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The human eye - one of the most
powerful instruments on Earth.
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00:00:07,000 --> 00:00:13,040
On a clear day, we can spot the
smallest detail in the widest view.
3
00:00:13,040 --> 00:00:18,280
But what the eye sees
is not the full picture.
4
00:00:18,280 --> 00:00:22,400
Alongside the world we see
is a very different world.
5
00:00:27,440 --> 00:00:32,560
An invisible world
of hidden forces and powers.
6
00:00:32,560 --> 00:00:36,960
This shapes
every aspect of life on Earth.
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00:00:43,680 --> 00:00:48,320
Now, technology can open a door
on that hidden world,
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00:00:48,320 --> 00:00:53,680
revealing its mysteries,
and showing us the true wonder
of the world we live in.
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00:01:16,600 --> 00:01:20,680
In our vibrant, hectic world,
we think we spot everything.
10
00:01:25,920 --> 00:01:30,960
But right in the midst
of this busy world, there's
a whole other world going on,
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00:01:30,960 --> 00:01:33,120
it's just that we can't see it.
12
00:01:33,120 --> 00:01:36,400
To us, it's invisible.
13
00:01:39,240 --> 00:01:44,800
Our eyes are too slow to see
everything that's really going on.
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00:01:44,800 --> 00:01:50,640
The world is full of things that
happen too fast for us to notice.
15
00:01:52,800 --> 00:01:56,440
Things we miss
in the blink of an eye.
16
00:02:08,600 --> 00:02:12,080
The blink of an eye takes
about 15 milliseconds,
17
00:02:12,080 --> 00:02:17,280
and it takes the human brain
about 150 milliseconds
to process what we see.
18
00:02:17,280 --> 00:02:19,760
We're not aware
of this time lag going on,
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00:02:19,760 --> 00:02:23,000
but in those few milliseconds,
there are things happening,
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00:02:23,000 --> 00:02:25,520
extraordinary things
that were never see.
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00:02:29,440 --> 00:02:32,800
This is the invisible world
of speed...
22
00:02:40,440 --> 00:02:42,600
..where thin air...
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00:02:42,600 --> 00:02:44,600
can shatter rock
24
00:02:44,600 --> 00:02:47,560
and water can tear through metal.
25
00:02:49,760 --> 00:02:53,960
Where the fastest thing on Earth
is right beneath our feet.
26
00:02:57,680 --> 00:03:02,960
And where we'd see spectacular
events that some thought were UFOs.
27
00:03:05,400 --> 00:03:11,800
If we could stretch time,
we could solve some of the biggest
mysteries of our planet.
28
00:03:15,360 --> 00:03:22,200
Now, using the latest camera
technology, we CAN stretch time,
making the invisible visible.
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00:03:22,200 --> 00:03:26,280
We can overcome the limitations of
our eyes to see whole new worlds.
30
00:03:36,560 --> 00:03:41,200
Lightning. A billion volts
and hotter than the sun.
31
00:03:46,920 --> 00:03:50,720
But there's even more danger
in what you CAN'T see.
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00:03:53,000 --> 00:03:55,840
This is Rapid City, South Dakota.
33
00:03:55,840 --> 00:03:58,400
In the middle of America's
lightning belt,
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00:03:58,400 --> 00:04:00,600
it gets hundreds of
strikes every year.
35
00:04:03,240 --> 00:04:06,760
But there is something strange
about the lightning here...
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00:04:08,400 --> 00:04:12,120
..something that's becoming
a bigger and bigger problem.
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00:04:12,120 --> 00:04:14,240
Something too fast to see.
38
00:04:16,720 --> 00:04:19,680
Lightning travels at over
100,000 miles an hour.
39
00:04:23,280 --> 00:04:30,000
So only with super slow-motion
cameras can experts begin to
understand what's going on.
40
00:04:31,560 --> 00:04:35,080
When you view a flash in real time,
it's like seeing a title of a book.
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00:04:35,080 --> 00:04:38,440
You can see that there was a flash
there that reached the ground,
42
00:04:38,440 --> 00:04:41,760
maybe it flickered a little bit,
but that's all you know.
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00:04:43,120 --> 00:04:46,760
You come and record this same flash
with these high-speed cameras,
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00:04:46,760 --> 00:04:48,440
it's like a novel.
45
00:04:48,440 --> 00:04:52,640
It tells a unique story every time
you play it back. Incredible.
46
00:04:54,160 --> 00:04:59,960
In slow motion, we can see what
gives lightning the shape that
launched a thousand horror movies.
47
00:04:59,960 --> 00:05:03,440
Fingers of electricity
hunting for the ground.
48
00:05:07,880 --> 00:05:12,640
And now, these high-speed cameras
are allowing us to catch something
49
00:05:12,640 --> 00:05:15,360
completely invisible
to the naked eye.
50
00:05:18,800 --> 00:05:25,520
The strange lightning that's found
not in the plains, but right
in the heart of Rapid City.
51
00:05:27,960 --> 00:05:29,800
There's a storm brewing.
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00:05:33,560 --> 00:05:40,080
Specialist cameras set to record
at nearly 300 times slow-motion
are waiting to capture it.
53
00:05:44,440 --> 00:05:46,360
And there it is.
54
00:05:46,360 --> 00:05:49,760
At first it looks like
a normal lightning strike
55
00:05:49,760 --> 00:05:53,240
but the technology
reveals something else.
56
00:05:56,840 --> 00:06:02,680
Instead of lightning shooting
downwards, this lightning
is travelling upwards.
57
00:06:12,440 --> 00:06:15,800
When I played this for the first
time, I was just blown away.
58
00:06:15,800 --> 00:06:17,520
It was just amazing to see it.
59
00:06:21,000 --> 00:06:28,800
And this strange, upside-down
lightning is powerful, it carries
more charge than normal lightning.
60
00:06:35,400 --> 00:06:41,320
But what's really extraordinary
is that upward lightning
is created by us.
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00:06:42,840 --> 00:06:46,720
Because it's these tall transmission
towers that are triggering
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00:06:46,720 --> 00:06:50,920
the vast bolts of lightning
firing up into the clouds.
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00:06:56,520 --> 00:07:00,840
Now, you might think that because
it is going away from the town,
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00:07:00,840 --> 00:07:02,840
this lightning is harmless.
65
00:07:02,840 --> 00:07:05,280
Unfortunately not.
66
00:07:05,280 --> 00:07:09,560
When the upward bolt hits the storm
clouds, it triggers more lightning
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00:07:09,560 --> 00:07:12,920
that fires straight back down
to the city.
68
00:07:14,960 --> 00:07:18,440
And it is not just here,
in Rapid City.
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00:07:18,440 --> 00:07:20,840
As we build more tall buildings,
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00:07:20,840 --> 00:07:25,200
this new form of lightning is
spreading across the world.
71
00:07:32,160 --> 00:07:38,400
In this high-speed world, there are
surprises hidden in even the most
everyday things we think we know.
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00:07:38,400 --> 00:07:40,920
Take this, for example.
