How does light exist?
122567
Light of a form of energy. Energy is the only thing in universe. There are different forms for energy. Light is just another form of energy - A radiation. \n\n   Hope you know that matter (whatever it is) is just Energy got trapped in space. Matter produces energy in-order to maintain its stability. That may be a chemical reaction, a nuclear reaction or even annihilation. This released energy may contain light energy and so light is produced.\n\n  There are different theories to explain what is light.\n\n1. Newtons Corposcular theory - Light is a stream of corpusles (small balls) - and thus exhibit a particle nature.\n\n2. Hygen's Wave theory - Light is comprised of compressions and rare-fractions and thus exhibit a wave nature.\n\n3. Maxwell's Electro-Magnetic theory - Light is a combination of electrical and magnetic field perpendicular to each other - travells in a straight line in a constant speed.\n\n4. Max- Plank's Quantum theory - Light cotains packets of energy - called photons. The packets are called Quanta\n\nThese theories are quite old and some how relevent even in theses days. Today we know that light exhibits both particle and wave nature.\n\nLight exists for ever. - It is never created nor destroyed.\nIt only changes its form.
286304
Yeah man...light is one of the most energetic forms that we witness. Light actually has many types of energy, just like most other things. \n\n1) Photons of light (of a suitable frequency are capable of imparting enough momentum to an electron in a metal so that the electron leaves the metal's surface. This is known as the photoelectric effect and the credit for it's knowledge goes to Mr.Einstein.\n\n2) Light has heat energy, and therefore thermodynamic value. You'll see that if you stand in the sun too long, you will be hot. \n\n3) The thermodynamic energy of light causes photochemical reactions, such as the radicalisation of halogen atoms, or the redox reactions of alkyl halides. \n\nI cannot be too sure of my satisfaction quotient with this answer because your question overlays so many fundamental concepts of light. For example, you wouldn't ask a rolling ball, "Excuse me sir, but how much energy do you really have?" The ball will snicker because you have not specified WHAT KIND OF ENERGY you want from the ball. Now, if you were to ask, "Excuse me sir, what is your KINETIC energy?", the ball would happily answer that it would be half of its mass multiplied by the square of its velocity. \n\nOne of the kinds of energy does involve a mass parameter and that would be the photoelectrical energy of light. This energy functions on the sound premise that linear and angular momentum are conserved, and since light has dual (mass-wave) nature, this kind of energy does involve mass. \n\nWe know that the energy of a photon of frequency v is E=hv where h is Planck's constant. We also know that the energy of a photon in relation to its mass is E=mc^2. THus we can say:\n\nmc^2 = hv.\n\nAll right, here is a clear answer, which I just realized. \n\nOne photon of light has the above mentioned amount of energy, and therefore a ray of light will have the energy of how many ever photons are in the ray of light. \n\nSo for n photons, energy of the ray of light is nhv. \n\nNow THIS nhv can be CONVERTED into all of the forms mentioned above. Light has energy which is capable of doing different kinds of work. \n\nForgive me for the error of thinking that light has different forms of energy. It has one form of energy which can be CONVERTED into different forms of energy. Phew....\n\nI really must thank you as this was a learning process for me too.\n\nAyerhs.
991
Light has nothing to do with space. It is a property of the electromagnetic field when this field is undergoing changes. from its point of origin, this field radiates out into space in all directions. It is invisible, but can be felt by charged particles. When this field is changed, for instance by suddenly altering the position of its emitter, a kink develops in the field which propagates out into space at the speed of light. Under the right circumstances of acceleration, this kink becomes electromagnetic radiation - light. So space simply acts as a passive container for the electromagnetic field, which in turn is the 'medium' in which light exists.
231769
Actualy, I am an expert in this field, having a Ph.D. in Optical Sciences.\n\nI don't believe light is a particle, exactly.  It is a quantization of energy, but not really like a particle.  If it were a particle it would explain how it can propagate across nothingness.  The existence of something in space would just get into its way, so the nothingness only helps light to propagate.  But a particle implies rest mass and other physical properties which light does not have.\n\nI don't believe that empty space is something, contrary to the way some people interpret Einstein.\n\nI don't believe it is action at a distance.  Light takes a finite amount of time to cross space.  The action occurs where the light is.\n\nThe question was more of a problem when light was considered to be merely a wave.  A wave needed a medium to disturb or propagate across.  Sound moves molecules about as it propagates.  But light only bears a resemblance to a wave in the way it behaves.  It is not like a classical wave.\n\nThe best way I can think of to explain it is to understand that an electromagnetic wave carries with it its own medium.  The electric and magnetic fields oscillate, feeding on itself, so to speak.  The energy is launched into space and perpetuates itself according to the laws of physics.
