title: Interstellar travel

text: As of 2022, five uncrewed spacecraft, all launched and operated by the United States, have achieved the escape velocity required to leave the Solar System as part of missions to explore parts of the outer system. They will therefore continue to travel through interstellar space indefinitely. However, they will not approach another star for hundreds of thousands of years, long after they have ceased to operate (though in theory the Voyager Golden Record would be playable in the highly unlikely event that the spacecraft is retrieved by an extraterrestrial civilization).


title: Interstellar travel

text: The speeds required for interstellar travel in a human lifetime far exceed what current methods of space travel can provide. Even with a hypothetically perfectly efficient propulsion system, the kinetic energy corresponding to those speeds is enormous by today's standards of energy development. Moreover, collisions by spacecraft with cosmic dust and gas at such speeds would be very dangerous for both passengers and the spacecraft itself.


title: Interstellar travel

text: A number of strategies have been proposed to deal with these problems, ranging from giant arks that would carry entire societies and ecosystems, to microscopic space probes. Many different spacecraft propulsion systems have been proposed to give spacecraft the required speeds, including nuclear propulsion, beam-powered propulsion, and methods based on speculative physics.


title: Interstellar travel

text: Humanity would need to overcome considerable technological and economic challenges to achieve either crewed and uncrewed interstellar travel. Even the most optimistic views forecast that it will be decades before this milestone is reached. However, in spite of the challenges, a wide range of scientific benefits are expected should interstellar travel become a reality.


title: Interstellar travel

text: Most interstellar travel concepts require a developed space logistics system capable of moving millions of tonnes to a construction / operating location, and most would require gigawatt-scale power for construction or power (such as Star Wisp or Light Sailtype concepts). Such a system could grow organically if space-based solar power became a significant component of Earth's energy mix. Consumer demand for a multi-terawatt system would create the necessary multi-million ton/year logistical system.


title: Interstellar travel

text: Distances between the planets in the Solar System are often measured in astronomical units (AU), defined as the average distance between the Sun and Earth, some . Venus, the closest planet to Earth is (at closest approach) 0.28 AU away. Neptune, the farthest planet from the Sun, is 29.8 AU away. As of September 20, 2022, Voyager 1, the farthest human-made object from Earth, is 157 AU away.


title: Interstellar travel

text: The closest known star, Proxima Centauri, is approximately away, or over 9,000 times farther away than Neptune.


title: Interstellar travel

text: Because of this, distances between stars are usually expressed in light-years (defined as the distance that light travels in vacuum in one Julian year) or in parsecs (one parsec is 3.26 ly, the distance at which stellar parallax is exactly one arcsecond, hence the name). Light in a vacuum travels around per second, so 1 light-year is about or AU. Hence, Proxima Centauri is approximately 4.243 light-years from Earth.


title: Interstellar travel

text: Another way of understanding the vastness of interstellar distances is by scaling: One of the closest stars to the Sun, Alpha Centauri A (a Sun-like star that is one of two companions of Proxima Centauri), can be pictured by scaling down the Earth–Sun distance to . On this scale, the distance to Alpha Centauri A would be .


title: Interstellar travel

text: The fastest outward-bound spacecraft yet sent, Voyager 1, has covered 1/600 of a light-year in 30 years and is currently moving at 1/18,000 the speed of light. At this rate, a journey to Proxima Centauri would take 80,000 years.


title: Interstellar travel

text: A significant factor contributing to the difficulty is the energy that must be supplied to obtain a reasonable travel time. A lower bound for the required energy is the kinetic energy formula_1 where formula_2 is the final mass. If deceleration on arrival is desired and cannot be achieved by any means other than the engines of the ship, then the lower bound for the required energy is doubled to formula_3.


title: Interstellar travel

text: The velocity for a crewed round trip of a few decades to even the nearest star is several thousand times greater than those of present space vehicles. This means that due to the formula_4 term in the kinetic energy formula, millions of times as much energy is required. Accelerating one ton to one-tenth of the speed of light requires at least (world energy consumption 2008 was 143,851 terawatt-hours), without factoring in efficiency of the propulsion mechanism. This energy has to be generated onboard from stored fuel, harvested from the interstellar medium, or projected over immense distances.


title: Interstellar travel

text: A knowledge of the properties of the interstellar gas and dust through which the vehicle must pass is essential for the design of any interstellar space mission. A major issue with traveling at extremely high speeds is that due to the requisite high relative speeds and large kinetic energies, collisions with interstellar dust could cause considerable damage to the craft. Various shielding methods to mitigate this problem have been proposed. Larger objects (such as macroscopic dust grains) are far less common, but would be much more destructive. The risks of impacting such objects and mitigation methods have been discussed in literature, but many unknowns remain. An additional consideration is that due the non-homogeneous distribution of interstellar matter around the Sun, these risks would vary between different trajectories. Although a high density interstellar medium may cause difficulties for many interstellar travel concepts, interstellar ramjets, and some proposed concepts for decelerating interstellar spacecraft, would actually benefit from a denser interstellar medium.


title: Interstellar travel

text: The crew of an interstellar ship would face several significant hazards, including the psychological effects of long-term isolation, the physiological effects of extreme acceleration, the effects of exposure to ionising radiation, and the physiological effects of weightlessness to the muscles, joints, bones, immune system, and eyes. There also exists the risk of impact by micrometeoroids and other space debris. These risks represent challenges that have yet to be overcome.


title: Interstellar travel

text: The physicist Robert L. Forward has argued that an interstellar mission that cannot be completed within 50 years should not be started at all. Instead, assuming that a civilization is still on an increasing curve of propulsion system velocity and not yet having reached the limit, the resources should be invested in designing a better propulsion system. This is because a slow spacecraft would probably be passed by another mission sent later with more advanced propulsion (the incessant obsolescence postulate).


title: Interstellar travel

text: On the other hand, Andrew Kennedy has shown that if one calculates the journey time to a given destination as the rate of travel speed derived from growth (even exponential growth) increases, there is a clear minimum in the total time to that destination from now. Voyages undertaken before the minimum will be overtaken by those that leave at the minimum, whereas voyages that leave after the minimum will never overtake those that left at the minimum.


title: Interstellar travel

text: There are 59 known stellar systems within 40 light years of the Sun, containing 81 visible stars. The following could be considered prime targets for interstellar missions:


title: Interstellar travel

text: Existing astronomical technology is capable of finding planetary systems around these objects, increasing their potential for exploration.


title: Interstellar travel

text: Slow interstellar missions based on current and near-future propulsion technologies are associated with trip times starting from about one hundred years to thousands of years. These missions consist of sending a robotic probe to a nearby star for exploration, similar to interplanetary probes like those used in the Voyager program. By taking along no crew, the cost and complexity of the mission is significantly reduced although technology lifetime is still a significant issue next to obtaining a reasonable speed of travel. Proposed concepts include Project Daedalus, Project Icarus, Project Dragonfly, Project Longshot, and more recently Breakthrough Starshot.


title: Interstellar travel

text: Near-lightspeed nano spacecraft might be possible within the near future built on existing microchip technology with a newly developed nanoscale thruster. Researchers at the University of Michigan are developing thrusters that use nanoparticles as propellant. Their technology is called "nanoparticle field extraction thruster", or nanoFET. These devices act like small particle accelerators shooting conductive nanoparticles out into space.


title: Interstellar travel

text: Michio Kaku, a theoretical physicist, has suggested that clouds of "smart dust" be sent to the stars, which may become possible with advances in nanotechnology. Kaku also notes that a large number of nanoprobes would need to be sent due to the vulnerability of very small probes to be easily deflected by magnetic fields, micrometeorites and other dangers to ensure the chances that at least one nanoprobe will survive the journey and reach the destination.


title: Interstellar travel

text: As a near-term solution, small, laser-propelled interstellar probes, based on current CubeSat technology were proposed in the context of Project Dragonfly.


title: Interstellar travel

text: In crewed missions, the duration of a slow interstellar journey presents a major obstacle and existing concepts deal with this problem in different ways. They can be distinguished by the "state" in which humans are transported on-board of the spacecraft.


title: Interstellar travel

text: A generation ship (or world ship) is a type of interstellar ark in which the crew that arrives at the destination is descended from those who started the journey. Generation ships are not currently feasible because of the difficulty of constructing a ship of the enormous required scale and the great biological and sociological problems that life aboard such a ship raises.


title: Interstellar travel

text: Scientists and writers have postulated various techniques for suspended animation. These include human hibernation and cryonic preservation. Although neither is currently practical, they offer the possibility of sleeper ships in which the passengers lie inert for the long duration of the voyage.


title: Interstellar travel

text: A robotic interstellar mission carrying some number of frozen early stage human embryos is another theoretical possibility. This method of space colonization requires, among other things, the development of an artificial uterus, the prior detection of a habitable terrestrial planet, and advances in the field of fully autonomous mobile robots and educational robots that would replace human parents.


title: Interstellar travel

text: Interstellar space is not completely empty; it contains trillions of icy bodies ranging from small asteroids (Oort cloud) to possible rogue planets. There may be ways to take advantage of these resources for a good part of an interstellar trip, slowly hopping from body to body or setting up waystations along the way.


title: Interstellar travel

text: If a spaceship could average 10 percent of light speed (and decelerate at the destination, for human crewed missions), this would be enough to reach Proxima Centauri in forty years. Several propulsion concepts have been proposed that might be eventually developed to accomplish this (see § Propulsion below), but none of them are ready for near-term (few decades) developments at acceptable cost.


title: Interstellar travel

text: Relativistic time dilation allows a traveler to experience time more slowly, the closer their speed is to the speed of light. This apparent slowing becomes noticeable when velocities above 80% of the speed of light are attained. Clocks aboard an interstellar ship would run slower than Earth clocks, so if a ship's engines were capable of continuously generating around 1 g of acceleration (which is comfortable for humans), the ship could reach almost anywhere in the galaxy and return to Earth within 40 years ship-time (see diagram). Upon return, there would be a difference between the time elapsed on the astronaut's ship and the time elapsed on Earth.


