Tag: Cathleen

Dark Glasses

On By rolcottIn Physics: Light and Relativity, Uncategorized2 Comments

My office door THUMPs as Richard Feder barrels in. Vinnie’s half out of his chair with his fists balled up but he settles back down when he sees who it is. “Moire, I gotta question.”

“Afternoon, Mr Feder. What brings you to the 12th floor of the Acme Building?”

“My dentist’s up here. They gave me these really dark glasses for when they aimed a bright light in my mouth to harden something in there so I wondered why’re they so dark an’ what about those glasses that can’t make up their minds?”

“Well, Mr Feder, as usual you’ve asked a jumbled question. Let’s see. The answers all boil down to what light is made of and what the glasses are made of.”

“I thought it was photon particles, Sy. The light, I mean.”

“It is, Vinnie, but photons only act like particles when they’re emitted and when they’re absorbed. In between, they act like waves. Dark glasses are all about photons as waves. The simplest case is the plain dark glasses.”

“Yeah, Moire, simple’s good.”

“They’re black because they’ve been doped with black chemicals. If your glasses are actually made of glass, the manufacturer probably dumped iron and sulfur into the melt. When heated those elements combine to form black iron sulfide particles spread throughout the mass. If the glasses are plastic, the manufacture mixed black dye into the formula. Either way, the more dopant added, the blacker the product and the fewer waves make it through the lens.”

“Great, Sy, but how come the black? I remember that Sun-spectrum poster that Al had up in his shop once. Lotsa sharp dark lines that Cathleen said were from different elements absorbing little slices of that rainbow background. But there were plenty of colors left over to make white.”

“Impressive memory, Vinnie. That was what, three years ago? Anyhow, those absorption lines come from separated atoms floating in the hot gas of the solar atmosphere. Quantum mechanics says that an isolated atom has a characteristic set of electron configurations, each with its own energy level. Say an incoming photon meets a gas atom. If the photon’s energy just matches the difference between the atom’s current configuration and some other configuration, suddenly the atom’s in the new configuration and no more photon. It has to match just right or no absorption. Those sharp lines come from that selectivity, OK?”

“So how do you get total black from selective atoms?”

“You don’t. You get black from less‑selective molecules and larger structures. Atoms right next to each other bring entanglement into the action — which electron is where on which atom? Many more configurations, many more differences between energy level pairs, many more lines that can overlap to make broad absorption bands. Suppose you’ve got some glass or plastic doped to have a single band sucking up everything between orange and green. Shine white light into it. Only red light and blue light come through. We see that as purple, a color that’s not even in the spectrum. Make that band even broader like it is with metals and rocks and iron sulfide; nothing gets through.”

“Then how do they do those glasses that get dark or light depending? The factory can’t put chemicals in but take ’em out temporary‑like when you walk inside.”

“Good point. In fact, the glass composition stays the same, sort of. The factory puts in chemicals that change their structure depending on the light level. If you dope optical glass with silver chloride crystallites, for instance, UV light can energize a chloride’s electron up to where it can leave the chloride and be captured by a silver ion. Do that with enough silver ions in the crystallite and you have a tiny piece of silver metal. Enough pieces and the glass looks gray, at least until heat energy joggles things back to the silver chloride ground state. For plastic lenses they use a subtler strategy — large‑ish molecules with spread‑out electron structures. UV light energizes an electron to another level and the molecule twitches to an opaque alternate form that relaxes when heat shakes it down.”

“Heat, huh? No wonder mine don’t work so good on the beach.”

~~ Rich Olcott

Galaxies Fluffy And Faint

On By rolcottIn Astronomy: Stellar Science, Cosmology, UncategorizedLeave a comment

Cathleen’s at the coffee shop’s baked goods counter. “A lemon scone, please, Al.”

I’m next in line. “Lemon sounds good to me, too. It’s a warm day.”

The Pinwheel Galaxy, NGC 5457
Credit: ESA/Hubble

“Sure thing, Sy. Hey, got a question for you, Cathleen, you bein’ an Astronomer and all. I just saw an Astronomy news item about a fluffy galaxy and they mentioned a faint galaxy. Are they the same and why the excitement?”

“Not the same, Al. It’ll be easier to show you in pictures. Sy, may I borrow Old Reliable?”

“Sure, here.”

“Thanks. OK, Al, here’s a classic ‘grand design‘ spiral galaxy, NGC 5457, also known as The Pinwheel. Gorgeous, isn’t it?”

“Sure is. Hey, I’ve wondered — what does ‘NGC‘ stand for, National Galaxy Collection or something?”

“Nope. The ‘G‘ doesn’t even stand for ‘Galaxy‘. It’s ‘New General Catalog‘. Anyway, here’s NGC 2775, one of our prettiest fluffies. Doesn’t look much like the Pinwheel or Andromeda, does it?”

