inspires both relativity theories) or of different potentials (that implement gauge invariance)."

The he asks this

"Is it possible to phrase the equations of quantum theory as a statement of symmetry?"
(similar to GR and SR that is)

The he summarizes with

"we are still two big steps away from understanding quantum theory properly"

I personally do not think the equations will survive unscratched though. But I do believe in a symmetry formulation of QM, with I think it will be an emergent symmetry rather than a fundamental one.

My opinion that is in line with this is to consider ALL interactions (quantum as well as gravity) are a result of interacting observer states. The problem seems to be that even the description of this is also encoded in the observers states. But I think this could go from problem to key, and explain why we get unification as the complexity of the observers goes to zero.

/Fredrik

 

[Fra]

I'm not sure I got your main points but some personal reflections on this

We know that the formultion of feynmann integal is related to thermodynamics, so, maybe, using that kind of entropy, it would be possible to define feynmann integral in a hausdorf space and make calculations on the lattice easier?

may need entropy to define energy.

Set aside CDT, I think this focus is interesting. I am of the opinion that we have not understood the full meaning of these path integrals yet, which is pretty much the same questions as understanding the origin of "quantum mechanics". "We use it because it works" is certainly correct but it doesn't answer some of the deeper questions.

As I see it there are at least three somewhat mysterious measures around. Entropy, action and energy. If you suggest these are related in a way we yet don't undersand I agree completely what that view.

A problem is that the traditional way is to defined these things in the context of classical mechanics and ordinary stat mech, and that patching onto this with various tricks - although it apparently "works" - is not satisfactory.

I think we probably need a fundamental revision of statistics, and it's various meausures.

One association I make with energy and entropy, is to first ask what entropy is supposed to measure? Once you ask that you also see that there are a whole range of different entropies, and one way or the other it boils down either to a concept of "continuum probability" or a concept of combinatorics and complexions. So the question is, how does one distinguish a distribution or a microstate? This somehow leads us to consider the distribution spaces or microstructures also as "states", and then I think similar to statistcal reasoning, each state or distribution needs to be measured to what extend it's identified, relative to the next level of structure. Here is where I am trying to associate energy or mass. The difference may just be that of confinement to degrees of freedom, other than than mass an energy can be thought of as the same thing.

In this view, there is a relation between measure of disorder and measure of identity. An identity that can barely be identified, can be reated in disorder at different levels. I think most entropies we use, like shannons, does not acknowledge the limited confidence in the the microstructure itself. I think one can not with certainty assing a measure to something, that is onyl vaguley distinguished.

I think the action, can be understood as a generalised form of "entropy" where time evolution is more like a simple diffusion.

So I think that the measures, energy and entropy are related and constrains each other, and there are currently problems here in the standard formalisms. And in the extension that I have in mind, these things is just a special case of a general statistics which incorporates actions, here I hope that the remaining mystery of foundations of QM and the proper meaning of feymanns path integral will be resolved.

As I understand feynmanns own words, he is not quite himeself quite content. The normalisation of the sums are something that is currently poorly regulated. This is where the energy must come in. One can not at the same time I think have infinite sums and think that the elements are distinguishable. That makes the picture of distiniguishable state totally diverge uncontrollably. I have never quite accepted the various renormalisation tricks as a satisfactory solution.

This is why the meaning of probabiltiy and these measures are so important to me. And it's unfortunate how many choose to leave this aside. Rovelli's expresses his desire to avoid this in his relational QM (which was unfortunate IMO because he starts out in an excellent manner; one of the best I've seen). It seems that some people thinkgs that asking about probablility is to ask meaningless questions, I think it means the above. to try to better understand the foundations of statistics and probability theory and how that fits to a dynamic reality as opposed to arbitrary systems of axioms.

