Tag: Susan Kim

Xanax For Molecules

On By rolcottIn Physics: Entropy and Thermodynamics, UncategorizedLeave a comment

Vinnie plops down by our table at Cal’s Coffee. “Hi, guys. Glad you’re both here. Susan, Sy here says you’re an RDX expert so I got a question.”

“Not an expert, Vinnie, it’s just one of a series of compounds in one of my projects. What’s your question?”

“How come the stuff is so touchy but it’s not touchy? You can shoot a bullet into a lump of it, nothing happens, but set off a detonator next to it and WHAMO! Why do we need a detonator, and what’s in one anyway?”

“Sy, what sets off an H‑bomb?”

“An A‑bomb. You need a lot of energy in a confined region to crowd those protons enough that they fuse.”

“And what sets off an A‑bomb?”

“Hey I know that one, Susan, I saw the Oppenheimer movie. You need some kind of explosives going off just right to cram two chunks of plutonium together real fast so they do the BANG! thing instead of just melting. Wait! I see where you’re going — little explosions trigger big explosions, right?”

“Bravo! You’ve got the idea behind activation energy.”

“Geez, another kind of energy?”

“Yes and no, Vinnie. Enthalpy and its cousins are about the net change when something happens. We can use them to predict how a complex reaction will settle down, but they don’t tell us much about the kinetics, how fast things will happen. Think for a minute about those H‑bomb hydrogen atoms. What prevents them from fusing?”

“I guess under normal conditions they’re too far apart and even when they get close their electron clouds push against each other.”

<Sketching on a paper napkin> “Fair enough. Okay, here’s what the potential energy curve looks like, sorta. There’s hydrogen atom A over there at the right-hand end of the curve. B‘s a second hydrogen on the left and heading inwards. With me?”

“So far.”

“Right. Now, B comes roaring in with some amount of kinetic energy and hits the potential energy bump where those electron clouds overlap. If it has enough kinetic energy to overcome that barrier, it keeps on going. Otherwise it bounces back with the kinetic energy it had maybe minus some that A picked up in the recoil.”

“So the first barrier is the electron‑electron repulsion, but the potential dips in the middle where the clouds merge and that’s where molecules happen.”

“Right, Sy. But then there’s the second barrier as B‘s positive charge encounters A‘s. Inverse‑square law and all that, it’s an enormous hurdle. Visualize lots of Bs with different kinetic energies running up against that wall again and again until finally, if the pressure’s high enough, one gets past and the fusion releases more energy than the winning B had originally. The higher the wall, the fewer Bs hit As per unit time and the slower the reaction.”

“Looking at the before‑and‑afters, the reaction only happens if energy’s released, but how fast it goes is that barrier’s fault.”

“Perfect, Vinnie. Take RDX, for example. You’re right, it’s touchy. If you’ve got the pure stuff, never look at it cross‑eyed unless you’re behind a blast shield. Lots of energy released, very low energy of activation.”

“But like I said, you can shoot a gun at it, no effect.”

“That wasn’t pure RDX, it was probably some version of C‑4.”

“Yeah, C‑4, don’t know any of the details.”

“C‑4’s explosive is RDX, but it’s also got some plasticizer for that putty consistency, and a phlegmatizer. I love that word.”

“Phlegmatizer? That’s a new one for me.”

“It’s an additive to keep the explosive calm — phlegmatic, get it? — until it gets excited on purpose, which is the detonator’s job.” <scribbling on a stack of paper napkins> “Okay, here’s that same activation energy curve, an RDX particle on the right, and an incoming shock wave. The gray region is the phlegmatizer, usually paraffin or a heavy oil. Think of it as a shock absorber, absorbing or deflecting the shockwave before it can activate the explosive. A detonator’s designed to activate and erupt so quickly that its shock peak arrives before the phlegmatizer can spread it out.”

“Like they say, timing is everything.”

~ Rich Olcott

Tightening Up Fast And Loose

On By rolcottIn Physics: Entropy and Thermodynamics, UncategorizedLeave a comment

Cal brings out a fresh batch of scones. He’s tonging them onto the racks when I suddenly get a whiff of mocha latte. I glance back and there’s Susan Kim, grinning at me. “Hi, Sy. Grab your scone and a table. I have a bone to pick with you.”

A few moments later we’re seated. Cal’s coffee’s especially smooth today. “Okay, what’s the bone?”

“You’re playing fast and loose with your enthalpy definition. Yes, there’s change in temperature times entropy, enthalpy’s thermal component, and an expansion‑contraction component you called pressure‑volume. But it’s just sloppy to call what’s left ‘the chemical portion.’ What it is, really, is the combination of every other kind of energy something has that some process could extract. Chemical reactions are just one piece.”

“Strong words, coming from a chemist. What else should be packed in there?”