NGC 2775
Credit: NASA / ESA / Hubble / J. Lee / PHANGS-HST Team / Judy Schmidt

“Nah, those guys got nice spiral arms that sort of grow out of the center. This one looks like there’s an inside edge to all the complicated stuff. And it’s got what, a hundred baby arms.”

“The blue dots in those ‘baby arms’ are young blue stars. They’re separated by dark lanes of dust just like the dark lanes in classic spirals. The difference is that these lanes are much closer together. The grand design spirals are popular photography subjects in your astronomy magazines, Al, but they’re only about 10% of all spirals. I’ll bet your news item was about 2775 because we’re just coming to see how mysterious this one is.”

“What’s mysterious about it?”

“That central region. It’s huge and smooth, barely any visible dust lanes and no blue dots. It’s bright in the infra‑red, which is what you’d expect from a population of old red stars. In the ultra‑violet, though, it’s practically empty — just a small dot at the center. UV is high‑energy light. It generally comes from a young star or a recent nova or a black hole’s accretion disk. The dot is probably a super-massive back hole. but its image is just a tiny fraction of the smooth region’s width. With a billion red stars in the way it’s hard to see how the black hole’s gravity field could have cleaned up all the dust that should be in there. Li’l Fluffy here is just begging for some Astrophysics PhD candidates to burn computer time trying to explain it.”

NGC 1052-DF2
Credit: NASA, ESA, and P. van Dokkum (Yale University)

“What about Li’l Faint?”

“That’s probably this one, NGC 1052-DF2. Looks a bit different, doesn’t it?

“I’ll say. It’s practically transparent. Is it a thing at all or just a smudge on the lens?”

“Not a smudge. We’ve got multiple images in different wavelength ranges from multiple observatories, and there’s another similar object, NGC 1052-DF4, in the same galaxy group. We even have measurements from individual stars and clusters in there. The discovery paper claimed that DF2 is so spread out because it lacks the dark matter whose gravity compacts most galaxies. That led to controversy, of course.”

“Is there anything in Science that doesn’t? What’s this argument?”

“It hinges on distance, Sy. The object is about as wide as the Milky Way but we see only 1% as many stars. Does their mass exert enough gravitational force to hold the structure together? There’s a fairly good relationship between a galaxy’s mass and its intrinsic brightness — more stars means more emitting surface and more mass. We know how quickly apparent brightness drops with distance. From other data the authors estimated DF2 is 65 lightyears away and from its apparent brightness they back‑calculated its mass to be just about what you’d expect from its stars alone. No dark matter required to prevent fly‑aways. Another group using a different technique estimated 42 lightyears. That suggested a correspondingly smaller luminous mass and therefore a significant amount of dark matter in the picture. Sort of. They’re still arguing.”

“But why does it exist at all?”

“That’s another question.”

~~ Rich Olcott

  • Thanks to Oriole for suggesting this topic.

An Italianate Mantle Piece

On By rolcottIn Astronomy: Planetary Science, UncategorizedLeave a comment

Eddie has set out some tables in the Acme Building’s atrium in front of his pizza place. Mid‑morning as I walk by he’s sitting at one of them, reading a newspaper. “Morning, Eddie. Ready for walk‑in customers now that things are opening up?”

“I sure hope so, Sy. The building’s still half‑empty ’cause of the work‑from‑homers but I got hopes thanks to folks like you comin’ in.”

“I’ll drop down for lunch later. Don’t see many actual print newspapers these days. What’s in there?”

“Oh, this is the weekly from my cousin in Catania. Etna’s acting up again, as usual.”

“Catania?”

“City on the southeast coast of Sicily, about 20 miles away from the volcano. Even with the earthquakes and eruptions Catania’s almost 3000 years old. Funny, in Italy we got Etna and Vesuvius and Stromboli, Greece has Santorini and Methana, there’s a whole bunch strung out through Turkey — wonder why they all line up like that.”

A new voice behind me, but somehow familiar. “Tectonics.”

I turn. It’s the fellow with the dinosaur theory. “Hello, there. I thought you were a paleontologist.”

“Nah, I prefer really old rocks. The Paleontology course was part of my Geology program. You’re Cathleen’s friend Sy, aren’t you?”

“Guilty as charged. If I recall correctly, you’re Kareem who won the Ceremonial Broom?”

“Guilty as charged.”

“Will you guys quit playing games and just answer the question? What’s with those volcanoes?”

“Sorry, Eddie. You know about continental drift, right, that the continents are big slabs that float on top of the Earth’s molten‑metal insides?”

“Sort of, Kareem. Which brings up another question. If the layer underneath is molten metal, how come the volcanoes spit rock instead of metal? Anyway, how do we know it’s not rock all the way down?”

“Go easy on the guy, Eddie, you’re up to three questions already. Let him catch a breath.”

