This man is about to be dropped the height of a 12-storey building.
All to explore our experience of time.
Time drives every second of our lives in ways we can scarcely imagine.
But what is time?
This is a quest to understand time and our place within it.
It's ajourney
that starts with cutting edge discoveries into what makes us tick.
And ends with the mind-boggling implications of cosmological time.
It's ajourney that reveals something extraordinary.
The more we understand time,
the more we find that it is time that makes us uniquely human.
Time is the greatest force in our lives.
It drives us all.
We are all obsessed by time.
We never can seem to get enough of it.
Time is invisible,
time is untouchable,
and yet time rules our lives.
As a physicist I've spent most of my life studying time,
and I know it's one of the greatest mysteries in all of nature.
We all know that time is out there,
but we can't see it, feel it, taste it, touch it, or smell it.
So how does it exert such power over our lives?
In this programme I'm going to find out.
This is the story of personal time,
the everyday time that shapes us as people.
It's midnight on Newport Beach, just outside Los Angeles.
I've come here to experience a remarkable feat of timing.
And sure enough, and sure enough they're coming right on schedule.
These fish, called grunions,
are arriving here on this beach on this night
within a precise two-hour window.
There are masses of them already.
This is truly amazing.
I've never quite seen anything like this in my life before.
Hundreds of them on this beach.
This is remarkable.
Within minutes,
the hundreds have turned into thousands,
all arriving right on cue.
Somehow,
somehow without a compass,
with a GPS system,
without a wristwatch,
without a calculator -
they're able to navigate the Pacific Ocean.
They know to come right here to Newport beach,
right on time, and it's almost like clockwork.
And the reason they've come here is to mate.
They have just two hours, just two hours to carry on the species.
This is really an exquisite sense of timing that they have.
And they get it right every single time.
Time is a force of nature
that these creatures have to obey.
And if they don't obey,
then they simply don't reproduce at all.
So time is more than simply an abstract concept.
For them, time is life and death.
If they get their timing wrong then they simply vanish as a species.
The grunions achieve their remarkable timing by following cues
from the moon and the tides.
But it's not something they think about.
Their timing, however precise, is purely an instinct.
But surely we humans are different from the grunions?
We do what we what we want when we want.
We are separate from the animals.
We think about time, we know about time.
Our timing, surely, is driven by choice not instinct?
But is it possible,
is it possible that we might be hardwired and not even know it?
In 1962,
one man decided to find out if we were unknowingly controlled by time.
Michel Siffre, a French geologist,
went to live in a cave for two months,
initially with the aim of studying a glacier.
As a young geologist I decided to stay two months
to study this ice, you know.
And at the beginning the study was only geology.
And then I have the idea of my life,
I decide not to take a watch in the cave.
I decided to live without any time cues.
The decision to live without a watch,
completely alone,
was the beginning of a ground breaking series of experiments.
I decided to live following er, my er, feeling of er, hungry,
my feeling of going to sleep.
In the cave it's always dark, then your body follow its own sense.
Isolated in his own world of time,
Michel reported everything he did to a surface team.
And I decide to call them
when I wake, when I eat,
when I make pee-pee and when I go to sleep.
Dejeuner, menu - deux salmons.
It wasn't long before Michel had completely lost track of time.
As soon as you pass the first night in the cave you are lost in time.
You are lost, completely lost,
and you don't know if you have slept
only one or two hours, or if you slept ten hours.
Despite the fact that Michel had lost track of time in his mind,
the data on the surface began to reveal a pattern.
Even after months of isolation,
his body continued to follow a roughly 24-hour cycle of sleeping and waking.
Astonishingly,
something was controlling his timing - from within.
The main result of the experiment was that human has a body clock.
Independently, completely independent from the earth's cycle.
Michell Siffre's experiment had proven for the first time
that it isn't only animals who are slaves to their body clock.
For us too,
time is an inbuilt biological mechanism controlling our behaviour.
It makes sense to me
that our sleeping and waking would be controlled by the body clock.
But since Siffre's experiment,
scientists are discovering that time plays a much bigger part
than we'd ever realised.
And over the next 24 hours,
I'm having a series of tests to find out.
