NEIL DeGRASSE TYSON (Astrophysicist/AmericanMuseum of Natural History): On this episode of NOVA scienceNOW: Everybody knows earthquakeshappen in places like California, but there may be a looming threat where you least expectit.
Memphis, Tennessee? That's right; land ofElvis, barbecue, and Beale Street.
These folks don't look too worried, but maybethey should be.
Some of the most powerful earthquakes in history happened right undertheir feet.
Now, geologists are deep underground, uncoveringa frightening pattern.
BRUCE FOULKE (University of Illinois at Urbana-Champaign):And that layered stalagmite is what lets us recreate the timing of earthquakes.
NEIL DeGRASSE TYSON: Could the next big onestrike America's heartland? Also, why are these fruit flies being rolledand bumped on a machine called the deprivator? It's all in the name of sleep research.
MATTHEW WILSON (Massachusetts Institute ofTechnology): Sleep is an enigma.
What is its purpose? That's something that we do not understand.
NEIL DeGRASSE TYSON: But new studies indicatethat one purpose of sleep may be to help us learn, that while we snooze, our brains replaymemories, maybe even editing and enhancing them.
ROBERT STICKGOLD (Beth Israel Deaconess MedicalCenter): When we wake up in the morning, in some way, we have a different brain.
NEIL DeGRASSE TYSON: And in our profile, you'llmeet "the Stephen Hawking of South Korea.
" SANG-MOOK LEE (Seoul National University):He looks into the universe; I look into the bottom of the sea.
NEIL DeGRASSE TYSON: A geophysicist and professor,struck down in his prime.
SANG-MOOK LEE: My van flipped, I was crushed.
NEIL DeGRASSE TYSON: He struggled for acceptancein a society that shuns the disabled.
SANG-MOOK LEE: People with disabilities tendto hide in a shadow.
NEIL DeGRASSE TYSON: Fueled by his passionfor science, he fought his way back, inspiring others to overcome their disabilities.
SANG-MOOK LEE: I ask myself, "What can I do,actively, to give back?" NEIL DeGRASSE TYSON: All that and more onthis episode of NOVA scienceNOW.
SLEEPNEIL DeGRASSE TYSON: Hello.
I'm Neil deGrasse Tyson, your host for NOVA scienceNOW.
We all know that dreams can be, dreams canbe a little weird, sometimes filled with bizarre events that would never happen in real life.
Nobody really knows why we dream.
In fact, nobody really knows why we sleep.
Here are some folks who are trying to figureit out.
Amita Sehgal likes her flies, fruit flies,to be precise.
AMITA SEHGAL (University of Pennsylvania andHoward Hughes Medical Institute): I do have a genuine affection for them.
NEIL DeGRASSE TYSON: But sometimes, she hasa strange way of showing that affectionóespecially, when she puts them into this thing.
AMITA SEHGAL: We use this piece of equipmentwe call "The Deprivator.
" NEIL DeGRASSE TYSON: The Deprivator? It'slike riding a roller coaster during an earthquake.
What's interesting to Sehgal is what the fliesdo after spending a whole night in here.
The flies on the left were undisturbed last night,and they look fine.
But the flies on the right, they were jostled all night long in the Deprivator.
Now, some of them look dead, but they're not.
According to Sehgal, they're catching up onlost sleep.
AMITA SEHGAL: If we keep flies awake at night,they need to make up for the sleep they have lost, and so will sleep in the morning, ata time when they're normally active.
NEIL DeGRASSE TYSON: But why would flies needto sleep? Could it be for the same reason we need to sleep? Maybe.
But if you ask anexpert what exactly that reason is.
MATTHEW P.
WALKER (Harvard Medical School):We actually know very little about what sleep is doing for the brain.
AMITA SEHGAL: We spend a third of our livessleeping.
If you don't sleep, you die.
MATT WILSON: Sleep is an enigma.
What is itspurpose? That's something that we do not understand.
NEIL DeGRASSE TYSON: Looks like a waste oftime.
But then why would so many creatures do it? MATT WILSON: Sleep is something that, themore we look at it, the more we see that it is fundamental.
It's fundamental to essentiallyall organisms.
NEIL DeGRASSE TYSON: Including, it seems,organisms like fruit flies.
When they're not being knocked around all night, Amita Sehgal'sflies follow a pretty familiar schedule.
AMITA SEHGAL: They're active during the dayand they sleep at night, for the most part, although there is an afternoon siesta as well,especially in males.
NEIL DeGRASSE TYSON: Trying to pinpoint thereason for a fly to snooze up to 12 hours a night, Sehgal's lab studies the fruit fly'sbrain.
AMITA SEHGAL: What we were doing was tryingto figure out which part of the fly brain was important for sleep.
NEIL DeGRASSE TYSON: Sehgal's experimentspointed to the mushroom body, a part of the brain found in creatures like insects andspiders, but not in humans.