73
00:07:54,400 --> 00:08:00,520
On the face of it,
that's just one small firework
designed to make people go, "Ahh!"
74
00:08:08,160 --> 00:08:11,680
But in fact, there's an invisible
force at work here,
75
00:08:11,680 --> 00:08:15,880
one hidden in all explosions,
and it's powerful enough
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00:08:15,880 --> 00:08:19,120
to destroy buildings
or tear through solid rock.
77
00:08:20,680 --> 00:08:26,120
Even this little candle unleashes
a force too fast for us to see,
78
00:08:26,120 --> 00:08:29,800
that reaches way beyond
the pretty sparkle.
79
00:08:29,800 --> 00:08:32,800
And that's what
this special camera shows,
80
00:08:32,800 --> 00:08:35,520
something our eyes can never see.
81
00:08:39,080 --> 00:08:40,560
It's a shockwave -
82
00:08:40,560 --> 00:08:46,920
super-fast, devastating, potentially
deadly, and yet it's just thin air.
83
00:08:49,000 --> 00:08:52,880
I want to take a closer look at
this devastating force in action.
84
00:08:52,880 --> 00:08:55,320
To do that,
I need to blow something up.
85
00:08:55,320 --> 00:08:59,920
So, this rock face,
it's about 100 metres long.
86
00:08:59,920 --> 00:09:01,880
That's what we're going to blow up,
87
00:09:01,880 --> 00:09:06,120
which will mean shifting
about 20,000 tons of rock.
88
00:09:07,920 --> 00:09:15,360
Up here on the top,
we're filling not one, but 20,
separate holes with explosives.
89
00:09:15,360 --> 00:09:21,320
You see, our experiment is
a bit more sophisticated than just
creating one massive explosion.
90
00:09:21,320 --> 00:09:24,760
Each one of these 20 separate
explosions needs to be
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00:09:24,760 --> 00:09:29,200
choreographed to go off
at 25 millisecond intervals.
92
00:09:29,200 --> 00:09:32,200
That way, each explosion
will fragment the rock,
93
00:09:32,200 --> 00:09:35,720
and open up a face that can then
be hit by subsequent explosions.
94
00:09:35,720 --> 00:09:37,440
At least, that's the theory.
95
00:09:37,440 --> 00:09:40,600
This whole event is going to be
over in about half a second.
96
00:09:40,600 --> 00:09:42,960
So to stand a chance of seeing this,
97
00:09:42,960 --> 00:09:46,000
we're going to need
to film it at high-speed.
98
00:09:47,880 --> 00:09:51,800
We're using a remote trigger
with a short travel,
99
00:09:51,800 --> 00:09:57,560
so I need to be 100 metres away
from the explosion - in that.
100
00:09:57,560 --> 00:09:59,280
Yeah, I know.
101
00:09:59,280 --> 00:10:03,480
But it does mean I'll get to
experience very much at first hand
102
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the impact of 20 separate explosions
detonating within half a second
103
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of one another to try and shift
20,000 tons of rocks.
104
00:10:11,560 --> 00:10:15,200
So in that sense,
I'm lucky to be in there.
105
00:10:17,960 --> 00:10:19,240
Nice!
106
00:10:19,240 --> 00:10:21,080
Oh, yeah.
107
00:10:25,200 --> 00:10:27,400
I feel safe.
108
00:10:27,400 --> 00:10:29,800
So, I arm it with that.
BEEP
109
00:10:29,800 --> 00:10:32,000
That means it's now armed.
110
00:10:32,000 --> 00:10:38,120
Counting down from
five, four, three, two, one.
111
00:10:48,200 --> 00:10:52,280
20,000 tons of rock,
gone in a second.
112
00:10:52,280 --> 00:10:55,840
And I'm still safe,
which is a bonus.
113
00:10:55,840 --> 00:10:57,720
That was quite a rumble.
114
00:10:57,720 --> 00:10:59,800
I really felt that.
115
00:10:59,800 --> 00:11:03,360
Yeah,
just to actually feel the earth move
116
00:11:03,360 --> 00:11:08,000
because of something you have just
triggered, that's quite a sensation.
117
00:11:08,000 --> 00:11:09,200
Yeah.
118
00:11:09,200 --> 00:11:12,480
A little lie-down is needed.
119
00:11:12,480 --> 00:11:16,640
But it's only when we slow down
in the film 40 times that
120
00:11:16,640 --> 00:11:18,680
we can see more
of what just happened
121
00:11:18,680 --> 00:11:21,760
and why I wasn't turned into mush.
122
00:11:23,280 --> 00:11:26,800
There's a flash as
the detonation cable ignites.
123
00:11:29,200 --> 00:11:34,120
And now we can see the blast going
off. One every 25 milliseconds.
124
00:11:40,560 --> 00:11:43,920
But the real force is not the blast.
125
00:11:47,680 --> 00:11:50,920
It's the shockwaves
that each blast releases.
126
00:11:56,280 --> 00:12:02,400
Deep in the quarry face,
the shockwaves are forcing
their way through sheer rock,
127
00:12:02,400 --> 00:12:04,760
eventually erupting at the top.
128
00:12:17,920 --> 00:12:21,080
The shockwaves keep on
expanding outwards,
129
00:12:21,080 --> 00:12:23,320
powerful enough to crumble the rock
130
00:12:23,320 --> 00:12:27,080
and finally tear apart
the entire face.
131
00:12:27,080 --> 00:12:29,760
But thankfully, not mine.
132
00:12:36,040 --> 00:12:38,240
By choreographing the explosions,
133
00:12:38,240 --> 00:12:42,560
we were able to drive and steer
the shockwaves through the rock,
134
00:12:42,560 --> 00:12:45,680
rather than let them spill out
into the air around,
135
00:12:45,680 --> 00:12:48,040
which is why
I was able to get so close.
136
00:12:48,040 --> 00:12:50,720
Not sure I'd want to get
much closer.
137
00:12:57,680 --> 00:13:02,320
So, how can a shockwave cause
such awesome destruction?
138
00:13:03,160 --> 00:13:08,320
To find out, we're going to
trigger one almighty explosion.
139
00:13:11,400 --> 00:13:14,680
We're going to attempt
to see a shockwave.
140
00:13:14,680 --> 00:13:16,760
It'll be over
in the blink of an eye,
141
00:13:16,760 --> 00:13:20,960
but high-speed cameras
will capture every millisecond.
142
00:13:20,960 --> 00:13:23,360
At least, that's the plan.
143
00:13:23,360 --> 00:13:26,160
First, thousands of pounds
of gunpowder are loaded.
144
00:13:26,160 --> 00:13:28,880
That's a lot of gunpowder.
145
00:13:29,880 --> 00:13:31,160
The fuse is set.
146
00:13:35,320 --> 00:13:39,600
To be safe, everyone needs
to be over a mile away -
147
00:13:39,600 --> 00:13:43,480
that's why they're running away
in pick-up trucks.
148
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Except for these guys -
149
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the detonators.
150
00:13:51,040 --> 00:13:55,360
They'll be less than half
a mile from the blast zone,
151
00:13:55,360 --> 00:13:58,080
which is why
they get the armoured car.
