Category: Uncategorized

SPLASH Splish plink

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

<chirp, chirp, chirp, chirp> “Moire here. This’d better be good.”

“Hello, Mr Moire. I’m one of your readers.”

“Do you have any idea what time it is?”

“Afraid not, I don’t know what time zone you’re in.”

“It’s three o’clock in the morning! Why are you calling me at this hour?”

“Oh, sorry, it’s mid-afternoon here. Modern communications tech is such a marvel. No matter, you’re awake so here’s my question. I’ve been pondering that micro black hole you’ve featured in the last couple of posts. You convinced me it would have a hard time hitting Earth but then I started thinking about it hitting the Sun. The Sun’s diameter is 100 times Earth’s so it presents 10,000 times more target area, yes? Further, the Sun’s 300,000 times more massive than Earth so it has that much more gravity. Surely the Sun is a more effective black hole attractor than Earth is.”

“That’s a statement, not a question. Worse yet, you’re comparing negligible to extremely negligible and neither one is worth losing sleep over which is what I’m doing now.”

“Wait on, I’ve not gotten to my question yet which is, suppose a black hole did happen to collide with the Sun. What would happen then?”

<yawn> “Depends on the size of the black hole. If it’s supermassive, up in the billion‑sun range, it wouldn’t hit the Sun. Instead, the Sun would hit the black hole but there’d be no collision. The Sun would just sink quietly through the Event Horizon.”

“Wouldn’t it rip apart?”

“You’re thinking of those artistic paintings showing great blobs of material being torn away by a black hole’s gravity. Doesn’t work that way, at least not at this size range.” <grabbing Old Reliable from my nightstand and key‑tapping> “Gravitational forces are distance‑dependent. Supermassives are large even by astronomical standards. The M87* black hole, the first one ESA got an image of, has the mass of 6 billion Suns and an Event Horizon three times wider than Pluto’s orbit. The tidal ripping‑apart you’re looking for only happens when the mass centers of two objects approach within Roche’s limit. Suppose a Sun‑sized star flew into M87*’s Event Horizon. Their Roche limit would be 100 astronomical units inside the Event Horizon. If any ripping happened, no evidence could escape to us.”

“Another illusion punctured.”

“Don’t give up hope. The next‑smaller size category have masses near our Sun’s. The Event Horizon of a 10‑solar‑mass black hole would be only about 60 kilometers wide. The Roche Zone for an approaching Sun is a million times wider. There’s plenty of opportunity for ferocious ripping on the way in.”

“Somehow that’s a comfort, but my question was about even smaller black holes — micro‑size flyspecks such as you wrote about. What effect would one have on the Sun?”

“You’d think it’d be a simple matter of the micro‑hole, let’s call it Mikey, diving straight to the Sun’s center while gobbling Sun‑stuff in a gluttonous frenzy, getting exponentially bigger and more voracious every second until the Sun implodes. Almost none of that would happen. The Sun’s an incredibly violent place. On initial approach Mikey’d be met with powerful, rapidly moving magnetic fields. If he’s carrying any charge at all they’d give him whip‑crack rides all around the Sun’s mostly‑vacuum outer layers. He might not ever escape down to the Convection Zone.”

“He’d dive if he escaped there or he’s electrically neutral.”

“Mostly not. The Convection Zone’s 200,000-kilometer depth takes up two‑thirds of the Sun’s volume and features hyper‑hurricane winds roaring upward, downward and occasionally sideward. Mikey would be a very small boat in a very big forever storm.”

“But surely Mikey’s density would carry him through to the core.”

“Nope, the deeper you go, the smaller the influence of gravity. Newton proved that inside a massive spherical shell, the net gravitational pull on any small object is zero. At the Sun’s core it’s all pressure, no gravity.”

“Then the pressure will force‑feed mass into Mikey.”

“Not so much. Mikey has jets and and an accretion disk. Their outward radiation pressure sets an upper limit on Mikey’s gobbling speed. The Sun will nova naturally before Mikey has any effect.”

“No worries then.”

~~ Rich Olcott

Hiding Among The Hill Spheres

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

Bright Spring sunlight wakes me earlier than I’d like. I get to the office before I need to, but there’s Jeremy waiting at the door. “Morning, Jeremy. What gets you here so soon after dawn?”