“Radioactivity, for one. It’s a heat source that doesn’t depend on chemical reactions. Atom for atom, a nuclear disintegration can yield millions of times more energy than a chemical reaction does. Trouble is, radioactive atoms only break down when they feel like it so the energy’s all random heat. I’m sure there’s a bunch of other non‑chemical ways to increase something’s apparent enthalpy.”

“Hmm. Challenge accepted. … It’s all about which process will extract some kind of energy from your something. How about the something’s a tightly‑wound spring? No, wait, that’s chemical, because the energy’s stored in stretched metal‑metal bonds.”

“No, I’ll accept spring tension because there’s no change in chemical composition during the unwind process. What’s another one?”

“Ah. Easy. Kinetic energy if the something’s flying through the air to hit something else.”

“Now you’re cooking. Gravitational potential energy if it’s falling down. Oh, suppose it’s magnetized and goes through a conductive loop on the way down?”

“Nope, doesn’t count. The object’s kinetic energy would produce a jolt of electrical potential in the loop, but it’s own magnetization wouldn’t change. Nice, that distinction sharpens the point — what you count as enthalpy’s third component depends on which change process you’re talking about. If there’s no chemical change, then the chemical part of the internal component of the enthalpy change is zero. In the early days of thermodynamics, for instance, everyone was working on steam. Water may corrode your equipment over the long term, but otherwise it’s just hot water molecules becoming not‑as‑hot water molecules and there’s no change in internal energy. The only energy terms you have to think about are pressure‑volume and temperature‑entropy. That’s why they defined it that way.”

“Which one wins?”

“Hmm?”

“You’ve pared enthalpy changes down to just two kinds of energy. I’ve got to wonder, which one has the bigger contribution?”

<pulls up a display on Old Reliable> “This is just for the water‑steam system, mind you. Vinnie was surprised. It’s all based on specific heat measurements so visualize one kilogram of liquid water.”

“A liter, right.”

“The line labeled ‘Mechanical’ is the amount of energy you’d get by expanding that kilogram from 0°C up to the temperatures laid out on the x‑axis. No significant expansion up near boiling temperature, then it follows the Ideal Gas Law, PV=nRT. At atmospheric pressure and in this temperature range the expansion relative to 0°C runs about 200 kilojoules per kilogram.”

“And the ‘Thermal’ line?”

“That’s lab‑measured heat capacity values I pulled from the CRC Handbook, each multiplied by the corresponding temperature in kelvins. That’s the amount of energy our kilogram of water molecules holds just by being at the temperature it’s at. The gas makes a nice straight line, at least in the range before heat shatters the molecules.”

“That’s what, fifteen or sixteen times more energy than the mechanical part? Wow! You know, back in Physical Chemistry class they just threw around lots of confusing thermodynamics formulas but never put numbers to them. I had no idea the entropy effect could just swamp whatever else.”

“Numbers do make a difference.”

“This clarifies something I didn’t understand back then. Entropy’s about randomness, right, and a gas molecule can be in more locations in a large volume than in a small one. V=nRT/P says volume rises linearly with temperature and that’s the linear rise in your chart.”

~ Rich Olcott

The Little Engine That Cooled

On By rolcottIn Physics: Entropy and Thermodynamics, UncategorizedLeave a comment

“Chemical potential energy is something else, Sy. You’ve got like this lump of putty just sitting there and suddenly WHAMO! Kinetic energy all over the place.”

“Sounds like you’ve been playing with explosives, Vinnie.”

“Sorta. Some of the Specials down at the base let me watch a couple of their C-4 practice shots. You know anything about C-4?”

“A little, like what it’s made of. Susan Kim’s interested in the main ingredient for some chemical reason. She calls it RDX, drew me a picture of it once. Nice symmetrical molecule loaded with nitrogen and carbon atoms just itching to fly away as a dozen separate gas molecules. Funny, how such violent stuff can be so relaxed until just the right thing sets it off. Like some people I know.”

Combustion of an RDX molecule

“Ouch. Yeah, it happens, but I’m mellowing, okay? A dozen fragments per molecule, got it. Hey, what chemical is ‘NOx‘?”

“Could be nitrous oxide N2O, or nitric oxide NO, or some combination depending, which is why there’s no number in the equation in front of oxygen’s O2. Combustion is messy.”

“Yeah, enthalpy all over the place! Those separate gas molecules spread out to a way bigger volume than the solid molecule used up. Lotsa pressure‑volume work there, right?”

“True, but gas expansion’s only one factor in an RDX discharge. Did the guys at the base mention that if you detonate that putty when it’s spread thin it can burn through an I‑beam?”

“So there’s heat, too. Can’t be much stacked up against the expansion.”

“Don’t be so sure. I’m not up on RDX thermochemistry. I never asked Susan and I don’t know whether she or anyone knows the breakout. It’s hard to do a precision measurement on an explosion, even if you do it in milligram quantities. I’ve got a good substitute for that, though. Water’s way simpler and much more thoroughly studied.”

“How is water a substitute? It doesn’t explode.”