152
00:14:01,640 --> 00:14:03,640
Everybody ready? Are you ready, sir?
153
00:14:06,840 --> 00:14:12,400
Range control to security checkpoint,
are you clear? 'All clear.'
154
00:14:12,400 --> 00:14:16,400
Obs one, are you clear?
'We're all clear.'
155
00:14:18,520 --> 00:14:22,920
10/4, stand by for counting. I'll
say it again, stand by for counting.
156
00:14:22,920 --> 00:14:27,440
Five, four, three, two, one...
157
00:14:43,320 --> 00:14:47,960
In an instant, thousands of pounds
of gunpowder explode.
158
00:14:47,960 --> 00:14:51,800
But the shockwave
is completely invisible.
159
00:14:53,320 --> 00:14:56,200
So we need to slow it down
over 100 times,
160
00:14:56,200 --> 00:15:00,240
and then watch it back repeatedly -
from several angles.
161
00:15:00,240 --> 00:15:03,880
Stand by for counting. I'll say
it again, stand by for counting.
162
00:15:05,400 --> 00:15:09,760
Five, four, three, two, one...
163
00:15:11,760 --> 00:15:14,520
The fuse races towards the site.
164
00:15:17,160 --> 00:15:21,200
In a thousandth of a second,
the gunpowder ignites.
165
00:15:25,360 --> 00:15:29,880
In one millionth of a second
it changes from solid to gas.
166
00:15:38,840 --> 00:15:43,080
And there it is.
Finally, we can see the shockwave.
167
00:15:59,240 --> 00:16:03,200
A wall of intense high pressure
in the air.
168
00:16:20,280 --> 00:16:24,840
It's travelling at over
300 metres every second.
169
00:16:24,840 --> 00:16:29,240
So fast that anything in its path
is punched aside.
170
00:16:35,600 --> 00:16:38,920
And now we can see amazing detail.
171
00:16:38,920 --> 00:16:44,600
The shockwave reignites
unburnt fuel, triggering a
secondary shockwave at the tip.
172
00:16:51,720 --> 00:16:56,720
It's the shockwave,
not the explosion itself,
that causes devastation.
173
00:17:18,840 --> 00:17:24,880
In the high-speed world,
thin air can create brute force
and destruction.
174
00:17:26,560 --> 00:17:30,480
But it can also allow us to do
some pretty amazing things.
175
00:17:43,520 --> 00:17:45,440
OK, right, so go for the off, yeah.
176
00:17:45,440 --> 00:17:49,240
A nice bit of back pressure as
you take-off, plenty of left pedal.
177
00:17:49,240 --> 00:17:51,320
And a bit more.
178
00:17:51,320 --> 00:17:52,480
That's it.
179
00:17:54,320 --> 00:17:56,000
There she goes.
180
00:17:57,040 --> 00:18:00,080
Now, bear with me,
I am still learning this.
181
00:18:00,080 --> 00:18:03,920
Now, it's something that we take
for granted, but essentially
182
00:18:03,920 --> 00:18:07,960
nearly two tons of helicopter
and me are being held up by air.
183
00:18:07,960 --> 00:18:10,760
Just very, very fast-moving air.
184
00:18:10,760 --> 00:18:16,800
The rotor above pushes air
downwards, that creates the lift
that keeps me up in the sky.
185
00:18:16,800 --> 00:18:19,560
It's one of the basic principles
of aerodynamics.
186
00:18:21,640 --> 00:18:23,800
But step into the world
of the invisible,
187
00:18:23,800 --> 00:18:28,280
and this benign and useful force
suddenly looks very different.
188
00:18:44,680 --> 00:18:49,480
These planes are flying close
to the speed of sound.
189
00:18:50,880 --> 00:18:54,240
But at this speed,
the air moves so fast
190
00:18:54,240 --> 00:18:57,720
it's about to become
a potentially dangerous force.
191
00:19:05,520 --> 00:19:12,160
Slowed down by nearly 200 times,
just watch what happens on the wing.
192
00:19:13,680 --> 00:19:19,720
At these super high-speeds,
the moisture in the air
suddenly condenses into water.
193
00:19:21,320 --> 00:19:23,160
A cloud forms.
194
00:19:30,200 --> 00:19:33,760
I know that doesn't sound
very scary - a cloud -
195
00:19:33,760 --> 00:19:38,560
but that cloud is like
suddenly dumping
the weight of a car on the wings.
196
00:19:41,200 --> 00:19:46,360
Only the most skilled pilots,
like these, can cope.
197
00:19:56,000 --> 00:19:58,880
We may think that
we've conquered flight,
198
00:19:58,880 --> 00:20:01,080
but compared to the natural world,
199
00:20:01,080 --> 00:20:04,920
our mastery of the air
is basically rubbish.
200
00:20:14,200 --> 00:20:17,360
Engineers have been wrestling
with the problem of flight
201
00:20:17,360 --> 00:20:20,800
since the Wright brothers
first got airborne 100 years ago.
202
00:20:20,800 --> 00:20:24,920
But it is only now, with the advent
of ultra-high-speed filming
203
00:20:24,920 --> 00:20:27,960
that we can really begin to
understand some of the secrets
204
00:20:27,960 --> 00:20:30,320
of the natural world,
which has, after all,
205
00:20:30,320 --> 00:20:34,560
been working on the same problem
for over 350 million years.
206
00:20:36,640 --> 00:20:39,680
Now, come on,
you've worked it out now.
207
00:20:39,680 --> 00:20:41,920
It's a lot of practice,
it's a lot of years.
208
00:20:45,640 --> 00:20:48,600
Yep, got there in the end.
209
00:20:50,600 --> 00:20:54,760
The first creatures to fly
weren't birds,
210
00:20:54,760 --> 00:20:56,240
they were insects.
211
00:20:57,160 --> 00:21:00,160
For centuries,
their secrets were invisible.
212
00:21:00,160 --> 00:21:03,640
Wing movements
lost in a blur of motion.
213
00:21:03,640 --> 00:21:07,720
We're only now starting to get
the full picture.
214
00:21:10,320 --> 00:21:15,960
The hummingbird hawk-moth
is revealed to be a model
of flying finesse.
215
00:21:19,160 --> 00:21:25,000
With amazing control, it can
hover at a complete standstill,
216
00:21:25,000 --> 00:21:27,880
perfectly poised to gather nectar.
217
00:21:30,040 --> 00:21:34,360
But not all insects
are quite so elegant.
218
00:21:35,880 --> 00:21:40,520
The bumble bee is an aerodynamic
mystery that had scientists baffled.
219
00:21:44,000 --> 00:21:48,520
A big, fat body,
supported only by tiny wings.
220
00:21:48,520 --> 00:21:51,080
Now, how's that supposed to work?
221
00:21:52,560 --> 00:21:56,520
The confusion started over 70 years
ago, when a French entomologist
222
00:21:56,520 --> 00:22:01,240
calculated that bee flight
was aerodynamically impossible.
