Understanding Magnetism
“ If somehow the laws of physics change that there was no magnetism. I mean all backs are rot and God knows what the world will be like. We in truly would be so profoundly different that en… you could have said oh… there wouldn’t have cars, or anything so fabulous that we wouldn’t have light, light that the first thing mentioned in the Bible, No. 1, God separated the darkness from the light.”ffice
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--------- Richard Frankel, physicist, CaliforniPa Polytechnic Institute
Since the first moments of creation, magnetism has been a force in our universe, so powerful, so fundamental, nothing in our world would exist without it, not even us.
The Smallest Miracle…
In the beginning, humans first discovered magnetism as a small miracle, a dark stone that attracted iron in an invisible force. In a time, when the fire was tamed to fashion tools, when the stars were all named, here was something truly magical, a rock with mind of its own. It was an effect without a cause.
“when science began , began in a Greek colony of Melidas(梅利达斯)，650 B.C. in a Thursday morning, … or something like that… , people started to say look,‘ let’s look for the philosophical explanation for this complex world’, and load stones were part of this curious complexity.” Load Stone (天然磁石) is an iron awe, a natural magnet, the Greeks found it in the province of Magnitia(梅格尼西亚), and that’s how magnets got their name.
--------Leon Ledeman, Nobel Laureate, Director Emeritus Fermilab
Hippoctates，while he was busy in inventing medicine, thought the thing is curious as the load stone must be good for something. So he claimed it had healing powers.
By the Middle Ages, load stone was believed to increase elegance and charm and to restore merry or harmony.
People believe it could cure everything, from heart disease to gout.
Mariners told tales of ships sank when load stone mountains pulled all the nails from their holes. By 1269, 派里格里纳斯began to explain the magic. He reported that all load stones, if allowed to rotate freely, pointed in the same direction.
“ The rock has some very very special properties. It does turn at…”
派里格里纳斯also demonstrated that the rock could transferred its magnetic power to an ordinary iron needle.
“You can hang it upon a deck. Sailors were going to sail North.”
Travelers no longer had to depend on sun and stars to guide them. Magnetized piece of iron flowed or mounted on a pivot(枢轴) and you will have a compass, ready to guide the Sunday sailor around their bay, or Columbus to the New World.
“ The stone disclosed to Flavio its secret love for the Pole, but he disclosed it to the sailors.” ----- Johannes Stradanhus, 1600
In 1600, William Gilbert revolutionary treatises on the magnet disclosed that prodding hot iron induces magnetism in the metal. He also reported that magnetized needle, when floated in water, not only pointed North, but also sledded down toward the earth.
The needle seems to be reaching for something. For Gilbert this meant the earth had a magnetic soul.
He was right. The earth itself is a giant magnet. Researchers today believe that magnetism comes from currents in the liquid metals in the earth core, but there are as still many questions as answers. We do know that magnets come in all sizes, as large as a world, as small as an atom.
“Today we know that the origins of all magnetism are in the atom, and they come from the way the world works, the way the world works that atom consists of electrical charges. They have names; electrons and nuclear sects. They actually are two parts of atom. And nucleons are the tiny, small things floating in the middle of a giant volume, in which electrons with surround. If we have the electron charge that is moving, you will create a magnet field. But if these magnets miss their lines, as here is in South Pole and North Pole, there is in South Pole and in North Pole, all in every each way, and that net effect is zero magnetism. That is what we can say that there is no magnetism.”
But in some metals like iron clumps of the atoms line-up, and point their poles in the same direction, these clumps are called domains（磁畴）.
“And suddenly you have the accumulation that all North Poles are in one side and all South Poles are in the other side. And You will hope a bar magnet.”
“A little more, or and look at that…” sprinkle iron filings(铁屑) over a bar magnet and you can see magnetism. The magnetic field is not uniform. It has invisible magnetic lines looping out of the top and the bottom of the magnet.
“ Look at the beautiful magnetic lines, of course.”
The earth is a little large, but if you could surround it with iron dust you will see the same loops of the magnetic force. Like all magnets, the earth field lines converge at its magnetic poles. It is this field that protects us from cosmic radiation.
