Tag: Cal’s Coffee

Screams And Thunders

On By rolcottIn Astronomy: Techniques, Physics: Waves, UncategorizedLeave a comment

Coffee time. I step into Cal’s shop and he’s all over me. ”Sy, have you heard about the the NASA sonification project?”

Susan puts down her mocha latte. “I didn’t like some of what they’ve released. Sounds too much like people screaming.”

Jeremy looks up from the textbook he’s reading. ”In space, no-one can hear you scream.”

Vinnie rumbles from his usual table by the door. “Any of these got anything to do with the Cosmic Hum?”

“They have nothing to do with each other, except they do. Spiral galaxies, too.”

“Huh?”
 ”Huh?”
  ”Huh?”
   ”Huh?”

“A mug of my usual, Cal, please, and a strawberry scone.”

“Sure, Sy, here ya go, but you can’t say something like that around here without you tellin’ us how come.”

“Does the name Bishop Berkeley ring a bell with anyone?”

Vinnie’s on it. ”That the ‘If a tree falls in the forest…‘ guy, right? Claimed there’s no sound unless somebody’s there to hear it?”

“And by extension, no sound outside human hearing range.”

“But bats and them use sound we can’t hear.”
 ”So do elephants and whales.”

“Well there you go. So are we agreed that he was wrong?”

“Not quite, Mr Moire. His definition of ‘sound‘ was different from one you’d like. He was a philosopher theorizing about perception, but you’re a physicist. You two don’t even define reality the same way.”

Vinnie’s rumble. ”Good shot, Jeremy. Sound is waves. Sy and me, we talked about them a lot. One molecule bangs into the next one and so on. The molecules don’t move forward, mostly, but the banging does. Sy showed me a video once. So yeah, people listening or not, that tree made a sound. There’s molecules up in space, so there’s sound up there, too, right, Sy?”

“Mmm, depends on where you are. And what sounds you’re equipped to listen for. The mechanism still works, things advancing a wave by bouncing off each other, but the wave’s length has to be longer than the average distance between the things.” <drawing Old Reliable, pulling up display> “Here’s that video Vinnie saw. I’ve marked two of the particles. You see them moving back and forth over about a wavelength. Suppose a much shorter wave comes along.”

“Umm… Each one would get a forward kick before they got back into position. They wouldn’t oscillate, they’d just keep moving in that direction. No sound wave, just a whoosh.”

“Right, Jeremy. Each out‑of‑sync interaction converts some of the wave’s oscillating energy into one‑way motion. The wave doesn’t get energy back. A dozen wavelengths along, no more wave. So the average distance between particles, we call it the mean free path, sets limits to the length and frequency of a viable wave. Our ears would say it filters out the treble.”

“Space ain’t quite empty so it still has a few atoms to bump together. What kinds of limits do we get out there?”

“Well, there’s degrees of empty. Interplanetary space has more atoms per cubic meter than interstellar which is more crowded than intergalactic. Nebulae and molecular clouds can be even less empty. Huge range, but in general we’re talking wavelengths longer than a million kilometers. Frequencies measured in months or years — low even for your voice, Vinnie.”

Jeremy gets a look on his face. ”One of my girlfriends is a soprano. We tested her in the audio lab and she could hit a note just under two kilohertz, that’s two thousand cycles per second. My top screech was below half that. I could scream in space, but I guess not low enough to be heard.”

“Yeah, keep that spacesuit helmet closed and be sure your radio intercom’s working.”

“Wait, what about screaming over the radio?”

“Radio operates with electromagnetic waves, not bumping atoms. Mean free path limits don’t apply. Radio’s frequency range is around a hundred megahertz, screeching’s no problem. Your broadcast equipment’s response range would set your limits.”

“Sy, those screamy sounds I objected to — you say they can’t have traveled across space as sound waves. Was that a radio transmission?”

“Maybe, Susan. From what I’ve read, we’ve picked up beaucoodles of radio sources, all different types and all over the sky. Each broadcasts a spectrum of different radio frequencies. Some of them are constant radiators, some vary at different rates. You may have heard a recording of a kilohertz variable source.”

<shudder> “All nasty treble, no bass or harmony.”

~~ Rich Olcott

  • Thanks to Alex, who raised several questions.

Shapes And Numbers

On By rolcottIn Mathematics: Spherical Harmonics, Physics: Quantum Mechanics, UncategorizedLeave a comment

I’m nursing my usual mug of eye‑opener in Cal’s Coffee Shop when astronomer Cathleen and chemist Susan chatter in and head for my table. Susan fires the first volley.

“Sy, those spherical harmonics you’ve posted don’t look anything like the atomic orbitals in my Chem text. Shouldn’t they?”
 ”How do you add and multiply shapes together?”
  ”What does the result even mean?”
   ”And what was that about solar seismology?”