“True, but it boils. No changes in molecular bonding, so enthalpy’s chemical part isn’t a factor. Carnot taught us to figure the pressure‑volume and thermal parts separately. Suppose you load a liter of water into a cylinder‑piston arrangement that stays at one atmosphere pressure. Get it up to boiling temperature then measure the energy input while the water boils away. The water absorbs energy while it turns to steam, right, even though there’s no change in temperature.”

“It stays at 212°?”

“212°F is 100°C or 373 K, stays steady provided the pressure stays at one atmosphere, 14.7 psi or 101325 pascals, whichever units you want to use. Pressure and temperature work together when it comes to phase changes. Anyway, the only way your rig can maintain that exact pressure is to do some kind of work, lifting a weight or something, until the cylinder’s final volume above the piston is 1705 liters. That’ll be 172 kilojoules of useful work.”

“Big cylinder.”

“Granted, but we supposed a liter of water. Scale the equipment to handle just a milliliter of water and the swept volume’s down to 1.7 liters. Neat how the metric system works. But now you’ve got a design decision to make. You can release the steam with a loud CHUFF that carries away 92% of the energy you put into it—”

“That’s no good.”

“— or you can run it through a condenser that preheats the feed water for the next cycle. Saves a lot of fuel that way.”

“That’d be my choice.”

“Mm-hm. That was Watt’s crucial improvement on Newcomen’s design. Funny thing, though. Both guys are credited with ‘inventing the steam engine’ but neither one built a device like the engines we’re used to, ones that develop power by pushing on a piston. The big demand in their day was pumping water out of mine shafts. Newcomen and Watt built vacuum gadgets.”

Watt’s steam pumping engine

“I had a well once. You can’t pull water up more than about 35 feet.”

“Right. Vacuum pumping is limited. Unfortunately, so was manufacturing technology in Watt’s time. Making a piston and cylinder that would fit together efficiently over a wide temperature range was a big challenge.”

“Their engines sucked, huh?”

~ Rich Olcott

New (Old) Word: Frigorific!

On By rolcottIn Physics: Entropy and Thermodynamics, UncategorizedLeave a comment

A quiet morning at Cal’s Coffee. I’m sipping my morning mud when Susan Kim bustles to my table, mocha latte in hand. “There you are, Sy. I loved your posts in tribute to the well‑thumbed copy of the CRC Handbook on my desk.”

“Glad you enjoyed them.”

“Your Rumford stuff made it even better because I did a class report on him once so I caught your ‘frigorific‘ reference. What do you know about the background to that?”

“Not much. Didn’t sound like a real word when I ran across it.”

“Oh, it’s a real word but it has a technical meaning now that it didn’t in Newton’s time. Back then it was only about making something cold. These days we also use the word for a mixture that maintains a dependable cold temperature. Liquid water and ice, for instance, stays at 0°C as long as there’s still ice in the cold bath. I used to use an ammonium chloride/water frigorific when I needed something down around -15°C. Now of course I use a benchtop refrigerator.”

“Rumford would have liked that. What were the ‘frigorific rays‘ he got all excited about?”

“Long story but there’s a couple of fun twists. Background first. At the end of the 1700s there was a <grin> heated debate about heat. The phlogiston theory was dead by that time but people still liked the idea that heat was a material fluid. It addressed some chemical puzzles but heat transmission was still mysterious. Everyone knew that a hot object gives off heat by radiation, that the radiation travels in straight lines and that it’s reflected by metal mirrors.”

“Right, the Greeks are supposed to have used huge sun‑focusing mirrors to burn up attacking Roman ships.”

“Maybe. Anyhow, those properties connected heat with light. However, a pane of glass blocks radiated heat, at least until the glass gets hot. People argued this meant heat and light weren’t connected. About 1790 a group of physicists loosely associated with the Academy of Geneva dove into the fray. Rumford was in the group, along with Prévost, Saussure and his student Pictet. They had lots of fun with heat theories and experiments. One of Pictet’s experiments lit Rumford’s fire, so to speak.”

“Good one.”

<smile> “It’s a fairly simple setup that a high school science teacher could do. Pictet hung a concave metallic mirror facing down from the ceiling of a draft‑free room. He placed another concave metallic mirror at floor level immediately beneath it, facing upward. He probably used spherical mirrors which are easy to make, but they could have been elliptical or parabolic sections. Anyhow, he put a thermoscope at the upper mirror’s focal point and a hot object at the lower focal point. Sure enough, the upper focal point got hotter, just as you’d expect.”

“No great surprise, the Greeks would have expected that, too.”

“The surprise happened when he put a cold object in there. The thermoscope’s droplet moved in the cold direction.”

“Wait, like anti‑infrared?”

“That’s the effect. Wave‑theory supporter Rumford took that thought, called it ‘frigorific radiation‘ and ran with it. He constructed a whole thesis around cold waves and heat waves as symmetric partners. He maintained wave intensity, both kinds, increases with temperature difference. Our heat sources are hundreds or thousand of degrees hotter than we are but our cold sources are at most a few dozen degrees colder. By his theory that’s why cold wave phenomena are masked by heat waves.”

