Light

Light is electromagnetic radiation with a wavelength that is visible to the eye, or in a more general sense, any electromagnetic radiation in the range from infrared to ultraviolet. The three basic dimensions of light (and of all electromagnetic radiation) are: * intensity (or brilliance or amplitude, perceived by humans as the brightness of the light), * frequency (or wavelength, perceived by humans as the color of the light), and * polarization (or angle of vibration and not perceivable by humans under ordinary circumstances) Due to wave-particle duality, light simultaneously exhibits properties of both waves and Particle physics. The precise nature of light is one of the key questions of modern physics. == Visible electromagnetic radiation== Light is the visible portion of the electromagnetic spectrum, between the frequency of 380 Hertz#SI_Multiples (3.8×10¹⁴ hertz) and 750 Hertz#SI_Multiples (7.5×10¹⁴ hertz). Since the speed (

v

), frequency (

f

\nu

), and wavelength (

\lambda

) of a wave obey the relation: :

v = f~\lambda \,\!

Because the speed of light in a vacuum is fixed, visible light can also be characterised by its wavelength of between 400 nanometres (abbreviated 'nm') and 800 nm (in a vacuum). Light excites the rod cells and cone cells in the retina of the human eye, creating electrical nerve impulses that travel up the optic nerve to the brain, producing vision. ==Speed of light== Although some people speak of the "velocity of light", the word ''velocity'' should be reserved for vector quantities, that is, those with both magnitude and direction. The speed of light is a scalar quantity, having only magnitude and no direction, and therefore ''speed'' is the correct term. The speed of light has been measured many times, by many physicists. The best early measurement is Ole R�mer's (a Danish physicist), in 1676. By observing the motions of Jupiter (planet) and one of its natural satellites, Io (moon), with a telescope, and noting discrepancies in the apparent period of Io's orbit, R�mer calculated a speed of 227,000 kilometres per second (approximately 141,050 miles per second). The first successful measurement of the speed of light using an earthbound apparatus was carried out by Hippolyte Fizeau in 1849. Fizeau directed a beam of light at a mirror several thousand metres away, and placed a rotating cog wheel in the path of the beam from the source to the mirror and back again. At a certain rate of rotation, the beam could pass through one gap in the wheel on the way out and the next gap on the way back. Knowing the distance to the mirror, the number of teeth on the wheel, and the rate of rotation, Fizeau measured the speed of light as 313,000 kilometres per second. Albert A. Michelson improved on R�mer's work in 1926 used rotating mirrors to measure the time it took light to make a round trip from Mt. Wilson to Mt. San Antonio in California. The precise measurements yielded a speed of 186,285 miles/second (299,796 kilometres/second). In daily use, the figures are rounded off to 300,000 km/s and 186,000 miles/s. ==Refraction== All light propagates at a finite speed. Even moving observers always measure the same value of ''c'', the speed of light in vacuum, as ''c'' = 299,792,458 metres per second (186,282.397 miles per second). When light passes through a transparent substance, such as air, water or glass, its speed is reduced, and it undergoes refraction. The reduction of the speed of light in a denser material can be indicated by the refractive index, ''n'', which is defined as: :

n = \frac{c}{v} \;\!

Thus, ''n''=1 in a vacuum and ''n''>1 in matter. When a beam of light enters a medium from vacuum or another medium, it keeps the same frequency and changes its wavelength. If the incident beam is not orthogonal to the edge between the media, the direction of the beam will change. Refraction of light by lens (optics)es is used to focus light in magnifying glasses, spectacles and contact lenses, microscopes and refracting telescopes. ==Optics== The study of light and the interaction of light and matter is termed optics. The observation and study of optical phenomenon such as rainbows offers many clues as to the nature of light as well as much enjoyment. ==Color and wavelengths== The different wavelengths are detected by the human eye and then interpreted by the human brain as colors, ranging from red at the longest wavelengths (lowest frequencies) to violet (color) at the shortest wavelengths (highest frequencies). The intervening frequencies are seen as Orange (colour), yellow, green, blue, and, conventionally, indigo.

