Baseball And The Virtual Particle

Al was pouring my mugful of his morning blend (“If it doesn’t wake you up we’ll call the doctor“) when Jeremy stepped into the counter.  “Hi, Mr Moire.  I’m still trying to get my head around that virtual particle thing.  Hi, Al, a large decaf, please, double sugar, three creamers.  It looks like the shorter amount of time you give a particle to happen, the bigger it can get, but that doesn’t make sense because I’d think the longer you wait the more likely it’s gonna happen.  Thanks, Al.”

“Take a breath to blow on that coffee, Jeremy, or you’ll burn your tongue.  Hmm…  Word is your batting average is running about 250 these days.  That right?”

“Yessir.  I didn’t know you’re keeping track.”

“Keeping my ears open is part of my job.  So you’re hitting about once every four at-bats.  That gives Coach an estimate of when you’ll get your next hit.  What’s your slugging average?”

“What’s a slugging average?”

“Your total number of batted-on bases, divided by your at-bats, times a thousand ’cause sports writers don’t do decimal points.  You get one count in the numerator for a single, two for a double and so on.”

“Lemme think.  If I’m doing 250 overall and about half are singles and the other half are doubles that’d give me an SA of … about 375.”

“Pretty good.  So does that number tell Coach anything about when to expect another double?”

“Mmm, no, but what does that have to do with my virtual particle question?”

“In each case you’ve got a pair of statistics that tell you some things and hide other things.  Batting averages and your wait-time notion are about when to expect an event of some sort to occur.  You could hit another single or you could tag a homer — all Coach knows is that you should be able to get on base about once every four at-bats.”

“What about the other statistics?”

“They’re the flip side, sort of.  You could think of the SA as batting potential.  If you hit homers all the time your SA would be 4000.  If you whiff every pitch your SA would be zero.  Anything between those extremes tells Coach something about your productivity but nothing about when you’re going to produce.  Energy uncertainty works the same way for virtual particles.  If you’re doing long-duration energy evaluations you can be pretty sure that any single measurement will be close to the long-term average.  You might possibly see a significant deviation from that average but only if you check just the right brief interval.”Virtual baseball

“And for the particles in that empty space?”

“If you’re looking long-term, no particles.  That’s what ’empty’ means.  When there’s definitely nothing in a volume of space it makes sense to say its energy is zero because particles have mass and therefore embody energy.  But a particle might show up and go away after a very brief interval without significantly affecting that long-term average.  Quantum theory doesn’t say it will show up, just that it might.”

“So does it?”

“Oh yes, in space, in the lab and in commerce.  One explanation for your cell phone’s NFC function hinges on virtual radio-frequency photons being exchanged between devices.”

“Wait.  If a virtual particle shows up in that empty space, then it’s not empty any more and its energy isn’t zero any more, is it?”

“You’ve just discovered one aspect of zero-point energy, the quantum prediction that every system, even empty space, contains a non-zero minimum amount of energy.  People have thought about tapping that energy to power perpetual motion machines.”

“That’d be cool — the ultimate renewable.”

“Wouldn’t it, though?  But no can do, for a couple of reasons.  Virtual particles, by their nature, are random phenomena.  You can’t depend upon what kind of particle might show up, or when, nor how long it might hang around.  It’s not like NFC where antennas generate the particles.  The other issue is that ‘minimum’ means minimum.  If you could pull energy out of that space you’d lower its energy content and drop it below the minimum…. What’s the grin about?”

“Just wondering how they’d score hitting a virtual ball that disappears before the fielder catches it.”

~~ Rich Olcott

Virtualosity

No knock, the door just opened suddenly.

“Hello, Jeremy.  Rule of Three?”

“Huh?  No, I was down the hall just now when I saw you go into your office so I knew you hadn’t gotten busy with something yet.  Sir.  What’s the Rule of Three?”

“Never mind.  You’re up here about virtual particles, I guess.”

