Only A Bird in A Quantum Cage

“What’s another quantum rule, Uncle Sy?”

“Uhh…  Oh, look what the birds are doing now, Teena — flying back and forth between those two fields.”murmuration dipole 1“I think one side looks like a whale jumping out of the water, and the other side looks like the tail end of a buffalo or something.”

“Well, I can’t argue with that.  Look, though — the murmuration’s acting like it’s caught between two barriers of some kind.  That reminds me of another rule.  When you’re one of those tiny quantum things, it matters if you’re caught between barriers.”

“I’d want to be free so I could go wherever I want to.”

“Freedom’s nice for people but it must be boring for quantum things.  The rule says that a particle that doesn’t have any barriers just goes in a straight line forever and ever.  No stopping for lunch, never anyone to talk to, just traveling on and on.”

“Yeah, that’d be boring, all right.  What’s the rule say for when there’s barriers?”

“It depends on the barriers, what their shapes are and how far apart they are.  The general situation, though, is that there’s usually some forbidden regions, places where the particle can’t go.”

“Oooo, forbidden.  So spooky.  What happens to the particles who go there anyway?  Does something catch them and do bad things to them?”

“You’ve been watching too many horror movies.  No doing bad things but no trying to go into a forbidden area anyway.  Physics particles don’t have choice in the matter — they just can’t enter those places.  Almost can’t.”

“I heard ‘almost.’  Are you being sneaky?”

“No, just trying to keep things simple.  There’s something called ‘tunneling,’ where a particle that’s on one side of a barrier can sometimes somehow get to the other side of the barrier without going through it.  It’s one of the big puzzles in quantum mechanics.”

“Can’t it climb over, like I climb over fences?  (Shh, don’t tell Mommy.)”

“I suspect she already knows, Mommies are good at that, and I’m sure she’s praying that you’re being careful about which fences to climb and how you do it.”

“I am.  I only climb friendly fences that don’t have angry dogs behind them.”

“Good strategy, I feel better now.”

“If quantum thingies are even smaller than water-bear eggs, what do you make the barriers out of?”

“People don’t make the barriers, they’re just there, part of how the Universe works.  Um… Those little blocks you have that push each other away or pull together depending on how you point them…?”

“My rainbow blocks!  I love them.  Sometimes it’s hard to build something with them because you have to set one in a space just right or it’ll jump out.”

“Mm-hm.  Well, that push-or-pull force is called magnetism, and some of the barriers are made of that.”

“But that’s not a real thing!”

“Not something you can pick up, no, but the quantum things feel it and that’s what counts.  If the Universe didn’t have magnetism and forces related to it, we wouldn’t have rocks or stars or us.”

“I guess I’m happy that the barriers give quantum thingies places they can’t go.”

‘Just to make things more complicated, a lot of the forbidden places aren’t even where the barriers are.”

“Huh?”

“Like I said, it depends on the shape of the barriers.  If you’ve got two that face each other, there could be a forbidden place maybe in the middle, or two forbidden places a third of the way from each side, or three or four, all the way up.  And here’s a weird case that’s really important.  Ready to stretch your brain?”

“Just a minute … NNGGGGGH!  OK, I’m ready.”

“For an atom one of those barriers is infinitely far away.”

Infinitely??!?  My brain doesn’t stretch that far!”

“How about really, really far and let it go at that?  Anyway, atom barriers give us colors.”

“Now my head hurts.”

“Oh dear, better let your brain unstretch.  Hey look, the birds are flying off to roost in the woods ’cause it’s getting dark.  And it smells like your Mommy’s got dinner ready.  Time to go inside.”

“Mommy, can Uncle Sy stay for dinner with us?”

~~ Rich Olcott

 

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What Are Quantum Birds Made Of?

“Do quantum thingies follow the same rules that birds do, Uncle Sy?”

“Mostly not, Teena.  Some quantum rules are simple, others are complicated and many are weird.”

“Tell me a simple one and a weird one.”

“Hm… the Principle of Correspondence is simple.  It says if you’ve got a lot of quantum things acting together, the whole mishmash acts by the same rules that a regular-sized thing that size would follow.  If all those birds flew in every direction there’s no flock to talk about, but if they fly by flock rules we can talk about how wind affects the flock’s motion.”

“It’s a murmuration, Uncle Sy.”

“Correction noted, Sweetie.”

“Now tell me a weird one.”

“There’s the rule that a quantum thing acts like it’s in a specific place when you look at it but it’s spread out when you’re not looking.”

“Kittie does that!  She’s never where you look for her.”