“Good morning, Mr Moire. I didn’t sleep well last night, still thinking about that micro black hole. Okay, I know now that terrorists or military or corporate types couldn’t bring it near Earth, but maybe it comes by itself. What if it’s one of those asteroids with a weird orbit that intersects Earth’s orbit? Could we even see it coming? Aren’t we still in danger of all those tides and quakes and maybe it’d hollow out the Earth? How would the planetary defense people handle it?”

“For so early in the day you’re in fine form, Jeremy. Let’s take your barrage one topic at a time, starting with the bad news. We know this particular object would radiate very weakly and in the far infrared, which is already a challenge to detect. It’s only two micrometers wide. If it were to cross the Moon’s orbit, its image then would be about a nanoarcsecond across. Our astrometers are proud to resolve two white‑light images a few milliarcseconds apart using a 30‑meter telescope. Resolution in the far‑IR would be about 200 times worse. So, we couldn’t see it at a useful distance. But the bad news gets worse.”

“How could it get worse?”

“Suppose we could detect the beast. What would we do about it? Planetary defense people have proposed lots of strategies against a marauding asteroid — catch it in a big net, pilot it away with rocket engines mounted on the surface, even blast it with A‑bombs or H‑bombs. Black holes aren’t solid so none of those would work. The DART mission tried using kinetic energy, whacking an asteroid’s moonlet to divert the moonlet‑asteroid system. It worked better than anyone expected it to, but only because the moonlet was a rubble pile that broke up easily. The material it threw away acted as reaction mass for a poorly controlled rubble rocket. Black holes don’t break up.”

“You’re not making getting to sleep any easier for me.”

“Understood. Here’s the good news — the odds of us encountering anything like that are gazillions‑to‑one against. Consider the probabilities. If your beast exists I don’t think it would be an asteroid or even from the Kuiper Belt. Something as exotic as a primordial black hole or a mostly‑evaporated stellar black hole couldn’t have been part of the Solar System’s initial dust cloud, therefore it wouldn’t have been gathered into the Solar System’s ecliptic plane. It could have been part of the Oort cloud debris or maybe even flown in on a hyperbolic orbit from far, far away like ‘Oumuamua did. Its orbit could be along any of an infinite number of orientations away from Earth’s orbit. But it gets better.”

“I’ll take all the improvement you can give me.”

“Its orbital period is probably thousands of years long or never.”

“What difference does that make?”

“You’ve got to be in the right place at the right time to collide. Earth is 4.5 billion years old. Something with a 100‑year orbit would have had millions of chances to pass through a spot we happen to occupy. An outsider like ‘Oumuamua would have only one. We can even figure odds on that. It’s like a horseshoe game where close enough is good enough. The object doesn’t have to hit Earth right off, it only has to pierce our Hill Sphere.”

“Hill Sphere?”

“A Hill Sphere is a mathematical abstract like an Event Horizon. Inside a planet’s Sphere any nearby object feels a greater attraction to the planet than to its star. Velocities permitting, a collision may ensue. The Sphere’s radius depends only on the average planet–star distance and the planet and star masses. Earth’s Hill Sphere radius is 1.5 million kilometers. Visualize Hill Spheres crowded all along Earth’s orbit. If the interloper traverses any Sphere other than the one we’re in, we survive. It has 1 chance out of 471 . Multiply 471 by 100 spheres sunward and an infinity outward. We’ve got a guaranteed win.”

“I’ll sleep better tonight.”

~~ Rich Olcott

A Tug at The Ol’ Gravity Strings

On By rolcottIn Physics: Black Holes and Relativity, Space Travel, UncategorizedLeave a comment

“Why, Jeremy, you’ve got such a stunned look on your face. What happened? Is there anything I can do to help?”

“Sorry, Mr Moire. I guess I’ve been thinking too much about this science fiction story I just read. Which gelato can I scoop for you?”

“Two dips of mint, in a cup. Eddie went heavy with the garlic on my pizza this evening. What got to you in the story?”

“The central plot device. Here’s your gelato. In the story, someone locates a rogue black hole hiding in the asteroid belt. Tiny, maybe a few thousandths of a millimeter across, but awful heavy. A military‑industrial combine uses a space tug to tow it to Earth orbit for some kind of energy source, but their magnetic grapple slips and the thing falls to Earth. Except it doesn’t just fall to Earth, it’s so small it falls into Earth and now it’s orbiting inside, eating away the core until everything crumbles in. I can’t stop thinking about that.”

