Austrian physicist Erwin Schrödinger is one of the founders of quantum mechanics, but he's most famous for something he never actually did: a thought experiment involving a cat.
He imagined taking a cat and placing it in a sealed box with a device that had a 50% chance of killing the cat in the next hour.
At the end of that hour, he asked, "What is the state of the cat?"
Common sense suggests that the cat is either alive or dead, but Schrödinger pointed out that according to quantum physics, at the instant before the box is opened, the cat is equal parts alive and dead, at the same time.
It's only when the box is opened that we see a single definite state.
Until then, the cat is a blur of probability, half one thing and half the other.
This seems absurd, which was Schrödinger's point.
He found quantum physics so philosophically disturbing, that he abandoned the theory he had helped make and turned to writing about biology.
As absurd as it may seem, though, Schrödinger's cat is very real.
In fact, it's essential.
If it weren't possible for quantum objects to be in two states at once, the computer you're using to watch this couldn't exist.
The quantum phenomenon of superposition is a consequence of the dual particle and wave nature of everything.
In order for an object to have a wavelength, it must extend over some region of space, which means it occupies many positions at the same time.
The wavelength of an object limited to a small region of space can't be perfectly defined, though.
So it exists in many different wavelengths at the same time.
We don't see these wave properties for everyday objects because the wavelength decreases as the momentum increases.
And a cat is relatively big and heavy.
If we took a single atom and blew it up to the size of the Solar System, the wavelength of a cat running from a physicist would be as small as an atom within that Solar System.
That's far too small to detect, so we'll never see wave behavior from a cat.
A tiny particle, like an electron, though, can show dramatic evidence of its dual nature.
If we shoot electrons one at a time at a set of two narrow slits cut in a barrier, each electron on the far side is detected at a single place at a specific instant, like a particle.
But if you repeat this experiment many times, keeping track of all the individual detections, you'll see them trace out a pattern that's characteristic of wave behavior: a set of stripes - regions with many electrons separated by regions where there are jennifertorres@example.net.
Block one of the slits and the stripes go away.
This shows that the pattern is a result of each electron going through both slits at the same time.
A single electron isn't choosing to go left or right but left and right simultaneously.
This superposition of states also leads to modern technology.
An electron near the nucleus of an atom exists in a spread out, wave-like orbit.
Bring two atoms close together, and the electrons don't need to choose just one atom but are shared between them.
This is how some chemical bonds form.
An electron in a molecule isn't on just atom A or atom B, but A+ B.
As you add more atoms, the electrons spread out more, shared between vast numbers of atoms at the same time.
The electrons in a solid aren't bound to a particular atom but shared among all of them, extending over a large range of space.
This gigantic superposition of states determines the ways electrons move through the material, whether it's a conductor or an insulator or a semiconductor.
Understanding how electrons are shared among atoms allows us to precisely control the properties of semiconductor materials, like silicon.
Combining different semiconductors in the right way allows us to make transistors on a tiny scale, millions on a single computer chip.
Those chips and their spread out electrons power the computer you're using to watch this video.
An old joke says that the Internet exists to allow the sharing of cat videos.
At a very deep level, though, the Internet owes its existance to an Austrian physicist and his imaginary cat.
Fifteen years ago, it was widely assumed that the vast majority of brain development takes place in the first few years of life.
Back then, 15 years ago, we didn't have the ability to look inside the living human brain and track development across the lifespan.
In the past decade or so, mainly due to advances in brain imaging technology such as magnetic resonance imaging, or MRI, neuroscientists have started to look inside the living human brain of all ages, and to track changes in brain structure and brain function, so we use structural MRI if you'd like to take a snapshot, a photograph, at really high resolution of the inside of the living human brain, and we can ask questions like, how much gray matter does the brain contain, and how does that change with age?
And we also use functional MRI, called fMRI, to take a video, a movie, of brain activity when participants are taking part in some kind of task like thinking or feeling or perceiving something.
