Physics of the Future

by Michio Kaku

  Up to 30 percent of the electricity generated by an electrical plant can be wasted in the transmission. Room temperature superconducting wires could change all that, thereby saving significantly on electrical costs and pollution. This could also have a profound impact on global warming. Since the world’s production of carbon dioxide is tightly connected to energy use, and since most of that energy is wasted to overcome friction, the age of magnetism could permanently reduce energy consumption and carbon dioxide production.

  THE MAGNETIC CAR AND TRAIN

  Without any extra input of energy, room temperature superconductors could produce supermagnets capable of lifting trains and cars so they hover above the ground.

  One simple demonstration of this power can be done in any lab. I’ve done it several times myself for BBC-TV and the Science Channel. It’s possible to order a small piece of ceramic high-temperature superconductor from a scientific supply company. It’s a tough, gray ceramic about an inch in size. Then you can buy some liquid nitrogen from a dairy supply company. You place the ceramic in a plastic dish and gently pour the liquid nitrogen over it. The nitrogen starts to boil furiously as it hits the ceramic. Wait until the nitrogen stops boiling, then place a tiny magnet on top of the ceramic. Magically, the magnet floats in midair. If you tap the magnet, it starts to spin by itself. In that tiny dish, you may be staring at the future of transportation around the world.

  The reason the magnet floats is simple. Magnetic lines of force cannot penetrate a superconductor. This is the Meissner effect. (When a magnetic field is applied to a superconductor, a small electric current forms on the surface and cancels it, so the magnetic field is expelled from the superconductor.) When you place the magnet on top of the ceramic, its field lines bunch up since they cannot pass through the ceramic. This creates a “cushion” of magnetic field lines, which are all squeezed together, thereby pushing the magnet away from the ceramic, making it float.

  Room temperature superconductors may also usher in an era of supermagnets. MRI machines, as we have seen, are extremely useful but require large magnetic fields. Room temperature superconductors will allow scientists to create enormous magnetic fields cheaply. This will allow the future miniaturization of MRI machines. Already, using nonuniform magnetic fields, MRI machines about a foot tall can be created. With room temperature superconductors, it might be possible to reduce them to the size of buttons.

  In the movie Back to the Future Part III, Michael J. Fox was filmed riding a hoverboard, a skateboard that floated in air. After the movie debut, stores were flooded with calls from kids asking to purchase the hoverboard. Unfortunately, hoverboards do not exist, but they might become possible with room temperature superconductors.

  MAGLEV TRAINS AND CARS

  One simple application of room temperature superconductors is to revolutionize transportation, introducing cars and trains that float above the ground and thus move without any friction.

  Imagine riding in a car that uses room temperature superconductors. The roads would be made of superconductors instead of asphalt. The car would either contain a permanent magnet or generate a magnetic field via a superconductor of its own. The car would float. Even compressed air would be enough to get the car going. Once in motion, it would coast almost forever if the road were flat. An electric engine or jet of compressed air would be necessary only to overcome air friction, which would be the only drag that the car faces.

  Even without room temperature superconductors, several nations have produced magnetic levitating trains (maglev) that hover above a set of rails containing magnets. Since the north poles of magnets repel other north poles, the magnets are arranged so that the bottom of the train contains magnets that allow them to float just above the tracks.

  Room-temperature superconductors may one day give us flying cars and trains. These may float on rails or over superconducting pavement, without friction. (photo credit 5.3)

  Germany, Japan, and China are leaders in this technology. Maglev trains have even set some world records. The first commercial maglev train was the low-speed shuttle train that ran between Birmingham International Airport and Birmingham International Railway Station in 1984. The highest recorded maglev speed was 361 miles per hour, recorded in Japan on the MLX01 train in 2003. (Jet airplanes can fly faster, partly because there is less air resistance at high altitudes. Since a maglev train floats in air, most of its energy loss is in the form of air friction. However, if a maglev train were operating in a vacuum chamber, it might travel as fast as 4,000 miles per hour.) Unfortunately, the economics of maglev trains has prevented them from proliferating around the world. Room temperature superconductors might change all that. This could also revitalize the rail system in the United States, reducing the emission of greenhouse gases from airplanes. It is estimated that 2 percent of greenhouse gases come from jet engines, so maglev trains would reduce that amount.

  ENERGY FROM THE SKY

  By the end of the century, another possibility opens up for energy production: energy from space. This is called space solar power (SSP) and involves sending hundreds of space satellites into orbit around the earth, absorbing radiation from the sun, and then beaming this energy down to earth in the form of microwave radiation. The satellites would be based 22,000 miles above the earth, where they become geostationary, revolving around the earth as fast as the earth spins. Because there is eight times more sunlight in space than on the surface of the earth, this presents a real possibility.

  At present, the main stumbling block to SSP is cost, mainly that of launching these space collectors. There is nothing in the laws of physics to prevent collecting energy directly from the sun, but it is a huge engineering and economic problem. But by end of the century, new ways of reducing the cost of space travel may put these space satellites within reach, as we will see in Chapter 6.

