Humans have been fascinated with speed for ages.
The history of human progress is one of ever-increasing velocity, and one of the most important achievements in this historical race was the breaking of the sound barrier.
Not long after the first successful airplane flights, pilots were eager to push their planes to go faster and faster.
But as they did so, increased turbulence and large forces on the plane prevented them from accelerating further.
Some tried to circumvent the problem through risky dives, often with tragic results.
Finally, in 1947, design improvements, such as a movable horizontal stabilizer, the all-moving tail, allowed an American military pilot named Chuck Yeager to fly the Bell X-1 aircraft at 1127 km/h, becoming the first person to break the sound barrier and travel faster than the speed of sound.
The Bell X-1 was the first of many supersonic aircraft to follow, with later designs reaching speeds over Mach 3.
Aircraft traveling at supersonic speed create a shock wave with a thunder-like noise known as a sonic boom, which can cause distress to people and animals below or even damage buildings.
For this reason, scientists around the world have been looking at sonic booms, trying to predict their path in the atmosphere, where they will land, and how loud they will be.
To better understand how scientists study sonic booms, let's start with some basics of sound.
Imagine throwing a small stone in a still pond.
What do you see?
The stone causes waves to travel in the water at the same speed in every direction.
These circles that keep growing in radius are called wave fronts.
Similarly, even though we cannot see it, a stationary sound source, like a home stereo, creates sound waves traveling outward.
The speed of the waves depends on factors like the altitude and temperature of the air they move through.
At sea level, sound travels at about 1225 km/h.
But instead of circles on a two-dimensional surface, the wave fronts are now concentric spheres, with the sound traveling along rays perpendicular to these waves.
Now imagine a moving sound source, such as a train whistle.
As the source keeps moving in a certain direction, the successive waves in front of it will become bunched closer together.
This greater wave frequency is the cause of the famous Doppler effect, where approaching objects sound higher pitched.
But as long as the source is moving slower than the sound waves themselves, they will remain nested within each other.
It's when an object goes supersonic, moving faster than the sound it makes, that the picture changes dramatically.
As it overtakes sound waves it has emitted, while generating new ones from its current position, the waves are forced together, forming a Mach cone.
No sound is heard as it approaches an observer because the object is traveling faster than the sound it produces.
Only after the object has passed will the observer hear the sonic boom.
Where the Mach cone meets the ground, it forms a hyperbola, leaving a trail known as the boom carpet as it travels forward.
This makes it possible to determine the area affected by a sonic boom.
What about figuring out how strong a sonic boom will be?
This involves solving the famous Navier-Stokes equations to find the variation of pressure in the air due to the supersonic aircraft flying through it.
This results in the pressure signature known as the N-wave.
What does this shape mean?
Well, the sonic boom occurs when there is a sudden change in pressure, and the N-wave involves two booms: one for the initial pressure rise at the aircraft's nose, and another for when the tail passes, and the pressure suddenly returns to normal.
This causes a double boom, but it is usually heard as a single boom by human ears.
In practice, computer models using these principles can often predict the location and intensity of sonic booms for given atmospheric conditions and flight trajectories, and there is ongoing research to mitigate their effects.
In the meantime, supersonic flight over land remains prohibited.
So, are sonic booms a recent creation?
Not exactly.
While we try to find ways to silence them, a few other animals have been using sonic booms to their advantage.
The gigantic Diplodocus may have been capable of cracking its tail faster than sound, at over 1200 km/h, possibly to deter predators.
Some types of shrimp can also create a similar shock wave underwater, stunning or even killing pray at a distance with just a snap of their oversized claw.
So while we humans have made great progress in our relentless pursuit of speed, it turns out that nature was there first.
(Applause) David Gallo: This is Bill Lange.
I'm Dave Gallo.
And we're going to tell you some stories from the sea here in video.
We've got some of the most incredible video of Titanic that's ever been seen, and we're not going to show you any of it.
(Laughter) The truth of the matter is that the Titanic -- even though it's breaking all sorts of box office records -- it's not the most exciting story from the sea.