Biologists have known about the mushroom body for years, butthey associated it, not with sleep, but with something else entirely, an insect's memory.
AMITA SEHGAL: There is, then, this structurein the fly brain, which we already knew was required for memory, and we now find thatit controls sleep.
NEIL DeGRASSE TYSON: The finding's intriguingbecause, for a long time now, sleep researchers have been debating a possible connection betweensleep and memory.
Bob Stickgold has been looking into this possibility,sometimes in unconventional ways.
For him, video games are research tools that can helpreveal how our brains learn.
ROBERT STICKGOLD: Do you remember, when youfirst started playing TetrisÆ,.
NEIL DeGRASSE TYSON: Oh, yeah.
ROBERT STICKGOLD:.
That you went to bedat night, and you lay in bed, and you closed your eyes, and you saw little Tetris piecesfloating around in front of your eyes? NEIL DeGRASSE TYSON: How did you know that?How did you know that.
ROBERT STICKGOLD: Because.
NEIL DeGRASSE TYSON:.
I dreamed Tetris shapes? ROBERT STICKGOLD:.
Because everybody does.
NEIL DeGRASSE TYSON: After taking a few rideson a ski machine, Stickgold's research subjects fall asleep, and then he promptly wakes themup.
ROBERT STICKGOLD: If we wake you up just twoor three minutes after you fall asleep and ask you, "Neil, what's going through yourmind?" You'll say, "Seeing those suckers somersaulting down when I crash.
" NEIL DeGRASSE TYSON: And why would I dreamof this embarrassing moment? Stickgold is convinced that while you sleep,your brain is reviewing what you've learned and strengthening your memories.
ROBERT STICKGOLD: The brain is being modifiedwhile we sleep, so that when we wake up in the morning, in some way, we have a differentbrain.
And it's a brain that functions better.
NEIL DeGRASSE TYSON: At least it seems tofunction better on some kinds of memory tasks.
Recent studies show that after a single night'ssleep, sometimes even after a nap, we can do a better job recognizing visual patternsand even solving some math puzzles.
MATTHEW WALKER: What we're going to have youdo is try and type out a short, five-digit sequence.
NEIL DeGRASSE TYSON: I saw it first-hand whenI took a simple typing test, typing a string of five numbers over and over again, as fastas I could.
After a night's sleep, I could suddenly typethe numbers faster and more accurately.
And research backs this up.
Most people improvedtheir typing by about 20 percent after sleep.
MATTHEW WALKER: Practice doesn't make perfect.
It seems to be practice with a night of sleep that makes perfect.
Sleep is enhancing thatmemory so that when you come back the next day you're even better than where you werethe day before.
NEIL DeGRASSE TYSON: But exactly how couldsleep enhance your memory? We don't know.
But possible clues have been showing up, notjust in the brains of flies, but in the dreams of rats.
M.
I.
T.
researcher Matt Wilson says he canread rats' minds, including their dreams, with tiny electric probes.
MATT WILSON: What it means is that we're ableto, at any time, plug in our electronics, and.
NEIL DeGRASSE TYSON: Figure out what they'rethinking.
MATT WILSON:.
Read their, read their mind.
NEIL DeGRASSE TYSON: Wilson's mind-readersare actually thin wires, about a tenth the width of a human hair, that pick up the electricalsignals among dozens of brain cells.
The wiresópainlessly implanted in the rat'sbrain and held there by a kind of hatócarry the signals right into Wilson's computers.
That information comes up back through theseconnectors into your computer, and you're sitting there watching a map of the thoughtsof this rat? MATT WILSON: Exactly.
That's exactly right.
NEIL DeGRASSE TYSON: It's remarkable.
Wilson is most interested in mapping the rat'sthoughts in a part of the brain called the hippocampus.
Like the fruit fly's mushroombody, the hippocampus of a rat or a human plays an important role in memory, includingour sense of space and location.
Wilson uses a specially designed rat maze.
If the rat follows the right route, he's rewarded with some chocolate syrup.
And as he movesthrough each different spot in the maze in search of his goal, a unique pattern of cellsfires in his brain.
MATT WILSON: So we can tell where the animalis, simply based upon which cells in the hippocampus are active.
That pattern will be unique fora given location in a given environment.
NEIL DeGRASSE TYSON: What's amazing is thatthe same patterns turn up again, even after the rat drifts off to sleep.
That's right, Wilson eavesdrops on the rats'dreams.
And they aren't about cheese, they're about running the maze.
MATT WILSON: So when the animals would goto sleep, we would see these patterns of brain activity that were expressed while the animalswere running on the maze, being replayed, in the same sequence, the same order in whichthey had been experienced.
NEIL DeGRASSE TYSON: But the replay wasn'texactly the same as when the rat ran the maze.
Sometimes it was like an extreme fast-forward;quick flashes of the experience.
MATT WILSON: Now, at the time, you never knowwhat is going to be important and what is not important.
So you may re-evaluate or editthose memories to identify the things that were important.
