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CATEGORY: Questioning the Foundations Essay Contest (2012) [back]
TOPIC: Not on but of. by Olaf Dreyer [refresh]
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Author Olaf Dreyer wrote on Sep. 4, 2012 @ 11:15 GMT
Essay Abstract

In physics we encounter particles in one of two ways. Either as fundamental constituents of the theory or as emergent excitations. These two ways differ by how the particle relates to the background. It either sits \emph{on} the background, or it is an excitation \emph{of} the background. We argue that by choosing the former to construct our fundamental theories we have made a costly mistake. Instead we should think of particles as excitations of a background. We show that this point of view sheds new light on the cosmological constant problem and even leads to observable consequences by giving a natural explanation for the appearance of MOND-like behavior. In this context it also becomes clear why there are numerical coincidences between the MOND acceleration parameter $a_0$, the cosmological constant $\Lambda$ and the Hubble parameter $H_0$.

Author Bio

Olaf Dreyer is a theoretical physicist working at the university in Rome. He received a PhD in Quantum Gravity at the Pennsylvania State University and has worked at the Perimeter Institute, Imperial College, and the MIT, where he was supported by a fqxi grant.

Download Essay PDF File

Yuri Danoyan wrote on Sep. 4, 2012 @ 15:52 GMT
Dear Olaf

Are you agree with my abstract?

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Author Olaf Dreyer replied on Sep. 10, 2012 @ 14:23 GMT
Dear Yuri:

Thanks for the interest in my article. In your article you mention these four assumptions that need changing:

1. 4D spacetime.

2. Gravity as a fundamental force.

3. 3 fundamental dimensional constants(G,c,h).

At this level of discussion I would agree with all of them. In my view the 4D spacetime is only an emergent object and not fundamental, gravity is emergent, and because of that the gravitational constant G can not be of fundamental importance. In fact I provide a formula for G in my essay. The devil is of course in the details.

I particular like the last sentence of your essay:

"I would really wish to those who are working in the field of fundamental physics problem to not remain unemployed."

Michael Silberstein wrote on Sep. 6, 2012 @ 04:54 GMT
Hi Olaf,

We are defending something very similar. Check out our essay and the attached pubs. Comments gratefully received!

attachments: 1_FINAL_02649381_29_5_055015.pdf, 1_Stuckey.pdf

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Sergey G Fedosin wrote on Sep. 9, 2012 @ 06:41 GMT
Dear Olaf,

I do not agree with you that matter is simply is excitation of the background. The matter is particles which compose substance of bodies. The field is originated by particles of matter at the low levels of matter, and the field holds the form of particles. The excitation is a consequence of interaction of ensembles of particles. It may be a wave or a quantum such as photon. Such...

view entire post

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Olaf Dreyer replied on Sep. 24, 2012 @ 12:30 GMT
Dear Sergey:

Thank you for your interest in my essay. I was trying to understand what your theory says about the cosmological constant but I could not quite understand it. It seemed to me that the cosmological constant is not really constraint in your framework.



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Gary Simpson wrote on Sep. 18, 2012 @ 23:52 GMT
A pretty good read ... Is there any difference between particles being an excitation of the background - as you describe - and an aether medium?

Interpreting gravity as a form of Casmir force is clever.

You might be interested in the work of Milo Wolff. He is an advocate of a wave media for both forces and particles.


Gary Simpson

Houston, Tx

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Olaf Dreyer replied on Sep. 19, 2012 @ 13:29 GMT
Dear Gary:

Thank you for your comments.

There is an interesting difference between what I am proposing and the old style aether theories. In the old theories the aether was a physical medium that was everywhere and it carried the electromagnetic field. Matter on the other hand was not an excitation of the aether. Matter was to aether what boats are to water. This is the crucial difference to what I am saying. In my thinking both fields and matter are both excitations.

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Gary Simpson replied on Sep. 19, 2012 @ 22:12 GMT
Yep ... you would like Dr Wolff's work. He solved the spherical wave equation ~25 years ago and concluded that it constitutes an extended spatial structure. He interprets it as the electron and positron.


Gary Simpson

Houston, Tx

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Hoang cao Hai wrote on Sep. 19, 2012 @ 16:02 GMT

Very interesting to see your essay.