The angular portion of the lowest‑energy spherical harmonics.
Adapted from work by Inigo.quilez, under CCA SA 3.0 license

“Whoa, have you guys taken interrogation lessons from Mr Feder? One at a time, please. Let’s start with the basics.” <sketching on a paper napkin> “For example, the J2 zonal harmonic depends only on the latitude, not on the longitude or the distance from the center, so whatever it does encircles the axis. Starting at the north pole and swinging down to the south pole, the blue line shows how J2 varies from 1.0 down to some negative decimal. At any latitude, whatever else is going on will be multiplied by the local value of J2.”

“The maximum is 1.0, huh? Something multiplied by a number less than 1 becomes even smaller. But what happens where J2 is zero? Or goes negative?”

“Wherever Jn‘s zero you’re multiplying by zero which makes that location a node. Furthermore, the zero extends along its latitude all around the sphere so the node’s a ring. J2‘s negative value range does just what you’d expect it to — multiply by the magnitude but flip the product’s sign. No real problem with that, but can you see the problem in drawing a polar graph of it?”

“Sure. The radius in a polar graph starts from zero at the center. A negative radius wouldn’t make sense mixed in with positives in the opposite direction.”

“Well it can, Cathleen, but you need to label it properly, make the negative region a different color or something. There are other ways to handle the problem. The most common is to square everything.” <another paper napkin> “That makes all the values positive.”

“But squaring a magnitude less than 1 makes it an even smaller multiplier.”

“That does distort the shapes a bit but it has absolutely no effect on where the nodes are. ’Nothin’ times nothin’ is nothin’,’ like the song says. Many of the Chem text orbital illustrations I’ve seen emphasize the peaks and nodes. That’s exactly what you’d get from a square‑everything approach. Makes sense in a quantum context, because the squared functions model electron charge distributions.”

“Thanks for the nod, Sy. We chemists care about charge peaks and nodes around atoms because they control molecular structures. Chemical bonds and reactions tend to localize near those places.”

“I aim for fairness, Susan. There is another way to handle a negative radius but it needs more context to look reasonable. Meanwhile, we’ve established that at any given latitude each Jn is just a number so let’s look at longitudes.” <a third paper napkin> “Here’s the first two sectorial harmonics plotted out in linear coordinates.”

“Looks familiar.”

“Mm‑hm. Similar principles, except that we’re looking at a full circle and the value at 360° must match the value at 0°. That’s why Cm always has an even node count — with an odd number you’d have -1 facing +1 and that’s not stable. In polar coordinates,” <the fourth paper napkin> “it’s like you’re looking down at the north pole. C0 says ‘no directional dependence,’ but C1 plays favorites. By the way, see how C1‘s negative radii in the 90°‑270° range flip direction to cover up the positives?”

“Ah, I see where you’re going, Sy. Each of these harmonics has a numeric value at each angle around the center. You’re going to tell us that we can multiply the shapes by multiplying their values point by point, one for each latitude for a J and each longitude for a C.”

“You’re way ahead of me as usual, Cathleen. You with us, Susan?”

“Oh, yes. In my head I multiplied your J2 by C0 and got a pz orbital.”

“I’m impressed.”
 ”Me, too.”

“Oh, I didn’t do it numerically. I just followed the nodes. J2 has two latitude nodes, C0 has no longitude nodes. There it is, easy‑peasy.”

~~ Rich Olcott

A Loose-end Lagniappe

On By rolcottIn Astronomy: Planetary Science, Mathematics: Spherical Harmonics, UncategorizedLeave a comment

<chirp, chirp> “Moire here.”

“We have some loose ends to tie up. Too early for pizza. Coffee at Cal’s?”

“Hello, ‘Walt‘. Fifteen minutes?”

“Confirmed.”

He’s at a back table, facing the door, of course. He points to the steaming mug and strawberry scone beside it on the table. I nod to acknowledge. ”So, Walt, what are these loose ends?”

“My people say that Juno‘s not on a 53‑day orbit any more. NASA’s jiggled it down to 33 days. What’s that do to the numbers you gave me?”

<sliding a folded paper scrap across the table> “I had a hunch you’d want more so I worked up estimates. Juno started with a 53‑day orbit but a Ganymede flyby dropped it to 43 days. A Europa flyby took Juno to a 38‑day orbit. Now it’s swerved by Io and we’re at 33 days. I threw in the 23‑day line for grins, no extra charge.”

“Half the orbit size but no significant change in the close‑in specs. That’s surprising.”

“Not really. It’s like a dog’s butt wagging its tail. At close approach, we call it perijove, Juno is only 76 500 kilometers out from Jupiter’s center. Its orbit thereabouts is pretty much nailed down by the big guy’s central field. But there’s no second attractor to constrain the orbit’s other extreme millions of kilometers out. Do an Oberth burn near perijove or arrange for a gravity tweak from a convenient moon, you get a big difference at the far end.”

“That wraps that.” <reaches for his cane, then settles back to do a Columbo> “Just one more thing, Moire. I came in with a question about the Sun’s effect on Juno. You took care of that pretty quick but spent a load of my time and consultancy budget on these spherical harmonics. How come?”

“As I recall, you and your people kept coming back for more detail. Also, the 225 000‑kilometer radius I got from R2‘s structure was essential in calculating these close‑in numbers. You’re getting your money’s worth. I’ll even throw in a lagniappe.”

