Why Are Peppers Hot?
Can You Beat Jet Lag?
How Do Bees Fly?
Why Does Traffic Jam?
Sand to Nuts
ALAN ALDA: Just a few minutes ago I was cruising down this highway
with nothing in front of me, and now look. Did you ever wonder
how traffic jams materialize out of nowhere like this?
ALAN ALDA: (Narration) Or did you ever wonder why peppers taste
ALAN ALDA: Smooth
ALAN ALDA: (Narration) Don't you wish you could beat jet lag --
even if it means lighting up your legs? Have you noticed bees
can fly -- though science still doesn't quite know how?
ALAN ALDA: You really do love sand…
ALAN ALDA: (Narration) And what makes sand so much fun?
ALAN ALDA: I'm Alan Alda. Join me now as Scientific American Frontiers
attempts to answer some of Life's Little Questions.
ARE PEPPERS HOT?
ALAN ALDA: (Narration) It's good to know that scientists are trying
to solve the really big mysteries of life. How did life begin?
When will the universe end? Will we ever make a robot that's
smarter than we are?
ALAN ALDA: Now we like big questions as much as the next science
show. But this time, we've set our sights firmly on the trivial
- on the fascinating little questions that crop up in everyday
life. Except we got a surprise - which makes us wonder if
there are any truly trivial questions in science. Because,
as we quickly discovered, one thing keeps leading to another.
ALAN ALDA: (Narration) Take the first question we asked. It's why
we're here in Santa Fe, New Mexico, at a food festival that
celebrates what's practically the state food - the chile pepper.
The question is of great personal interest to me. But it isn't
one you'd imagine leading to a medical breakthrough.
ALAN ALDA: So here's the question: Why are peppers hot? Well, why
are they hot?
BOSLAND: Chiles are hot because they have a compound, or a
set of compounds, called capsaicinoids that's found inside
the fruit, along the placenta. And contrary to a lot of beliefs,
the walls have no heat, the seeds don't have any heat, they're
only in this one little area here - where this orange coloring
is? - that is the capsaicinoids. So the more orange, the hotter
the chile. We think in nature, the plant evolved this to keep
mammals from eating the fruit, because when the seeds pass
through a mammal's digestive tract, they're destroyed. And
so - but birds can come along, pick the fruit off, eat it
and then spread the seeds and put like a fertilizer pellet
ALAN ALDA: So the capsaicin in pepper, which taste so hot to us
and taste so good to me, is really to keep me from eating
ALAN ALDA: It's to keep mammals away and get birds to concentrate
on them, because that's how the seed spreads?
BOSLAND: Exactly. The birds don't taste capsaicinoids; they
don't sense the heat. What they're doing is getting a very
good source of vitamin A.
DEWITT: The flavors and the aromas are why the world's cuisine
have gone to chile peppers. In other words, within a hundred
years after Columbus brought back the first chile pepper seed
from the New World, they spread to the Old World, and completely
went around the world in less than a hundred years, and what
would curries be without chile peppers, what would Thai food
be like without chile peppers?
ALAN ALDA: I know, I think of Schezuan food, one of my favorite
foods, I can't imagine it without chile peppers, but they
ate there without chile peppers for thousands of years I guess.
DEWITT: Thousands of years.
ALAN ALDA: (Narration) My hosts' plan is for me to sample some
of the different peppers here so that I can appreciate their
subtleties. But for me subtlety and peppers don't mix. So
offered a choice of mild, medium or hot…
ALAN ALDA: Let's get hot right away.
DEWITT: OK, this is the Capsicum picatum, I'll let you try
this. Also know as aji in South America.
ALAN ALDA: It's good.
DEWITT: Now you said you liked hot peppers.
ALAN ALDA: Yes I do.
ALAN ALDA: (Narration) I'm not the only one here playing with fire.
ALAN ALDA: When somebody eats a pepper that's too hot for them,
what do you recommend to calm down their mouth?
DEWITT: Well there's a lot of folk remedies. People say if
you eat sugar, or if you drink a lot of beer you won't care
how hot it is. But mostly it's dairy products that help you,
and the thicker, the heavier the dairy product the better.
Like yogurt for example is good, sour cream is very, very
good, and that's one of the reasons sour cream is served with
enchiladas out here in New Mexico for the people who get burned
BOSLAND: We're gonna make you into a connoisseur…
ALAN ALDA: (Narration) Paul and Dave are still determined to teach
me the fine art of pepper tasting. But I get the horrible
feeling it's already too late.
BOSLAND: The three areas to look for is the front of the mouth,
mid mouth and the back of the throat, the throat area.
ALAN ALDA: Tastes like oatmeal. I don't taste anything.
DEWITT: Oh, we burned your taste buds with the hot one…
BOSLAND: Well let's try this one. We'll see what happens here.
It's a little hotter now.
ALAN ALDA: OK…Tomato sauce.
DEWITT: We burned you out, that's what the problem is. It
may be several hours before your palate gets back to normal.
ALAN ALDA: Why are we in red light like this?
ALAN ALDA: (Narration) Burned out my palate? This sounds serious
-- which is why I find myself sitting in a very strange room
ALAN ALDA: This is very futuristic.
KING: Yes it is.
ALAN ALDA: Oh look, there are little screens down there.
ALAN ALDA: (Narration) I've come here to check my heat-sensing
abilities against some of the best-trained tongues in the
world, belonging to the members of the pepper-tasting panel
at one of the nation's largest spice companies, McCormicks.
Silvia King is in charge.
KING: Everybody get set, and go.
ALAN ALDA: (Narration) We start with what's reckoned to be a mild
solution of the hot pepper chemical capsaicin. SYLVIA KING:
ALAN ALDA: (Narration) We're instructed to assign it a five on
a heat scale of zero to fifteen.