“Give me a minute. … Ah, got it. The very meaning of a focal point is that all waves end or start there. A cold object at the sending station emits much less infrared than the warm object did. The thermoscope bulb now gets less than it emits. With less input from below its net energy drops. It chills.”

“Nice, Sy. Now for the other twist. Rumford published his theory in 1805. Herschel had already identified infrared radiation in the Sun’s spectrum in 1800. Two strikes against Herschel, I guess — he was British and he was an astronomer. Continental physicists wouldn’t bother to read his stuff.”

~ Rich Olcott

A.I. and The Ouroboros Effect

On By rolcottIn General: Serious Stuff, UncategorizedLeave a comment

The Acme Building Science and Pizza Society is meeting again around the big table near the kitchen in Eddie’s Pizza Place. It’s my deal so I set the next topic. “Artificial Intelligence.” There’s some muttering but play starts.

Cal has first honors. “Not my favorite thing. I hadda change my name ’cause of A.I., f’crying out loud.”

Eddie antes up a chip. “But Cal, your astronomy magazines are loaded with new discoveries that some A.I. made rummaging through godzillabytes of big telescope data. Train an A.I. on a few thousand normal galaxies and then let it chase through the godzillabytes. It says ‘Here’s a weird one‘ and the human team gets to publish papers about a square galaxy or something.”

Susan chips in. “What about all the people who’ve been saved from cancer because an A.I. found bad cells while screening histology images?”

Kareem folds. “Not much A.I. in Geology yet. Our biggest Big Data project these days is whole‑Earth tomography. That uses pretty much all the computer time we can get funds for. A.I.’s Large Language Models soak up all the research money.”

Vinnie raises by a chip. “I use autopilot a lot when I’m flying, but that’s up in the air, Great Circle point‑to‑point and no worries about pedestrian traffic. Autopilot in a car? Not for me, thanks — too many variables and I’ve seen too many crazy situations you couldn’t predict. Black ice in the winter, roadwork and bicyclists the rest of the year — I want to be able to steer and brake when I need to.”

Susan grins. “Are you a stick‑shift purist, Vinnie?”

“Naw, automatic transmissions are okay these days and besides my car uses electric motors and doesn’t even have a transmission. Lots of torque at low revs and that’s the way I like it. What about you, Cathleen? Got any A.I. war stories?”

Cathleen calls Vinnie’s raise. “A few. One thing I’ve learned — chatbots have a limited working memory. I once asked a bot to list Jupiter’s 35 biggest moons in decreasing order of size. It got the first 24 in the right order, then some more moons out of order and two of them were moons of Saturn. So ‘trust but verify‘ like the man said. Sy, you do a lot of writing. What’s your experience?”

I call Cathleen’s raise. “Mixed. I’m a generalist so I have to read a lot of papers or at least be aware of them. Summarizer bots do a decent job on some reports but miss badly when it comes to tying together material that’s not already well organized. Probably comes from that working memory limitation you noticed, Cathleen. The other problem I’ve seen doesn’t apply so much to technical work but it’s a killer for essays and fiction that have anything to do with interactions between people.”

“I’ve seen that, too. No soul.”

“Soul’s the word I’ve been looking for, Kareem. The bots are good at picking up styles and ‘who said what‘ surface material, but they fail completely at emotional subtext, the ‘why‘ that’s the actual thread of a conversation. Subtext is why we read good novels. From what I’ve been seeing recently, it’s not going to get any better.”

“Nothing does, I’m starting to think.”

“C’mon, Cal, your coffee’s improved since the city put in better water pipes. On the other hand, you owe the pot a bet.”

“Sorry. I’m still in, okay?” <sound of chips clinking> “So why’s A.I. not gonna get better? I keep reading how different ones passed tougher tests.”

“Well, that’s the thing. If you’re reading about it online, the bots are, too. What they read goes into their training database. Those impressive test scores may just be the result of inadvertent cheating — but the software’s so opaque that its developers simply don’t know whether or not that’s true. Just another case of the Ouroboros Effect.”

Eddie and Susan meet Cal’s bet, then Vinnie goes all‑in and shows his three queens. “Ouroboros, Sy?”

“The Norse World Snake that eats its tail. Bogus A.I.‑generated output used as A.I. input yields worse output. That’s a loss, not a gain. Unlike here where my four kings take the pot.”

“Geez, Sy, again?”

~~ Rich Olcott

The Ultimate Pinhole Camera

On By rolcottIn Astronomy: Techniques, Physics: Black Holes and Relativity, UncategorizedLeave a comment

Neither Kareem nor I are much for starting conversations. We’re more the responder type so the poker hands we dealt went pretty quickly. Cathleen had a topic, though. “Speaking of black holes and polarized radio waves, I just read a paper claiming to have developed a 3‑dimensional movie of an event wider than Mercury’s orbit, all from the flickering of a single pixel.”

Eddie bets big, for him. Ten chips. “That’s a lot to ask from just a dot. And what’s polarization got to do with it?”

Cal folds but pipes up anyway. “What was the event?”

“You know Sagittarius A*, the supermassive black hole in the middle of our galaxy?”

“Yeah, one of those orange‑ring pictures.”

“Mm‑hm. Based on radio‑wave emissions from its accretion disk. That image came from a 2‑day Event Horizon Telescope study in 2017. Well, four days after that data was taken, the Chandra satellite observatory saw an X‑ray flare from the same region. The ALMA radio telescope team immediately checked the location. ALMA has excellent signal‑to‑noise and time‑resolution capabilities but it’s only one observatory, not world‑wide like the EHT. The EHT can resolve objects a hundred thousand times closer together than ALMA’s limit. But the team did a lot with what they had.”

Vinnie tends to bet big, maybe because he’s always skeptical. Fifteen chips. “You said ‘claiming‘ like there’s doubt. People don’t trust the data?”

“In science there’s always doubt. In this case, no‑one doubts the data — ALMA’s been providing good observations for over a decade. The doubt’s in the completely new AI‑driven data reduction technique the team used. Is what they did valid? Could their results have been affected by a ‘hallucination’ bug?”

Vinnie doesn’t let go. “What did they do, what have people been doing, and what’s hallucination?”

Susan reluctantly shoves fifteen chips into the pot. “Hallucination is an AI making up stuff. I just encountered that in a paper I’m reviewing. There’s a long paragraph that starts off okay but midway it goes off on a tangent quoting numbers that aren’t in the data. I don’t believe the submitting authors even read what they sent in.”

Kareem drops out of the betting but stays in the conversation. “For a lot of science, curve‑fitting’s a standard practice. You optimize a model’s parameters against measured data. X‑ray crystallography, for example. The atoms in a good crystal are arranged in a regular lattice, right? We send a narrow beam of X‑rays at the crystal and record the intensity reflected at hundreds of angles by the atoms in different lattice planes. Inside the computer we build a parameterized model of the crystal where the parameters are the x‑, y‑ and z‑coordinates of each atom. We have computer routines that convert a given set of configuration parameters into predicted reflection intensity at each observation angle. Curve‑fitting programs cycle through the routines, adjusting parameters until the predictions match the experimental data. The final parameter values give us the atomic structure of the crystal.”

“There’s a lot of that in astrophysics and cosmology, too. This new AI technique stands that strategy on its head. The researchers started with well‑understood physics outside of the event horizon — hot rotating accretion disk, strong magnetic field mostly perpendicular to that, spacetime distortion thanks to General Relativity — and built 50,000 in‑computer examples of what that would look like from a distance.”

“Why so many?”

“The examples had to cover one or two supposed flares of different sizes and brightness at different points in their orbits, plus noise from the accretion disk’s radiation, all from a range of viewpoint angles. Mind you, each example’s only output was a single signal intensity and polarization angle (that’s two dimensions) for that specific set of disk and flare configuration parameters. The team used the example suite to train an AI specialized for assembling 2‑dimensional visual data into a 3‑dimensional model. The AI identified significant patterns in those 50,000 simulated signals. Then the team confronted the trained AI with 100 minutes of real single‑pixel data. It generated this…”

Click through to video, from Levis, et al.

“Curve‑fitting but we don’t know the curves!”

“True, Sy, but the AI does.”

“Maybe.”

~ Rich Olcott

A Non-political Polarizing Topic

On By rolcottIn Astronomy: Techniques, Physics: Black Holes and Relativity, Physics: Waves, UncategorizedLeave a comment

Vinnie gets the deck next, but first thing he does is plop a sheet of paper onto the table. “Topic is black holes, of course. Everybody’s seen this, right?”

“Sure, it’s the new view of the Milky Way’s super-massive black hole with the extra lines. So deal already.”

“Hold your horses, Cal.” <Vinnie starts dealing.> “I’m looking for explanations. Where’d those lines come from? They swirl across the accretion disk like so much rope, right? Why aren’t they just going straight in orderly‑like? The whole thing just don’t make sense to me.”

Susan bets a few chips. “I saw a similar pop‑sci article, Vinnie. It said the lines trace out polarization in the light waves the Event Horizon Telescope captured. Okay, radio waves — same thing just longer wavelength. Polarized radio waves. I’ve measured concentrations of sugar and amino acid solutions by how much the liquid rotates polarized light, but the light first went through a polarizing filter. How does a black hole make polarized waves?”

Kareem matches Susan’s bet. “Mm‑hm. We use polarized light passing through thin sections of the rocks we sample to characterize the minerals in them. But like Susan says, we don’t make polarized light, we use a filter to subtract out the polarization we don’t want. You’re the physicist, Sy, how does the black hole do the filtering?”

Plane‑polarized electromagnetic wave
 Electric (E) field is red
 Magnetic (B) field is blue
(Image by Loo Kang Wee and Fu-Kwun Hwang from Wikimedia Commons)

My hand’s good so I match the current ante. “It doesn’t. There’s no filtering, the light just comes out that way. I’d better start with the fundamentals.” <displaying Old Reliable> “Does this look familiar, Vinnie?”

“Yeah, Sy, you’ve used it a lot. That blue dot in the back’s an electron, call it Alice, bobbing straight up and down. That’s the polarization it’s puttin’ on the waves. The red lines are the force that another electron, call it Bob, feels at whatever distance away. Negative‑negative is repelling that so Bob goes down where the red line goes up but you get the basic idea.”

“The blue lines are important here.”

“I’m still hazy on those. They twist things, right?”

“That’s one way to put it. Hendrik Lorentz put it better when he wrote that Bob in this situation experiences one force with two components. There’s the red‑line charge‑dependent component, plus the blue‑line component that depends on the charge and Bob’s motion relative to Alice. If the two are moving in parallel—”

“The same frame, then. I knew frames would get into this somehow.”

“It’s hard to avoid frames when motion’s the subject. Anyway, if the two electrons are moving in parallel, the blue‑line component has zero effect. If the two are moving in different directions, the blue‑line component rotates Bob’s motion perpendicular to Alice’s red‑line polarization plane. How much rotation depends on the angle between the two headings — it’s a maximum when Bob’s moving perpendicular to Alice’s motion.”

“Wait, if this is about relative motion, then Bob thinks Alice is twisting, too. If she thinks he’s being rotated down, then he thinks she’s being rotated up, right? Action‑reaction?”

“Absolutely, Vinnie. Now let’s add Carl to the cast.”

“Carl?”

Alice and Bob’s electromagnetic interaction
begets motion that generates new polarized light.

“Distant observer at right angles to Alice’s polarization plane. From Carl’s point of view both electrons are just tracking vertically. Charges in motion generate lightwaves so Carl sees light polarized in that plane.”

Cathleen’s getting impatient, makes her bet with a rattle of chips. “What’s all this got to do with the lines in the EHT image?”

“The hole’s magnetic field herds charged particles into rotating circular columns. Faraday would say each column centers on a line of force. Alice and a lot of other charged particles race around some column. Bob and a lot of other particles vibrate along the column and emit polarized light which shows up as bright lines in the EHT image.”

“But why are the columns twisted?”

“Orbit speed in the accretion disk increases toward its center. I’d bet that’s what distorts the columns. Also, I’ve got four kings.”

“That takes this pot, Sy.”

~~ Rich Olcott

New Volcano, Old Crater

On By rolcottIn Astronomy: Planetary Science, UncategorizedLeave a comment

Now Eddie’s dealing the cards and the topic choice. “So I saw something on TV about a new volcano on Mars. You astronomy guys have been saying Mars is a dead planet, so what’s with a new volcano? Pot’s open.”

Vinnie’s got nothing, throws down his hand. So does Susan, but Kareem antes a few chips. “I doubt there’s a new volcano, it’s probably an old one that we just realized is there. We find a new old caldera on Earth almost every year. Sy, I’ll bet your tablet knows about it.”

I match Kareem’s bet and fire up Old Reliable. A quick search gets me to the news item. “You’re right, Kareem, it’s a new find of an old volcano. This article’s a puff‑piece but the subject’s in your bailiwick, Cathleen.”

Cathleen puts in her bet and pulls out her tablet. “You’re right, Kareem. It’s a volcano we all saw but no‑one recognized until this two‑person team did. Here’s a wide‑angle view of Mars to get you oriented. North is up top, east is to the right just like usual.”

“Gaah. Looks like a wound!”

“We’ll get to that. The colors code for elevation, purple for lowlands up through the rainbow to red, brown and white. Y’all know about Olympus Mons, the 22‑kilometer tallest volcano in the Solar System, and there’s Valles Marineris, at 4000 kilometers the longest canyon. The Tharsis bulge is red‑to‑pink because it’s higher than most all the rest of the planet’s surface. Do you see the hidden volcano?”

“It’s hard to tell the volcanos from the meteor craters.”

“Understandable. Let me switch to a closer view of the canyon’s western end. This one’s in visible light, no color‑coding games. The middle one of the three Tharsis volcanos is to the left, no ginormous meteor craters in the view. Noctis labyrinthus, ‘the Labyrinth of Night.’ is that badlands region left of center. Lots of crazy canyons that go helter‑skelter.”

“That’s more Mars‑ish, but it’s still unhealthy‑looking.”

“It is a bit rumpled. Do you see the volcano?”

“Mmm, no.”

“This should help. It’s a close-up using the elevation colors to improve contrast.”

“Wow, the area inside that circle sure does look like it’s organized around its center, not higgledy-piggledy like what’s west of it. That brown image had something peaky right about there. What’s ‘prov’?”

“Good eye, Susan. The ‘prov’ means ‘provisional‘ because names aren’t real until the International Astronomical Union blesses them. The peak is nine kilometers high, almost half the height of Olympus Mons. The concentric array of canyons and mesas around it certainly make it look like a collapsed and eroded volcano. But IAU demands more evidence than just ‘look like.’ Using detailed spectroscopic data from two different Mars orbiters, the team found evidence of hydrated minerals plus structural indications that their proposed volcano either punched through a glacier or flowed onto one. Better yet, the mesas all tilt away from the peak, and the minerals are what you’d expect from water reacting with fresh lava.”

“Did they use the word ‘ultramafic‘?”

“I don’t think so, Kareem, just ‘mafic‘.”

“From underground but not deep down, then.”

“I suppose.”

Cal bets. “You said we’d get back to wounds. What was that about?”

“Well, just look at all that mess related to the Tharsis bulge — higher than all its surroundings, massive volcanos nearby, the Noctis badlands, Valles Marineris that doesn’t look water‑carved but has that delta at its eastern end. Why is all of that clustered in just one part of the planet? Marsologists have dozens of hypotheses. My own favorite centers on Hellas basin. It’s the third largest meteor strike in the Solar System and just happens to be almost exactly on the opposite side of Mars.”

Eddie looks a bit gobsmacked. “A wallop like that would carry a lot of momentum. Kareem, can a planet’s interior just pass that along in a straight line?”

“Could be, depending. If it’s solid or high‑viscosity, I guess so. If it’s low‑viscosity you’d get a doughnut‑shaped circulatory pattern inside that’d turn the energy into heat and vulcanism. How long was Mars cooling before the hit?”

“We don’t know.”

Cal’s pair of jacks apologetically takes the pot.

~~ Rich Olcott

Soggy Euclid

On By rolcottIn Astronomy, UncategorizedLeave a comment

It’s Cal’s turn to deal the cards and topic. “Water, water everywhere, especially where you wouldn’t expect it.”

Eddie bets a few chips. “Say what, Cal?”

“Oh, this article in one of my Astronomy magazines, says Euclid has an ice problem.”

“None of Euclid’s problems are nice. I barely got out of Geometry class alive.”

“Not that Euclid, Eddie. The European Space Agency’s Euclid space telescope that’s gonna catalog whatever it can see in a third of the sky. They’re looking to pick up everything out to 10 billion lightyears. S’posed to help us chase down dark energy, get a better handle on really big structures and voids, stuff like that. Anyhow, it’s in a potato‑chip orbit around the Earth‑Sun L2 point like JWST does but twice as far out. The ESA engineers noticed that Euclid‘s readings of some calibration stars were dropping and they figured out it was ice getting in the way.”

“Ice? In space?”

“Yeah, that’s what I said. Turns out all our space missions bring water out with ’em even if they don’t want to.”

Vinnie’s bet doubles the pot. “Ain’t gonna happen. Every ounce of payload gotta have a good excuse or they don’t let it ride.”

“No, really. This ain’t payload, it’s like a stowaway. Mostly in the thermal insulation which has a lot of surface area inside with nooks and crannies where water molecules can stick. Makes no difference to most missions, but when you’ve got world‑class optics that you’re pushing to their limits, a layer of ice a few dozen molecules thick in the wrong place can hurt.”

“Okay, I get there’s problems if the ice is in the optics but you said it was in the insulation. And what’s it even doing there in the first place? If they know it’s gonna be a problem they can just bake it out during construction.”

Chemist Susan chucks a handful of chips into the pot. “Water molecules are small and sneaky. They always surprise you, especially when you don’t want them to. When they’re frozen‑solid ice you’d think they’d stay there, right? Oh, no, they evaporate without going through a liquid phase which lets them migrate around. It’s called sublimation. And do they migrate — just try to keep them out of somewhere. Pour absolute ethanol through humid air, it’s not absolute any more. Dry solids? If the substance has any surface oxygens you’re guaranteed to have water molecules hanging onto them even after you bake the stuff. So, Vinnie — that insulation wrap in the telescope? If it ever saw humidity the fibers are carrying water that could migrate to the optics.”

“Oh yeah, there’ll be humidity. Okay, Baikonur’s pretty much in the middle of a near‑desert, but the Guiana Space Center that France uses is right by the ocean and have you ever looked at a map of Cape Canaveral? That insulation’ll be soggy enough to spew water molecules onto the optics even at space temperatures. C’mon, Kareem, you gonna bet or what?”

“I’m deciding whether to talk about watery moons or the deep‑down Earth water we’re discovering. Jupiter’s moon Europa, for instance. We now know it has a kilometers‑thick shell of ice surrounding an ocean with twice as much water as our oceans put together. Meanwhile,” <meets Susan’s bet> “there’s another huge ocean beneath our feet.”