“Thanks, Sy. Last one first — we get a planet’s density from its size and orbit. For Earth it’s about 5.5 megagrams per cubic meter. For comparison, silicate rocks at the surface cluster around 2.7 and iron runs 7.9. Earth is just too heavy to be rock all the way down.”

“Those numbers put Earth almost exactly half-way between rock and iron. That tells me that half the planet’s mass is rocky. Surely the crust isn’t really that thick.”

“You might be surprised, Sy. Remember, volume goes up as the cube of the radius so it doesn’t take much crust thickness to make a large volume. Mind if I use a paper napkin, Eddie?”

“Nah, go ahead.”

“OK, here’s a really simplistic model. Suppose there’s just two layers, core and silicates, and density within each is uniform which means that mass is strictly proportional to volume times density. Let’s guess that core density is twice silicate density. If the core mass is half the planet’s mass, the core radius comes to … 69% of the total and the silicate layer is 1900 kilometers thick. That’s 2/3 of the way down to the bottom of the mantle, Earth’s real middle layer between crust and core. Almost embarrassingly good agreement, considering. Anyway, Eddie, it can’t be rock all the way down and the metallic component is pretty well trapped below megameters of rock. What escapes is the heat that melts the rocks for volcanoes to spit.”

“You started out with metal in the middle of the Earth and then you switched to iron. Which is it and how do you know?”

“It is metallic, mostly iron and nickel. We’ve got four lines of evidence for that. Meteorites are the oldest. Lots of them are stony, but about 6% are a combination of two nickel‑iron alloys. We think those came to us from planetoids that weren’t harvested when the planets were under construction. Second is Earth’s magnetic field, which we think is generated by currents of molten metal deep within the planet. Third is seismic data combined with lab data on how waves travel through different materials at high temperature and pressure. The observed combination’s consistent with a nickel‑iron core. Fourth comes from nuclear theory and astrophysical observation — iron’s by far the most common metallic element in the Universe. Build with what you got.”

“But what about the volcanoes?”

~~ Rich Olcott

Here’s a Different Angle

On By rolcottIn Astronomy: Planetary Science, Physics: Fundamentals, UncategorizedLeave a comment

“OK, Sy, so there’s a bulge on the Moon’s side of the Earth and the Earth rotates but the bulge doesn’t and that makes the Moon’s orbit just a little bigger and you’ve figured out that the energy it took to lift the Moon raised Earth’s temperature by a gazillionth of a degree, I got all that, but you still haven’t told Al and me how the lifting works.”

“You wouldn’t accept it if I just said, ‘The Moon lifts itself by its bootstraps,’ would you?”

“Not for a minute.”

“And you don’t like equations. <sigh> OK, Al, pass over some of those paper napkins.”

“Aw geez, Sy.”

“You guys asked the question and this’ll take diagrams, Al. Ante up. … Thanks. OK, remember the time Cathleen and I caught Vinnie here at Al’s shop playing with a top?”

“Yeah, and he was spraying paper wads all over the place.”

“I wasn’t either, Al, it was the top sending them out with centri–…, some force I can never remember whether it’s centrifugal or centripetal.”

“Centrifugal, Vinnie, –fugal– like fugitive, outward‑escaping force. It’s one of those ‘depends on how you look at it‘ fictitious forces. From where you were sitting, the wads looked like they were flying outward perpendicular to the top’s circle. From a wad’s point of view, it flew in a straight line tangent to the circle. It’s like we have two languages, Room and Rotor. They describe the same phenomena but from different perspectives.”

“Hey, it’s frames again, ain’t it?”

“Newton’s inertial frames? Sort‑of but not quite. Newton’s First Law only holds in the Room frame — no acceleration, motion is measured by distance, objects at rest stay put. Any other object moves in a straight line unless its momentum is changed by a force. You can tackle a problem by considering momentum and force components along separate X and Y axes. Both X and Y components work the same way — push twice as hard in either direction, get twice the acceleration in that direction. Nice rules that the Rotor frame doesn’t play by.”

“I guess not. The middle’s the only place an object can stay put, right?”

“Exactly, Al. Everything else looks like it’s affected by weird, constantly‑varying forces that’re hard to describe in X‑Y terms.”

“So that breaks Newton’s physics?”

“Of course not. We just have to adapt his F=m·a equation (sorry, Vinnie!) to Rotor conditions. For small movements we wind up with two equations. In the strict radial direction it’s still F=m·a where m is mass like we know it, a is acceleration outward or inward, and F is centrifugal or centripetal, depending. Easy. Perpendicular to ‘radial‘ we’ve got ‘angular.’ Things look different there because in that direction motion’s measured by angle but Newton’s Laws are all about distances — speed is distance per time, acceleration is speed change per time and so forth.”

“So what do you do?”

“Use arc length. Distance along an arc is proportional to the angle, and it’s also proportional to the radius of the arc, so just multiply them together.”

“What, like a 45° bend around a 2-foot radius takes 90 feet? That’s just wrong!”