“Yessir.  You said they’re ‘now you might see them, now you probably don’t.’  What’s that about and what do they have to do with abstraction and Einstein’s ‘underlying reality’?”

“What have you heard about Heisenberg’s Uncertainty Principle?”

“Ms Plenum says you can’t know where you are and how fast you’re going.”

“Ms Plenum’s got part of the usual notion but she’s missing the idea of simultaneous precision and a few other things.  Turns out you CAN know approximately where you are AND approximately how fast you’re going at a particular moment, but you can’t know both things precisely.  There’s going to be some imprecision in both measurements.  Think about Coach using a radar gun to track a thrown baseball.  How does radar work?”

“It bounces a light beam off of something and measures the light’s round-trip travel time.  I suppose it multiplies by the speed of light to convert time to distance.”

“Good.  Now how does it get the ball’s speed?”

“Uhh… probably uses two light pulses a certain time apart and calculates the speed as distance difference divided by time difference.”

“Got it in one.  Now, suppose that a second after the ball’s thrown the radar says the ball is 61 feet away from the plate and traveling at 92 mph.  Air resistance acts to slow the ball’s flight so that 92 is really an average.   Maybe it was going 92.1 mph at the first radar pulse and 91.9 mph at the second pulse.  So that reported speed has an 0.2 mph range of uncertainty.”

“Oh, and neither of the two pulses caught the ball at exactly 61 feet so that’s uncertain, too, right?”

“There you go.  We know the two averages, but each of them has a range.  The Uncertainty Principle says that the product of those two ranges has to be greater than Planck’s constant, 10-34 Joule·second.  Plugging that Joule-fraction and the mass of an electron into Einstein’s E=mc², we restate the constant as about 10-21 of an electron-second.  Those are both teeny numbers — but they’re not zero.”

“So speed and location make an uncertainty pair.  Are there others?”Zebras“A few.  The most important for this discussion is energy and time.”

“Wait a minute, those two can’t be linked that way.”

“Why not?”

“Well, because … umm … speed is change of location so those two go together, but energy isn’t change of time.  Time just … goes, and adding energy won’t make it go faster.”

“As a matter of fact, there are situations where adding energy makes time go slower, but that’s a couple of stories for another day.  What we’re talking about here is uncertainty ranges and how they combine.  Quantum theory says that if a given particle has a certain energy, give or take an energy range, and it retains that energy for a certain duration, give or take a time range, then the product of the two ranges has to be larger than that same Planck constant.   Think about a 1-meter cube of empty space out there somewhere.  Got it?

“Sure.”

“Suppose a particle appeared and then vanished somewhere in that cube sometime during a 1-second interval.  What’s the longest time that particle could have existed?”

“Easy — one second.”

“How about the shortest time?”

“Zero.  Wait, it’d be the smallest possible non-zero time, wouldn’t it?”

“Good catch.  So what’s the time uncertainty?”

“One second minus that tiniest bit of time.”

“And what’s the corresponding energy range?”

“That constant number that I forget.”

“10-21 electron-second’s worth.  Now let’s pick a shorter interval.  What’s the mass range for a particle that appears and disappears sometime during the 10-19 second it takes a photon to cross a hydrogen atom?”

“That’s 10-21 electron-second divided by 10-19 second, so it’d be, like, 0.01 electron.”

“How about 1% of that 10-19 second?”

“Wow — that’d be a whole electron.”

“A whole electron’s worth of uncertainty.  But is the electron really there?”

“Probably not, huh?”

“Like I said, ‘Now you probably don’t’.”

~~ Rich Olcott

Abstract Horses

It was a young man’s knock, eager and a bit less hesitant than his first visit.

“C’mon in, Jeremy, the door’s open.”

“Hi, Mr Moire, it’s me, Jerem…  How did ..?  Never mind.  Ready for my black hole questions?”