I hope to understand more to say about the entropy-action-energy associations msyself in the future, this is one of the core things I'm working on as a hobby. I guess the "paradigm" of mine is

1) one observer - one measure-complex
2) evolution of observers - evolution of measures
3) elemetary particles ~ elementary observers ~ elementary "measure-complexes"

I originally did associated this grid, as the bones of the measure complex - which is btw the same association I maed to rovelli's spinnetworks, but I have now learned tht at least for now, it is not what those people mean.

I like these simialr ideas, but I associate these netoworks, grids or what we calle them with images of the environment living between the boundary of each possible observer.

I am open for the development of these othre ideas, to see if they ever converge into these ideas to coulpe the networkds, grids etc to observers states, and associate the interactions with the relativity of this grid.

/Fredrik

 

[Fra]

I think I'm unreadable as usual but to connect to a wider setting, I have the following association to string theory.

3) elemetary particles ~ elementary observers ~ elementary "measure-complexes"

With a modest stretch of imagination, I could see a way that this way of thinking can also connect to string theory (of course this is not how stringers thing, but it's my way of trying my best ot make sense of string theory), and then "the string" could be viewed as possibly _the_ elementary *continuum* measure-complex, but since I question the continuum my personal take on this is more like smolins talk about "string bits". If this is so, then there could be more fundamental starting point, that furthermore should shed light on the nature of these strings.

About the "background" in which the string lives, this could be seen as another measurecomplex. So rather than one measures, relating to a background, there are two measures relating to each other - giving a "background independence".

It seems many previously competing approaches are now starting to sniffing their backs, and I think that's great.

/Fredrik

 

[yuiop]

1) Is the grid detectable rather than just the effects of the grid?

2) Can absolute motion be defined relative to the grid?

3) If the answer to questions (2) and (3) is no is there any need of a grid?

Question (2) can be rephrased as "Can we determine a unique rest frame for the grid?".

In the case of the Lorentz aether the answers to questions (1) and (2) was no, so it was concluded that the answer to question (3) must be no, and the laws of physics can defined without an aether. Is the same true of the grid?

 

[marcus]

1) Is the grid detectable rather than just the effects of the grid?

2) Can absolute motion be defined relative to the grid?

Hi kev, please give me an example of something which is detectable rather than just it effects being detectable.

The answer to your question 2) according to what I read in Wilczek's book, is no. He uses terms like boost invariant. Physics, or the vacuum, is the same for different observers moving relative to each other.

It seems many previously competing approaches are now starting to sniffing their backs, and I think that's great.
...

:rofl:

Theories finding out about each other pictured as dogs meeting and getting acquainted. An earthy image, Fra. In English we don't say "back". For the rear-end of a dog we would more likely say:
rear-end
hind end
hindquarters
tail (this is an overmodest euphemism.)

All these expressions are sufficiently polite to use in mixed company, including children and old people. There are of course other expressions which I do not mention.

A horse's back is along the spine, where the saddle goes. A horse's hind end is where the tail is. It is wise to observe this distinction.

=================

Fra, I am delighted with the book! I think you would enjoy it.

 

[yuiop]

Hi kev, please give me an example of something which is detectable rather than just it effects being detectable.

The answer to your question 2) according to what I read in Wilczek's book, is no. He uses terms like boost invariant. Physics, or the vacuum, is the same for different observers moving relative to each other.

<Snipped part about dog's behinds/nether regions:P>

An example of something which is not detectable and can only be detected by its effects, is the Lorentz aether. According to Lorentz, objects moving relative to his aether, length contract and time dilate according to their motion relative to the aether (not relative to the observer).

So we observe that in fact the effects of the aether are observable. Objects moving relative to the aether do time dilate and length contract just as it says on the tin. It just so happens that the effects of motion relative to the aether conspire towards making the location or absolute rest frame of the aether undectable. In other word the Lorentz aether is boost invariant just like Wilczek's grid.

So "the effects of the the Lorentz aether are detectable but the Lorentz aether itself is not detectable" in the sense that we can not point to an absolute reference frame and say the aether is located "here".