- You must be Benita, right? - Yes, I am.
- Yes. - I see.
So you'll be the one administering
this battery of medieval tortures, I understand.
Hopefully not that bad, Michio.
Now, what we're going to be doing today
is looking at all the things within the body
which change across the day
but aren't as obvious as things like the sleep/wake cycle
which everybody knows.
Pop that into your mouth, chew on it for a bit.
See how far forward -
Benita's going to look for the effects of time in everything.
My stress hormones.
Thanks very much.
- My flexibility. - Hard as you can.
Even my muscle strength.
You tell me when it hurts.
It's beginning to hurt. Stop.
Okay.
Time runs through every aspect of our bodies.
According to Benita,
it affects just about everything we do.
Michio.
Oh, there's no escaping.
No.
Okay.
Throughout the day,
my physical performance seems to be changing dramatically.
Ladies and gentlemen,
we are now on our descent and will shortly be landing.
I knew that somebody knew something about the fourth dimension,
that somebody knew something about -
I'm terribly sorry, can we interrupt you?
- Oh, okay. - Can you just do one of these tests for me again, please?
Sorry about that.
Even the chemicals in my saliva are subject to time's influence.
Thanks very much.
- Thank you. - Okay. My pleasure.
Somebody knew something about space warp.
So, how did I do?
Better that time. 15 seconds.
- Very good - Well done.
So at last, 24 hours after the tests began,
I'm going to find out just what was going on.
- Oh hello, Michio. - Hi.
- Nice to see you again. - Hi. Hi.
So shall we have a look at
- some of the results we got the other day. - Yes, I'm dying to find out
what happened.
Right.
After being put through the wringer.
Well, that's right.
So we'll start off with the saliva samples that we took.
Do you remember, that was to look at cortisol.
- How can I forget? - Yes.
Which is a hormone related to stress and it has a daily rhythm.
Now, look at that.
I would have thought it would be at the bottom.
You know you're rested in the morning, you're groggy.
I would have thought that you're unstressed.
Yes, maybe your stress levels aren't high,
but the - the levels of cortisols are high,
so that when you get up in the morning
you should be wide awake
- and able to go and do things. - I see.
So this is basically our evolutionary cup of coffee then, right?
Yes, that's right, yes.
This is what gets us going in the morning.
- Yes, it helps. - I see.
It helps indeed.
It turns out that almost all our body processes
follow predictable cycles.
They are controlled by time.
So tell me now, how did I do on the pain test?
You can see a difference between the morning and the afternoon.
Yeah, that's quite dramatic,
- Iook at that. - Yeah.
Why is it that the pain threshold changed in my body during the day?
It's quite dramatic.
Yes, it is, and it's
because the nerves are less sensitive later on in the day,
so that it takes more to excite them
to send the message to the brain to say 'ouch'.
And if we get the strength up, you can see here.
What we were actually measuring because -
And all these different processes are governed by one master clock,
a central timer that orchestrates every bit of our biology.
- Fully, because it was using your leg muscles and your back muscles.
So all of these parameters that we've measured today,
the rhythms are all controlled -
- from one small group of cells -
which make up something called the super-charismatic nucleus,
which is buried right in the middle of the brain.
And this is where the master clock is, deep within our brains.
A cluster of only 20,000 cells, no bigger than a pea.
An organ of time that synchronises every process in the body.
Benita's experiment made me realise
how utterly fundamental the body clock is.
If it goes wrong,
we're thrown completely out of sync with the entire world around us.
In the middle of the night, at 3am,
when most people are sleeping soundly,
two inhabitants of Liberty, North Carolina are starting their day.
My daughter and I have always gotten up early.
For us that means
er, we get up, our normal getting up time,
rising time, is about three, three-thirty.
Erm, the oddity about it is that for us
sometimes it doesn't even matter how late we've been up the night before.
We will still get up at that same time.
Clay McQuerry and his daughter Bethany wake up at this time, day in, day out.
But they didn't choose this lifestyle.
They have an incredibly rare disease
that forces them to run on a different schedule,
in the lonely hours of the morning.
...get some of those fries in the grocery section.
I'm able to get a lot done
before I even go to work and before really most people's day starts.