The wavelengths of the electromagnetic spectrum immediately outside the range that the human eye is able to perceive are called ''ultraviolet'' (UV) at the short wavelength (high frequency) end and ''infrared'' (IR) at the long wavelength (low frequency) end. Although humans cannot see IR, they do perceive the near infrared (shorter wavelength, higher frequency, higher energy) as heat through receptors in the skin. Cameras that can detect IR and convert it to light are called, depending on their application, night-vision cameras or infrared cameras (not to be confused with an image intensifier that only amplifies available visible light). UV radiation is not directly perceived by humans at all except in a very delayed fashion, as overexposure of the skin to UV light can cause sunburn, or skin cancer, and underexposure can cause Seasonal affective disorder due to vitamin D deficiency. However, because UV is a higher frequency radation than visible light, it very easily can cause materials to fluorescence visible light. Some animals, such as bees, can see UV radiation while others, such as pit viper snakes, can see IR using pits in their heads. == Measurement of light == The following quantities and units are used to measure light. *brightness (or temperature) *illuminance or illumination (SI unit: lux) *luminous flux (SI unit: lumen (unit)) *luminous intensity (SI unit: candela) Light can also be characterised by: *brilliance (or amplitude), *color (or frequency), and *polarization (or angle of vibration). ===SI light units=== == Light sources == There are many sources of light. A body at a given temperature will emit a characteristic spectrum of black body radiation. Examples include sunlight (the radiation emitted by the chromosphere of the Sun at around 6,000 kelvin peaks in the visible region of the electromagnetic spectrum), incandescent light bulbs (which are generally very inefficient, emitting only around 10% of their energy as light and the remainder as "heat", i.e. infrared) and glowing solid particles in flames (see fire, red hot, white hot). Atoms emit and absorb light at characteristic energies. Emission lines can either be stimulated emission, such as visible lasers and microwave maser emission, light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc), and flames (light from the hot gas itself - so, for example, sodium in a gas flame emits characteristic yellow light) or spontaneous emission. Acceleration of a free charged particle, such as an electron, can produce visible radiation: Cyclotron radiation, Synchrotron radiation, and Bremsstrahlung radiation. Particles moving through a medium faster than the speed of light in that medium can produce visible Cherenkov radiation. Certain chemicals produce visible radiation by chemoluminescence. For example, firefly produce chemicals that produce light by these mechanisms, and boats moving through water can disturb phosphorescent plankton. Certain substances produce light when they are illuminated by more energetic radiation, a process known as fluorescence. This is used in strip lights. Particles striking certain chemicals can produce light by phosphorescence, for example, cathodoluminescence. This mechanism is used in oscilloscopes and televisions, and cathode ray tube. Certain other mechanisms can produce light: *scintillation **scintillator *electroluminescence *bioluminescence *sonoluminescence *triboluminescence *radioactivity *particle-antiparticle annihilation == Theories about light == === Early Greek ideas === In 55 BC Lucretius, continuing the ideas of earlier atomism, wrote that light and heat from the Sun were composed of minute particles. Ptolemy also wrote about the refraction of light. === 10th century optical theory === The scientist Abu Ali al-Hasan ibn al-Haytham (965-c.1040), also known as Alhazen, developed a broad theory that explained vision, using geometry and anatomy, which stated that each point on an illuminated area or object radiates light rays in every direction, but that only one ray from each point, which strikes the eye perpendicularly, can be seen. The other rays strike at different angles and are not seen. He used the example of the pinhole camera, which produces an inverted image, to support his argument. Alhazen held light rays to be streams of minute particles that travelled at a finite speed. He improved Ptolemy's theory of the refraction of light. Alhazen's work did not become known in Europe until the late 16th century. === The 'plenum' === Ren� Descartes (1596-1650) held that light was a disturbance of the ''plenum'', the continuous substance of which the universe was composed. In 1637 he published a theory of the refraction of light which wrongly assumed that light travelled faster in a denser medium, by analogy with the behaviour of sound waves. Descartes' theory is often regarded as the forerunner of the wave theory of light. === Particle theory === Pierre Gassendi (1592-1655), an atomist, proposed a particle theory of light which was published posthumously in the 1660s. Isaac Newton studied Gassendi's work at an early age, and preferred his view to Descartes' theory of the ''plenum''. He stated in his ''Hypothesis of Light'' of 1675 that light was composed of corpuscles (particles of matter) which were emitted in all directions from a source. One of Newton's arguments against the wave nature of light was that waves were known to bend around obstacles, while light travelled only in straight lines. He did, however, explain the phenomenon of the diffraction of light (which had been observed by Francesco Grimaldi) by allowing that a light particle could create a localised wave in the aether. Newton's theory could be used to predict the reflection of light, but could only explain refraction by incorrectly assuming that light accelerated upon entering a denser medium because the gravity pull was greater. Newton published the final version of his theory in his ''Opticks'' of 1704. His reputation helped the particle theory of light to dominate physics during the 18th century. === Wave theory === In the 1660s, Robert Hooke published a wave theory of light. Christian Huygens worked out his own wave theory of light in 1678, and published it in his ''Treatise on light'' in 1690. He proposed that light was emitted in all directions as a series of waves in a medium called the ''aether''. As waves are not affected by gravity, it was assumed that they slowed down upon entering a denser medium. The wave theory predicted that light waves could interfere with each other like sound waves (as noted in the 18th century by Thomas Young (scientist)), and that light could be polarization. Young showed by means of a double-slit experiment that light behaved as waves. He also proposed that different colours were caused by different wavelengths of light, and explained colour vision in terms of three-coloured receptors in the eye. Another supporter of the wave theory was Leonhard Euler. He argued in ''Nova theoria lucis et colorum'' (1746) that diffraction could more easily be explained by a wave theory. Later, Augustin Jean Fresnel independently worked out his own wave theory of light, and presented it to the Acad�mie des Sciences in 1817. Simeon Poisson added to Fresnel's mathematical work to produce a convincing argument in favour of the wave theory, helping to overturn Newton's corpuscular theory. The weakness of the wave theory was that light waves, like sound waves, would need a medium for transmission. A hypothetical substance called the luminiferous aether was proposed, but its existence was cast into strong doubt by the Michelson-Morley experiment. Newton's corpuscular theory implied that light would travel faster in a denser medium, while the wave theory of Huygens and others implied the opposite. At that time, the speed of light could not be measured accurately enough to decide which theory was correct. The first to make a sufficiently accurate measurement was L�on Foucault, in 1850. His result supported the wave theory, and the classical particle theory was finally abandoned. === Electromagnetic theory === In 1845, Faraday discovered that the angle of polarisation of a beam of light as it passed through a polarising material could be altered by a magnetic field, an effect now known as Faraday rotation. This was the first evidence that light was related to electromagnetism. Faraday proposed in 1847 that light was a high-frequency electromagnetic vibration, which could propagate even in the absence of a medium such as the aether. Faraday's work inspired James Clerk Maxwell to study electromagnetic radiation and light. Maxwell discovered that self-propagating electromagnetic waves would travel through space at a constant speed, which happened to be equal to the previously measured speed of light. From this, Maxwell concluded that light was a form of electromagnetic radiation: he first stated this result in 1862 in ''On Physical Lines of Force''. In 1873, he published ''A Treatise on Electricity and Magnetism'', which contained a full mathematical description of the behaviour of electric and magnetic fields, still known as Maxwell's equations. The technology of radio transmission was, and still is, based on this theory. The constant speed of light predicted by Maxwell's equations contradicted the mechanical laws of motion that had been unchallenged since the time of Galileo Galilei, which stated that all speeds were relative to the speed of the observer. A solution to this contradiction would later be found by Albert Einstein. === Particle theory revisited === The wave theory was accepted until the late 19th century, when Einstein described the photoelectric effect, by which light striking a surface caused electrons to change their momentum, which indicated a particle-like nature of light. This clearly contradicted the wave theory, and for years physicists tried to rectify this contradiction without success. === Quantum theory === In 1900, Max Planck described quantum theory, in which light is considered to be as a particle that could exist in discrete amounts of energy only. These packets were called quantum, and the particle of light was given the name photon, to correspond with other particles being described around this time, such as the electron and proton. A photon has an energy, E, proportional to its frequency, f, by :