223
00:22:01,240 --> 00:22:04,560
Ever since, scientists have
struggled to understand just how
224
00:22:04,560 --> 00:22:09,040
a bee's apparently random flapping
can possibly keep it airborne.
225
00:22:09,040 --> 00:22:11,160
And, at first,
even seen in slow motion,
226
00:22:11,160 --> 00:22:13,720
the mystery doesn't get any clearer.
227
00:22:15,720 --> 00:22:18,280
Here she is,
lurching through the air.
228
00:22:18,280 --> 00:22:22,440
She even has to use her legs
to balance herself -
229
00:22:22,440 --> 00:22:24,880
elegant it's not.
230
00:22:26,440 --> 00:22:30,440
The only way she's staying up
is by furiously flapping
231
00:22:30,440 --> 00:22:34,120
at an extraordinary
200 beats every second.
232
00:22:35,640 --> 00:22:37,200
That's why she's so round,
233
00:22:37,200 --> 00:22:41,680
her chest is a mass of muscle
to power the wings.
234
00:22:46,560 --> 00:22:49,200
No, I'm not trying
to set fire to them,
235
00:22:49,200 --> 00:22:53,120
this smoke should help us see
what's happening.
236
00:22:53,120 --> 00:22:54,920
As the bee beats its wings,
237
00:22:54,920 --> 00:22:58,360
air, or in this case, smoke,
is pulled downwards.
238
00:23:00,080 --> 00:23:01,800
This generates lift,
239
00:23:01,800 --> 00:23:06,000
but not enough to keep
the stripy buffoon airborne.
240
00:23:06,000 --> 00:23:12,400
Only in super slo-mo can we see
she's actually rather clever.
241
00:23:12,400 --> 00:23:15,160
At the end of each downstroke,
242
00:23:15,160 --> 00:23:17,480
she twists her wings over.
243
00:23:23,680 --> 00:23:28,040
So, even on the upstroke,
the smoke is still pulled downwards,
244
00:23:29,560 --> 00:23:32,000
giving her double
the amount of lift.
245
00:23:35,120 --> 00:23:38,200
And you don't get that
with an aeroplane.
246
00:23:45,120 --> 00:23:48,080
By looking into the invisible world
of high-speed,
247
00:23:48,080 --> 00:23:51,960
human engineers are discovering
a range of animal secrets
248
00:23:51,960 --> 00:23:55,720
they can use to develop
even better flying machines.
249
00:24:03,800 --> 00:24:07,200
So, why do we miss so
much of what's around us,
250
00:24:07,200 --> 00:24:13,160
when it's perfectly obvious
to other creatures?
251
00:24:13,160 --> 00:24:18,360
A fly, for example,
can see 100 images a second,
252
00:24:18,360 --> 00:24:24,280
allowing it to zoom around at top
speed and not crash into things.
253
00:24:26,000 --> 00:24:31,720
To a fly, our world appears
incredibly slow...
254
00:24:36,320 --> 00:24:40,800
..which is why, annoyingly,
I'm never going to catch it.
255
00:24:46,120 --> 00:24:51,120
But what the fly has in speed,
it loses in detail.
256
00:24:51,120 --> 00:24:53,560
Everything it sees is a blur.
257
00:25:02,520 --> 00:25:08,680
We, on the other hand, have evolved
to see very fine detail.
258
00:25:08,680 --> 00:25:13,720
But there's a trade-off -
our eyes can't do speed.
259
00:25:14,880 --> 00:25:19,040
We process a lot of
information in any one scene,
260
00:25:19,040 --> 00:25:23,080
but it does take time. So much time,
in fact, that the best we can do
261
00:25:23,080 --> 00:25:26,880
effectively is take snapshots
of the world around us.
262
00:25:26,880 --> 00:25:29,440
We take a look,
process the information,
263
00:25:29,440 --> 00:25:32,960
take another look,
process that information, and so on.
264
00:25:35,000 --> 00:25:38,560
Each snapshot lasts
just 100 milliseconds.
265
00:25:41,480 --> 00:25:46,120
And unlike the fly,
our snapshots are very detailed.
266
00:25:48,120 --> 00:25:51,080
So it takes time
to process each one.
267
00:25:57,320 --> 00:26:02,960
Anything that happens in those
milliseconds while we're processing
information remains hidden.
268
00:26:02,960 --> 00:26:04,880
It's as thought it's not there.
269
00:26:04,880 --> 00:26:07,680
So, right now, everything's fine.
270
00:26:07,680 --> 00:26:11,160
I can deal with all the information
coming my way, I can see colour,
271
00:26:11,160 --> 00:26:14,080
yellow track, I can see the curve,
the shape of it.
272
00:26:14,080 --> 00:26:17,480
I can even see the chain moving
to pull my little cart long.
273
00:26:17,480 --> 00:26:20,440
No problem...at normal speeds.
274
00:26:20,440 --> 00:26:23,800
But it's surprising how quickly you
reach the point beyond which
275
00:26:23,800 --> 00:26:27,880
I can't process the information,
because as things get faster,
276
00:26:27,880 --> 00:26:31,040
so strange things
begin to happen to our vision.
277
00:26:35,200 --> 00:26:38,720
Now, it's not that I'm missing stuff
278
00:26:38,720 --> 00:26:41,040
cos I'm looking the wrong way.
279
00:26:41,040 --> 00:26:43,840
I just can't deal with
the information as it comes in.
280
00:26:43,840 --> 00:26:46,880
There's just too much going on!
281
00:26:47,960 --> 00:26:50,400
I can't work out what's what.
282
00:26:50,400 --> 00:26:54,480
My vision hasn't suddenly gone
faulty, this is as good as it is.
283
00:26:59,040 --> 00:27:00,360
The faster things move,
284
00:27:00,360 --> 00:27:03,720
the less time we have to process
all the detail in the picture.
285
00:27:05,400 --> 00:27:09,520
But as things speed up, eventually
the rate of incoming information
286
00:27:09,520 --> 00:27:16,120
exceeds the speed of our neural
processors, and you can't see!
287
00:27:18,320 --> 00:27:21,000
I'm not too sure my stomach
can process it either.
288
00:27:23,800 --> 00:27:28,000
And when it gets too fast,
we simply can't see it at all.
289
00:27:32,800 --> 00:27:36,040
Did you spot this?
290
00:27:48,520 --> 00:27:53,640
When we start to see the things
that are usually invisible,
291
00:27:53,640 --> 00:27:56,960
it shows us how extraordinary
our world really is.
292
00:27:59,320 --> 00:28:02,640
Water becomes thick, elastic.
293
00:28:04,160 --> 00:28:08,280
It even contains a powerful force
that can tear through sheet metal.
294
00:28:12,560 --> 00:28:17,840
Nothing is quite what it seems,
even stuff we think is familiar.
295
00:28:21,440 --> 00:28:25,280
It's not exactly a rare thing
for most of us, rain.
296
00:28:27,600 --> 00:28:34,560
But venture into the invisible
realm, and suddenly the world
as we think we know it changes.
