Subtitles section Play video Print subtitles 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. I'm a physicist. 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. 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 a child of eight, something happened to me that changed my life and I wanted to be part of this grand search for a theory of everything. 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." 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?" 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. Unified Field Theory: A Theory of Everything An equation one inch long 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? All of it tied to an equation half an inch long. 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 alien from outer space, star ships, ray guns, invisibility shields, cities in the sky, that was for me. But after a few years, I began to notice something. 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 city in the sky. 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. Including computers, also biotechnology. All of that can eventually traced down to physics. 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 type two impossibilities, impossibilities that may take 1,000 years or more. That includes time travel, warp drive, higher dimensions, portals through space and time, star gates, worm holes. That's type two. And then we have type three, and those are things which simply violate all the known laws of physics, and they're very few of them. So in my life I've had two great passions. First is to help complete Einstein's dream of a theory of everything. An equation one inch long that would allow us to, "Read the mind of God." But the second passion of my life is to see the future. 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, 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 horse, I mean, that, we will have that flying car that we've always wanted to have in our garage. We will be able to create life forms that don't exist today. And so in other words, if you want to see the future, you have to understand physics, and you have to realize that 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. The 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. 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? 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. So, 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. In fact, British history dates to 1066 with William the Conqueror. 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? Well, believe it or not, that same comet, the very same comet that initiated the British monarchy, sailed over London once again in 1682. 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 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 falls, does the moon also fall? And the answer was, "Yes." And 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. 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. 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. In fact, he created 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. Everyone was talking about the comet, 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, 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." And of course, we don't know what Edmund Haley's reaction was, but I paraphrase, he must have said something like this, he said, "For God's sake, man, why don't you publish the greatest work in all of scientific history? 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, he must have said, "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, 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 have glorious photographs of the rings of Saturn. That's why we have fly-by's right past Neptune. 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 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. Aristotle said, "Objects in motion eventually stop, because they get tired." Newton says, "Objects in motion stay in motion forever." Sailing past Pluto, unless acted on by an outside force. The second law of motion says, force is mass times acceleration. And that equation made possible the Industrial Revolution. 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 outer space. In fact, Newton was the first human who could actually calculate how fast you have to run to jump to the moon. That was a number that mystified ancients. How do you get to the moon? Can you jump to the moon? Well, Newton could have calculated that number, 25,000 miles per hour, that's the escape velocity of the earth, a number which could have been calculated by Isaac Newton himself. 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?" So, rockets, the motion of planets, and even buildings in Manhattan, all of them owe their existence to Newton's laws of motion. You know, when I was a kid growing up in California, I would see pictures of the Empire State Building. And I said to myself, "How could that possibly build such a big building and not know that it's going to fall? I mean, 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. Every screw, every bolt, you can calculate precisely the tension on every single fragment of the Empire State Building, using Newton's second law of motion, force is mass times acceleration. That was the first force, when Newton unraveled the force of gravity, it ushered in the Industrial Revolution. 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 lightening 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?" Well, as time went by, scientists began to realize that the lightening bolts and the thunder can be duplicated on the earth. That we can actually create many lightening bolts using electricity. And with magnets, we can also unleash a new kind of force, the force of electricity and magnetism. 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. So this helped to usher in the age of discovery. Realize that before the compass, if you sailed the ocean blue, you would get lost. With the compass knowing the position of the stars, you can then begin to navigate over hundreds, thousands of miles in the ocean. So the discovery of compasses by the Chinese helped to usher in the Age of Discovery. And when people like Michael Faraday, who did this, 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 for children. 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 metal structure, you get shielded by this metal object and that's called a Faraday cage. Well, what Michael Faraday did was, he helped to unleash the second great revolution with something calls Faraday's Law. If I take a wire and I move a wire in a magnetic field, the magnetic field pushes the electrons in the magnet, creating an electrical current. That simple idea unleashed the electric revolution. A moving wire in a magnetic field, has this electrons pushed, creating a current, and that's why we have hydro-electric generators. That's why we have dams that can produce enormous amounts of power. That's why people build nuclear power plants. That's why we have room(?) right now. All of it due to the simple observation that a wire moving at a magnetic field, has its electrons pushed, creating an electric current. 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. That's exactly the same principal that lights up your house via a hydroelectric dam. 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, create electric fields, create magnetic fields, infinitum to create a wave?