From your answer to question (2) we can not point to an absolute reference frame and say the grid is located "here". From that point of view the grid is just as intangible as the Lorentz aether and is just a thought construct. The grid infact appears to be the Lorentz aether, with bells and whistles attached and a fancy paint job.

Now mental constructs such as additional dimensions, complex planes, parallel worlds etc can be useful in analysis and in visualising concepts even they have no tangible detectable reality.

In some theories additional dimensions have effects that are detectable even though the additional dimensions themselves are not detectable. In the "Many Worlds Interpretation" of Quantum Physics the effect of a photon splitting of into a parallel world is detectable because the split off twin photon in the parallel world interferes with the original photon and this effect is detectable. The parallel world itself on the other hand is not detectable. One advantage of the Many Worlds Interpretation is that it observer independent, unlike the Copenhagen Interpretation.

So grids and parallel worlds have effects that can be mathematically calculated and experimentally verified even if the the mental construct is not directly detectable. These constructs are helpful in constructing mental images of difficult concepts and for some people they give a clearer method of analysing given problems.

The same is true of the Lorentz aether. The predictions of aether theory are exactly the same mathematically as those of Special Relativity. Some people feel more comfortable that the length of an object is determined completely by it is motion relative to a background rather than the Special Relativity concept that the length of an object is determined by the velocity of the observer. To some people it does not seem logical that if according to one observer the length of object A is longer than that of object B and yet to another observer the length of object A is shorter than the length of object B. Of course Special Relativity is mathematically correct but so is Lorentz Aether theory and some people would find the Lorentz theory more intuitive. To give another example. The ticking rate of a clock in Lorentz theory is solely determined by its velocity relative to the aether. The clock only ticks at one rate. To other observers it may appear to tick at different rates but that is only because they are comparing it to their own clocks are also affected by their motion relative to the aether. The reson different observer see the same clock ticking at different rates is crystal clear in Lorentz aether theory. On the other hand, although Special Relativity is technically correct and indistinguishable mathematically from Lorentz aether theory, some people find the concept that the ticking rate of a clock is determined solely by the its motion relative to an observer as dificult to mentally visualise. They ask themselves "Why should a clock start ticking slower just because a distant observer starts moving relative to it?" Of course that is not the correct way to think of relativity but it certainly is not intuitive to students that are new to relativity exactly how they should think of it. The mental block comes when they try to understand how a single clock ticks at different rates simultaneously when multiple obeservers with different relative velocities are all looking at the clock at the same time. You only have to look at the endless questions about the Twin's Paradox in the Special Relativity forum to see how many people find the SR concept confusing. In fact PF could start its own Twin's Paradox sub forum! In Lorentz aether theory the Twin's paradox would barely rate a mention as it so simply solved.

So if Wilczek's grid is accepted as a valid physical concept then so should the Lorentz aether by the same logic. If the Lorentz aether is only accepted as valid if it is directly detected, then the same rules of validation should apply to Wilczek's grid.

Note: I have been careful to specify the Lorentz aether that has all the properties specifed by Lorentz and not the pre Lorentzian aether that was simply a medium for light waves to wave in and which could in principle be detected as some sort of wind. That is the straw man version of the aether.

 

[marcus]

Kev,
I get the feeling that we are not communicating. Here is what you said:

1) Is the grid detectable rather than just the effects of the grid?

Well obviously the only way we perceive things is thru their effects. So here is what I asked:

Hi kev, please give me an example of something which is detectable rather than just it effects being detectable.

I don't think you can give an example of a something, a physical entity, that is somehow ITSELF being perceived in some other way besides thru its effects.
You started talking about Lorentz aether which is not a relevant example to the question I meant to ask. Maybe I should try to say it more clearly.

What I want is an example of something which is ITSELF detectable and is not merely detectable thru its effects. I don't think you can give me an example of such a thing.

For instance the chair I am sitting on, is, as far as I can tell, only detectable by way of its effects. It holds my behind up by the Pauli exclusion principle---the net effect being an effective upwards force on my bottom.

And then there are the effects of the chair on the photons, which it happens to reflect and which then find their way into my eyes!