“A free gift? I never trust them.”

“Such a mean world you live in, Walt.” <displaying an image on Old Reliable> “Here it is, take it or leave it.”

Top: F000 plus a time-varying contribution from F660
Bottom: C0 plus a time-varying contribution from C4

“What is it?”

“It’s a bridge between the physics of light and sound, and the physics of atoms and stars. When I say ‘coordinates,’ what words spring to your mind?”

“Traverse and elevation.”

“Interesting choice. Any other systems?”

“Mm, latitude, longitude and altitude. And x‑y‑z if you’re in a classroom.”

“Way beyond the classroom. You use spreadsheets, right?”

“Doesn’t everyone?”

“Rows‑columns‑sheets is x‑y‑z. On digital screens, pixels‑lines‑luminosity is x‑y‑z. Descarte’s rectilinear invention is so deeply embedded in our thinking we don’t even notice it. Perpendicular straight‑line coordinates fit things that are flat or nearly so, not so good for spheres and central‑force problems. Movement there is mostly about rotation, which is why your first two picks were angular instead of linear.”

“Okay, but our choice of coordinates is our choice. What have x‑y‑z or your Fnnm to do with natural things?”

“Overtones and resonance. Look at that black line in the movie. It could be a guitar string or a violin string, doesn’t matter. One end’s fixed to the instrument’s bridge, the other end’s under somebody’s finger. All other points on the string are free to move, subject to tension along the string. Then someone adds energy to the string by plucking or bowing it.”

“At one of those peaks or valleys, right?”

“Nope, anywhere, which goes to my point. The energy potentially could contort the string to any shape. Doesn’t happen. The only stable shapes are combinations of sine waves with an integer number of nodes, like C4‘s quartet. Adding even more energy gives you overtones, waves that add in‑between nodes to lower‑energy waves. C0‘s no‑nodes black line could run along x, y or z in any flat system.”

“So you’re going to tell me that your C‘s, J‘s and R‘s support wave structures for spheres.”

“Indeed. All four giant planets have stripes along their J arcs. Solar seismologists have uncovered C, R and maybe J wave structures inside the Sun.”

“Bye.”

“Don’t mention it.”

~ Rich Olcott

More Map Games

On By rolcottIn Chemistry, General: Fun Stuff, UncategorizedLeave a comment

Vinnie’s not in his usual afternoon spot at the table by the coffee shop door. Then I hear him. “Hey, Sy, over here.” He’s at the center table, surrounded by Cal’s usual clientele but they’re passing sheets of paper around. I worm my way through the crowd. ”What’s going on, Vinnie?”

“Me and Larry are both between piloting assignments so we spent the weekend playing with that map software he bought. He’s figured out how to link it with online databases so we can map just about anything all different ways. Hey, you’re into history, right?”

“Some, yes.”

“This one’s about how far countries go back. I kinda thought countries have always just been there, but no. We found a list of when each country got to have their own government independent of somebody else in charge, so we made this map with the oldest countries the darkest. Look how pale most of the world is. Look at us — the USA is the tenth oldest country. I couldn’t believe it.”

“Ah, I know Denmark started with the Vikings soon after the Roman Empire collapsed. Hungary’s history as a kingdom started about the same time. Then there’s a handful of old states defended by mountains — yup, I see Nepal and Switzerland. Andorra, Liechtenstein and San Marino are in the same category, but they’re too small for this map to show them.”

“You missed the Netherlands from 1579 when they broke free from Spain. No mountains. Larry graphed the numbers down in the corner.”

“Mm-hm. I see two waves. The USA and France started the first one in the late 1700s. That took in most of the New World by the mid‑1800s. Then two World Wars and ‘Katie, bar the door!‘ I hadn’t realized how abruptly de‑colonization took place. Wow. All of Africa and most of southeast Asia became free‑standing countries in just half a century. What’s with Russia — missing data?”

“Gotcha, Sy. That was 1991, when the USSR broke up. Bang! Twenty new countries, all near the top of the scale.” <shuffling papers> “Here’s another one you’ll like. Larry has this theory that countries with lots of neighbors get militarized ’cause they’ve always got a war going on somewhere but if you don’t share borders with hardly anyone, no problem. He did up this map to check his theory. See Canada’s light blue ’cause it’s got only us, we’re dark blue ’cause we got Canada and Mexico. Dark green countries got four and so on. Whaddaya see here?”

“Uh-oh.”

“Yeah. Top of the list, 14 each, are Russia and China who are not best buddies with hardly anybody. Brazil’s got 10, but rainforest is probably as good as mountains.”

“Good point.”

“Excuse me, guys, but I’ve got personal counter‑example experience.”

“Hi, Susan. What’s that?”

“I grew up in Korea, right? Only 2 neighbors, China and Japan, but we’ve got a tough history because each of them just used us as a bridge to get to the other one. Tell Larry it makes a difference who you share a border with.”

“I’ll pass the word. Wait a minute…” <more paper shuffling> “Here’s one we did just for you, Ms Chemist.”

“Weird. How do you even read this?”