title: Interstellar travel

text: For example, a spaceship could travel to a star 32 light-years away, initially accelerating at a constant 1.03g (i.e. 10.1 m/s) for 1.32 years (ship time), then stopping its engines and coasting for the next 17.3 years (ship time) at a constant speed, then decelerating again for 1.32 ship-years, and coming to a stop at the destination. After a short visit, the astronaut could return to Earth the same way. After the full round-trip, the clocks on board the ship show that 40 years have passed, but according to those on Earth, the ship comes back 76 years after launch.


title: Interstellar travel

text: From the viewpoint of the astronaut, onboard clocks seem to be running normally. The star ahead seems to be approaching at a speed of 0.87 light years per ship-year. The universe would appear contracted along the direction of travel to half the size it had when the ship was at rest; the distance between that star and the Sun would seem to be 16 light years as measured by the astronaut.


title: Interstellar travel

text: At higher speeds, the time on board will run even slower, so the astronaut could travel to the center of the Milky Way (30,000 light years from Earth) and back in 40 years ship-time. But the speed according to Earth clocks will always be less than 1 light year per Earth year, so, when back home, the astronaut will find that more than 60 thousand years will have passed on Earth.


title: Interstellar travel

text: Regardless of how it is achieved, a propulsion system that could produce acceleration continuously from departure to arrival would be the fastest method of travel. A constant acceleration journey is one where the propulsion system accelerates the ship at a constant rate for the first half of the journey, and then decelerates for the second half, so that it arrives at the destination stationary relative to where it began. If this were performed with an acceleration similar to that experienced at the Earth's surface, it would have the added advantage of producing artificial "gravity" for the crew. Supplying the energy required, however, would be prohibitively expensive with current technology.


title: Interstellar travel

text: From the perspective of a planetary observer, the ship will appear to accelerate steadily at first, but then more gradually as it approaches the speed of light (which it cannot exceed). It will undergo hyperbolic motion. The ship will be close to the speed of light after about a year of accelerating and remain at that speed until it brakes for the end of the journey.


title: Interstellar travel

text: From the perspective of an onboard observer, the crew will feel a gravitational field opposite the engine's acceleration, and the universe ahead will appear to fall in that field, undergoing hyperbolic motion. As part of this, distances between objects in the direction of the ship's motion will gradually contract until the ship begins to decelerate, at which time an onboard observer's experience of the gravitational field will be reversed.


title: Interstellar travel

text: When the ship reaches its destination, if it were to exchange a message with its origin planet, it would find that less time had elapsed on board than had elapsed for the planetary observer, due to time dilation and length contraction.


title: Interstellar travel

text: All rocket concepts are limited by the rocket equation, which sets the characteristic velocity available as a function of exhaust velocity and mass ratio, the ratio of initial ("M", including fuel) to final ("M", fuel depleted) mass.


title: Interstellar travel

text: Very high specific power, the ratio of thrust to total vehicle mass, is required to reach interstellar targets within sub-century time-frames. Some heat transfer is inevitable and a tremendous heating load must be adequately handled.


title: Interstellar travel

text: Thus, for interstellar rocket concepts of all technologies, a key engineering problem (seldom explicitly discussed) is limiting the heat transfer from the exhaust stream back into the vehicle.


title: Interstellar travel

text: A type of electric propulsion, spacecraft such as "Dawn" use an ion engine. In an ion engine, electric power is used to create charged particles of the propellant, usually the gas xenon, and accelerate them to extremely high velocities. The exhaust velocity of conventional rockets is limited to about 5 km/s by the chemical energy stored in the fuel's molecular bonds. They produce a high thrust (about 10 N), but they have a low specific impulse, and that limits their top speed. By contrast, ion engines have low force, but the top speed in principle is limited only by the electrical power available on the spacecraft and on the gas ions being accelerated. The exhaust speed of the charged particles range from 15 km/s to 35 km/s.<ref name="http://www.iflscience.com"></ref>


title: Interstellar travel

text: Nuclear-electric or plasma engines, operating for long periods at low thrust and powered by fission reactors, have the potential to reach speeds much greater than chemically powered vehicles or nuclear-thermal rockets. Such vehicles probably have the potential to power solar system exploration with reasonable trip times within the current century. Because of their low-thrust propulsion, they would be limited to off-planet, deep-space operation. Electrically powered spacecraft propulsion powered by a portable power-source, say a nuclear reactor, producing only small accelerations, would take centuries to reach for example 15% of the velocity of light, thus unsuitable for interstellar flight during a single human lifetime.


title: Interstellar travel

text: Fission-fragment rockets use nuclear fission to create high-speed jets of fission fragments, which are ejected at speeds of up to . With fission, the energy output is approximately 0.1% of the total mass-energy of the reactor fuel and limits the effective exhaust velocity to about 5% of the velocity of light. For maximum velocity, the reaction mass should optimally consist of fission products, the "ash" of the primary energy source, so no extra reaction mass need be bookkept in the mass ratio.


title: Interstellar travel

text: Based on work in the late 1950s to the early 1960s, it has been technically possible to build spaceships with nuclear pulse propulsion engines, i.e. driven by a series of nuclear explosions. This propulsion system contains the prospect of very high specific impulse (space travel's equivalent of fuel economy) and high specific power.


title: Interstellar travel

text: Project Orion team member Freeman Dyson proposed in 1968 an interstellar spacecraft using nuclear pulse propulsion that used pure deuterium fusion detonations with a very high fuel-burnup fraction. He computed an exhaust velocity of 15,000 km/s and a 100,000-tonne space vehicle able to achieve a 20,000 km/s delta-v allowing a flight-time to Alpha Centauri of 130 years. Later studies indicate that the top cruise velocity that can theoretically be achieved by a Teller-Ulam thermonuclear unit powered Orion starship, assuming no fuel is saved for slowing back down, is about 8% to 10% of the speed of light (0.08-0.1c). An atomic (fission) Orion can achieve perhaps 3%-5% of the speed of light. A nuclear pulse drive starship powered by fusion-antimatter catalyzed nuclear pulse propulsion units would be similarly in the 10% range and pure matter-antimatter annihilation rockets would be theoretically capable of obtaining a velocity between 50% to 80% of the speed of light. In each case saving fuel for slowing down halves the maximum speed. The concept of using a magnetic sail to decelerate the spacecraft as it approaches its destination has been discussed as an alternative to using propellant, this would allow the ship to travel near the maximum theoretical velocity. Alternative designs utilizing similar principles include Project Longshot, Project Daedalus, and Mini-Mag Orion. The principle of external nuclear pulse propulsion to maximize survivable power has remained common among serious concepts for interstellar flight without external power beaming and for very high-performance interplanetary flight.


title: Interstellar travel

text: In the 1970s the Nuclear Pulse Propulsion concept further was refined by Project Daedalus by use of externally triggered inertial confinement fusion, in this case producing fusion explosions via compressing fusion fuel pellets with high-powered electron beams. Since then, lasers, ion beams, neutral particle beams and hyper-kinetic projectiles have been suggested to produce nuclear pulses for propulsion purposes.


title: Interstellar travel

text: A current impediment to the development of "any" nuclear-explosion-powered spacecraft is the 1963 Partial Test Ban Treaty, which includes a prohibition on the detonation of any nuclear devices (even non-weapon based) in outer space. This treaty would, therefore, need to be renegotiated, although a project on the scale of an interstellar mission using currently foreseeable technology would probably require international cooperation on at least the scale of the International Space Station.


title: Interstellar travel

text: Another issue to be considered, would be the g-forces imparted to a rapidly accelerated spacecraft, cargo, and passengers inside (see Inertia negation).


title: Interstellar travel

text: Fusion rocket starships, powered by nuclear fusion reactions, should conceivably be able to reach speeds of the order of 10% of that of light, based on energy considerations alone. In theory, a large number of stages could push a vehicle arbitrarily close to the speed of light. These would "burn" such light element fuels as deuterium, tritium, He, B, and Li. Because fusion yields about 0.3–0.9% of the mass of the nuclear fuel as released energy, it is energetically more favorable than fission, which releases <0.1% of the fuel's mass-energy. The maximum exhaust velocities potentially energetically available are correspondingly higher than for fission, typically 4–10% of the speed of light. However, the most easily achievable fusion reactions release a large fraction of their energy as high-energy neutrons, which are a significant source of energy loss. Thus, although these concepts seem to offer the best (nearest-term) prospects for travel to the nearest stars within a (long) human lifetime, they still involve massive technological and engineering difficulties, which may turn out to be intractable for decades or centuries.


title: Interstellar travel

text: Early studies include Project Daedalus, performed by the British Interplanetary Society in 1973–1978, and Project Longshot, a student project sponsored by NASA and the US Naval Academy, completed in 1988. Another fairly detailed vehicle system, "Discovery II", designed and optimized for crewed Solar System exploration, based on the DHe reaction but using hydrogen as reaction mass, has been described by a team from NASA's Glenn Research Center. It achieves characteristic velocities of >300 km/s with an acceleration of ~1.7•10 "g", with a ship initial mass of ~1700 metric tons, and payload fraction above 10%. Although these are still far short of the requirements for interstellar travel on human timescales, the study seems to represent a reasonable benchmark towards what may be approachable within several decades, which is not impossibly beyond the current state-of-the-art. Based on the concept's 2.2% burnup fraction it could achieve a pure fusion product exhaust velocity of ~3,000 km/s.


title: Interstellar travel

text: An antimatter rocket would have a far higher energy density and specific impulse than any other proposed class of rocket. If energy resources and efficient production methods are found to make antimatter in the quantities required and store it safely, it would be theoretically possible to reach speeds of several tens of percent that of light. Whether antimatter propulsion could lead to the higher speeds (>90% that of light) at which relativistic time dilation would become more noticeable, thus making time pass at a slower rate for the travelers as perceived by an outside observer, is doubtful owing to the large quantity of antimatter that would be required.


title: Interstellar travel

text: Speculating that production and storage of antimatter should become feasible, two further issues need to be considered. First, in the annihilation of antimatter, much of the energy is lost as high-energy gamma radiation, and especially also as neutrinos, so that only about 40% of "mc" would actually be available if the antimatter were simply allowed to annihilate into radiations thermally. Even so, the energy available for propulsion would be substantially higher than the ~1% of "mc" yield of nuclear fusion, the next-best rival candidate.


