[The Floating Univetsity]
My name is Professor Michio Kaku.
I’m a professor of theoretical physics at the City University of New York.
And I specialize in something called string theory.
[The Universe in a Nutshell–The Physics of Everything]
I’m a physicist. And some people ask me the question,
“What has physics done for me lately?
I mean, do I get better color television,
do I get better internet reception with physics?”
And the answer is yes.
You see, physics is at the very foundation of matter and energy.
We physicists invented the laser beam, we invented the transistor.
We helped to create the first computer.
We helped to construct the internet. We wrote the World Wide Web.
而且 还协助发明了电视 无线电通信 雷达 微波炉
In addition, we also helped to invent television, radio, radar, microwaves,
not to mention MRI scans, PET scans, x-rays.
In other words, almost everything you see in your living room,
almost everything you see in a modern hospital,
at some point or other, can be traced to a physicist.
Now, I got interested in physics when I was a child.
When I was eight, a great scientist had just died.
I still remember my elementary school teacher coming into the room
and announcing that the greatest scientist of our era has just passed away.
And that day, every newspaper published a picture of his desk.
The desk of Albert Einstein.
And the caption said, I’ll never forget,
“The unfinished manuscript of the greatest work of the greatest scientist of our time.”
我问自己 为什么他没有完成 何以这么难
And I said to myself, “Why couldn’t he finish it? I mean, what’s so hard?
It’s a homework problem, right?
Why didn’t he ask his mother?
Why can’t he finish this problem?
所以 作为一个8岁的小孩 我决定去弄明白问题所在
So as a child of eight, I decided to find out what was this problem.
Years later, I began to realize that it was the theory of everything,
the Unified Field Theory [the theory of everything]
An equation that would summarize all the physical forces in the universe.
An equation like E=mc².
That equation is half an inch long and that equation unlocks the secret of the stars.
Why do the stars shine? Why does the galaxy light up?
Why do we have energy on the earth?
But then there was another thing that happened to me when I was around eight years old.
I got hooked on the Saturday morning TV shows. In particular, Flash Gordon.
And I was hooked. I mean, every Saturday morning watching programs about
例如来自外太空的外星人 宇宙飞船 激光枪
alien from outer space, star ships, ray guns,
隐形护盾 天空之城等 都让我着迷无法自拔
invisibility shields, cities in the sky, that was for me.
But after a few years, I began to notice something.
首先 我开始充分注意到 我没有跟飞侠哥顿一样的金发碧眼
First of all, I began to notice that well, I didn’t have blond hair and blue eyes,
I didn’t have muscles like Flash Gordon,
but it was a scientist who made the series work.
In particular, a physicist.
He was the one who discovered the ray gun, the star ships.
He was the one who created the invisibility shield.
And then I realized something else.
If you want to understand the future, you have to understand physics.
Physics is at the foundation of all the gadgetry, the wizardry, all the marvels of the technological age,
all of it can be traced to the work of a physicist.
[Physics and the Impossible]
Most of science fiction is in fact well within the laws of physics,
but possible within maybe 100 years.
And then we have impossibilities that may take 1,000 years or more.
包括时空旅行 曲速引擎 高维空间
That includes time travel, warp drive, higher dimensions,
时间和空间的连接 星际通道 虫洞
portals through space and time, star gates, worm holes.
你知道 如果重返1900年去见祖父母 他们那时应该是质朴的农民
You know, if you were to meet your grandparents at the year 1900, they were dirt farmers back then.
They didn’t live much beyond the age of 40, on average.
Long distance communication in the year 1900 was yelling at your neighbor.
And yet, if they could see you now,
通过平板电脑 音乐播放器 卫星 全球定位系统以及镭射光线
with iPads and iPods and satellites and GPS and laser beams,
how would they view you?
They would view you as a wizard or sorcerer.
However, if we can now meet our grandkids of the year 2100,
how would we view them?
We would view them as gods, like in Greek mythology.
Zeus could control objects around him by pure thought.
Materialize objects just by thinking.
And there’re perks to being a Greek god,
Venus had a perfect body, a timeless body.