“We ran into a problem with the standard maps when we colored each country according to how many chemical elements were discovered there. Most of the action mushed into western Europe’s small area when we showed the other countries. Larry tried a bunch of different projections. This one’s like a fish‑eye lens looking down near the North Pole. See, Russia’s spread around the center but Europe’s bigger?”

“Ah, once I know what to look for it snaps in.”

“I cropped it down to the oval ’cause all the blue sea didn’t fit on the page.”

“Understandable. Lesseee… The UK’s on top mostly because of Wollaston’s geochemistry, Humphry Davy’s work on electropositive metals, and Ramsay isolating the inert gases. The USA owes its second‑place status to Seaborg’s isotope factory at UCal Berkeley. One step down, Germany, France and Sweden ran a discovery horse‑race during the 1800s. Russia came on strong with radioactives but that was late in the game.”

“Wait, Susan. How’d the purples get into this? No big labs there.”

“Except for nihonium, it’s mostly right‑place‑right‑time luck. India gets credit because a French astronomer observing an eclipse from there spotted a helium line in the solar spectrum. Later, an Italian recorded the line on Earth and a Scot isolated the gas.”

~~ Rich Olcott

Screaming Out Of Space

On By rolcottIn Astronomy: Planetary Science, Mathematics: Spherical Harmonics, UncategorizedLeave a comment

Cal (formerly known as Al) comes over to our table in his coffee shop. “Lessee if I got this right. Cathleen is smug twice. First time because the new results from Juno‘s data say her hunch is right that Jupiter’s atmosphere moves like cylinders inside each other. Nearly cylinders, anyhow. Second smug because Sy used the Juno data to draw a math picture he says shows the Great Red Spot but I’m lookin’ at it and I don’t see how your wiggle‑waggles show a Spot. That’s a weird map, so why’re you smug about it, Cathleen?”

“The map’s weird because it’s abstract and way different from the maps you’re used to. It’s also weird because of how the data was collected. Sy, you tell him about the arcs.”

“Okay. Umm… Cal, the maps you’re familiar with are two‑dimensional. City maps show you north‑south and east‑west, that’s one dimension for each direction pair. Maps for bigger‑scale territories use latitude for north‑south and longitude for east‑west but the principle’s the same. The Kaspi group’s calculations from Juno‘s orbit data give us a recipe for only a one‑dimensional map. They show how Jupiter’s gravity varies by latitude, nothing about longitude. We could plot that as a rectangle, latitude along the x‑axis, relative strength along the y‑axis. I thought I’d learn more by wrapping the x‑axis around the planet so we could look for correlations with Jupiter’s geography. I found something and that’s why Cathleen’s smug. Me, too.”

“Why latitude but nothing about longitude?”

“Because of the way Juno‘s orbit works. The spacecraft’s not hovering over the planet or even circling it like the ISS circles Earth. NASA wanted to minimize Juno‘s exposure to Jupiter’s intense magnetic and radiation fields. The craft spends most of its 53‑day orbit at extreme distance, up to millions of kilometers out. When it approaches, it screams in at about 41 kilometers per second, that’s 91 700 mph, on a mostly north‑to‑south vector so it sees all latitudes from a few thousand kilometers above the cloud‑tops. Close approach lasts only about three hours, for the whole planet, and then the thing is on its way out again. During that three hours, the planet rotates about 120° underneath Juno so we don’t have a straight vertical N‑S pass down the planet’s face. Gathering useful longitude data’s going to take a lot more orbits.”

“So you’re sayin’ Juno felt gravity glitches at all different angles going pole to pole, but only some of the angles going round and round.”

“Exactly.”

“So now explain the wiggle‑waggles.”

“They represent parts‑per‑million variations in the field pulling Juno towards Jupiter at each latitude. Where the craft is over a more massive region it’s pulled a bit inwards and Sy’s map shows that as a green bump. Over a lighter region Juno‘s free to move outward a little and the map shows a pink dip. Kaspi and company interpret the heaviness just north of the equator to be a dense inward flow of gas all around the planet. Maybe it is. Sy and I think the pink droplet south of the equator could reflect the Great Red Spot lowering the average mass at its latitude. Maybe it is. As always, we need more data, okay? Now I’ve got questions for you, Sy.”

“Shoot.”

“You built your map by multiplying each Jn‑shape by its Kaspi gravitational intensity then adding the multiplied shapes together. But you only used Jn‑shapes with integer names. Is there a J½?”

“Some mathematicians play with fractional J‑thingies but I’ve not followed that topic.”

“Understandable. Next question — the J‘s look so much like sine waves. Why not just use sine‑shapes?”

“I used Jn‑shapes because that’s how Kaspi’s group stated their results. They had no choice in the matter. Jn‑shapes naturally appear in spherical system math. The nice thing about Jn‑shapes is that n provides a sort of wavelength scale. For instance, J35 divides Jupiter’s pole‑to‑pole arc into 36 segments each as wide as Earth’s diameter. Here’s a plot of intensity against n.”

Adapted from Kaspi, Figure 2a

“Left to right, red light to blue.”

“Exactly.”