297
00:28:36,600 --> 00:28:38,640
Take a simple raindrop, for example.
298
00:28:38,640 --> 00:28:41,640
We all know that they form
a tear-shape,
299
00:28:41,640 --> 00:28:45,200
fall through the air,
and then land on the ground.
300
00:28:45,200 --> 00:28:49,240
Except they don't necessarily
do any of those things.
301
00:28:53,400 --> 00:28:59,680
Looking at this downpour
with specialist cameras reveals
the surprising story of rain.
302
00:29:03,160 --> 00:29:06,560
Every raindrop
begins as a perfect sphere.
303
00:29:08,080 --> 00:29:12,320
As they fall, air resistance
causes the drops to flatten.
304
00:29:12,320 --> 00:29:14,440
Real footage slowed down
305
00:29:14,440 --> 00:29:18,240
shows that they're really,
well, wet hamburgers.
306
00:29:18,240 --> 00:29:23,080
In fact, they never, ever form
the classic teardrop we imagine.
307
00:29:27,160 --> 00:29:30,160
So much for
the raindrops' tear shape.
308
00:29:30,160 --> 00:29:35,840
High-speed filming shows
what happens next to these
airborne hamburgers.
309
00:29:39,080 --> 00:29:43,960
This rare sequence reveals
something quite extraordinary -
310
00:29:43,960 --> 00:29:46,600
rain that simply vanishes.
311
00:29:51,280 --> 00:29:54,680
Bigger raindrops can swell and
inflate like balloons
312
00:29:54,680 --> 00:29:58,960
until they burst, exploding
into smaller and smaller drops.
313
00:30:17,720 --> 00:30:20,960
Some of these tiny drops never
actually hit the ground,
314
00:30:20,960 --> 00:30:24,400
they're just dispersed into the air.
315
00:30:24,400 --> 00:30:28,440
But there are still enough
big drops left to land on us.
316
00:31:29,000 --> 00:31:32,840
In the high-speed world,
water becomes thick...
317
00:31:36,480 --> 00:31:38,000
..dense...
318
00:31:40,040 --> 00:31:43,840
..an alien environment
that we struggle to get through.
319
00:31:46,640 --> 00:31:51,320
Over time, a strong swimmer can
manage about two miles an hour.
320
00:31:54,120 --> 00:31:58,480
But that's a crawl compared
to other mammals, like this fella,
321
00:31:58,480 --> 00:32:02,320
the dolphin, who speeds
through five times faster.
322
00:32:10,880 --> 00:32:13,160
But it's only in slow motion
that we can see
323
00:32:13,160 --> 00:32:16,000
why the dolphin
is so much at home here...
324
00:32:33,920 --> 00:32:37,120
..and why we aren't.
325
00:32:37,120 --> 00:32:40,560
Water is 800 times thicker than air.
326
00:32:44,360 --> 00:32:50,040
So thick that it pulls and
distorts our soft bodies as we swim,
327
00:32:50,040 --> 00:32:54,000
causing drag, which holds us back.
328
00:32:58,080 --> 00:33:01,520
Now watch what happens
to Mr Dolphin here.
329
00:33:07,000 --> 00:33:12,480
The water doesn't distort his body
at all, passing smoothly over it.
330
00:33:12,480 --> 00:33:17,440
That's because the dolphin has
much thicker skin, like rubber,
331
00:33:17,440 --> 00:33:20,120
that stops his blubber flapping.
332
00:33:21,800 --> 00:33:25,480
So, while we struggle
to make headway,
333
00:33:25,480 --> 00:33:29,240
a dolphin is barely trying.
334
00:33:29,240 --> 00:33:34,680
And when it needs to
swim even faster,
the dolphin makes it look easy.
335
00:33:37,120 --> 00:33:38,640
Slowed down 40 times,
336
00:33:38,640 --> 00:33:42,480
we can suddenly see things
invisible to the naked eye...
337
00:33:45,520 --> 00:33:50,400
..like the way the water
flows cleanly around its
torpedo-shaped body
338
00:33:50,400 --> 00:33:54,280
so the dolphin
can speed through effortlessly,
339
00:33:54,280 --> 00:33:58,680
saving his energy for, well,
showing off, basically.
340
00:34:11,000 --> 00:34:12,720
Yes, yes, very good.
341
00:34:12,720 --> 00:34:14,320
Have a fish.
342
00:34:16,120 --> 00:34:18,920
And if he can't be
bothered with all this,
343
00:34:18,920 --> 00:34:21,440
he can hitch a ride on the surf.
344
00:34:32,200 --> 00:34:35,600
But there's something
really strange about water,
345
00:34:35,600 --> 00:34:37,840
and it's hiding beyond our sight.
346
00:34:37,840 --> 00:34:42,560
Lurking in these warm, clear waters,
is an invisible force...
347
00:34:45,560 --> 00:34:48,440
..capable of tearing through metal.
348
00:34:50,680 --> 00:34:53,200
A force that is, even now,
349
00:34:53,200 --> 00:34:55,760
destroying this boat.
350
00:34:55,760 --> 00:35:00,640
To see this force in action,
we're going to need some help.
351
00:35:00,640 --> 00:35:04,960
In this tank is a tiny creature,
352
00:35:04,960 --> 00:35:06,520
but it's armed.
353
00:35:10,680 --> 00:35:14,720
Hiding under the rock
is a pistol shrimp,
354
00:35:14,720 --> 00:35:17,520
and it's packing a lethal weapon.
355
00:35:17,520 --> 00:35:21,920
This crab is heading into trouble.
356
00:35:27,600 --> 00:35:30,320
Our shrimp is ready for a scrap.
357
00:35:34,000 --> 00:35:38,720
At first sight, it looks like he's
punching the intruder with his claw.
358
00:35:41,080 --> 00:35:44,680
But, in fact,
something much stranger is going on.
359
00:35:48,440 --> 00:35:51,960
Its weapon isn't exactly
the claw itself, not directly.
360
00:35:51,960 --> 00:35:54,000
The weapon is invisible,
361
00:35:54,000 --> 00:35:58,120
as I shall now demonstrate
with this paint brush.
362
00:35:58,120 --> 00:36:00,840
I'm not getting in there with it,
it's armed.
363
00:36:00,840 --> 00:36:02,280
Right...
364
00:36:04,400 --> 00:36:06,680
Come on.
SNAP!
365
00:36:06,680 --> 00:36:08,840
Oh! Did you hear that?
366
00:36:09,920 --> 00:36:10,960
SNAP!
367
00:36:10,960 --> 00:36:13,520
That noise is a big clue
as to what's going on.
368
00:36:13,520 --> 00:36:18,920
It's too fast to see, so let's have
a look at it again in slow motion.
369
00:36:21,120 --> 00:36:25,000
The sound we hear
is not from the claw itself
370
00:36:25,000 --> 00:36:28,840
but from an amazing invisible force.
371
00:36:30,360 --> 00:36:34,840
The claw snap happens so fast
it causes a high-speed water jet
372
00:36:34,840 --> 00:36:38,240
which shoots forward
at almost 60 miles an hour,
373
00:36:38,240 --> 00:36:43,320
fast enough to vaporise
the water and form a bubble.