title: Interstellar travel

text: Second, heat transfer from the exhaust to the vehicle seems likely to transfer enormous wasted energy into the ship (e.g. for 0.1"g" ship acceleration, approaching 0.3 trillion watts per ton of ship mass), considering the large fraction of the energy that goes into penetrating gamma rays. Even assuming shielding was provided to protect the payload (and passengers on a crewed vehicle), some of the energy would inevitably heat the vehicle, and may thereby prove a limiting factor if useful accelerations are to be achieved.


title: Interstellar travel

text: More recently, Friedwardt Winterberg proposed that a matter-antimatter GeV gamma ray laser photon rocket is possible by a relativistic proton-antiproton pinch discharge, where the recoil from the laser beam is transmitted by the Mössbauer effect to the spacecraft.


title: Interstellar travel

text: Rockets deriving their power from external sources, such as a laser, could replace their internal energy source with an energy collector, potentially reducing the mass of the ship greatly and allowing much higher travel speeds. Geoffrey A. Landis proposed an interstellar probe propelled by an ion thruster powered by the energy beamed to it from a base station laser. Lenard and Andrews proposed using a base station laser to accelerate nuclear fuel pellets towards a Mini-Mag Orion spacecraft that ignites them for propulsion.


title: Interstellar travel

text: A problem with all traditional rocket propulsion methods is that the spacecraft would need to carry its fuel with it, thus making it very massive, in accordance with the rocket equation. Several concepts attempt to escape from this problem:


title: Interstellar travel

text: A radio frequency (RF) resonant cavity thruster is a device that is claimed to be a spacecraft thruster. In 2016, the Advanced Propulsion Physics Laboratory at NASA reported observing a small apparent thrust from one such test, a result not since replicated. One of the designs is called EMDrive. In December 2002, Satellite Propulsion Research Ltd described a working prototype with an alleged total thrust of about 0.02 newtons powered by an 850 W cavity magnetron. The device could operate for only a few dozen seconds before the magnetron failed, due to overheating. The latest test on the EMDrive concluded that it does not work.


title: Interstellar travel

text: Proposed in 2019 by NASA scientist Dr. David Burns, the helical engine concept would use a particle accelerator to accelerate particles to near the speed of light. Since particles traveling at such speeds acquire more mass, it is believed that this mass change could create acceleration. According to Burns, the spacecraft could theoretically reach 99% the speed of light.


title: Interstellar travel

text: In 1960, Robert W. Bussard proposed the Bussard ramjet, a fusion rocket in which a huge scoop would collect the diffuse hydrogen in interstellar space, "burn" it on the fly using a proton–proton chain reaction, and expel it out of the back. Later calculations with more accurate estimates suggest that the thrust generated would be less than the drag caused by any conceivable scoop design. Yet the idea is attractive because the fuel would be collected "en route" (commensurate with the concept of "energy harvesting"), so the craft could theoretically accelerate to near the speed of light. The limitation is due to the fact that the reaction can only accelerate the propellant to 0.12c. Thus the drag of catching interstellar dust and the thrust of accelerating that same dust to 0.12c would be the same when the speed is 0.12c, preventing further acceleration.


title: Interstellar travel

text: A light sail or magnetic sail powered by a massive laser or particle accelerator in the home star system could potentially reach even greater speeds than rocket- or pulse propulsion methods, because it would not need to carry its own reaction mass and therefore would only need to accelerate the craft's payload. Robert L. Forward proposed a means for decelerating an interstellar craft with a light sail of 100 kilometers in the destination star system without requiring a laser array to be present in that system. In this scheme, a secondary sail of 30 kilometers is deployed to the rear of the spacecraft, while the large primary sail is detached from the craft to keep moving forward on its own. Light is reflected from the large primary sail to the secondary sail, which is used to decelerate the secondary sail and the spacecraft payload. In 2002, Geoffrey A. Landis of NASA's Glen Research center also proposed a laser-powered, propulsion, sail ship that would host a diamond sail (of a few nanometers thick) powered with the use of solar energy. With this proposal, this interstellar ship would, theoretically, be able to reach 10 percent the speed of light. It has also been proposed to use beamed-powered propulsion to accelerate a spacecraft, and electromagnetic propulsion to decelerate it; thus, eliminating the problem that the Bussard ramjet has with the drag produced during acceleration.


title: Interstellar travel

text: A magnetic sail could also decelerate at its destination without depending on carried fuel or a driving beam in the destination system, by interacting with the plasma found in the solar wind of the destination star and the interstellar medium.


title: Interstellar travel

text: The following table lists some example concepts using beamed laser propulsion as proposed by the physicist Robert L. Forward:


title: Interstellar travel

text: Achieving start-stop interstellar trip times of less than a human lifetime require mass-ratios of between 1,000 and 1,000,000, even for the nearer stars. This could be achieved by multi-staged vehicles on a vast scale. Alternatively large linear accelerators could propel fuel to fission propelled space-vehicles, avoiding the limitations of the Rocket equation.


title: Interstellar travel

text: Uploaded human minds or AI could be transmitted with laser or radio signals at the speed of light. This requires a receiver at the destination which would first have to be set up e.g. by humans, probes, self replicating machines (potentially along with AI or uploaded humans), or an alien civilization (which might also be in a different galaxy, perhaps a Kardashev type III civilization).


title: Interstellar travel

text: Scientists and authors have postulated a number of ways by which it might be possible to surpass the speed of light, but even the most serious-minded of these are highly speculative.


title: Interstellar travel

text: It is also debatable whether faster-than-light travel is physically possible, in part because of causality concerns: travel faster than light may, under certain conditions, permit travel backwards in time within the context of special relativity. Proposed mechanisms for faster-than-light travel within the theory of general relativity require the existence of exotic matter and, it is not known if it could be produced in sufficient quantities.


title: Interstellar travel

text: In physics, the Alcubierre drive is based on an argument, within the framework of general relativity and without the introduction of wormholes, that it is possible to modify spacetime in a way that allows a spaceship to travel with an arbitrarily large speed by a local expansion of spacetime behind the spaceship and an opposite contraction in front of it. Nevertheless, this concept would require the spaceship to incorporate a region of exotic matter, or the hypothetical concept of negative mass.


title: Interstellar travel

text: A theoretical idea for enabling interstellar travel is to propel a starship by creating an artificial black hole and using a parabolic reflector to reflect its Hawking radiation. Although beyond current technological capabilities, a black hole starship offers some advantages compared to other possible methods. Getting the black hole to act as a power source and engine also requires a way to convert the Hawking radiation into energy and thrust. One potential method involves placing the hole at the focal point of a parabolic reflector attached to the ship, creating forward thrust. A slightly easier, but less efficient method would involve simply absorbing all the gamma radiation heading towards the fore of the ship to push it onwards, and let the rest shoot out the back.


title: Interstellar travel

text: Wormholes are conjectural distortions in spacetime that theorists postulate could connect two arbitrary points in the universe, across an Einstein–Rosen Bridge. It is not known whether wormholes are possible in practice. Although there are solutions to the Einstein equation of general relativity that allow for wormholes, all of the currently known solutions involve some assumption, for example the existence of negative mass, which may be unphysical. However, Cramer "et al." argue that such wormholes might have been created in the early universe, stabilized by cosmic strings. The general theory of wormholes is discussed by Visser in the book "Lorentzian Wormholes".


title: Interstellar travel

text: The Enzmann starship, as detailed by G. Harry Stine in the October 1973 issue of "Analog", was a design for a future starship, based on the ideas of Robert Duncan-Enzmann. The spacecraft itself as proposed used a 12,000,000 ton ball of frozen deuterium to power 12–24 thermonuclear pulse propulsion units. Twice as long as the Empire State Building is tall and assembled in-orbit, the spacecraft was part of a larger project preceded by interstellar probes and telescopic observation of target star systems.


title: Interstellar travel

text: Project Hyperion, one of the projects of Icarus Interstellar has looked into various feasibility issues of crewed interstellar travel. Its members continue to publish on crewed interstellar travel in collaboration with the Initiative for Interstellar Studies.


title: Interstellar travel

text: NASA has been researching interstellar travel since its formation, translating important foreign language papers and conducting early studies on applying fusion propulsion, in the 1960s, and laser propulsion, in the 1970s, to interstellar travel.


title: Interstellar travel

text: In 1994, NASA and JPL cosponsored a "Workshop on Advanced Quantum/Relativity Theory Propulsion" to "establish and use new frames of reference for thinking about the faster-than-light (FTL) question".


title: Interstellar travel

text: The NASA Breakthrough Propulsion Physics Program (terminated in FY 2003 after a 6-year, $1.2-million study, because "No breakthroughs appear imminent.") identified some breakthroughs that are needed for interstellar travel to be possible.


title: Interstellar travel

text: Geoffrey A. Landis of NASA's Glenn Research Center states that a laser-powered interstellar sail ship could possibly be launched within 50 years, using new methods of space travel. "I think that ultimately we're going to do it, it's just a question of when and who," Landis said in an interview. Rockets are too slow to send humans on interstellar missions. Instead, he envisions interstellar craft with extensive sails, propelled by laser light to about one-tenth the speed of light. It would take such a ship about 43 years to reach Alpha Centauri if it passed through the system without stopping. Slowing down to stop at Alpha Centauri could increase the trip to 100 years, whereas a journey without slowing down raises the issue of making sufficiently accurate and useful observations and measurements during a fly-by.


title: Interstellar travel

text: The 100 Year Starship (100YSS) study was the name of a one-year project to assess the attributes of and lay the groundwork for an organization that can carry forward the 100 Year Starship vision. 100YSS-related symposia were organized between 2011 and 2015.


title: Interstellar travel

text: Harold ("Sonny") White from NASA's Johnson Space Center is a member of Icarus Interstellar, the nonprofit foundation whose mission is to realize interstellar flight before the year 2100. At the 2012 meeting of 100YSS, he reported using a laser to try to warp spacetime by 1 part in 10 million with the aim of helping to make interstellar travel possible.


title: Interstellar travel

text: A few organisations dedicated to interstellar propulsion research and advocacy for the case exist worldwide. These are still in their infancy, but are already backed up by a membership of a wide variety of scientists, students and professionals.