  The first serious proposal for space-based solar power was made in 1968, when Peter Glaser, president of the International Solar Energy Society, proposed sending up satellites the size of a modern city to beam power down to the earth. In 1979, NASA scientists took a hard look at his proposal and estimated that the cost would be several hundred billion dollars, which killed the project.

  But because of constant improvements in space technology, NASA continued to fund small-scale studies of SSP from 1995 to 2003. Its proponents maintain that it is only a matter of time before the technology and economics of SSP make it a reality. “SSP offers a truly sustainable, global-scale and emission-free electricity source,” says Martin Hoffert, a physicist formerly at New York University.

  There are formidable problems facing such an ambitious project, real and imaginary. Some people fear this project because the energy beamed down from space might accidentally hit a populated area, creating massive casualties. However, this fear is exaggerated. If one calculates the actual radiation hitting the earth from space, it is too small to cause any health hazard. So visions of a rogue space satellite sending death rays down to earth to fry entire cities is the stuff of a Hollywood nightmare.

  Science fiction writer Ben Bova, writing in the Washington Post in 2009, laid out the daunting economics of a solar power satellite. He estimated that each satellite would generate 5 to 10 gigawatts of power, much more than a conventional coal-fired plant, and cost about eight to ten cents per kilowatt-hour, making it competitive. Each satellite would be huge, about a mile across, and cost about a billion dollars, roughly the cost of a nuclear plant.

  To jump-start this technology, he asked the current administration to create a demonstration project, launching a satellite that could generate 10 to 100 megawatts. Hypothetically, it could be launched at the end of President Obama’s second term in office if plans are started now.

  Echoing these comments was a major initiative announced by the Japanese government. In 2009, the Japanese Trade Ministry announced a plan to investigate the feasibility of a space power satellite system. Mitsubishi Electric and other Japanese companies will join a $10 billion
program to perhaps launch a solar power station into space that will generate a billion watts of power. It will be huge, about 1.5 square miles in area, covered with solar cells.

  “It sounds like a science fiction cartoon, but solar power generation in space may be a significant alternative energy source in the century ahead as fossil fuel disappears,” said Kensuke Kanekiyo of the Institute of Energy Economics, a government research organization.

  Given the magnitude of this ambitious project, the Japanese government is cautious. A research group will first spend the next four years studying the scientific and economic feasibility of the project. If this group gives the green light, then the Japanese Trade Ministry and the Japanese Aerospace Exploration Agency plan to launch a small satellite in 2015 to test beaming down energy from outer space.

  The major hurdle will probably not be scientific but economic. Hiroshi Yoshida of Excalibur KK, a space consulting company in Tokyo, warned, “These expenses need to be lowered to a hundredth of current estimates.” One problem is that these satellites have to be 22,000 miles in space, much farther than satellites in near-earth orbits of 300 miles, so losses in transmission could be huge.

  But the main problem is the cost of booster rockets. This is the same bottleneck that has stymied plans to return to the moon and explore Mars.

  Unless the cost of rocket launches goes down significantly, this plan will die a quiet death.

  Optimistically, the Japanese plan could go operational by midcentury. However, given the problems with booster rockets, more likely the plan will have to wait to the end of the century, when new generations of rocket drive down the cost. If the main problem with solar satellites is cost, then the next question is: Can we reduce the cost of space travel so that one day we might reach the stars?

  We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars.

  —CARL SAGAN

  In powerful chariots, the gods of mythology roamed across the heavenly fields of Mount Olympus. On powerful Viking ships, the Norse gods sailed across the cosmic seas to Asgard.

  Similarly, by 2100, humanity will be on the brink of a new era of space exploration: reaching for the stars. The stars at night, which seem so tantalizingly close yet so far, will be in sharp focus for rocket scientists by the end of the century.

  But the road to building starships will be a rocky one. Humanity is like someone whose outstretched arms are reaching for the stars but whose feet are mired in the mud. On one hand, this century will see a new era for robotic space exploration as we send satellites to locate earthlike twins in space, explore the moons of Jupiter, and even take baby pictures of the big bang itself. However, the manned exploration of outer space, which has enthralled many generations of dreamers and visionaries, will be a source of some disappointment.

  EXTRASOLAR PLANETS

  One of the most stunning achievements of the space program has been the robotic exploration of outer space, which has vastly expanded the horizon of humanity.

  Foremost among these robotic missions will be the search for earthlike planets in space that can harbor life, which is the holy grail of space science. So far, ground-based telescopes have identified about 500 planets orbiting in distant star systems, and new planets are being discovered at the rate of one planet every one to two weeks. The big disappointment, however, is that our instruments can identify only gigantic, Jupiter-sized planets that cannot sustain life as we know it.

  To find planets, astronomers look for tiny wobbles in the path of a star. These alien solar systems can be likened to a spinning dumbbell, where the two balls revolve around each other; one end represents the star, clearly visible by telescope, while the other represents a Jupiter-sized planet, which is about a billion times dimmer. As the sun and Jupiter-sized planet spin around the center of the dumbbell, telescopes can clearly see the star wobbling. This method has successfully identified hundreds of gas giants in space, but it is too crude to detect the presence of tiny, earthlike planets.