And we are beginning now to unravel the genetics at the molecular level, of the aging process.
And then Apollo, he had a chariot that he could ride across the heavens.
We will finally have that flying car that we’ve always wanted to have in our garage.
By the year 2100, we will have the power of the gods.
To paraphrase Arthur C. Clark,
“Any sufficiently advanced technology is indistinguishable from divinity.
So let’s now begin our story. [History of physics]
The history of physics is the history of modern civilization.
Before Isaac Newton, before Galileo,
we were shrouded with the mysteries of superstition.
People believed in all sorts of different kinds of spirits and demons.
What made the planets move?
Why do things interact with other things? It was a mystery.
让我们回到中世纪 举个例子 人们阅读亚里士多德的著作
So, back in the Middle Ages, for example, people read the works of Aristotle.
And Aristotle asked the question, “Why do objects move toward the earth? “
那是因为 他说道 “物体十分渴望与地球结合”
And that’s because he said, “objects yearn, yearn to be united with the earth.
And why do objects slow down when you put them in motion?
Objects in motion slow down because they get tired.”
These are the works of Aristotle, which held sway for almost 2,000 years
until the beginning of modern physics with Galileo and Isaac Newton.
[Beginning of Modern Physics]
When the ancients looked at the sky, the sky was full of mystery and wonder,
and in the year 1066, the most important date on the British calendar,
there was a comet, a comet which sailed over the battlefield of Hastings.
It frightened the troops of King Harold,
and a young man from Normandy, swept into England
and defeated King Harold at the Battle of Hastings,
creating the modern British monarchy.
But the question is, where did the comet come from?
What was this comet that mysteriously paved the way for the coming of the British monarchy?
好吧 信不信由你 正是那颗开辟了英国君主制的彗星
Well, believe it or not, that same comet, the very same comet that initiated the British monarchy,
sailed over London once again in 1682.
这一次 每个人都在问 “慧星从何而来”
This time, everyone was asking the question, “Where do comets come from?”
Do they signal the death of the king?
Why do we have messengers from the heavens in the sky?”
Well, one man dared to penetrate the secrets of comets, and that was Isaac Newton.
In fact, when Isaac Newton was only 23 years old,
he stumbled upon the universal force of gravitation.
According to one story, he was walking on his estate in Woolsthorpe,
and he saw an apple fall.
And then Isaac Newton saw the moon, and then he asked the key question which helped to unlock the heavens.
If apples fall, does the moon also fall?
And the answer was, “Yes.”
And that answer overturned thousands of years of mystery and speculation about the motions of the heavens.
The moon is in freefall, just like an apple.
The moon is constantly falling toward the earth.
然而月亮不会撞击地球 因为月亮围绕地球运行 而且地球是球体
It doesn’t hit the earth, because it spins around the earth, and the earth is round,
but it’s acting under a force, a force of gravity.
[Four Forces of the Universe–Gravity]
So Newton immediately tried to work out the mathematics
and he realized that the mathematics of the 1600’s was not sufficient to work out the motion of a falling moon.
So what did Isaac Newton do?
When he was 23 years old, not only did he stumble upon the force of gravity,
but he also created calculus.
实际上 当你还是大一新生时 牛顿以你学习微积分的速度创造了这一学科
In fact, he created calculus at the rate at which you learn it, when you are a freshman in college.
And why did he create calculus?
To calculate the motion of a falling moon.
The mathematics of his age was incapable of calculating the trajectories of objects moving under an inverse square force field,
and that’s what Isaac Newton did.
He worked out the motion of the moon.
And then he realized that if he understands the moon,
he also understands the motion of the planets in the solar system.
And Isaac Newton invented a new telescope.
It was the reflecting telescope and he was tracking the motion of this comet.
Well, it turns out that everyone was talking about the comet,
including a rather wealthy Englishman by the name of Edmund Haley.
So Edmund Haley, being a wealthy merchant, decided to make a trip to Cambridge
to talk to England’s illustrious scientist, Sir Isaac Newton.
Well, Edmund Haley asked Newton, “What do you make of this comet?