title: Interstellar travel

text: The energy requirements make interstellar travel very difficult. It has been reported that at the 2008 Joint Propulsion Conference, multiple experts opined that it was improbable that humans would ever explore beyond the Solar System. Brice N. Cassenti, an associate professor with the Department of Engineering and Science at Rensselaer Polytechnic Institute, stated that at least 100 times the total energy output of the entire world [in a given year] would be required to send a probe to the nearest star.


title: Interstellar travel

text: Astrophysicist Sten Odenwald stated that the basic problem is that through intensive studies of thousands of detected exoplanets, most of the closest destinations within 50 light years do not yield Earth-like planets in the star's habitable zones. Given the multitrillion-dollar expense of some of the proposed technologies, travelers will have to spend up to 200 years traveling at 20% the speed of light to reach the best known destinations. Moreover, once the travelers arrive at their destination (by any means), they will not be able to travel down to the surface of the target world and set up a colony unless the atmosphere is non-lethal. The prospect of making such a journey, only to spend the rest of the colony's life inside a sealed habitat and venturing outside in a spacesuit, may eliminate many prospective targets from the list.


title: Interstellar travel

text: Moving at a speed close to the speed of light and encountering even a tiny stationary object like a grain of sand will have fatal consequences. For example, a gram of matter moving at 90% of the speed of light contains a kinetic energy corresponding to a small nuclear bomb (around 30kt TNT).


title: Interstellar travel

text: One of the major stumbling blocks is having enough Onboard Spares & Repairs facilities for such a lengthy time journey assuming all other considerations are solved, without access to all the resources available on Earth.


title: Interstellar travel

text: Explorative high-speed missions to Alpha Centauri, as planned for by the Breakthrough Starshot initiative, are projected to be realizable within the 21st century. It is alternatively possible to plan for uncrewed slow-cruising missions taking millennia to arrive. These probes would not be for human benefit in the sense that one can not foresee whether there would be anybody around on Earth interested in then back-transmitted science data. An example would be the Genesis mission, which aims to bring unicellular life, in the spirit of directed panspermia, to habitable but otherwise barren planets. Comparatively slow cruising Genesis probes, with a typical speed of formula_5, corresponding to about formula_6, can be decelerated using a magnetic sail. Uncrewed missions not for human benefit would hence be feasible. For biotic ethics, and their extension to space as panbiotic ethics, it is a human purpose to secure and propagate life and to use space to maximize life.


title: Interstellar travel

text: In February 2017, NASA announced that its Spitzer Space Telescope had revealed seven Earth-size planets in the TRAPPIST-1 system orbiting an ultra-cool dwarf star 40 light-years away from the Solar System. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water. The discovery sets a new record for greatest number of habitable-zone planets found around a single star outside the Solar System. All of these seven planets could have liquid water – the key to life as we know it – under the right atmospheric conditions, but the chances are highest with the three in the habitable zone.


title: European Americans

text: European Americans (also referred to as Euro-Americans) are Americans of European ancestry. This term includes people who are descended from the first European settlers in the United States as well as people who are descended from more recent European arrivals. European Americans have been the largest panethnic group in the United States since about the 17th century.


title: European Americans

text: The Spaniards are thought to be the first Europeans to establish a continuous presence in what is now the contiguous United States, with Martín de Argüelles ( 1566) in St. Augustine, then a part of Spanish Florida, and the Russians were the first Europeans to settle in Alaska, establishing Russian America. The first English child born in the Americas was Virginia Dare, born August 18, 1587. She was born in Roanoke Colony, located in present-day North Carolina, which was the first attempt, made by Queen Elizabeth I, to establish a permanent English settlement in North America.


title: European Americans

text: In the 2016 American Community Survey, German Americans (13%), Irish Americans (12%), English Americans (9%), Italian Americans (6%), and Polish Americans (3%) were the five largest self-reported European ancestry groups in the United States, forming over a third of the total population. However, the number of people with British ancestry is considered to be significantly under-counted, as many people in that demographic tend to identify themselves simply as Americans (20,151,829 or 7.2%). The same applies to Americans of Spanish ancestry, as many people in that demographic tend to identify themselves as Hispanic and Latino Americans (58,846,134 or 16.6%), even though they carry a mean of 65.1% European genetic ancestry, mainly from Spain. In the 2000 census over 56 million or 19.9% of the United States population ignored the ancestry question and are classified as "unspecified" and "not reported".


title: European Americans

text: In 1995, as part of a review of the Office of Management and Budget's Statistical Policy Directive No. 15 (Race and Ethnic Standards for Federal Statistics and Administrative Reporting), a survey was conducted of census recipients to determine their preferred terminology for the racial/ethnic groups defined in the Directive. For the "White" group, "European American" came a distant third, preferred by only 2.35% of panel interviewees, as opposed to "White", which was preferred by 61.66%.


title: European Americans

text: The term is sometimes used interchangeably with Caucasian American, White American, and Anglo American in many places around the United States. However, the terms Caucasian and White are racial terms, not geographic, and include some populations whose origin is outside of Europe; and "Anglo-American" also has another definition, meaning Americans with English ancestry.


title: European Americans

text: The term is used by some to emphasize this demographic's European cultural and geographical as well as ancestral origins, parallelling terms such as African Americans and Asian Americans.


title: European Americans

text: In contexts such as medical research, terms such as "white" and "European" have been criticised for vagueness and blurring important distinctions between different groups that happen to fit within the label. Margo Adair suggests that viewing Americans of European descent as a single group contributes to the "Wonder breading" of the United States, eradicating the cultural heritage of individual European ethnicities.


title: European Americans

text: There are a number of subgroupings of European Americans. While these categories may be approximately defined, often due to the imprecise or cultural regionalization of Europe, the subgroups are nevertheless used widely in cultural or ethnic identification. This is particularly the case in diasporic populations, as with European people in the United States generally. In alphabetical order, some of the subgroups are:


title: European Americans

text: Since 1607, some 57 million immigrants have come to the United States from other lands. Approximately 10 million passed through on their way to some other place or returned to their original homelands, leaving a net gain of some 47 million people.


title: European Americans

text: Before 1881, the vast majority of immigrants, almost 86% of the total, arrived from northwest Europe, principally Great Britain, Ireland, Germany, and Scandinavia, known as "Old Immigration". The years between 1881 and 1893 the pattern shifted, in the sources of US "New Immigration".


title: European Americans

text: Between 1894 and 1914, immigrants from southern, central, and eastern Europe accounted for 69% of the total. Prior to 1960, the overwhelming majority came from Europe or of European descent from Canada. Immigration from Europe as a proportion of new arrivals has been in decline since the mid-20th century, with 75.0% of the total foreign-born population born in Europe compared to 12.1% recorded in the 2010 census.


title: European Americans

text: The figures below show that of the total population of specified birthplace in the United States. A total of 11.1% were born-overseas of the total population.


title: European Americans

text: The numbers below give numbers of European Americans as measured by the US Census in 1980, 1990, and 2000. The numbers are measured according to declarations in census responses. This leads to uncertainty over the real meaning of the figures: For instance, as can be seen, according to these figures, the European American population dropped 40 million in ten years, but in fact, this is a reflection of changing census responses. In particular, it reflects the increased popularity of the "American" option following its inclusion as an example in the 2000 census forms.


title: European Americans

text: Breakdowns of the European American population into sub-components is a difficult and rather arbitrary exercise. Farley (1991) argues that "because of ethnic intermarriage, the numerous generations that separate respondents from their forebears and the apparent unimportance to many whites of European origin, responses appear quite inconsistent".


title: European Americans

text: In particular, a large majority of European Americans have ancestry from a number of different countries and the response to a single "ancestry" gives little indication of the backgrounds of Americans today. When only prompted for a single response, the examples given on the census forms and a pride in identifying the more distinctive parts of one's heritage are important factors; these will likely adversely affect the numbers reporting ancestries from the British Isles. Multiple response ancestry data often greatly increase the numbers reporting for the main ancestry groups, although Farley goes as far to conclude that "no simple question will distinguish those who identify strongly with a specific European group from those who report symbolic or imagined ethnicity." He highlights responses in the Current Population Survey (1973) where for the main "old" ancestry groups (e.g., German, Irish, English, and French), over 40% change their reported ancestry over the six-month period between survey waves (page 422).


title: European Americans

text: The largest self-reported ancestries in 2000, reporting over 5 million members, were in order: German, Irish, English, American, Italian, French, and Polish. They have different distributions within the United States; in general, the northern half of the United States from Pennsylvania westward is dominated by German ancestry, and the southern-half by English and American. Irish may be found throughout the entire country. Italian ancestry is most common in the Northeast, Polish in the Great Lakes Region and the Northeast, and French in New England and Louisiana. US Census Bureau statisticians estimate that approximately 62 percent of European Americans today are either wholly or partly of English, Welsh, Irish, or Scottish ancestry. Approximately 86% of European Americans today are of Northwestern and Central European ancestry, and 14% are of Southern European, Southeastern European, Eastern European, and Euro-Latino descent.


title: European Americans

text: As the largest component of the American population, the overall American culture deeply reflects the European-influenced culture that predates the United States of America as an independent state. Much of American culture shows influences from the diverse nations of the United Kingdom and Ireland, such as the English, Irish, Cornish, Manx, Scotch-Irish, Scottish and Welsh. Colonial ties to Great Britain spread the English language, legal system and other cultural attributes. Scholar David Hackett Fischer asserts in "" that the folkways of four groups of people who moved from distinct regions of the United Kingdom to the United States persisted and provide a substantial cultural basis for much of the modern United States. Fischer explains "the origins and stability of a social system which for two centuries has remained stubbornly democratic in its politics, capitalist in its economy, libertarian in its laws and individualist in its society and pluralistic in its culture."


title: European Americans

text: Much of the European-American cultural lineage can be traced back to Western and Northern Europe, which is institutionalized in the government, traditions, and civic education in the United States.


title: European Americans

text: Since most later European Americans have assimilated into American culture, many Americans of European ancestry now generally express their personal ethnic ties sporadically and symbolically and do not consider their specific ethnic origins to be essential to their identity; however, European American ethnic expression has been revived since the 1960s. Some European Americans such as Italians, Greeks, Poles, Germans, Ukrainians, Irish, and others have maintained high levels of ethnic identity. In the 1960s, the melting pot ideal to some extent gave way to increased interest in cultural pluralism, strengthening affirmations of ethnic identity among various American ethnic groups, European as well as others.