“No question, Al. You have to measure the angle in the right units. Remember the formula for a circle’s circumference?”

“Sure, it’s 2πr.”

“Which tells you that a full turn’s length is 2π times the radius. We can bridge from angle to arc length using rotational units so that a full turn, 360°, is 2π units. We’ll call that unit a radian. Half a circle is π radians. Your 45° angle in radians is π/4 or about ¾ of a radian. You’d need about (¾)×(2) or 1½ feet of whatever to get 45° along that 2-foot arc. Make sense?”

“Gimme a sec … OK, I’m with you.”

“Great. So if angular distance is radius times angle, then angular momentum which is mass times distance per time becomes mass times radius times angle per time.”

“”Hold on, Sy … so if I double the mass I double the momentum just like always, but if something’s spinning I could also double the angular momentum by doubling the radius or spinning it twice as fast?”

“Couldn’t have put it better myself, Vinnie.”

~~ Rich Olcott

Question Time

On By rolcottIn Astronomy: Planetary Science, Cosmology, Crazy Theories, UncategorizedLeave a comment

Cathleen unmutes her mic. “Before we wrap up this online Crazy Theories contest with voting for the virtual Ceremonial Broom, I’ve got a few questions here in the chat box. The first question is for Kareem. ‘How about negative evidence for a pre-mammal civilization? Played-out mines, things like that.‘ Kareem, over to you.”

“Thanks. Good question but you’re thinking way too short a time period. Sixty‑six million years is plenty of time to erode the mountain a mine was burrowing into and take the mining apparatus with it.

“Here’s a different kind of negative evidence I did consider. We’re extracting coal now that had been laid down in the Carboniferous Era 300 million years ago. At first, I thought I’d proved no dinosaurs were smart enough to dig up coal because it’s still around where we can mine it. But on second thought I realized that sixty-six million years is enough time for geological upthrust and folding to expose coal seams that would have been too deeply buried for mining dinosaurs to get at. So like the Silurian Hypothesis authors said, no conclusions can be drawn.”

“Nice response, Kareem. Jim, this one’s for you. ‘You said our observable universe is 93 billion lightyears across, but I’ve heard over and over that the Universe is 14 billion years old. Did our observable universe expand faster than the speed of light?‘”

“That’s a deep space question, pun intended. The answer goes to what we mean when we say that the Hubble Flow expands the Universe. Like good Newtonian physicists, we’re used to thinking of space as an enormous sheet of graph paper. We visualize statements like, ‘distant galaxies are fleeing away from us‘ as us sitting at one spot on the graph paper and those other galaxies moving like fireworks across an unchanging grid.

“But that’s not the proper post-Einstein way to look at the situation. What’s going on is that we’re at our spot on the graph paper and each distant galaxy is at its spot, but the Hubble Flow stretches the graph paper. Suppose some star at the edge of our observable universe sent out a photon 13.7 billion years ago. That photon has been headed towards us at a steady 300000 kilometers per second ever since and it finally reached an Earth telescope last night. But in the meantime, the graph paper stretched underneath the photon until space between us and its home galaxy widened by a factor of 3.4.

“By the way, it’s a factor of 3.4 instead of 6.8 because the 93 billion lightyear distance is the diameter of our observable universe sphere, and the photon’s 13.7 billion lightyear trip is that sphere’s radius.

“Mmm, one more point — The Hubble Flow rate depends on distance and it’s really slow on the human‑life timescale. The current value of the Hubble Constant says that a point that’s 3×1019 kilometers away from us is receding at about 70 kilometers per second. To put that in perspective, Hubble Flow is stretching the Moon away from us by 3000 atom‑widths per year, or about 1/1300 the rate at which the Moon is receding because of tidal friction.”

“Nice calculation, Jim. Our final question is for Amanda. ‘Could I get to one of the other quantum tracks if I dove into a black hole and went through the singularity?‘”

“I wouldn’t want to try that but let’s think about it. Near the structure’s center gravitational intensity compresses mass-energy beyond the point that the words ‘particle’ and ‘quantum’ have meaning. All you’ve got is fields fluctuating wildly in every direction of spacetime. No sign posts, no way to navigate, you wouldn’t be able to choose an exit quantum track. But you wouldn’t be able to exit anyway because in that region the arrow of time points inward. Not a sci‑fi story with a happy ending.”

“<whew> Alright, folks, time to vote. Who presented the craziest theory? All those in favor of Kareem, click on your ‘hand’ icon. … OK. Now those voting for Jim? … OK. Now those voting for Amanda? … How ’bout that, it’s a tie. I guess for each of you there’s a parallel universe where you won the virtual Ceremonial Broom. Congratulations to all and thanks for such an interesting evening. Good night, everyone.”