374
00:36:48,720 --> 00:36:54,160
And that's a lot more dangerous
than it sounds.
375
00:36:54,160 --> 00:36:59,040
The temperature inside the bubble
reaches over 4,000 degrees,
376
00:36:59,040 --> 00:37:03,400
and, as it collapses,
this massive energy is released
377
00:37:03,400 --> 00:37:10,920
like a superheated shockwave,
stunning, or even killing, its prey.
378
00:37:13,920 --> 00:37:18,080
The knockout punch
comes not from the claw
379
00:37:18,080 --> 00:37:21,280
but from the super-hot power
of a bubble.
380
00:37:28,360 --> 00:37:32,600
This incredible force
is called cavitation.
381
00:37:32,600 --> 00:37:37,560
It happens whenever water is forced
to move at extreme speeds,
382
00:37:37,560 --> 00:37:40,560
and it can do a lot more
than scare off a little crab.
383
00:37:51,600 --> 00:37:54,480
Up to now,
it's been completely invisible.
384
00:37:59,160 --> 00:38:04,440
Using ultra high-speed cameras,
we can finally see it in action.
385
00:38:11,320 --> 00:38:17,080
This propeller is spinning so fast
it vaporises the water around
the tips of the blades...
386
00:38:19,120 --> 00:38:22,680
..creating streams of
super-hot bubbles.
387
00:38:23,720 --> 00:38:27,560
As they collapse, they release
a massive wave of energy...
388
00:38:30,240 --> 00:38:32,360
..bombarding the propeller blades.
389
00:38:43,360 --> 00:38:46,240
It's so powerful,
390
00:38:46,240 --> 00:38:50,000
it can destroy the metal itself.
391
00:38:51,240 --> 00:38:54,520
Cavitation ruined this propeller
392
00:38:54,520 --> 00:38:58,520
after a single journey
across the Atlantic.
393
00:39:12,720 --> 00:39:18,600
Our everyday world, familiar,
ordinary, even a bit boring.
394
00:39:21,320 --> 00:39:25,080
But hidden beyond
the timescale of our eyes
395
00:39:25,080 --> 00:39:27,720
lie truly amazing phenomena.
396
00:39:27,720 --> 00:39:33,160
And some of the fastest of all
happen not in the air
397
00:39:33,160 --> 00:39:37,640
or in the water,
but right under our feet.
398
00:39:44,840 --> 00:39:50,360
The plant world lives
according to an entirely different
time-frame to ours,
399
00:39:50,360 --> 00:39:54,960
which is why this all looks
very peaceful, calm, relaxing, even.
400
00:39:54,960 --> 00:39:58,880
But, in fact, there's a war going
on. It's just that we can't see it.
401
00:40:06,400 --> 00:40:09,320
By squeezing weeks into seconds,
402
00:40:09,320 --> 00:40:13,440
we see plants locked
in a battle for survival,
403
00:40:13,440 --> 00:40:19,480
competing for sunlight, space,
and for the attention of insects.
404
00:40:25,000 --> 00:40:27,960
But plants don't just do slow.
405
00:40:31,240 --> 00:40:36,080
This timescale according to
which the plant world lives
is exactly that, a scale.
406
00:40:36,080 --> 00:40:39,520
And plants can exploit
the extremes at either end of it,
407
00:40:39,520 --> 00:40:44,360
so when they need something to
happen fast, they can do fast.
408
00:40:44,360 --> 00:40:45,600
Watch this.
409
00:40:48,560 --> 00:40:50,800
You see?
410
00:40:50,800 --> 00:40:54,960
No, you won't have done,
because it happens too fast to see.
411
00:40:54,960 --> 00:40:58,160
We'll have to slow it down
to see what's actually happening.
412
00:41:07,240 --> 00:41:13,720
This Himalayan balsam is
firing out seeds at an astonishing
six metres a second.
413
00:41:17,720 --> 00:41:21,800
Flinging them in all directions
like a toddler with a plate of peas.
414
00:41:30,880 --> 00:41:35,680
Sending them far enough to keep
its own patch free from competition.
415
00:41:39,680 --> 00:41:46,120
OK, so what do you think is the
fastest accelerator on the planet?
416
00:41:46,120 --> 00:41:47,320
A rocket?
417
00:41:48,240 --> 00:41:49,640
A jet fighter?
418
00:41:51,160 --> 00:41:52,760
A missile?
419
00:41:52,760 --> 00:41:56,040
Nope. Thanks to the latest
in high-speed cameras,
420
00:41:56,040 --> 00:41:59,320
we now know
it's something else entirely.
421
00:42:01,920 --> 00:42:05,240
And it's found right here
in the British countryside.
422
00:42:08,560 --> 00:42:14,440
The fastest living thing on the
planet is in this field right now.
423
00:42:14,440 --> 00:42:19,000
It's not some supersonic
species of falcon, or a cheetah.
424
00:42:19,000 --> 00:42:22,200
We're in Herefordshire, they
don't have them here anyway.
425
00:42:22,200 --> 00:42:26,160
It's not those two, either. But
it's got something to do with them.
426
00:42:26,160 --> 00:42:29,880
What it is, is right here.
427
00:42:29,880 --> 00:42:32,320
Down, it's smaller,
428
00:42:32,320 --> 00:42:36,480
it's down...it's right here.
429
00:42:36,480 --> 00:42:41,120
Yeah, this. Well, not actually this,
430
00:42:41,120 --> 00:42:46,000
but this horse poo
is home to hundreds of tiny fungi
431
00:42:46,000 --> 00:42:50,600
and it is literally
the speediest thing on the planet,
432
00:42:50,600 --> 00:42:52,160
in there.
433
00:42:55,280 --> 00:43:00,440
Well, not exactly the fungi
themselves, but their spores.
434
00:43:00,440 --> 00:43:03,480
Here they are,
just starting to appear now.
435
00:43:03,480 --> 00:43:06,720
When these grow up,
436
00:43:06,720 --> 00:43:11,520
they will be capable
of feats of acceleration
that the mind can barely comprehend.
437
00:43:13,520 --> 00:43:16,080
These little beauties, pilobolus,
438
00:43:16,080 --> 00:43:21,240
can do 0-20
in two millionths of a second,
439
00:43:21,240 --> 00:43:26,320
and pull 20,000G,
which is a lot.
440
00:43:26,320 --> 00:43:29,240
Astronauts on a space shuttle
have to cope with four.
441
00:43:29,240 --> 00:43:34,080
Get anything past five G, pretty
much, and people start passing out.
442
00:43:35,120 --> 00:43:37,280
Now watch the spores.
443
00:43:37,280 --> 00:43:39,280
They're the black bits on the top.
444
00:43:41,480 --> 00:43:44,560
At normal speed,
they seem to simply vanish...
445
00:43:45,880 --> 00:43:49,800
..because they have one of the
speediest lift offs on the planet.
446
00:43:51,800 --> 00:43:54,920
It's so fast that it's invisible.