“I’ll do what I can, Jeremy, but mind you, even the cosmologists are still having a hard time understanding them.  What’s your first question?”

“I read where nothing can escape a black hole, not even light, but Hawking radiation does come out because of virtual particles and what’s that about?”

“That’s a very lumpy question.  Let’s unwrap it one layer at a time.  What’s a particle?”

“A little teeny bit of something that floats in the air and you don’t want to breathe it because it can give you cancer or something.”

“That, too, but we’re talking physics here.  The physics notion of a particle came from Newton.  He invented it on the way to his Law of Gravity and calculating the Moon’s orbit around the Earth.  He realized that he didn’t need to know what the Moon is made of or what color it is.  Same thing for the Earth — he didn’t need to account for the Earth’s temperature or the length of its day.  He didn’t even need to worry about whether either body was spherical.  His results showed he could make valid predictions by pretending that the Earth and the Moon were simply massive points floating in space.”

Accio abstractify!  So that’s what a physics particle is?”

“Yup, just something that has mass and location and maybe a velocity.  That’s all you need to know to do motion calculations, unless the distance between the objects is comparable to their sizes, or they’ve got an electrical charge, or they move near lightspeed, or they’re so small that quantum effects come into play.  All other properties are irrelevant.”

“So that’s why he said that the Moon was attracted to Earth like the apple that fell on his head was — in his mind they were both just particles.”

“You got it, except that apple probably didn’t exist.”

“Whatever.  But what about virtual particles?  Do they have anything to do with VR goggles and like that?”

“Very little.  The Laws of Physics are optional inside a computer-controlled ‘reality.’  Virtual people can fly, flow of virtual time is arbitrary, virtual electrical forces can be made weaker or stronger than virtual gravity, whatever the programmers decide will further the narrative.  But virtual particles are much stranger than that.”

“Aw, they can’t be stranger than Minecraft.  Have you seen those zombie and skeleton horses?”Horses

“Yeah, actually, I have.  My niece plays Minecraft.  But at least those horses hang around.  Virtual particles are now you might see them, now you probably don’t.  They’re part of why quantum mechanics gave Einstein the willies.”

“Quantum mechanics comes into it?  Cool!  But what was Einstein’s problem?  Didn’t he invent quantum theory in the first place?”

“Oh, he was definitely one of the early leaders, along with Bohr, Heisenberg, Schrödinger and that lot.  But he was uncomfortable with how the community interpreted Schrödinger’s wave equation.  His row with Bohr was particularly intense, and there’s reason to believe that Bohr never properly understood the point that Einstein was trying to make.”

“Sounds like me and my Dad.  So what was Einstein’s point?”

“Basically, it’s that the quantum equations are about particles in Newton’s sense.  They lead to extremely accurate predictions of experimental results, but there’s a lot of abstraction on the way to those concrete results.  In the same way that Newton reduced Earth and Moon to mathematical objects, physicists reduced electrons and atomic nuclei to mathematical objects.”

“So they leave out stuff like what the Earth and Moon are made of.  Kinda.”

“Exactly.  Bohr’s interpretation was that quantum equations are statistical, that they give averages and relative probabilities –”

“– Like Schrödinger’s cat being alive AND dead –”

“– right, and Einstein’s question was, ‘Averages of what?‘  He felt that quantum theory’s statistical waves summarize underlying goings-on like ocean waves summarize what water molecules do.  Maybe quantum theory’s underlying layer is more particles.”

“Are those the virtual particles?”

“We’re almost there, but I’ve got an appointment.  Bye.”

“Sure.  Uhh… bye.”

~~ Rich Olcott

Wikipedia Skillz

A young man’s knock, eager yet a bit hesitant.

“C’mon in, the door’s open.”

Tall kid, glasses, hoodie thrown back.

“Hi, Mr Moire, can I ask you some questions?  I’m doing a term paper on black holes and I’ve read up on in Wikipedia but there’s things I don’t understand and besides Ms Plenum said not to trust Wikipedia.”