~~ Rich Olcott

Too Many Schrödingers

On By rolcottIn Cosmology, Crazy Theories, Physics: Quantum Mechanics, UncategorizedLeave a comment

Cathleen takes back control of the conference software. “Thanks, Jim. OK, the final contestant in our online Crazy Theories contest is the winner of our last face-to-face event where she told us why Spock and horseshoe crabs both have green blood. You’re up, Amanda.”

“Thanks, and hello out there. I can’t believe Jim and I are both talking about parallel universes. It’s almost like we’re thinking in parallel, right?”

<Jim’s mic is muted so he makes gagging motions>

“We need some prep work before I can talk about the Multiverse. I’m gonna start with this heat map of North America at a particular time. Hot in the Texas panhandle, cool in British Columbia, no surprise. You can do a lot with a heat map — pick a latitude and longitude, it tells you the relative temperature. Do some arithmetic on the all numbers and you can get average temperature, highs and lows, front strength in degrees per mile, lots of stuff like that.

“You build this kind of map by doing a lot of individual measurements. If you’re lucky you can summarize those measurements with a function, a compact mathematical expression that does the same job — pick a latitude and longitude, it tells you the value. Three nice things about functions — they take up a lot less space than a map, you can use straightforward mathematical operations on them so getting statistics is less work than with a map, and you can form superpositions by adding functions together.”

Cathleen interrupts. “Amanda, there’s a question in the chat box. ‘Can you give an example of superposition?’“

“Sure. You can superpose simple sine‑wave functions to describe chords for sound waves or blended colors for light waves, for instance.

“Now when we get to really small‑scale thingies, we need quantum calculations. The question is, what do quantum calculations tell us? That’s been argued about for a hundred years because the values they generate are iffy superpositions. Twenty percent of this, eighty percent of that. Everybody’s heard of that poor cat in Schrödinger’s box.

“Many researchers say the quantum values are relative probabilities for observing different results in an experiment — but most of them carefully avoid worrying about why the answers aren’t always the same. Einstein wanted to know what Bohr was averaging over to get his averages. Bohr said it doesn’t matter, the percentages are the only things we can know about the system and it’s useless to speculate further.

“Hugh Everett thought bigger. He suggested that the correct quantum function for an observation should include experiment and experimenter. He took that a step further by showing that a proper quantum function would need to include anyone watching the experimenter and so on. In fact, he proposed, maybe there’s just one quantum function for the entire Universe. That would have some interesting implications.

“Remember Schrödinger’s catbox with two possible experimental results? Everett would say that his universal quantum function contains a superposition of two component sub-functions — happy Schrödinger with a live kitty and sad Schrödinger with a disposal problem. Each Schrödinger would be quite certain that he’d seen the definite result of a purely random operation. Two Schrödingers in parallel universes going forward.

“But in fact there’d be way more than two. When Schrödinger’s eye absorbs a photon, or maybe doesn’t, that generates another pair of universes. So do the quantum events that occur as his nerve cells fire, or don’t. Each Schrödinger moves into the future embedded in a dense bundle of parallel universes.”

Cathleen interrupts. “Another question. ‘What about conservation of mass?‘”

“Good question, whoever asked that. Everett doesn’t address that explicitly in his thesis, but I think he assumed the usual superposition math. That always includes a fix‑up step so that the sum of all the pieces adds up to unity. Half a Schrödinger mass on one track and half on the other. Even as each of them splits again and again and again the total is still only one Schrödinger‑mass. There’s other interpretation — each Schrödinger’s universe would be independent of the others so there’s no summing‑up to generate a conservation‑of‑mass problem. Your choice.

“Everett traded quantum weirdness for a weird Universe. Not much of a trade-off, I think.”

~~ Rich Olcott

Worlds Enough And Time Reversed

On By rolcottIn Cosmology, Crazy Theories, UncategorizedLeave a comment

Cathleen unmutes her mic. “Thanks, Kareem. Our next Crazy Theory presentation is from one of my Cosmology students, Jim.”

“Thanks, Cathleen. Y’all have probably heard about how Relativity Theory and Quantum Mechanics don’t play well together. Unfortunately, people have mixed the two of them together with Cosmology to spawn lots of Crazy Theories about parallel universes. I’m going to give you a quick look at a couple of them. Fasten your seat belt, you’ll need it.

“The first theory depends on the idea that the Universe is infinitely large and we can only see part of it. Everything we can see — stars, galaxies, the Cosmic Microwave Background — they all live in this sphere that’s 93 billion lightyears across. We call it our Observable Universe. Are there stars and galaxies beyond the sphere? Almost certainly, but their light hasn’t been in flight long enough to reach us. By the same token, light from the Milky Way hasn’t traveled far enough to reach anyone outside our sphere.

“Now suppose there’s an alien astronomer circling a star that’s 93 billion lightyears away from us. It’s in the middle of its observable universe just like we’re in the middle of ours. And maybe there’s another observable universe 93 billion lightyears beyond that, and so on to infinity. Oh, by the way, it’s the same in every direction so there could be an infinite number of locally-observable universes. They’re all in the same space, the same laws of physics rule everywhere, it’s just that they’re too far apart to see each other.