368112
If you shine a flashlight in a dark room, the beam of light must hit an object in order for you to see it. If there is nothing to obstruct the light, then you will still see a dark room despited the flashlight. The same is with the sun, the planets are visible because they obstruct the light and reflect it back to our eyes. Everything else is black because there is nothing there.
363047
There is no objective evidence of God's existance. At least not in any form that would satisfy the scientific method. But I think we need to approach the existance of God in another way, something similiar to the way that we might approach seeking evidence for say, dark matter.\n\nWe don't know what dark matter is because we haven't seen it. But we know that there's something out there that creates a certain effect in the universe, and we call it dark matter. But what is it? No one knows.\n\nGod's existance is really a matter of what is most likely, or least likely. If we look closely at all the constituents of life and the universe, just in terms of what science and philosophy are able to approach, then there are a number of markers that we can investigate, asking the question, "What is most likely responsible for this"?\n\nThere's work going on in the area of quantum mechanics (quantum physics) that gives us some interesting insight into consciousness and the role it plays in the physical universe.\n\nIf we apply mathematics in the form of statistical analysis to certain "random events" in nature, we're left with the realization that the odds of certain processes happening strictly on a random, or chance basis, is so incredibly small as to be non-existant.\n\nIf we thoroughly weigh the two alternate theories to do with the beginnings of life on Earth (biogenesis vs abiogenesis, or life from life vs life from non-life), apply modern biochemistry or Mathematical analysis to that... we again face some interesting insights into the question of a conscious Creator vs a dead universe.\n\nI'm not going to tell you what you should or should not believe. All I'll say is that there's religious dogma and there's scientific dogma. Both are limited, both are invested in a particular worldview. Theology and philosophy ask pertinent and important questions and provide important insights, as does science and rationalism. Don't embrace one and reject the other. Rather utilize all the ways in which we, as human beings, are able to discern relevency, the nature of life and the relatedness of existance.\n\nIf we have an agenda going in, then we'll fulfill that agenda. But if we truly care about what's true, then we'll adapt our thinking and understanding to what we discover.\n\nAnd please keep this in mind; if we think we've arrived, we have nowhere to go.
213370
Ernie... I love this question..  it rocks.\n\nThe answer, however, is going to be just a little dissappointing.\n\nAs I'm sure you know, all light is both a particle and a wave; it is a form of nearly pure energy.  As we know from theoretical physics, energy can never be created, nor can it be destroyed.  It just changes forms.  According to the third law of thermodynamics, energy always goes from higher to lower forms when left on its own, the lowest form of energy often being considered to be heat.  And that's where your wandering, amazing laserlight goes, it turns to heat.  \n\nWhy?\n\nBecause your room of mirrors is completely imperfect.  Your mirrors are dismally inefficient reflectors of light, and the room is full of air.  Household mirrors actually reflect less than 25% of the light energy that shines on them back to you.  Lab quality mirrors made for laser work are, I believe, in the high 80% to low 90% reflectivity efficiency range.  Every time your beam hits a mirror surface and bounces off, it looses more of its energy to heat..  just as it does as it passes thrugh every atom and molicule that makes up the air in the room as well.  Your laser might make it one or two 'miles' of beam length in the room before it is bouncing around.. which would make for thousands of beams.  But, since light travels at 186,000 miles per second, your two mile beam lasts 1/93,000th of a second after you turn the power off before it's gone.  So, it DOES keep going.. but not long enough for you to percieve it.\n\nSo, IF you had perfect mirrors, IN a perfect sphere (remember; you couldn't have any corners!) a COMPLETE vacium inside it with NO particles of dust of ANY kind, and a way to fire the beam into the amazing sphere without leaving any void for energy to escape...  your theory would work, if all that were PERFECT.  But; the biggest catch would be; you could never know if it were working!  Because to find out; you would have to have a void in the sphere to see or measure it...  and measuring any energy source draws energy from it.. so, there goes your light again.\n\nSo, that's why, but it's still a great question.  Theoretical Physics is full of stuff like that...  and thinking about it will turn your brain into silly putty for days.  Keep 'em coming, Ernie..  you've got a great future if you keep your mind working like that.
