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58-417: A force field confined to a Collimated beam with clean borders is one of the principal characteristics of tractor and repulsor beams. Several theories that have predicted that repulsive effects do not fall within the category of tractor and repulsor beams because of the absence of field collimation. For example, Robert L. Forward of Hughes Research Laboratories showed that general relativity theory allowed

116-496: A microtome , placed in a freezer. The cryostat is usually a stationary upright freezer, with an external wheel for rotating the microtome. The temperature can be varied, depending on the tissue being cut usually from −20 °C to −30 °C. The freezer is either powered by electricity, or by a refrigerant like liquid nitrogen. Small portable cryostats are available and can run off generators or vehicle inverters. To minimize unnecessary warming all necessary mechanical movements of

174-513: A bubble of charged plasma , contained by a fine mesh of superconducting wire, to surround a spacecraft. This would protect the spacecraft from interstellar radiation and some particles without needing physical shielding . The Rutherford Appleton Laboratory was in 2007 attempting to design an actual test satellite, which would orbit Earth with a charged plasma field around it. In 2008, Cosmos Magazine reported on research into creating an artificial replica of Earth's magnetic field around

232-403: A chamber through which cold helium vapour is pumped. An external mechanical refrigerator extracts the warmer helium exhaust vapour, which is cooled and recycled. Closed-cycle cryostats consume a relatively large amount of electrical power, but need not be refilled with helium and can run continuously for an indefinite period. Objects may be cooled by attaching them to a metallic cold plate inside

290-614: A few characters have the explicit ability to create force fields (for example, the Invisible Woman of the Fantastic Four and Violet Parr from The Incredibles ), it has been emulated via other powers, such as Green Lantern 's energy constructs, Jean Grey 's telekinesis, and Magneto's manipulation of electromagnetic fields. Apart from this, its importance is also highlighted in Dr. Michio Kaku 's books (such as Physics of

348-468: A frequent superpower in superhero media . While sometimes an explicit power on their own, force fields have also been attributed to other fictional abilities. Marvel Comics' Jean Grey is able to use her telekinesis to create a barrier of telekinetic energy that acts as a force field by repelling objects. Similarly, Magneto is able to use his magnetism to manipulate magnetic fields into acting as shields. The most common superpower link seen with force fields

406-415: A metal "chuck", and frozen to cutting temperature (for example at −20 °C). Once frozen, the specimen on the chuck is mounted on the microtome. The crank is rotated and the specimen advances toward the cutting blade. Once the specimen is cut to a satisfactory quality, it is mounted on a warm (room temperature) clear glass slide, where it will instantaneously melt and adhere. The glass slide and specimen

464-404: A new gravitational field, however, the device utilizes a doughnut-shaped Laguerre-Gaussian laser beam , which has a high-intensity ring of light that surrounds a dark core along the beam axis. This method confines particles to the center of the beam using photophoresis , whereby illuminated sections of the particle have a higher temperature and thus impart more momentum to air molecules incident on

522-405: A number of years investigating various configurations of particles delivery by light." Dr. Brzobohaty said: "These methods are opening new opportunities for fundamental photonics as well as applications for life-sciences." Dr Cizmar said: "Because of the similarities between optical and acoustic particle manipulation we anticipate that this concept will inspire exciting future studies in areas outside

580-404: A repulsive force field of gravitophotons could be produced by a ring rotating above a very strong magnetic field. Heim's theory, and its variants, have been treated by the mainstream scientific community as fringe physics. But the works by Forward, Dröscher, and Häuser could not be considered as a form of repulsor- or tractor-beam because the predicted impulses and field effects were not confined to

638-482: A research team from Tel-Aviv University, led by Dr. Alon Bahabad, experimentally demonstrated an optical analog of the Archimedes' screw where the rotation of a helical-intensity laser beam is transferred to the axial motion of optically trapped micrometer-scale, airborne, carbon-based particles. With this optical screw, particles were easily conveyed with controlled velocity and direction, upstream or downstream of

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696-645: A second body. In 1964, physicists Leopold Halpern of the Niels Bohr Institute and B. Laurent of the Nordic Institute for Theoretical Physics indicated general relativity theory and quantum theory allowed the generation and amplification of gravitons in a manner like the laser. They showed, in principle, gravitational radiation in the form of a beam of gravitons could be generated and amplified by using induced, resonant emissions. In 1992, Professor Yevgeny Podkletnov and R. Nieminen, of