“Sounds pretty bad, but it might help if we run the numbers.” <drawing Old Reliable from its holster> “First thing — Everything about a black hole depends on its mass, so just how massive is this one?” <tapping on Old Reliable’s screen with gelato spoon> “For round numbers let’s say its diameter is 0.002 millimeter. The Schwartzschild ‘radius’ r is half that. Solve Schwartschild’s r=2GM/c² equation for the mass … plug in that r‑value … mass is 6.7×1020 kilograms. That’s about 1% of the Moon’s mass. Heavy indeed. How did they find this object?”

“The story didn’t say. Probably some asteroid miner stumbled on it.”

“Darn lucky stumble, something only a few microns across. Not likely to transit the Sun or block light from any stars unless you’re right on top of it. Radiation from its accretion disk? Depends on the history — there’s a lot of open space in the asteroid belt but just maybe the beast encountered enough dust to form one. Probably not, though. Wait, how about Hawking radiation?”

“Oh, right, Stephen Hawking’s quantum magic trick that lets a black hole radiate light from just outside its Event Horizon. Does Old Reliable have the formulas for that?”

“Sure. From Hawking’s work we know the object’s temperature and that gives us its blackbody spectrum, then we’ve got the Bekenstein‑Hawking equation for the power it radiates. Mind you, the spectrum will be red‑shifted to some extent because those photons have to crawl out of a gravity well, but this’ll give us a first cut.” <more tapping> “Chilly. 170 kelvins, that’s 100⁰C below room temperature. Most of its sub‑nanowatt emission will be at far infrared wavelengths. A terrible beacon. But suppose someone did find this thing. I wonder what’ll it take to move it here.”

“Can you calculate that?”

“Roughly. Suppose your space tug follows the cheapest possible flight path from somewhere near Ceres. Assuming the tug itself has negligible mass … ” <more tapping> “Whoa! That is literally an astronomical amount of delta-V. Not anything a rocket could do. Never mind. But where were they planning to put the object? What level orbit?”

“Well, it’s intended to beam power down to Earth. Ions in the Van Allen Belts would soak up a lot of the energy unless they station it below the Belts. Say 250 miles up along with the ISS.”

“Hoo boy! A thousand times closer than the Moon. Force is inverse to distance squared, remember. Wait, that’s distance to the center and Earth’s radius is about 4000 miles so the 250 miles is on top of that. 250,000 divided by 4250 … quotient squared … is a distance factor of almost 3500. Put 1% of the Moon that close to the Earth and you’ve got ocean tides 36 times stronger than lunar tides. Land does tides, too, so there’d be earthquakes. Um. The ISS is on a 90‑minute orbit so you’d have those quakes and ocean tides sixteen times a day. I wouldn’t worry about the black hole hollowing out the Earth, the tidal effect alone would do a great job of messing us up.”

“The whole project is such a bad idea that no-one would or could do it. I feel better now.”

~~ Rich Olcott

The Situation of The Gravity

On By rolcottIn General: Fun Stuff, UncategorizedLeave a comment

<bomPAH-dadadadaDEEdah> It’s been a while since Old Reliable blared that unregistered ringtone. Sure enough, the phone function’s caller‑ID display says 710‑555‑1701.  “Commander Baird, I presume? Long time no hear.”

<downcast tone with a hint of desperation> “It’s Lieutenant now.”

“Sorry to hear that. What happened?”

“Project Lonesome was a bust. It took us years to assemble those two planetoids but getting them into the right orbits around the black hole was more of a challenge than we planned for. Planetoid Pine got away from us and fell down through the Event Horizon. One big blast of inforon radiation and no more project. We lost a few robot space tugs but all carbon‑based personnel survived. Medical Bay just now pronounced me healthy — it’s amazing what they can do about pervasive sub‑cellular damage these days. The Board of Inquiry decided no‑one was at fault but they down‑ranked me because I was primary advocate for a jinxed project.”

“Well, those 15-minute orbits were a gamble all along. So why this phone call?”

“You know how it is, sitting in Med Bay with nothing much to do. I was poking around and happened to read a few of the files you’re working on—”

“Which ones?”

“The Projects directory.”

“But those are client files I’ve encrypted with the latest technology.”