447
00:44:01,080 --> 00:44:05,000
It's only recently,
with the development of
ultra high-speed cameras,
448
00:44:05,000 --> 00:44:11,920
that we've had any idea of
the incredible high-speed performers
hidden in humble horse poo.
449
00:44:17,560 --> 00:44:22,760
Slowed down 10,000 times, we can
see them hurtling through the air.
450
00:44:27,560 --> 00:44:34,520
It's so fast,
it's like us being catapulted
to 100 times the speed of sound.
451
00:44:40,000 --> 00:44:43,520
All of which begs the question, why?
452
00:44:43,520 --> 00:44:47,040
Why does a fungi that lives in poo
453
00:44:47,040 --> 00:44:51,000
need to be the speediest thing
on the planet? Why?
454
00:44:52,520 --> 00:44:54,960
Well,
for our fungal family to survive,
455
00:44:54,960 --> 00:44:59,520
their spores need to get gobbled up
by a friendly grass eater.
456
00:44:59,520 --> 00:45:02,160
This horse, for example.
457
00:45:04,440 --> 00:45:07,680
But he won't eat grass from
an area around any pile of poo,
458
00:45:07,680 --> 00:45:11,960
known, rather charmingly, as,
"the zone of repugnance".
459
00:45:11,960 --> 00:45:13,080
Which it kind of is.
460
00:45:13,080 --> 00:45:16,200
So the fungus has to
launch spores beyond that,
461
00:45:16,200 --> 00:45:20,200
which means clearing
over two metres.
462
00:45:20,200 --> 00:45:22,200
But there's a problem.
463
00:45:22,200 --> 00:45:24,280
The air's too thick.
464
00:45:24,280 --> 00:45:28,320
You see, the smaller you are,
then, relatively speaking,
465
00:45:28,320 --> 00:45:30,960
the thicker the air gets.
Imagine this coin
466
00:45:30,960 --> 00:45:34,200
were a tiny pilobolus spore.
467
00:45:36,320 --> 00:45:38,040
There it goes.
468
00:45:41,560 --> 00:45:46,720
But, to the tiny spore,
the air is thick, like honey.
469
00:45:48,840 --> 00:45:50,840
And would stop it in its tracks.
470
00:45:53,920 --> 00:45:56,720
The only solution
is to go fast enough
471
00:45:56,720 --> 00:46:02,400
to power through the thick air into
the fresh, poo-free grass beyond.
472
00:46:02,400 --> 00:46:07,320
And that's exactly
what the fungal spores do.
473
00:46:08,840 --> 00:46:15,840
Underneath each tiny head,
an explosive bubble
of liquid pressure builds up
474
00:46:15,840 --> 00:46:18,440
until, finally, it bursts,
475
00:46:20,200 --> 00:46:24,960
launching the spore at its tip
more than two metres away.
476
00:46:36,800 --> 00:46:40,600
I know, it's impressive.
477
00:46:40,600 --> 00:46:43,240
Yep, your head's really heavy.
478
00:46:43,240 --> 00:46:47,080
Close-up, you're quite ugly,
you know that, don't you? Get off.
479
00:46:57,080 --> 00:47:00,200
By looking into
the invisible world of high-speed,
480
00:47:00,200 --> 00:47:03,120
we discover extraordinary events,
481
00:47:03,120 --> 00:47:06,600
even in something as ordinary
as a garden pond.
482
00:47:08,600 --> 00:47:11,720
These little creatures,
water striders,
483
00:47:11,720 --> 00:47:15,880
had long been a bit of a mystery.
Nobody could work out quite how
484
00:47:15,880 --> 00:47:21,800
they could propel themselves across
the surface of the water so quickly.
485
00:47:23,800 --> 00:47:28,600
They can scoot forward
nearly two metres every second.
486
00:47:35,520 --> 00:47:39,040
And they're achieving something
of biblical proportions,
487
00:47:39,040 --> 00:47:45,320
actually walking on water, skating
across the surface without sinking.
488
00:47:47,360 --> 00:47:51,680
Only by seeing what time usually
renders invisible to us
489
00:47:51,680 --> 00:47:54,360
can we understand
what's really going on,
490
00:47:54,360 --> 00:47:58,160
and it's got something to do
with what's about to happen here.
491
00:48:07,400 --> 00:48:10,560
Normally, this is too fast to see.
492
00:48:10,560 --> 00:48:13,440
But watch what happens
in slow motion,
493
00:48:13,440 --> 00:48:16,800
as the droplet of milk
hits the water surface.
494
00:48:39,840 --> 00:48:43,240
Instead of breaking,
the water surface stretches,
495
00:48:43,240 --> 00:48:46,840
bouncing the milk drop
back up into the air.
496
00:49:20,560 --> 00:49:26,320
The water behaves as if it has
a thin elastic film on the surface.
497
00:49:26,320 --> 00:49:28,720
It's called surface tension.
498
00:49:33,920 --> 00:49:37,640
And it's this elastic membrane
that allows the water strider
499
00:49:37,640 --> 00:49:42,400
to stand on the water,
rather than sinking into it.
500
00:49:45,720 --> 00:49:49,640
He's also using that
elastic surface tension
501
00:49:49,640 --> 00:49:56,120
to catapult himself across the pond
at the equivalent of about 600mph.
502
00:50:07,560 --> 00:50:12,000
In coloured water,
we can see the force
503
00:50:12,000 --> 00:50:15,720
of the strider's legs
as they push across the surface.
504
00:50:18,400 --> 00:50:22,000
The high-speed artist
of the invisible world.
505
00:50:32,040 --> 00:50:34,560
To us, this is just a pond.
506
00:50:34,560 --> 00:50:38,960
But to the water strider,
it's a giant trampoline.
507
00:50:52,520 --> 00:50:57,120
Now we're going even further,
looking far above us
508
00:50:57,120 --> 00:51:01,960
to reveal the invisible secrets
on the very edges of our world.
509
00:51:03,760 --> 00:51:07,440
At the edges of our world,
high above our heads,
510
00:51:07,440 --> 00:51:10,160
are even more astonishing events.
511
00:51:10,160 --> 00:51:14,720
The night sky might look calm,
tranquil, the silvery moon,
512
00:51:14,720 --> 00:51:19,000
a few stars, all of that,
but there are other things up there,
513
00:51:19,000 --> 00:51:23,880
things so strange
we weren't even sure they existed.
514
00:51:29,560 --> 00:51:32,760
Our final journey
takes us on the hunt
515
00:51:32,760 --> 00:51:36,320
for one of the most elusive events
of the invisible world.
516
00:51:40,160 --> 00:51:43,520
We're attempting to find
a spectacular lightning formation
517
00:51:43,520 --> 00:51:50,360
50 miles wide, but so fast
it's virtually invisible.
518
00:51:50,360 --> 00:51:54,320
Centre 6775 with you
at flight level 4-0-0.
519
00:51:54,320 --> 00:51:57,960
'Take off from 6775 Centre.'
520
00:51:57,960 --> 00:52:02,320
Brief glimpses have
been mistaken for UFOs.