“Hold on, son, let’s get acquainted first.  You are…?”

“My name’s Jeremy Brannigan, sir, and I’m like Richard Feynman’s archetypical intelligent high school student he wanted to explain things to except he gave up on particle spin.”

“Well, you have done your homework, though you’ve muddled a couple of his quotes.  But about Wikipedia — Ms Plenum’s mostly right but in my experience the technical articles are pretty dependable.  Those writers are usually more interested in explaining than convincing.  Have you checked Wikipedia’s Talk pages?”

“There’s, like, comments?”

“Sort of, except Talk pages lie behind articles and target what’s right or wrong and what should be changed to make the article better.  I often learn as much from the technical discussion as I do from the article itself.”

wikieyes

A riff on Wikipedia’s logo, original in Wikimedia Commons

“I’ve never seen those pages.  How do I get to them?”

“You need a desktop view.  That’s the standard view when you use a desktop or laptop computer, but you can only maybe get to it on a handheld device.  Depends on the device, the browser, and even their maintenance levels.  Do you have a handheld in that backpack?”

“Yeah, an iPad.”

“Safari, Firefox and Chrome can all show that other view.”

“I’ve got all three.”

“Great, pull up Chrome, get to Wikipedia and look up ‘Black hole.'”

… “Got it.  Uhh… don’t see anything about a Talk page.”

“You’re looking at ‘mobile mode.’  See that three-dots icon at the top right?  Tap on it and check the pop-up menu.”

“Hah, here’s one that says, Request Desktop Site.  I’ll tap on that.  Hey, now I’ve got tabs above the text, one says Article and another that says Talk.  Whoa, here’s one that says View Source.  Whups, now there’s a box that says I can start editing.  Better not, huh?  How do I get out of that?”

“Tap your browser’s backup button.  By the way, even though in principle anyone can edit any article, the Wikipedia moderators have locked down some of the most popular or controversial just to prevent update wars.  This article’s one of those.”

“Yeah, I just backed up then tried View Source again and it says I’m not an established registered user.  No duh, right?  OK, lessee what’s in the Talk page.  Umm, how-to stuff and then organization stuff and then, huh! ‘this article has been rated GA-class on the quality scale.’ People come around and, like, check your work?”

“Absolutely, which is why I think Ms Plenum’s advice is a little too pessimistic.  Trust but verify — if you see something you’d like to quote but you don’t want to look foolish, double-check with another source.  But on the whole I’ve found the science, math and other technical articles to be trustworthy.”

“Aha, the first set of comments is about my questions, Hawking radiation and how black holes evaporate and what are virtual particles and like that.”

“So many questions, so little time.  Let’s finish off with the browser issue before we dive into physics.  Bring up your Firefox browser on that iPad.”

“All right.  Mmm, I’m going to Wikipedia, and I’m searching for ‘Black hole’ … got it, but the display doesn’t have tabs or a three-dot icon.”

“Firefox has two ways to get to desktop mode.  One way is to tap the three-bar icon at the top right…”

“YESS! the pop-up menu has half-a-dozen options and there’s Request Desktop Site.  Hey, it toggles, I can flip modes back and forth.  Sweet!  What’s the other way?”

“Press-and-hold the reload circle-arrow in the address bar.”

“A-hah, that opens a Request Desktop Site button right under the arrow.  Cool, that’s a toggle, too.  How does Safari handle this stuff?”

“They use the reload circle-arrow ploy, same as Firefox, dunno who did it first.”

“Oops, late for class.  Seeya.”

“Don’t mention it.”

~~ Rich Olcott

Questions, Meta-questions and Answers

<We rejoin Sy and Vinnie in the library stacks…> “Are you boys discussing me?”

<unison> “Oh, hi, Ramona.”

“Actually no, Ramona, we were discussing relativistic time dilation.”