No one understands comets, they’re a mystery.
They’ve been fascinating people for centuries, for millennia, what are your thoughts?”
And then, I paraphrase, but Isaac Newton said something like this,
他说：“哦 很简单 彗星是以完美的椭圆轨迹运动的
he said, “Oh, that’s easy. That comet is moving at a perfect ellipse.
It’s moving in an inverse square force field.
I’ve been tracking it every day with my reflecting telescope
and the path of that comet conforms to my mathematics exactly.”
当然 我们不知道艾德蒙·哈利的反应 但我猜测如下
And of course, we don’t know what Edmund Haley’s reaction was, but I paraphrase,
he must have said something like this, “For God’s sake, man,
why don’t you publish the greatest work in all of scientific history?
如果你是对的 你就破译了恒星的秘密 以及天空的秘密
If correct, you have decoded the secret of the stars, the secret of the heavens.
Nobody understands where comets come from.”
And then Newton responded and said, “Oh, well, it costs too much.
I mean, I’m not a wealthy man,
it would cost too much to summarize this calculus that I’ve invented
and to work out all the motion of the stars.”
And then Haley must have said this,
“牛顿先生 我有钱 我做生意赚了不少钱
“Mr. Newton, I am a wealthy man. I have made my fortune in commerce.
I will pay for the publication of the greatest scientific work in any language.”
And it was Principia.
The principals, the mathematical principals that guide the heavens.
Believe it or not, this is perhaps one of the most important works ever written
by a human being in the 100,000 years since we evolved from Africa.
Realize that this book sets into motion a physics of the universe.
Forces that control the motion of the planets,
forces which can be calculated,
支配炮弹 火箭 鹅卵石等一切运动的力量
forces which govern the motion of cannonballs, rockets, pebbles, everything that moves,
moves according to the laws of motion and the calculus of Sir Isaac Newton.
In fact, even today, when we launch our space probes, we don’t use Einstein’s equations,
they only apply when you get near the speed of light or near a black hole.
We use Newton’s laws of gravity.
They are so precise that when we shoot a space probe right past the rings of Saturn,
we use exactly the same equations that Isaac Newton unraveled in the 1600’s.
That’s why we’ve been able to unravel the secrets of the solar system,
compliments of the laws of motion of Isaac Newton.
So what Newton did was not only did he set into motion the ability to calculate planets,
he also set into motion a mechanics.
Machines now operated upon well-defined laws:
Newton’s three laws of motion.
The first law of motion says that
that objects in motion stay in motion forever, unless acted on by an outside force.
You see that in an ice skating rink.
You should a puck and it goes all the way down forever,
unless acted upon by an outside force.
That’s different from Aristotle’s law of motion.
亚里士多德说 “运动的物体总会停下 因为它们累了”
Aristotle said, “Objects in motion eventually stop, because they get tired.”
The second law of motion says, force is mass times acceleration.
And that equation made possible the Industrial Revolution.
蒸汽机 火车头 工厂 机器的实现
Steam engines, locomotives, factories, machines,
all of it due to the mechanics set into motion by Isaac Newton’s second law of motion,
force is equal to mass times acceleration.
And then Newton had a third law of motion.
For every action, there’s an equal and opposite reaction,
that’s the law of rockets.
That’s why we have rockets that can sail into outerspace.
所以这一课是 当科学家解开宇宙第一种力 万有引力
So the lesson here is, when scientists unravel the first force of the universe, gravity,
that set into motion the Industrial Revolution.
A revolution which toppled the kings and queens of Europe,
which displaced feudalism, ushering in the modern age.
All because a 23-year-old gentleman looked up and asked the question,
“Does the moon also fall?”
You know, when I was a kid growing up in California,
I would see pictures of the Empire State Building.
我对自己说 怎么能建那么高的大楼 还不会倒塌
And I said to myself, “How could that possibly build such a big building and not know that it’s going to fall?
Why doesn’t it fall? They didn’t build scale models of the thing,
you couldn’t have an Empire State Building that big to test whether it’s going to fall or not.