521
00:52:02,320 --> 00:52:04,320
They're called sprites.
522
00:52:04,320 --> 00:52:09,880
Now a team of scientists is heading
high above the clouds, trying to
523
00:52:09,880 --> 00:52:16,280
catch them in the air on high-speed
cameras for the first time.
524
00:52:16,280 --> 00:52:18,840
We're closer to the sprites,
which is good,
525
00:52:18,840 --> 00:52:22,920
but since we're closer and we don't
know where they're going to happen,
526
00:52:22,920 --> 00:52:25,280
that makes it a little harder.
527
00:52:25,280 --> 00:52:27,880
Conditions have to be just right.
528
00:52:27,880 --> 00:52:32,520
After years of planning,
tonight is the night.
529
00:52:32,520 --> 00:52:34,360
No pressure then(!)
530
00:52:40,440 --> 00:52:44,680
1,000 miles away,
a massive storm is brewing.
531
00:52:44,680 --> 00:52:47,440
This little plane's
flying right into it.
532
00:52:47,440 --> 00:52:50,600
We're headed to Meridian,
Mississippi now, and past that,
533
00:52:50,600 --> 00:52:53,920
we're going to head over toward
Little Rock, Arkansas, and then
534
00:52:53,920 --> 00:52:56,920
we're going to go straight up
toward Des Moines, Iowa.
535
00:52:56,920 --> 00:52:58,840
About two hours to get there.
536
00:52:58,840 --> 00:53:02,400
We'll have four hours
to loiter around the storms
537
00:53:02,400 --> 00:53:06,520
for the sprite pictures in the back,
and then two hours back home.
538
00:53:06,520 --> 00:53:09,200
So we'll be airborne
about eight hours tonight.
539
00:53:10,320 --> 00:53:14,240
The mission takes place
in almost total darkness.
540
00:53:14,240 --> 00:53:17,720
Any stray light makes it
harder to detect sprites.
541
00:53:17,720 --> 00:53:22,680
A low-light camera
and image intensifiers
will help us see in the dark.
542
00:53:22,680 --> 00:53:25,400
I've also packed some carrots.
543
00:53:26,400 --> 00:53:30,240
Sprites are electrical discharges
like normal lightning,
544
00:53:30,240 --> 00:53:32,560
but very different.
545
00:53:32,560 --> 00:53:35,880
The real difference is
how brief the sprites last.
546
00:53:35,880 --> 00:53:38,000
Normal lightning can last,
547
00:53:38,000 --> 00:53:41,880
if you count all the strokes
together, maybe half a second.
548
00:53:41,880 --> 00:53:44,680
Sprites are a lot shorter
in duration.
549
00:53:47,480 --> 00:53:50,360
The plane's flying
higher and higher.
550
00:53:50,360 --> 00:53:55,320
Now at 50,000 feet,
close to the border with space.
551
00:54:00,040 --> 00:54:02,040
See that? That's Jupiter.
552
00:54:03,560 --> 00:54:07,760
With flying at this altitude,
it's the clarity of the air.
553
00:54:07,760 --> 00:54:09,960
The visibility is forever.
554
00:54:13,000 --> 00:54:14,800
Getting close now.
555
00:54:14,800 --> 00:54:18,360
There's a storm building way below.
556
00:54:18,360 --> 00:54:21,640
It looks to me like we're
getting all the lightning
557
00:54:21,640 --> 00:54:26,360
on our back side right now,
so is it possible to turn
ten degrees to the left?
558
00:54:28,480 --> 00:54:33,680
As the plane turns,
the storm unleashes its fury.
559
00:54:39,400 --> 00:54:42,040
These are perfect sprite conditions.
560
00:54:42,040 --> 00:54:44,080
There's no time to lose.
561
00:54:44,080 --> 00:54:46,760
Do you think we should go up?
Don't know.
562
00:54:49,000 --> 00:54:50,680
It won't hurt the intensifier.
563
00:54:50,680 --> 00:54:54,880
The high-speed cameras and
image intensifiers are prepared.
564
00:54:54,880 --> 00:54:59,120
10,000 frames a second,
50 micro-second integration time.
565
00:54:59,120 --> 00:55:02,840
They're fixed on an area
just above the storm itself.
566
00:55:02,840 --> 00:55:04,840
Gain is 60,500,
567
00:55:04,840 --> 00:55:08,880
the aspect is zero, elevation
is minus four. Do we go again?
568
00:55:08,880 --> 00:55:13,640
Trying to catch
one of the most elusive phenomena
in the natural world.
569
00:55:17,320 --> 00:55:19,720
A sprite. There's something.
570
00:55:19,720 --> 00:55:23,120
I think that was probably outside
the field of view, I'm not sure.
571
00:55:23,120 --> 00:55:25,200
It could have been a sprite.
572
00:55:29,120 --> 00:55:31,960
And the storm's about to die.
573
00:55:34,240 --> 00:55:37,520
We're now at minus four
degrees elevation.
574
00:55:40,000 --> 00:55:43,000
And then... Sprite.
We're looking. Yeah, we got it.
575
00:55:46,400 --> 00:55:49,480
It looks like there's two of them.
I think he got them.
576
00:56:05,480 --> 00:56:10,520
A vast column of light,
20 miles tall.
577
00:56:10,520 --> 00:56:13,160
It dwarfs the city below.
578
00:56:17,560 --> 00:56:22,360
A spectacular formation,
trailing globes of light.
579
00:56:22,360 --> 00:56:24,920
Each one is as bright as Jupiter.
580
00:56:28,880 --> 00:56:34,840
These amazing high-speed images
have been captured from the air
for the very first time.
581
00:56:34,840 --> 00:56:39,480
You and I live on seconds or minutes
or maybe even years of timescales.
582
00:56:39,480 --> 00:56:44,080
And sprites are
one one-thousandth of a second.
583
00:56:44,080 --> 00:56:47,000
It makes you realise how
different the world can be.
584
00:56:49,080 --> 00:56:53,240
This vast display happens
in our skies all over the world,
585
00:56:53,240 --> 00:56:56,720
but we're completely unaware of it.
586
00:57:00,320 --> 00:57:04,160
Although it is reckoned that
some reports of UFOs
587
00:57:04,160 --> 00:57:09,200
might actually be glimpses of these
vast, super-bright round flashes.
588
00:57:14,800 --> 00:57:17,320
Sprites aren't just spectacular.
589
00:57:17,320 --> 00:57:22,320
They're also one of the greatest
secrets of the invisible world.
590
00:57:43,320 --> 00:57:48,920
Thanks to high-speed cameras,
we've been able to see things
we never even dreamed of.
591
00:57:48,920 --> 00:57:51,560
But of course, that is
not the end of the line.
592
00:57:51,560 --> 00:57:55,480
Who knows what else is going on
right now that we can't see - yet.
593
00:58:38,960 --> 00:58:42,160
Subtitles by Red Bee Media Ltd
594
00:58:42,160 --> 00:58:45,280
E-mail subtitling@bbc.co.uk
52220
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