title: European Americans

text: The American legal system also has its roots in French philosophy with the separation of powers and the federal system along with English law in common law. For example, elements of the Magna Carta in it contain provisions on criminal law that were incorporated into the Bill of Rights of the US Constitution.


title: European Americans

text: It as well as other documents had elements influencing and incorporated into the United States Constitution.


title: European Americans

text: Some white Americans have varying amounts of Amerindian and sub-Saharan African ancestry. In a recent study, Gonçalves et al. 2007 reported sub-Saharan and Amerindian mtDna lineages at a frequency of 3.1% (respectively 0.9% and 2.2%) in European Americans, although that frequency may be scattered by region.


title: European Americans

text: DNA analysis on white Americans by geneticist Mark D. Shriver showed an average of 0.7% Sub-Saharan African admixture and 3.2% Native American admixture. The same author, in another study, claimed that about 30% of all White Americans, approximately 66 million people, have a median of 2.3% of Sub-Saharan African admixture. Later, Shriver retracted his statement, saying that actually around 5% of White Americans exhibit some detectable level of African ancestry.


title: European Americans

text: From the 23andMe database, about 5 to at least 13 percent of self-identified white American Southerners have greater than 1 percent African ancestry. Southern states with the highest African American populations tended to have the highest percentages of hidden African ancestry. White Americans (European Americans) on average are: "98.6 percent European, 0.19 percent African and 0.18 percent Native American." Inferred British/Irish ancestry is found in European Americans from all states at mean proportions of


title: Criticism of Muhammad

text: Criticism of Muhammad has existed since the 7th century AD, when Muhammad was decried by his Non-Muslim Arab contemporaries for preaching monotheism, and by the Jewish tribes of Arabia for what they claimed were unwarranted appropriation of Biblical narratives and figures and vituperation of the Jewish faith. For these reasons, medieval Jewish writers commonly referred to him by the derogatory nickname "ha-Meshuggah" (, "the Madman" or "the Possessed").


title: Criticism of Muhammad

text: During the Middle Ages, various Western and Byzantine Christian thinkers considered Muhammad to be a perverted, deplorable man, a false prophet, and even the Antichrist, as he was frequently seen in Christendom as a heretic or possessed by demons. Some of them, like Thomas Aquinas, criticized Muhammad's handling of doctrinal matters and his promises of carnal pleasure in the afterlife.


title: Criticism of Muhammad

text: Modern criticism has concerned Muhammad's sincerity as a prophet, his morality, his marriages, his ownership of slaves and his psychological condition. Muhammad has also been accused of sadism and cruelty in the treatment of his enemies, including in the invasion of the Banu Qurayza tribe in Medina.


title: Criticism of Muhammad

text: The earliest documented Christian knowledge of Muhammad stems from Byzantine sources, written shortly after Muhammad's death in 632. In the "Doctrina Jacobi nuper baptizati", a dialogue between a recent Christian convert and several Jews, one participant writes that his brother "wrote to [him] saying that a deceiving prophet has appeared amidst the Saracens". Another participant in the "Doctrina" replies about Muhammad: "He is deceiving. For do prophets come with sword and chariot?, …[Y]ou will discover nothing true from the said prophet except human bloodshed". Another Greek source for Muhammad is Theophanes the Confessor, a 9th-century writer. The earliest Syriac source is the 7th-century writer John bar Penkaye.


title: Criticism of Muhammad

text: One Christian who came under the early dominion of the Islamic Caliphate was John of Damascus (c. 676–749 AD), who was familiar with Islam and Arabic. The second chapter of his book, "The Fount of Wisdom", titled "Concerning Heresies", presents a series of discussions between Christians and Muslims. John claimed that an Arian monk (whom he did not know was Bahira) influenced Muhammad and the writer viewed the Islamic doctrines as nothing more than a hodgepodge culled from the Bible.


title: Criticism of Muhammad

text: Among the first sources representing Muhammad is the polemical work "Concerning Heresy" (Perì hairéseōn) of John of Damascus, translated from Greek into Latin. In this manuscript, the Syrian priest represents Muhammad as a "false prophet," and an "Antichrist". Some demonstrate that Muhammad was pointed out in this manuscript as "Mamed", but this study was corrected by Ahlam Sbaihat who affirmed that it is the form ΜΩΑΜΕθ (Moameth) which is mentioned in this manuscript. The phoneme h and the gemination of m do not exist in Greek so it has disappeared from John's uses.


title: Criticism of Muhammad

text: From the 9th century onwards, highly negative biographies of Muhammad were written in Latin, such as the one by Álvaro of Córdoba proclaiming him the Antichrist. Since the 7th century, Muhammad and his name have been connected to several stereotypes. Many sources mentioned exaggerated and sometimes wrong stereotypes. These stereotypes are born in the East but adopted by or developed in Western cultures. These references played a principal role in introducing Muhammad and his religion to the West as the false prophet, Saracen prince or deity, the Biblical beast, a schismatic from Christianity and a satanic creature, and the Antichrist.


title: Criticism of Muhammad

text: During the 12th century Peter the Venerable, who saw Muhammad as the precursor to the Anti-Christ and the successor of Arius, ordered the translation of the Qur'an into Latin (Lex Mahumet pseudoprophete) and the collection of information on Muhammad so that Islamic teachings could be refuted by Christian scholars. During the 13th century a series of works by European scholars such as Pedro Pascual, Ricoldo de Monte Croce, and Ramon Llull depicted Muhammad as an Antichrist and argued that Islam was a Christian heresy.


title: Criticism of Muhammad

text: According to Hossein Nasr, the earliest European literature often refers to Muhammad unfavorably. A few learned circles of Middle Ages Europeprimarily Latin-literate scholarshad access to fairly extensive biographical material about Muhammad. They interpreted the biography through a Christian religious filter, one that viewed Muhammad as a person who seduced the Saracens into his submission under religious guise. Popular European literature of the time portrayed Muhammad as though he were worshipped by Muslims, similar to an idol or a heathen god.


title: Criticism of Muhammad

text: In later ages, Muhammad came to be seen as a schismatic: Brunetto Latini's 13th century "Li livres dou tresor" represents him as a former monk and cardinal, and Dante's "Divine Comedy" (Inferno, Canto 28), written in the early 1300s, puts Muhammad and his son-in-law, Ali, in Hell "among the sowers of discord and the schismatics, being lacerated by devils again and again."


title: Criticism of Muhammad

text: The fact that Muhammad was unlettered, that he married a wealthy widow, that in his later life he had several wives, that he ruled over a human community, was involved in several wars, and that he died like an ordinary person in contrast to the Christian belief in the supernatural end of Christ's earthly life were all arguments used to discredit Muhammad. One common allegation laid against Muhammad was that he was an impostor who, in order to satisfy his ambition and his lust, propagated religious teachings that he knew to be false.


title: Criticism of Muhammad

text: Some medieval ecclesiastical writers portrayed Muhammad as possessed by Satan, a "precursor of the Antichrist" or the Antichrist himself. In Dante's The Divine Comedy, Muhammad dwells in the 9th "Bolgia" of the Eighth Circle of Hell and is depicted as disemboweled; the contrapasso represented thereby implicates Muhammad as a schismatic, figuratively rending the body of the Catholic Church and compromising the integrity of the truth of Christianity in the same way Muhammad's body is depicted as literally wounded.


title: Criticism of Muhammad

text: A more positive interpretation appears in the 13th-century "Estoire del Saint Grail", the first book in the vast Arthurian cycle, the Lancelot-Grail. In describing the travels of Joseph of Arimathea, keeper of the Holy Grail, the author says that most residents of the Middle East were pagans until the coming of Muhammad, who is shown as a true prophet sent by God to bring Christianity to the region. This mission however failed when Muhammad's pride caused him to alter God's wishes, thereby deceiving his followers. Nevertheless, Muhammad's religion is portrayed as being greatly superior to paganism.


title: Criticism of Muhammad

text: The "Tultusceptru de libro domni Metobii", an Andalusian manuscript with unknown dating, recounts how Muhammad (called Ozim, from Hashim) was tricked by Satan into adulterating an originally pure divine revelation. The story argues God was concerned about the spiritual fate of the Arabs and wanted to correct their deviation from the faith. He then sends an angel to the monk Osius who orders him to preach to the Arabs.


title: Criticism of Muhammad

text: Osius however is in ill-health and orders a young monk, Ozim, to carry out the angel's orders instead. Ozim sets out to follow his orders, but gets stopped by an evil angel on the way. The ignorant Ozim believes him to be the same angel that spoke to Osius before. The evil angel modifies and corrupts the original message given to Ozim by Osius, and renames Ozim Muhammad. From this followed the erroneous teachings of Islam, according to the "Tultusceptru".


title: Criticism of Muhammad

text: In the Middle Ages, it was common for Jewish writers to describe Muhammad as "ha-Meshuggah" ("The Madman"), a term of contempt frequently used in the Bible for those who believe themselves to be prophets.


title: Criticism of Muhammad

text: Thomas Aquinas was highly critical of Muhammad's character and ethics, claiming that his teachings were largely in conformity to his immoral lifestyle. He wrote in Summa Contra Gentiles:


title: Criticism of Muhammad

text: ""[Muhammad] seduced the people by promises of carnal pleasure to which the concupiscence of the flesh goads us. His teaching also contained precepts that were in conformity with his promises, and he gave free rein to carnal pleasure. In all this, as is not unexpected, he was obeyed by carnal men. As for proofs of the truth of his doctrine, he brought forward only such as could be grasped by the natural ability of anyone with a very modest wisdom... Nor do divine pronouncements on the part of preceding prophets offer him any witness. On the contrary, he perverts almost all the testimonies of the Old and New Testaments by making them into fabrications of his own, as can be seen by anyone who examines his law. It was, therefore, a shrewd decision on his part to forbid his followers to read the Old and New Testaments, lest these books convict him of falsity. It is thus clear that those who place any faith in his words believe foolishly".


title: Criticism of Muhammad

text: "Mahomet" (French: "Le fanatisme, ou Mahomet le Prophète", literally "Fanaticism, or Mahomet the Prophet") is a five-act tragedy written in 1736 by French playwright and philosopher Voltaire. It made its debut performance in Lille on 25 April 1741. The play is a study of religious fanaticism and self-serving manipulation based on an episode in the traditional biography of Muhammad in which he orders the murder of his critics. Voltaire described the play as "written in opposition to the founder of a false and barbarous sect to whom could I with more propriety inscribe a satire on the cruelty and errors of a false prophet".


title: Criticism of Muhammad

text: In a letter to Frederick II of Prussia in 1740 Voltaire ascribes to Muhammad a brutality that "is assuredly nothing any man can excuse" and suggests that his following stems from superstition and lack of Enlightenment. He wanted to portray Muhammad as "Tartuffe with a sword in his hand."


title: Criticism of Muhammad

text: As a result, his book, Fanaticism (Mohammad the Prophet), inspired Goethe, who was attracted to Islam, to write a drama on this theme, though completed only the poem Mahomets-Gesang ("Mahomet's Singing").


title: Criticism of Muhammad

text: Modern critics have criticized Muhammad for preaching beliefs that are incompatible with democracy; Somali-Dutch feminist writer Ayaan Hirsi Ali has called him a "tyrant" and a "pervert".


title: Criticism of Muhammad

text: Neuroscientist and prominent ideological critic Sam Harris contrasts the example of Muhammad with that of Jesus Christ. While he regards Christ as something of a "hippie" figure, Muhammad is an altogether different character and one whose example "as held in Islam is universally not [that of] a pacifist," but rather one of a "conquering warlord who spread the faith by the sword." Harris notes that while sayings such as "render unto Caesar that which is Caesar's" provide Christianity with a "rationale for peace," it is impossible to justify non-violence as central to Islam. Harris says that the example of Muhammad provides an imperative to "convert, subjugate, or kill" and "the core principle of Islam is Jihad." Harris also suggests that Muhammad "may well have been schizophrenic," dismissing Muhammad's claim that the Koran was dictated to him by the archangel Gabriel.


title: Criticism of Muhammad

text: American historian Daniel Pipes sees Muhammad as a politician, stating that "because Muhammad created a new community, the religion that was its raison d'être had to meet the political needs of its adherents."


title: Criticism of Muhammad

text: In 2012 a film titled "Innocence of Muslims" and alternatively "The Real Life of Muhammad" and "Muhammad Movie Trailer" was released by Nakoula Basseley Nakoula. A "Vanity Fair" article described the video as "Exceptionally amateurish, with disjointed dialogue, jumpy editing, and performances that would have looked melodramatic even in a silent movie, the clip is clearly designed to offend Muslims, portraying Mohammed as a bloodthirsty murderer and Lothario and pedophile with omnidirectional sexual appetites." Reacting to the release of the film, violent demonstrations and attacks targeted western institutions through the Muslim world.


title: Criticism of Muhammad

text: In the early 20th century Western scholarly views of Muhammad changed, including critical views. In the 1911 "Catholic Encyclopedia" Gabriel Oussani states that Muhammad was inspired by an "imperfect understanding" of Judaism and Christianity, but that the views of Luther and those who call Muhammad a "wicked impostor", a "dastardly liar" and a "willful deceiver" are an "indiscriminate abuse" and "unsupported by facts." Instead, 19th-century Western scholars such as Aloys Sprenger, Theodor Noldeke, Gustav Weil, William Muir, Sigismund Koelle, and D.S. Margoliouth "give us a more correct and unbiased estimate of Muhammad's life and character, and substantially agree as to his motives, prophetic call, personal qualifications, and sincerity."


title: Criticism of Muhammad

text: Muir, Marcus Dods and others have suggested that Muhammad was at first sincere, but later became deceptive. Koelle finds "the key to the first period of Muhammad's life in Khadija, his first wife," after whose death he became prey to his "evil passions." Samuel Marinus Zwemer, a Christian missionary, criticised the life of Muhammad by the standards of the Old and New Testaments, by the pagan morality of his Arab compatriots, and last, by the new law which he brought. Quoting Johnstone, Zwemer concludes by claiming that his harsh judgment rests on evidence which "comes all from the lips and the pens of his [i.e. Muhammad's] own devoted adherents."


title: Criticism of Muhammad

text: Martin Luther referred to Muhammad as "a devil and first-born child of Satan." Luther's primary target of criticism at the time was the Pope, and Luther's characterization of Muhammad was intended to draw a comparison to show that the Pope was worse.


title: Criticism of Muhammad

text: Many early former Muslims such as Ibn al-Rawandi, Al-Ma'arri, and Abu Isa al-Warraq were famous religious skeptics, polymaths, and philosophers that criticized Islam, the alleged authority and reliability of the Qu'ran, Muhammad's morality, and his claims to be a prophet.


title: Criticism of Muhammad

text: The Quran also mentions critics of Muhammad; for example says the critics complained that Muhammad was passing off what others were telling him as revelations:


title: Criticism of Muhammad

text: The disbelievers say, “This ˹Quran˺ is nothing but a fabrication which he made up with the help of others.” Their claim is totally unjustified and untrue! And they say, “˹These revelations are only˺ ancient fables which he has had written down, and they are rehearsed to him morning and evening.”


title: Criticism of Muhammad

text: In his 1875 work Satyarth Prakash, Dayanand Saraswati, the founder of Arya Samaj, quoted and interpreted several verses of the Koran and described Muhammad as "pugnacious", an "imposter", and one who held out "a bait to men and women, in the name of God, to compass his own selfish needs." Swami Vivekananda wrote in his 1896 book Raja Yoga that though Muhammad was inspired, "he was not a trained "Yogi", nor did he know the reason of what he was doing." Vivekananda wrote that great evil has been done through Muhammad's fanaticism with "whole countries destroyed" and "millions upon millions of people killed."


title: Criticism of Muhammad

text: In the 1920s, three caricatures published by Hindus attacked Muhammad and marriages—the book "Vichitra Jivan" (meaning "Strange Life") by Pandit Kalicharan Sharma in 1923, the pamphlet "Rangila Rasul" (meaning "The Colourful Prophet") by an anonymous author going by the pseudonym of Pandit Chamupati in 1924, and the essay "Sair-i-Dozakh" (meaning "The Trip to Hell") by Devi Sharan Sharma in 1927. In "Vichitra Jivan", Sharma wrote that Muhammad fell victim to many evils, all his marriages were extraordinary and improper, and that he suffered from epilepsy.


title: Criticism of Muhammad

text: Sharma examined in detail the "marvelous powers" of Muhammad, the "products of his body", and every feature of his "marital and sexual relations", and ended the book by saying that such a person could not have been a divine messenger. The "Sair-i-Dozakh" was a take on the Isra and Mi'raj, Muhammad's journey to heaven and hell according to Islamic traditions. Described as a "brutal satire" by Gene Thursby, it described a dream purportedly experienced by the author in which he mounts a mysterious animal and sees various Hindu and Sikh deities and Gurus in the realm of salvation.


title: Criticism of Muhammad

text: Sociologist Rodney Stark argues that "the fundamental problem facing Muslim theologians vis-à-vis the morality of slavery is that "Muhammad bought, sold, captured, and owned slaves", and that his followers saw him as the perfect example to emulate. Stark contrasts Islam with Christianity, writing that Christian theologians wouldn't have been able to "work their way around the biblical acceptance of slavery" if Jesus had owned slaves, as Muhammad did.


title: Criticism of Muhammad

text: Slavery existed in pre-Islamic Arabia, and Muhammad never expressed any intention of abolishing the practice, as he saw it "as part of the natural order of things". He did want to improve the condition of slaves, and exhorted his followers to treat them more humanely, i.e., as human beings as well as property, with kindness and compassion.


title: Criticism of Muhammad

text: His decrees greatly limited those who could be enslaved and under what circumstances (including barring Muslims from enslaving other Muslims), allowed slaves to achieve their freedom and made freeing slaves a virtuous act. He made it legal for his men to marry their slaves and their concubines they captured in war. Muhammad would send his companions like Abu Bakr and Uthman ibn Affan to buy slaves to free. Many early converts to Islam were the poor and former slaves like Bilal ibn Rabah al-Habashi.


title: Criticism of Muhammad

text: Norman Geisler accuses Muhammad of "mercilessness" towards the Jewish tribes of Medina. Geisler also argues that Muhammad "had no aversion to politically expedient assassinations", "was not indisposed to breaking promises when he found it advantageous" and "engaged in retaliation towards those who mocked him." The Orientalist William Muir, in assessing Muhammad's character, described him as cruel and faithless in dealing with his enemies.


title: Criticism of Muhammad

text: Seyyed Hossein Nasr, Professor of Islamic studies at George Washington University, relates Jew's story a little different:


title: Criticism of Muhammad

text: Jean de Sismondi suggests that Muhammad had a specific animosity against Jews, because of the few differences that separated two mostly similar cults. He is among the historians suggesting that he killed many Jews through supplice, whereas he was usually known for his clemency.


title: Criticism of Muhammad

text: Muhammad has been often criticized outside of the Islamic world for his treatment of the Jewish tribes of Medina. An example is the mass killing of the men of the Banu Qurayza, a Jewish tribe of Medina. The tribe was accused of having engaged in treasonous agreements with the enemies besieging Medina in the Battle of the Trench in 627.


title: Criticism of Muhammad

text: Ibn Ishaq writes that Muhammad approved the beheading of some 600–700 in all, with some saying as high as 800–900, who surrendered after a siege that lasted several weeks. (Also see Bukhari ) (Yusuf Ali notes that the Qur'an discusses this battle in verses They were buried in a mass grave in the Medina market place, and the women and children were sold into slavery.


title: Criticism of Muhammad

text: According to Norman Stillman, the incident cannot be judged by present-day moral standards. Citing Deut. 20:13–14 as an example, Stillman states that the slaughter of adult males and the enslavement of women and children—though no doubt causing bitter suffering—was common practice throughout the ancient world. According to Rudi Paret, adverse public opinion was more a point of concern to Muhammad when he had some date palms cut down during a siege, than after this incident. Esposito also argues that in Muhammad's time, traitors were executed and points to similar situations in the Bible. Esposito says that Muhammad's motivation was political rather than racial or theological; he was trying to establish Muslim dominance and rule in Arabia.