NEIL DeGRASSE TYSON: And this fragmented replaywasn't just happening in the hippocampus.
Wilson also detected it in the visual cortex,meaning the rats were likely seeing the maze in their sleep.
What's more, the visual cortex is part ofthe larger neocortex, which, in humans, is responsible for, among other things, long-termmemory.
MATTHEW WALKER: The hippocampus is replayingthe events of the day.
The hippocampus is almost, sort of, reactivating the memoriesat night and playing them out to the neocortex.
It's almost as though the hippocampus is havinga therapy session with the, with the neocortex.
And it's almost saying, "Okay, here's whatwe learned during the day.
" MATT WILSON: What are rats and what are peopledoing during sleep? They are processing memory.
They are replaying memory.
Now, we could ask,"Is this about learning?" And I believe that's exactly what it is about, that animals are,and humans, are trying to learn from past experience.
NEIL DeGRASSE TYSON: So, the idea here isthat the sleeping brain might be reviewing and strengthening new memories it wants tohold onto for the long-term.
And it might identify certain goals we want to work towards.
So could it be that "sleeping on it" isn'tjust an old saying, but a biological process that consolidates and organizes importantinformation? MATT WILSON: These are pretty big concepts.
And they certainly are controversial.
The function of sleep, as it relates to learningand memory, that's something that, at this point, remains speculation.
We're making aleap.
NEIL DeGRASSE TYSON: Not everybody is leapinginto bed with this idea.
And researchers have a long way to go before they know what sleepis really doing for our brains.
But if the speculation turns out to be true, then you'dhave to wonder, "What is our 24/7 culture doing to our ability to think straight?" MATTHEW WALKER: Sleep is not just somethingthat we can choose to sort of dabble in every now and again.
It's not a luxury; it's a biologicalnecessity.
MATT WILSON: My sense is that disruption ofsleep is much deeper than simply, you know, robbing us of rest.
My guess would be thatwe lose the opportunity to gain understanding, a deep understanding of our past experience,that what we sacrifice, in a sense, is wisdom.
FIRST PRIMATESNEIL DeGRASSE TYSON: As inhabitants of Earth, we humans are relative newbies.
In fact, ourbranch of the evolutionary tree may have split with these apes only about 6,000,000 yearsago.
But what if we look further back in our primatefamily tree? There must have been some great and wise ancestor who founded this wonderfulline of creatures, right? Well, as correspondent Peter Standring reports, the latest researchis revealing that our origins may have been quite a bit humbler than we thought.
PETER STANDRING (Correspondent): The Badlandsof Wyoming: some of the largest dinosaur bones, ever, were found right here.
But Universityof Florida paleontologist Jonathan Bloch is hunting for a set of bones that are nothinglike the giant bones of T-Rex.
JONATHAN BLOCH: Here's a little piece of bonehere.
Here's a little piece of bone.
I think that's a little vertebra.
PETER STANDRING: Tiny mouse-sized bones, buriedin limestone, that just might be the fossil remains of our earliest primate ancestors.
An age-old mystery surrounds the origin ofprimates.
No one knows exactly where we come from or how we got our evolutionary start.
Here's what we do know: giant dinosaurs onceruled this basin, where they dined freely in a lush forest.
But then, around 65 millionyears ago, the dinosaurs die off when a massive comet slams into the planet.
Ten million yearslater, something extraordinary happens.
The fossil record suddenly shows a new kind ofmammal, with unique characteristics: the primate, our ancient ancestors.
So what is a primate? What is it that separatesus from the rest of the evolutionary pack? Well, maybe it's our good looks or our superiorintelligence.
The truth is brain size does come into play.
We primates, even Noah here, have larger brains than our mammal relatives.
It's a featurethat evolved to help us learn complex social behavior and how to do things like make toolsor even outwit our prey.
We also developed forward-facing eyes withstereo vision.
It's a feature that allows us to judge the world around us in 3D.
Overtime, we also developed the ability to leap, basically to jump from branch to branch, wheregrasping hands, or in Noah's case, grasping feet, equipped with nails instead of claws,enable us to reach that tasty piece of fruit.
Our earliest ancestors developed these uniquecharacteristics, some time after the extinction of dinosaurs.
The question is, "When and why?" So let me get it straight.
If the dinosaursbecame extinct 65 million years ago, and then primates suddenly appeared around 56 millionyears ago, what happened in between? I mean that's almost 10 million years that's unaccountedfor.
JONATHAN BLOCH: Right.
That's the $6,000,000question.
And I don't think they just appeared on the face of the planet, they evolved.
PETER STANDRING: But from what? I mean, somethingthe size of a mouse? JONATHAN BLOCH: Exactly.
PETER STANDRING: Jonathan believes the evidenceto support his theory and help solve this ancient primate mystery can be found here,hidden inside the limestone of the Bighorn Basin.