Perhaps all of us are convinced that: the choice of yourself is right!That of course is reasonable.

So may be we should work together to let's the consider clearly defined for the basis foundations theoretical as the most challenging with intellectual of all of us.

Why we do not try to start with a real challenge is very close and are the focus of interest of the human science: it is a matter of mass and grain Higg boson of the standard model.

Knowledge and belief reasoning of you will to express an opinion on this matter:

You have think that: the Mass is the expression of the impact force to material - so no impact force, we do not feel the Higg boson - similar to the case of no weight outside the Earth's atmosphere.

Does there need to be a particle with mass for everything have volume? If so, then why the mass of everything change when moving from the Earth to the Moon? Higg boson is lighter by the Moon's gravity is weaker than of Earth?

The LHC particle accelerator used to "Smashed" until "Ejected" Higg boson, but why only when the "Smashed" can see it,and when off then not see it ?

Can be "locked" Higg particles? so when "released" if we do not force to it by any the Force, how to know that it is "out" or not?

You are should be boldly to give a definition of weight that you think is right for us to enjoy, or oppose my opinion.

Because in the process of research, the value of "failure" or "success" is the similar with science. The purpose of a correct theory be must is without any a wrong point ?

Glad to see from you comments soon,because still have too many of the same problems.

Regards !


August 23, 2012 - 11:51 GMT on this essay contest.

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Member Giacomo Mauro D\'Ariano wrote on Sep. 20, 2012 @ 10:40 GMT
Dear Olaf

I've read your essay with great interest. It is really intriguing, and presents relly fresh new original ideas, very promising. I'm very interested in Modified Newton Dynamics (MOND), since I think that from a new approach to quantum gravity we may get some modification of the gravity law, which is beyond the sensitivity of available experiments. I'd love to discuss more with you about.

For the moment I've just a stupid simple question about your essay (which shows that I've not really understood some technical part).

Eq. (10) seems to have a dependence of G with the gravitational mass of the object (since a is the radius). I looked everywhere for the meaning of m, but also in your previous paper "Internal relativity" I found the same. Am I understanding right? Shouldn't be G a universal constant?

My best to you

and compliments again


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Olaf Dreyer replied on Sep. 20, 2012 @ 10:44 GMT
Dear Mauro:

Thank you so much for the kind words!

The dependence of G on m is a true issue. Let me explain how I think about that:

A similar issue arises with the speed of light c. In generic solid state models the speed of an excitation will depend on the particle species. There are exceptions though. In Volovik's models that rely on a Fermi point all excitations have the same speed that is given by the shape of the Fermi surface near the Fermi point.

I think that the situation is similar with G. Generically G depends on the species but there are models where G will be the same for all species. This does not require that all particles have the same mass because it is the quotient of m and the radius r that is important. What is needed is thus that the mass and the radius scale in the same way. Intriguingly this is exactly what happens for a Schwarzschild black hole (r = 2m).

One should also note that in an emergent theory one does not have the freedom to add emergent particles at will. One can change the underlying theory at will but because the process of emergence is non-trivial it is not immediately clear what the emergent theory will be like. It is hence not that trivial to create a theory that has particle species with arbitrary mass to radius quotients.

Thanks again for the interest.

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James Lee Hoover wrote on Sep. 20, 2012 @ 22:05 GMT

"The spin-wave above is an excitation of the background not an excitation on the background.

Gravity appears because the ground state θ depends on the matter. The picture of gravity that we have given in the last section is valid only for zero temperature."

Do most physicists subscribe to the "of" position, for example Lawrence Krauss in his new book? My essay deals with gravity and the possibility of cancelling it. I'm not sure how your "of" position would affect it. Any thoughts?


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Olaf Dreyer replied on Sep. 24, 2012 @ 12:50 GMT
Dear Jim:

Thanks for having a look at my essay!

I think it depends who you ask. There are basically two schools here. The first school consists of elementary particle physicists and they subscribe completely to the "on" position. Usual quantum field theory is a theory of fields on spacetime. The other school consists of solid state physicists. For them the "of" picture is very natural because that is how they encounter particles; as quasi-particles. I am not sure which school is larger. There are a lot of elementary particle physicists but there might just be more solid state physicists.