KING: So is everybody ready? Rinse with water and rinse with
ALAN ALDA: (Narration) A cracker, hmm? What happened to the sour
ALAN ALDA: Does the cracker really clear out the sensation of heat?
KING: It will help. Get ready for your strong reference.
ALAN ALDA: (Narration) The idea here is to tune our tongues to
a standard set of heats -- concluding with a dose of capsaicin
scoring a respectable 13 on the heat scale.
ALAN ALDA: Smooth!
ALAN ALDA: (Narration) OK, with our tongues now calibrated, it's
time to see how we all rate a sample from a real hot pepper
-- which is why, by the way, the light's red -- to disguise
the sample's color, so it won't influence our score.
KING: Set and go.
ALAN ALDA: (Narration) I'll give it an 8. And my fellow tongues?
GILLETTE: I would give it about a 7.9
7.5…about a 7…7.2…about a 7.6…
ALAN ALDA: (Narration) Well that's a relief. My tongue seems right
in line with the experts'.
TASTERS: 7.5…7.8…7…about an 8.2.
ALAN ALDA: I'm sort of amazed that I even could taste anything
in the mild one, you know. I was really afraid when I came
in here you'd say this is the mild one and I'd say, no that's
ALAN ALDA: (Narration) Of course, the spice company didn't set
up the heat-sensing panel just for my peace of mind. It's
one of several ways they check the heat of all the peppers
they buy, so that their customers don't get a nasty surprise
once the pepper's ground into powder or flakes. Still, heartened
that my tongue has survived years of hot pepper pummeling,
I took it to a specialist.
ALAN ALDA: So if I can taste this as extremely bitter I'm a…
BARTOSHUK: A supertaster.
ALAN ALDA: I'm a supertaster. If I can't taste anything…if it tastes
like a piece of paper…
BARTOSHUK: You're a non-taster.
ALAN ALDA: Oh boy.
BARTOSHUK: And if it's something in the middle, you're a medium
taster. Be sure the paper gets really moistened with your
saliva and moves all around so it covers your whole tongue.
Are you tasting anything?
ALAN ALDA: It's bitter.
BARTOSHUK: Ah yes, yes. Authentic supertaster.
ALAN ALDA: It's really bitter.
BARTOSHUK: Oh oh, alright, I think now's the time to take
ALAN ALDA: If I'm not a supertaster, I don't want to know. This
is close enough.
ALAN ALDA: (Narration) Only one person in four is a supertaster…
ALAN ALDA: Blech!
BARTOSHUK: I can't share that experience with you because
I'm a non-taster.
ALAN ALDA: (Narration) While another one in four, like Linda, doesn't
taste the paper at all. The paper was only the beginning of
my tongue check-up - next came blue food coloring.
BARTOSHUK: OK, swallow. Move your tongue in your mouth a couple
of times and swallow a couple times, and that will distribute
the dye. And then we'll have a look. Stick your tongue out.
Oh, magnificent, the staining is absolutely perfect, I can
see the pink fungiform papillae. Your tongue looks like it's
tiled in fungiform papillae. You definitely look like a supertaster.
ALAN ALDA: I'm a supertaster.
ALAN ALDA: (Narration) The fungiform papillae are little sprouts
on my tongue. Each one harbors a half-dozen or so taste buds,
with nerve fibers connecting them to my brain. While some
of these fibers convey the sense of taste, most of them don't
sense taste at all, but pain. Which brings us back to hot
BARTOSHUK: You are feeling way more pain from eating a red
pepper than I would, for example.
ALAN ALDA: Because I have more of these structures.
BARTOSHUK: That's right. You have way more pain fibers so
you perceive way more pain.
ALAN ALDA: This is really weird because I eat far more red pepper
on my food than anybody I know.
ALAN ALDA: (Narration) Now of course it may be that I just like
pain more than most people. But there's another explanation,
which goes back to that hot pepper I ate in Santa Fe. Because
it not only knocked out my sense of taste. After the initial
burn, it actually numbed the pain fibers that nestle around
my taste buds.
ALAN ALDA: Now that this is cooled a little I put the pepper in?
ALAN ALDA: (Narration) Which is why I'm helping make hot pepper
candy. A dash of cayenne pepper before the traditional taffy
ALAN ALDA: Both thumbs, I have both thumbs in the taffy. I can't
get my thumbs out of the taffy.
ALAN ALDA: (Narration) And the result is a candy that Linda Bartoshuk
uses to treat patients with painful mouth sores. The candy
was the idea of a student of hers, but others had thought
of it before.
BARTOSHUK: If you go back and read accounts of Aztec medicine,
you'll find out that the Aztecs were using chile peppers mixed
with honey to treat sores in the mouth. My guess is that every
culture that has ever consumed these chile peppers has figured
out that they are really good analgesics. We're just the last
in a long line of people who've looked at that.
ALAN ALDA: (Narration) One man who's that happy researchers are
again exploring the pain-killing properties of peppers is
a long-term survivor of AIDS, living in San Francisco. A few
years ago, he began suffering agonizing pain in his feet due
to a condition known as neuropathy.
The pain was very, very deep inside my feet, just underneath
the toes. The best way I can describe it was that there was
broken glass in there, on the nerves, to the point my life
was just becoming very sedentary.
ALAN ALDA: (Narration) An active runner and volunteer with the
AIDS quilt project,
Apodaca became housebound, his pain controllable only with
I thought that if this pain continues, and if all they can
do for me is tranquilizers, then I just didn't want to go
on any further. And that's pretty much where I was until I
met the pain management crew and Wendye Robbins .
ROBBINS: An interesting day to be doing this from a symbolic
perspective. This is the start of the Jewish calendar.
