Navtej kohli Los Angeles

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Navtej kohli Los Angeles

  1. 1. Knowledge Sharing Session Welcome aboard !! A safe return to the Earth is guaranteed
  2. 2. How many of you have watched this Sci-fi movie ?
  3. 3. What are the two major themes in the movie ?
  4. 4. - The first is exploitation of natural resources by a large corporation - The second is concept of teleportation Today’s topic deals with the second theme and other similar concepts
  5. 5. And what is the theme of this movie ? But before we move ahead, How many of you’ve seen this movie ?
  6. 6. So, I’ll also make my presentation without any complex equations.
  7. 7. Do you think any of these things is possible? <ul><li>Floating in air </li></ul><ul><li>Invisibility </li></ul><ul><li>Teleportation </li></ul><ul><li>Travelling faster than light </li></ul><ul><li>Time Travel </li></ul>
  8. 8. Before we rule out these as impossible, think back 100 years to those technological advances that were declared ‘impossible’ by scientists at that time and that have now become part of our every day lives. - Lord Kelvin (perhaps the most prominent scientist of the Victorian era) declared that ‘heavier than air’ devices such as the airplane were impossible. He also thought that X-rays were a hoax and that Radio had no future. - Lord Rutherford dismissed the possibility of building an atomic bomb, comparing it to ‘moonshine’. - Robert Goddard, the father of modern rocketry was ridiculed by New York Times editors in 1921 who thought that Rockets could never travel in outer space. They claimed that Prof. Goddard seems to lack the basic knowledge ladled out daily in High Schools.
  9. 9. On the other hand, Jules Verne (a great sci-fi writer) wrote a novel in 1863, Paris in the Twentieth Century , which was locked away and forgotten for over a century until it was accidentally discovered by his great-grandson and published for the first time in 1994. In it Verne predicted what Paris might look like in the year 1960. His novel was filled with technology that was clearly considered impossible in the 19 th century, including fax machines, a world-wide communication network, glass skyscrapers , gas powered automobiles and high-speed elevated trains. Thus ‘impossible’ is a relative term. Time and again we see that the study of the impossible has opened up entirely new vistas , pushing the boundaries of physics and chemistry and forcing scientists to redefine what they mean by impossible. The purpose of today’s discussion is to consider what technologies are considered ‘impossible’ today that might well become commonplace decades to centuries down the road.
  10. 10. The things that are ‘impossible’ today can be divided into three categories: Class I impossibilities - These are technologies that are impossible today but that do not violate the known laws of physics. So they might be possible in this century, or perhaps the next, in modified form. Ex. teleportation, invisibility and certain forms of telepathy. Class II impossibilities – These are technologies that sit at the very edge of our understanding of the physical world. They might be realized thousands of years in the future. They include time machines, the possibility of hyperspace travel, and travel through wormholes. Class III impossibilities – These are technologies that violate the known laws of physics. Surprisingly, there are very few such impossible technologies. Perpetual motion machine and precognition (seeing the future) may come under this category.
  11. 11. Magnetic Levitation In science fiction, magnetic force fields serve as a platform to defy gravity. In the movie Back to the Future, Michael J. Fox rides a ‘hoverboard’, which resembles a skateboard except that it floats over the street. Such an antigravity device is impossible given the laws of physics as we know them today but magnetically enhanced hover boards and hover cars could become reality in the future, giving us the ability to levitate large objects at will. In the future, if ‘room temperature superconductors’ become a reality, one might be able to levitate large objects using the power of magnetic force fields.
  12. 12. Magnetic Levitation If we place two bar magnets next to each other with north poles opposite each other, the two magnets repel each other. This same principle can be used to lift enormous weights off the ground. Already several nations are building advanced magnetic levitation trains (maglev trains) that hover just above the railroad tracks using ordinary magnets. Because they have zero friction, they can attain very high speeds, floating over a cushion of air. But these maglev devices are extremely expensive. Another way to increase efficiency would be to use superconductors, which lose all electrical resistance when they are cooled down to near absolute zero. Superconductors can even be used to transmit electrical power almost for free. Magnets of incredible power could be made which can lift huge loads with ease.