JONATHAN BLOCH: A tiny little piece of brokenbone can connect up with an entire skeleton of a mammal.
This looks like a pretty good limestone.
Itshould be.
Should be full of fossils, but we really won't know until we get it backto the lab.
You see a tiny little piece of bone, and youhope that there's more inside, you have no guarantees, so it's a little bit of a gamble.
PETER STANDRING: But a gamble worth taking,because these stones might hold ancient clues.
Back in his lab, Jonathan, along with graduatestudent Doug Boyer, gets to work.
Their goal? To free the delicate bones from the rock-hardstone.
They begin by placing the limestone under a microscope.
JONATHAN BLOCH: That immediately starts toopen up the world of the block.
We identify all of the bone that's outcropping on thesurface.
PETER STANDRING: Doug carefully coats thetiny bones with plastic to protect them from the powerful acid bath they're about to take.
DOUG BOYER (Stony Brook University): We leavethe block in acid for, at the most, two to two and a half hours, and that'll remove abouta millimeter-thick rind of limestone.
JONATHAN BLOCH: We repeat the process, againand again and again and again, until all of the bone is exposed.
PETER STANDRING: Much to their surprise theyfind hundreds of tiny bones.
Doug devises a method to meticulously documentthe relationship between each and every bone.
The process will take months, but when complete,it will reveal far more than they ever anticipated: dozens of tiny mammals never before seen,including these three extraordinary skeletons.
And what are these? JONATHAN BLOCH: These are plesiadapiforms.
PETER STANDRING: Plesiadapiforms are tinymouse-like creatures that lived during the mysterious 10-million-year period betweenthe extinction of dinosaurs and the appearance of primates.
It's a very diverse group, withmore than 120 species, including these three.
JONATHAN BLOCH: They represent the most completeskeletons of plesiadapiforms known in the world.
PETER STANDRING: An extraordinary find, forsure, but will they help Jonathan solve this primate mystery? Are plesiadapiforms our earliestancestors? JONATHAN BLOCH: If we look here, this nail-likestructure makes you think, because the presence of a nail is a hallmark characteristic ofliving primates.
PETER STANDRING: This is an enlarged imageof the extraordinary nail Jonathan found.
Next to it, the claw he expectedóa startlingdifference.
JONATHAN BLOCH: This nail might actually bethe first nail in the history of primate evolution.
PETER STANDRING: Concrete evidence to supporthis theory of primate evolution.
Could there be more hidden within these tiny bones? To find out, Jonathan enlists the help ofMary Silcox, evolutionary anthropologist at the University of Winnipeg.
She's been busyzapping primitive skulls with an industrial-strength CAT scanner, large enough to fill an entireroom.
Mary takes the skull of one of the limestone skeletons and prepares it for scanning.
MARY T.
SILCOX (University of Winnipeg): Thex-ray goes through the specimen, and we collect 2,400 separate views, which produce a cross-sectionalimage.
A structure that had been identified as justa little piece of bone in the middle ear actually had the form of a tube.
And the reason thatwas exciting was because there's a structure running through the ear of particularly primitiveprimatesóthings like lemursówhich is a tube for a large vessel that goes to the brain.
PETER STANDRING: A tiny tube, a tiny nail,the evidence is mounting.
But to prove his theory of primate evolution, Jonathan stillneeds more.
He adds another member to the team.
Eric Sargis, professor of anthropologyat Yale University, and the world's leading expert on tree shrews.
Why a tree shrew expert?Scientists believe that tree shrewsóa primitive species of tiny tree-living mammalsóare actuallyrelated to early primates.
ERIC SARGIS: Tree shrews are not primates,but they're close relatives.
They share a number of characteristics that separates themfrom other groups of mammals.
PETER STANDRING: Would plesiadapiforms passthe ultimate primate test? Are they the first step on the primate family tree or just anotherrelative on the tree shrew family tree? The team goes to work bringing together allthe information they had collected independently into a single comprehensive study.
Detail by detail, feature by feature theycomb through all the data using a numerical system to compare and contrast.
JONATHAN BLOCH: After we studied the differentcharacteristics of these animals, and reduced them down to numbersóyou know, absence ofa nail is a 0, presence of a nail is a 1ówe then ran this through a computer algorithm.
PETER STANDRING: Using this information, thecomputer was programmed to create family trees illustrating the potential relationships eachmammal has to the next.
The team expected the computer to come up with several possiblescenarios in the form of several possible family trees.
Instead, the program came upwith only one.
JONATHAN BLOCH: I was a little surprised tosee it so unambiguous.
PETER STANDRING: This single family tree couldlead to only one conclusion.
JONATHAN BLOCH: I think the evidence, as itstands today, is pretty compelling that yes, in fact, these are primates.
MARY SILCOX: Every new piece of data thatwe had coming out of our study of this material seemed to be consistent with that idea.
PETER STANDRING: Not only that.