How did they know ahead of time that that building wouldn’t fall?
And the answer is: Newton’s laws of motion.
In fact, today, I teach Newton’s laws of motion,
and you can actually calculate the forces on every single brick of the empire state building,
using Newton’s second law of motion, force is mass times acceleration.
When Newton unraveled the force of gravity, that was the first force.
Now, let’s take a look at the second force,
an even greater force which has touched all of our lives,
and that is the electromagnetic force.
Ever since humans saw lightning bolts light up the sky,
ever since they were terrified by the sound of thunder,
they’ve been asking, “Do the gods propel lightening bolts and create thunder?
Are they angry at us?”
Scientists began to realize that the lightning bolts and the thunder can be duplicated on the earth.
That we can actually create mini lightning bolts using electricity.
But it wasn’t until the 1800’s that finally we begin to unlock the second great force
which rules the universe, the electromagnetic force.
Michael Faraday would give Christmas lectures in London,
fascinating everyone from adults to children.
And he would demonstrate the incredible properties of electricity.
Some people, for example, ask a simple question.
If you’re in a car or an airplane, you get hit by a lightening bolt,
why don’t you all get electrocuted? Why don’t you all die?
Well, Faraday answered the question.
He would create a cage.
He would walk into this steel cage, electrify it,
and he wouldn’t get electrocuted at all.
That’s called a Faraday cage
and every time you walk into a metal structure, you get shielded by this metal object.
Well, what Michael Faraday did was,
he helped to unleash the second great revolution with something calls Faraday’s Law.
磁场中运动的电线 在电子的作用下 制造出电流
A moving wire in a magnetic field, has this electrons pushed, creating an electrical current.
That simple idea unleashed the electric revolution.
And that’s why we have hydroelectric generators,
dams that produce enormous amounts of power,
That’s why people build nuclear power plants.
That’s why we have electricity in this room right now!
On a very small scale, you use that in your bicycle.
When you put a bicycle lamp on your bicycle, the turning of the wheel spins a magnet.
The magnet then pushes electrons in a wire
and that’s why electricity lights up in your bicycle lamp.
So in other words, electricity and magnetism were unified into a single force.
We once thought that electricity and magnetism were separate.
Now we know they are in fact the same force.
So if a moving magnet can create an electric field,
this means that a moving electric field can create a magnetic field.
But if they can create each other,
why can’t they oscillate and create a wave?
So that moving electric fields create magnetic fields,
磁场激发电场 电场激发磁场 无限循环下去
create electric fields, create magnetic fields, infinitum to create a wave?
Well, around the time of the American Civil War,
a mathematical physicist, James Clerk Maxwell,
calculated, using the work of Faraday, the velocity of this wave.
And in one of the greatest breakthroughs of all time,
James Clerk Maxwell calculated the velocity of this wave
and found out it was the velocity of light.
And then he made this incredible discovery: this is light.
That’s what light is.
It doesn’t by accident travel at the speed of electricity, it is light itself.
And the equations were written down by James Clerk Maxwell.
Unfortunately, Michael Faraday himself did not have a formal education.
He could not put into mathematical form his own work.
James Clerk Maxwell was a theoretical physicist, just like myself.
He wrote down the mathematical physics of oscillating electric fields and magnetic fields
and they are called Maxwell’s equations.
These equations have to be memorized by every physicist in grad school.
You cannot get your PhD without memorizing these equations.
Every engineer deals with radar and radio has to memorize these equations.
如果你去我取得博士学位之地 伯克利 可以买件T恤 上面印着
And so, if you go to Berkley, where I got my PhD, you can buy a t-shirt which says,
“In the beginning God said,
the four-dimensional divergence of an antisymmetric, second rank tensor equals zero, and there was light.”
Ladies and gentlemen, this is the equation for light.
What does this mean for us?
The consequences of the electromagnetic revolution touch all of us.
This is a picture of the earth from outer space. Look at this picture.
you can actually see the fruits of all of our efforts to create electricity, to energize our lives,
in one picture, seeing the earth from outer space.