~ Rich Olcott

Zoning Out over Jupiter

On By rolcottIn Astronomy: Planetary Science, Mathematics: Spherical Harmonics, Physics: Waves, UncategorizedLeave a comment

I’m nursing my usual mug of eye‑opener in Cal’s Coffee Shop when astronomer Cathleen and chemist Susan chatter in. “Morning, ladies. Cathleen, prepare to be even more smug.”

“Ooo, what should I be smug about?”

“Your Jupiter suggestion. Grab some coffee and a couple of chairs.” <screen‑tapping on Old Reliable> “Ready? First step — purple and violet. You’ll never see violet or purple light coming from a standard video screen.”

“He’s going spectrum‑y on us, right, Cathleen?”

“More like anti‑spectrum‑y, Susan. Purple light doesn’t exist in the spectrum. We only perceive that color when we see red mixed with blue like that second band on Sy’s display. Violet light is a thing in nature, we can see it in flowers and dyes and rainbows beyond blue. Standard screens can’t show violet because their LEDs just emit red, blue and green wavelengths. Old Reliable uses mixtures of those three to fake all its colors. Where are you going with this, Sy?””

“Deeper into Physics. Cast your eyes upon the squiggles to the right. The one in the middle represents the lightwave coming from purple‑in‑the‑middle. The waveform’s jaggedy, but if you compare peaks and troughs you can see its shape is the sum of the red and blue shapes. I scaled the graphs up from 700 nanometers for red and 450 for blue.”

“Straightforward spectroscopy, Sy, Fourier analysis of a complicated linear waveform. Some astronomers make their living using that principle. So do audio engineers and lots of other people.”

“Patience, Cathleen, I’m going beyond linear. Fourier’s work applies to variation along a line. Legendre and Poisson extended the analysis to—”

“Aah, spherical harmonics! I remember them from Physical Chemistry class. They’re what gives shapes to atoms. They’ve got electron shells arranged around the nucleus. Electron charge stays as close to the nucleus as quantum will let it. Atoms absorb light energy by moving charge away from there. If the atom’s in a magnetic field or near other atoms that gives it a z-axis direction then the shells split into wavey lumps going to the poles and different directions and that’s your p-, d– and f-orbitals. Bigger shells have more room and they make weird forms but only the transition metals care about that.”

The angular portion of the lowest-energy spherical harmonics
Credit: Inigo.quilez, under CCA SA 3.0 license
Adapted from Wieczorek and Meschede under CC BY-NC-ND 4.0

“Considering you left out all the math, Susan, that’s a reasonable summary. I prefer to think of spherical harmonics as combinations of wave shapes at right angles. Imagine a spherical blob of water floating in space. If you tap it on top, waves ripple down to the bottom and back up again and maybe back down again. Those are zonal waves. A zonal harmonic averages over all E‑W longitudes at each N‑S latitude. Or you could stroke the blob on the side and set up a sectorial wave pattern that averages latitudes.”

“How about center‑out radial waves?”

“Susan’s shells do that job. My point was going to be that what sine waves do for characterizing linear things like sound and light, spherical harmonics do for central‑force systems. We describe charge in atoms, yes, but also sound coming from an explosion, heat circulating in a star, gravity shaping a planet. Specifically, Jupiter. Kaspi’s paper you gave me, Cathleen, I read it all the way to the Results table at the tail end. That was the rabbit‑hole.”

“Oh? What’s in the table?”

“Jupiter’s zonal harmonics — J‑names in the first column, J‑intensities in the second. Jn‘s shape resembles a sine wave and has n zeroes. Jupiter’s never‑zero central field is J0. Jn increases or decreases J0‘s strength wherever it’s non‑zero. For Jupiter that’s mostly by parts per million. What’s cool is the pattern you see when you total the dominating Jeven contributions.”

Data from Kaspi, et al.

Cathleen’s squinting in thought. “Hmm… green zone A would be excess gravity from Jupiter’s equatorial bulge. B‘s excess is right where Kaspi proposed the heavy downflow. Ah‑HAH! C‘s pink deficit zone’s right on top of the Great Red Spot’s buoyant updraft. Perfect! Okay, I’m smug.”

~ Rich Olcott

Revising The Model

On By rolcottIn Astronomy: Planetary Science, Uncategorized4 Comments

Cathleen’s perched at a table in Cal’s Coffee Shop, sipping a latte and looking smug. “Hi, Sy.”

“Hi, yourself. Did somebody you don’t like get a well‑deserved comeuppance?”

“Nothing that juicy. Just an old hunch that’s gotten some strong new supporting evidence. I love it when that happens.”

“So what’s the hunch and what’s the evidence?”

“You’ve already heard the hunch.” <dialing up an image on her phone> “Remember this sketch?”

“Hmmm, yeah, you and Vinnie were debating Jupiter’s atmosphere. Its massive airflows could self‑organize as an oniony nest of concentric spherical shells, or maybe concentric cylinders like that picture on your phone. Later on Vinnie thought up a more dynamic option — cylindrical shells encasing sets of smaller tornados like roller bearings. You shot that one down, right?”