  13. 13. Concept
  14. 14. Room temperature superconductors <ul><li>Despite all these miraculous powers, the problem with superconductivity is that it is </li></ul><ul><li>very expensive to immerse large magnets in vats of supercooled liquid, making </li></ul><ul><li>superconducting magnets prohibitively expensive. </li></ul><ul><li>But one day physicists may be able to create a ‘room temperature superconductor’. </li></ul>Then powerful magnetic fields capable of lifting cars and trains would become so cheap that hover cars might become economically feasible. With room temperature superconductors, the flying cars seen in Back to the Future might become a reality. We even may be able to wear a belt made of superconducting magnets that would enable us to effortlessly levitate off the ground. With such a belt, one could fly in the air like Superman. The concept behind this is a common property of superconductivity, called the Meissner effect. If you place a magnet above a superconductor, the magnet will levitate, as if held upward by a some invisible force. The reason is that the magnet creates a ‘mirror image’ and they repel each other.
  15. 15. Invisibility Invisibility has long been one of the marvels of science fiction and fantasy. Yet for at least a century, physicists have dismissed the possibility of invisibility cloaks, stating flatly that they are impossible: they violate the laws of optics and do not confirm to any of the known properties of matter. Invisibility is a property that arises at the atomic level and hence would be exceedingly difficult to, if not impossible to duplicate using ordinary means. The military, unable to create invisible airplanes, has tried to do the next best thing: create stealth technology, which renders airplanes invisible to radar. Even with stealth technology, a jet fighter is not totally invisible, rather it deflects and disperses as much radar as possible. But perhaps the most promising new development involving invisibility is an exotic new material called a ‘metamaterial’ which may one day render objects truly invisible. Ironically, the creation of metamaterials was once thought to be impossible because they violate the laws of optics. But in 2006, researchers at Duke University defied conventional wisdom and used metamaterials to make an object invisible to microwave radiation. Although, there are still many hurdles to overcome, for the first time in history we now have a blue print to render ordinary objects invisible.
  16. 16. Invisibility Metamaterials are substances that have optical properties not found in nature. At the heart of metamaterials is their ability to manipulate something called the ‘index of refraction’. Refraction is the bending of light. If you put your hand in water, you notice that water distort and bend the path of ordinary light. In a metamaterial, light could bend and meander in new directions, creating a path that would wander throughout the substance like a snake. If a metamaterial has a negative index of refraction, the object would become invisible. Now the goal is to use nanotechnology to create metamaterials that can bend visible light, not just microwaves. With breakthroughs occuring in this field every few months, some physicists see some sort of practical invisibility shield emerging out of the laboratory perhaps within a few decades. Holograms: Another way to render a person partially invisible is to photograph the scenery behind a person and then project that background image directly onto the person’s clothes or onto a screen in front of him. As seen from the front, it appears as if the person has become transparent, that light has somehow passed right through the person’s body.
  17. 17. Concept of optical camouflage Though the technical problems with holographic invisibility are formidable, within this century a form of invisibility may become commonplace.
  18. 18. Teleportation Teleportation, or the ability to transport a person or object instantly from one place to another, is a technology that could change the course of civilization and alter the destiny of nations. Today’s transportation system- from cars to airplanes and railroads would become obsolete; we would simply teleport ourselves to work and our goods to market. Vacations would become effortless, as we teleport ourselves to our destination. Teleportation would change everything. According to Newton’s theory, teleportation is clearly impossible. Objects do not move until they are pushed; objects do not suddenly disappear and reappear somewhere else. But in the quantum theory, that’s precisely what particles can do. At the quantum level, all the basic laws of common sense are violated: electrons can disappear and reappear elsewhere, and electrons can be many places at the same time. (In Hindu Mythology, Krishna’s Rasleela alludes to the same phenomenon.) The fact that electrons can seemingly be many places at the same time forms the very basis of chemistry and it is this sharing of electrons between two atoms that holds the molecules of our body together. Without quantum theory, our molecules and atoms would dissolve instantly.