E_f = hf = \frac{hc}{\lambda} \,\!

where h is planck's constant,

\lambda

is the wavelength and c is the speed of light. As it originally stood, this theory did not explain the simultaneous wave-like nature of light, though Planck would later work on theories that did. The Nobel Prize awarded Planck the Nobel Prize for Physics in 1918 for his part in the founding of quantum theory. === Wave-particle duality === The modern theory that explains the nature of light is wave-particle duality, described by Albert Einstein in the early 1900s, based on his work on the photoelectric effect and Planck's results. Einstein determined that the energy of a photon is proportional to its frequency. More generally, the theory states that everything has both a particle nature, and a wave nature, and various experiments can be done to bring out one or the other. The particle nature is more easily discerned if an object has a large mass, so it took until an experiment by Louis de Broglie in 1924 to realise that electrons also exhibited wave-particle duality. Einstein received the Nobel Prize in 1921 for his work with the wave-particle duality on photons, and de Broglie followed in 1929 for his extension to other particles. ===A light wave=== [[Image:light-wave.png|thumb|This is a light wave frozen in time and shows the two components of light; an electric field and a magnetic field that oscillate perpendicular to each other and to the direction of motion (a transverse wave).]] The electric and magnetic fields are perpendicular to the direction of travel and to each other. This picture depicts a very special case, linearly polarized light. See Polarization for a description of the general case and an explanation of linear polarization. While the above statements about the relations of the electric and magnetic fields are always true, the subtle difference in the general case is that the direction and amplitude of the magnetic (or electric) field can vary, in one place, with time, or, in one instant, can vary along the direction of propagation. ==See also== *Color temperature *Huygens' principle *International Commission on Illumination *Light pollution *Lighting *Photic sneeze reflex *Photometry (optics) *Spectrometry Electromagnetism Optics Image processing bn:আলো lv:Gaisma li:Leech jbo:Gusni ms:Cahaya simple:Light ta:ஒளி th:แสง vi:�nh s�ng

