[Draft] [Beyond series]

2’s day. So, what’s the evidence that the Standard Model is incomplete? This Symmetry Magazine article cites some examples of why physicists seek something beyond the Standard Model. Is it convincing?

• Symmetry Magazine > “Beyond the Standard Model” by Katrina Miller (02/22/2022) – The Standard Model is a quite successful best guess.

Why … are scientists so intent on discovering physics beyond the Standard Model?

“We have a precise

model of only a small sliver of reality,” Lincoln [Fermilab] says. “And there are a lot ofunexplained mysteries,” ones that can’t be understood within the Standard Model’s tried-and-truemathematical framework.[Flip Tanedo, physicist, University of California, Riverside] agrees: “A theory is

a model of nature, not a definition of what nature is,” he says.What’s more likely is that the Standard Model will be regarded as

effective at only certain scales and energies…

The unexplained mysteries (list):

- Relative lack of anti-matter found in the universe (so-called baryon asymmetry).
- No accounting for dark matter – sort of a catch-all for non-visible stuff (matter which does not interact with the electromagnetic field, related to, e.g., the puzzling rotational curves of galaxies).

As much as we would prefer to live in a simpler universe, dark matter is not the product of some astronomer’s fever dream after a late-night observing session. It’s only after decades of careful observations that cosmologists have come to the inescapable conclusion that most of the matter in our universe is simply invisible. – Paul Sutter, “The Matter with Dark Matter.”

Is there more evidence?

#### Regarding anti-matter …

To be continued …

I need to re-review the literature. To better understand reasons. And especially any cardinal assumptions.

- The reliance on symmetry arguments in the Big Bang theory.
- Connections (if any) to quantum field theory (QFT) and topological defects in spacetime.

#### Evidence for dark matter (as a new substance)

2a. Gravitational lensing.

2b. Variations (anisotropies) in the cosmic microwave background (CMB).

2c. Large-scale cosmic structures – distribution and dynamics.

…

I need to re-review the literature. To better understand reasons. And especially any cardinal assumptions.

- Connections to theories of gravity. And the need for non-baryonic matter.
- The scope and quality of data points – observational history – regarding galactic rotation curves. Generally, galactic dynamics. Past surveys, current surveys. (Especially research that some galaxies appear free of dark matter, eh)
- The impact of galactic collisions and mergers on star velocities.
- Evolution of positing “unseen matter” –> the “missing mass (and energy)” problem (or the “mass gap”) –> the much overhyped (as in popular culture) “dark matter” crisis.

In the standard Lambda-CDM model of cosmology, the total mass-energy content of the universe contains 5% ordinary [detectable] matter …

Are we actually discovering additional sources of mass (via multispectral astronomy, for example), but still falling well short of an explanation for galactic rotational curves?

Have supermassive black holes changed anything (re galactic evolution and gravitational curves)?

This article by Paul Sutter clarifies my dissatisfaction with the way gravity is treated by legacy quantum mechanics. The decoupling of quantum field interactions from space-time geometry – a non-relational model. As opposed to something more intertwined, tangled like Wilczek’s layered Grid.

So, this article (and included video) is an overview of loop quantum gravity à la Rovelli. Spin networks. As an incomplete theory.

• Space.com > “Loop quantum gravity: Does space-time come in tiny chunks?” by Paul Sutter (February 23, 2022) – What does it mean to quantize space-time?

The play is the thing – Sutter’s metaphor.

• Background independence – foreground actors and background stage.

• An interplay – a tangled drama.

He cites two key issues with loop quantum gravity. Both relate to the correspondence principle – that quantum calculations must agree with (reduce to) calculations of General / Special Relativity.

Sutter mixes the language of gravity in the usual way. In our everyday world, referring to gravity as a force; yet, in a deeper sense an interaction – of energy flux and field gradients (from which “gravity” emerges at the macroscopic level à la center of inertia).

In his video, Sutter remarks that there are variations of loop quantum gravity. In some formulations, spacetime is (merely) “pixelated” at some (defined) level. Spacetime is no longer smooth (continuous); but otherwise remains conceptually intact (in some sense).

Other formulations see spacetime as emergent. Fundamentally there’s just relationships between quantum entities, from which the geometry and “ticking” of spacetime arises.

He also talks about singularities. How the theories prevent infinite scrunching.

This article poses an interesting question; otherwise, a fashionable recap [1] of ongoing contemporary physics. For example, research on quantum gravity. And some interesting quotes by Sabine Hossenfelder.[2]

• Space.com > “Was Einstein wrong? The case against space-time theory” by Colin Stuart (Feb 28, 2022)

Moving beyond Einstein’s spacetime as a background (in some sense, a stage independent of all the interesting interactions of quantum theory) …

A. One interesting bit of research:

B. A revisit of detecting spacetime defects via distortions in the gamma ray spectrum of far, far away sources.

C. Then the same question as Paul Sutter: Is there an alternative to trying to quantize space-time? [3] And introduction of a relational theory in which interactions define spacetime:

modular space-time.Notes[1] Good grief, the article keeps using the term

particle. In an unqualified manner. I find statements like this one to be misdirections: “The quantum world is notoriously weird. Single particles can be in two places at once, for example.”Stuart even revisits Schrödinger’s cat – evading progress in our understanding of decoherence.

The “

here & there” metaphor is used so casually: “quantum physics says matter and energy exist in multiple states simultaneously — they can be both here and over there.” Which appears to conflate (classical) matter and (quantum field theory) energy. Waves indeed are extended in space vs. “here” or “there” points.Stuart contrasts the smooth continuum of spacetime with quantum superposition, despite superposition entailing linear continuity – the smoothness of the wave function. Paul Sutter does a better job of describing the real issue.[3]

[2] The Hossenfelder quotes:

So, not the metric field, of course. That is, where is the “gravitational field” in quantum field theory (QFT)? It’s not in the Standard Model. (Or Wilczek’s Core Theory, I assume.)

The real point: the quantum (QFT or tangled) structure of space-time.

[3] A recent article as well on this topic.

• Space.com > “Loop quantum gravity: Does space-time come in tiny chunks?” by Paul Sutter (February 23, 2022) – What does it mean to quantize space-time?

[4] Minic is referenced within this Wiki article on Laurent Freidel.

This podcast with Sean Carroll re the quest for quantum gravity (cf. his latest book) recaps the technical and conceptual issues, with Laplace’s demon and analogies to fluid dynamics (yeah!) in the mix.

• Quanta Magazine > “Where Do Space, Time and Gravity Come From?” by Steven Strogatz (May 4, 2022) – my summary from podcast transcript.

Gravity from Newton to EinsteinEmergenceEntanglement – “It’s not a rare, special thing.”The wavefunctionEntanglement between different pieces of the wavefunction – a relational nodal network in Hilbert spaceAdS/CFT correspondence, the holographic (so-called) principle, an analogy of “living on the boundary infinitely far away”Moving forward …