“Mm, that’s kind of in the other direction.  We see quantum particles in specific somewheres, not specific nowheres.  The rule is called wave-particle duality and people have been trying to figure out how it works for a hundred years.  Let’s try this.  Put your thumb and forefinger up to your eye and look between them at the blue sky.  Hold your fingers very close together but don’t let them touch.  What do you see?”

“Ooo, there’s stripes in between!  It looks like my finger’s going right into my thumb, but I can feel they’re not touching.  Hey, it works with my other fingers, too, but it hurts if I try it with my pinkie.”

“Then don’t do it with your pinkie, silly.  The stripes are called ‘interference’ and only waves do that.  You’ve watched how water waves go up and down, right?”

“Sure!”

“When the high part of one wave meets the low part of another wave, what happens?”

“I guess high and low make middle.”

“Good guess, that’s exactly right.  That little teeny space between your fingers lets through only certain waves.  You see light where the highs and lows are, dark where the waves middle out.”

“So light’s made out of waves, huh?”

“Well, except that scientists have done lots of experiments where light behaves like it’s made out of little particles called photons.  The funny thing is, light always acts like a wave when it’s traveling from one place to another, but at both ends of the trip it always acts like photons.  That’s the big mystery — how does it do that?”

“You know how it works, don’tcha, Uncle Sy?”

“Only kinda sorta, Teena.  I think it has to do with the idea of big things made out of little things made out of littler things.  Einstein — wait, you know who Einstein was, right?”

“He was the famous scientist with the big hair.”

“That’s right.  He and another scientist had a big debate over 80 years ago.  The other scientist said that when quantum things make patterns, like those stripes you’re looking at, the patterns are all we can know about them.  Einstein said that there has to be something deeper down that drives the patterns.”

“Who won the debate?”

“At the time most people thought that the other man had, but philosophies change.  Since that time lots of people have followed Einstein’s thinking.  Some of the theories are pretty silly, I think, but I’m betting on birds made out of birds.”

“That’s silly, too, Uncle Sy.”

“Maybe, maybe not, we’ll see some day.  It starts with what you might call ‘the smallness quantum,’ though it’s also called ‘the Planck length‘ after Mr Planck who helped invent quantum mechanics.  The Planck length is awesomely small.  It’s as much smaller than us as we are smaller than the whole universe.”

“But there’s lots of things bigger than we are.”

“Exactly.  We’re smaller than whales, they’re smaller than planets, planets are smaller than suns, and galaxies, and on up.  But we don’t know near as many size scales in the other direction – us and bacteria and atoms and protons and that’s about it.  I think there’s plenty of room down there for structures and chaos we’ve not thought of yet.”

“Like birds in murmurations.”

“Mm-hmm.”Bird made out of birds 1

~~ Rich Olcott

Teena And The Quantum Birds

“Hey, Uncle Sy, what’s quantum?”

“That’s a big question for a small person, Teena.  Where’d you hear that word?”

“You and Mommy were talking and you said that something had to do with quantum mechanics.  I know car mechanics work on cars so I want to know what the quantum mechanics work on.”

“That’s a fun question, Sweetie, because there actually is a kind of car called a Quantum.  Not very many of them and they’re made in England so you don’t often see one here.  But the quantum mechanics we were talking about is completely different.  I’ll take it one word at a time, OK?”

<sigh> “OK, but let’s sit on the porch swing, I can tell this will take a while.”

“Oh, it’s not going to be that bad.  You know what mechanisms are, right?”

“Um.. they’re not like people or animals and they’re not like my tablet thingie…. They’ve got gears and things.”

“Good enough.  A big part of physics is thinking about how mechanisms work and that’s called ‘mechanics.’  There’s lots of different kinds of mechanisms.  Each kind has a different kind of mechanics, like ‘celestial mechanics’ which is thinking about how stars and planets move, and ‘fluid mechanics’ which is thinking about how liquids and gases move.  With me so far?”

“So quantum mechanics is thinking about how quantums move.  But what’s a quantum?”

“Quantum isn’t a thing, it’s a set of rules that add up to be a theory.  The first rule is, it only applies to things that are very, very small.  That’s what the word ‘quantum’ has come to mean — the smallest possible amount of something.  So quantum rules apply to quantum-sized things.”

“As small as my water bears?”

“Much smaller.  Things that are as small compared to a water bear as a water bear egg is small compared to you.  Things like molecules and atoms, and those are made of lots of parts that are even way smaller.”

“Ooo, that’s teeny.  How do you even see them?”

“Well, you don’t.  They’re far too small to see even with a microscope.  It’s worse — if you did try to see an atom’s parts, any light you could shine on them would move them around so they’re not where they were when you started to look.”

“Then how do the quantum mechanics people learn about them?”

“Umm…  Ah! See that flock of birds flying past?”

“Mommy says they’re starlings but I think they’re blackbirds.”