“Oh, please, Mr Moire, I am calling from the 24th Century. Upton’s algorithm for zeta‑function decryption is ancient history. Don’t worry, your client’s secrets are safe, although one of your clients may not be.”

“Whoa, say what? Which one? What kind of danger? They all seem healthy, look both ways before crossing the street, that sort of thing.”

“One of those projects is extremely dangerous.”

“Which one? The biometrically‑lockable archery bow shouldn’t cause any problems. The electric yoga outfit? I triple‑checked the wiring and insulation specs, they’re safe and reliable. The robot rabbit? Surely not. Does this involve lethal spy‑craft of some sort? I try to avoid military work.”

“No, it’s the perpetual motion machine.”

“Ralphie’s project? Laws of Thermodynamics and all, I told him that’s just not going to work. He insisted I check his blueprints to make sure nothing’s going to blow up. I gave them a quick glance, didn’t see anything dicey.”

“It wouldn’t be obvious, especially not in view of your primitive science—”

“Hey!”

“No offense intended, Mr Moire, but it is primitive from my perspective. Two hundred years make a difference. Consider the state of Earth’s science in 1723 — Graham was still perfecting the pendulum clock.”

“Point taken, reluctantly. So what should I look for, and why?”

“The Prime Directive applies across time periods, too, so I can’t go into detail with you. I’ll just say it’s not any one component, it’s the overall physical arrangement and what will happen when he powers up. Move the boxy bits closer together or further apart by two centimeters and the danger’s gone.”

“But what’s the danger? I can’t just tell him to reconfigure for no reason.”

“Directed gravity, Mr Moire, the sculpting of spacetime. It’s the reason we don’t need safety belts on a starship — we manufacture local gravity that always pulls toward the deck. In fact, directed gravity’s at the heart of warp drive technology. Cochrane stumbled on the effect accidentally but fortunately his lab was in a reinforced hard‑rock tunnel so damage was limited.”

“Anti-gravity? Oh, that’d be so cool. Flying cars at last, and sky‑cycles. Okay, there’d be problems and we’d need an AI-boosted Air Traffic Control agency. The military would be all over the idea. But all that’s way down the road, so to speak. I don’t understand how that puts Ralphie in immediate danger and why would a tunnel help?”

“Not anti-gravity, directed gravity. Gravity’s built into the structure of spacetime. Gravity can’t be blocked, but it can be shifted. The only way to weaken it in one location is to make it stronger somewhere else. Suppose Cochrane had first powered‑up his device on the ground in the open air. Depending on which way it was pointed, either he’d have been crushed between rising magma and down‑falling air, or…”

“I’ll tell Ralphie to re‑configure his gadget. Thanks for the warning.”

~~ Rich Olcott

  • Thanks, Alex, for inspiring this.

Symmetry And The Loopholes

On By rolcottIn Cosmology, Mathematics, UncategorizedLeave a comment

“So, we’ve got geometry symmetry and relativity symmetry. Is that it, Sy?”

“Hardly, Al. There’s scores of them. Mathematics has a whole branch devoted to sorting and classifying the operations and how they group together. Shall I list a few dozen?”

“Ah, no, don’t bother, thanks. You got one I’d recognize?”

“How about charge symmetry? Flip an electron’s negative charge and you’ve got a positron that has exactly the same mass and the same interaction with light waves. OK, positrons move opposite to electrons in a magnetic field which is how their existence was confirmed, but charge is s a fundamental symmetry for normal matter.”

“Oh, right, charge is a piece of that CPT symmetry you hung your anti‑Universe story on. Which reminds me, you never said what the ‘P’ stands for.”

“Parity, as in Charge‑Parity‑Time. Before you ask, ‘parity‘ is left-right symmetry. Parity symmetry says you can replace ‘clockwise‘ with ‘counterclockwise‘ in a system and the equations describing the system will give perfectly good predictions. Time symmetry is about time running forward or backward. The equations are happy either way. The CPT theorem says the three symmetries are solidly tied together — you can’t flip one without the other two tagging along. If some process emits particle X with clockwise spin, there’s some equivalent process that soaks up an anti-X if it’s spinning counterclockwise. Very firm theorem, lots of laboratory evidence for it from electromagnetism and the nuclear strong force. But.”

“But?”