If one takes the "of" point of view then there is still the question of how gravity arises. It could either be a an emergent excitation (the graviton) or it is a non-perturbative effect. It is this second possibility that I am suggesting.

I am not sure about canceling gravity. I think in my model gravity would always be attractive. I am going to have to look at your essay.



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Member Benjamin F. Dribus wrote on Sep. 21, 2012 @ 09:47 GMT
Dear Olaf,

This is a very interesting set of ideas you are proposing. I particularly appreciate your identification of the "cosmological constant problem" as an artifact of background dependence. I have a few questions:

1. What are the implications for the microstructure of "spacetime?" If one assumes that matter-energy is a way of talking about "spacetime" excitations, then it seems "spacetime" might be very nonmanifold-like at small scales.

2. As you know, many of the properties of "elementary particles" in quantum field theory are determined by the representation theory of the Poincare group of symmetries of Minkowski spacetime. Even in GR, this is a priori problematic because the spacetime will interact with the matter energy it "contains," thereby complicating the use of spacetime properties to determine particle properties. When you go a step further and view particles as part of spacetime rather than just interacting with it, this seems to deepen the problem further. What type of constraints would one use to replace the Poincare symmetries in this general context?

3. The only "respectable" approach to quantum gravity I know of that claims to solve the "cosmological constant problem" is Sorkin's causal sets. What do you think about this "solution?"

Thanks for the interesting and informative submission! Take care,

Ben Dribus

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Olaf Dreyer replied on Sep. 24, 2012 @ 13:29 GMT
Dear Ben:

Thanks for the interest in my essay! Here are my replies to your questions:

1. The micro-structure of spacetime would definitely not be manifold-like. The smoothness of the spacetime would only arise in the large scale/low energy limit. A smooth spacetime would be to the fundamental micro-description as the surface of water to water molecules.

2. The argument...

view entire post

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Steve Weinstein wrote on Sep. 23, 2012 @ 00:58 GMT
Hi Olaf,

In the late '50s and early '60s, Wheeler also pursued the idea that matter is an excitation of the background space-time in his "geometrodynamics" program. Are their points of contact between his research program and yours?


PS: Check out my essay, if you like:

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Olaf Dreyer replied on Sep. 24, 2012 @ 13:39 GMT

Thanks for having a look at my essay.

I think Wheeler tried to see if the bound states of pure gravity (he called them geons) could play the role of elementary particles. This would be a very economic way of organizing the world. All that is needed is the gravitational field. My program is very similar in spirit but I do not start with the gravitational field. Instead I allow for more general kind of backgrounds. This makes the emergence of particles much easier (I do not have to construct a geon) but the emergence of gravity itself is now much harder.

Hope to see you around sometime soon!

Now on to your essay...



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Yuri Danoyan wrote on Sep. 25, 2012 @ 11:02 GMT
See my discussion with George Ellis

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Author Olaf Dreyer replied on Sep. 25, 2012 @ 11:19 GMT
Dear Yuri:

I just had a look at the discussion. Unfortunately it seems somewhat inconclusive. You do not seem to want to supply the details that G. Ellis is asking for. Are you working on a longer reply?



Yuri Danoyan replied on Sep. 25, 2012 @ 11:24 GMT
Just waiting George answer...

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Member Sean Gryb wrote on Sep. 25, 2012 @ 15:30 GMT
Hey Olaf,

Hope things are well!

I really enjoyed reading your essay, especially the simple model you use to get the MOND-like behaviour. Indeed, this model is a lot simpler than some of the other entropic gravity approaches. Very cute indeed! Flavio and I give a simple toy model, based on shape space, in our essay that gives a holographic behaviour. I wonder if there could be any connections between your particle models and shape space?

There is one thing that confuses me though. Can't the cosmological constant problem be stated without any reference to matter? If you just look at free gravity and use dimensional arguments then the cosmological constant should have dimensions of mass squared. But then the *dimensionless* cosmological constant has to be massively fine tuned to agree with the measured value. So the fine tuning problem is already in free gravity. Right?