So let’s now talk about how Faraday and Maxwell’s work touches your life as well.
This is the internet. The internet is a simple byproduct of the electromagnetic force.
And you can see that where there is the internet, there is prosperity.
There is science, there’s entertainment, there’s economic activity.
Where there’s no internet, there’s poverty.
And in the future, the internet will be miniaturized and it will be placed in your glasses.
Your glasses will recognize people’s faces
and display their biography next to the image as you talk to them,
and then when they speak Chinese to you,
your glasses will translate Chinese into English
and print out subtitles right beneath their image.
So in the future, you will know exactly who you are talking to without even talking to them,
and this means that at a cocktail party,
if you’re looking for a job, but you don’t know who the heavy hitters are,
in the future you will know exactly who to suck up to.
In the future, chips will only cost a penny,
because we can manufacture tinier and tinier transistors.
You will have Faraday’s electromagnetic force inside your body.
This is a pill. It has a chip in it.
The chip is smaller than an aspirin pill.
It also has a TV camera and a magnet.
When you swallow it, the magnet guides the camera,
taking pictures of your stomach, your intestines,
because we all know what middle-aged men fear the most: colonoscopies.
And, this gives new meaning for the expression “intel inside.”
Now, let’s talk about the next great forces which rule the universe.
We talked about gravity, which allows us to calculate the motion of the planets.
The mechanics created by Newton helped to unleash the Industrial Revolution.
Michael Faraday worked out the electromagnetic force, which gave us the wonders of the electric age.
And now, let’s talk about the nuclear age, the stars and the sun.
People have been fascinated by the sun,
Apollo was the god that strode across the heavens in his fiery chariot.
但是 如果太阳能源是煤或油 你计算能燃烧多久
But hey, when you calculate how long coal or oil will burn like the sun,
you realize that in just a few hundred years, the sun would burn to a crisp.
So what could possibly last for billions of years?
There must be a new force, a nuclear force.
Einstein and others helped to unravel the secret of the stars.
The nuclear force comes in two types, weak and strong.
The weak nuclear force governs radioactive decay.
The strong nuclear force is one of the strongest forces in the entire universe.
It’s so strong it holds our protons together, ever since Genesis, the beginning of time.
The equation which allows for the liberation of energy is Einstein’s famous equation E=mc².
爱因斯坦所说明的是 物体运动的越快 质量越大
What Einstein showed was that the faster you move, the heavier you get.
So your weight is not a constant.
When you move very rapidly you get heavier,
something which we measure every day in the laboratory.
Now, this means that the energy of motion transformed into mass, because you get heavier.
Now, listen carefully.
The faster you move, the heavier you get.
Which means that the energy of motion, “E” turns into “m”, your mass.
And the relationship between E and m is very simple,
it takes one second to write it down on a sheet of paper,
it is exactly E=mc².
So the nuclear force helped to explain the secret of the sun.
But it also created a Pandora’s box,
because inside the nucleus of the atom, are particles.
And when you smash these particles, what do you get? More particles.
And when you smash them, what do you get? More particles.
In fact, we are drowning in subatomic particles.
每次我们砸碎原子 就有成百上千 成千上万的粒子
Hundreds, thousands of subatomic particles every time we smash atoms.
Now, we smash atoms using something called atom smashers, or particle accelerators.
I built my own particle accelerator when I was in high school.
When I was in high school, I went to my mom one day and I said,
“Mom, can I have permission to build a 2.3 million electron volt betatron particle accelerator in the garage?”
妈妈说 “当然可以 为什么不呢
And my mom said, “Sure, why not?
And don’t forget to take out the garbage!”
我去了西屋公司 作为一个高中生 我索要了400磅的再生铁
So I went into Westinghouse. And as a high school kid I asked for 400 pounds of transformer steel.
I asked for 22 miles of cooper wire.
Because I wanted to create a six kilowatter, 10,000 gauss magnetic field, to energize my atom smasher.
With 22 miles of copper wire, how could you wind it?
We did it on the high school football field.