ALAN ALDA: (Narration) Wendye Robbins, an anesthesiologist, figured
if hot peppers numb pain in the mouth, why not elsewhere?
ROBBINS: That was part of the originality of the invention,
was realizing that the same nerve fibers that are present
in the mouth and signal hot or spice when we eat them are
also present on the foot and therefore can probably be interacted
with in the same way.
ALAN ALDA: (Narration) Geppetto's treatment begins with a powerful
local anesthetic smeared on his feet.
ROBBINS: Before we put capsaicin on him we have to make sure
he's pretty numb. Otherwise the capsaicin itself would be
ALAN ALDA: (Narration) The mask protects against the fumes from
the capsaicin cream.
ROBBINS: This is a hundred fold more potent than the stuff
that's available commercially. This is 7.5% by weight. If
I was to touch this to your foot, or to the foot of anyone
else who wasn't anesthetized, it would be excruciatingly painful.
ALAN ALDA: (Narration) While we wait for Geppetto's feet to bake,
we've time for a quick visit with another team of San Francisco
scientists. With research materials bought from local supermarkets,
their goal was to find the molecule in our bodies that responds
to peppers' heat. Among the peppers David Julius and Michael
Caterina tested was the habanero, the hottest of all.
JULIUS: Very pungent. Tearing my eyes. Making it a little
hard to breathe. All for science, you know.
ALAN ALDA: (Narration) What the researchers have found is the molecule
in our nerves that hot peppers activate when they cause their
painful burn. The molecule sits like a trapdoor on the surface
of the pain fiber. Capsaicin unlatches the door, allowing
calcium ions to rush in -- and so firing off the pain message
to the brain. Here's what happens when capsaicin is added
to living cells that are cued to light up when the trapdoor
CATERINA: If you were to take the neurons that normally respond
to pain in our bodies and subject them to this same sort of
assay, this is exactly what they would look like. They would
start off purple and then when you added capsaicin to them,
they would all light up. A silent scream.
ALAN ALDA: (Narration) The researchers discovered that very hot
water also makes cells give this same response. In fact, the
original job of the trapdoor molecule in our bodies may have
been to detect and warn of dangerous heat. So here's the ultimate
reason peppers are hot - capsaicin fools our cells into thinking
they're on fire! Right now Geppetto's feet know the feeling
only too well.
I'm beginning to feel a very, very, very hot sensation on
my feet right now.
ALAN ALDA: (Narration) But just as the hot pepper candy relieves
mouth sores, so Geppetto's much more dramatic treatment should
relieve his much more devastating pain - once the burn wears
The first time we did it, my initial feeling when I got home
was that the pain was so bad from the capsaicin that I couldn't
realize that it was going to get any better. And as the third
day came around and I was able to put on shoes comfortably
for the first time, it was like being born again.
ALAN ALDA: (Narration) This time
was running again within the week - and if his previous treatments
are a guide, he'll remain virtually pain-free for months.
Meanwhile, Wendye Robbins hopes that many other patients with
debilitating pain can also be treated with pepper's chemical
heat. You see what I mean? One thing in science just seems
to keep leading to another.
YOU BEAT JET LAG?
ALAN ALDA: One thing we do a lot on this show is fly across time
zones. A two or three hour time change isn't so bad. But a
flight to Europe or Asia or Africa can wreck me. So here's
our next question - and I'm really interested in this one!
Is there a simple way to beat jet lag? It turns out there
might be. And the solution involves light.
ALAN ALDA: (Narration) Now of course, on this show nothing's
ever easy. These wires, for instance, are to check that I
stay awake during what has to be one of the weirdest experiments
the Frontiers producers have ever talked me into.
ALAN ALDA: So what do you do, if you see me falling asleep,
you come in and give me a nudge, or what?
MURPHY: Yes, we do. We're also collecting during this time
saliva samples, to measure the hormone melatonin…
ALAN ALDA: Saliva samples…
PATRICIA MURPHY: So we come in and bother you every half-hour
ALAN ALDA: (Narration) See - I knew there was going to be more
to this than just getting wires on my head.
ALAN ALDA: I find out about his stuff in stages. We're going to
do something having to do with light and sleep, and then I
find out they want my body fluids.
MURPHY: We could have done it with blood or urine, but we
chose saliva. These lights are used for the way we used to
do photo therapy…
ALAN ALDA: (Narration) Now it's hard to imagine falling asleep
in front of a bank of glaring lights- which is actually the
reason for the experiment I'll be in. But lights like this
can shift a person's internal clock.
CAMPBELL: We've known since about 1980 that when light is
shone in the eyes, then it resets the biological clock. It's
just like taking your watch and pulling the stem out and twisting
it. And it happens quickly, within 24 hours, probably much
more quickly than that. And by resetting the biological clock
you also set the timing of any number of physiological activities,
one of which is sleep.
ALAN ALDA: (Narration) Your biological clock is a pinhead-sized
cluster of cells deep in your brain. The conventional wisdom
is that it's a signal from the eyes that resets the clock.
Which means there was a problem for people who wanted their
ALAN ALDA: They didn't like sitting in front of bright lights?
MURPHY: Right, your behavior is constricted here, you have
to sit and make sure you're getting the light to your eyes,
so you can't look down and read or knit.
ALAN ALDA: (Narration) But what if the bright light didn't need
to be in your eyes at all?
ALAN ALDA: This is interesting, this is a weird looking light,
it seems green.
CAMPBELL: It's a blue light they use for the treatment of
ALAN ALDA: (Narration) So here I am having lights designed for
newborn babies to lie on, wrapped around, of all things, the
back of my knees.
ALAN ALDA: You know my knees look pretty cute, come to think
CAMPBELL: We're going to tilt you back and slide you under.
ALAN ALDA: I think I saw an ad for this on late-night TV.
