[“Models of the quantum vacuum” series]
I read this article today “‘The Unknown Question’ — The End of Spacetime” (June 22, 2019) and watched the included YouTube videos. Something bothered me which I’ve been thinking about for years, namely, that even theoretical physicist Nima Arkani-Hamed sounded like he viewed the electron as like a spherical fountain (or shower head) spewing an electric field [quantized] into the vacuum. [6]
Classically, a charged point particle generates an electric field (the Coulomb field). An electron generates a field which comes FROM the electron. Sort of like a tiny sphere perforated with countless infinitesimal “holes” FROM which emanates an electric field — adding something to the vacuum, something flowing FROM the electron. Hmm.
Feynman explored the electron as a “sphere of charge.” [5] He concluded: “Clearly, as soon as we have to put forces on the inside of the electron, the beauty of the whole idea begins to disappear. … We do not know how to make a consistent theory —- including the quantum mechanics —- which does not produce an infinity for the self-energy of an electron, or any point charge.
And Jorge Cham and Daniel Whiteson ask the question this way:
We all know that electrons have negative electric charge, but when you think about that, do you ever wonder to yourself: Where inside the electron is the charge? What is the stuff that gives it the charge, and is there room in the electron for that amount of it? Those questions seem silly because we think of charge as something a particle just has. It’s a label, and it can have lots of values: 0, −1, 2/3, etc. Try to think of mass the same way, and it will make a little bit more sense. — We Have No Idea: A Guide to the Unknown Universe
An alternative is that the electron has none of the structure (or “complex structure”) of the theories Feynman discussed. That it is not a “sphere of charge.” That we use a relational model in which “charge” is not an internal property per se. [5]
In the article’s videos, Nima Arkani-Hamed discussed how at least the “infinite energy” problem [5] in classical physics [maybe] was resolved by the cloud of virtual particles around an electron [screening] — a notion used in quantum physics for other forces besides the electromagnetic (EM) force.
I’d prefer to “flip” the perspective around. Rather than considering a point particle as a “fountain” of charge, consider an electron’s action as “biasing” [1] the quantum vacuum — inducing changes in the Grid [2]. That is, contouring its profile or gradient [3]. Symmetry is spherical in the ideal case, so the Grid is spherically stressed — field biased and vacuum polarized [4]. Grid energy density and flux are perturbed.
Metaphorically, consider a stream or pond with an outflow point in the bed or bottom. That point does not (symmetrically) pull or push water. What it does is create localized gradients in the flow of water. An object caught in those gradients is moved, as if a force is pulling / pushing it. The outflow point does not have a property of attraction (or repulsion).
The notion of charge may require a new perspective. That for all “forces,” particles of various kinds “carry” [a property of] charge. In a qualified sense, the “charge” of gravity is mass [and interacts with the metric field]. And in quantum chromodynamics (QCD) quark color is a type of charge.
For example, Jorge Cham and Daniel Whiteson write:
In the case of a particle, you can also think about gravitational mass as a gravitational charge. When two particles have electric charges, they feel electrical forces on each other, and the electrical force is proportional to the charges. In the same way, when two particles have mass, they feel a gravitational attraction proportional to their masses. Oddly enough, you can’t have negative mass, so there’s never gravitational repulsion, only attraction.” — Ibid [7]
Frank Wilczek writes:
In … QED, we can simply say that charge is the thing that photons care about.
[In QCD] The color charge of a quark creates a disturbance in the Grid — specifically, in the gluon fields — that grows with distance. It’s like a strange storm cloud that blossoms from a wispy center into an ominous thunderhead. Disturbing the fields means putting them into a state of higher energy. — The Lightness of Being: Mass, Ether, and the Unification of Forces.
So, instead of the term “charge,” let’s try another term, say, “sway.” Different particles at different energy levels with “sway” bias vacuum energy, creating gradients which may be characterized as forces — interactions (gravity, EM, weak, strong). “Sway” is a relation with the quantum Grid.
And then we also may need to revisit vacuum polarization, for the properties of virtual particle-antiparticle pairs, eh.
Other posts
• Empty Dumpty and Cosmological fact and fiction
Notes
I tend to approach quantum physics from sort of a fluid dynamics point of view.
[0] Reference: Electric charge: https://en.wikipedia.org/wiki/Electric_charge
[1] For lack of a better term — bias: to “cause … inclination … for or against … something.”
[2] Using Wilczek’s term the Grid as a space-filling medium: “The entity we perceive as empty space.”
Our deepest physical theories reveal it to be highly structured; indeed, it appears as the primary ingredient of reality.
The new theory sees a world based on a multiplicity of space-filling ethers [layers of structure], a totality I call the Grid.