“The next step is a leap. With an infinite number of observable universes all following the same physical laws, probability says that each observable universe has to have twins virtually identical to it except for location. There could be many other people exactly like you, out there billions of lightyears away in various directions, sitting in front of their screens or jogging or whatever. Anything you might do, somewhere out there there’s at least one of you doing that. Or maybe a mirror image of you. Lots of yous in lots of parallel observable universes.”

“I don’t like that theory, on two grounds. First, there’s no way to test it so it’s not science. Second, I think it plays fast and loose with the notion of infinity. There’s a big difference between ‘the Universe is large beyond anything we can measure‘ and ‘the Universe is infinite‘. If you’ve been reading Sy Moire’s stuff you’ve probably seen his axiom that if your theory contains an infinity, you’ve left out physics that would stop that. Right, Cathleen?”

Cathleen unmutes her mic. “That quote’s good, Jim.”

“Thanks, so’s the axiom. So that’s one parallel universe theory. OK, here’s another one and it doesn’t depend on infinities. The pop‑science press blared excitement about time‑reversal evidence from the ANITA experiment in Antarctica. Unfortunately, the evidence isn’t anywhere as exciting as the reporting has been.

“The story starts with neutrinos, those nearly massless particles that are emitted during many sub‑atomic reactions. ANITA is one kind of neutrino detector. It’s an array of radio receivers dangling from a helium‑filled balloon 23 miles up. The receivers are designed to pick up the radio waves created when a high‑energy neutrino interacts with glacier ice, which doesn’t happen often. Most of the neutrinos come in from outer space and tell us about solar and stellar activity. However, ANITA detected two events, so‑called ‘anomalies,’ that the scientists can’t yet explain and that’s where things went nuts.

“Almost as soon as the ANITA team sent out word of the anomalies, over three dozen papers were published with hypotheses to account for them. One paper said maybe the anomalies could be interpreted as a clue to one of Cosmology’s long‑standing questions — why aren’t there as many antiprotons as protons? A whole gang of hypotheses suggest ways that maybe something in the Big Bang directed protons into our Universe and antiprotons into a mirror universe just like ours except charges and spacetime are inverted with time running backwards. There’s a tall stack of maybes in there but the New York Post and its pop‑sci allies went straight for the Bizarro parallel universe conclusion. Me, I’m waiting for more data.”

~~ Rich Olcott

Smart Dinosaurs?

On By rolcottIn Astronomy: Planetary Science, Crazy Theories, UncategorizedLeave a comment

<chirp, chirp> “Moire here, what can I do for you while staying six feet away?”

“Hi, Sy, this is Cathleen. you’re invited to to an experiment.”

“What sort of experiment?”

“You’ve been to a few of our ‘Crazy Theory’ events. We can’t do those now, of course, but we’re trying it online. Interested?”

“Sounds like fun. Email me the details and I’ll dial in.”

“Hi, everyone, welcome to our first-ever online ‘Crazy Theories’ seminar. I’m afraid it’ll be a bit different from our traditional affairs. Everyone but the presenter’s on mute so don’t bother shouting encouragement or booing. Any spitballs or wadded-up paper napkins you throw you get to clean up. As always at the end we’ll take a vote to award the Ceremonial Broom for the craziest theory. Type your questions and comments in the chat box; we’ll get to them after the presenter finishes. Everybody got all that? OK, our first presenter is from my Planetology class. Go ahead, Kareem.”

“Hey, everybody. I’m Kareem and my Crazy Theory isn’t mine, personally, but it’s the one that got me into Planetology class. Its was in this science fiction novel I read a couple of years ago. The story’s complicated and has a lot of science that I didn’t understand, but the part that caught my imagination was his idea that what killed off the dinosaurs was smart dinosaurs.”

<consults notes>

“A little history first. In the late 1970s two scientists named Alvarez discovered that all around the Earth there’s a thin layer of soil with more than ten times the normal amount of an element called iridium. They found that the layer was 66 million years old, which just matched the end of the Cretaceous Era when the last of the dinosaurs died off. They knew that some meteorites have a lot of iridium so in 1980 they suggested that a meteor strike must have done the deed.

“That idea was so controversial that John McLoughlin came up with his own explanation and based his book on it. He supposed that about 66 million years ago evolution produced intelligent dinosaurs that took over the planet the way that we humans have in our time. They weren’t huge like T‑rex but they were big enough to use Triceratops as draft and meat animals and smart enough to develop lots of iridium‑based technology like we use copper. Anyway, they got into a world war and that was what wiped everything out and left behind the traces of iridium.”