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Author Olaf Dreyer replied on Sep. 26, 2012 @ 14:55 GMT
Hi Sean:

Thanks for the interest!

I am going to have a look at your model. Very curious to see how you are getting the holographic behavior. In connection with that there is a question that I always wanted to ask you: Do you know this paper by Milgrom?

The Mond Limit from Spacetime Scale Invariance

The Astrophysical Journal vol. 698 (2) pp. 1630

Is there a connection between your work on gravity and this? I am asking because both of you stress scale invariance. Have you looked at that?

Your statement about the cosmological constant is correct. In an effective quantum field theory view of gravity your argument leads to a problem without the introduction of matter. A problem I have with that view is that you have to rely on a theory (pert. quantum gravity) that we know has problems. In the argument involving matter the only thing you need to know about gravity is that it reacts to the presence of energy. You don't even need to know anything about quantum gravity.

It is also true of course that the cosmological constant problem without matter does not make the cosmological constant problem with matter go away. If you think of matter as sitting on spacetime the problem is there.

Now on to your essay ...



Member Sean Gryb replied on Sep. 26, 2012 @ 16:17 GMT
Hi Olaf,

I know about Milgrom's result but I have not seriously looked at the consequences for SD. I had one crazy idea recently (if you'll allow me to indulge ;-). The conformal group in 3d is SO(4,1), which is the isometry group for de Sitter. Thus, I think a natural action for SD is the one of Stelle and West that uses an SO(4,1) connection because it can be decomposed into a conformal geometry in 3d.

Now, how do you couple fermions to this action? You can't use normal spinors because the space is locally de Sitter NOT locally Minkowski. Thus, you shouldn't use spin 1/2 reps of the Poincarre group but rather spin 1/2 reps of the de Sitter group (which, is isomorphic to the conformal group). But, because the cosmological constant is small, these "dS spinors" should be effectively the same as standard spinors, at least for particle physics experiments. You would only notice a difference in the dynamics at cosmological scales related to the cosmological constant (because this is what distinguishes the dS group from Poincare). But the MOND scale is the cosmological scale! So maybe you would expect MOND like behavior from the SO(4,1) spinors?? And maybe the relation to scale invariance is because of the isomorphism with the conformal group??

I don't know... but I'd like to look into this at some point! Did that make sense??

I take you're point about the cosmological constant problem. You're right that the story might change once we have a good theory of quantum gravity. Now I understand your point. Thanks!



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Author Olaf Dreyer replied on Oct. 1, 2012 @ 21:32 GMT
Hi Sean:

I like the idea! I will have a closer look. I guess the meat lies in the transition

SO(4,1) --- \Lambda ->0 ---> SO(3,1)

How do the spinors change?

More later ...



qsa wrote on Oct. 1, 2012 @ 00:20 GMT
Dear Olaf,

It has a while since I heard anything new about you. While I admit I liked your older work more still good to see you back. I hope you check out what I have done maybe it will give you an idea. Sorry for doing copy and paste from my other posts but it should be enough to give you an idea.

In my theory everything is emergent all from a...

view entire post

attachments: 5_newqsa.pdf

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Sergey G Fedosin wrote on Oct. 2, 2012 @ 07:45 GMT
After studying about 250 essays in this contest, I realize now, how can I assess the level of each submitted work. Accordingly, I rated some essays, including yours.

Cood luck.

Sergey Fedosin

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Author Olaf Dreyer wrote on Oct. 2, 2012 @ 08:01 GMT
Dear Sergey:

You read 250 essay! That is very impressive.

Thank you for the consideration and the vote.



Yuri Danoyan wrote on Oct. 4, 2012 @ 00:00 GMT
Dear Olaf

Don't forget please impartially evaluate my essay

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Roger Granet wrote on Oct. 4, 2012 @ 03:13 GMT
Dr. Dreyer,

Hi. As with many of the more mathematical essays here, I can't say I understood all of your paper because I'm a biochemist and not a physicist or mathematician, but I can say that based on my own thinking, what you're saying makes a lot of sense, and I will give you a high rating with my vote. I would further add that just about everything, including matter and energy and...

view entire post

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Paul Reed replied on Oct. 8, 2012 @ 10:57 GMT

Roger Granet brought my attention to your essay, so here are some comments on it:

“Particles are either fundamental or they are emergent. If they are fundamental they are sitting on a background; if they are emergent they are excitations of a background”

Physical existence (as known to us, which is all there is unless one enters the domain of belief) must comprise...

view entire post

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Author Olaf Dreyer replied on Oct. 8, 2012 @ 12:56 GMT
Dear Roger & Paul:

Many thanks for the interest in my essay!

