Tag: Cal’s Coffee

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

LIGO And NANOGrav

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

Afternoon coffee time, but Al’s place is a little noisier than usual. “Hey, Sy, come here and settle this.”

“Settle what, Al? Hi, Vinnie.”

<waves magazine> “This NANOGrav thing, they claim it’s a brand‑new kind of gravity wave. What’s that about?”

“Does it really say, ‘gravity wave‘? Let me see that. … <sigh> Press release journalism at its finest. ‘Gravity waves’ and ‘gravitational waves’ are two entirely different things.”

“I kinda remember you wrote about that, but it was so long ago I forget how they’re different.”

“Gravity waves happen in a fluid, like air or the ocean. Some disturbance, like a heat spike or an underwater landslide, pushes part of the fluid upward relative to a center of gravity. Gravity acts to pull that part down again but in the meantime the fluid’s own internal forces spread the initial up‑shift outwards. Adjacent fluid segments pull each other up and down and that’s a gravity wave. The whole process keeps going until friction dissipates the energy.”

“Gravitational waves don’t do that?”

“No, because gravitational waves temporarily modify the shape of space itself. The center doesn’t go up and down, it…” <showing a file on Old Reliable> “Here, see for yourself what happens. It’s called quadrupolar distortion. Mind you, the effects are tiny percentagewise which is why the LIGO apparatus had to be built kilometer‑scale in order to measure sub‑femtometer variations. The LIGO engineers took serious precautions to prevent gravity waves from masquerading as gravitational waves.”

“Alright, so now we’ve almost got used to LIGO machines catching these waves from colliding black holes and such. How are NANOGrav waves different?”

“Is infrared light different from visible light?”

“The Hubble sees visible but the Webb sees infrared.”

“Figures you’d have that cold, Al. What I think Sy’s getting at is they’re both electromagnetic even though we only see one of them. You’re gonna say the same for these new gravitational waves, right, Sy?”

“Got it in one, Vinnie. There’s only one electromagnetic field in the Universe but lots of waves running through it. Visible light is about moving charge between energy levels in atoms or molecules which is how the visual proteins in our eyes pick it up. Infrared can’t excite electrons. It can only waggle molecule parts which is why we feel it as heat. Same way, there’s only one gravitational field but lots of waves running through it. The LIGO devices are tuned to pick up drastic changes like the <ahem> massive energy release from a black hole collision.”

“You said ‘tuned‘. Gravitational waves got frequencies?”

“Sure. And just like light, high frequencies reflect high‑energy processes. LIGO detects waves in the kilohertz range, thousands of peaks per second. NANOGrav’s detection range is sub‑nanohertz, where one cycle can take years to complete. Amazingly low energy.”

“How can they detect anything that slow?”

“With really good clocks and a great deal of patience. The new reports are based on fifteen years of data, half a billion seconds counted out in nanoseconds.”

“Hey, wait a minute. LIGO’s only half‑a‑dozen years old. Where’d they get the extra data from, the future?”

“Of course not. Do you remember us working out how LIGO works? The center sends out a laser pulse along two perpendicular arms, then compares the two travel times when the pulse is reflected back. Light’s distance‑per‑time is constant, right? When a passing gravitational wave squeezes space along one arm, the pulse in that arm completes its round trip faster. The two times don’t match any more and everyone gets excited.”

“Sounds familiar.”

“Good. NANOGrav also uses a timing‑based strategy, but it depends on pulsars instead of lasers. Before you ask, a pulsar is a rotating neutron star that blasts a beam of electromagnetic radiation. What makes it a pulsar is that the beam points away from the rotation axis. We only catch a pulse when the beam points straight at us like a lighthouse or airport beacon. Radio and X‑ray observatories have been watching these beasts for half a century but it’s only in the past 15 years that our clocks have gotten good enough to register timing hiccups when a gravitational wave passes between us and a pulsar.”