So your reply to me seems to miss the point. I am trying to suggest to you that as a general rule, entities are detected by their effects, and ONLY by their effects. In this sense, what Wilczek is talking about is no different from my chair. Wilczek is talking about the Vacuum of quantum field theory, which all of us know about from its well-established effects. He happens to call it the Grid, because he is writing a popular book and wants to make people take a fresh look. He has some interesting ideas about more things we can learn about the Vacuum, and will be learning (he thinks) in the next few years.
But it is still a well-established entity, quite Lorentz-invariant (although your question #2 seems to indicate you doubt this??)

Kev, I think what you need to do is READ THE BOOK if you want to discuss about the Grid. Because otherwise you may not get what is being talked about. Don't just take may words about it and spin off from there---go to the source. It just takes two days to get it from amazon---I was surprised how quick they deliver. Good luck.

 

[yuiop]

Kev,
...
I don't think you can give an example of a something, a physical entity, that is somehow ITSELF being perceived in some other way besides thru its effects.
You started talking about Lorentz aether which is not a relevant example to the question I meant to ask. Maybe I should try to say it more clearly.

What I want is an example of something which is ITSELF detectable and is not merely detectable thru its effects. I don't think you can give me an example of such a thing.

For instance the chair I am sitting on, is, as far as I can tell, only detectable by way of its effects. It holds my behind up by the Pauli exclusion principle---the net effect being an effective upwards force on my bottom.

And then there are the effects of the chair on the photons, which it happens to reflect and which then find their way into my eyes!

So your reply to me seems to miss the point. I am trying to suggest to you that as a general rule, entities are detected by their effects, and ONLY by their effects. In this sense, what Wilczek is talking about is no different from my chair.

I concede your point, but I will add that in this sense the Wilczek grid and your chair are no different from the Lorentz aether. They are all detectable by their effects.

Wilczek is talking about the Vacuum of quantum field theory, which all of us know about from its well-established effects. He happens to call it the Grid, because he is writing a popular book and wants to make people take a fresh look. He has some interesting ideas about more things we can learn about the Vacuum, and will be learning (he thinks) in the next few years.
But it is still a well-established entity, quite Lorentz-invariant (although your question #2 seems to indicate you doubt this??)

I was pretty sure the grid would be Lorentz invariant ... just like the Lorentz aether.

I am curious to know what it about the grid that qualifies it as a physical entity that does not apply to the Lorentz aether. From my point of view, history has done Lorentz a great injustice and made him out to be some sort of clown who got it it all completely wrong, when in fact quantum theory gives more and more credance to the concept of the vacuum as a physical entity rather than empty space. It is about time the scientific community acknowledged the work of Lorentz and concedes that the Lorentz aether is not just bizarre non entity as is often claimed, but is in fact the quantum vacuum. Even Einstein himself acknowledged in a speach that curved spacetime is ultimately a form of the aether. Scientist is just assumed Einstein was having a bad day when he made that speech and that he taylored the speech to please the audience he was addressing. Personally, I believe Einstein had more integrity than that.

Kev, I think what you need to do is READ THE BOOK if you want to discuss about the Grid. Because otherwise you may not get what is being talked about. Don't just take may words about it and spin off from there---go to the source. It just takes two days to get it from amazon---I was surprised how quick they deliver. Good luck.

OK, I think I will

P.S. I am not being anti-grid. I think both Wilczek AND Lorentz may have valid, useful (and possibly related) concepts.

 

[Fra]

A "reflection on Kev's reflection".

I concede your point, but I will add that in this sense the Wilczek grid and your chair are no different from the Lorentz aether. They are all detectable by their effects.

As I see it, perhaps the question kev "could have asked" - given marcus point that of course anything is "only" perceived by it's interaction properties - is wether the "mental image" of what is responsible for the interactions we do see is unique with respect to different interacting subsystems/observers?

Given that we have different interacting observers with this, do they all "by conincidence" form the same "mental image"?