ALAN ALDA: (Narration): The black drape and putting the light sources
under the table is to make sure volunteers for the experiment
don't know whether the lights are on or not.
MURPHY: For the next three hours, we to expose you to the
ALAN ALDA: (Narration): The extraordinary hypothesis Scott and
Patty are testing is that light on the back of my knees will
work as well as light in my eyes in resetting my biological
clock. My job is simply to avoid falling asleep for the next
ALAN ALDA: Not so fast Louie.
ALAN ALDA: (Narration) Which is why they're showing me a movie.
MURPHY: OK, we're going to give you a tube in which we'll
have you collect a saliva sample.
ALAN ALDA: Don't watch -
this is personal. Here, I've filled this with some really
great looking goo.
MURPHY: Thank you.
ALAN ALDA: (Narration) My saliva's used to measure the hormone
melatonin, one of the things controlled by the biological
clock. When Scott and Patty first did this experiment, they
were astonished at the result.
CAMPBELL: The outcome was that light to the backs of the knees
had the same effect on the biological clock as light presented
to the eyes. We were able to both reset the clock to a later
time and to an earlier time depending on the time we gave
ALAN ALDA: Now this business of putting it on the back of the knee,
it doesn't have to be on the back of the knee to get this
effect, does it?
MURPHY: No, we don't think so. We're not sure, but we don't
think so. We were looking originally for a place to put the
light that was far enough away from the eyes that we could
control that factor. We wanted to make sure that light wasn't
getting to the eyes. So we chose a place…
ALAN ALDA: So in other words to make sure that it's somehow through
the skin and not through the eyes that you're having this
MURPHY: Right. And also there's a theory that if there is
some signal getting to the brain from a place other than the
eyes, that it might be carried in blood.
ALAN ALDA: (Narration) And the back of the knee happens to be a
place where lots of blood runs close to the surface. One explanation
for the result is that blood is getting light's message from
the skin to the brain as some sort of back-up system for the
more direct route from the eyes.
CAMPBELL: There's no question that in humans light in the
eyes is the preferred evolutionary choice. But what our finding
suggests is that there are possibly other ways to get that
light to the clock.
ALAN ALDA: (Narration) The experiment hasn't yet been confirmed
by other researchers. But if it's true, the discovery could
help people like me who have trouble sleeping through the
night. As Frontiers discovered a couple of years ago when
we were trying to record my dreams, I often wake up in the
middle of the night and find it hard to get back to sleep.
Many people with this problem have biological clocks that
give their "get ready to wake up" signal in the middle of
the night. Light can push it later - but the best time for
the light is right before the signal's given.
CAMPBELL: Now the interesting thing is that giving light at
that time means that we have to give light in the middle of
the night to have the biggest bang for our buck, if you will.
And it's impossible to sleep with light in your eyes - you
know that. So one of the things that our finding may prove
useful for is presenting light at a more appropriate time
for resetting the clock during sleep.
ALAN ALDA: (Narration) And if you can reset the clock during sleep,
then maybe one day light pads could help us fix the problem
we started with -- jet lag. It could give us a whole new reason
for the in-flight movie!
DO BEES FLY?
ALAN ALDA: I read somewhere once that aeronautical engineers had
proved that bumblebees can't fly… Isn't that great? What that
really proves I guess is that bees are smarter than engineers.
But it also leaves us with another of life's little questions.
How do bees fly?
ALAN ALDA: (Narration) These particular bumblebees are collecting
pollen in the garden of Downing College at Cambridge University
in England. And Charlie Ellington, a biologist rather than
an engineer, also once confirmed they're doing what's apparently
impossible. Poring over slow motion film of flying bumblebees,
Charlie spent countless hours measuring the exact position
of the wings at every beat.
ELLINGTON: The most mind-boggling tedious thing you can ever
do in your life, is analyze these films frame by frame. And
what we would find is typically that the bumblebee wouldn't
even be able to get up off the ground, or if it was up in
the air it would fall down to the ground. Their wings are
too small and they beat too slowly for enough lift to be generated
conventionally to keep them up in the air.
ALAN ALDA: (Narration) And bumblebees, it turns out, aren't alone
in defying the conventional laws of flight. Most other insects
do too, flying along happily on wings that just shouldn't
be up to the job. But finding where the missing lift is coming
from was impossible with insects as small as bees.
ELLINGTON: So we had to change over to a bigger insect that
flaps its wings more slowly, and in fact we chose this one
for that. It's a big hawkmoth, Manduca sexta, it has a wingspan
about 10 centimeters, it beats its wings about 25 time a second,
and it makes the experimental work so much easier. You can
see what's happening around the wings. And what we saw was
that the airflow came up, and as it hit the leading edge of
the wing it spiraled and swirled off of it. Just like a whirlwind
or tornado it's a low-pressure region and things get sucked
into low pressure. In effect it's sucking the wing up like
that and this is producing two or three times more lift on
ALAN ALDA: (Narration) It turns out that this swirl of air lifting
the wing is something aeronautical engineers know only too
well. In airplanes it causes something called delayed stall.
ELLINGTON: This is delayed stall over the main wing of the
plane, like that. And that's exactly what's happening over
the insect wings, where you're getting a flow swirling around
the leading edge, generating lots of lift. But on a wing like
this, that lift builds up and breaks away, and then it drops
out of the air because there is no lift anymore.
ALAN ALDA: (Narration) So for a human-engineered wing this extra
lift is strictly temporary - and can be dangerous. But for
ELLINGTON: The trick that the insect has is this large lift
it has briefly, the insect can prolong.
ALAN ALDA: (Narration) Finding out how an insect keeps the extra
lift meant taking another leap in scale.