“I know that, Sy, I’ve been reading your posts. Now I’ve got a question.”

“But how…?  Never mind.  Guess I’d better watch my writing.  What can I do for you?”

“You and Vinnie have been going on about kinetic time dilation and gravitational time dilation like they’re two separate things, right?”

“That’s how we’ve treated them, right, but the textbooks do the same.  The velocity-dependent time-stretch equation, tslow/tfast = √[1-(v²/c²)], comes out of Einstein’s Special Theory of Relativity. The gravity-dependent equation, tslow/tfast = √[1-(2G·M/r·c²)], came from his General Theory of Relativity.”

“But there’s no rule that says an object can’t be moving rapidly while it’s in a gravitational field, is there?  That Endurance spacecraft orbiting the black hole in the Interstellar movie certainly seemed to be in that situation.”

“No question, Ramona.  General Relativity’s just more, er, general.”

“Fine, but shouldn’t they work together?”

That got Vinnie started.  “Yeah, Sy, I started this with LIGO and gravity but you and those space shuttles got me into this speed thing.  How do you bridge ’em?”

“Not easily.  Einstein set the rules of the game when he wrote down his fundamental equations.  Physicists and mathematicians have been trying to solve them ever since.  Schwarzchild found the first solution within a year after the equations hit the streets, but he did the simplest possible system — a non-rotating spherical object with no electrical charge and alone in the Universe.  It took another half-century before Kerr and friends figured out how to handle rotating spheres with an electric charge, but even those objects are assumed to be isolated from all other masses.  Mm … how do you figure velocity, Vinnie?”

“Distance divided by time, easy.”

“Not quite that easy.  The equations say that if you’re close to a massive object, space gets compressed, time gets stretched, and the time and space dimensions get scrambled.  Literally.  Time near a Schwarzchild object points inward as you approach the sphere’s center, and don’t ask me how to visualize that.  A Kerr object has a belt around its equator where time runs backwards.  Craziness.”

“Well, how about if I’m not that close?”

“That’s easier to answer, Ramona.  Suppose the three of us are each flying at safe distances from some heavy object with mass M.  I’m farthest away so I’m holding the fastest clock.  We’ll compare Vinnie’s and your clocks to mine.  OK?”3-clocks

“Sure, why not?”

“Fine.  Now, Vinnie, you’re closer in, resting on the direct line between me and the object.  You’re at distance r from it.  How fast does your clock run?”

“Uhhh…  We’re both on that same radial line so we’re in the same inertial frame, no kinetic effect.  I suppose you see it ticking slower because of the gravitational effect.”

“M-hm, and my clock ticks how often between ticks of yours?”

“You want the equation, huh?  All right, it’s tvinnie/tsy = √[1-(2G·M/r·c²)].”

“You’re reading my mind with those subscripts.  Now, Ramona, you’re at that same distance from the object but you’re in orbit around it.  Measured against Vinnie’s position you’ve got velocity v.  How fast is his clock ticking compared to yours?”

“Mmm…  We’re at the same level in the gravity field, so the gravitational thing makes no difference.  So … tramona/tvinnie = √[1-(v²/c²)].  Aaand, he’d see my clock running slow by the same amount. That’s weird.”

“Weird but true.  Last step — Ramona, you’re deeper in the gravitational field and you’re speeding away from me, so tramona/tsy=(tramona/tvinnie)*(tvinnie/tsy)=√[1-(2G·M/r·c²)]*√[1-(v²/c²)] covers both.”

“OK, that’s settled.  Back to Vinnie’s original question.  LIGOs are set in concrete, their velocities are zero so LIGO signals are all about gravity, right?”

“Right.”

Ramona links arms with him.  “Let’s go dancing.”  Then she gives me the eye.  “Sugarlumps, Sy?  Really?”

On the 12th floor of the Acme Building, high above the city, one man still tries to answer the Universe’s persistent questions — Sy Moire, Physics Eye.