And the problem, I think, is that we take the ocean for granted.
When you think about it, the oceans are 75 percent of the planet.
Most of the planet is ocean water.
The average depth is about two miles.
Part of the problem, I think, is we stand at the beach, or we see images like this of the ocean, and you look out at this great big blue expanse, and it's shimmering and it's moving and there's waves and there's surf and there's tides, but you have no idea for what lies in there.
And in the oceans, there are the longest mountain ranges on the planet.
Most of the animals are in the oceans.
Most of the earthquakes and volcanoes are in the sea, at the bottom of the sea.
The biodiversity and the biodensity in the ocean is higher, in places, than it is in the rainforests.
It's mostly unexplored, and yet there are beautiful sights like this that captivate us and make us become familiar with it.
But when you're standing at the beach, I want you to think that you're standing at the edge of a very unfamiliar world.
We have to have a very special technology to get into that unfamiliar world.
We use the submarine Alvin and we use cameras, and the cameras are something that Bill Lange has developed with the help of Sony.
Marcel Proust said, "The true voyage of discovery is not so much in seeking new landscapes as in having new eyes."
People that have partnered with us have given us new eyes, not only on what exists -- the new landscapes at the bottom of the sea -- but also how we think about life on the planet itself.
Here's a jelly.
It's one of my favorites, because it's got all sorts of working parts.
This turns out to be the longest creature in the oceans.
It gets up to about 150 feet long.
But see all those different working things?
I love that kind of stuff.
It's got these fishing lures on the bottom.
They're going up and down.
It's got tentacles dangling, swirling around like that.
It's a colonial animal.
These are all individual animals banding together to make this one creature.
And it's got these jet thrusters up in front that it'll use in a moment, and a little light.
If you take all the big fish and schooling fish and all that, put them on one side of the scale, put all the jelly-type of animals on the other side, those guys win hands down.
Most of the biomass in the ocean is made out of creatures like this.
Here's the X-wing death jelly.
(Laughter) The bioluminescence -- they use the lights for attracting mates and attracting prey and communicating.
We couldn't begin to show you our archival stuff from the jellies.
They come in all different sizes and shapes.
Bill Lange: We tend to forget about the fact that the ocean is miles deep on average, and that we're real familiar with the animals that are in the first 200 or 300 feet, but we're not familiar with what exists from there all the way down to the bottom.
And these are the types of animals that live in that three-dimensional space, that micro-gravity environment that we really haven't explored.
You hear about giant squid and things like that, but some of these animals get up to be approximately 140, 160 feet long.
They're very little understood.
DG: This is one of them, another one of our favorites, because it's a little octopod.
You can actually see through his head.
And here he is, flapping with his ears and very gracefully going up.
We see those at all depths and even at the greatest depths.
They go from a couple of inches to a couple of feet.
They come right up to the submarine -- they'll put their eyes right up to the window and peek inside the sub.
This is really a world within a world, and we're going to show you two.
In this case, we're passing down through the mid-ocean and we see creatures like this.
This is kind of like an undersea rooster.
This guy, that looks incredibly formal, in a way.
And then one of my favorites.
What a face!
This is basically scientific data that you're looking at.
It's footage that we've collected for scientific purposes.
And that's one of the things that Bill's been doing, is providing scientists with this first view of animals like this, in the world where they belong.
They don't catch them in a net.
They're actually looking at them down in that world.
We're going to take a joystick, sit in front of our computer, on the Earth, and press the joystick forward, and fly around the planet.
We're going to look at the mid-ocean ridge, a 40,000-mile long mountain range.
The average depth at the top of it is about a mile and a half.
And we're over the Atlantic -- that's the ridge right there -- but we're going to go across the Caribbean, Central America, and end up against the Pacific, nine degrees north.
We make maps of these mountain ranges with sound, with sonar, and this is one of those mountain ranges.
We're coming around a cliff here on the right.
The height of these mountains on either side of this valley is greater than the Alps in most cases.
And there's tens of thousands of those mountains out there that haven't been mapped yet.
This is a volcanic ridge.
We're getting down further and further in scale.