Light

I saw a show on PBS where a scientist transmitted music faster than c. He recorded it and played it back on a tape recorder. It was staticy, but recognizable. --Alan D -------------------------------------------------------- See plea for help in article.... :As far as I understand it, the evanescent wave coupling stuff is the same as the other group velocity > ''c'' stuff in the case of extreme absorption. :There seems to be a lot of interest and half-explainations of this topic scattered around the wikipedia, I may try to write a :superluminal communication article, In My Copious Free Time. :What's really interesting is the effect that occurs between the plates of a Casimir Force experiment, that's the only legitimate ''v''>''c'' stuff I know about. -- DrBob ---- How is "velocity" incorrect? It was good enough for Einstein: :In short, let us assume that the simple law of the constancy of the velocity of light c (in vacuum) is justifiably believed by the child at school. [http://www.bartleby.com/173/7.html] I suppose we should make it clear that we are referring to the velocity of the propagation of light. --TheCunctator :Well, if the velocity of light was a constant, then it would always move in the same direction. (Velocity being a vector quantity.) This is not true for all observers (the direction of light propogation being different in different reference frames, e.g. the light-clock thought experiments), and not even true for a single observer (light being able to go in any direction). However, the speed of light, being the magnitute of the velocity, is the same for all observers. :Maybe I'm being nit-picky but it seems that Einstein was being loose with the terminology in the article you reference. I still think 'speed' is the most technically correct. -- DrBob I agree, velocity is generally taken to be a vector quantity and speed is a scalar. The speed of light in vacuum is constanct and equal to ''c''; the velocity vector of light in vacuum is not constant, because light can travel in different directions; the magnitude of the velocity vector is ''c''. --AxelBoldt :Fine with me. I think it would be fair to note that Einstein used "velocity", and define speed. --TheCunctator ----- Are light-years really the prefered unit in Astronomy? I have heard that they are mostly used in popular science articles, but real astronomers use Parsecs instead. I'm not a real astronomer, so i can't vouch for this. -- Geronimo Jones. The star and galaxy catalogs tend to use parsecs rather than light-years, so I'd guess it's a safe bet. ------------ "Light passes through liquids such as water or solids such as glass at reduced volocity." Good point, but I have three reservations: 1 - It's "velocity", not "volocity" 2 - I think it should be "speed", not velocity. Velocity is a vector, right? (Somebody help me out here :-) ) 3 - Maybe this could go in the paragraph here about the speed of light, or in the entry on speed of light linked there - Thanks :-) ----- All good points, I had a lot of trouble that day getting on to Wikipedia. If I can keep getting in I'll try to do something better. My question is why you took all this time on talk and didn't just do a better job including the material. ---- In the section on speed of light, the symbol v - for velocity? :) - renders in my browser as a greek letter nu, which could cause confusion as that is commonly used to represent frequency. This happens throughout except in the last equation, v=c/n , where it is rendered correctly as v, but the whole equation is in larger type. I couldn't find anything to explain this in the markup, except that the last equation had spaces around the "=" whereas the first two did not. Irrelevant as this seemed, I put spaces in the first two and, in preview, the problem was fixed - v rendered as v, and all equations similar (large) font. However, when I saved the changes, it reverted to the earlier rendering, apart from the added spaces. Anyone have an idea what's going on and how to fix it? Do others see the same problem or does it display normally for you? (I'm using Opera 7.23, Windows). I've also had a look in Internet Explorer and seen similar, except a slight difference in font appearance makes me wonder whether I'm seeing, not a Greek "nu" but a cursive "v". Either way, it is confusing. --User:Al-khowarizmi 16:16, 13 Mar 2004 (UTC) :I think it is not a nu but a v in italics; that is what TeX rendered as PNG gives, as opposed to TeX rendered as HTML. For more uniformity specify ''HTML if possible'' in the preferences. --User:Patrick 20:56, 13 Mar 2004 (UTC) Thanx - that fixes it. - Richard The discussion of infra-red (IR) and infra-red cameras is incomplete. Near infra-red is just outside the range of humans vision (730nm - 1100nm), and most infra-red (night-vision) cameras detect these wavelengths. Actually all CCD - CMOS cameras will detect these wavelengths, though normally a filter is put on top of the image sensor to stop wavelengths greater than 700nm from reaching the cameras sensor. Infra-red (forget the exact wavelength, believe between 2000nm - 5000nm?) is detected as heat. It requires a completely different kind of camera / sensor to detect these wavelengths, and these cameras are quite expensive. ---- == Explanation on using Jupiter's moons to calculate speed of light confuses me == I was confused by this explanation: :when Earth and Jupiter were not as close, the moon's revolution seemed to be more. It was clear that light took longer to reach Earth when it was farther away from Jupiter. The speed of light was calculated by analyzing the distance between the two planets at various times. Why would the moon's revolution seem to be more? Let's take a revolution when Jupitar is near Earth starting at n1 and ending at n2. Then, consider a revolution and when Jupiter is far from Earth starting at f1 and ending at f2. Ok, so it takes at extra delay d for the light of the start of the revolution to reach Earth when f1 so, in fact, the revolution started at time f1-d. But so what? The revolution ends at nearly time f2-d also. Thus: :(f2-d) - (f1-d) = f2 - f1 = period of revolution = n2 - n1 Distance from Earth has ''no'' bearing. After thinking for a moment, I have a guess at what the explation was trying to say. When Jupiter and Earth are moving apart, the revolutions of the moon ''would'' seem to take more time. Similarly, the revolutions would seem to speed up as Jupiter and Earth become closer. That is, a