“But Chien‑Shiung Wu did an experiment that showed the nuclear weak force doesn’t always obey CPT rules. Her worked proved we live in a handed Universe. She should have gotten a Nobel for that, but it was last century and the Nobel Committee was men‑only. Two theory guys copped the prize that should have gone to the three of them. The theory guys protested but the Committee ignored Wu anyway. Sometimes things aren’t fair.”

“Tell me about it. So the theory’s got a loophole?”

“Apparently, but to my knowledge no‐one’s found it. Some string theories claim to hint at an explanation but that’s not much help, considering.”

“Huh. Could the loophole maybe be an example of symmetry breaking?”

“Very good question. I think it’s a qualified probably but that’s a guess.”

“Sy, I think that’s the wishy-washiest you’ve ever been.”

“One of my rules is, when you’re going out on a limb be sure you’re properly roped to the tree. In this case I’m generalizing from a single sample.”

“You’re gonna tell me, right?”

   Professor Higgs presents
       the Higgs Bozo.

“Just the bare outline because I don’t want to get into the deep weeds. Back in the 1960s Physics was in trouble because the nuclear strong force particles that bind the nucleus together were found to have mass and move slowly. Strong‑force theory at the time said they should be massless and move at lightspeed. The theory depended on part of the potential energy varying with the symmetry of a circle. Then Higgs—”

“The Higgs Boson guy?”

“That’s him. Anyway, he published a three‑page paper showing that those binding particles aren’t controlled solely by the nuclear strong force. Because they have a charge they also engage with the electromagnetic field. Electromagnetism is a lot weaker than the strong force, but it’s strong enough to deform the theory’s circle into an ellipse. Breaking the circular symmetry in effect gives the particles mass and slows them down.”

“So where’s the boson come in? I thought it’s what makes mass for everything.”

“Absolutely not, probably. The protons and neutrons have plenty of mass on their own, thank you very much. It’s only those strong-force particles that gain mass, less than 1% of the nucleus total. But the whole story is a great example of how making a system less symmetrical, even a little bit, can completely change how it operates. We think that’s what drove the Big Bang’s story. The early Universe was so dense and hot it was a perfectly symmetrical quark soup — chaos all the way down. Space expansion opened successive symmetry loopholes that permitted layers of structure formation.”

<looking at hands> “I don’t feel unsymmetrical.”

“Trust me, deep down you are.”

~~ Rich Olcott

Reflection, Rotation And Spacetime

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

“Afternoon, Al.”

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

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

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

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

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

“I can try. What’s the something?”

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

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

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

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

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

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

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

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

“Symmetry’s not just math then.”

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

“Einstein didn’t do the math?”

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

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

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

~~ Rich Olcott

Time And The Egg

On By rolcottIn Cosmology, UncategorizedLeave a comment

I unlock my office door and there’s Vinnie in the client chair flipping a coin from hand to hand. If my building ever switches to digital locks he’d take it as a challenge. “Morning, Vinnie.”

“Morning, Sy. Been reading your multiverse series and something you said bothered me.”

“What’s that?”

“Back when you wrote up your anti-Universe idea that some other group had come up with first—”

“Don’t remind me.”

“—you mentioned how time going backwards makes for negative energy, like that’s obvious. It ain’t obvious to me.”

“Okay … Ah. What word keeps coming up in our black hole discussions?”

“Geez, frames again? Universes ain’t black holes.”

“Don’t be so sure. Suppose there’s a black hole Event Horizon that encloses our entire Observable Universe. An Event Horizon’s diameter depends on how much mass it has inside. Astronomy’s given us an estimate of how much normal matter our Observable Universe contains. I adjusted that number upward to account for the expected quantity of dark matter plus dark energy’s equivalent mass. When I plugged that grand total into Schwarzchild’s formula for the diameter of an Event Horizon, the result was about seven times wider than what we can observe. We could be inside a huge black hole but we’ll never know either way.”

“Whoa! Wouldn’t we notice a drift towards the singularity at its middle?”

“Not if we’re reasonably far out or if the drift rate is tiny compared to the slow chaos of intergalactic space. Mind you, it took us centuries to develop the technology that told us we’re inside the Milky Way and two‑thirds of the way out from the core.”

“We used frames for thinking about going really fast or being outside a black hole. Now we’re inside one or maybe not. How’s frames gonna help us with that?”