  19. 19. Teleportation Progress in Teleportation is rapidly accelerating. In 2007, physicists made a breakthrough. They took a beam of rubidium atoms, converted all its information into a beam of light, sent this beam of light across a fibre-optic cable, and then reconstructed the original beam of atoms in a distant location. If this experiment can be replicated, it will open up new ways to teleport increasingly large objects. The key to this type of teleportation is a new state of matter called a ’Bose Einstein Condensate’ or BEC, which is one of the coldest substances in the entire universe. Though BEC is quite difficult to create in the laboratory, the properties of BECs are quite peculiar and the bizarre quantum effects that we see only at the atomic level can be seen with the naked eye with a BEC. Given the progress we have made, when we might be able to teleport ourselves ? Physicists hope to teleport complex molecules in the coming years. After that perhaps a DNA molecule or even a virus may be teleported within decades. There is nothing in principal to prevent teleporting an actual person, just as in the sci-fi movies like Avatar , but the technical problems facing such a feat are truly staggering. In fact, it will likely take many centuries before everyday objects could be transported.
  20. 20. Travelling faster than light In Einstein’s general theory of relativity, space-time is a fabric that can stretch and shrink. Under certain circumstances, the fabric may stretch faster than speed of light. It can also allow for ‘holes in space’ in which one can take short cuts through space and time. <ul><li>There are two ways in which travel faster than light might be done: </li></ul><ul><li>Stretching space- If you were to stretch the space behind you and contract the space in front of you, then you would have the illusion of having moved faster than light. Since space has been deformed, it means you can reach the distant stars in an instant. </li></ul><ul><li>Ripping space- in 1935, Einstein introduced the concept of wormhole. The wormhole is a device that can connect two universes. </li></ul>
  21. 21. Concept The Alcubierre Drive Travelling faster than light
  22. 22. Time Travel All of us have at sometime wondered about the strange nature of time and how it differs from space. If we can move forward and backward in space, why not in time? All of us have also wondered what the future may hold for us. From the perspective of science, time travel was impossible in Newton’s universe, where time was seen as an arrow. Once fired, it could never deviate from its past. One second on Earth was one second throughout the universe. This concept was overthrown by Einstein, who showed that time was more like a river, speeding up and slowing down as it snaked across stars and galaxies. So one second on the Earth is not absolute; time varies when we move around the universe. According to Einstein’s special theory of relativity, time slows down inside a rocket the faster it moves. Sci-fi writers have speculated that if you could break the light barrier, you could go back in time. But this is not possible as the speed of light is the ultimate barrier for any rocket. Or may be not… Nonetheless, time travel to the future is possible, and has been experimentally verified. If an astronaut were to travel near the speed of light, it might take him, say one minute to reach the nearest stars. Four years would have elapsed on the Earth, but for him only one minute would have passed, because time would have slowed down inside the rocket ship. Hence he would have travelled four years into the future, as experienced here on Earth. So a time machine that can take us into the future is consistent with Einstein’s special theory of relativity. But what about going backward in time ?
  23. 23. Concept of Time Machine The latest concept of time machine involves a ‘transversable wormhole’. Since space and time are intimately intertwined in Einstein’s theory, a wormhole can connect two points in time. By falling down the wormhole, you could journey into the past or in the future. There are formidable problems facing this design and you would be able to go back in time only to the point when the time machines were built.
  24. 24. Epilogue Are there truths that will be forever beyond our grasp ? Are there realms of knowledge that will be out side the capabilities of even an advanced civilization? Of all the technologies mentioned so far, only perpetual motion machines and precognition fall into the category of class III impossibilities. Are there other technologies that are simply impossible ? Today some scientists are raising a new set of impossibilities: we will never know what happened before the birth of the universe or why the ‘Big bang’ took place at all. To sum up, there will always be things that are beyond our grasp, that are impossible to explore. But the coming years in physics could be the most exciting of all, as we explore the universe with a new generation of particle accelerators, space-based gravity wave detectors, and other technologies. Thus we are not at the end, but at the beginning of a new physics.
  25. 25. Further readings A brief history of time –Stephen Hawking Black holes and baby universes – Stephen Hawking Hyperspace – Michio Kaku
  26. 26. Thank you

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