distant Jupiter moving closer would seem to have faster moons whereas a nearby Jupiter moving away would seem to have slower revolutions. That is, ''relative motion'' and not ''distance'' is what changes the apparent period of the moon's revolution. If I am correct, then a better explanation would be: :when Earth and Jupiter were moving apart from each other, the moon's revolution seemed to take longer. It was clear that light took longer to reach Earth because Earth and Jupiter had moved apart during the start and the end of the moon's revolution. Similarly, as Earth and Jupiter came closer together, the moon's revolution seemed to take less time. The speed of light was calculated by analyzing the distance between the two planets at various times. However, maybe I'm being a bit too wordy. How about: :when Earth and Jupiter were moving apart from each other, the moon's revolution seemed to take longer. It was clear that light took longer to reach Earth as Earth and Jupiter moved apart. Similarly, as Earth and Jupiter came closer together, the moon's revolution seemed to take less time. The speed of light was calculated by analyzing the distance between the two planets at various times. So, would some astronomer confirm/reject my suggestion? User:WpZurp 02:00, 8 Sep 2004 (UTC) Anyway, I've put in what I believe to be a correction. Makes sense to me. Hope it's right and hope you all like it. User:WpZurp 20:13, 19 Sep 2004 (UTC) ==Restructure== I've restructured the article somewhat, to move the Theories of light down to the bottom, as the ''todo'' and WP:FAC comments suggest, plus other general tidying, also deleting one of the prism images. Some parts are clearly in need of more work. -- User:ALoan User_talk:ALoan 14:43, 11 Nov 2004 (UTC) Should we place the headlines in the article from the Todo-list above? That way it would be easier to edit the article into new subsections. User:Thechamelon 12:52, Apr 19, 2005 (UTC) == lightyear as an unit of measure == light-year is a deprecated but accepted unit. The only unit that should be used in SI should be the meter. The unit parsec is strongly preferred to light-year. Since light-year unit is, to some degree, common used, it worth to explain what it is. == Quantum Electrodynamics == I think a brief explanation of this theory--or at least a link to the related Wikipedia entry--would be appropriate, given that it has resolved the wave-particle duality of light, which this article incorrectly describes as the modern theory of light. == Visible Light No such thing == I was taught in imaging science to never use these 2 words together ; Visible Light It is redundant. If it is Light then it is by definition "Visible" If it is visible then there is some light going on in the equation. Visible portion or region of the electromagnetic spectrum is ok. Or just Light. Light Source, etc. I know it seems short and lonely, but it is correct. :I think it is too common to use "light" when referring to any type of EM radiation used for the purpose of illumination, not just directly visibly. For example, we say "infrared light" often, "infrared radiation" is kind of cumbersome when referring to the frequencies near to visible. If an invisible source of IR radiation is used in conjunction with night vision goggles, it becomes a light source for the camera. Some insects can see "UV light". "UV Radiation" is used when describing ionizing UV that causes cancer, sun tans, and sterilizing of bacteria. "UV Light" is used when referring to near-visible illumination (as in fluorescence, or when describing the visible spectrum of some insects). If you want to argue semantics into the ground then "Visible Light" is incorrect. But if you want to get by outside a physics class, just accept that the phrase "Visible Light" == "Light visible to native human eyes", and that other forms of light exist. User:64.162.10.163 21:52, 28 Mar 2005 (UTC) -------------------------------------------------------------- == Does fluorescence go here? == Hey, in the section about ways to quantify light or measure light: plese don't forget the Spectral power distribution. It is a graph/plot generated by a spectroradiometer reading the Watt/Flux...something at 31 regions along the spectrum from 400 to 700nm.--done I can help. I need the definition bad.--[[User:Dkroll2|Dkroll2]] 22:13, Dec 14, 2004 (UTC) ==Scientific notation or Engineering notation?== The article currently contains the following statement: :''Light is the visible portion of the electromagnetic spectrum, between the frequencies of 3.8�10¹⁴ hertz (abbreviated 'Hz') and 7.5�10¹⁴ Hz. Since the speed (v), frequency (f or ?), and wavelength (?) of a wave obey the relation...'' I don't know about you, but I always find I have a much faster "intuitive" grasp of a quantity if it's stated in "Engineering Notation" (such as "380 THz" or maybe "380�10¹² Hz") rather than pure Scientific Notation ("3.8�10¹⁴ Hz"). I think it's because I routinely work with kilo, mega, giga, tera, and with nanometers and the rest of the SI units and prefixes but not with pure scientific notation. Does anyone else agree with this? And do you agree with it to the extent that we change the article to use this form? User:Atlant 12:57, 23 Apr 2005 (UTC) *I don't ''think'' there can be any objections to using SI-standard abbreviations. Not so sure about Engineering notation in the sense of using the raw unit but constraining the exponent of ten to be a multiple of a 3. It's offered e.g. on HP calculators, but is it really ''used'' in engineering publications? User:Dpbsmith User_talk:dpbsmith 15:11, 23 Apr 2005 (UTC) :I've only seen use of prefixes. - User:Omegatron 17:37, Apr 23, 2005 (UTC) I guess I'm arguing in favor of using the SI prefixes rather than ANY scientific or engineering notation. User:Atlant 00:36, 24 Apr 2005 (UTC) :How about: "Light is the visible portion of the electromagnetic spectrum, between the frequency of 380 Hertz#SI_Multiples (3.8×10¹⁴ hertz) and 750 Hertz#SI_Multiples (7.5×10¹⁴ hertz)." The THz link goes to the SI multiples of Hertz, so one could even omit the info in parenthesis. User:Splarka 01:09, 24 Apr 2005 (UTC) ::Ah. Cutting the Gordian knot, eh? Using both works for me. User:Dpbsmith User_talk:dpbsmith 11:30, 24 Apr 2005 (UTC) That's great -- let's do that. User:Atlant 12:52, 24 Apr 2005 (UTC) :Snip Snip. (Since we all seem to be in agreement) User:Splarka 19:28, 24 Apr 2005 (UTC)

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