<gulps down soda>

“McLaughlin’s book came out in 1988. Since than we’ve learned that the Alvarez guys were basically right although there was some other stuff going on, too. But the book got me thinking that maybe there could have been a world‑wide civilization and the only things left after 66 million years were bones and this trace of a metal they used. Humans have only been around for like a hundred thousand years and we’ve only been doing metals big‑time for a few hundred which is teeny compared to a million years. A paleontologist wouldn’t even be able to detect a time period that small. So my Crazy Theory is, maybe there were smart dinosaurs or something and we just haven’t found evidence for them.”

<burp>

“Ever since then I’ve kept an eye out for publications about what a vanished civilization might leave behind for us to discover. In this book Weisman lays out survival times for our civilization’s stuff — plastic, houses, roads and so on. Pretty much everything but Mount Rushmore and the Chunnel will have dissolved or eroded away much sooner than a million years. Really readable if you want more details.”

<more soda>

“I also found a paper, ‘The Silurian Hypothesis,’ that took a more technical approach. Their big library research project pulled results from scores of geologic isotope analysis and fossil survey reports looking for ancient times that resemble Earth’s sudden change since the start of the Industrial Age — climate, species declines, whatever. They found about a dozen, but as they said, ‘the known unique markers might not be indicative, while the (perhaps) more expected markers are not sufficient.’ In other words, my Crazy Theory might be crazy. Or maybe not.”

~~ Rich Olcott

Presbyopic Astronomy

On By rolcottIn Astronomy: Multi-messenger, Astronomy: Techniques, Cosmology, UncategorizedLeave a comment

Her phone call done, Cathleen returns to the Spitzer Memorial Symposium microphone with her face all happiness. “Good news! Jim, the grant came through. Your computer time and telescope access are funded. Woo-hoo!!”

<applause across the audience and Jim grins and blushes>

Cathleen still owns the mic. “So I need to finish up this overview of Spitzer highlights. Where was I?”

Maybe-an-Art-major tries to help. “The middle ground of our Universe.”

“Ah yes, thanks. So we’ve looked at close-by stars but Spitzer showed us a few more surprises lurking in the Milky Way. This, for instance — most of the image is colorized from the infra‑red, but if you look close you can see Chandra‘s X‑ray view, colorized purple to highlight young stars.”

The Cepheus-B molecular cloud
X-ray: NASA/CXC/PSU/K. Getman et al.; IRL NASA/JPL-Caltech/CfA/J. Wang et al

<hushed general “oooo” from the audience>

“Giant molecular clouds like this are scattered throughout the Milky Way, mostly in the galaxy’s spiral arms. As you see, this cloud’s not uniform, it has clumps and voids. By Earth standards the cloud is still a pretty good vacuum. The clumps are about 10-15 of our atmosphere’s density, but that’s still a million times more dense than our Solar System’s interplanetary space. The clumps appear to be where new stars are born. The photons and other particles from a newly-lit star drive the surrounding dust away. My arrow points to one star with a particularly nice example of that — see the C-shape around the star?”

The maybe-an-Art-major pipes up. “How about that one just a little below center?”

“Uh-huh. There’s so much activity in that dense region that the separate shockwaves collide to create hot spots that’ll generate even more stars in the future. The clouds are mostly held together by their own gravity. They last for tens of millions of years, so we think of them as huge roiling stellar nurseries.”

“Like my kid’s day care center but bigger.”

“Mm-mm, but let’s turn to the Milky Way’s center, home of that famous black hole with the mass of four million Suns and this remarkable structure, a double-helix of warm dust.”

False-color infra-red image of the Double-Helix Nebula
The double helix nebula.
Credit: NASA/JPL-Caltech/M. Morris (UCLA)

Vinnie blurts out, “That’s a jet from a black hole! One of Newt’s babies.”

Newt can’t resist breaking into Cathleen’s pitch. “Maybe it’s a jet, Vinnie. Yes, it’s above the central galactic plane and perpendicular to it, but the helix doesn’t quite point to the central black hole.”

“So take another picture that follows it down.”

“We’d love to, but we can’t. Yet. That image came from a long-wavelength instrument that only operated during Spitzer‘s initial 5-year cold period. Believe me, there are bunches of astronomers who can’t wait for the James Webb Space Telescope‘s far-IR instruments to get into position and start doing science. Meanwhile, we’ve got just the one image and a few earlier ones from an even less-capable spacecraft. This thing may be a lit-up part of a longer structure that twists down to the black hole or at least its accretion disk. We just don’t know.”

Cathleen takes control again. “The next image comes from outside our galaxy — far outside.”

Spitzer visualization of Galaxy MACS 1149-JD1
Credit: NASA/ESA/STScI/W. Zheng (JHU), and the CLASH team

The maybe-an-Art-major snorts, “Pointillism derivative!”