I will use the word Grid for the primary world-stuff. [Layers of structure: dark energy, condensates, metric field (“that gives space-time rigidity and causes gravity”), quantum fields, “empty” space.]
In particular, the Grid is aboil with virtual particles, and these can screen or antiscreen a source. That phenomenon, for the strong force, was central to the stories that unfolded in Parts I and II. It occurs for the other forces too.
The Grid, with these aspects, is present always and everywhere. Ordinary matter is a secondary manifestation of the Grid, tracing its level of excitation.
Wilczek, Frank. The Lightness of Being. Basic Books. Kindle Edition.
And quantum field as a space-filling entity (layer) within the Grid: “… the field is there, whether or not there is a charged particle around to sense it.“
Thus fields have a life of their own. … any two electrons, anywhere in the universe, have exactly the same basic properties. Both were made by the same field! … the average values of electric and magnetic fields in deep outer space are zero, or nearly so, but the fields themselves extend throughout, and support the propagation of light rays over arbitrarily large distances.
Ibid.
[3] Where the context of the term “particle” is a localized vibration or excitation in a quantum field. And “charge” perhaps changes the quantum vacuum’s energy topology or geometry or symmetry, perturbing or ordering its [the Grid’s] “natural” randomness, in a probabilistic way, such that net effects are what we measure.
[4] And positive charge biases the quantum vacuum with a different gradient, an opposite flux.
[5] The “infinite energy” problem of a point charge was discussed by Feynman in the (pre-quark era) Lectures Volume 2 here.
There is an infinite amount of energy in the field surrounding a point charge. … The quantum effects do make some changes — the formula for the mass is modified, and Planck’s constant ℏ appears — but the answer still comes out infinite unless you cut off an integration somehow — just as we had to stop the classical integrals at r=a.
As to the mass of an electron, Feynman also said: “And there is the thrilling possibility that the mechanical piece is not there at all — that the mass is all electromagnetic.” But in pursuing that question (which turns out to be fruitless), note the charge model that he uses: “Now if we have a sphere of charge, the electrical forces are all repulsive and an electron would tend to fly apart. … The charges must be held to the sphere by some kind of rubber bands —- something that keeps the charges from flying off.”
And he concluded:
Clearly, as soon as we have to put forces on the inside of the electron, the beauty of the whole idea begins to disappear. … We do not know how to make a consistent theory —- including the quantum mechanics —- which does not produce an infinity for the self-energy of an electron, or any point charge. And at the same time, there is no satisfactory theory that describes a non-point charge. It’s an unsolved problem.
We would like now to discuss how it might be possible to modify Maxwell’s theory of electrodynamics so that the idea of an electron as a simple point charge could be maintained. Many attempts have been made, and some of the theories were even able to arrange things so that all the electron mass was electromagnetic. But all of these theories have died.
Anyway, an alternative is that the electron has none of the structure (or “complex structure”) of the theories Feynman discussed. That it is not a “sphere of charge.” That we use a relational model in which “charge” is not an internal property per se.
Here’s what Lee Smolin says about a relational model:
I believe that Leibniz’s insight of a world that optimizes variety, subject to “the greatest order possible”, is a powerful concept … I believe we ought to see variety as a measure of complexity which applies to systems of relationships. These are systems of individual units, which each have a unique set of interactions or relationships with the other units in the system. … In a Leibnizian world, an object’s properties are not intrinsic to it — rather they reflect the relationships or interactions that object has with other objects. — 2017 : WHAT SCIENTIFIC TERM OR CONCEPT OUGHT TO BE MORE WIDELY KNOWN? (Jun 27, 2019)
[6] Here’s how Nima Arkani-Hamed discussed the “infinite energy” problem in the article’s video:
For instance in the early part of the last century physicists were very confused by the fact that if you took the electron (and the electron they didn’t think had any size) [then] well, the electron is surrounded by an electric field [and] that electric field carries energy in it, and if you look at the energy in that electric field that appears to be infinite, and so the electron would by equals mc-squared, the electron should have an infinite mass, which it certainly didn’t have. One possibility is … that appears to be a colossal fine-tuning, but there was an explanation which in fact the people in the early part of the century couldn’t have known, but that in fact as you get closer and closer to the electron because of quantum mechanics, you start seeing that it’s actually surrounded by a cloud of virtual electrons and anti-electrons okay, and that cloud invalidates this computation that tells you there’s an infinite amount of energy. In fact when we take the cloud into account, the infinity largely goes away, and you don’t have the same problem. Okay so in that case one could have made a prediction that something should happen at a specific distance away at some specific distance scale that cuts off this problem and indeed it did. It was quantum mechanics and positrons (anti-electrons) and so that’s what worked.