“Well, not the inertial frames where we compared relativistic observers, but the idea is similar. A traveler in an intense gravity field experiences slower time in its inertial frame than a distant partner does in theirs. Clocks appear to run weirdly if they’re compared between separate frames whose relative velocities are near lightspeed.”

“Yeah, that’s what we said.”

“Now picture two observational frames, one here in our Universe and one in the anti‑Universe if there is one. Time in the two frames flows in opposite directions away from the Big Bang between them. The two‑frames notion is a convenient way to think about consequences. Negative energy is one.”

“Now we’re getting somewhere. So give.”

“Well, what does energy do?”

“It makes things happen.”

“Negative energy does, too, considered from inside its frame. Looking from our frame, though, negative energy makes things unhappen. This spoon on our table has gravitational potential energy relative to the floor, right?”

“Yeah, you push it over the edge it’ll fall down.”

“But looking from our frame at a similar situation in the anti‑Universe running on anti‑time, an anti‑spoon on its floor has negative gravitational potential energy. We’d see it fall up to its table. Make sense?”

“Gimme a minute.” <pause> “Kinda hard to visualize but I’m starting to get there.” <longer pause> “Alright, you know I hate equations but even I know about Einstein’s E=mc². That c² is a square so it’s always positive so if E is negative then the mass gotta be negative, too.”

“From our frame all mass in the anti‑Universe looks negative. Negative mass would attract negative mass just like positive mass attracts positive mass here. Gravity in the anti‑Universe would work exactly the same way as our gravity does, so where’s the problem?”

“Gimme another minute.” <more pausing> “Suppose that spoon was an anti‑egg. You’re sayin’ when it goes splat over there, we’re gonna see it unsplat? Unsplatting uses up entropy. How about the ‘Entropy always increases‘ rule?”

“Right on the unsplat, wrong on the other. The full statement of Thermodynamics’ Second Law says that entropy never decreases in an isolated system. You can’t get much more isolated than being a separate Universe — no inputs of energy or matter from our Universe or anywhere else, right? From our frame, it looks like the anti‑Universe flipped the Second Law but that’s only because we’re using the wrong clock.”

~~ Rich Olcott

Noodles or A Sandwich?

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

“Wait, Sy, your anti-Universe idea says there are exactly two um, sub‑Universes. Even the word ‘multiverse‘ suggests more than that.”

“You’re right, Susan, most of the multiverse proposals go to the other extreme. Maybe the most extreme version grew in reaction to one popular interpretation of quantum theory. Do you know about the ‘Many Worlds‘ notion?”

“Many Worlds? Is that the one about when I decide between noodles for lunch or a sandwich, the Universe splits and there’s one of me enjoying each one?”

“That’s the popular idea. The physics idea is way smaller, far bigger and even harder to swallow. Physicists have been arguing about it for a half‑century.”

“Come again? Smaller AND bigger?”

“Smaller because it’s a quantum‑based idea about microscopic phenomena. Doesn’t say anything about things big enough to touch. Remember how quantum calculations predict statistics, not exact values? They can’t give you anything but averages and spreads. Einstein and Bohr had a couple of marquee debates about that back in the 1930s. Bohr maintained that our only path to understanding observations at the micro‑scale was to accept that events there are random and there’s no point discussing anything deeper than statistics. Einstein’s position was that the very fact that we’re successfully using an average‑based strategy says that there must be finer‑grained phenomena to average over. He called it ‘the underlying reality.’ The string theory folks have chased that possibility all the way down to the Planck‑length scale. They’ve found lots of lovely math but not much else. Hugh Everett had a different concept.”

“With that build‑up, it’d better have something to do with Many Worlds.”

“Oh, it does. Pieces of the idea have been lying around for centuries, but Everett pulled them all together and dressed them up in a quantum suit. Put simply, in his PhD thesis he showed how QM’s statistics can result from averaging over Universes. Well, one Universe per observation, but you experience a sequence of Universes and that’s what you average over.”

“How can you show something like that?”

“By going down the rabbit hole step by step and staying strictly within the formal QM framework. First step was to abstractify the operation of observing. He said it’s a matter of two separate systems, an observer A and a subject B. The A could be a person or electronics or whatever. What’s important is that A has the ability to assess and record B‘s states and how they change. Given all that, the next step is to say that both A and B are quantized, in the sense that each has a quantum state.”