Why, why not? And what consequences does each case have?

To inject my personal view here, in line with the above "ramblings", is that what I was hoping Wilczek meant with this "grid", that would make sense to me, is a kind of abstraction of a really a class of grids, and then one possible answer to the "are the mental images formed in the internal observer states unique" is no.

Then the question is of course, then where did objectivity go? Does this means thta the images are totally arbitrary? I don' think so.

Perhaps this is where the abstraction comes in. One possibility is that the "difference" in two images of this abstraction "perhaps some call it the grid" is the basis for their interactions! This means that there is no objective background abstractions on which the grid is defined. The grid could be the class of differing views, and this itself is the basis for grid-grid "interactions" which casues the grid-class to evolve relative to each other.

That's what I currently think of this. And I think it makes perfect sense. But how to get into calculations? I keep relating this grid to "relative information" or "relative states", and the rules of "information processing" could be the self-evolution of this. Here I picture a kind of relative ME principle. But the evolution an not be given a global description without observers, it means ALL evolution is relative. Here I connect to the all the different possible entropies - each when applied to an ME principle obviously giving result to different statistics and evolutions - to the observers. And here some ways of processing information will simply die out - we get evolution of observers and thus evolution of the "logic" and "measures" implicit in the ME principles. So survival is in my view all about "relative consistency".

Marcus, I'll probably order that book later. I've put it on my list, but I've another book to read first. Thanks for the clarification about identifiction of the horses back :) The scence I had in mind was the movie "dumb & dumber" where Harry hands the dogs some hotdogs with ketchup and mustard and orders the Dogs in his van to not "sniff hidies" (like he could prevent it), but I was unsure howto spell hidie. That's where back pop up. I think my english is at least "reasonable" given that I'm swedish but I regularly get words, spelling and the grammar way off chart :)

/Fredrik

 

[Fra]

> Given that we have different interacting observers with this, do they all "by conincidence" form the same "mental image"?

Of course, this still makes little since because how do they compare "mental images" if not by communication/interaction?

This is part of one of the core points of rovelli's relational QM.

IMHO, "the same mental image" would mean that the two observers can communicate their images and find themselves in agreement - ie the are not "fightning each" other like a hot and cold sink - rather than are in equilibirum, relative to their communication channel.

/Fredrik

 

[Max™]

I read somewhere in this forum (although I can not locate it right now) that Einstein was working on a concept of mass that takes the mass energy equivalence literally. The basic idea was that all mass is just a disturbance of a background energy field, or that mass is just a way that certain patterns of energy manifest themselves. Particles are not localised in the way we normally think of but are composed of energy that is spread out possibly to infinity and in this concept, what we think of as a particle is just where the enrgy is most concentrated. In effect there is no such thing as mass, just patterns of energy. Particles are much "fuzzier" than we normally think of and are smeered out over vast distances much in the way we think of a gravitational field or the curvature of space, except the particle IS the field or part of the field and particles separated by great distances are in effect superimposed on each other. One anology is to think of the rubber sheet embedding diagram. The normal visulisation is "cannon balls" resting on the rubber sheet indetting and deforming the sheet. The mass is energy visulisation does not have the cannon balls, and the particles are the indentations rather than the cause of the indentations. Sorry this all a bit vague, but I read the article a while ago and can not rememember all the details and can not track down a reference. The point is that the "mass REALLY is just a manifestation of energy" idea of Einstein's sounds a lot like the idea of Wilczek being discussed here. Can anyone here track down Einstein's original idea and compare how it similar to that of Wilczek and how it differs?

I've been working from the other direction as the traditional approach (I.E. QG projects building the universe from the bottom up looking to produce Relativity), and arrived at that same conclusion.

Only, the rubber sheet doesn't have dents in it, it has knots.

Take the sheet on your bed, stretched taut around your mattress, grab a section of it and twist it up.

The fabric around the section you're holding will be stressed and distorted.


It's interesting seeing a bottom up approach corresponding so well to the top down image suggested by Relativity.