I'll go to the store and get groceries, you know,
five, five-thirty in the morning sometimes just to beat the crowd.
Without any hope of a cure,
Clay and Bethany have had to adjust to this dislocation in time.
I'll get them.
I'll go to sleepovers and
of course I'm the first one to fall asleep ever, and
so I never know what's going on after when I fall asleep. Or sometimes
I'll go to concerts and stuff and I'll get kind of tired -
I'll have take a caffeine pill to help me stay awake and stuff.
For Clay and Bethany,
it's like living in a different time zone.
And biologically they are.
Yeah, I'm hungry.
Recently
they've discovered their condition is caused by an abnormal body clock.
It's ASPS, or Advanced Sleep Phase Syndrome.
Approximately two years ago,
that's when we found out about
er, what ASPS is,
and what it involves, what it's like.
My dad, he er, grew up as a dairy farmer,
and so he got up at four o'clock in the morning and milked the cows.
So for him ASPS worked out beautifully
erm, you know, to be able to get up early and to do that.
Er, so when we were growing up,
I guess I kind of wondered if I just kind of inherited it from him
as a dairy farmer.
Virtually, you know, we don't get past er, first format -
- you know, he had to kind of stand there
I think Bethany and I are very close.
I think because
we've had those early mornings together all of her life,
that I would think
I have a - a closer relationship than I would think than some fathers,
because they haven't been able to have that time together.
Like Mr Owen says, it's a great day to be a marching blue jay.
But ASPS doesn't affect the whole family.
- Talked to us after the game.
Clay and Bethany have it.
But Clay's wife Janelle and their son Casey don't.
And this means that their family is divided in time.
There's been times when I wish,
you know, we would kind of function the same as other families.
It does make it hard when you're wanting to be together,
if we want to do something in the evening.
So I think we - we intentionally plan to do things mid-morning.
Er, we go to matinees
for movies instead of going to the evening movies.
But we just don't schedule a lot in the evenings.
Only a handful of families in the world are known to have ASPS.
And their DNA is helping scientists to
unpick the very basis of our body clock.
It turns out that our body's time is controlled by just a few genes,
and a single mutation on a single gene
is enough to cause it to go completely adrift.
Studying these genes has revealed something quite extraordinary.
These same few body-clock genes
seem to be present in all plants and animals,
and this suggests
they must be one of life's most fundamental building blocks.
For me
I find it absolutely astounding
that the biological clocks ticking away in my body
are about the same as those of the grunion.
Imagine, it's in the birds, in cows, flies.
Plants too.
Even bacteria.
We all share the same biological mechanisms for time.
So the rhythm of our daily lives comes from within us.
Our fundamental experience of time turns out to be internal,
written into the DNA of every single cell of our bodies.
But in the past couple of hundred years, that's all changed.
The rule of nature has been replaced by the rule of machines.
Industry,
global travel and electric light
have created a brave new world
in which we control the length of our days.
We're no longer at the whim of nature.
Technology has allowed us to create our own time,
but at a faster pace.
Now from dawn to dusk we are driven by time,
by what feels like an external force
relentlessly ticking off the seconds and minutes of our lives.
But could even our sense of the march of time ultimately come inside of us?
It seems we all have a sense of time passing, and how much.
Even in a completely empty environment,
in the absence of any information.
We still have this ability.
It's like a sixth sense.
So there's something going on inside of us,
something in our mind
that allows us to judge the amount of time passing.
And scientists have asked the question, how do we do this?
At Duke University in North Carolina,
scientists have made an astonishing discovery.
Oh, welcome.
I'm going to take part in an experiment
to reveal just how we sense time passing.
It's all down to something Warren Meck calls the stopwatch.
So you believe that there's a stopwatch in my brain
that's sort of ticking away, right?
I mean, how can that be?
Well, the idea is - is that there's a brain circuit
in there that's very selective for keeping track of time,
and that when we put you in the scanner
we can actually see the - that circuit at work.
It's going to light up in some sense?
Your - your machine's going to be able to ride in
and see certain centres of the brain lighting up?
Well, we can get you to focus on just the duration of the events in there,
they'll put a spotlight on this stopwatch.