“No, it’s pixels from a starfield image with a very low signal-to-noise ratio. That red blotch in the center is one of the most distant objects ever observed, gracefully named MACS 1149-JD1. It’s a galaxy 13.2 billion lightyears away. That’s so far away that the expansion of the Universe has stretched the galaxy’s emitted photons by a factor of 10.2. Spectrum-wise, 1149-JD1’s ultra-violet light skipped right past the visible range and down into the near infra-red. Intensity-wise, that galaxy’s about 5200 times further away than the Andromeda galaxy. Assuming the two are about the same overall brightness, 1149-JD1 would be about 27 million times fainter than Andromeda.”

“How can we even see anything that dim?”

“We couldn’t, except for a fortunate coincidence. Right in line between us and 1149-JD1 there’s a massive galaxy cluster whose gravity acts like a lens to focus 1149-JD1’s light.”

The seminar’s final words, from maybe-an-Art-major — “A distant light, indeed.”

~~ Rich Olcott

Myopic Astronomy

On By rolcottIn Astronomy: Planetary Science, UncategorizedLeave a comment

Cathleen goes into full-on professor mode. “OK folks, settle down for the final portion of “IR, Spitzer and The Universe,” our memorial symposium for the Spitzer Space Telescope which NASA retired on January 30. Jim’s brought us up to speed about what infra-red is and how we work with it. Newt’s given us background on the Spitzer and its fellow Great Observatories. Now it’s my turn to show some of what Astronomy has learned from Spitzer. Thousands of papers have been published from Spitzer data so I’ll just skim a few highlights, from the Solar System, the Milky Way, and the cosmological distance.”

“Ah, Chinese landscape perspective,” murmurs the maybe-an-Art-major.

“Care to expand on that?” Cathleen’s a seasoned teacher, knows how to maintain audience engagement by accepting interruptions and then using them to further her her own presentation.

“You show detail views of the foreground, the middle distance and the far distance, maybe with clouds or something separating them to emphasize the in‑between gaps.”

“Yes, that’s my plan. Astronomically, the foreground would be the asteroids that come closer to the Earth than the Moon does. Typically they reflect about as much light as charcoal so our visible-light telescopes mostly can’t find them. But even though asteroids are as cold as interplanetary space that’s still above absolute zero. The objects glow with infra-red light that Spitzer was designed to see. It found hundreds of Near-Earth Objects as small as 6 meters across. That data helped spark disaster movies and even official conversations about defending us from asteroid collisions.”

<A clique in the back of the room> “Hoo-ahh, Space Force!“

Some interruptions she doesn’t accept. “Pipe down back there! Right, so further out in the Solar System, Spitzer‘s ability to detect glowing dust was key to discovering a weird new ring around Saturn. Thanks to centuries of visible‑range telescope work, everyone knows the picture of Saturn and its ring system. The rings together form an annulus, an extremely thin circular disk with a big round hole in the middle. The annulus is bright because it’s mostly made of ice particles. The annulus rotates to match Saturn’s spin. The planet’s rotational axis and the annulus are both tilted by about 27° relative to Saturn’s orbit. None of that applies to what Spitzer found.”

Vinnie’s voice rings out. “It’s made of dust instead of ice, right ?”

Cathleen recognizes that voice. “Good shot, Vinnie, but the differences don’t stop there. The dust ring is less a disk than a doughnut, about 200 thousand times thicker than the icy rings and about 125 times wider than the outermost ice ring. But the weirdest part is that the doughnut rotates opposite to the planet and it’s in Saturn’s orbital plane, not tilted to it. It’s like the formation’s only accidentally related to Saturn. In fact, we believe that the doughnut and its companion moon Phoebe came late to Saturn from somewhere else.”

She takes a moment for a sip of coffee. “Now for the middle distance, which for our purpose is the stars of the Milky Way. Spitzer snared a few headliners out there, like TRAPPIST-1, that star with seven planets going around it. Visible-range brightness monitoring suggested there was a solar system there but Spitzer actually detected light from individual planets. Then there’s Tabby’s Star with its weird dimming patterns. Spitzer tracked the star’s infra‑red radiance while NASA’s Swift Observatory tracked the star’s emissions in the ultra‑violet range. The dimming percentages didn’t match, which ruled out darkening due to something opaque like an alien construction project. Thanks to Spitzer we’re pretty sure the variation’s just patchy dust clouds.”

Spitzer view of the Trifid Nebula
Credit: NASA/JPL-Caltech/J. Rho (SSC/Caltech)

<from the crowd in general> “Awww.”

“I know, right? Anyway, Spitzer‘s real specialty is inspecting warm dust, so no surprise, it found lots of baby stars embedded in their dusty matrix. Here’s an example. This image contains 30 massive stars and about 120 smaller ones. Each one has grown by eating the dust in its immediate vicinity and having lit up it’s now blowing a bubble in the adjacent dust.” <suddenly her cellphone rings> “Oh, sorry, this is a call I’ve got to take. Talk among yourselves, I’ll be right back.”

~~ Rich Olcott