~ Rich Olcott

Reflection, Rotation And Spacetime

On By rolcottIn Cosmology, Mathematics, Physics: Einstein, UncategorizedLeave a comment

“Afternoon, Al.”

“Hiya, Sy. Hey, which of these two scones d’ya like better?”

“”Mm … this oniony one, sorta. The other is too vegetable for me ‑ grass, I think, and maybe asparagus? What’s going on?”

“Experimenting, Sy, experimenting. I’m going for ‘Taste of Spring.’ The first one was spring onion, the second was fiddlehead ferns. I picked ’em myself.”

“Very seasonal, but I’m afraid neither goes well with coffee. I’ll take a caramel scone, please, plus a mug of my usual mud.”

“Aw, Sy, caramel’s a winter flavor. Here you go. Say, while you’re here, maybe you could clear up something for me?”

“I can try. What’s the something?”

“After your multiverse series I got out my astronomy magazines to read up on the Big Bang. Several of the articles said that we’ve gone through several … um, I think they said ‘epochs‘ … separated by episodes of symmetry breaking. What’s that all about?”

“It’s about a central notion in modern Physics. Name me some kinds of symmetry.”

“Mmm, there’s left‑right, of course, and the turning kind like a snowflake has. Come to think — I like listening to Bach and Vivaldi when I’m planet‑watching. I don’t know why but their stuff reminds me of geometry and feels like symmetry.”

“Would it help to know that the word comes from the Greek for ‘same measure‘? Symmetry is about transformations, like your mirror and rotation operations, that affect a system but don’t significantly change to its measurable properties. Rotate that snowflake 60° and it looks exactly the same. Both the geometric symmetries you named are two‑dimensional but the principle applies all over the place. Bach and the whole Baroque era were just saturated with symmetry. His music was so regular it even looked good on the page. Even buildings and artworks back then were planned to look balanced, as much mass and structure on the left as on the right.”

“I don’t read music, just listen to it. Why does Bach sound symmetric?”

“There’s another kind of symmetry, called a ‘translation‘ don’t ask why, where the transformation moves something along a line within some larger structure. That paper napkin dispenser, for instance. It’s got a stack of napkins that all look alike. I pull one off, napkins move up one unit but the stack doesn’t look any different.”

“Except I gotta refill it when it runs low, but I get your drift. You’re saying Bach takes a phrase and repeats it over and over and that sounds like translational symmetry along the music’s timeline.”

“Yup, maybe up or down a few tones, maybe a different register or instrument. The repeats are the thing. Play his Third Brandenberg Concerto next time you’re at your telescope, you’ll see what I mean.”

“Symmetry’s not just math then.”

“Like I said, it’s everywhere. You’ve seen diagrams of DNA’s spiral staircase. It combines translation with rotation symmetry, does about 10 translation steps per turn, over and over. The Universe has a symmetry you don’t see at all. No‑one did until Lorentz and Poincaré revised Heaviside’s version of Maxwell’s electromagnetism equations for Minkowski space. Einstein, Hilbert and Grossman used that work to give us and the Universe a new symmetry.”

“Einstein didn’t do the math?”

“The crew I just named were world‑class in math, he wasn’t. Einstein’s strengths were his physical intuition and his ability to pick problems his math buddies would find interesting. Look, Newton’s Universe depends on absolute space and time. The distance between two objects at a given time is always the same, no matter who’s measuring it or how fast anyone is moving. All observers measure the same duration between two incidents regardless. Follow me?”

“Makes sense. That’s how things work hereabouts, anyway.”

“That’s how they work everywhere until you get to high speeds or high gravity. Lorentz proved that the distances and durations you measure depend on your velocity relative to what you’re measuring. Extreme cases lead to inconsistent numbers. Newton’s absolute space and time are pliable. To Einstein such instability was an abomination. Physics needs a firm foundation, a symmetry between all observers to support consistent measurements throughout the Universe. Einstein’s Relativity Theory rescued Physics with symmetrical mathematical transformations that enforce consistency.”

