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This article (below) is about **classical analogs of quantum models**. It uses an unqualified characterization of electrons as “microscopic particles.” With derivative wave-like phenomena.

An electron, which is a particle that moves in an atom or in a solid, may have properties that give rise to wave-like phenomena.

While applauding **visualization**, I continue to sort of cringe when somewhat technical articles use a legacy “particle” framing. Although perhaps (without any mention) using the term as a metaphorical handle for something really weird – so unlike our everyday (macroscopic) experience, there’s no mention of a mainstream perspective which helps clarify classical tropes. Namely quantum field theory (QFT) – a perspective where “*there are no particles, there are only fields*.”

“Fields” are indeed harder to connect with our everyday experience and language for describing stuff. So, typically there’s even no use of the term *field*.

But this article (and the research paper itself) does get into discussing “*waves of electrons*” (modeled by waves that propagate freely along a one-dimensional array of coupled pendulums) and the *wavefunction* (Schrödinger’s equation). Yet only an *effective* analysis modeling quantum MECHANICAL dynamics (phenomena), not field theory.

• Phys.org > “Classifying quantum secrets: Pendulum experiment reveals insights into topological materials” by Tel-Aviv University (March 7, 2024) – A large mechanical system that operates under dynamical rules – *analogous to those found in quantum systems* – allows researchers to **visualize** (model) phenomena occurring in specialized “topological” materials through the movement of coupled pendulums.

**Objective**

Classical mechanical realizations of solid-state effects, as a way to to quantitatively explore similarities and the differences between quantum and classical topological effects.

**Terms**

• Zener tunneling (“as the splitting of a wave”), Zener tunneling probability (between nearby energy bands)

This splitting, and specifically its connection to the motion of the wave in either direction, is a clear characteristic of the Schrödinger equation.

• Wave evolution in a topological medium

]]>Long-term space missions pose long-term mental health issues.

• Space.com > “Watch trailer for ‘Space: The Longest Goodbye,’ new film exploring **astronaut mental health** (video)” by Jeff Spry (February 18, 2024) – Follow a NASA psychologist as he trains future deep-space travelers to maintain [mental] stability on long missions.

• YouTube > Greenwich Entertainment > “Space: The Longest Goodbye | Official Trailer” (Jan 12, 2024) – In the next decade, **NASA will send astronauts to Mars** for the first time. Separated from Earth, and unable to communicate with ground in real time, **crew members will experience extreme isolation** that could gravely affect their three-year journey. This Sundance-premiering documentary follows a savvy **NASA psychologist** tasked with protecting daring space explorers.

The immune system, hippocampus, neurotransmitter system, stress management, … the microbiota gut-brain axis. This article even mentions the film The Martian.

• Space.com > “Space travel taxes astronauts’ brains. But microbes on the menu could help in unexpected ways” by Felice Jacka, Dorit Donoviel [1] (Jan 30, 2024) [originally published at The Conversation] [includes YouTube video on our microbiome] – Diet is important for astronauts’ mental and cognitive health.

Diet quality is consistently and independently linked to the risk of depression or anxiety. Clinical trials show improving diet quality can lead to profound improvements in depression and anxiety symptoms.

Diet also affects the size and function of a specific brain region – the hippocampus – that is crucial to learning and memory, as well as for maintaining mental health. When even young healthy adults eat “junk” foods, aspects of cognition linked to the hippocampus quickly decline.

On the other hand, research shows a diet containing more and varied plant foods and seafood … leads to better cognitive performance. This study was conducted in a closed chamber for 45 days, designed to mimic conditions in space.

So ensuring all astronauts have the healthiest and most diverse of microbes for the whole of the mission is vital.

**Notes**

[1] Felice Jacka is the founder and director of the **Food & Mood Centre** at Deakin University and the founder of the International Society for Nutritional Psychiatry Research (ISNPR).

Dorit Donoviel is Executive Director, NASA-Funded **Translational (moving products from lab-bench to practice) Research Institute for Space Health** at Baylor College of Medicine.

[video thumbnail caption]

As noted in my June 8, 2022, comment above, this recent APOD cites the famous Illustris Simulation, which exhausted 20 million CPU hours in 2014.