So many labs around the world are involved in this kind of research, and we now have a really rich and detailed picture of how the living human brain develops, and this picture has radically changed the way we think about human brain development by revealing that it's not all over in early childhood, and instead, the brain continues to develop right throughout adolescence and into the '20s and '30s.
So adolescence is defined as the period of life that starts with the biological, hormonal, physical changes of puberty and ends at the age at which an individual attains a stable, independent role in society.
(Laughter) It can go on a long time.
(Laughter) One of the brain regions that changes most dramatically during adolescence is called prefrontal cortex.
So this is a model of the human brain, and this is prefrontal cortex, right at the front.
Prefrontal cortex is an interesting brain area.
It's proportionally much bigger in humans than in any other species, and it's involved in a whole range of high level cognitive functions, things like decision-making, planning, planning what you're going to do tomorrow or next week or next year, inhibiting inappropriate behavior, so stopping yourself saying something really rude or doing something really stupid.
It's also involved in social interaction, understanding other people, and self-awareness.
So MRI studies looking at the development of this region have shown that it really undergoes dramatic development during the period of adolescence.
So if you look at gray matter volume, for example, gray matter volume across age from age four to 22 years increases during childhood, which is what you can see on this graph.
It peaks in early adolescence.
The arrows indicate peak gray matter volume in prefrontal cortex.
You can see that that peak happens a couple of years later in boys relative to girls, and that's probably because boys go through puberty a couple of years later than girls on average, and then during adolescence, there's a significant decline in gray matter volume in prefrontal cortex.
Now that might sound bad, but actually this is a really important developmental process, because gray matter contains cell bodies and connections between cells, the synapses, and this decline in gray matter volume during prefrontal cortex is thought to correspond to synaptic pruning, the elimination of unwanted synapses.
This is a really important process.
It's partly dependent on the environment that the animal or the human is in, and the synapses that are being used are strengthened, and synapses that aren't being used in that particular environment are pruned away.
You can think of it a bit like pruning a rosebush.
You prune away the weaker branches so that the remaining, important branches, can grow stronger, and this process, which effectively fine-tunes brain tissue according to the species-specific environment, is happening in prefrontal cortex and in other brain regions during the period of human adolescence.
So a second line of inquiry that we use to track changes in the adolescent brain is using functional MRI to look at changes in brain activity across age.
So I'll just give you an example from my lab.
So in my lab, we're interested in the social brain, that is the network of brain regions that we use to understand other people and to interact with other people.
So I like to show a photograph of a soccer game to illustrate two aspects of how your social brains work.
So this is a soccer game.
(Laughter) Michael Owen has just missed a goal, and he's lying on the ground, and the first aspect of the social brain that this picture really nicely illustrates is how automatic and instinctive social emotional responses are, so within a split second of Michael Owen missing this goal, everyone is doing the same thing with their arms and the same thing with their face, even Michael Owen as he slides along the grass, is doing the same thing with his arms, and presumably has a similar facial expression, and the only people who don't are the guys in yellow at the back — (Laughs) — and I think they're on the wrong end of the stadium, and they're doing another social emotional response that we all instantly recognize, and that's the second aspect of the social brain that this picture really nicely illustrates, how good we are at reading other people's behavior, their actions, their gestures, their facial expressions, in terms of their underlying emotions and mental states.
So you don't have to ask any of these guys.
You have a pretty good idea of what they're feeling and thinking at this precise moment in time.
So that's what we're interested in looking at in my lab.
So in my lab, we bring adolescents and adults into the lab to have a brain scan, we give them some kind of task that involves thinking about other people, their minds, their mental states, their emotions, and one of the findings that we've found several times now, as have other labs around the world, is part of the prefrontal cortex called medial prefrontal cortex, which is shown in blue on the slide, and it's right in the middle of prefrontal cortex in the midline of your head.
This region is more active in adolescents when they make these social decisions and think about other people than it is in adults, and this is actually a meta-analysis of nine different studies in this area from labs around the world, and they all show the same thing, that activity in this medial prefrontal cortex area decreases during the period of adolescence.