I put 22 miles of copper wire on the goalpost, gave it to my mother,
she ran to the 50 yard line unraveling the spool of wire,
she gave it to my father who then ran to the goalpost
and we wound 22 miles of copper wire on the high school football field.
Well, finally my atom smasher was ready.
It consumed six kilowatts of power, that’s every single ounce of power my house could deliver.
我塞紧耳朵 闭上眼睛 打开了能量开关
I plugged my ears, I closed my eyes, I turned on the power,
and I heard this huge crackling sound
as six kilowatts of power surged through my capacitor bank
然后听到“啪 啪 啪”声音
and then I heard a “pop pop pop” sound
as I blew out every single circuit breaker in the house.
The whole house was plunged in darkness.
我可怜的妈妈 每次她回家看到灯光闪烁 熄灭
My poor mom, every time she’d come home she’d see the lights flicker and die.
And she must’ve wondered “why couldn’t I have a son who plays baseball?”
Why can’t he learn basket ball?
And for god’s sake why can’t he find a nice Japanese girl?”
I mean, why does he have to build these machines in the garage?
Well, these machines that I built in my garage earned the attention of a physicist
Edward Teller, father of the hydrogen bomb.
And he arranged for me to get a scholarship to Harvard.
And my career got a head start! He knew exactly what I was doing.
I didn’t have to explain to him that I was experimenting with antimatter.
I was creating anti-electrons in my mom’s garage,
and using atom smashers to eventually create beams of antimatter.
Antimatter is the opposite of matter.
It has an opposite charge.
So an electron has negative charge.
The positron, or anti-electron, has positive charge.
This means that you can now create anti-molecules and anti-atoms.
Anti-hydrogen was made at CERN, outside Geneva, Switzerland
And also at Fermilab outside Chicago
Where you have anti-electrons circulating around anti-protons.
And in Brookhaven National Laboratory on Long Island just recently
they detected anti-helium!
We have two anti-protons with two anti-neutrons to create anti-helium.
For every piece of matter there is a counterpart made out of anti-matter.
And when the two collide, by the way, it releases the greatest energy source in the universe.
It is 100 percent conversion of matter to energy by Einstein’s equations E=mc squared.
[The Standard Model]
Inside the nucleus of the atom we have particles upon particles when you smash them apart.
In the 1950’s we were drowning in subatomic particles.
事实上 原子弹之父 尤利乌斯·罗伯特·奥本海默曾声明
In fact, J. Robert Oppenheimer, the father of the atomic bomb, once made a statement.
He declared that “the Nobel Prize in physics should go to the physicist who does not discover a new particle this year.”
That how many particles were being discovered.
So, let’s talk about the Particle Zoo.
至今 物理学家已经发现成百上千 成千上万的次原子粒子
Right now, we physicists have unlocked hundreds, thousands of subatomic particles.
And we’ve been able to piece them together into a jigsaw puzzle.
It’s called the “standard model.”
It has 36 quarks, 19 free parameters,
3代夸克 无韵律 无原因
3 generations of quarks, no rhyme, no reason,
but this is the most fundamental basis of reality that we physicists have been able to construct.
Billions of dollars. 20 Nobel prizes.
have gone into the creation of the standard model.
and it is the ugliest theory known to science, but it works.
There’s one piece missing, and that one piece missing is called the Higgs-Boson.
We expect to find it. We want to create a higher version of this theory
and that theory, we think, is string theory.
[String Theory–a theory of everything?]
String theory is based on the simple idea that all the four forces of the universe.
Gravity, electromagnetic force, and the two nuclear forces, can be viewed as music.
Music of tiny little rubber bands.
So if I had a super microscope,
and I could look right into the heart of an electron,
what would I see?
I would see a vibrating rubber band.
And if I “twang” it, it turns into a neutrino.
I “twang” it again and it turns into a quark.
I “twang” it again and it turns into a Yang-Mills particle
In fact, if I “twang” it enough times,
I get thousands of subatomic particles that have been cataloged patiently by physicists.
String theory, we think, is a theory of everything.
Now, string theory, in turn, can be summarized in an equation about an inch long
That’s my equation!