“Mostly. I did admit something like that might work at the poles. Anyway, I’ve liked the concentric cylinders model for quite a while. This paper I just read says I’m almost but not quite right. Kaspi and company’s data says the cylinders are cone sections, not cylinders, and they’re not north‑south symmetrical.” <dialing up another image> “It’s like this except I’ve exaggerated the angles.”

“Doesn’t look all that different to me. Congratulations on the near‑win. What’s the new model based on? Did Juno drop another probe into the atmosphere?”

“Nope. Remote sensing, down as far as 3000 kilometers.”

“I thought Jupiter’s cloud decks blocked infrared.”

“Another nope. Not infrared sensing, gravity.”

“Didn’t know Juno carried a gravimeter.”

“It doesn’t, that’d be way too heavy and complex. Juno itself was the remote sensor. Whenever NASA’s Deep Space Network captured a data transmission from Juno, they also recorded the incoming radio signal’s precise frequency. Juno‘s sending frequency is a known quantity. Red‑shifts and blue‑shifts as received told us Juno‘s then‑current velocity relative to Earth. The shifts are in the parts‑per‑million range, tiny, but each speed‑up or slow‑down carries information about Jupiter’s gravitational field at that point in Juno‘s orbit. Given velocity data for enough points along enough orbits, you can build a gravity atlas. This paper reports what the researchers got from orbits 1 through 37.”

“Cute idea. They’ve built the atlas, I suppose, but what can gravity say about your wind cylinders?”

“Winds in Jupiter’s atmosphere are driven by heat rising from the core. Put a balloon 3000 kilometers down. Heated air inside the balloon expands. That has two effects. One, the balloon is less dense than its surroundings so it rises. Two, the work of expanding against outside pressure drains thermal energy and cools the balloon’s air molecules. The process continues until the balloon gets up to where its temperature and pressure match what’s outside, right?”

“Which is probably going to be well above 3000 kilometers. Hmm… if you’ve got lots of balloons doing that, as they fly upward they leave a vacuum sort of. Excess balloons up top will be pulled downward to fill the void.”

“Now organize all those balloons in a couple of columns, one going up and one down. Will they have equal mass?”

“Interesting. No, they won’t. The rising column rises because it’s less dense than its surroundings and the falling column falls because it’s more dense. More mass per unit volume in the falling column so that’s heavier.”

“Eighteenth Century Physics. Planetary rotation forces columns of each kind to merge into a nest of separate cones. Rising‑column warm cones support Jupiter’s white ammonia‑ice zones. Falling‑column cool cones disclose red‑brown belts. The gravity field is stronger above the dense falling regions, weaker over the light rising ones. Juno responded to gravity’s wobbles; the researchers built their models to fit Juno‘s wobbles. The best models aren’t quite concentric cylinders, because the cones tilt poleward. This graphic tells the story. The rectangle shows a 3000‑kilometer vertical section. The between-shell boundaries are effective — the paper specifically says that mass transport inward from the outermost shell is insignificant.”

Adapted from NASA/JPL-Caltech/SSI/SWRI/MSSS/ASI/ INAF/JIRAM/Björn Jónsson
CC BY 3.0

“You said the data’s asymmetric?”

“Yep. The strongest part of the gravitational signal came from flow angling down and equator‑ward, 21°N to 13°N.”

“Why’s that?”

“Maybe the Great Red Spot down south drives everything northward. We don’t know.”

~ Rich Olcott

The Name’s Not The Same

On By rolcottIn General: Fun Stuff, UncategorizedLeave a comment

The regular Thursday night meeting of the Acme Pizza and Science Society around the big circular table at Pizza Eddie’s. Al comes in, hair afire and ready to bite the heads off tenpenny nails. “This is the last straw!” <flings down yet another astronomy magazine>. “Look at this!”

I pick up the issue. “Looks like the lead article’s about the Psyche mission to the Psyche asteroid. You got a problem with that?”

“Nah, that’s just fine, exciting even. Look at the address label.”

“Ah, I see your objection. Instead of your first name it says ‘A. I.’ like those are your initials. Are they?”

“No. Never had a middle initial until the Navy gave me ‘N‘ for ‘No middle initial‘ and I dropped that soon as I got out.”

“So where’d they get the ‘I’?”

“That’s what chafes my cheeks, Vinnie, people messing with my name. All this stuff going on these days about Artificial Intelligence which everybody calls ‘AI’ which looks too flippin’ much like Al. People have been ribbing me about it since ChatGPT hit the street. They come in here asking me for virtual coffee or wanting to know about my ALgorithms. One guy claimed I parked a driverless coffee machine back of the kitchen. But it’s not just jokes. I get calls asking for programming help with languages I never heard of. My checks have my name as Al but the bank lady gives me grief because I don’t sign them with A. I.”

“You’ve got a good point there. When someone chooses a name, that name’s important to them. I know whole families where everyone has a ‘go‑by‘ name. First class I ever taught, I opened by calling the role so I could tie names to faces. I started out calling out first names but quickly learned that most of the men and half the women went by middle names — this was in the South where that’s common but still. Anyway, I called first and middle names until I got to this one kid. He’d gone through three years of college going by ‘C-M’ until I blew his cover by asking which student was named Clyde and it was him. I don’t think he ever forgave me.”