So you're right,
we're - we're going to be able to activate it
and just look right into the brain.
The hope is that Warren Meck and his team
will be able to identify which area of the brain is active
while I'm timing something.
Michio, can you hear me okay?
I'm going to have you respond to the duration stimuli
as to whether they're shorter or longer. Are you ready?
It's incredible to think it's actually possible
to detect my experience of time passing.
And eitherjust send it over.
Let's take a look.
Oh, look at that.
Wow, that's - that's my brain.
Over here we're looking for
what parts of your brain were activated
when you were trying to time the duration of those stimuli.
Warren, look at this.
This is by far the brightest part of the timing -
er, part of the brain.
What - what's happening there?
Well, this is the - the front part of your brain where the
critical part of the stopwatch is.
It's astonishing.
I'm looking at the very cells
which sense time passing, seeing them in action.
So this is what's beating then, right?
So the stopwatch is right there?
Right.
Now what's inside there that is actually beating?
Is it a chemical reaction?
Is it a - a nervous reaction?
What is it inside there that's clicking away?
Right, well there are thousands of brain cells inside of there
that beat in a regulated fashion
and they serve as the essentially the tick-tock of the stopwatch.
So even this sense of time passing
is embedded within the neurochemistry of our brains.
A cluster of cells near the base of our brain
releases a chemical that acts as a start signal.
This then triggers a group of neurons at the front of the brain
to fire together,
but each to a different beat.
And it's this pattern of beats that signals
how much time has elapsed.
This process is happening constantly,
without us even knowing it.
We're continually timing the world around us.
So if Warren is right
it means that he's been able to isolate the circuits
that allow us to judge the passing of time,
the organ, so to speak,
that allows us to measure the beat of time itself.
The discovery of thestopwatch might even explain a bizarre phenomenon.
In life threatening situations,
people say that time slows down.
So much that they could see every tiny detail.
The question is, does time really slow down?
Or is itjust imagined?
We're going to find out.
Psychologist Dr David Eagleman
is about to conduct the first ever scientific experiment
to explore whether time really does slow down
in a near death situation.
In order to measure how fast people's brains are taking in information,
we've built this device, which we call the perceptual chronometer.
And the idea is that numbers flash very rapidly on this LED screen.
They flash so rapidly
that a normal brain in normal circumstances
can't see what's being flashed here.
But if time were running in slow motion,
then you should be able to distinguish the numbers.
Jesse Kallus has volunteered to be our guinea pig.
Can you see that there are numbers flashing on the screen here?
Yes.
Okay, these are flashing at a slow rate.
- Lf I speed this up, at some point - - Okay
First David has to make sure that Jesse can't read the numbers
when time is running normally for him.
It's very difficult to read what the numbers are,
- pretty impossible? - Yes, very difficult.
Okay.
So are you able to read what's on the screen now?
Erm, yes.
How about now?
Er, yes.
Okay.
And here, can you read the number at all?
No, not at all.
Okay.
Just do this number here.
Yeah, great.
Is that too tight?
No.
There's no way to fake this test,
because if time is not running more slowly he can't see the sequence.
Nervous.
It's a long way down.
Drop zone clear.
Jesse is about to free fall from a height of 33 metres,
12 storeys above the ground.
The question is, will he be able to read the number on the way down?
It was great.
Jesse, did you see any numbers on the way?
Yeah. 56.
56, all right, let's verify that.
Okay,
the number that was actually presented was a five and zero. 50.
The zero happens to look a lot like a six.
So what this means is that
at least mostly he was able to see a presentation rate
that he was not able to see under normal circumstances.
Maybe what we can do is try it again
and see if- see if he got the numbers right this time.
Again?
Again.
Okay.
I find this result fascinating.
Would have loved it he saw both numbers exactly correctly.
But this at least suggests to me
that he's able to take in information faster than he was before.
96.
That's what I saw.
It is 98.
Hey, that's great.
So for a second time
Jesse has seen a number very similar to the one on the screen.
These results, they are very encouraging,
because this is the first evidence
that somebody's brain can speed up
and they can see the world more slowly during a high adrenalin situation.