[7] Jorge Cham and Daniel Whiteson also say it this way:
Gravity is sort of the same way, but not quite. You can think of mass as the “gravity charge” of a particle that determines how much gravity it feels. But there is no “negative” mass. Gravity doesn’t repel particles with mass. This is important because it means that gravity can’t be canceled out. This is what happens to the electromagnetic force at large scales.
[8] Quantum fluctuations visualization
[9] Visualizations of Quantum Chromodynamics by Derek Leinweber, Professor of Physics, Department of Physics, School of Physical Sciences, University of Adelaide.
My explorations of QCD-vacuum structure [were] featured in Professor Wilczek’s 2004 Physics Nobel Prize Lecture.
Searching online regarding some questions (below) about charge found a variety of ideas and even some theories. Here’re some examples.
An undated paper [https://arxiv.org/pdf/physics/0010050.pdf] with references from the 1990’s describes a concept of Condensed Electromagnetic Radiation (“individual electromagnetic wave units are squeezed into a closely packed wave packet”). The degree of polarization of CER particles explains their various charges. “This identification will also explain the charge unit of the electron and the positron as corresponding to the maximum polarization possible.”
An article on the Boston University Physics site states: “Comparing these two forces, it is clear that the charge in electrostatics plays a similar role to that of the mass in gravity. A major difference is that while the gravitational force is always attractive, the electrostatic force can be either attractive or repulsive.”
And there’s some speculation that “dark energy [negative energy density] could be a repulsive gravitational force that only acts over large scales.”
There also are threads on physics.stackexchange and Quora.
1. https://physics.stackexchange.com/questions/224254/why-doesnt-gravity-have-charges
2. https://www.quora.com/Is-mass-the-charge-of-gravity
3. https://www.quora.com/Why-is-gravitational-force-always-attractive-in-nature
Another post [2018] in this thread includes an entensive excerpt from A Grand Unification Theory — a theory of the vacuum in line with many aspects of the loop quantum gravity theory (granular, discrete space — “an extremely fine fabric or network ‘woven’ of finite loops”) and Einstein’s field equations (stress–energy tensor). Key postulates: strings of energy, singularities (with characteristics such as “absolute unit of time”). Other terms: quantum spinning loops (spinors), supersymmetry, helicity, coupling.
Curious about models of the quantum vacuum? Here’s a 2008 NBC News article on “the Grid” — The Grid we live in (September 24, 2008).
And here’s a link to a paper (PDF) by Wilczek for the MIT Physics Annual 2009, “What is Space?” The paper is a useful recap of the history of space — so-called empty space, the void, the plenum, ether; and ends with a brief overview of a toy model of quantum reality.
And as to the interplay of “charge” and field for all the forces …
My guess at a table …
Wiki: The weak interaction does not produce bound states nor does it involve binding energy – something that gravity does on an astronomical scale, that the electromagnetic force does at the atomic level, and that the strong nuclear force does inside nuclei.
Wiki: At high energy the weak force and electromagnetic force are unified as a single electroweak force.
References:
Wiki: Charge (physics)
Wiki: Special unitary group – The group of unitary matrices with determinant 1.
Wiki: Unitary group – More general unitary matrices may have complex determinants with absolute value 1, rather than real 1 in the special case.
Thanksci: Gauge Symmetries
“Charges of various kinds are always carried by fields which are complex.” – Leonard Susskind, New Revolutions in Particle Physics: The Standard Model Lecture 7, Stanford, YouTube (2010).
James Owen Weatherall provides a historical overview of the “physics of nothing” in his book “Void: The Strange Physics of Nothing (Foundational Questions in Science).”
I found these remarks by science communicator and Forbes contributor Ethan Siegel interesting, in his Forbes article, “Ask Ethan: Are Quantum Fields Real?” (Nov 17, 2018), which contains some useful visuals.
Physicist Chad Orzel is one of my favorite science communicators. And since the interplay between “particles” in quantum field theory and the quantum vacuum (aka “space”) is one of my favorite topics, his latest Forbes article caught my attention. As well as his unpacking the question with levels of understanding.
Forbes > “How Strong Is Space?” by Chad Orzel, Science Contributor (Associate Professor in the Department of Physics and Astronomy at Union College).
This 2019 proposal aligns with my post regarding eliciting (exciting) energy effects from the quantum vacuum, which otherwise is bland on large scales. And the notion that “the Grid is aboil with virtual particles” (Wilczek). And the “soup” of proton structure – more than quarks and gluons.
• Phys.org > “‘Quantum Foam’ Scrubs Away Gigantic Cosmic Energy” by David Lindley (September 27, 2019) – Physicist at University of California, Davis, proposes that empty space is filled with enormous energy, but this energy may be hidden because its effects cancel at the tiniest scales – empty space resembles a zero-energy vacuum on large scales.[1]
Notes
[1] As Paul Sutter wrote: