Author: rolcott

Born and raised in Chicago, schooled in WI and NJ and WI (again), one-time Chem professor, one-time Massage Therapist, one-time mainframe Performance Analyst, one-time husband of Val, two-time Daddy and two-time Grampa, long-time enthusiast of Science and careful thinking.

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

No Symphony on Mars

On By rolcottIn Astronomy: Planetary Science, Physics: Waves, Uncategorized2 Comments

“Evening, Jeremy, a scoop of your pistachio gelato, please. What’re you reading there?”

“Hi, Mr Moire. It’s ‘A City on Mars‘ by Kelly and Zach Weinersmith. One of my girlfriends read it and passed it along to me. She said it’s been nominated for a Hugo even though it’s non‑fiction and it argues against the kind of go‑to‑Mars‑soon planning that Mr Musk is pushing.”

“Is she right about the argument?”

“Pretty much, so far, but I’m not quite done. You get a clue, though, from the book’s subtitle — ‘Can we settle space, should we settle space, and have we really thought this through?‘ Here’s your gelato.”

“Thanks. Not just Mars, space also?”

“That’s right. It’s about the requirements and implications for people living in space and on the Moon and on Mars. The discussion starts with making and raising babies.”

“That first part sounds like fun.”

“Well, you’d think so, but apparently you need special equipment. Hard to stay in contact if there’s no gravity to key on. But that’s only the start of a problem cascade. Suppose the lady gets pregnant. The good news is in zero gravity it’s easy for her to move around. The bad news is we don’t know whether Earth gravity’s important for making babies develop the way they’re supposed to. Also, delivering a baby isn’t the only medical procedure that’d be a real challenge in zero‑g where you need to keep fluid droplets from bouncing around the cabin and into the air system.”

“Whoa. Hmm, never thought about it in this context before, but babies leak. Diapers can help, but babies burp up stuff along with the air. Yuck! Tears they cry in space would just stay on their eyes instead of rolling down cheeks. So … we’d need OB/GYN clinics and nurseries somewhere down a gravity well.”

“For sure, although no‑one knows whether even the Moon’s 1/6‑g is strong enough for good development. I know my little cousins burn up a lot of energy just running around. Can’t give a toddler resistance bands or trust it on a treadmill.”

“So we need an all‑ages gym down there, too, with enough room for locals and visiting spacers.”

“You’re coming round to the Weinersmiths’ major recommendation — don’t go until you can go big! Don’t plan on growing from a small colony, plan on starting with a whole city that can support everything you need to be mostly self‑sufficient.”

“So you’re young, Jeremy. Are you looking forward to being a Mars explorer?”

“I’ll admit all that rusty landscape reminds me of Navajoland, but I think I’d rather stay here. On Mars I’d be trapped in tunnels and domes and respirators and protective coveralls. I wouldn’t be able to just go out and run under the sky the way I was brought up to do.”

“Wouldn’t be able to do a lot of things. Concerts would sound weird, according to a paper I just read.”

“Sure, wind instruments wouldn’t work with bubble helmets. We could still have strings, percussion and electronics, though, right?”

“Sure you could have them. But it’s worse than that. Mars atmosphere is very different from Earth’s. Its temperature measured in kelvins is 25% colder. The pressure’s 99% lower. Most important, molecule for molecule Mars’ mostly‑CO2 atmosphere’s is 50% heavier than Earth’s N2‑O2 mixture. Those differences combine to muffle sounds so they don’t carry near as far as they would on Earth. Most sounds travel about 30% more slowly, too, but that’s where a CO2 molecule’s internal operation makes things weird.”

“Internal? I thought molecules in sound waves just bounced off each other like little billiard balls.”

“That’s usually the case unless you’re at such high pressures that molecules can start sticking to each other. CO2 under Mars conditions is different. If there’s enough time between bounces, CO2 can convert some of its forward kinetic energy into random heat. The threshold is about 4 milliseconds. A sound wave frequency longer than that travels noticeably slower.”

“Four milliseconds is 250 Hertz — that’s a middle B.”

“Mm-hm. Hit a cymbal and base drum simultaneously, your audience hears the cymbal first. Terrible acoustics for a band.”

~~ Rich Olcott

Marconi Would Be Proud

On By rolcottIn General: Fun Stuff, Physics: Quantum Mechanics, UncategorizedLeave a comment

A warmish Spring day.  I’m under a shady tree by the lake, waiting for the eclipse and doing some math on Old Reliable.  Suddenly there’s a text‑message window on its screen.  The header bar says 710‑555‑1701 . Old Reliable has never held a messaging app, that’s not what I use it for, but the set-up is familiar. I type in, Hello?

Hello, Mr Moire. Remember me?

Of course I do.  That sultry knowing stare, those pointed ears.  Hello, Lieutenant Baird.  It’s been a year.  What can I do for you?

Not Lieutenant any more, I’m back up to Commander, Provisional.

Congratulations. Did you invent something again?

Yes, but I can’t discuss it on this channel. I owe you for the promotion. I got the idea from one of your Crazy Theories posts. You and your friends have no clue but you come up with interesting stuff anyway.

You’re welcome, I suppose. Mind you, your science is four centuries ahead of ours but we do the best we can.

I know that, Mr Moire. Which is why I’m sending you this private chuckle.

Private like with Ralphie’s anti‑gravity gadget? I suggested he add another monitoring device in between two of his components. That changed the configuration you warned me about. He’s still with us, no anti‑gravity, but now he blames me.

Good ploy. Sorry about the blaming. Now it’s your guy Vinnie who’s getting close to something.

Vinnie? He’s not the inventor type, except for those maps he’s done with his buddy Larry. What’s he hit on?

His speculation from your Quantum Field Theory discussion that entanglement is somehow involved with ripples in a QFT field, ripples that are too weak to register as a particle peak. He’s completely backwards on entanglement, but those ripples—

Wait, what’s that about entanglement?

Entanglement is the normal state for quantized particles. Our 24th‑Century science says every real and virtual particle in the Universe is entangled with every other particle that shares the same fields. It’s an all‑embracing quantum state. Forget your reductionist 20th‑Century‑style quantum states, this is something … different. Your Hugh Everett and his mentor John Archibald Wheeler had an inking of that fact a century before your time, though of course they didn’t properly understand the implications and drew a ridiculous conclusion. Anyway, when your experimenting physicists say they’ve created an entangled particle pair, they’ve simply extracted two particles from the common state. When they claim to transmit one of the particles somewhere they’re really damping out the local field peak linked to their particle’s anti‑particle’s anti‑peak at the distant location and that puts an anti‑anti‑particle‑particle peak there. Naturally, that happens nearly instantaneously.

I don’t follow the anti‑particle‑anti‑peak part. Or why it’s naturally instantaneous.

I didn’t expect you to or else I wouldn’t have told you about it. The Prime Directive, you know. Which is why the chuckle has to be private, understand?

I won’t tell. I live in “the city that knows how to keep its secrets,” remember?

Wouldn’t do you any good if you did tell and besides, Vinnie wouldn’t think it’s funny. Here’s the thing. As Vinnie guessed, there are indeed sub‑threshold ripples in all of the fundamental fields that support subatomic particles and the forces that work between them. And no, I won’t tell you how many fields, your Standard Model has quite enough complexity to <heh> perturb your physicists. A couple hundred years in your future, humanity’s going to learn how to manipulate the quarks that inhabit the protons and neutrons that make up a certain kind of atom. You’ll jiggle their fields and that’ll jiggle other fields. Pick the right fields and you get ripples that travel far away in space but very little in time, almost horizontal in Minkowski space. It won’t take long for you to start exploiting some of your purposely jiggled fields for communication purposes. Guess what a lovely anachronism you’ll use to name that capability.

‘Jiggled fields’ sounds like communications tech we use today based on the electromagnetic field — light waves traveling through glass fibers, microwave relays for voice and data—

You’re getting there. Go for the next longer wavelength range.

Radio? You’ll call it radio?

Subspace radio. Isn’t that wonderful?

~~ Rich Olcott

Welcoming April

On By rolcottIn General: Fun Stuff, UncategorizedLeave a comment
Stan Laurel and Oliver Hardy, two of my favorite fools

The last time I posted in this blog on April 1 was in 2019. That time I was serious. This time I’m honoring a long and semi‑honorable Fool’s Day (or Fools’ Day) tradition in many countries across the world.

If you’re not familiar with the work of Laurel and Hardy, you’ve missed out on a lot of laughter. There’s a reason they had a long career with Hal Roach. Here are a few samples to get you started

Slapstick? Oh, yes, but world‑class slapstick. The 2018 biopic, Stan & Ollie with Steve Coogan and John C. Reilly, recreates some of their pieces as it follows the two after the peak of their career.

Want Science on April Fools’ Day? <HAW> April Fool!

Photo by Val Olcott

~~ Rich Olcott

Fields of Dreams

On By rolcottIn Cosmology, Physics: Quantum Mechanics, Physics: Waves, Uncategorized1 Comment

Vinnie takes a slug of his coffee. “So the gravitational field carries the gravitational wave. I suppose Einstein would blame sound waves on some kind of field?”

I take a slug of mine. “Mm-hm. We techies call it a pressure field. Can’t do solar physics without it. The weather maps you use when plotting up a flight plan — they lay three fields on top of the geography.”

“Lessee — temp, wind … and barometer reading. In the old days I’d use that one to calibrate my altimeter. You say those are fields?”

“In general, if a variable has a value at every point in the region of interest, the complete set of values is a field. Temperature and pressure are the simplest type. Their values are just numbers. Each point in a wind field has both speed and direction, two numbers treated as a single value, so you’ve got a field of vector values.”

“Oh, I know vectors, Sy. I’m a pilot, remember? So you’re saying instead of looking at molecules back‑and‑forthing to make sound waves we step back and look at just the pressure no matter the molecules. Makes things simpler, I can see that. Okay, how about the idea those other guys had?”

“Hm? Oh, the other wave carrier idea. Einstein’s gravitational waves are just fine, but the Quantum Field Theorists added a collection of other fields, one for each of the 17 boxes in the Standard Model.”

“Boxes?”

<displaying Old Reliable’s screen> “Here’s the usual graphic. It’s like the chemist’s Periodic Table but goes way below the atomic level. There’s a box each for six kinds of quarks; another half‑dozen for electrons, neutrinos and their kin; four more boxes for mediating electromagnetism and the weak and strong nuclear forces. Finally and at last there’s a box for the famous Higgs boson which isn’t about gravity despite what the pop‑sci press says.”

“What’s in the boxes?”

“Each box holds a list of properties — rest mass, spin, different kinds of charge, and a batch of rules for how to interact with the other thingies.”

“Thingies, Sy? I wouldn’t expect that word from you.”

“I would have said ‘particle‘ but that would violate QFT’s tenets despite the graphic’s headline.”

“Tenets? That word sounds more like you. What’s the problem?”

“That the word ‘particle‘ as we normally use it doesn’t really apply at the quantum field level. Each box names a distinct field that spreads its values and waves all across the Universe. There’s an electron field, a photon field, an up‑quark field, a down‑quark field, and so on. According to QFT, what we’d call a particle is nothing more than a localized peak in its underlying field. Where you find a peak you’ll find all the properties listed in its box. Wherever the field’s value is below its threshold, you find none of them.”

“All or none, huh? I guess that’s where quantum comes in. Wait, that means there could be gazillions of one of them popping up wherever, like maybe a big lump of one kind all right next to each other.”

“No, the rules prevent that. Quarks, for instance, only travel in twos or threes of assorted kinds. The whole job of the gluons is to enforce QFT rules so that, for instance, two up‑quarks and a down‑quark make a proton but only if they have different color charges.”

“Wait, color charge?”

“Not real colors, just quantum values that could as easily have been labeled 1, 2, 3 or A, B, C. There’s also an anti- for each value so the physicists could have used ±1, ±2, ±3, but they didn’t, they used ‘red’ and ‘anti‑red’ and so forth. And ‘color charge‘ is a different property from electric charge. Gluons only interact with color charge, photons only interact with electric charge. The rules are complicated.”

“You said ‘waves.’ Each of these fields can have waves like gravity waves?”

“Absolutely. We can’t draw good pictures of them because they’re 3‑dimensional. And they’re constantly in motion, of course.”

“How fast can those waves travel?”

“The particles are limited to lightspeed or slower; the waves, who knows?”

“Ripples zipping around underneath the quantum threshold could account for entanglement, ya’ know?”

“Maybe.”

~~ Rich Olcott

A Million Times Weaker Than Moonlight

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

Big Vinnie’s getting downright antsy, which is something to behold. “C’mon, Sy. We get it that sonication ain’t sonification and 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, but you said the Cosmic Hum is a sound, too. That’s a gravity thing, not molecules, right?”

“Not quite what I said, Vinnie. The Hum’s sound‑related, but it’s not ‘sound’ even by our extended definition.”

“Then what’s the connection?”

“Waves.”

“Not frames like always?”

“Not frames, for a change.”

“So it’s waves, but they go though empty space. Can’t happen like sound waves from molecules bumping into each other ’cause molecules are too small to have enough gravity do that when they’re so far apart. What’s carrying the waves?”

“Good question. Einstein figured out one answer. A whole cohort of mid‑20th‑century theoreticians came to a slightly different conclusion.”

“Okay, I’ll bite. What was Einstein’s answer?”

“Relativity, of course. Gravity’s the effect we see from mass deforming nearby space. Moving a mass drives corresponding changes in the shapes of space where it was and where it has moved to. The shape‑changes generate follow‑on gravitational effects that propagate outward over time. Einstein even showed that the gravitational propagation speed is equal to lightspeed.”

“Gimme a sec … Okay, that black hole collision signal LIGO picked up back in 2015, the holes lost a chunk of their combined mass all of a sudden. Quick drop in the gravity thereabouts. You’re saying it took time for the missing gravity strength to get noticed where we’re at. If I remember right, the LIGO people said the event was something like a billion lightyears away so that tells me it happened about a billion years ago and what the LIGO gadget picked up was space waves, right?”

“Right, but it wasn’t just the mass loss, it was the rapid and intense waggles in the gravitational field as those two enormous bodies, each 30 times as massive as the Sun, whirled around each other multiple times per second. The ever‑faster whirling shook the field with a frequency that swept upward to the ‘POP‘ when your mass‑loss happened. LIGO eventually picked up that signal. Einstein would say there’s no ‘action at a distance‘ in the collision‑LIGO interaction, because the objects acted on the gravitational field which acted on the LIGO system.”

“Like using a towel to pop someone in the locker room. The towel’s just transmi– ulp.”

“An admission of guilt if I ever heard one. Yes, like that, except a towel pop carries all the initial energy to its final destination. Gravitational waves spread their energy across the surface of an expanding sphere. The energy per unit area goes down as the square of the distance.” <keying a calculation on Old Reliable> “Suppose the collision releases 10 solar masses worth of energy, we’re a billion lightyears away, and the ‘POP‘ signal is delivered in a tenth of a second. We’d see a signal power … about a millionth as strong as moonlight.”

“Not much there.”

“Right, which is why LIGO and its kin have been such pernickety instruments to build and run. LIGO’s sensors are mirrors roughly a meter across. You get a million times more power sensitivity if your detector’s diameter is a mile across. That was part of the NANOGrav team’s strategy, but they went much bigger.”

“Yeah, that’s the multi-telescope thing, so NANOGrav faked a receiver the size of the Earth, like the Event Horizon Telescope.”

“Much bigger. Their receiver is the entire Milky Way. Instead of LIGO’s mirrors, NANOGrav’s signal generators are neutron stars a dozen or more miles wide scattered across the galaxy.”

“Gotcha, Sy. Two ways. Neutron stars are billions heavier than a LIGO mirror so they’d be less power‑sensitive, not more. Then, power is about moving stuff closer or farther but if I got you right these space waves don’t really do that anyway, right?”

“Right and right, Vinnie, but not relevant. What NANOGrav’s been watching for is pulsar beams being twitched by a gravitational wave. A waltzing black hole pair should generate years‑long or decades‑long wavelengths. NANOGrav may have found one.”

~~ Rich Olcott