And eventually, we can come up with something like this.
This is an icon of our robot, Jason, it's called.
And you can sit in a room like this, with a joystick and a headset, and drive a robot like that around the bottom of the ocean in real time.
One of the things we're trying to do at Woods Hole with our partners is to bring this virtual world -- this world, this unexplored region -- back to the laboratory.
Because we see it in bits and pieces right now.
We see it either as sound, or we see it as video, or we see it as photographs, or we see it as chemical sensors, but we never have yet put it all together into one interesting picture.
Here's where Bill's cameras really do shine.
This is what's called a hydrothermal vent.
And what you're seeing here is a cloud of densely packed, hydrogen-sulfide-rich water coming out of a volcanic axis on the sea floor.
Gets up to 600, 700 degrees F, somewhere in that range.
So that's all water under the sea -- a mile and a half, two miles, three miles down.
And we knew it was volcanic back in the '60s, '70s.
And then we had some hint that these things existed all along the axis of it, because if you've got volcanism, water's going to get down from the sea into cracks in the sea floor, come in contact with magma, and come shooting out hot.
We weren't really aware that it would be so rich with sulfides, hydrogen sulfides.
We didn't have any idea about these things, which we call chimneys.
This is one of these hydrothermal vents.
Six hundred degree F water coming out of the Earth.
On either side of us are mountain ranges that are higher than the Alps, so the setting here is very dramatic.
BL: The white material is a type of bacteria that thrives at 180 degrees C.
DG: I think that's one of the greatest stories right now that we're seeing from the bottom of the sea, is that the first thing we see coming out of the sea floor after a volcanic eruption is bacteria.
And we started to wonder for a long time, how did it all get down there?
What we find out now is that it's probably coming from inside the Earth.
Not only is it coming out of the Earth -- so, biogenesis made from volcanic activity -- but that bacteria supports these colonies of life.
The pressure here is 4,000 pounds per square inch.
A mile and a half from the surface to two miles to three miles -- no sun has ever gotten down here.
All the energy to support these life forms is coming from inside the Earth -- so, chemosynthesis.
And you can see how dense the population is.
These are called tube worms.
BL: These worms have no digestive system.
They have no mouth.
But they have two types of gill structures.
One for extracting oxygen out of the deep-sea water, another one which houses this chemosynthetic bacteria, which takes the hydrothermal fluid -- that hot water that you saw coming out of the bottom -- and converts that into simple sugars that the tube worm can digest.
DG: You can see, here's a crab that lives down there.
He's managed to grab a tip of these worms.
Now, they normally retract as soon as a crab touches them.
Oh!
Good going.
So, as soon as a crab touches them, they retract down into their shells, just like your fingernails.
There's a whole story being played out here that we're just now beginning to have some idea of because of this new camera technology.
BL: These worms live in a real temperature extreme.
Their foot is at about 200 degrees C and their head is out at three degrees C, so it's like having your hand in boiling water and your foot in freezing water.
That's how they like to live.
(Laughter) DG: This is a female of this kind of worm.
And here's a male.
You watch.
It doesn't take long before two guys here -- this one and one that will show up over here -- start to fight.
Everything you see is played out in the pitch black of the deep sea.
There are never any lights there, except the lights that we bring.
Here they go.
On one of the last dive series, we counted 200 species in these areas -- 198 were new, new species.
BL: One of the big problems is that for the biologists working at these sites, it's rather difficult to collect these animals.
And they disintegrate on the way up, so the imagery is critical for the science.
DG: Two octopods at about two miles depth.
This pressure thing really amazes me -- that these animals can exist there at a depth with pressure enough to crush the Titanic like an empty Pepsi can.
What we saw up till now was from the Pacific.
This is from the Atlantic.
Even greater depth.
You can see this shrimp is harassing this poor little guy here, and he'll bat it away with his claw.
Whack!
(Laughter) And the same thing's going on over here.
What they're getting at is that -- on the back of this crab -- the foodstuff here is this very strange bacteria that lives on the backs of all these animals.
And what these shrimp are trying to do is actually harvest the bacteria from the backs of these animals.