“Wait, EACH has a quantum state? Even if A is a human or a massive NMR machine?”

“That’s one of the hard‑to‑swallows, but formally speaking he’s okay. If a micro‑system can have a quantum state then so can a macro‑system made up of micro‑systems. You just multiply the micro‑states together to get the macro‑state. Which gets us to the next step — when A interrogates B, the two become entangled. We then can only talk about the combined quantum state of the A+B system. Everett referred to an Einstein quote when he wrote that a mouse doesn’t change the Moon by looking at it, but the Moon changes the mouse. The next step’s a doozy so take a deep breath.”

“Ready, I suppose.”

“B could have been in any of its quantum states, suppose it’s #10. After the observation, A+B must be an entangled mixture of whatever A was, combined with each of B‘s possible final states. Suppose B might switch to #42. Now we can have A+B(#42), separate from a persisting A+B(#10), plus many other possibles. As time goes by, A+B(#42) moves along its worldline independent of whatever happens to A+B(#10).”

“If they’re independent than each is in its own Universe. That’s the Many Worlds thing.”

“Now consider just how many worlds. We’re talking every potential observing macro‑system of any size, entangled with all possible quantum states of every existing micro‑system anywhere in our Observable Universe. We’re a long way from your noodles or sandwich decision.”

“An infinity of infinities.”

“Each in its own massive world.”

“Hard to swallow.”

~~ Rich Olcott

A Two-Way Stretch, Maybe

On By rolcottIn Cosmology, Uncategorized1 Comment

“Okay, Moire, I guess I gotta go with the Big Bang happening, but I still have a problem with it making everything come from a point full of nothing.”

“Back at you, Mr Feder. I have problems with your problem. To begin with, forget about your notion of a point with zero size. There’s some reason to think the Bang started with an event sized on the order of the Planck length, 10-35 meter. That’s small, but it’s not zero.”

“I suppose, but with the whole mass of the Universe crammed in there, ain’t that a recipe for the ultimate black hole? Nothing could get outta there.”

“Nothing needs to. What’s inside is already everything, remember? Besides, there isn’t an outside — space simply doesn’t exist outside of the spacetime the Bang created. Those bell‑shaped ‘Evolution of The Universe‘ diagrams are so misleading. I say that even though I’ve used the diagram myself. It’s just a graph with Time running along the central axis and Space expanding perpendicular to that. People have prettied it up to make it cylindrical and added galaxies and such. The lines just represent how much Space has expanded since the Bang. Unfortunately, people look at the bell as a some kind of boundary with empty space outside, but that’s so wrong.”

“No outside? Hard to wrap your head around.”

“Understandable. Only physicists and mathematicians get used to thinking in those terms and mostly we do it with equations instead of trying to visualize. Our equations tell us the Universe expands at the speed of light plus a bit.”

“Wait, I thought nothing could go faster than the speed of light.”

“True, nothing can traverse space faster than light or gravity, but space itself expands. At large distances it’s doing that faster than light. We actually had to devise two different definitions of distance. ‘Co‑moving distance‘ includes the expansion. ‘Proper distance‘ doesn’t. In another couple billion years, the farthest things we can see today will be co‑moving away so fast that the photons they emit will be carried away faster than they can fly towards us. Those objects will leave our Observable Universe, the spherical bubble that encloses the objects whose light gets a chance to reach us.”

“My head hurts from the expanding. Get back to the Bang thing ’cause it was small. Too small to hold atoms I guess so how can it explode to be everything?”

“‘Expand’, not ‘explode‘ — they’re different — but good guess. The Bang’s singularity was smaller than an atom by at least a factor of 1024, but conditions were far too hot in there for atoms to exist, or nuclei, or even protons and neutrons. Informally we call it a quark soup, which is okay because we think quarks are structureless points that can cram to near‑infinite density. We don’t yet know enough Physics for good calculations of temperature, density or much of anything else.”

“That’s a lot of energy, even if it’s not particles. Which is what I’m getting at. I keep hearing you can’t create energy, just transform it, right? So where did the energy come from?”

“That’s a deep question, Mr Feder, and we don’t have an answer or hypothesis or even a firm guess. It gets down to what energy even is — we’re just barely nibbling at the edges of that one. One crazy idea I kind of like is that creating our Universe took zero energy because the process was exactly compensated for by creating an anti‑Universe whose total anti‑energy matches our total energy.”