“Could be either or both, it’s hard to tell when they’re in the air like that.  Sometimes the two kinds flock together.  If it’s a flock of starlings, the flock is called a murmuration, which is one of my favorite words.”

“Oh, that’ll be one of my favorites now, too.  Murmuration, mmmurmuration, mmmm.  I love  ‘M‘ words.”

“Anyway, can you see what direction any one bird is flying?”

“No, there’s too many and they go back and forth and it’s too confusing and I like the shapes the whole murmuration makes.”

“But can you point to the middle of it and see how the pattern moves?”

“It’s right the— ooo, look, it did a spiral!”

“Murmurations are sorta like the kind of thing the quantum mechanics people work with.  They look at lots and lots of quantum-size things to see how the typical ones and the special ones behave.  Then they try to work out what the behavior rules are.  Sometimes the rules are really simple, like the rules the birds use.”

“Birds use rules?  I thought they could fly wherever they wanted to.”

“Sometimes they do, but if they’re flying in a murmuration they definitely follow rules.  Most of them.  Most of the time.  If I were one of those birds, I’d stay about the same distance from each of my neighbor birds, I’d usually fly in about the same direction as my neighbors are flying, and I’d also aim at about the middle of the flo— murmuration.  Scientists have found that just those three rules account for most of how a murmuration behaves.  Cool, huh?”

“Simple rules for bird brains, that’s funny!”

“But look at the beautiful shapes those simple rules make.”Murmuration 1

~~ Rich Olcott

Teena Meets The Eclipses

“Don’t look up until it suddenly gets really dark, Teena.  I’ll tell you when it’s time.”

“OK, Uncle Sy.  Oooo, look at the house where our tree makes a shadow!  It’s all over crescents!”

“Yep, wherever leaves overlap to make a pinhole, it’s like the one we made in our cardboard.  See, those crescents are just like the one our pinhole beams onto the sidewalk.”

“Yeah.  ‘Cause it’s the same Sun, right?”

“Sure is.”

“Are other little kids seeing the eclipse all over the world?  They’ve got the same Sun, too.”

“No, just the ones who happen to be on the shadow stripe that the Moon paints on the Earth.”

“How many kids is that?”

“Hard to tell.  Some families live where the shadow passes through, some families travel to be there, lots of other families just stay where they are.  No-one knows how many of each.  But we can make some not-very-good guesses.”

“The crescent’s going so slow.  Let’s make guesses while we’re waiting.”

“OK.  Let’s start by imagining that all the world’s people are spread evenly over the land and sea.”

“Even on the ocean?  Like everyone has a little boat?”

“Yep, and sleds or whatever on polar ice, people everywhere.  In our city there are eight blocks to a mile, so if we spread out the people there’d be one person every other block.”

“Every other block.  Like just on the black squares on our checker board.”

“Uh-huh.  The Moon’s shadow today will be a circle about 80 miles across and it’ll travel about 2500 miles across the whole country.  The stripe it paints would cover about 6½ million spread-out people.  Maybe 10 million if you count the people in little boats, ’cause the eclipse starts and ends over the ocean.”Local eclipses

“Lots of people.”

“Yes, but only about one person out of every thousand people in the world.”

“We’re pretty lucky then, huh?”

“Oh, yeah.”

“Are there eclipses on other planets?”

“Of a sort, but only for planets that have a moon.  Poor Mercury and Venus don’t have moons so they never see an eclipse.”

“Aww. … Wait — you said ‘of a sort.’  Are there different kinds of eclipses?”

“You’re very alert this morning.  And yes, there are.  Two that get the publicity and two that we never see on Earth.  It has to do with perspective.”

“Per … perspec…?”

“Perspective.  The word originally meant very careful looking but it’s come to be about how things look from a particular point of view.  See that tree across the street?”

“Yeah.”

“Think your hand is bigger than the tree?”

“Of course not.  I climb that tree.”

“OK, put your hand between your eyes and the tree.”

“Oh!  My hand covers the whole tree!”

“Yup.  Nearer things look big and farther things look small.  That’s perspective.  Eclipses are all about perspective.”How big is the Sun

“How come?”

“The perspective principle works in the Solar System, too.  If you were to travel from Earth to Mars to Jupiter and so on, the Sun would look smaller at each planet.”

“Like the far-away trees look smaller than the close trees.  But what does that have to do with eclipses?”

“A planet gets an eclipse when one of its moons comes between it and the Sun.  That’s what’s happening right now here.  Our Moon is moving between us and the Sun and blocking its light.”

“But I don’t see the Moon, just the carved-out piece.”