title: Criticism of Muhammad

text: Some historians, such as W.N. Arafat and Barakat Ahmad, have disputed the historicity of the incident. Ahmad argues that only the leading members of the tribe were killed. Arafat argued based on accounts by Malik ibn Anas and Ibn Hajar that Ibn Ishaq gathered information from descendants of the Qurayza Jews, who exaggerated the details of the incident. He also maintained that not all adult males were killed but only those who actually fought in the battle, however, William Montgomery Watt described this argument as "not entirely convincing."


title: Criticism of Muhammad

text: According to one account, after the last fort of the Jewish settlement called Khaybar was taken by Muhammad and his men, the chief of the Jews, called Kinana ibn al-Rabi, was asked by Muhammad to reveal the location of some hidden treasure. When he refused, Muhammad ordered a man to torture Kinana, and the man "kindled a fire with flint and steel on his chest until he was nearly dead." Kinana was then beheaded, and Muhammad took his young wife Safiyya as a concubine.


title: Criticism of Muhammad

text: Critics take these events, especially the story of the torture of Kinana, to be another blot on Muhammad's character. Those few Western scholars who discuss the alleged torture of Kinana, like William Muir, have generally not questioned the validity of the story. Muslims generally dispute this incident. Some claim that this was yet another story that Ibn Ishaq heard second-hand from Jewish sources, casting doubt on its authenticity. Others argue that Kinana was killed in battle and never taken captive.


title: Criticism of Muhammad

text: One of the popular historical criticisms of Muhammad in the West has been his polygynous marriages. According to American historian John Esposito, the Semitic cultures in general permitted polygamy (for example, the practice could be found in biblical and postbiblical Judaism); it was particularly a common practice among Arabs, especially among nobles and leaders.


title: Criticism of Muhammad

text: Muslims have often pointed out that Muhammad married Khadija (a widow whose age is estimated to have been 40), when he was 25 years old, and remained monogamous to her for more than 24 years until she died. Norman Geisler frames Muhammad's marriages as a question of moral inconsistency, since Muhammad was unwilling to abide by the revealed limit of four wives that he enjoined on other men. states that the limit of four wives does not apply to Muhammad.


title: Criticism of Muhammad

text: In response Aisha is even reported, in Bukhari and Muslim, to have said, "It seems to me that your Lord hastens to satisfy your desire." Muslims have generally responded that the marriages of Muhammad were not conducted to satisfy worldly desires or lusts, but rather they were done for a higher purpose and due to God's command. Medieval Sufi, Ibn Arabi, sees Muhammad's relationships with his wives as a proof of his superiority amongst men. John Esposito states that polygamy served multiple purposes, including solidifying political alliances among Arab chiefs and marrying widows of companions who died in combat that needed protection.


title: Criticism of Muhammad

text: Contrary to Islamic law, Muhammed is accused of treating his wives unequally. He is accused of clearly favouring Aisha among his living wives, explicitly rated Khadija his best wife overall and had the Quranic dispensation to consort with his wives in an Islamically inequitable manner. These actions created jealousy and dissension among his wives and "illustrate the inability of husbands to give equal consideration to multiple wives."


title: Criticism of Muhammad

text: Beginning in the early twentieth century, Christian polemicists and orientalists would attack what they deem to be Muhammad's deviant sexuality, for having married an underage girl; acute condemnations came from the likes of Harvey Newcomb and David Samuel Margoliouth while others were mild, choosing to explain how the "heat of tropics" made "girls of Arabia" mature at an early age. As colonial governments sought to regulate the age of consent and conflicted with traditional legal systems (Sharia etc.), pointers to Aisha's age at marriage proliferated across the archives in explaining the backwardness of Muslim societies and their reticence to reforms. While most Muslims defended the traditionally accepted age of Aisha with vigor emphasizing on cultural relativism, the political dimensions of the marriage, Aisha's "exceptional qualities" etc., some — Abbas Mahmoud al-Aqqad in Egypt and others — chose to re-calculate the age and fix it at late adolescence as a tool of social reform in their homelands or even, mere pandering to different audiences.


title: Criticism of Muhammad

text: Across the late-twentieth century and early twentieth century, Aisha's age has become a tool of polemicists: accusations of pedophilia have been directed at Muhammad — not as a diagnostic category but as the highest category of evil — to account for the apparently higher prevalence of child marriage in Muslim societies etc.


title: Criticism of Muhammad

text: Western criticism has focused especially on the marriage of Muhammad to his first cousin Zaynab bint Jahsh, the divorced wife of Zayd ibn Harithah, an ex-slave whom Muhammad had adopted as his son. According to Tabari, taken from Al-Waqidi, the story goes that "One day Muhammad went out looking for Zayd. There was a covering of haircloth over the doorway, but the wind had lifted the covering so that the doorway was uncovered. Zaynab was in her chamber, undressed, and admiration for her entered the heart of the Prophet. After that Allah made her unattractive to Zayd and he divorced Zainab."


title: Criticism of Muhammad

text: Karen Armstrong's 2006 biography of Muhammad contextualises this: "A pious woman, [Zaynab] was a skilled leather-worker and gave all the proceeds of her craft to the poor. Muhammad seems to have seen her with new eyes and to have fallen in love quite suddenly when he had called at her house one afternoon to speak to Zayd, who happened to be out. Not expecting any visitors, Zaynab had come to the door in dishabille, more revealingly dressed than usual, and Muhammad had averted his eyes hastily, muttering 'Praise be to Allah, who changes men's hearts!'"


title: Criticism of Muhammad

text: According to William Montgomery Watt, Zaynab herself was working for marriage with Muhammad and was not happy being married to Zayd. Watt also places doubt on the story outlined by Al-Waqidi and states that it should be taken with a "grain of salt." According to Watt, Zaynab was either thirty-five or thirty-eight years old at the time and that the story initially outlined by Al-Waqidi in which he detailed Muhammad's incident with Zaynab during the absence of Zayd may have been tampered with in the course of transmission.


title: Criticism of Muhammad

text: According to Mazheruddin Siddiqi, Zaynab as the cousin of Muhammad was seen by him many times before her marriage to Zayd. Siddiqi states: "He [Muhammad] had seen her many times before but he was never attracted to her physical beauty, else he would have married her, instead of insisting on her that she should marry Zaid."


title: Criticism of Muhammad

text: The English translation of the book, "The Wives of the Messenger of Allah" by Muhammad Swaleh Awadh, states that she was married to Muhammad in Dhul Qa'adah, in the fifth year of Hijra. Since Zaynab was the wife of Muhammad's adopted son, pre-Islamic practices frowned upon such her marriage with the prophet. Arab society would have viewed this union as profoundly wrong; because they considered an adopted son was truly a "son", for a man to marry his adopted son's wife—even if she was divorced—was considered wrong.


title: Criticism of Muhammad

text: The marriage was used by Munafiqs of Medina to discredit Muhammad on two fronts, one of double standards as she was his fifth wife, while everyone else was restricted to four, and marrying his adopted son's wife. This was exactly what Muhammad feared and was initially hesitant in marrying her. The Qur'an, however, confirmed that this marriage was valid. Thus Muhammad, confident of his faith in the Qur'an, proceeded to reject the existing Arabic norms. When Zaynab's waiting period from her divorce was complete, Muhammad married her. In reference to this incident, says:


title: Criticism of Muhammad

text: After this verse was announced, Muhammad proceeded to reject the existing Arabic norms on the prohibition to marry the wives of adopted sons, which was considered extremely wrong and incestuous among Arabs. Thereafter the legal status of adoption was not recognised under Islam. Zayd reverted to being known by his original name of "Zayd ibn Harithah" instead of "Zayd ibn Muhammad".


title: Criticism of Muhammad

text: Orientalists and critics have pointed to this Sura as an example of a self-serving revelation that merely reflects Muhammad's own lust and sexual desires rather than the will of God.


title: Criticism of Muhammad

text: John Mason Neale (1818–1866) accused Muhammad of pandering to his followers, arguing that he constructed Islam out of a mixture of beliefs that provided something for everyone.


title: Criticism of Muhammad

text: Thomas Patrick Hughes (b. 1838) argued that the Hajj represents an expedient compromise between Muhammad's monotheistic principles and Arabian paganism.


title: Criticism of Muhammad

text: Islamic scholar Yasir Qadhi stated that while non-Muslims believe Muhammad "adopted certain things from paganism and then added his own two cents for us", he instead states that Muhammad resurrected the original teachings of the Islamic prophet Ibrahim, citing an Islamic narrative of a man named Amr Ibn Luhay who later introduced paganism in Arabia. Muḥammad ibn ʻAbd Allāh Azraqī mentions the story his book titled "Kitāb akhbār Makkah".""


title: Criticism of Muhammad

text: Muhammad is reported to have had mysterious seizures at the moments of inspiration. According to Philip Schaff (1819–1893), during his revelations Muhammad "sometimes growled like a camel, foamed at his mouth, and streamed with perspiration." Welch, a scholar of Islamic studies, in the Encyclopedia of Islam states that the graphic descriptions of Muhammad's condition at these moments may be regarded as genuine, since they are unlikely to have been invented by later Muslims.


title: Criticism of Muhammad

text: According to Welch, these seizures should have been the most convincing evidence for the superhuman origin of Muhammad's inspirations for people around him. Others adopted alternative explanations for these seizures and claimed that he was possessed, a soothsayer, or a magician. Welch states it remains uncertain whether Muhammad had such experiences before he began to see himself as a prophet and if so how long did he have such experiences.


title: Criticism of Muhammad

text: According to Temkin, the first attribution of "epileptic" seizures to Muhammad comes from the 8th century Byzantine historian Theophanes who wrote that Muhammad's wife "was very much grieved that she, being of noble descent, was tied to such a man, who was not only poor but epileptic as well." In the Middle Ages, the general perception of those who suffered epilepsy was an unclean and incurable wretch who might be possessed by the Devil. The political hostility between Islam and Christianity contributed to the continuation of the accusation of epilepsy throughout the Middle Ages. The Christian minister Archdeacon Humphrey Prideaux gave the following description of Muhammad's visions:


title: Criticism of Muhammad

text: was sent from God of purpose to deliver them unto him. And whereas he was subject to the falling-sickness, whenever the fit was upon him, he pretended it to be a Trance, and that the Angel Gabriel comes from God with some Revelations unto him.