One of theplesiadapiform skeletons Jonathan and Doug painstakingly etched out of limestone, a speciesby the name of Dryomomys, turns out to be far more primitive than the other two, possessingonly one primate characteristic, the shape of its teeth.
ERIC SARGIS: It's sort of a transitional specimenbetween more primitive things, like tree shrews, and later primates.
PETER STANDRING: One part primate, other partsnot.
ERIC SARGIS: I mean, it really starts to tellus something about the base of the primate tree, what the earliest primates look like.
So, if we're one leaf on the branch, so are chimpanzees, gorillas, orangutans, among apes;all the different monkeys in the old world and the new world; lemurs from Madagascar;lorises and galagoes; all those animals are living today, but you can trace it all backto a single common ancestor.
And as you get closer and closer to that common ancestor,dryomomys is one of the animals that's closest to the base there.
It's the most primitiveprimate skeleton ever found, to date.
PETER STANDRING: Jonathan had evidence tosupport his theory.
Primates didn't just appear on the planet, they evolved over a 10-million-yearperiod.
And just as he thought, the earliest primates were the size of a mouse.
Still onequestion remains.
What sparked this amazing transformation? The team believes our ancientancestors evolve on the heels of a mass extinction.
Without the mighty T-Rex around, the tiniestof mammals are free to forage and explore, and they discover a world filled with floweringplants and succulent fruit.
With tempting fruit growing at the end oftiny branches, our ancestors have plenty of motivation to change.
So they begin to evolve,developing long fingers for climbing trees, specialized teeth, hands and feet, uniquelydesigned for grasping and eating the tiniest, tasty berry.
Over 10 million years, they slowlydevelop unique characteristics that we recognize in our primate relatives and ourselves.
ERIC SARGIS: So that if plesiadapiforms don'tevolve, we're probably not standing here talking about this right now.
EARTHQUAKES IN THE MIDWESTNEIL DeGRASSE TYSON: We've got a pretty good idea of what causes earthquakes in placeslike California.
It's all about movement along the big cracks in Earth's crust.
North Americais part of a giant rigid plate of crust moving this way, and the Pacific Ocean sits on anotherplate moving this way.
Most of the time, the edges are just kind of stuck together, butevery now and then, the tension gets too high.
Boom! The edges slip; you get an earthquake.
So you might think, "Hey, if I just stay awayfrom here, I can avoid the big shake up.
" But not so fast.
As correspondent Peter Strandringreports, they're now realizing that there's another kind of quake.
It's big, it's dangerous,and it could be headed straight for the middle of America.
PETER STANDRING: Sam Panno is on the hunt.
He's looking for evidence, hidden deep inside a cave in Illinois.
There's over 14 milesof wet, slippery, bat-filled tunnels down here.
After hours of hiking, he spots what he'scome for.
SAM PANNO (Geochemist, Illinois State GeologicalSurvey): Looks good.
PETER STANDRING: These lumps of rock mightnot look like much, but for Sam, they could help answer a frightening question: "Is theAmerican heartland about to be hit with a cataclysmic earthquake?" When I think earthquake, I think California,the San Andreas Fault and fears of "the big one.
" And that makes sense, because most bigearthquakes happen in places like California, where big plates of the earth's crust collidewith each other.
But if you ask the experts, they'll say one of the biggest looming earthquakethreats in the US is far from California.
In fact, it's here, in Memphis, Tennessee.
It's Saturday night, and the crowds on BealeStreet seem pretty, well, carefree.
But about 200 years ago, the entire region was rockedby enormous earthquakes, and experts like Gary Patterson say Memphis has something toworry about.
So here we are on Beale Street on a Saturdaynight, and, obviously, the place is packed.
From what I understand, luckily, Memphis didn'texist when the big quakes were happening in 1811 and 1812.
GARY PATTERSON (University of Memphis): That'sright.
We didn't have instruments in the ground, but we know they were really big.
They reallyhappened and they could really happen again.
What happened was that the midwest was hitby not one, but three epic earthquakes, with epicenters somewhere near the town of NewMadrid, Missouri.
According to eyewitnesses, parts of the MississippiRiver changed direction.
TISH TUTTLE (U.
S.
Geological Survey): Geysersof water and sand went shooting into the air.
Fissures were forming in the ground.
Someof them were so large that they were afraid they'd be swallowed up by them.
PETER STANDRING: In fact, one report claimedeight Indians were killed by the opening and shutting of the earth.
There weren't any big cities in the region,and no one knows how many people died, but the tremors were so strong, they were feltfrom Mexico to Canada, over a thousand miles away.
How is it possible that some of the biggestquakes in American history would strike in the middle of the continent, where there areno visible faults, and away from the plate boundaries? GARY PATTERSON: It's an enigma.
It's, it's,it's a, it's a puzzle.
PETER STANDRING: To help solve the mystery,geologists are trying to uncover the truth of what happened here in the past.
And that'swhy I joined geologist Sam Panno and his team on their little cave adventure, to track downrocks that bear the imprint of ancient earthquakes.