  The smallest planet found by these ground-based telescopes was identified in 2010 and is 3 to 4 times as massive as earth. Remarkably, this “superearth” is the first one to be in the habital zone of its sun—i.e., at the right distance to have liquid water.

  All this changed with the launch of the Kepler Mission telescope in 2009 and the COROT satellite in 2006. These space probes look for tiny fluctuations in starlight, caused when a small planet moves in front of its star, blocking its light by a minuscule amount. By carefully scanning thousands of stars to look for these tiny fluctuations, the space probes will be able to detect perhaps hundreds of earthlike planets. Once identified, these planets can be quickly analyzed to see if they contain liquid water, perhaps the most precious commodity in space. Liquid water is the universal solvent, the mixing bowl where the first DNA probably got off the ground. If liquid-water oceans are found on these planets, it could alter our understanding of life in the universe.

  Journalists in search of a scandal say, “Follow the money,” but astronomers searching for life in space say, “Follow the water.”

  The Kepler satellite, in turn, will be replaced by other, more sensitive satellites, such as the Terrestrial Planet Finder. Although the launch date for the Terrestrial Planet Finder has been postponed several times, it remains the best candidate to further the goals of Kepler.

  The Terrestrial Planet Finder will use much better optics to find earthlike twins in space. First, it will have a mirror four times larger and one hundred times more sensitive than that of the Hubble Space Telescope. Second, it will have infrared sensors that can nullify the intense radiation from a star by a factor of a million times, thereby revealing the presence of the dim planet that may be orbiting it. (It does this by taking two waves of radiation from the star and then carefully combining them so that they cancel each other out, thereby removing the unwanted presence of the star.)

  So in the near future, we should have an encyclopedia of several thousand planets, of which perhaps a few hundred will be very similar to the earth in size and composition. This, in turn, will generate more interest in one day sending a probe to these distant planets. There will be an intense effort to see if these earthlike twins have liquid-water oceans and if there are any radio emissions from intelligent life-forms.

  EUROPA—OUTSIDE THE GOLDILOCKS ZONE

  There is also another tempting target for our probes within our solar system: Europa. For decades, it was believed that life in the solar system can exist only in the “Goldilocks zone” around the sun, where planets are not too hot or too cold to sustain life. The earth is blessed with liquid water because it orbits at the right distance from the sun. Liquid water will boil on a planet like Mercury, which is too close to the sun, and will freeze on a planet like Jupiter, which is too far. Since liquid water is probably the fluid in which DNA and proteins were first formed, it was long believed that life in the solar system can exist only on earth, or perhaps Mars.

  But astronomers were wrong. After the Voyager spacecraft sailed past the moons of Jupiter, it became apparent that there was another place for life to flourish: under the ice cover of the moons of Jupiter. Europa, one of the moons of Jupiter discovered by Galileo in 1610, soon caught the attention of astronomers. Although its surface is permanently covered with ice, beneath that ice there is a liquid ocean. Because the ocean is much deeper on Europa than on earth, the total volume of the Europan ocean is estimated to be twice the volume of earth’s oceans.

  This was a bit of a shock, realizing that there is an abundant energy source in the solar system other than the sun. Underneath the ice, the surface of Europa is continually heated by tidal forces. As Europa tumbles in its orbit around Jupiter, that massive planet’s gravity squeezes the moon in different directions, creating friction deep within its core. This friction creates heat, which in turn melts the ice and creates a stable ocean of liquid water.

  This discovery means that perhaps the moons of distant
gas giants are more interesting than the planets themselves. (This is probably one reason James Cameron chose a moon of a Jupiter-size planet for the site of his 2009 movie, Avatar.) Life, which was once thought to be quite rare, might actually flourish in the blackness of space on the moons of distant gas giants. Suddenly, the number of places where life might flourish has exploded by many times.

  As a consequence of this remarkable discovery, the Europa Jupiter System Mission (EJSM) is tentatively scheduled for launch in 2020. It is designed to orbit Europa and possibly land on it. Beyond that, scientists have dreamed of exploring Europa by sending even more sophisticated machinery. Scientists have considered a variety of methods to search for life under the ice. One possibility is the Europa Ice Clipper Mission, which would drop spheres on the icy surface. The plume and debris cloud emerging from the impact site would then be carefully analyzed by a spacecraft flying through it. An even more ambitious program is to put a remote-control hydrobot submarine beneath the ice.

  Interest in Europa has also been stoked by new developments under the ocean here on earth. Until the 1970s, most scientists believed that the sun was the only energy source that could make life possible. But in 1977, the Alvin submarine found evidence of new life-forms flourishing where no one suspected before. Probing the Galapagos Rift, it found giant tube worms, mussels, crustaceans, clams, and other life-forms using the heat energy from volcano vents to survive. Where there is energy, there might be life; and these undersea volcano vents have provided a new source of energy in the inky blackness of the sea floor. In fact, some scientists have suggested that the first DNA was formed not in some tide pool on the earth’s coast but deep undersea near a volcano vent. Some of the most primitive forms of DNA (and perhaps the most ancient) have been found on the bottom of the ocean. If so, then perhaps volcano vents on Europa can provide the energy to get something like DNA off the ground.