Let me try to give an answer to your questions. I think there is an important point to be made here that concerns the notion of emergence. To make thing clear let me start with an example: an ice cube. The frozen ice consists of water molecules that are arrayed in a very regular lattice. This lattice can vibrate and because we are dealing with a quantum system there exists a smallest unit for each of the vibrational modes. These are the phonons. In this example it is clear that the water molecules are more fundamental than the phonons. The phonons are just quantized vibrational modes of the lattice of water molecules.

But now imagine how this situation would look to an observer made up from these phonons (this is a bit of a stretch because phonons are too simple to make up an observer but there are more interesting models of this kind that can do this). This observer would consider these phonons as the elementary particles of her world. The phonons would be like the light in our world.

What I am proposing is that our elementary particles (electrons, quarks, light, etc.) are of this kind: they are the excitations of an unknown substance just like phonons are the excitations of the lattice of water molecules.

Paul makes the statement:

"Either something has physical presence or it does not."

Here we have an example that doesn't quite fit into this dichotomy. The phonons have existence but if you melt the ice cube the lattice disappears and with it the phonons.

I hope this helps.



Paul Reed replied on Oct. 9, 2012 @ 09:06 GMT

Thanks for your reply, it is good to come across someone who responds with a constructive statement, rather than, in effect, no it is not. Now I must just stress that I have no background, so I can only address the topic in terms of generic logic.

So, starting with a sentence towards the end of the post: “The phonons have existence but if you melt the ice cube the lattice...

view entire post

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Sergey G Fedosin wrote on Oct. 4, 2012 @ 04:51 GMT
If you do not understand why your rating dropped down. As I found ratings in the contest are calculated in the next way. Suppose your rating is
was the quantity of people which gave you ratings. Then you have
of points. After it anyone give you
of points so you have
of points and
is the common quantity of the people which gave you ratings. At the same time you will have
of points. From here, if you want to be R2 > R1 there must be:
In other words if you want to increase rating of anyone you must give him more points
then the participant`s rating
was at the moment you rated him. From here it is seen that in the contest are special rules for ratings. And from here there are misunderstanding of some participants what is happened with their ratings. Moreover since community ratings are hided some participants do not sure how increase ratings of others and gives them maximum 10 points. But in the case the scale from 1 to 10 of points do not work, and some essays are overestimated and some essays are drop down. In my opinion it is a bad problem with this Contest rating process. I hope the FQXI community will change the rating process.

Sergey Fedosin

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Conserned Public wrote on Oct. 6, 2012 @ 08:34 GMT
Sergey G Fedosin is bombing entrants' boards with the same "why your rating has dropped" message. They are all dated Oct. 4... same message.

WTH? I've seen one fine essay drop 89 (eighty-nine) positions, in "Community Rating" in the past 24 hours, and “Sergey’s note” came BEFORE it plummeted. Hmm.

The vote/scaling of this contest is quite nebulous.

"Hackers Rule!", I suppose!

Well??? What else is one to think? The General Public is... Watching…

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Jayakar Johnson Joseph wrote on Oct. 23, 2012 @ 04:10 GMT
Dear Olaf Dreyer,

In Coherently-cyclic cluster-matter paradigm of universe, the Galaxy rotation problem described with MOND is expressional differently by eigen-rotational string quanta of galaxies in the holarchy of universe, in that gravity emerges as a tensor product of eigen-rotational strings.

In this paradigm angular acceleration of each eigen-rotational string is analogue of emergent excitations, whereas its inertial angular velocity is fundamental and thus the segmental dynamics of the universe in homeomorphism is expressional as the background of the universe.

With best wishes


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Kamilla Kamilla wrote on Apr. 10, 2016 @ 17:23 GMT
That was an really impressive post and i like that. ip address

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