And I expect we're going to get muddy? SAM PANNO: A little bit.
PETER STANDRING: If we want to find the rightrocks, it turns out we need to go underground, and we need to get a little wet.
Hey, Sam, I guess that trail of popcorn thatI dropped behind us isn't going to do us any good at this stage.
SAM PANNO: I guess not.
PETER STANDRING: Lucky for me, Sam knows hisway around these tunnels, all 14 miles worth.
He's been trekking through midwestern cavesfor years, on the hunt for stalagmites, those spikes of rock that grow up from the cavefloors.
Since they build up gradually, from mineralsdripping from above, each stalagmite carries a unique geological record, sometimes stretchingback tens of thousands of years.
If earthquakes happened here, the stalagmiteswill prove it.
SAM PANNO: Stalagmites grow layer upon layer.
PETER STANDRING: Break a stalagmite in half,and you can see rings of growth, kind of like tree rings.
SAM PANNO: You have the youngest rings onthe outside, the oldest ring on the inside.
PETER STANDRING: So a stalagmite like thisone, for example, may have taken tens of thousands of years to grow to that height? SAM PANNO: That's about right.
PETER STANDRING: For years, Sam has been takingsamples of these rocks to hunt for signs of earthquakes hidden in their crystal rings.
Back in the comfort of a warm, dry lab, thecollection starts to tell a story.
BRUCE FOULKE: That one layer would have beena split.
PETER STANDRING: Bruce Foulke, at the Universityof Illinois, studies the rocks Sam gathers.
Even the rough shape can reveal past earthquakes.
BRUCE FOULKE: You can see that the outermostlayer here is shifted.
Instead of growing here, it's moved down and shifted off to here.
The reason that's happened is the stalagmite is growing from a point source of water that'sdripping, dripping, dripping.
Then we had earthquake activity, and the position of thedrip moved.
And now the new drip started accumulatingand growing a new stalagmite in this position, which is down and off the shoulder of theold stalagmite.
PETER STANDRING: Whenever they spot a shiftlike this, the team cuts a paper thin slice of stalagmite.
With a powerful microscope,Bruce can isolate individual crystal layers.
BRUCE FOULKE: Wow.
PETER STANDRING:.
And see exactly wherethe earthquake happened.
BRUCE FOULKE: That specific line is representedhere on the microscope screen by this dark area of crystal growth.
PETER STANDRING: To date the earthquake, theydon't count the rings like you do with tree rings.
Instead, high precision chemical analysisof the crystals reveals how long ago they formed.
When the results for this stalagmite cameback, the team discovered that this major shakeup dates to about 200 years ago, a remnantof the great quakes of 1811 and 1812.
And with other samples they've gathered, theteam has uncovered more.
In fact, the rocks reveal a pattern of violentmidwestern earthquakes stretching back at least 15,000 years.
The 1811, 1812 quakesweren't a freak one-time event.
And if they happened many times before, then they willprobably happen again.
The big question is when.
Today, the whole region, called the New MadridSeismic Zone, is carefully monitored by seismic sensors.
It turns out the ground here is shakingalmost every day.
GARY PATTERSON: We have about 200 small earthquakesper year, 90 percent of those too small to be felt by humans.
It's the most active seismiczone east of the Rockies.
PETER STANDRING: So why is the midwest madeof such shaky ground when there are no visible faults on the surface? According to one theory, it's because theregion lies over an ancient wound, deep down in the earth's crust.
GARY PATTERSON: Half a billion years ago,the North American continent was being pulled apart by plate tectonic forces.
And it createda rift.
PETER STANDRING: But at some point, the continentstopped breaking up.
GARY PATTERSON: For some reason, that riftfailed.
PETER STANDRING: The failed rift created aweak spot in the crust, which might make the region more vulnerable to quakes, but no onereally understands how.
To try to get a better picture of what mightbe going on, Beatrice Magnani is probing the earth's crust beneath the Mississippi River.
Chugging along in a tugboat, her team sendspowerful sound waves down through the water, and a mile deep into the earth's crust.
Asthe sound waves bounce back, they're picked up by dozens of small microphones trailedby 80 yards of cable in the river.
The echoes reveal distinct layers of sediment.
BEATRICE MAGNANI (University of Memphis):Reading the sediments is like reading a book.
The sediments tell us the story of what happenedwith time.
PETER STANDRING: What happened was these layersbecame deformed and folded by major earthquakes.
But as Magnani discovered, these folds wereoutside the currently active New Madrid Seismic Zone.
BEATRICE MAGNANI: Nobody knew about thesefaults.
It's actually a discovery that.
It's even more puzzling than not finding anything.
PETER STANDRING: For Magnani, it means thatover the eons, the danger zone in the midwest may jump from one area to another, which makesit even more difficult to predict future big earthquakes in an area that is underprepared.