This is called string field theory. And how will we test it?
We are building a machine.
The biggest machine of science ever built in the history of the human race.
Outside Geneva, Switzerland.
It is the Large Hadron Collider.
So the Higgs-Boson, we think, will be created by the Large Hadron Collider.
A tube 17 miles in circumference
with two beams of protons circulating in opposite directions
Then slamming together creating a shower of particles,
and among these particles we hope to find the Higgs-Boson, but not only that.
We hope to find particles even beyond the Higgs-Boson.
The next set of particles beyond the Higgs-Boson are “sparticles”
The next layer of the jigsaw puzzle are called sparticles—super particles
Nothing but higher vibrations, higher musical notes of a vibrating string.
And what else can we do?
We can also unlock secrets of the big bang.
You see, Einstein’s equations break down and the instant of the big bang and the center of a black hole.
The two most interesting places in the universe
are beyond our reach using Einstein’s equations.
We need a higher theory,
and that’s where string theory comes in.
String theory takes you before the Big Bang, before Genesis itself.
And what does string theory say?
It says that there is a multiverse of universes.
Where did the Big Bang come from?
Well, Einstein’s equations give us this compelling picture
that we are like insects on a soap bubble.
A gigantic soap bubble which is expanding.
and we are trapped like flies on fly paper, we can’t escape the soap bubble
and that’s called the Big Bang Theory.
String theory says there should be other bubbles out there in a multiverse of bubbles.
When two universes collide it can form another universe.
When a universe splits in half it can create two universes,
and that, we think, is the Big Bang.
The Big Bang is caused by either the collision of universes
or by the fissioning of universes.
If there are other dimensions, if there are other universes,
can we go between universes?
Well that, of course, is very hard,
however, Alice in Wonderland gives us a possibility
that maybe one day we might create a wormhole between universes.
This is a wormhole.
Think of taking a sheet of paper and putting two dots on it.
The shortest distance between two points is a straight line.
But if I can fold, if I can fold that sheet of paper
Then perhaps I can create a shortcut.
A shortcut through space and time, called a wormhole.
This is a genuine solution of Einstein’s equations.
We can actually see this in string theory.
The question is: how practical is it to go through one of these things?
我们不知道 事实上 现今的物理学家之间有个辩论
We don’t know. In fact there’s a debate among physicists today,
众多物理学家 例如史蒂芬·霍金参与进来 试着寻找
Stephen Hawking, many physicists are jumping into the game of trying to figure out
whether it’s physically possible to go all the way through a wormhole.
Because if you could, then you might be able to use this as a time machine.
Since string theory is a theory of everything, it’s also a theory of time.
And time machines are allowed in Einstein’s equations,
but to build one is extremely difficult.
Far more energy is required than a simple Delorean with plutonium.
[Why seek other universes?]
你知道 上万亿年后 宇宙将变得极其冷
You know, trillions of years from now the universe is going to get awfully cold.
We think the universe is headed for a big freeze.
All the stars will blink out.
Stars will cease to twinkle,
Universe will be so big,
it’ll be very cold.
At that point all intelligent life in the universe must die.
The laws of physics are a death warrant for all intelligent life.
There is only one way to escape the death of the universe,
and that is leave the universe.
We are now, of course, entering the realm of science fiction,
but at least now we have equations,
equations of string theory which will now allow us to calculate
if it is possible to go through a wormhole,
to go to another universe where it’s warmer,
and perhaps we can start all over again.
[A Fifth Force]
If you were to summarize the march of physics over the last 10,000 years,
it would be the distillation of the laws of nature into four fundamental forces.
万有引力 电磁力 两种核力
Gravity, electricity and magnetism, and the two nuclear forces.
But then the question is “is there a fifth force?”
A force beyond the forces that we can measure in the laboratory.
And believe it or not there are physicists who have actually looked very carefully for a fifth force.
Some people think maybe it’s psychic phenomena. Maybe it’s telepathy.
Maybe it’s something called psi power.
Maybe it’s the power of the mind. Maybe consciousness!
Well, I’m a physicist.