ELLINGTON: This is the Flappper. It's a big mechanical model
of an insect, based on the hawkmoth. It's got a one-meter
wingspan instead of just ten centimeters, flaps its wing once
every three seconds instead of 25 to 30 times a second.
ALAN ALDA: (Narration) Exquisitely engineered, the Flapper's computer-controlled
motors and gears not only flap each wing but bend and flex
ELLINGTON: The wing has been designed so that when twisted
at the base and tip, it changes shape in between in the same
way that the real insect does.
ALAN ALDA: (Narration) Using smoke to see the airflow, Charlie
confirmed the miniature tornado around the wing. But the smoke
also revealed something else - the fact that the tornado is
sucked along the wing from base to tip.
ELLINGTON: Because it moves out to the tip, it doesn't grow
so large here that it breaks away and the wing stalls. Instead
it gets sucked out and kept under control that way.
ALAN ALDA: (Narration) So the swirl of air stays stuck to the wing
- along with the extra lift it provides.
ELLINGTON: So the smoke gives us a qualitative picture of
what's happening, you can see where the air is flowing. But
what we need to do now is measure it so we can study it more
exactly. One way to do that is to have little particles floating
around in the air that you can track. And that's what these
are - little soap bubbles filled with helium to make them
neutrally buoyant and also filled with smoke to make them
white or at least gray.
ALAN ALDA: (Narration) And so now, with 19th century books on insects
lining the walls of its home, the Flapper untiringly beats
its wings amid a gentle blizzard of bubbles. Because the path
of each bubble can be tracked in three dimensions, Charlie
Ellington hopes they will reveal exactly how much extra lift
the spiral of air provides - and so finally allow insects
to fly -- officially. Also flapping its wings for science
is a real insect -- a fruit fly -- housed in the laboratory
of Michael Dickinson -- a confessed fly fanatic.
DICKINSON: I think flies can perform certain maneuvers that
are just simply unsurpassed. And we take these for granted
because they're so common. But consider a fly landing on a
ceiling, or a hoverfly hovering with pinpoint accuracy over
a daisy. These are extraordinary feats of locomotion.
ALAN ALDA: (Narration) To find out how flies perform their extraordinary
feats, Michael starts by chilling fruit flies to anesthetize
them, then tucks them into a little chamber under his microscope.
DICKINSON: I'm going to apply a little gentle suction to hold
him down. The next step is to put a little tiny drop of this
light-activated glue, just behind the head. And the secret
is to put just the right amount.
ALAN ALDA: (Narration) The glue - activated by UV light - was developed
for dentists, but work very nicely on fruit flies.
DICKINSON: So there you have a fly on a stick.
ALAN ALDA: (Narration) Stick and fly are slid into a little video
theater, designed with a fly's view of the world in mind.
DICKINSON: I've just aligned the fly so that we can pick up
its wing beats with a photosensor, and now I'm starting to
engage the feedback so it can fly itself through a little
virtual world, if you will.
ALAN ALDA: (Narration) The fly's wings can't move their owner,
but they do control the movement of the vertical stripe. When
the fly banks left, the stripe moves to the right, and vice
versa. The V-shaped chevrons are under Michael's control.
DICKINSON: The chevrons are now moving down, and so the fly
thinks that its moving upward. The chevrons are now moving
up, and the fly thinks its moving down.
ALAN ALDA: (Narration) You can hear the fly's wingbeat change as
it tries to dive or climb in response to thinking it's rising
or falling. Right now the fly thinks its coming in for a landing
as it's offered a tiny square of paper soaked in sugar water
- an in-flight refueling stop. Michael Dickinson runs this
fruit fly test pilot program to discover how they respond
almost instantly to changes in their environment - not just
what they see, but what they feel. Here the fly's being thrown
around as it tries to steer for the stripe, and again you
can hear the wingbeat change as it tries to keep flying straight
and level. The fly's extraordinary skills depend crucially
on what millions of years ago was another pair of wings. Called
halteres, these dumb-bell-like structures have evolved from
rear wings into gyroscopes, able to sense what's happening
to the fly in the air, and providing almost instant feedback
to the front wings so they can immediately respond. Studying
this flight control system in detail takes a bigger fly -
and this blowfly takes its test flights rigged with minute
electrodes in its muscles. It's also given a metronome to
fly toward and a flow of air to fly through.
BELINT: They don't like to be tethered, and it's a problem
to get the animals to feel like their flying. All this complicated
machinery is to get the animal to feel like it's free.
ALAN ALDA: (Narration) What you hear now are the blowfly's flight
control muscles responding as it tries to steer toward the
metronome, aided by its halteres, which are visible in slow-motion
video. The lab is now focusing on how these gyroscopes work,
enabling the fly to respond to hazards like a fly swatter
in much less than the blink of an eye.
DICKINSON: I often go with members of the lab to see science
fiction movies, especially about space aliens, which are extraordinary
creatures fabricated in Hollywood. But I think all you have
to do is go poke in a garbage can, and you're going to see
animals that are much more extraordinary and fantastic than
anything you're going to see in a Steven Spielberg film, and
I'd rank flies as being right up there.
ALAN ALDA: (Narration) But for this fly, it's time for a rest.
BELINT: When it's ready to land, I give it back its world.
Home sweet home.
DOES TRAFFIC JAM?
ALAN ALDA: (Narration) Most traffic jams come as no surprise.
MORGAN: If you're northbound you've got some slowdowns on
Route 24 and down here right below us on Route 95…
ALAN ALDA: (Narration) At rush hour, the sheer volume of traffic
chokes up merges and intersections in patterns that are only
too predictable and familiar.