This city wasn't even founded until sevenyears after the great earthquakes of 1811 and 1812, so it's hard to imagine what wouldhappen if something of the same magnitude occurred in this region today.
If the 1811 and 1812 quakes are repeated,they will affect much more than Memphis, but also the entire region stretching to the north,including St.
Louis.
GARY PATTERSON: A huge area would be affected,possibly an area containing 12 million people.
There're a lot of old buildings.
PETER STANDRING: Whenever it happens, thenext big midwestern earthquake is guaranteed to be catastrophic, destroying billions ofdollars in property, and affecting millions of lives.
Yet, unlike Californians, many people hereremain unaware that their cities and towns stand on potentially very shaky ground.
PROFILE: SANG-MOOK LEENEIL DeGRASSE TYSON: Scientific research is filled with challenges like will your experimentwork or won't it? People can invest years of their lives, not knowing if they'll getthe payoff of a big discovery.
In this episode's profile, we meet a man whomet all the ordinary challenges to become a successful researcher, and then one day,quite suddenly, was handed a whole new set of overwhelming obstacles that his passionfor science empowered him to overcome.
Meet Sang-Mook Lee.
Where he's from, he'sknown as the "Stephen Hawking of South Korea.
" SANG-MOOK LEE: "Sang-Mook Lee, professor ofSeoul National University, also known as Stephen Hawking of Korea.
" That's like a fixed quote.
Every time I'm cited, they cite like that.
He looks into the universe; I look into thebottom of the sea.
NEIL DeGRASSE TYSON: Sang-Mook is an esteemedprofessor at South Korea's top university, and one of the foremost geophysicists in hiscountry.
He studies underwater volcanoes and tectonic plates deep beneath the ocean.
Yet, just three years ago, he was in a near-fatalcar accident that left him paralyzed from the neck down.
Many thought he would neverwork again.
MIKE GURNIS (California Institute of Technology):He was heavily sedated; he couldn't move; the machines were keeping his lungs going,but you could just see a light in his eye and that there was a future out there.
NEIL DeGRASSE TYSON: He made an impossiblecomeback.
He has since emerged as a national hero.
KUNWOO LEE (Seoul National University): Byshowing his attitude, will become a hope for every handicapped people.
NEIL DeGRASSE TYSON: He credits his returnto his passion for science.
SANG-MOOK LEE: I just love science.
I knewI had to get back because it was something I really wanted to do.
NEIL DeGRASSE TYSON: Sang-Mook's love forscience began as a child, when he dreamt of exploring the world.
SANG-MOOK LEE: That's when I dreamt aboutbeing a globetrotter and going around the world at very exotic places.
NEIL DeGRASSE TYSON: He went after this dream.
Getting a Ph.
D.
in geophysics from M.
I.
T.
, he began a life on the sea.
SANG-MOOK LEE: When I returned back to Korea,I became the marine geophysicist in Korea, and we had the ship.
That was when my sciencegot really, really exciting, because I was the only one in charge of this big ship.
You'rebeing like pirate.
NEIL DeGRASSE TYSON: His research involvesstudying the submarine activity of tectonic plates, those massive slabs of rock that makeup Earth's crust.
SANG-MOOK LEE: We use indirect ways to imagewhat is below the seafloor, because all the records are preserved in the ocean.
NEIL DeGRASSE TYSON: Shooting seismic wavesthrough the ocean floor creates a picture of what lies inside the earth.
These picturesallow him to monitor underwater earthquakes and volcanoes, and learn more about how Earth'scrust was formed.
SANG-MOOK LEE: What I do is I study the past200-million years of Earth's history, to understand how Earth has behaved in the past four anda half billion years.
NEIL DeGRASSE TYSON: Sang-Mook hopes thatby studying the tectonic activity in uncharted regions, we might someday be able to forecastgeological disasters, like tsunamis and earthquakes.
SANG-MOOK LEE: I looked at the map of thewestern Pacific, and I tried to choose targets where nobody has gone before.
I think thatis the real essence of science, discovery, like, climbing up the peak of a mountain thatnobody has gone before.
NEIL DeGRASSE TYSON: But everything changedon July 2, 2006, on a field trip to California, with a group of students.
SANG-MOOK LEE: It was toward the end of ourtrip, and we were working toward Death Valley.
I don't remember anything, that day, nothingat all.
People will tell me, "This is what happened.
This is what happened.
" "Oh, is that so?" I don't recall anything.
My van flipped, and I was crushed in the seat.
NEIL DeGRASSE TYSON: Sang-Mook's fourth cervicalvertebrae had been fractured, and he was in a coma.
SANG-MOOK LEE: When I was still in coma, Iknew that I was injured.
And I said, "Oh, Sang-Mook, you're in trouble.
" And then, Isaid, "But Sang-Mook, you have been in difficult situations before, so you can come out ofthis trap.
Figure out what to do.
" NEIL DeGRASSE TYSON: He awoke from his comaafter three days, paralyzed from the neck down.