• APOD > “Illustris: A Simulation of the Universe” (Dec 31, 2023) > YouTube > Illustris Simulation (May 11, 2014)

]]>(caption)

Illustris: A Simulation of the UniverseVideo Credit: Illustris Collaboration, NASA, PRACE, XSEDE, MIT, Harvard CfA

Music: The Poisoned Princess (Media Right Productions)

Explanation: How did we get here? Click play, sit back, and watch.

A computer simulation of the evolution of the universe provides insight into how galaxies formed and perspectives into humanity’s place in the universe.

The Illustris project exhausted 20 million CPU hours in 2014 following 12 billion resolution elements spanning a cube 35 million light years on a side as it evolved over 13 billion years.The simulation tracks matter into the formation of a wide variety of galaxy types. As the virtual universe evolves, some of the matter expanding with the universe soon gravitationally condenses to form filaments, galaxies, and clusters of galaxies.

The featured video takes the perspective of a virtual camera circling part of this changing universe, first showing the evolution of dark matter, then hydrogen gas coded by temperature (0:45), then heavy elements such as helium and carbon (1:30), and then back to dark matter (2:07).

On the lower left the time since the Big Bang is listed, while on the lower right the type of matter being shown is listed.

Explosions (0:50) depict galaxy-center supermassive black holes expelling bubbles of hot gas.

Interesting discrepancies between Illustris and the real universe have been studied, including why the simulation produced an overabundance of old stars.

Illustration by Koji Arai, Caltech

Thinking like a physicist … When is a burger like a layered stack of spheres? Thinking in 3D and spherical coordinates.

• Caltech Magazine > Fall 2023 > “Building a Burger with Math” by Whitney Clavin (December 13, 2023) – Physicist Koji Arai created a digital burger portrait using just one complex mathematical function.

]]>The basic idea is that all the layers of a typical burger – the bun, onion, tomato, cheese, patty, and lettuce – can be described, or mapped out, using a

single mathematical formula, also known as the “Generalized Burger Function.” Each layer is essentially a sphere; the different variables of the equation dictatehow each sphere should be squeezed or deformed to resemble the burger ingredients.The instinct to simplify, Arai says, is one most physicists can understand. “It’s the physicist’s dream to create

simple models of things,” he says. “Take a cow for instance. To a physicist, it’s simply a sphere.“

Forget visualizations of “particles,” no matter how small, moving apart from some medium.

This article by Paul Sutter … got me imagining a **4D wave function** of interacting fields and wavepackets … interfere, constructively and not … so that **dynamic bendiness is innate in 4 dimensions** … because **we’re talking about waves from which wave dynamics emerge** …

“‘Straight’ only in the sense that every step forward is always placed directly in front of the previous.”

“Mass and energy bend the shape of spacetime” – rather spacetime energy dynamics have topology.

“Bending of spacetime [affects] the paths and motions of everything else” – rather wave interactions follow **the principle of least action.**

• Phys.org > “How to think about a four-dimensional universe” by Paul M. Sutter, Universe Today (November 13, 2023)

]]>Spacetime is not a fixed stage, but

a flexible membranethat suffuses the entirety of existence. It is a thing, an object and entity in its own right, a dynamical actor in the cast of characters in the universe. The universe consists of the usual assortment of particles and radiation and all their wonderful interactions, and those interactions don’t happen on top of spacetime but along with spacetime, which has now joined their ranks.

Antigravity?

Regarding a “*force-less*” physics and the notion of gravitational “charge,” if gravity really is about spacetime geometry (topology), is an “anti” (repulsive) geometry possible?

I really can’t visualize 4D (or higher) geometry anyway.

And anti-matter (as noted in this post) is not the answer.

Bring on the fluid dynamics analogies …

[Image: “the [2D] bowling ball on a bedsheet” analogy – a “down” gravity well.]

[Animation: A better analaogy – space [spacetime] as a three-dimensional grid. … where all the lines are mutually perpendicular in all three dimensions, … a grid where lines get “sucked” inward by the presence of masses.]

• Big Think > “Ask Ethan: Why is there no antigravity?” by Ethan Siegel (December 1, 2023) – You might imagine that spacetime could “curve” in an “anti” fashion, resulting in antigravity; but …

]]>So why doesn’t the electric force dominate the Universe, instead of the gravitational force? … The answer is that

the Universe is electrically neutral, where the amount of positive charge and the amount of negative charge balance out.The other two (nuclear) forces are also prohibited from affecting large scales.