“I know the feeling, Cathleen. None of the teachers could handle my full name. This magazine’s stupid spell‑checker musta corrected me wrong. I want a new name that doesn’t get messed up.”

“Al’s not your full name?”

“No, it’s Aloysius which I don’t like. No-one can spell it, or say it right if they see it written out. I got named after my Mom’s favorite uncle before I could vote against it. I’ve been going by Al ever since I knew better.”

“We need to figure you a new name that looks different but sounds almost the same so you’ll recognize it when we holler at you, right?”

“That’s about it, Vinnie. Whaddaya got?”

“A negative to begin with. We can rule out Hal, the killer computer in the 2001 movie. Don’t want to see our physicist here walk up for a strawberry scone and get ‘I’m afraid I can’t do that, Sy.’ Haw!”

“How about Sal?”

Eddie waves it away. “My Uncle Salvatore’s already got that. One’s enough.”

I read off Old Reliable’s screen. “Baal was a god worshipped by some of the Old Testament enemy tribes, eventually turned into Beelzebub. That won’t do. And ‘mal‘ means ‘bad‘ in Spanish.”

Resident chemist Susan giggles. “I don’t suppose you’d be happy if I greeted you with a cheery, ‘Hey, Gal‘. Oh, wait, I’ve got a Chemistry thing for us. ‘Cal‘ is the standard abbreviation for ‘calorie,’ one of the old‑time measures of heat energy before everybody settled on the joule. What do you think of ‘Cal‘? Hot and cool and rugged enough for you?”

“Hmm… I like it. ‘Cal’s Coffee‘ even has that market‑winner k’‑kuh sound like Krispy Kreme and Captain Crunch and Crispy Critters. It’s official — from now on, Cal is my official go‑by name. Thanks, Susan.”

She grins. “First time I’ve named an adult. Hi, Cal.”
 ”Hi, Cal.”
  ”Hi, Cal.”
   ”Hi, Cal. Now about that magazine article…”

Adapted from a photo by Edward Eyer

~~ Rich Olcott

Three Feet High And Rising

On By rolcottIn Astronomy: Planetary Science, General: Serious Stuff, Uncategorized1 Comment

“Bless you, Al, for your air conditioning and your iced coffee.”

“Hiya, Susan. Yeah, you guys do look a little warm. What’ll you have, Sy and Mr Feder?”

“Just my usual mug of mud, Al, and a strawberry scone. Put Susan’s and my orders on Mr Feder’s tab, he’s been asking us questions.”

“Oh? Well, I suppose, but in that case I get another question. Cold brew for me, Al, with ice and put a shot of vanilla in there.”

“So what’s your question?”

“Is sea level rising or not? I got this cousin he keeps sending me proofs it ain’t but I’m reading how NYC’s talking big bucks to build sea walls around Manhattan and everything. Sounds like a big boondoggle.” <pulling a crumpled piece of paper from his pocket and smoothing it out a little> “Here’s something he’s sent me a couple times.”

“That’s bogus, Mr Feder. They don’t tell us moon phase or time of day for either photo. We can’t evaluate the claim without that information. The 28‑day lunar tidal cycle and the 24‑hour solar cycle can reinforce or cancel each other. Either picture could be a spring tide or a neap tide or anything in‑between. That’s a difference of two meters or more.”

“Sy. the meme’s own pictures belie its claim. Look close at the base of the tower. The water in the new picture covers that sloping part of the base that was completely above the surface in the old photo. A zero centimeter rise, my left foot.”

“Good point, Susan. Mind if I join the conversation from a geologist’s perspective? And yes, we have lots of independent data sources that show sea levels are rising in general.”

“Dive right in, Kareem, but I thought you were an old‑rocks guy.”

“I am, but I study old rocks to learn about the rise and fall of land masses. Sea level variation is an important part of that story. It’s way more complicated than what that photo pretends to deny.”

“Okay, I get that tides go up and down so you average ’em out over a day, right? What’s so hard?”

“Your average will be invalid two weeks later, Mr Feder, like Sy said. To suppress the the Sun’s and Moon’s cyclic variations you’d have to take data for a full year, at least, although a decade would be better.”

“I thought they went like clockwork.”

“They do, mostly, but the Earth doesn’t. There’s several kinds of wobbles, a few of which may recently have changed because Eurasia weighs less.”

“Huh?”
 ”Huh?”
  ”Huh?”

“Mm-hm, its continental interior is drying out, water fleeing the soil and going everywhere else. That’s 10% of the planet’s surface area, all in the Northern hemisphere. Redistributing so much water to the Southern hemisphere’s oceans changes the balance. The world will spin different. Besides, the sea’s not all that level.”

“Sea level’s not level?”