And we think that might be because adolescents and adults use a different mental approach, a different cognitive strategy, to make social decisions, and one way of looking at that is to do behavioral studies whereby we bring people into the lab and we give them some kind of behavioral task, and I'll just give you another example of the kind of task that we use in my lab.
So imagine that you're the participant in one of our experiments.
You come into the lab, you see this computerized task.
In this task, you see a set of shelves.
Now, there are objects on these shelves, on some of them, and you'll notice there's a guy standing behind the set of shelves, and there are some objects that he can't see.
They're occluded, from his point of view, with a kind of gray piece of wood.
This is the same set of shelves from his point of view.
Notice that there are only some objects that he can see, whereas there are many more objects that you can see.
Now your task is to move objects around.
The director, standing behind the set of shelves, is going to direct you to move objects around, but remember, he's not going to ask you to move objects that he can't see.
This introduces a really interesting condition whereby there's a kind of conflict between your perspective and the director's perspective.
So imagine he tells you to move the top truck left.
There are three trucks there.
You're going to instinctively go for the white truck, because that's the top truck from your perspective, but then you have to remember, "Oh, he can't see that truck, so he must mean me to move the blue truck," which is the top truck from his perspective.
Now believe it or not, normal, healthy, intelligent adults like you make errors about 50 percent of the time on that kind of trial.
They move the white truck instead of the blue truck.
So we give this kind of task to adolescents and adults, and we also have a control condition where there's no director and instead we give people a rule.
We tell them, okay, we're going to do exactly the same thing but this time there's no director.
Instead you've got to ignore objects with the dark gray background.
You'll see that this is exactly the same condition, only in the no-director condition they just have to remember to apply this somewhat arbitrary rule, whereas in the director condition, they have to remember to take into account the director's perspective in order to guide their ongoing behavior.
Okay, so if I just show you the percentage errors in a large developmental study we did, this is in a study ranging from age seven to adulthood, and what you're going to see is the percentage errors in the adult group in both conditions, so the gray is the director condition, and you see that our intelligent adults are making errors about 50 percent of the time, whereas they make far fewer errors when there's no director present, when they just have to remember that rule of ignoring the gray background.
Developmentally, these two conditions develop in exactly the same way.
Between late childhood and mid-adolescence, there's an improvement, in other words a reduction of errors, in both of these trials, in both of these conditions.
But it's when you compare the last two groups, the mid-adolescent group and the adult group where things get really interesting, because there, there is no continued improvement in the no-director condition.
In other words, everything you need to do in order to remember the rule and apply it seems to be fully developed by mid-adolescence, whereas in contrast, if you look at the last two gray bars, there's still a significant improvement in the director condition between mid-adolescence and adulthood, and what this means is that the ability to take into account someone else's perspective in order to guide ongoing behavior, which is something, by the way, that we do in everyday life all the time, is still developing in mid-to-late adolescence.
So if you have a teenage son or a daughter and you sometimes think they have problems taking other people's perspectives, you're right.
They do.
And this is why.
So we sometimes laugh about teenagers.
They're parodied, sometimes even demonized in the media for their kind of typical teenage behavior.
They take risks, they're sometimes moody, they're very self-conscious.
I have a really nice anecdote from a friend of mine who said that the thing he noticed most about his teenage daughters before and after puberty was their level of embarrassment in front of him.
So, he said, "Before puberty, if my two daughters were messing around in a shop, I'd say, 'Hey, stop messing around and I'll sing your favorite song,' and instantly they'd stop messing around and he'd sing their favorite song.
After puberty, that became the threat.
(Laughter) The very notion of their dad singing in public was enough to make them behave.
So people often ask, "Well, is adolescence a kind of recent phenomenon?
Is it something we've invented recently in the West?"
And actually, the answer is probably not.
There are lots of descriptions of adolescence in history that sound very similar to the descriptions we use today.
So there's a famous quote by Shakespeare from "The Winter's Tale" where he describes adolescence as follows: "I would there were no age between ten and three-and-twenty, or that youth would sleep out the rest; for there is nothing in the between but getting wenches with child, wronging the ancientry, stealing, fighting."