“ The sun has been a big powerful star, constantly ejecting a rather powerful stream of charged particles that fly into the space and when they hit the planet of the earth, the radiation that they caused could damage us and give us skin cancer and cataracts(白内障). The earth magnetic field channels those charged particles and acts as a barrier to prevent them from striking the atmosphere. However, the earth field dives in to the atmosphere at the North Pole and the South Pole, when those charged particles hit the atmosphere, they ionize them in to plasmas(离子体) as we could see here. “ Plasma” a superheated gas in which electrons are stripped from their nuclear eye.
“And it is so sheets of plasma that you see, that replay in beautiful light that we call them the Northern Lights.”
------ Steve Fairfax, Engineer Plasma Fusion Center, MIT
This current of light lives in the legends of the people in the North. The Inuit in Alaska thought the all of light signified the war of celestial battles. 16th-century Germans believed the sky was on fire. To the Chechi people(恰奇人) of Siberia, the souls of their dead lived on in the light.
Even today the Northern lights have the power to capture the human imagination. The magnetic forces that shape the glow in sky can also be used to push products.
Far to the south in the heat of California’s Death Valley, the history of the earth’s magnetic field is locked in the layers of rock. When rock forms, some of its magnetic particles lining up with the planetary magnetic field. By cutting the samples form different layers of stone, researchers can show the earth has had the same magnetic alignment for 700,000 years.
But hit a layer lower than that, and rocks all there show in times when compass needle not always pointed north.
“The one of the strangest things in magnetism is the magnetism reversal. The idea that entire planet magnetic field can come discoupled from the rotating axis. As it’s pointing North, magnetic field may point east for a while, and then reestablished itself in, in the compass needle would point south.”
------ Joseph Kirschvink, Geobiologist, California Institute of Technology
Death Valley is an ideal place to learn about magnetic reversals.
“There is an active force zone that runs through the bottom of Death Valley here. It has taken these lakebeds, turn them on the end, force them up, and then its streams just set it down through them to almost 100% exposure. From few places we can go as here, right, magnetic fields started in a normally magnetized state, say here, and 3 and 4 meters above there, describes the reverse state. And yet we are recording the history of this field. Each little bed when its form preserves the precisely magnetic field of the time.”
Core samples are analyzed in a magnetometer( 磁力计) to determine the strength and direction of the magnetic field. Researchers can use that information to explore a geomagnetic map that tells the history of earth’s field history of reversals.
Far from Death Valley, there are other reliable places to study geomagnetism.
Volcanoes, melting magnet erupted from the earth secrete chambers, is rich in iron. When it cools it locks in clues, not just about the earth magnetic fields, but also about how the continents were formed.
“ It is a fact how the liquid magnetism comes up, getting in its place liquefied and cools. They cramp to become magnets as they become magnetic, they walk in the magnetic direction, parallel to the earth field of the time.”
Beneath the surface of the Ocean, cooled and locked in the magnetic information as it creates new sea floor. Over millions of years, a strike patterns of forms, creating a time line of earth’s field reversals. These patterns tell geologists that, as new strikes form, the continents are pushed apart. This observation led to a major breakthrough understanding the way the earth works, the theory of plate tectonics.(板块理论)
“There no parallel in history of science where one set of observations make such a key change in entire field. Perhaps owing to, when it is comparable, say, as the Darwin’s revolution of biology, it still has divisions, but the plate evolution that is so much the thing in Geology and that was driven by magnetism .”
Whether on the seafloor or in the Death Valley, magnetic strikes also hold clues about when the earth field might reverse again.
Studies indicate that we are in a period when the magnetic field is declining fast, 15% since the year 1670. If the present trend continues, the earth could lose its entire magnetic field in about 2,000 years.
Compasses would be useless. Northern light would vanish and our globe would be exposed to cosmic radiation. But no one can be sure if this will happen. Magnetic field could also reverse its trend and began gaining its strength. Keeping in contact with magnetic world we’ve become to depend on.