“Not our feet. This place is built on bedrock.”

“Think below the bedrock, Cal. We live on top of crust, maybe a couple dozen kilometers thick, floating on molten magma. You guys know about subduction, right, where chunks of sea-bottom crust are forced under the edges of continental crust. The further down you go, the hotter things get. The sea‑bottom stuff eventually melts to form lighter magma that ultimately rises to make volcanoes. Thing is, the sinking crust drags water with it, either in cracks or as water of crystallization. A melting chunk releases its water into a kilometers‑thick layer of steamy silicate slurry roughly 400 kilometers below us. That water ‘rains’ upward into our oceans, completing the cycle. Full house, queens and aces. Any challengers?”

Kareem’s surprisingly impatient for a geologist. Nobody counters so the pot’s his. Eddie gets next deal.

~~ Rich Olcott

Sounds, Harsh And Informative

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

Vinnie’s frowning. “Wait, Sy. I get how molecules bumping into each other can carry a sound wave across space if the frequency’s low enough and that can maybe account for galaxies having spiral arms. So what’s that got to do with the Sonication Project?”

Now Jeremy’s frowning. “What’s sonication got to do with Astronomy? One of my girl friends uses sonication in Biology lab when she’s studying metabolism in plant cells.”

“Whoa! Sonification, not sonication — they could have called it soundify‑cation but sonification‘s classier. ‘Sonication‘ uses high‑intensity ultrasound to jiggle a sample so roughly that cell walls can’t take the stress. They break open and spill the cell’s internal soup out where your friend’s probes can get to it. Tammy, the chemist down the hall from my lab, uses sonication, too.”

“Whoa, Susan, wouldn’t sonication break up molecules?”

“Depends on the frequency and intensity, Vinnie. Sonication can mess up big floppy proteins and DNA, but chemists who play with little peptides and such don’t care. Tammy does solid‑state chemistry. She’s looking for superconductors and she actually does want to break things. The field’s hot category these days is complex copper oxides doped with other metals. You synthesize those compositions by sintering a mix of oxide powders. To maximize contact for a good reaction you need really fine‑grained powders. Sonication does a great job of shattering brittle oxide grains down to bits just a few‑score atoms wide. But Tammy’s technique is even more elegant than that.”

“Elegant sneezes from the powder?”

Susan wallops my shoulder. “No, Sy, the powders are so small they’d be a lung hazard and some of them are toxic. Everything’s done behind respiratory protection.” <Susan doesn’t joke about lab safety.> “There’s evidence that some of these materials are only superconductive if they have the right kind of layered structure. Turns out that if Tammy has her sonicator setup just right when she preps a sample for sintering, the sound wave peaks and valleys inside the machine make the shattered particles settle out in interesting layers.”

“Like Chladni figures.”

“Oh, you know about them.”

“Yeah, I wrote about them a few years ago. Waves do surprising things.”

The Bullet Cluster (1E 0657-56)
Sonification Credit: NASA/CXC/SAO/K.Arcand,
SYSTEM Sounds (M. Russo, A. Santaguida), based on X-Ray image by NASA/CXC/CfA/M.Markevitch,
Optical and lensing map: NASA/STScI, Magellan/U.Arizona/D.Clowe,
Lensing map: ESO WFI

Vinnie’s getting impatient. “So what’s sonification then?”

Tinkly music bursts from Cathleen’s tablet. “This one’s listenable, Susan, and it’s a nice demonstration of what sonification’s about and how arbitrary it can be. You start with complicated multi‑dimensional data and use some process to turn it into audible signals. The process algorithm can use any sound characteristics you like — loudness, pitch, timbre, whatever. This example started with the famous Bullet Cluster image that most people accept as the first direct confirmation of dark matter. All the white‑ish thingies are galaxies except for the ones with pointy artifacts — those are stars. The pink haze is X‑ray light from the same region. The blue haze comes from a point‑by‑point assessment of how badly the galaxy images have been distorted by gravitational lensing — that’s an estimate of the dark matter mass between us and that region of sky. Got all that?”

“And that vertical line is like a scan going across the picture?”

“It’s not like a scan, it is a scan. Imagine a collection of tiny multi‑spectral cameras arranged along a carrier bar. As the bar travels across the picture, each camera emits three signals proportional to the amount of white, pink and blue light it sees. If you look close, just to the right of the line, you’ll see moving white, red and blue line‑charts of the respective signals.”

“That’s fine, but what’s with the sound effects?”

“The Project’s sonification processing generated hiss and rumble sounds whose loudness is proportional to the red and blue signals. Each white‑ish peak became a ping whose pitch indicates position along that bar.”

“Why go to all that trouble?”

“The sounds encode the picture for vision‑challenged people. Beyond that, the Project participants hope that with the right algorithms, their music will reveal things the pictures don’t.”

“They should avoid screamy sounds.”

~~ Rich Olcott