SANG-MOOK LEE: Immediately after the injury,I worried that I wouldn't be able to work.
NEIL DeGRASSE TYSON: And he worried aboutthe challenges that South Koreans with disabilities commonly face, challenges like economic hardshipand family problems.
Married with three children, Sang-Mook Lee and his family would ultimatelyseparate, and although financially able to provide for his own care, he knew he wouldhave to contend with the stigma that so often accompanies disability, especially in SouthKorea.
DAN SHIM (Massachusetts Institute of Technology):People with disabilities are not well accepted in this society.
And they tend to hide ina shadow and, you know, they don't want to expose themselves.
Even taxi drivers willrefuse to, to get you on, if you have disability.
SANG-MOOK LEE: In Korea, people with my levelof injury would stay in the hospital, or would shun from the society, but I was not embarrassedto come back to my work and to try to do what I used to do.
NEIL DeGRASSE TYSON: Using all the technologiesavailable, he was out of bed within a month of his accident.
SANG-MOOK LEE: Science played a very, veryimportant part for me to come back after the injury.
Because of my interest in science,I just thought, "I must go back to work.
" MIKE GURNIS: Suddenlyóand it was, it seemedlike it was suddenlyónow he was in motion again.
He had this chair, and he had all ofthe gizmos.
And he could literally move the wheelchair around, turn it, and then alsouse computer devices, almost immediately, by breathing into a straw.
He also could movehis head back and press a button by moving his head.
I mean it was extraordinary to seethis happen so quickly.
NEIL DeGRASSE TYSON: Just six months later,Sang-Mook returned to teaching.
SANG-MOOK LEE: One day, a reporter noticedme.
This reporter was from one of the major newspapers in Korea.
He heard about me, butwhen he saw me, it shocked him, and he knew from reporter's instinct thatthis could be a big story.
And the next day, on March 5th, this very big newspaper in Korearan my story on the front page.
NEIL DeGRASSE TYSON: The attention made himimmediately recognizable throughout his country.
MIKE GURNIS: As time went on, he then assumedthis greater and greater role to become a spokesperson for disabled people within Korea.
NEIL DeGRASSE TYSON: He now hosts his ownradio show, writes a column on disability in South Korea's biggest newspaper, and he'swritten a popular book about his work in the sciences.
WOMAN: I was incredibly moved by your book.
SANG-MOOK LEE: I feel very fortunate thatI had an opportunity to reevaluate myself at that moment in my life.
I asked myself,"What can I do to give back? What can I do actively to give back?" NEIL DeGRASSE TYSON: Sang-Mook's biggest projectis a multimillion dollar undertaking, funded by the South Korean government, and it's findingways to help other handicapped South Koreans get back in the workplace.
SANG-MOOK LEE: Why do so many disabled studentsonly take the civil service exam? We need to lead more of these students to go intocomputers and science.
NEIL DeGRASSE TYSON: As part of this program,he's working to discover and develop technologies for the handicapped, including Korean voicerecognition software and robotic limbs.
SANG-MOOK LEE: You and I may run a shop.
NEIL DeGRASSE TYSON: In a city where Sang-Mookoften has to bring his own ramp just to get around, there's still lots of work to do.
SANG-MOOK LEE: It is very difficult, you know?Basically, we have to remodel Seoul.
NEIL DeGRASSE TYSON: But this hasn't stoppedhim.
His love for science has him globetrotting once again.
He recently made his first overseastrip since his accident, to an international science conference in San Francisco.
MIKE GURNIS: That he can come to an internationalmeeting, fly across the Pacific, interact with his colleagues, present his scientificwork, it does symbolize he is now part of the community of scientists, once again.
NEIL DeGRASSE TYSON: In fact, Sang-Mook hasmajor research trips planned to explore underwater volcanoes in Tonga and mid-ocean ridges inthe Pacific Antarctic.
And although he no longer sails the seas himself, Sang-Mook canstill be the captain of his crew.
SANG-MOOK LEE: Now that I'm confined to wheelchair,I cannot go directly to those places.
But nowadays with the development of Internet,satellite communication, I'm able to participate in many of the cruises, without going directlyto sea.
I can enjoy science without getting seasick.
Many people heard of my story, that I wasseverely injured, and they doubted that I would ever come back.
But with the new programsthat are opening up, they will see a lot more of me.
NEIL DeGRASSE TYSON: Before we leave, we'dlike to hear your perspective on this episode of NOVA scienceNOW.
Log on to our Web siteand tell us what you think.
You can watch any of these stories again, download additionalaudio and video, explore interactives and hear from experts.
If you want to get thescoop on upcoming broadcasts and find out what goes on behind the scenes, you can signup for the weekly e-newsletter at PBS.
Org.
That's our show.
We'll see you next time.
Source: Youtube
NOVA scienceNOW : 53 - Sleep, First Primates, Earthquakes in the Midwest, Profile: Sang-Mook Lee