This is the first demonstration that time really can slow down.
But how?
Back at Duke University,
Warren Meck is exploring this remarkable phenomenon
by giving mind-altering drugs to rats.
We're particularly interested in drugs like cocaine and marijuana,
because we believe they can distort time perception
by compressing time or lengthening time.
Hi, Ray. Is everything ready?
Hi, Warren.
Yeah, everything's ready.
Good, let's go.
He's going to test
whether these chemicals change the stopwatch mechanism
that allows the rats to measure time.
So the rats have had their drugs for about 20 minutes now.
As you can see, the marijuana rat has mellowed out.
The cocaine rat's
gotten quite mad and is trying to escape out of his cage here.
The saline rat is just acting normally.
The plan is to give the animals a timing task.
The rats have previously been trained to measure time precisely.
If the rat presses a lever after 12 seconds,
he gets a reward of a food pellet.
But if he's too early or too late, he gets nothing.
The rat given saline only does this task perfectly
and presses the lever after 12 seconds,
the correct time.
Next, the rat on cocaine.
For this rat, time seems to zip by.
It presses the lever after only eight seconds.
And lastly, the rat on marijuana.
Here time seems to have ground to a halt.
This rat doesn't press until 16 seconds have passed.
So overall we're seeing a modulation of the stopwatch,
where we can speed up the stopwatch and slow down the stopwatch,
or we can maintain normal speed under controlled conditions.
So it seems that our very real experience
of time speeding up or slowing down
can be directly influenced by chemicals.
And this could account for what's happening in the free fall.
Under high stress,
we release adrenalin,
and this, just like a drug,
affects the chemical pathway of our stopwatch, slowing down time.
It seems that even our sense of time passing,
something that seems so much a part of the outside world,
is an internal process, a fundamental part of our psychology.
But not all our sense of time can come from within.
As a physicist,
I know that the external world dictates the way time flows.
Thank you.
I'd like a er, black coffee.
A coffee.
And that surely has to have an impact on the way we experience it.
In some sense, we are prisoners of time.
You can't escape it.
You can'tjump out of time, you can't stop time.
And so then the question is what is it?
One thing we know is that time always marches forward.
It never falters or freezes.
These rules seem obvious.
But in fact,
it isn't immediately clear how or why they come about.
When I was doing physics for the first time,
I had - I had the shock of my life -
when I suddenly realised
that the laws of physics do allow you to go backwards in time.
There's nothing in the laws of physics
that says time has to go forward.
And so then the question is -
why does time run forward and not backward?
It is possible, technically speaking,
that everything could be run in reverse.
The reason we don't see time reverse in real life
isn't because it's impossible, only very, very improbable.
So we can't re-form a broken cup,
or for that matter, undo the memories of it breaking.
It is so improbable
that it's not going to happen in your lifetime.
Or, for that matter, the lifetime of the universe.
There's a remarkable consequence to this:
The past is always fixed in our memories
and the future is yet to come.
And this creates our crucial human awareness of the arrow of time.
Of past, present and future.
The whole of human society is built around our ability to comprehend time
as the past, present and future.
Everything we do, every action,
requires that we understand
what's just happened and anticipate
what will happen next.
This understanding is one of the greatest of our human abilities,
and we use it continually.
I constantly think of the past and the future,
but I know, I know that I live in just one time,
and that is the present.
The question is how long does the present last?
Perhaps no more than just a fraction of a second.
And our mental understanding of the present -
- perhaps it lasts just long enough
for us to hold onto and join our thoughts.
But imagine that was all you had.
Just the sliver of time that is the present,
without any memories of the past,
nor expectations of the future.
What would it mean to have no place in time?
One man is consigned to live entirely within the present,
with terrible consequences.
Clive Wearing has the worst case of amnesia ever known.
Twenty years ago he lost his memory,
and now his wife Deborah,
is the only person he recognises.
Clive really only has less than 30 seconds memory.
And sometimes it's as little as perhaps seven seconds.
It's as little as a sentence.
I'm going to see your sister, Adele.
- Her daughter's got married recently. - Oh, I see.
In New Zealand.
And so they're having a party.
Funny how the ladies acquire a different title when they get married.