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Revolution and a revolution…
Magnetism is more than an invisible force protecting the earth and guiding its inhabitants. Together with the electricity, magnetism ignited the machine age and created the modern world.
“ The electricity and magnetism were used to make motors run, to make video-tapes work, to use in cars and stereos. They are part of our world. If you choose not to know about something like that, they will become magic.”
---------- Steve Fairfax. Chief engineer Plasma Fusion Center, MIT
Understanding what seem to be the magical link between the electricity and magnetism began with the observation. When ships are hit by lightening, compasses on a board swing a while. In 1920s, a Dane named Hans Christian Osterd, recreated this natural phenomenon in his laboratory. He placed a compass near a wire attached to a battery, as the electric current flew through the wire, the compass needle kicked. Osterd had shown that the electric current generated a magnetic field. In England, Michael Farady(法拉第)took Osterd’s work a giant step further.
His 40-year study of electro-magnetism would bring about a technical revolution. First Farady show that a wire placed next to magnet rotates when an electric current flows through the wire. That was the beginning of the electric motor……
“ He got it…… We have a motor.”
Years later Farady made his second discovery. He found that moving a magnet in and out a coil of water created an electric current in the wire. That was the beginning of the electric generator. Now mechanical energy could be converted into electric energy and electric energy into mechanical energy. A new world dawn. The pray began.
“Magnetism, the poor old work horse, just keep going alone. Magnetism is involved in motors and all kinds of machinery. It is involved in that electric generator as the plant you can see in distance there. That is producing electricity by using magnetic induction basically. So magnetism is not rare in our world, far from it, it is ever present.”
It is a set of major motion picture, and you see how present it is.
“ OK, how about the car. We like a car…….”
“ Are you sitting now……”
“ No I am standing up, standing up right now.”
We have passed from the machine age to the information age, another technological revolution, brought to you by magnetism.
“Get ready, please. We are rolling. Action……”
Magnets in the camera motor move the film. Earphones have magnets that move little metal diaphragm to reproduced sound. The picture on video-monitor is painted by electron beam, controlled by a magnet. The computer stores its bits and bytes on a magnetic disc. A magnet in a record-head stores audio-information.
“ It is interesting to reflect them on the fact that one tea-spoonful of a rusty powder coated onto the floppy discs and video-tape can store more information than all the clave tablets in ancient Egypt.”
Video-tape, computer discs and video-cassettes all store information magnetically.
But data storage is not magnetism’s only contribution to the information age. Electronic magnetic waves enable us to transmit these data all over the world.
“ The most important single function of magnetism is it can transport energy through universe, into the field of radiation from the sun if they are under electronic waves to transmit.”
-------Henry Kolm, physicist, Magneplane International
Electronic and magnetic fields that vibrate right angles to each other, created the waves that transport radio and television signal through space, even light travel in an form of electron-magnetic wave.
“ So light is a vibration where the changing electric party induces magnetic part, which induces magnetic part….. and whole thing keeps inventing itself. Moving outward and in a light that was coming out of the sun. That is electro-magnetism that is coming to us.”
The unified force of electron-magnetism makes the motor run, also transport light and energy that sustains life on the earth.
A magnetic journey……
Picture: “ The nation that controls magnetism will control the universe.”
Magnetism had made our modern world possible, but the journey is not over,
“Silence, now the race is about ready to begin.”
“Wait, wait, wait……”
“ Are you right? It said, go……”
When you ride into the 21st century, we maybe do it all on the magnet. This is no ordinary train. It is a magnetic levitation vehicle known as MAGLEV, a machine that uses magnets to fly. Put 2 mode-ends of magnets together, and they are pushed apart. The force that propels to a car can also lift the 50-ton MAGLEV of their tracks. Strong magnets in the vehicle induce repelling force in aluminum track, just as your face is reflected in the mirror.
“ There is no interaction between the interaction between the magnet and aluminum, because aluminum is not magnetic. But when the aluminum is moving, that it produces a very strong reposing force on the aluminum. That is because the magnet induces an image of itself in the aluminum, and that it seizes a magnet of alike polarity, north pole. See, it is in North Pole and repels.”