MORGAN: …expect some severe onramp congestion. Joe Morgan,
ALAN ALDA: (Narration) But then there's another sort of traffic
ALAN ALDA: Just a few minutes ago I was cruising down this highway
with nothing in front of me, and now look. Did you ever wonder
how traffic jams materialize out of nowhere like this? Another
one of life's little questions. It may seem strange that we're
trying to find out about traffic jams on a road that's out
here in the middle of nowhere. But as a matter of fact this
road was put here because it leads to a very remote place.
ALAN ALDA: (Narration) The place is the Los Alamos National Laboratory,
built here in the Jemez Mountains of New Mexico over 50 years
ago to develop and build the atom bomb.
BARRETT: Down over this way is a collection of houses that
the senior scientists lived in, people like Robert Oppenheimer…
ALAN ALDA: (Narration) There are still a lot of scientists here
at Los Alamos, but now much of their research is on less apocalyptic
ALAN ALDA: We're driving down the road, and traffic slows down
to a halt. And then it picks up again, and you look for what
the problem was - there must be a wreck by the side of the
road - and there's nothing. Where did it come from? And I
know people wonder about this. I was telling my daughter we
were going to talk about this, and I'm saying, you slow down
and you look for the thing and there's nothing there, and
she said, yes, yes, that's it, I always wonder that too. What's
NAGEL: Why didn't you bring her?
ALAN ALDA: She's already married. Tell me why it happens.
ALAN ALDA: (Narration) Kai Nagel works on a project that simulates
traffic in a computer.
NAGEL: What we see here is a simulated freeway. And we see
cars driving on that freeway. And what we see is a second-by-second
snapshot of the situation, so this is why the cars are jumping.
ALAN ALDA: (Narration) Most of the time, the cars on this single
lane highway go along just fine. But every now and then, when
the traffic gets dense enough, one or two cars happen to slow
NAGEL: Everybody slows down from time to time, sometimes it
ALAN ALDA: When you get enough of that happening in the same space
then you get a little knot of slowing down. So then what happens
NAGEL: What happens here is we suddenly have someone who needs
to slow down even more. What you eventually get is somebody
who has to stop. And you see how the red knot keeps growing.
ALAN ALDA: New cars keep coming in, coming to a standstill, while
other cars get out of the knot. But that knot seems to move
back down the highway.
NAGEL: Once you run into that jam, it can be totally disconnected
from the original cause.
ALAN ALDA: Oh right, yes, so in other words, the original knot
of traffic, the original jam, could have occurred by an exit
ALAN ALDA: But then it propagates backwards, it maybe travels a
mile back from the exit ramp, and I look out and I don't see
anything, I see no reason, I don't see an exit ramp, I don't
see an accident, I can't understand why I've just been stopped.
ALAN ALDA: And it's because it started way up there, a mile up
ALAN ALDA: That's really interesting. Stuff happening that we experience
ALAN ALDA: (Narration) But computer simulations today go far beyond
answering why traffic jams appear out of nowhere. The Los
Alamos labs' immensely powerful computers, built to simulate
nuclear explosions, have recently been turned loose on simulating
the traffic flow within entire cities.
BARRETT: So TRANSIMS is a suite of simulations that simulates
not just traffic, it simulates the populations, the roadway
networks the populations are organized around, the individuals
trying to move…
ALAN ALDA: (Narration) This for example is a simulation of a 25-square-mile
section of Dallas. Every vehicle on the highway has its own
destination, and has to deal not only with intersections and
traffic lights, but also with every other virtual vehicle.
BARRETT: So you find effects like this. There are lots of
people that want apparently to get off at this place, and
we have a jam backing up on the freeway and causing congestion,
which will eventually break up but will build up to be pretty
bad before it does.
ALAN ALDA: (Narration) The Dallas project is one step toward even
more ambitious simulations - like one now underway to put
the entire city of Portland, Oregon, into a computer. And
not just Portland's system of roads and mass transit, but
all of its people.
ALAN ALDA: That red part is where the people live, or where they're
BARRETT: Exactly. We're going to go down and actually create
synthetic households of individuals that correspond to the
census in this region right here.
ALAN ALDA: (Narration) The Portland project is in fact creating
hundreds of thousands of synthetic families, with every family
member trying to figure out for him or herself how to get
around the city in the course of their simulated lives.
BARRETT: We can assign the guy a workplace and an activity
list through the day that corresponds to what people of that
kind in that block group do.
ALAN ALDA: And these are all his destinations during the day.
BARRETT: During the day, this guy starts at home, goes to
work, at lunch time he goes to lunch, goes back to work…
ALAN ALDA: So he has destinations and times to hit those destinations.
ALAN ALDA: (Narration) Once the daily schedule's been created,
the computer turns it into travel plans. It's a mind-boggling
notion - hundreds of thousands of synthetic people struggling
away inside a supercomputer, trying to figure out how to get
to work, to the doctor's office, the shopping mall; each having
to cope with all the other simulated citizens going about
their daily business. It's just like real life - and that,
of course, is the whole point. TRANSIMS job is to provide
city planners with an immensely powerful tool - for predicting
the effect of a new traffic light all the way up to building
a brand new highway. These little questions of ours just refuse
to stay trivial.
BARRETT: Mobility is an essential part of being a human. And
certainly an essential part of how we impact our environment
and how we interact with one other, every day.
ALAN ALDA: (Narration) In few cities is that more true than in
Boston, where the Central Artery is a commuter's nightmare.
But the elevated freeway is about to go underground, in one
of the most expensive construction projects in history. I
was met at Boston airport by project-wide engineer
SERGIU LUCHIAN:, whose job it is to make sure traffic flows
smoothly once the new tunnels are completed.