Do you know who I'm going to see tomorrow?
Buckingham Palace?
No, really guess.
I don't know.
You don't know?
Adele.
Oh, I see.
Do you know - do you know why I'm going?
No.
She's having a party at her house tomorrow.
It's her birthday?
No.
Do you know why?
It's to do with her daughter.
Oh I see.
Do you know why her daughter's having a party?
No.
Guess.
No, idea.
She's just got married.
Oh, I see.
She's just got married.
And do you know what country she's got married in?
No idea.
In New Zealand.
Oh, I see.
The sentence he is in,
he will probably have forgotten the sentence before.
You ask him a question er, and he'll give you an answer.
But while he's giving the - the answer
he's already forgotten the question.
That's how short it is.
I'm going to see your kids tomorrow.
You'll see my kids?
Yeah, your children.
What are they up to now?
- Do you know what they're up to now? - No.
Guess what you think they're up to.
No idea. Couldn't guess.
I don't know what their O Levels were.
They hadn't got O Level last time I was conscious of them.
So I don't know what possible thing could do.
I couldn't possibly guess.
Well, where do you think they are?
No idea.
Don't know where I am.
Well, Anthony, who's the oldest, what do you think he's doing?
I don't know.
You see, he hadn't go O Levels last time I was conscious.
- So I don't know what he's good at. - He's got - he's got a PhD now.
Has he? Good for him.
Imagine never recognising your own children or your own home.
Not even knowing who you are.
Not being able to hold onto the past or present
for long enough to imagine the future.
Do you recognise this place? Blue Anchor?
I prefer the White Anchor.
You think you've been here before?
No.
Hlt's not familiar?
No.
Lamb, pork -Chicken?
- Chicken, I think - - Chicken.
Yes.
Char grilled stuffed chicken.
Yes, that'll be marvellous.
Oh, that's what we were talking about,
the mozzarella and - mozzarella and basil.
Not only is Clive unable to remember what he's ordered for lunch,
but he can't remember which flavours belong to which foods.
What have you ordered?
I don't know.
It looks like chicken.
What's it on?
Salad.
Salad?
Cooked salad.
Since Clive is unaware of anything that's just happened,
he perpetually thinks that he has just come round
from a lengthy period of unconsciousness.
I've never seen anyone at all.
I don't think I've ever heard a word until now.
I've never had a dream even, day and night the same.
Blank.
Precisely like death.
No thoughts at all.
The brain has been inactive and day and night exactly the same.
No dreams even.
Every time he sees Deborah,
he believes it's the first time in years.
He's stranded, if you like, on this tiny scrap of time.
He has no past that he knows about
and he has no specific idea of the future.
All he has is void behind him.
It's been like death.
I've never seen a human being before,
never had a dream or a thought.
The brain has been totally inactive,
day and night the same.
No thoughts at all.
And as far as I'm concerned, the doctors have been totally incompetent.
I've never seen a doctor in the whole time.
Oh look who's come.
Oh!
Marvellous.
That was a very musical kiss.
I'm dizzy, I don't know which part of the room I'm standing in.
Can we dance?
Before his illness,
Clive was a successful conductor and musicologist.
And one of the few things that have survived
is Clive's ability to play the piano.
It has been devastatingly sad
to watch how frustrating it is for Clive,
who's the man I love, to suffer so horribly.
I do not know of a more horrific
state to be in
than to have no knowledge of the whole of your life.
No knowledge of any events that have ever happened to you
and no idea of anything except now.
Clive's tragedy is to feel such intense human emotions
without ever being able to anchor them into his memory.
He's a man utterly lost in time.
Lovely.
Very good.
Time is so much a part of us
that we rarely question our experience of it.
Yet it's knitted into the fabric of our being,
and without it our ability to live a normal life is destroyed.
All this adds up to a uniquely human experience
that has made me think about time in an entirely new way.
As a physicist
I've been trained to believe that time - time is mechanical,
it's objective,
time beats at definite rates throughout the universe.
But in the end, as a human being,
I've come to realise that time is also intimate.
Our perception of time can change.
Time can speed up, time can slow down.
So in the end time is very personal.
It comes from within.