We believe in testing theories to make sure they are falsifiable and reproducible.
我们想确保每一次 理论都靠得住 没有例外
We want to make sure that on demand your theory works every single time without exception.
And if your theory fails one time, it’s wrong.
In other words, Einstein’s theory has to work every single time without exception.
One time Einstein’s theory is proven to be wrong,
the whole theory is wrong.
Well, so far we can reproduce these four physical theories,
but a fifth theory cannot be reproduced.
We’ve looked for it. Some people think that maybe a fifth force may be short range.
Like, not over the nucleus of an atom, but ranging over several feet.
And we can’t find any.
We physicists in the last ten years have discovered a new energy source
larger than the galaxy itself.
Realized in our universe today, 73 percent of our universe,
the matter and energy, 73 percent is in the form of dark energy.
The energy of nothing!
That’s what’s blowing the galaxies farther and farther apart.
That’s the energy of the Big Bang itself.
Kids ask the question, “If the universe banged, what made it bang?”
And the answer is dark energy.
73 percent of the universe’s energy is dark energy.
23 percent is dark matter.
Dark matter is invisible matter.
If I held it in my hand it would go right through my hand.
It holds the galaxy together.
23 percent of the universe is dark matter.
Stars made out of hydrogen and helium
make up four percent of the universe.
And then what about us?
We, the higher elements.
由氧 碳 氮 钨 铁组成
We made out of oxygen, carbon, nitrogen, tungsten, iron.
We make up .03 percent of the universe.
In other words, we are the exception.
The universe is mainly made out of dark energy.
The universe is mainly made out of dark matter.
Overwhelming the stars, overwhelming the galaxies in fact.
Now what is dark matter, which makes up 23 percent of the universe?
No one knows.
String theory gives us a clue,
but there’s no definitive answer.
[The Future of Universe]
So in other words, for you young aspiring physicists out there in the audience,
You may be saying to yourself right now,
“Why should I go into physics?
Because you guys already have a candidate for the unified field theory, right?”
Just realize that every single physics textbook is WRONG.
Every single physics textbook on the Earth says
that the universe is mainly made out of atoms.
Right? There it is!
The universe is mainly made out of atoms. Wrong!
In the past ten years we have come to the realization
that most of the universe is dark.
And there’s a whole shelf full of Nobel Prizes for the young people
who can figure out the secret of dark matter and dark energy.
Let me give some advice to you if you are a young physicist,
perhaps just getting out of high school,
You have dreams of being Einstein,
you have dreams of working on string theory and stuff like that
and then you hit freshman physics.
Let me be blunt:
We physicists flunk most student taking elementary physics.
And we’re more or less encouraged to do so by the engineering department.
We don’t want to train engineers who make bridges that fall down.
We don’t want to create engineers that create skyscrapers that fall over.
There’s a bottom line: you have to know the laws of mechanics.
So before you can work with the laws of Einstein,
你要先学习摩擦定律 杠杆 滑轮和齿轮
you have to work with the laws of friction, levers, pulleys and gears.
因此 基础物理学阶段 我们有很高的淘汰率
As a consequence we have a very high flunk-out rate in elementary physics.
如果你 年轻的物理学者刚从高中毕业 对未来充满憧憬
So if you’re a young physicist graduating from high school with stars in your eyes,
and you encounter freshman physics for the first time, watch out!
If you have a rough time, that’s the way it is.
I started out my life as an experimental physicist. Then I went to Harvard
and then I talked to my adviser, one of the world’s greatest experiment physicists, Professor Pound.
And he told me maybe it’s time to give it a rest. He said to me,
他说 “你应将技能放在喜欢的事物上 对你来说就是理论”
“Your skills are much better suited to what you love the most, which is theory.”
“Mathematics. The world of higher dimensions.”
And I realized that he was probably right.
The thing about physics, or science that really intrigues me the most
is to find the most fundamental basis for everything.
Rather than trying to massage a theory, or make a theory prettier.
Why not find out why it works? What makes it tick?
And that’s what I do for a living. I’m a theoretical physicist.
Thank you very much!
[The Floating University]