LUCHIAN: We're now going through the tunnel into the city
of Boston. And the tunnel is fully equipped…
ALAN ALDA: (Narration) This is the Ted Williams tunnel, the first
part of the project to be opened to traffic. It's equipped
with cameras in the ceiling and detectors under the pavement
to monitor traffic flow. The entire network of some 160 miles
of new traffic lane, mostly underground, will be watched over
from a control center that makes NASA's mission control look
quaintly old-fashioned. Sitting here, operators can monitor
every foot of the highway, and display what's happening on
a huge video wall. Some 500 cameras can each be individually
controlled, even zooming in close enough to read license plates.
ALAN ALDA: I'm going to be much more careful in tunnels from now
ALAN ALDA: (Narration) The project is so complex that it's been
simulated on a computer at nearby MIT - a simulator that's
constantly consulted by Sergiu and his colleagues.
ALAN ALDA: There, there, that's traffic coming up - those little
dots are cars.
LUCHIAN: Those are cars.
ALAN ALDA: But they're make-believe
cars. They're virtual cars.
LUCHIAN: They're virtual cars, but they are in full rush hour
in the year 2004. And there are also different types of cars.
You can see dual tractor-trailers over here, buses, trailers,
ALAN ALDA: Oh look, one says wash me!
ALAN ALDA: There's a couple of lanes where they're moving slowly
and right next to it are lanes where they're moving faster,
and they're looking for ways to get in front of each other,
LUCHIAN: That's right.
ALAN ALDA: (Narration) In fact, the behavior of the simulated drivers
is based on observations of the real thing. The MIT researchers
videotaped hours of Boston drivers, and many of the vehicles
in the simulations exhibit the same notorious habits. The
MIT simulator has been especially useful in checking out the
tactics the control center will adopt in the event that things
ALAN ALDA: What's your worst nightmare here? I mean, this is all
LUCHIAN: The worst thing that can happen is that on a hot
day, if you want, an obstruction that will block one of the
tunnels. This is where we simulated that stoppage, that block…
ALAN ALDA: (Narration) The plan is to close the tunnel entrance
as soon as an accident is detected. Only when the block is
cleared will traffic again be allowed to enter. The question
was - how soon should the tunnel be reopened?
LUCHIAN: The initial set-up was that the moment this was clear,
they'd just turn that light green and everybody would just
shoot down the tunnel at 50 miles per hour.
ALAN ALDA: (Narration) Letting in the traffic immediately - the
most obvious strategy - turned out in the simulator to cause
one of those backward waves we saw at Los Alamos. Cars had
to screech to another stop - perhaps causing secondary accidents.
So another strategy was tested -waiting until the traffic
trapped behind the block starts to move before opening the
tunnel entrance. Now the flow of traffic sweeping into the
tunnel is smoother - and the ride faster.
ALAN ALDA: So making them wait until they have a freer flow gives
them a shorter time in the tunnel than if you let them in
as soon as the accident is cleared?
LUCHIAN: That's what the simulator proved to us.
ALAN ALDA: And that's true in real life?
LUCHIAN: That's true in real life as well.
ALAN ALDA: Wouldn't be so good if it was only true in the computer!
LUCHIAN: That's right!
ALAN ALDA: (Narration) It's too bad
though, that real life traffic jams can't yet be freed at
the click of a mouse.
ALAN ALDA: The beach is a great place for thinking up trivial questions.
For instance, have you ever noticed that when you walk in
wet sand, the color of the sand seems to change in a sort
of halo around each footstep? Why is that? It's no coincidence
that this particular little question popped up here, on the
shore of Lake Michigan in Chicago, because at the University
of Chicago are a couple of scientists who just love asking
trivial questions about stuff like… well, stuff like sand.
You really do love sand, eh?
SIDNEY NAGEL: Of course, it's one of the best substances there
ALAN ALDA: What about my question. Why do we get this sort of halo
around our footsteps when you walk on wet sand?
NAGEL: What we've got here is sand in this squeeze bottle.
And we've filled it with water to a little bit higher than
the level of sand. And so, as I squeeze this, what's going
to happen? Normally you would think that everything is just
going to rise. But as you saw with the sand near the lake,
you squeeze it and the water drops below the level of the
ALAN ALDA: That's great. You let go of it and the sand goes down
and you have a layer of water on top. You squeeze it - look
at that water, it seems to go all the way down there and the
sand goes right up
ALAN ALDA: (Narration) The explanation's actually simple. Squeezing
the bottle makes the sand grains move past each other -- and
to do that, they must first move slightly apart. The water
then runs down into the bigger spaces between them. On the
beach, my weight pushed the sand grains apart, and the water
draining away created the haloes. In fact, whenever grains
move, they must first move away from each other. For instance,
only the seeds on the surface of this avalanche have the room
to expand and so to flow. And it's when sand flows that it
really gets interesting.
ALAN ALDA: What is this orange thing?
NAGEL: This is a puzzle, which has orange sand in this plastic
tube, and in the middle of the sand we have this big steel
ball. And the question I have for you is, the ball is on one
side and I want you to get the ball over to the other side
of the container.
ALAN ALDA: OK, so the ball is on this side, I have to get the ball
to this side of the sand, eh?
NAGEL: That's the idea.
ALAN ALDA: OK, so the first thing obviously is to try to shake
ALAN ALDA: (Narration) Obvious perhaps -- but equally obviously,
not effective. Stubbornly, the ball refuses to sink.
NAGEL: Suppose you try it upside down?
ALAN ALDA: It's climbing right up! There it is, there it is, it's
right at the top. OK, what makes it climb up through the and
JAEGER: Great question. And to answer that, we're going to
ALDA: (Narration) The lab we're heading for is the University
of Chicago's Materials Center.
NAGEL: So this is the two dimensional version in a real laboratory
situation of what you saw here.
JAEGER: Let's just turn this thing on.
ALAN ALDA: Look at that, wow! And there it goes, down the side.
I was just going to say, I can see poppy seeds moving down
NAGEL: But this big one can't make it, can it?