“Whaddaya mean, anti‑Universe and anti‑energy?”

<deep breath> “You know an atom has negatively‑charged electrons bound to its positively‑charged nucleus, right? Well, the anti‑Universe I’m thinking of has that situation and everything else reversed. Positive electrons, negative nucleus, but also flipped left‑right parities for some electroweak particle interactions. Oh, and time runs backwards which is how anti‑energy becomes a thing. Our Universe and my crazy anti‑Universe emerge at Time Zero from the singularity. Then they expand in opposite directions along the Time axis. Maybe the quarks and their anti‑quarks got sorted out at the flash‑point, I dunno.”

“So there’s an anti‑me out there somewhere?”

“I wouldn’t go that far.”

~~ Rich Olcott

Everything Everywhere All at Once

On By rolcottIn Cosmology, UncategorizedLeave a comment

It’s either late Winter or early Spring, the weather can’t make up its mind. The geese don’t seem to approve of my walk around the park’s lake but then I realize it’s not me they object to. “Hey, Moire, wait up, I got a question for you!”

“Good morning, Mr Feder. What can I do for you?”

“This Big Bang thing I been hearing about. How can it make everything from nothing like they say?”

“You’re in good form, Mr Feder, lots of questions buried within a question.”

“Oh yeah? Seems pretty simple to me. How do we even know it happened?”

“Well, there you go, one buried question up already. We have several lines of evidence to support the idea. One of them is the CMB.”

“Complete Monkey Business?”

“Very funny. No, it’s the Cosmic Microwave Background, long‑wavelength light that completely surrounds us. It has the same wavelength profile and the same intensity within a dozen parts per million no matter what direction we look. The best explanation we have for it is that the light is finally arriving here from the Big Bang roughly 14 billion years ago. Well, a couple hundred thousand years after the Bang itself. It took that long for things to cool down enough for electrons and protons to pair up as atoms. The photons had been bouncing around between charged particles but when the charges neutralized each other the photons could roam free.”

“Same in all directions so we’re in the center, huh? The Bang musta been real close‑by.”

“Not really. Astronomers have measured the radiation’s effects on a distant intergalactic dust cloud. The effect is just what we’d expect if the cloud were right here. We’re not in a special location. From everything we can measure, the Bang happened everywhere and all at once.”

“Weird. Hard to see how that can happen.”

“We answered that nearly a century ago when Edwin Hubble discovered that there are other galaxies outside the Milky Way and that they’re in motion.”

“Yeah, I heard about that, too, with everything running away from us.”

“Sorry, no. We’re not that special, remember? On the average, everything’s running away from everything else.”

“Whaddaya mean, ‘on the average‘? Why the wishy-washy?”

“Because things cluster together and swirl around. The Andromeda galaxy is coming straight toward us, for instance, but it won’t get here for 5 billion years. The general trend only shows up when you look at large volumes, say a hundred million lightyears across or bigger. The evidence says yeah, everything’s spreading out.”

“But how can everything be moving away from everything? You run away from something, you gotta be running toward something else.”

“That’d be true if your somethings are all confined in a room whose walls don’t move. The Universe doesn’t work that way. The space between somethings continually grows new space. The volume of the whole assemblage increases.”

“Is that why I just hadda buy new pants?”

“No, that’s just you gaining weight from all that beer and bar food. The electromagnetism that holds your atoms and molecules together is much stronger than what’s driving the expansion. So is the gravitation that holds solar systems and galaxies together. Expansion only gets significant when distances get so large that the inverse square laws diminish both those forces to near zero.”

“What’s this got to do with the CMB?”

“The CMB tells us that the Bang happened everywhere, but expansion says that at early times when stars and galaxies first formed, ‘everywhere‘ was on a much smaller scale than it is now. Imagine having a video of the expansion and playing it backwards. Earendel‘s the farthest star we’ve seen, but if we and it existed 12 billion years ago we’d measure it as being close‑by but still all the way across the observable Universe. Carry that idea the rest of the way. The Big Bang is expansion from a super‑compressed everywhere.”

“Okay, what’s driving the expansion?”

“We don’t know. We call it ‘dark energy‘ but the name’s about all we have for it.”

“Aaaa-HAH! At last something you don’t know!”

“Science is all about finding things we don’t know and working to figure them out.”

~~ Rich Olcott