“That’s because we’re looking at the unlit side of the Moon.  It’s so dim compared to the rest of the sky.  Anyway, the Moon’s width we see is just about the same as the Sun’s width.  The moons on the other planets don’t match up that well.  On Mars, for instance, its moon Phobos appears less than half the width of the Sun even though the Sun appears only 2/3 as wide as we see it.  Phobos can never cover the Sun entirely, so no true eclipse, just a transit.”

“Can the planet’s moon be bigger?”

“Sure.  On Jupiter, Europa’s width completely blocks out the Sun.  That’s called an occultation.  You can look up now.  Jupiter people can never see that corona.”

“Oooooo, so pretty.  We’re lucky, aren’t we?”

“In more ways than you know, sweetie.”

~~ Rich Olcott

Goldilocks Zone and The Three Gazillion Bears

“Tell me a bedtime story, Uncle Sy.”

“OK, Teena, what kind of story?”

“One with bears in it.  Nice bears.”

“Hmm…  How about ‘Goldilocks Zone and The Three Gazillion Bears’?”

“Gazillion?  Is that what kind of a bear they are?”

“No, that’s a number word.  It means ‘more than you could ever hope to count.’  Like a million but way way more.”

“But if you can’t count them, how do you know there are three times that many?”

“You’ll see, have patience.”

“Little girls don’t have patience, Uncle Sy, I wanna hear the story.  Wait, water bears?”

“Mm-hm, they’re a different kind of bear.”

“What’s different about them, and what do they do with water?  I bet they swim.”

“Why yes, they do.  In fact, they spend most of their time in water or at least being wet.  Another thing that’s special about them is that they’re tiny, about the size of the smallest dot you can see on your Mommy’s computer screen here.”
waterbear 1“If they’re so small, why are they called bears?”

“Take a look.  Doesn’t she look kind of like a nice bear?”

“She’s got too many legs.”

“She’s got just the right number for water bears.”

“And she’s green.”

“Well, yes, but the picture’s kind of pretend and doesn’t show proper colors.  She’s so small she’s almost transparent.  She eats particles of algae and such, so maybe in real life she might be sort of green.”

“I like the way she’s smiling.  She reminds me of …  the fat man in the Laurel-n-Hardy movie you showed me last Saturday.”

“Oliver Hardy?  Yeah, I can see that.  Except the smiley bit is actually a wrinkle.  Her mouth is the round thing that looks like a nose.”

“That’s silly.  If her nose is her mouth how can she breathe?”

“Through her skin.  Animals can do that if they’re very small.”

“How else is she different?”

“Well, her kind’s one of Earth’s oldest animals.  Scientists have found water bear fossils over 500 million years old, twice as old as the oldest dinosaur.”

“Older than dinosaurs!”

“But the big thing and the big puzzle is, they’re amazingly rugged little beasties.  They live all over the world — high on mountaintops, at the bottom of the sea, next to ice at the South Pole and next to boiling hot springs.  In experiments, water bears have survived doses of chemicals and radiation that would kill most other creatures.  Astronauts on the ISS even exposed dried-out water bears to the vacuum of space.  The little guys just got happy-active again when they were brought back inside and dunked in some water.”

“What’s the puzzle?”

“Why are they so tough?  They make special molecules that protect them against dehydration and radiation and toxins even though they live in wet environments that don’t get irradiated and rarely get poisoned.  Fish and insects that evolved in lightless caves stopped using energy to make eyes they don’t need.  Why or even how have water bears held onto all that specialized protective DNA for hundreds of millions of years?”

“Does anybody know the answer?”

“Nope.  Some people have guessed that because water bears can survive exposure to space, maybe they came to Earth from another planet somewhere.  Maybe some advanced civilization sprayed water bears out into the Universe to spread life around.  Doesn’t that sound spooky?”

“Ooohh, yeah.  I like that.  Water bears from space!”

“But it gets better.  Maybe there’s different kinds of water bears for different kinds of planets.  That’s where Goldilocks Zones come in.  What did Goldilocks say about the porridge?”

“This bowl’s too hot and this bowl’s too cold, but this bowl is j-u-s-t right!”Water bears and planet“Yup, and that’s one way astronomers can classify planets.  Earth’s in the Goldilocks Zone for liquid water, essential for life as we know it.  Saturn’s moon Titan might support some other kind of life in its cold hydrocarbon seas.  If that’s the case, there’d be a much colder Goldilocks Zone for that kind of life.  Maybe there’s another, hotter Goldilocks Zone for life that’s happy in molten silica.  And maybe there’s water bears designed for each kind of Goldilocks Zone.”

“Mommy, Uncle Sy’s being silly again.”

“Nighty-night, Teena-girl.  Sweet dreams.”

“Nighty-night.”

~~ Rich Olcott