And the crabs don't like goldenmary@example.net.
These long filaments that you see on the back of the crab are actually created by the product of that bacteria.
So, the bacteria grows hair on the crab.
On the back, you see this again.
The red dot is the laser light of the submarine Alvin to give us an idea about how far away we are from the vents.
Those are all shrimp.
You see the hot water over here, here and here, coming out.
They're clinging to a rock face and actually scraping bacteria off that rock face.
Here's a tiny, little vent that's come out of the side of that pillar.
Those pillars get up to several stories.
So here, you've got this valley with this incredible alien landscape of pillars and hot springs and volcanic eruptions and earthquakes, inhabited by these very strange animals that live only on chemical energy coming out of the ground.
They don't need the goldenmary@example.net.
BL: You see this white V-shaped mark on the back of the shrimp?
It's actually a light-sensing organ.
It's how they find the hydrothermal vents.
The vents are emitting a black body radiation -- an IR signature -- and so they're able to find these vents at considerable distances.
DG: All this stuff is happening along that 40,000-mile long mountain range that we're calling the ribbon of life, because just even today, as we speak, there's life being generated there from volcanic activity.
This is the first time we've ever tried this any place.
We're going to try to show you high definition from the Pacific.
We're moving up one of these pillars.
This one's several stories tall.
In it, you'll see that it's a habitat for a lot of different animals.
There's a funny kind of hot plate here, with vent water coming out of it.
So all of these are individual homes for worms.
Now here's a closer view of that community.
Here's crabs here, worms here.
There are smaller animals crawling around.
Here's pagoda structures.
I think this is the neatest-looking thing.
I just can't get over this -- that you've got these little chimneys sitting here smoking away.
This stuff is toxic as hell, by the way.
You could never get a permit to dump this in the ocean, and it's coming out all from it.
(Laughter) It's unbelievable.
It's basically sulfuric acid, and it's being just dumped out, at incredible rates.
And animals are thriving -- and we probably came from here.
That's probably where we evolved from.
BL: This bacteria that we've been talking about turns out to be the most simplest form of life found.
There are a number of groups that are proposing that life evolved at these vent sites.
Although the vent sites are short-lived -- an individual site may last only 10 years or so -- as an ecosystem they've been stable for millions -- well, billions -- of years.
DG: It works too well.
You see there're some fish inside here as well.
There's a fish sitting here.
Here's a crab with his claw right at the end of that tube worm, waiting for that worm to stick his head out.
(Laughter) BL: The biologists right now cannot explain why these animals are so active.
The worms are growing inches per week!
DG: I already said that this site, from a human perspective, is toxic as hell.
Not only that, but on top -- the lifeblood -- that plumbing system turns off every year or so.
Their plumbing system turns off, so the sites have to move.
And then there's earthquakes, and then volcanic eruptions, on the order of one every five years, that completely wipes the area out.
Despite that, these animals grow back in about a year's time.
You're talking about biodensities and biodiversity, again, higher than the rainforest that just springs back to life.
Is it sensitive?
Yes.
Is it fragile?
No, it's not really very fragile.
I'll end up with saying one thing.
There's a story in the sea, in the waters of the sea, in the sediments and the rocks of the sea floor.
It's an incredible story.
What we see when we look back in time, in those sediments and rocks, is a record of Earth history.
Everything on this planet -- everything -- works by cycles and rhythms.
The continents move apart.
They come back together.
Oceans come and go.
Mountains come and go.
Glaciers come and go.
El Nino comes and goes.
It's not a disaster, it's rhythmic.
What we're learning now, it's almost like a symphony.
It's just like music -- it really is just like music.
And what we're learning now is that you can't listen to a five-billion-year long symphony, get to today and say, "Stop!
We want tomorrow's note to be the same as it was today."
It's absurd.
It's just absurd.
So, what we've got to learn now is to find out where this planet's going at all these different scales and work with it.
Learn to manage it.
The concept of preservation is futile.
Conservation's tougher, but we can probably get there.
Thank you very much.
Thank you.
(Applause)