754-471: A spacecraft to protect astronauts from dangerous cosmic rays . British and Portuguese scientists used a mathematical simulation to prove that it would be possible to create a " mini-magnetosphere " bubble several hundred meters across, possibly generated by a small uncrewed vessel that could accompany a future crewed mission to Mars. In 2014, a group of students from the University of Leicester released

812-464: A staple of many science-fiction works, so much so that authors frequently do not even bother to explain or justify them to their readers, treating them almost as established fact and attributing whatever capabilities the plot requires. The ability to create force fields has become a frequent superpower in superhero media . The concept of a force field goes back at least as far as early 20th century. The Encyclopedia of Science Fiction suggests that

870-405: A study describing functioning of spaceship plasma deflector shields. In 2015, Boeing was granted a patent on a force field system designed to protect against shock waves generated by explosions. It is not intended to protect against projectiles, radiation, or energy weapons such as lasers. The field purportedly works by using a combination of lasers, electricity and microwaves to rapidly heat

928-412: A tractor beam are usually attracted toward their common center of gravity. This means that if a small spaceship applies a tractor beam to a large object such as a planet, the ship will be drawn toward the planet, rather than vice versa. In Star Trek , tractor beams are imagined to work by placing a target in the focus of a subspace/graviton interference pattern created by two beams from an emitter. When

986-401: A vacuum chamber which is in thermal contact with the helium vapour chamber. Continuous-flow cryostats are cooled by liquid cryogens (typically liquid helium or nitrogen) from a storage dewar. As the cryogen boils within the cryostat, it is continuously replenished by a steady flow from the storage dewar. Temperature control of the sample within the cryostat is typically performed by controlling

1044-408: A well-defined, collimated region. The following are summaries of other notable experiments and theories that resemble repulsor and tractor beam concepts: In July 1960, trade magazine Missiles and Rockets reported that Martin N. Kaplan, a research engineer at Ryan Aeronautical Company , had conducted experiments that could lead to an ability to direct an anti-gravitational force toward or away from

1102-463: Is Florence Carpenter Dieudonné 's 1887 novel Rondah, or Thirty-Three Years in a Star , where the far-off Sun Island is enclosed by a "wall in the air" that blocks access by land, sea and air, which is occasionally disabled. In Isaac Asimov 's Foundation universe, personal shields have been developed by scientists specializing in the miniaturization of planet-based shields. As they are primarily used by Foundation Traders, most other inhabitants of

1160-416: Is a barrier produced by something like energy , negative energy , dark energy , electromagnetic fields , gravitational fields , electric fields , quantum fields , telekinetic fields , plasma , particles , radiation , solid light , magic , or pure force . It protects a person, area, or object from attacks or intrusions, or even deflects energy attacks back at the attacker. This fictional technology

1218-487: Is a device used to maintain low cryogenic temperatures of samples or devices mounted within the cryostat. Low temperatures may be maintained within a cryostat by using various refrigeration methods, most commonly using cryogenic fluid bath such as liquid helium . Hence it is usually assembled into a vessel, similar in construction to a vacuum flask or Dewar . Cryostats have numerous applications within science, engineering, and medicine. Closed-cycle cryostats consist of

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1276-411: Is created as a field of energy without matter that acts as a wall, so that objects affected by the particular force relating to the field are unable to pass through the field and reach the other side, instead being deflected or destroyed. Actual research in the 21st century has looked into the potential to deflect radiation or cosmic rays , as well as more extensive shielding. This concept has become

1334-421: Is placed in thermal contact with the liquid helium bath. The liquid helium may be replenished as it boils away, at intervals between a few hours and several months, depending on the volume and construction of the cryostat. The boil-off rate is minimised by shielding the bath with either cold helium vapour, or vacuum shield with walls constructed from super insulator material. The helium vapour which boils away from

1392-463: Is the power of invisibility . This is seen with Marvel Comics' Invisible Woman and Disney Pixar 's Violet Parr . Force fields often vary in what they are made of, though are commonly made of energy. The 2017 series The Gifted featured character Lauren Strucker who had the ability to create shields by pushing molecules together. This resulted in her being able to construct force fields out of air and water particles rather than energy. In 2005,