The reason the gravitational force is so important — arguably, the only important force on extremely

large cosmic scales— is because even though it’s so tiny, it’scumulative[and so modeled according to the “center of mass-energy” concept].

But we could have imagined a very different Universe: one where either negative mass or negative energy states could exist. … Instead of starting with empty space, imagine that space is uniformly filled with matter: like a massive, perfect fluid [with a certain density]. [And “particles” with higher / lower densities than the containing fluid.]If you have a helium balloon floating in your car and slam on the brakes, all the passengers will jerk forward, but the balloon will float to the back. … because the (denser, heavier) air in the car “remains in motion” more strongly than [and relative to] the (less dense, lighter) helium balloon.

Regarding my theme of what’s changed in the last 50 – 100 years in mathematical physics …

**Modeling the profile of spacetime**: A question of the scalar curvature of three-dimensional spaces with steadily decreasing amounts and concentrations of energy-mass.

**Thinking like a physicist**, what details can be ignored? Quantifying flatness. Mapping spaces. Segmentation. Dimensional reduction.

[Image: “the [2D] bowling ball on a bedsheet” analogy – a “down” gravity well, with hand holding tweezers placing placing a small particle on the grid.]

• Quanta Magazine > “A Century Later, New Math Smooths Out General Relativity” by Steve Nadis (November 30, 2023) – Mathematicians prove a theorem that illuminates the geometry of universes with tiny amounts of mass.

]]>… it was not until around 1980 that mathematicians proved, as part of a major theorem in

general relativity, thatan isolated physical system, or space, without any mass in it must be flat.This left unresolved the question of what a space looks like if it is almost a vacuum, having just a tiny amount of mass. Is it necessarily almost flat?

In a recent paper, Conghan Dong, a graduate student at Stony Brook University, and Antoine Song, an assistant professor at the

California Institute of Technology, proved thata sequence of curved spaces with smaller and smaller amounts of mass will eventually converge to a flat space with zero curvature.[Illustrating the approach to

denuded spacesvs. utter flatness] As a proxy for a space with small mass, he suggested, we might imagine a crumpled sheet of paper that, after being smoothed out again, still has sharp creases and folds. You could use a hole punch to remove the most prominent irregularities, leaving a slightly uneven piece of paper with some holes in it. As the size of those holes shrinks, so will the unevenness of the paper’s terrain. At the limit, you might say, the holes would shrink to zero, the mounds and ridges would disappear, and you’d be left with a uniformly smooth piece of paper — a genuine stand-in for flat space.

This recent Science Asylum video is an excellent overview of how the cosmic distance ladder evolved.

• YouTube > The Science Asylum > “We Can’t Measure* Distance In Outer Space!” (October 30, 2023)

]]>We can’t measure the distance to astronomical objects directly, so we have to be creative. That’s why we need the

cosmic distance ladder. It’s a serious of techniques we use tocalculate astronomical distances indirectly.Cold Open

Introduction

Radar Ranging

Inverse Square Law

StellarParallax

Standard Candles

CepheidVariable Stars

Type 1aSupernovas

CosmologicalRedshift

Summary

How many stars are there in the universe? How many black holes? Who cares? … what confidence is there in any estimate anyway?

Well, The Dark Energy Survey explores this matter.

• Big Think > “There are 40 quintillion black holes in our Universe” by Ethan Siegel (October 30, 2023) – LIGO and Virgo have detected scores of black holes, providing us with our first quasi-census.

By combining information about stars, black holes, and stellar and cosmic evolution all together, astronomers have the first robust estimate for black holes in the Universe: 40 quintillion. It’s more than almost anyone expected.

Key points

All told, astrophysicists conclude 40 quintillion (4 × 10^19) black holes exist within today’s Universe.

That equates to 1-2% of all stars eventually forming black holes: higher than all prior estimates.

If confirmed, this implies black holes comprise 0.04% of the

cosmic energy budget.

**References**

1. Black holes evidently abound in the center of our Milky Way according to this NPR article: “Center of the Milky Way Has Thousands of Black Holes, Study Shows” (April 4, 2018).

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