(Laughter) He then goes on to say, "Having said that, would any but these boiled brains of nineteen and two-and-twenty hunt in this weather?"
(Laughter) So almost 400 years ago, Shakespeare was portraying adolescents in a very similar light to the light that we portray them in today, but today we try to understand their behavior in terms of the underlying changes that are going on in their brain.
So for example, take risk-taking.
We know that adolescents have a tendency to take risks.
They do.
They take more risks than children or adults, and they are particularly prone to taking risks when they're with their friends.
There's an important drive to become independent from one's parents and to impress one's friends in adolescence.
But now we try to understand that in terms of the development of a part of their brain called the limbic system, so I'm going to show you the limbic system in red in the slide behind me, and also on this brain.
So the limbic system is right deep inside the brain, and it's involved in things like emotion processing and reward processing.
It gives you the rewarding feeling out of doing fun things, including taking risks.
It gives you the kick out of taking risks.
And this region, the regions within the limbic system, have been found to be hypersensitive to the rewarding feeling of risk-taking in adolescents compared with adults, and at the very same time, the prefrontal cortex, which you can see in blue in the slide here, which stops us taking excessive risks, is still very much in development in adolescents.
So brain research has shown that the adolescent brain undergoes really quite profound development, and this has implications for education, for rehabilitation, and intervention.
The environment, including teaching, can and does shape the developing adolescent brain, and yet it's only relatively recently that we have been routinely educating teenagers in the West.
All four of my grandparents, for example, left school in their early adolescence.
They had no choice.
And that's still the case for many, many teenagers around the world today.
Forty percent of teenagers don't have access to secondary school education.
And yet, this is a period of life where the brain is particularly adaptable and malleable.
It's a fantastic opportunity for learning and creativity.
So what's sometimes seen as the problem with adolescents — heightened risk-taking, poor impulse control, self-consciousness — shouldn't be stigmatized.
It actually reflects changes in the brain that provide an excellent opportunity for education and social development.
Thank you.
(Applause) (Applause)
I know what you're thinking.
You think I've lost my way, and somebody's going to come on the stage in a minute and guide me gently back to my seat.
(Applause) I get that all the time in Dubai.
"Here on holiday are you, dear?"
(Laughter) "Come to visit the children?
How long are you staying?"
Well actually, I hope for a while longer yet.
I have been living and teaching in the Gulf for over 30 years.
(Applause) And in that time, I have seen a lot of changes.
Now that statistic is quite shocking.
And I want to talk to you today about language loss and the globalization of English.
I want to tell you about my friend who was teaching English to adults in Abu Dhabi.
And one fine day, she decided to take them into the garden to teach them some nature vocabulary.
But it was she who ended up learning all the Arabic words for the local plants, as well as their uses -- medicinal uses, cosmetics, cooking, herbal.
How did those students get all that knowledge?
Of course, from their grandparents and even their great-grandparents.
It's not necessary to tell you how important it is to be able to communicate across generations.
But sadly, today, languages are dying at an unprecedented rate.
A language dies every 14 days.
Now, at the same time, English is the undisputed global language.
Could there be a connection?
Well I don't know.
But I do know that I've seen a lot of changes.
When I first came out to the Gulf, I came to Kuwait in the days when it was still a hardship post.
Actually, not that long ago.
That is a little bit too early.
But nevertheless, I was recruited by the British Council, along with about 25 other teachers.
And we were the first non-Muslims to teach in the state schools there in Kuwait.
We were brought to teach English because the government wanted to modernize the country and to empower the citizens through education.
And of course, the U.K. benefited from some of that lovely oil wealth.
Okay.
Now this is the major change that I've seen -- how teaching English has morphed from being a mutually beneficial practice to becoming a massive international business that it is today.
No longer just a foreign language on the school curriculum, and no longer the sole domain of mother England, it has become a bandwagon for every English-speaking nation on earth.
And why not?
After all, the best education -- according to the latest World University Rankings -- is to be found in the universities of the U.K. and the U.S.
So everybody wants to have an English education, naturally.
But if you're not a native speaker, you have to pass a test.