~~ Rich Olcott

Weight And Wait, Two Aspects of Time

I was deep in the library stacks, hunting down a journal article so old it hadn’t been digitized yet.  As I rounded the corner of Aisle 5 Section 2, there he was, leaning against a post and holding a clipboard.

“Vinnie?  What are you doing here?”

“Waiting for you.  You weren’t in your office.”

“But how…?  Never mind.  What can I do for you?”

“It’s the time-dilation thing.  You said that there’s two kinds, a potential energy kind and a kinetic energy kind, but you only told me about the first one.”

“Hey, Ramona broke up that conversation, don’t blame me.  You got blank paper on that clipboard?”

“Sure.  Here.”

“Quick review — we said that potential energy only depends on where you are.  Suppose you and a clock are at some distance r away from a massive object like that Gargantua black hole, and my clock is way far away.  I see your clock ticking slower than mine.  The ratio of their ticking rates, tslow/tfast = √[1-(2G·M/r·c²)], only depends on the slow clock’s position.  Suppose you move even closer to the massive object.  That r-value gets smaller, the fraction inside the parentheses gets closer to 1, the square root gets smaller and I see your clock slow down even more.  Sound familiar?”

“Yeah, but what about the kinetic thing?”time-and-the-rovers

“I’m getting there.  You know Einstein’s famous EEinstein=m·c² equation.  See?  The formula contains neither a velocity nor a position.  That means EEinstein is the energy content of a particle that’s not moving and not under the influence of any gravitational or other force fields.  Under those conditions the object is isolated from the Universe and we call m its rest mass.  We good?”

“Yeah, yeah.”

“OK, remember the equation for gravitational potential energy?”

E=G·M·m/r.

“Let’s call that Egravity.  Now what’s the ratio between gravitational potential energy and the rest-mass energy?”

“Uh … Egravity/EEinstein = G·M·m/r·m·c² = G·M/r·c². Hey, that’s exactly half the fraction inside the square root up there. tslow/tfast = √[1-(2 Egravity/EEinstein)].  Cool.”

“Glad you like it.  Now, with that under our belts we’re ready for the kinetic thing.  What’s Newton’s equation for the kinetic energy of an object that has velocity v?”

E=½·m·v².

“I thought you’d know that.  Let’s call it Ekinetic.  Care to take a stab at the equation for kinetic time dilation?”

“As a guess, tslow/tfast = √[1-(2 Ekinetic/EEinstein)]. Hey, if I plug in the formulas for each of the energies, the halves and the mass cancel out and I get tslow/tfast = √[1-2(½m·v²/m·c²)] = √[1-(v²/c²)].  Is that it?”

“Close.  In Einstein’s math the kinetic energy expression is more complicated, but it leads to the same formula as yours.  If the velocity’s zero, the square root is 1.0 and there’s no time-slowing.  If the object’s moving at light-speed (v=c), the square root is zero and the slow clock is infinitely slow.  What’s interesting is that an object’s rest energy acts like a universal energy yardstick — both flavors of time-slowing are governed by how the current energy quantity compares to EEinstein.”

“Wait — kinetic energy depends on velocity, right, which means that it’ll look different from different inertial frames.  Does that mean that the kinetic time-slowing depends on the frames, too?”

“Sure it does.  Best case is if we’re both in the same frame, which means I see you in straight-line motion.  Each of us would get the same number if we measure the other’s velocity.  Plug that into the equation and each of us would see the same tslow for the other’s clock.  If we’re not doing uniform straight lines then we’re in different frames and our two dilation measurements won’t agree.”

“… Ramona doesn’t dance in straight lines, does she, Sy?”

“That reminds me of Einstein’s quote — ‘Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. That’s relativity.‘  You’re thinking curves now, eh?”

“Are you boys discussing me?”

<unison> “Oh, hi, Ramona.”

~~ 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