title: Criticism of Muhammad

text: Some modern Western scholars also have a skeptical view of Muhammad's seizures. Frank R. Freemon states Muhammad had "conscious control over the course of the spells and can pretend to be in a religious trance." During the nineteenth century, as Islam was no longer a political or military threat to Western society, and perceptions of epilepsy changed, the theological and moral associations with epilepsy were removed; epilepsy was now viewed as a medical disorder. Nineteenth-century orientalist Margoliouth claimed that Muhammad suffered from epilepsy and even occasionally faked it for effect.


title: Criticism of Muhammad

text: Sprenger attributes Muhammad's revelations to epileptic fits or a "paroxysm of cataleptic insanity." In Schaff's view, Muhammad's "early and frequent epileptic fits" provided "some light on his revelations." The most famous epileptic of the 19th century, Fyodor Dostoyevsky (1821–1881) wrote that epileptic attacks have an inspirational quality; he said they are "a supreme exaltation of emotional subjectivity" in which time stands still. Dostoyevsky claimed that his own attacks were similar to those of Muhammad: "Probably it was of such an instant, that the epileptic Mahomet was speaking when he said that he had visited all the dwelling places of Allah within a shorter time than it took for his pitcher full of water to empty itself."


title: Criticism of Muhammad

text: In an essay that discusses views of Muhammad's psychology, Franz Bul (1903) is said to have observed that "hysterical natures find unusual difficulty and often complete inability to distinguish the false from the true", and to have thought this to be "the safest way to interpret the strange inconsistencies in the life of the Prophet." In the same essay Duncan Black Macdonald (1911) is credited with the opinion that "fruitful investigation of the Prophet's life (should) proceed upon the assumption that he was fundamentally a pathological case."


title: Criticism of Muhammad

text: Modern Western scholars of Islam have rejected the diagnosis of epilepsy. Tor Andrae rejects the idea that the inspired state is pathological attributing it to a scientifically superficial and hasty theory arguing that those who consider Muhammad epileptic should consider all types of semi-conscious and trance-like states, occasional loss of consciousness, and similar conditions as epileptic attacks. Andrae writes that "[i]f epilepsy is to denote only those severe attacks which involve serious consequences for the physical and mental health, then the statement that Mohammad suffered from epilepsy must be emphatically rejected." Caesar Farah suggests that "[t]hese insinuations resulted from the 19th-century infatuation with scientifically superficial theories of medical psychology." Noth, in the "Encyclopedia of Islam", states that such accusations were a typical feature of medieval European Christian polemic.


title: Criticism of Muhammad

text: Maxime Rodinson says that it is most probable that Muhammad's conditions was basically of the same kind as that found in many mystics rather than epilepsy. Fazlur Rahman refutes epileptic fits for the following reasons: Muhammad's condition begins with his career at the age of 40; according to the tradition seizures are "invariably" associated with the revelation and never occur by itself. Lastly, a sophisticated society like the Meccan or Medinese would have identified epilepsy clearly and definitely.


title: Criticism of Muhammad

text: William Montgomery Watt also disagrees with the epilepsy diagnosis, saying that "there are no real grounds for such a view." Elaborating, he says that "epilepsy leads to physical and mental degeneration, and there are no signs of that in Muhammad." He then goes further and states that Muhammad was psychologically sound in general: "he (Muhammad) was clearly in full possession of his faculties to the very end of his life." Watt concludes by stating "It is incredible that a person subject to epilepsy, or hysteria, or even ungovernable fits of emotion, could have been the active leader of military expeditions, or the cool far-seeing guide of a city-state and a growing religious community; but all this we know Muhammad to have been."


title: Criticism of Muhammad

text: According to Seyyed Hossein Nasr, Muhammad's sense of fairness and justice was famous, even before his claim of prophet-hood, as people called him al-Amin, the trusted one.


title: Criticism of Muhammad

text: Frank R. Freemon (1976) thinks that the above reasons given by modern biographers of Muhammad in rejection of epilepsy come from the widespread misconceptions about the various types of epilepsy. In his differential diagnosis, Freemon rejects schizophrenic hallucinations, drug-induced mental changes such as might occur after eating plants containing hallucinogenic materials, transient ischemic attacks, hypoglycemia, labyrinthitis, Ménière's disease, or other inner ear maladies.


title: Criticism of Muhammad

text: At the end, Freemon argues that if one were forced to make a diagnosis psychomotor seizures of temporal lobe epilepsy would be the most tenable one, although our lack of scientific as well as historical knowledge makes unequivocal decision impossible. Freemon cites evidences supporting and opposing this diagnosis. In the end, Freemon points out that a medical diagnosis should not ignore Muhammad's moral message because it is just as likely, perhaps more likely, for God communicate with a person in an abnormal state of mind.


title: Criticism of Muhammad

text: From a Muslim point of view, Freemon says, Muhammed's mental state at the time of revelation was unique and is not therefore amenable to medical or scientific discourse. In reaction to Freemon's article, GM. S. Megahed, a Muslim neurologist criticized the article arguing that there are no scientific explanations for many religious phenomena, and that if Muhammad's message is a result of psychomotor seizures, then on the same basis Moses' and Jesus' message would be the result of psychomotor seizures. In response, Freemon attributed such negative reactions to his article to the general misconceptions about epilepsy as a demeaning condition. Freemon said that he did plan to write an article on the inspirational spells of St. Paul, but the existence of such misconceptions caused him to cancel it.


title: Criticism of Muhammad

text: Muhammad has been criticized for several omissions during his prophethood: he left the Muslim community leaderless and divided following his death by failing to clearly and indisputably declare the individual, selection process or institution that should succeed him, he failed to collect the Quran in a definitive text (later achieved during Uthman's Caliphate), and he failed to collect and codify his prophetic tradition, which work was later undertaken by scholars in the 8th and 9th centuries and became the second most important source of Islam's teachings.


title: Criticism of Muhammad

text: According to both Sunni and Shia Muslims, on his way back from his last pilgrimage to Mecca, Muhammad stopped in a place called Ghadir Khumm, and appointed his cousin Ali as his executor of his last will and his Wali. The word Wali was interpreted differently by Sunni and Shia Muslims. Shia believes Muhammad appointed Ali as his successors at the location. Shia also believe Muhammad's Ahl al-Bayt, are the trusted collectors and transmitters of Muhammad's ahadith and trusted interpreters of Quran.


title: Criticism of Muhammad

text: By stating that Muslims should perpetually be ruled by a member of his own Quraysh tribe after him, Muhammed is accused of creating an Islamic aristocracy, contrary to the religion's ostensibly egalitarian principles. In this reckoning, he introduced a hereditary elite topped by his own family and descendants (the Ahlul Bayt and sayyids), followed by his clan (Banu Hashim) then tribe (Quraysh).


title: Criticism of Muhammad

text: William Muir, like many other 19th-century scholars divides Muhammad's life into two periods—Meccan and Medinan. He asserts that "in the Meccan period of [Muhammad's] life there certainly can be traced no personal ends or unworthy motives," painting him as a man of good faith and a genuine reformer. However, that all changed after the "Hijra", according to Muir. "There [in Medina] temporal power, aggrandisement, and self-gratification mingled rapidly with the grand object of the Prophet's life, and they were sought and attained by just the same instrumentality." From that point on, he accuses Muhammad of manufacturing "messages from heaven" in order to justify a lust for women and reprisals against enemies, among other sins.


title: Criticism of Muhammad

text: Philip Schaff says that "in the earlier part of his life he [Muhammad] was a sincere reformer and enthusiast, but after the establishment of his kingdom a slave of ambition for conquest" and describes him as "a slave of sensual passion." William St. Clair Tisdall also accused Muhammad of inventing revelations to justify his own desires.


title: Criticism of Muhammad

text: D.S. Margoliouth, another 19th-century scholar, sees Muhammad as a charlatan who beguiled his followers with techniques like those used by fraudulent mediums today. He has expressed a view that Muhammad faked his religious sincerity, playing the part of a messenger from God like a man in a play, adjusting his performances to create an illusion of spirituality. Margoliouth is especially critical of the character of Muhammad as revealed in Ibn Ishaq's famous biography, which he holds as especially telling because Muslims cannot dismiss it as the writings of an enemy:


title: Criticism of Muhammad

text: According to William Montgomery Watt and Richard Bell, recent writers have generally dismissed the idea that Muhammad deliberately deceived his followers, arguing that Muhammad "was absolutely sincere and acted in complete good faith". According to Nasr,


title: Criticism of Muhammad

text: Modern secular historians generally decline to address the question of whether the messages Muhammad reported being revealed to him were from "his unconscious, the collective unconscious functioning in him, or from some divine source", but they acknowledge that the material came from "beyond his conscious mind." Watt says that sincerity does not directly imply correctness: In contemporary terms, Muhammad might have mistaken for divine revelation his own unconscious. William Montgomery Watt states:


title: Criticism of Muhammad

text: Rudi Paret agrees, writing that "Muhammad was not a deceiver," and Welch also holds that "the really powerful factor in Muhammad's life and the essential clue to his extraordinary success was his unshakable belief from beginning to end that he had been called by God. A conviction such as this, which, once firmly established, does not admit of the slightest doubt, exercises an incalculable influence on others. The certainty with which he came forward as the executor of God's will gave his words and ordinances an authority that proved finally compelling."


title: Criticism of Muhammad

text: Bernard Lewis, another modern historian, commenting on the common Western Medieval view of Muhammad as a self-seeking impostor, states that


title: Criticism of Muhammad

text: Watt rejects the idea that Muhammad's moral behavior deteriorated after he migrated to Medina. He argues that "it is based on too facile a use of the principle that all power corrupts and absolute power corrupts absolutely". Watt interprets incidents in the Medinan period in such a way that they mark "no failure in Muhammad to live to his ideals and no lapse from his moral principles."