Now can it be right to reject a student on linguistic ability alone?
Perhaps you have a computer scientist who's a genius.
Would he need the same language as a lawyer, for example?
Well, I don't think so.
We English teachers reject them all the time.
We put a stop sign, and we stop them in their tracks.
They can't pursue their dream any longer, 'til they get English.
Now let me put it this way: if I met a monolingual Dutch speaker who had the cure for cancer, would I stop him from entering my British University?
I don't think so.
But indeed, that is exactly what we do.
We English teachers are the gatekeepers.
And you have to satisfy us first that your English is good enough.
Now it can be dangerous to give too much power to a narrow segment of society.
Maybe the barrier would be too universal.
Okay.
"But," I hear you say, "what about the research?
It's all in English."
So the books are in English, the journals are done in English, but that is a self-fulfilling prophecy.
It feeds the English requirement.
And so it goes on.
I ask you, what happened to translation?
If you think about the Islamic Golden Age, there was lots of translation then.
They translated from Latin and Greek into Arabic, into Persian, and then it was translated on into the Germanic languages of Europe and the Romance languages.
And so light shone upon the Dark Ages of Europe.
Now don't get me wrong; I am not against teaching English, all you English teachers out there.
I love it that we have a global language.
We need one today more than ever.
But I am against using it as a barrier.
Do we really want to end up with 600 languages and the main one being English, or Chinese?
We need more than that.
Where do we draw the line?
This system equates intelligence with a knowledge of English, which is quite arbitrary.
(Applause) And I want to remind you that the giants upon whose shoulders today's intelligentsia stand did not have to have English, they didn't have to pass an English test.
Case in point, Einstein.
He, by the way, was considered remedial at school because he was, in fact, dyslexic.
But fortunately for the world, he did not have to pass an English test.
Because they didn't start until 1964 with TOEFL, the American test of English.
Now it's exploded.
There are lots and lots of tests of English.
And millions and millions of students take these tests every year.
Now you might think, you and me, "Those fees aren't bad, they're okay," but they are prohibitive to so many millions of poor people.
So immediately, we're rejecting them.
(Applause) It brings to mind a headline I saw recently: "Education: The Great Divide."
Now I get it, I understand why people would want to focus on English.
They want to give their children the best chance in life.
And to do that, they need a Western education.
Because, of course, the best jobs go to people out of the Western Universities, that I put on earlier.
It's a circular thing.
Okay.
Let me tell you a story about two scientists, two English scientists.
They were doing an experiment to do with genetics and the forelimbs and the hind limbs of animals.
But they couldn't get the results they wanted.
They really didn't know what to do, until along came a German scientist who realized that they were using two words for forelimb and hind limb, whereas genetics does not differentiate and neither does German.
So bingo, problem solved.
If you can't think a thought, you are stuck.
But if another language can think that thought, then, by cooperating, we can achieve and learn so much more.
My daughter came to England from Kuwait.
She had studied science and mathematics in Arabic.
It's an Arabic-medium school.
She had to translate it into English at her grammar school.
And she was the best in the class at those subjects.
Which tells us that when students come to us from abroad, we may not be giving them enough credit for what they know, and they know it in their own language.
When a language dies, we don't know what we lose with that language.
This is -- I don't know if you saw it on CNN recently -- they gave the Heroes Award to a young Kenyan shepherd boy who couldn't study at night in his village, like all the village children, because the kerosene lamp, it had smoke and it damaged his eyes.
And anyway, there was never enough kerosene, because what does a dollar a day buy for you?
So he invented a cost-free solar lamp.
And now the children in his village get the same grades at school as the children who have jennifertorres@example.net.
(Applause) When he received his award, he said these lovely words: "The children can lead Africa from what it is today, a dark continent, to a light continent."
A simple idea, but it could have such far-reaching consequences.
People who have no light, whether it's physical or metaphorical, cannot pass our exams, and we can never know what they know.
Let us not keep them and ourselves in the dark.
Let us celebrate diversity.
Mind your language.
Use it to spread great ideas.
(Applause) Thank you very much.
(Applause)