So the repelling magnets lift MAGLEV 6 feet off its track. But what propels the vehicle forward? Attraction and propulsion.
Alternated magnetic fields in the track interact with the vehicle to move the flowing MAGLEV forward at up to 300 miles an hour.
If all this seems vaguely familiar, maybe it is because floating vehicle has become stable in science fiction for decades.
And real-life MAGLEV happens around as all. In New York, 1914, Elin Bachley patented the very first magnet MAGLEV. It worked so well, and it crashed through the wall of his laboratory. Since Bachley, Herry Kolm and other have perfected their own MAGLEV designs. With vehicles already on track in Germany and Japan, Americans, like Kolm, are waiting ready to see if their MAGLEV will fly.
“ Magnetism has already revolutionized our society in many ways. It is waiting in the wings to do new things.”
They are doing new thing at the MIT magnetic lab, using magnetism to create energy from water.
If you split uranium(铀) atoms, some of its mass is converted into energy, lots of energy. This is nuclear fusion. You can also make energy by squeezing atoms together. Fuels 2 hydrogen atoms and you can get one helium(氦) atom, plus energy. This is nuclear fusion. At MIT, they are using magnets to create energy from fusion.
“If you know the way of healing atom, and you made, and compare ways of 2 hydrogen atoms when into reaction, you will find the helium weight a little bit less and that small difference in mass is converted into huge energy by the famous equation “E=MC2”. E is the energy; M is the changed mass from 2 hydrogen atoms to 1 helium; C is the number which represents the speed of light, which 186,000 miles per second. C2 is that the speed is multiplied by itself. It is an unimaginable huge of number, so its extremely tiny difference of mass releases a tremendous amount of energy. And that what fusion is.”
And that is what keeps the sun burning. But if you catch a little bit of the sun, what could you keep it then? The answer is magnetism, a magnetic bottle.
Steve Fairfax is the chief engineer of MIF’s Plasma Fusion Reacctor, the TOCOMAC. He is the keeper of the bottle.
“We set the power for a medium-sized city through this 5-foot concrete walls. And owing to the magnets of the TOCOMAC, for we use it to produce a very powerful magnetive field. Inside the TOCOMAC, we got a heat of gas with 50 million degrees and the center of sun is only about 15 million degrees. And there is no material on the planet of earth could stand the temperature, even 1 million, so we make magnetic field and create magnetive bottle. That holds plasma waves away form the machine.”
At MIT, they use 15,000 gallon of liquid nitrogen(液化氮) every day to cool their electronic magnets to 350 degrees below zero. Once cooled, they can send huge pulses of energy through magnets and into the TOCOMAC.
“Magnetic forces are so great that it would lift a stack of cars as high as Mount Everest. And it takes a hundred bolts, like this to keep the machine from flying apart.”
Inside the machine’s donate-shaped chamber, gases are heated until the atoms lose their electrons and the gas becomes the plasmas.
Because it is too heat to see inside the TOCOMAC, Fairfax has a model that shows how magnetic field are used to induce fusion.
“ Now, if I take this horse magnet and put it next to the plasma, you can see that magnetic fields from this magnet are having a very strong effect on the plasmas that can move it around. Now we don’t use horse magnetism in our research, we use electric magnet like this, so when we turned on that now, you can see the plasma cools and squeezes away from the wall of the tube, because it not touching tube anymore. The plasma is hotter, it is also not being cooled much by touching the tube, and that makes it brighter. So this is the very same principle we are using in and our machine only where these plasmas are only 5,000 degrees, in our machine where shooting for temperature of 50 million degrees.”
TOCOMAC now acquires more energy than it produces by fusion. But when they reach 15 million degrees, they will be one step closer to producing power to light the world, power to replace fossil fuels. Cheap power.
“ It means that, if we will have a mean to distract power from sea water, without causing pollution in the form of radioactive fuel elements that has to be disposed off. They will produce nothing, but pure energy and light. That’s the dream.”