“Nope. Surely you’ve sloshed water in a sink or bathtub. The sea sloshes, too, counterclockwise. Galileo thought sloshing completely accounted for tides, but that was before Newton showed that the Moon’s gravity drives them. NASA used satellite data to build a fascinating video of sea height all over the world. The sea on one side of New Zealand is always about 2 meters higher than on the opposite side but the peak tide rotates. Then there’s storm surges, tsunamis, seiche resonances from coastal and seafloor terrain, gravitational irregularities, lots of local effects.”

Adapted from a video by NASA’s Scientific Visualization Studio

Susan, a chemist trained to consider conservation of mass, perks up. “Wait. Greenland and Antarctica are both melting, too. That water plus Eurasia’s has to raise sea level.”

“Not so much. Yes, the melting frees up water mass that had been locked up as land-bound ice. But on the other hand, it also counteracts sea rise’s major driver.”

“Which is?”

“Expansion of hot water. I did a quick calculation. The Mediterranean Sea averages 1500 meters deep and about 15°C in the wintertime. Suppose it all warms up to 35°C. Its sea level would rise by about 3.3 meters, that’s 10 feet! Unfortunately, not much of Greenland’s chilly outflow will get past the Straits of Gibraltar.”

~~ Rich Olcott

Not Silly-Season Stuff, Maybe

On By rolcottIn Chemistry, Physics: Electromagnetism, UncategorizedLeave a comment

“Keep up the pace, Mr Feder, air conditioning is just up ahead.”

“Gotta stop to breathe, Moire, but I got just one more question.”

“A brief pause, then. What’s your question?”

“What’s all this about LK99 being a superconductor? Except it ain’t? Except maybe it is? What is LK99, anyway, and how do superconductors work? <puffing>”

“So many question marks for just one question. Are you done?”

“And why do news editors care?”

“There’s lots of ways we’d put superconductivity to work if it didn’t need liquid‑helium temperatures. Efficient electric power transmission, portable MRI machines, maglev trains, all kinds of advances, maybe even Star Trek tricorders.”

“Okay, I get how zero‑resistance superconductive wires would be great for power transmission, but how do all those other things have anything to do with it?”

“They depend on superconductivity’s conjoined twin, diamagnetism.”

“Dia—?”

“Means ‘against.’ It’s sort of an application of Newton’s Third Law.”

“That’s the one says, ‘If you push on the Universe it pushes back,’ right?”

“Very good, Mr Feder. In electromagnetism that’s called Lenz’ Law. Suppose you bring a magnet towards some active conductor, say a moving sheet of copper. Or maybe it’s already carrying an electric current. Either way, the magnet’s field makes charge carriers in the sheet move perpendicular to the field and to the prevailing motion. That’s an eddy current.”

“How come?”

“Because quantum and I’m not about to get into that in this heat. Emil Lenz didn’t propose a mechanism when he discovered his Law in 1834 but it works. What’s interesting is what happens next. The eddy current generates its own magnetic field that opposes your magnet’s field. There’s your push‑back and it’s called diamagnetism.”

“I see where you’re going, Moire. With a superconductor there’s zero resistance and those eddy currents get big, right?”

“In theory they could be infinite. In practice they’re exactly strong enough to cancel out any external magnetic field, up to a limit that depends on the material. A maglev train’s superconducting pads would float above its superconducting track until someone loads it too heavily.”

“What about portable MRI you said? It’s not like someone’s gonna stand on one.”

“A portable MRI would require a really strong magnet that doesn’t need plugging in. Take that superconducting sheet and bend it into a doughnut. Run your magnet through the hole a few times to start a current. That current will run forever and so will the magnetic field it generates, no additional power required. You can make the field as strong as you like, again within a limit that depends on the material.”

“Speaking of materials, what’s the limit for that LK99 stuff?”

“Ah, just in time! Ahoy, Susan! Out for a walk yourself, I see. We’re on our way to Al’s for coffee and air conditioning. Mr Feder’s got a question that’s more up your Chemistry alley than my Physics.”

“LK99, right? It’s so newsy.”

“Yeah. What is it? Does it superconduct or not?”

“Those answers have been changing by the week. Chemically, it’s basically lead phosphate but with copper ions replacing some of the lead ions.”

“They can do that?”

“Oh yes, but not as neatly as we’d like. Structurally, LK99’s an oxide framework in the apatite class — a lattice of oxygens with phosphorus ions sitting in most of the holes in the lattice, lead ions in some of the others. Natural apatite minerals also have a sprinkling of hydroxides, fluorides or chlorides, but the reported synthesis doesn’t include a source for any of those.”

“Synthesis — so the stuff is hand‑made?”

“Mm‑hm, from a series of sold‑state reactions. Those can be tricky — you grind each of your reactants to a fine powder, mix the powders, seal them in a tube and bake at high temperature for hours. The heat scrambles the lattices. The atoms can settle wherever they want, mostly. I think that’s part of the problem.”

“Like maybe they don’t?”

“Maybe. There are uncontrollable variables — grinding precision, grain size distribution, mixing details, reaction tube material, undetected but critical impurities — so many. That’s probably why other labs haven’t been able to duplicate the results. Superconductivity might be so structure‑sensitive that you have to prepare your sample j‑u‑s‑t right.”

~~ Rich Olcott