~~ Rich Olcott

Metrological Extremes

On By rolcottIn Uncategorized1 Comment

Al’s coffee shop smells festive. “Hiya, Sy. Can I interest you in a peppermint latte this morning?”

Adapted from a YouTube video contributed by NPL(UK)

“You know me better than that, Al. My usual black mud, please. Hmm… What flavor’s hiding under the chocolate frosting on the scone rack?”

“Strawberry.”

“In that case I’ll take two. Your latest artwork behind the cash register is more a scroll than a poster.”

“You noticed. Yeah, it’s very cool but I don’t understand a couple things.”

“Oh? Like what?”

“Like what’s NPL, for starters, but mostly what the poster’s even about. I get that it’s science-y and my Physics and Astronomy customers chuckle at it, but…”

“Well, for starters, NPL is the United Kingdom’s National Physical Laboratory. In USA terms they’re a little bit like a mixture of NIST and what used to be Bell Labs with a side order of DARPA. They were early supporters of high‑precision instrumentation, computer and network tech, lots of cutting‑edge stuff until they were privatized and the company that mostly bought them lost a whole lot of money. Now they’re back to a government plus academy structure but they’re still a going concern, one of the major drivers behind the SI conventions.”

“You wrote about that a while ago, din’tcha?”

“Did a whole series that started with revising the official mass standard and wound up at the full set of Système International basic and derived units. Pretty boring until you realize that precise measurement has been crucial to practically all manufacturing since the introduction of mass production. And it’s important to use a consistent set of units. One of NASA’s worst black eyes was the Mars Climate Orbiter failure when one team used Imperial feet‑and‑pounds units and everyone else was on the metric system.”

“I gotta use both sets. Most of my baking supplies come in pounds, but the coffee beans and some of the flavorings come in kilograms. I gotta use my computer to resize a recipe.”

“That’s the thing with the metric system. It’s all about powers of ten. No dividing by 12 or is it 16 or even 5280 to get to a different size range — just move the decimal and you’re done. I don’t know why people have so much trouble with it.”

“It’s something new, Sy.”

“Yeah, but it’s not been new since the 1800s. It’s a long time since doctors prescribed by the scruple or minim. All there’s been for generations is milligrams and microliters. Gas prices being what they are these days I’m surprised the oil companies haven’t been pushing to sell by the liter — price per unit volume would drop by nearly a quarter.”

“I see ‘milli’ and ‘micro’ ornaments on one of those Christmas trees. Is that what they’re about?”

“That’s the ‘divide by a thousand’ tree. You already know ‘milli’ as the first cut‑down from grams or whatever the unit is. Divide by another thousand, you’ve got ‘micro’, which is one millionth or 10‑6. You’ve seen the ‘nano’ prefix by now — it’s 10‑9 and I like the nano‑nine connection. The ornaments on that tree display the prefixes for smaller and smaller subdivisions. The gold ones near the bottom are new this year. ‘Quecto’ is 10‑30, which would take you 30 digits if you wrote the number out.”

“So I guess the other tree is ‘multiply by a thousand.‘ Yup, there’s the ‘kilo’ for a thousand grams. Someone once told me I get about ten thousand beans in a kilogram bag.”

“Ten beans to a gram, then. That makes each bean a tenth of a gram or 100 milligrams. See how easy? Try figuring that in ounces.”

“Nice. Hey, I recognize ‘mega’ next to … a million. Counting’s hard without the commas in there.”

“Some people use spaces. You probably remember ‘giga’ and ‘tera’ from gigabytes and terabytes, you being a computer user.”

“Gigabucks, too. I read the news, you know. Politicians and CEOs play in the billions. But who needs numbers as big as ‘quetta’? That’s what, 1030?”

“Scientists and computer storage managers, mostly. Jupiter’s just shy of two quettagrams, and civilization’s on the path to generating a ronnabyte of data.”

~~ Rich Olcott