ALAN ALDA: No.
ALAN ALDA: (Narration) The only thing going on here is that the
container is being briskly shaken up and down. It's a fancy
version of what can sometimes happen if you shake a can of
mixed nuts. The shaking unmixes them, causing the large nuts
to rise to the top. Remarkably, there's never been a good
explanation for this phenomenon. But a clue came from that
thin downward stream of grains I'd noticed along the wall.
Here's what Sid and Heinrich think is happening. As the grains
are thrown upward, those nearest the wall are dragged against
it, slowing them down. When the grains fall, they're less
densely packed, so there is less drag against the walls. The
result: the grains next to the wall slowly move downward,
setting up a sort of convection current. The current rises
in the center, carrying everything with it. But at the walls
the current is too narrow to take large objects down again,
so they are left stranded at the top. In a shaken can of mixed
nuts, the Brazil nuts present themselves ready for eating.
All very interesting, but…
ALAN ALDA: Suppose mixed nuts is not the most important thing in
your life. What else does this apply to, anything? Or is it
great that we have this understanding of how particles move?
SIDNEY NAGEL: Mixing is a terribly important thing in the
pharmaceutical industry. That is, if you are making pills
out of various powders, you want to mix them. And if you don't
mix them properly, then you'll have some pills that have all
the binder and other pills that have all the good stuff, but
having all the good stuff in one pill is very, very bad.
ALAN ALDA: You could kill somebody.
NAGEL: You could kill somebody with that.
ALAN ALDA: (Narration) A great example of how an apparently trivial
question can lead to a very non-trivial answer. And how about
this one? Why does an hourglass invariably contain sand?
ALAN ALDA: Would anything work in an hourglass? Could I put water
in an hourglass and would I get the same timekeeping ability?
JAEGER: You could put water in an hourglass, of course.
ALAN ALDA: But it wouldn't do me any good…
JAEGER: It would not do the following. It would not be a linear
keeper of time. In other words, what makes the sand here so
remarkable is that no matter how high the filling height is
here, the flow rate at the orifice is always the same. So
if you have markings that tell you time - one minute, two
minutes, three minutes, whatever - they are equally spaced.
That has to do with the fact that most of the weight up here
is unloaded not straight on to the hole, but it is going toward
ALAN ALDA: (Narration) The weight goes to the sides? Hard to believe
- until Heinrich and Sid got my competitive juices flowing
with a simple children's game.
ALAN ALDA: You've really got my interest now…
ALAN ALDA: (Narration): The curved bar - which is like gravity
- pushes down on the wooden discs, representing grains. The
trick is to remove the discs that aren't holding up the bar.
ALAN ALDA: This looks like it's free. Yeah. It's a big one. This
looks like it's very much connected… but his doesn't look
like it's connected. There, I got another one. I'm pretty
good. Now this one I get for free. But it could be all the
way down here. I'm guessing this doesn't connect to anything…
ALAN ALDA: But this must…. Now, that was really a force against
the side, wasn't it?
JAEGER: Correct. And so we started with a force coming down
this way, but we ended up with a force against the walls.
And the material diverted the force against the wall, and
that's why the hourglass has this constant flow rate, because
much of the forces from all the material above the orifice
gets diverted against the walls.
ALAN ALDA: (Narration) One of Sid Nagel's favorite trivial questions
confronted him one day from his kitchen counter.
ALAN ALDA: Are these historic coffee stains here? Are these the
ones that gave you your inspiration?
NAGEL: Oh, they're a day old or so. But when they're as lovely
as this, wouldn't you have trouble wiping them up?
ALAN ALDA: (Narration) Yes, it's true, Sid really does find coffee
stains beautiful -- because they made him wonder why, when
a coffee spill dries, it always leaves a ring. Enough of Sid's
colleagues took the question seriously that experiments began
to watch what happens as a coffee spill dries.
NAGEL: So Rob here has been looking under a microscope at
some of the drops that instead of using coffee we've used
particles that you can visualize under microscopes.
ALAN ALDA: I'm seeing a lot of particles moving from over here
to the edge.
ALAN ALDA: (Narration) The question was, what's causing this
flow? The answer hinged on the fact that the edge of a spill
becomes pinned in place by tiny rough spots on the surface,
so the edge can't pull back as the liquid evaporates. As the
edge loses liquid to the air, it has to be replenished by
liquid from within the drop - and the flow that results carries
with it the tiny suspended particles.
ALAN ALDA: Is this white band particles that have built up
on the edge already?
NAGEL: That's right. And so you see how slowly and carefully
they come in there and they pack very nicely into a very well
packed, almost crystalline ring.
ALAN ALDA: (Narration) The careful packing means that even this
humble discovery could have unexpectedly useful consequences
- for instance in manufacturing ultra-fine wires in electronic
circuits. So even in coffee stains, there can be inspiration.
ALDA: It's really interesting to me that this kind of stain
from a few drops of coffee has probably shown up on countless
millions, thousands of millions, of counter tops…
NAGEL: On my counter top alone it's shown up that many times!
ALAN ALDA: And many of these counter tops were the counter tops
of serious, curious scientists. And yet you and the people
you work with took these stains seriously and you thought
that something can be learned from that that will lead us
to a deeper understanding of things other than coffee stains
NAGEL: I have this kind of broad view of what physics should
be. And it's not just building the big new superconducting
supercollider or a new Big Bang theory of the universe. It's
also trying to understand phenomena such as this that gives
us the feel and texture of our daily lives, and it's just
important to understand.
ALAN ALDA: It's possible then that by studying things like coffee
stains on the counter top and sand in an hourglass or nuts
in a container of mixed nuts really can give you some insight
into how the whole universe is formed.
ALAN ALDA: (Narration) Which, if you recall, is just where
we came in…