1450-498: The Galactic Empire do not know about this technology. In an unrelated short story Breeds There a Man...? by Asimov, scientists are working on a force field ("energy so channelled as to create a wall of matter-less inertia"), capable of protecting the population in case of a nuclear war. The force field demonstrated in the end is a solid hemisphere, apparently completely opaque and reflective from both sides. Asimov explores

1508-548: The NASA Institute for Advanced Concepts devised a way to protect from radiation by applying an electric field to spheres made of a thin, non-conductive material coated with a layer of gold with either positive or negative charges, which could be arranged to bend a stream of charged particles to protect from radiation. In 2006, a University of Washington group in Seattle , Washington, had been experimenting with using

1566-564: The Tampere University of Technology , discovered weight fluctuations in objects above an electromagnetically levitated, massive, composite superconducting disk. Three years later, Podkletnov reported the results of additional experiments with a toroidal disk superconductor. They reported the weight of the samples would fluctuate between −2.5% and +5.4% as the angular speed of the superconductor increased. Certain combinations of disk angular speeds and electromagnetic frequencies caused

1624-428: The shields function primarily as a defensive measure against weapons fired from other spacecraft. Force fields in these stories also generally prevent transporting . There are generally two kinds of force fields postulated: one in which energy is projected as a flat plane from emitters around the edges of a spacecraft and another where energy surrounds a ship like a bubble. The ability to create force fields has become

1682-532: The Impossible ). Science fiction and fantasy avenues suggest a number of potential uses of force fields: The capabilities and functionality of force fields vary; in some works of fiction (such as in the Star Trek universe), energy shields can nullify or mitigate the effects of both energy and particle (e.g., phasers ) and conventional weapons, as well as supernatural forces. In many fictional scenarios,

1740-437: The air creating a field of (ionised) superheated air-plasma which disrupts, or at least attenuates, the shock wave. As of March 2016, no working models were known to have been demonstrated. In 2016, Rice University scientists discovered that Tesla coils can generate force fields able to manipulate matter (process called teslaphoresis ). Cryostat A cryostat (from cryo meaning cold and stat meaning stable)

1798-442: The bath very effectively cools thermal shields around the outside of the bath. In the older designs there may be additional liquid nitrogen bath, or several concentric layers of shielding, with gradually increasing temperatures. However, the invention of super insulator materials has made this technology obsolete. In order to achieve temperatures lower than liquid helium at atmospheric pressure, additional cooler stages may be added to

Tractor beam - Misplaced Pages Continue

1856-462: The beam to its source. Tractor beams and pressor beams can be used together as a weapon: by attracting one side of an enemy spaceship while repelling the other, one can create severely damaging shear effects in its hull. Another mode of destructive use of such beams is rapid alternating between pressing and pulling force in order to cause structural damage to the ship as well as inflicting lethal forces on its crew. Two objects being brought together by

1914-507: The beams are manipulated correctly the target is drawn along with the interference pattern. The target may be moved toward or away from the emitter by changing the polarity of the beams. The range of the beam affects the maximum mass that the emitter can move, and the emitter subjects its anchoring structure to significant force. Force field (technology) In speculative fiction , a force field , sometimes known as an energy shield , force shield , energy bubble , or deflector shield ,

1972-436: The center) is capable of creating a pull-like effect on a given microscopic particle, forcing it toward the beam-source. The underlying physics is the maximization of forward scattering via interference of the radiation multipoles. They show explicitly that the necessary condition to realize a negative (pulling) optical force is the simultaneous excitation of multipoles in the particle. If the total photon momentum projection along

2030-524: The cryostat. Temperatures down to 1 K can be reached by attaching the cold plate to a 1-K pot , which is a container of the He-4 isotope that may be pumped to low vapor pressure via a vacuum pump. Temperatures just below 0.300 K may be achieved using He-3, the rare isotope of helium, as the working fluid in a helium pot. Temperatures down to 1 mK can be reached by employing dilution refrigerator or dry dilution refrigerator typically in addition to

2088-512: The field of photonics." Physicists from ANU built a reversible tractor beam, capable of transporting particles "one fifth of a millimetre in diameter a distance of up to 20 centimetres, around 100 times further than previous experiments." According to Professor Wieslaw Krolikowski, of the Research School of Physics and Engineering, "demonstration of a large scale laser beam like this is a kind of holy grail for laser physicists." The work

2146-602: The first use of the term in science fiction was in 1931, in Spacehounds of IPC by E.E. 'Doc' Smith . An early precursor of what is now called "force field" may be found in William Hope Hodgson 's The Night Land (1912), where the Last Redoubt, the fortress of the remnants of a far-future humanity, is kept safe by "The Air Clog" generated by the burning "Earth-Current". An even earlier precursor

2204-520: The flow rate of cryogen into the cryostat together with a heating wire attached to a PID temperature control loop . The length of time over which cooling may be maintained is dictated by the volume of cryogens available. Owing to the scarcity of liquid helium, some laboratories have facilities to capture and recover helium as it escapes from the cryostat, although these facilities are also costly to operate. Bath cryostats are similar in construction to vacuum flasks filled with liquid helium. A cold plate

2262-486: The fluctuations to stabilize at a 0.3% reduction. The experiments with the toroidal disk yielded reductions that reached a maximum of 1.9–2.1%. Reports about both sets of experiments stated the weight loss region was cylindrical, extending vertically for at least three meters above the disk. Qualitative observations of an expulsive force at the border of the shielded zone were reported in the Fall of 1995. Several groups around

2320-530: The force field concept again in the short story Not Final! . The concept of force fields as a defensive measure from enemy attack or as a form of attack can be regularly found in modern video games as well as in film, such as in The War of the Worlds (1953, George Pál) and Independence Day . The ability to create a force field has been a common superpower in comic books and associated media. While only

2378-441: The generation of a very brief impulse of a gravity-like repulsive force along the axis of a helical torus containing accelerated condensed matter . The mainstream scientific community has accepted Forward's work. A variant of Burkhard Heim 's theory by Walter Dröscher , Institut für Grenzgebiete der Wissenschaft (IGW), Innsbruck, Austria, and Jocham Häuser, University of Applied Sciences and CLE GmbH, Salzgitter, Germany, predicted

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2436-487: The height of the shielding disk above the earth. Podkletnov and Nieminen described the shape of the weight loss region as a cylinder that extended through the ceiling above the cryostat . A team of scientists at the Australian National University (ANU) led by Professor Andrei Rode created a device similar to a tractor beam to move small particles 1.5 meters through the air. Rather than create

2494-426: The latter case, countermeasures can usually be employed against tractor beams. These may include pressor beams (a stronger pressor beam will counteract a weaker tractor beam) or plane shears a.k.a. shearing planes (a device to "cut" the tractor beam and render it ineffective). In some fictional realities, shields can block tractor beams, or the generators can be disabled by sending a large amount of energy along

2552-434: The liquid helium in an inner, third, vessel. Nowadays few units using multiple cryogens are made with the trend being towards 'cryogen-free' cryostats in which all heat loads are removed by cryocoolers. Cryostats are used in medicine to cut histological slides. They are usually used in a process called frozen section histology (see Frozen section procedure ). The cryostat is essentially an ultrafine "deli-slicer" , called

2610-547: The local cosmological constant . Modanese described several effects regarding responses to modifications to the local cosmological constant within the superconductor. Ning Wu of the Institute of High Energy Physics (Beijing), used the quantum gauge theory of gravity he had developed in 2001 to explain Podkletnov's observations. Wu's theory approximated the relative gravity loss as 0.03% (an order of magnitude smaller than

2668-447: The main stage and 1 K pot. Temperatures below that can be reached using magnetic refrigeration . Cryostats used in MRI machines are designed to hold a cryogen , typically helium , in a liquid state with minimal evaporation (boil-off). The liquid helium bath is designed to keep the superconducting magnet 's bobbin of superconductive wire in its superconductive state. In this state,

2726-428: The microtome can be achieved by hand via a wheel mounted outside the chamber. Newer microtomes have electric push button advancement of the tissue. The precision of the cutting is in micrometres. Tissue are sectioned as thin as 1 micrometre. Usual histology slides are mounted with a thickness of about 7 micrometres. Specimens that are soft at room temperature are mounted on a cutting medium (often made of egg white) on

2784-537: The optical flow, over half a centimeter. In 2019, researchers at the University of Washington used a tractor beam to assemble nanoscale materials in a process they describe as "photonic nanosoldering". Science fiction movies and telecasts normally depict tractor and repulsor beams as audible, narrow rays of visible light covering a small target area. Tractor beams are most commonly used on spaceships and space stations . They are generally used in three ways: In

2842-455: The other. The outer vessel is evacuated with the vacuum acting as a thermal insulator. The inner vessel contains the cryogen and is supported within the outer vessel by structures made from low-conductivity materials. An intermediate shield between the outer and inner vessels intercepts the heat radiated from the outer vessel. This heat is removed by a cryocooler. Older helium cryostats used a liquid nitrogen vessel as this radiation shield and had

2900-534: The propagation direction is small, attractive optical force is possible. The Chinese scientists suggest this possibility may be implemented for optical micromanipulation. In 2013, scientists at the Institute of Scientific Instruments (ISI) and the University of St Andrews created a tractor beam that pulls objects on a microscopic level. The study states that this technique may have potential for bio-medical research. Professor Zemanek said: "The whole team have spent

2958-472: The radiation pressure that ordinarily would drive them down the optical axis. Orbital angular momentum transferred from the solenoid beam's helical wavefronts then drives the trapped objects upstream along the spiral. Both Bessel-beam and solenoidal tractor beams are being considered for applications in space exploration by NASA . In March 2011, Chinese scientists posited that a specific type of Bessel beam (a special kind of laser that does not diffract at

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3016-415: The reported range of 0.3–0.5%). C. S. Unnikrishan, Tata Institute of Fundamental Research , Mumbai, showed that if the effect had been caused by gravitational shielding, the shape of the shielded region would be similar to a shadow from the gravitational shield. For example, the shape of the shielded region above a disk would be conical. The height of the cone's apex above the disk would vary directly with

3074-833: The surface. Owing to this method, such a device cannot work in space due to lack of air. Rode states that there are practical applications for the device on Earth, for example, the transportation of microscopic hazardous materials and other microscopic objects. John Sinko and Clifford Schlecht researched a form of reversed-thrust laser propulsion as a macroscopic laser tractor beam. Intended applications include remotely manipulating space objects at distances up to about 100 km, removal of space debris, and retrieval of adrift astronauts or tools on-orbit. Functioning tractor beams based on solenoidal modes of light were demonstrated in 2010 by physicists at New York University . The spiraling intensity distribution in these non-diffracting beams tends to trap illuminated objects and thus helps to overcome

3132-489: The vessel. A burst disk , usually made of carbon, is placed within the chimney or vent pipe so that during a pressure excursion, the gaseous helium can be safely vented out of the MRI suite. Modern MRI cryostats use a mechanical refrigerator ( cryocooler ) to re-condense the helium gas and return it to the bath, to maintain cryogenic conditions and to conserve helium. Typically cryostats are manufactured with two vessels, one inside

3190-405: The wire has no electrical resistance and very large currents are maintained with low power input. To maintain superconductivity, the bobbin must be kept below its transition temperature by being immersed in the liquid helium. If, for any reason, the wire becomes resistive, i.e. loses superconductivity, a condition known as a " quench ", the liquid helium evaporates, instantly raising pressure within

3248-495: The world tried to replicate Podkletnov's gravity shielding observations. Italian physicist Giovanni Modanese, while a Von Humboldt Fellow at the Max Planck Institute for Physics , made the first attempt to provide a theoretical explanation of Podkletnov's observations. He argued that the shielding effect and slight expulsive force at the border of the shielded zone could be explained in terms of induced changes in

3306-458: Was made available with instructions to build a rudimentary device. In 2016, Rice University scientists discovered that Tesla coils can generate force fields able to manipulate matter through a process called teslaphoresis. In December 2016, researchers were able to manipulate the movement of bacterial cells using a tractor beam, thereby opening the possibility that tractor beams could have future applications in biological sciences. In 2018,

3364-469: Was published in Nature in 2014. In the same year, Dr. Horst Punzmann and his team at ANU developed a tractor beam that works on water, which could potentially be used to contain oil spills, control floating objects, or study the formation of rips on beaches. In 2015, a team of researchers built the world's first sonic tractor beam that can lift and move objects using sound waves. An Instructables webpage

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