502472
There are basically 4 theories of light\n\n01. The Corpuscular Theory of Light\n02. The Wave Theory of Light\n03. The Electromagnetic Theory of Light\n04. The Quantum Theory of Light\n\n\n01. The Corpuscular Theory of Light\n-----------------------------------------------\nNewton proposed this theory that treats light as being composed of tiny particles. We use this theory to describe reflection.   While the theory can explain the primary and secondary rainbows, it cannot explain the supernumerary bow, the corona, or an iridescent cloud.\n\n\n02. The Wave Theory of Light\n---------------------------------------\nProposed by Huygens, this theory describes light as waves that spread out from the source that generates the light.   Each color is a different wavelength. Supernumerary bows are explained by assuming that light is a wave.\n\n\n03. The Electromagnetic Theory of Light\n----------------------------------------------------\nMaxwell's theory describes light as having electric and magnetic properties--electromagnetic waves. It is an improvement over the wave theory in that it explains how light is generated.   Visible light is only one type of electromagnetic wave. This theory is very math intensive.\n\n04. The Quantum Theory of Light\n-------------------------------------------\nThis theory is more mathematical than Maxwell's equations! It is similar to the corpuscular theory of Newton, except that instead of describing light as particles, light is composed of 'packets of energy' or photons. The energy of the photon determines the color \n\nThe dual theory of light says that it has corpuscular as well as wave properties.\n\nThe speed of light is determined as follows\nVelocity = Frequency x Wavelength\n\nTransparent Objects are  those which pass light through them. Opaque objects are those which doesn't pass light through them.  Translucent objects are between them.
264524
if light is thr then where is dark?
174577
The most difficult part of understanding things that happen at the microscopic and nanoscopic scale is that a lot of the rules that apply in our everyday lives simply don't work with elementary particles.  If you try to visualize these things, you'll probably end up with some wrong conclusions.\n\nThat said, light waves are fundamentally different from any other wave, such as water, sound, etc., because they do not travel through a medium.  A sound wave travels through air molecules, a water wave travels through water, but a light wave doesn't travel through anything.  To make matters even more confusing, light also has particle-like properties, yet it has no mass and no molecular weight.  A light particle, or photon, is considered an elementary particle, like an electron, proton, or neutron, so it has no molecular make-up, either.\n\nWaves that travel through a medium also do not have a molecular make-up.  Think of a Slinky, for instance.  If you shake one end of the Slinky, a wave travels through the Slinky to the other end, but there's no molecule form for that wave.  The wave basically just energy traveling down a line.  One molecule pushes another molecule pushes another molecule and so on and so on.
494316
Light isn't even physical, it is a form of energy made up of sub-atomic particles called Photons. Photons aren't even a form of matter, so it wouldn't be solid, liquid, gas, plasma, or any other kind of Phase (those are the only 4 known phases). Good examples of Gasses at normal room temperature would be Nitrogen, Hydrogen. Oxygen, Carbon Dioxide, and Methane.
10489
Regular light. It is not a lazer or any special kind of light, just "light". It is probably generated by a specialized piece of equipment, but it is just light - photons. It probably doesn't contain ultra violet light like sunlight, it is probably closer to artificially created light like that from a lightbulb.
550857
light is (in a nutshell) waves of energy. Waves (in general) travel in a straight line. stars are so far away that not much of their energy or waves hit the planet.
81446
LASER is the acronym for "Light Amplification by Stimulated Emission of Radiation".  It is, first, a process that is explained by quantum mechanics and statistical mechanics.  At this point, it has come into common use, and can also refer to either the light or the device used to produce this type of light.  It does not have a higher energy than light produced by other means, as the energy only depends on the frequency of light.  It does have a higher intensity concentrated into a smaller area, and much higher coherency than light from the sun or a light bulb.\n\nAlso, all light, regardless of how it is produced, travels at approximately 300,000 km/sec in a vacuum.  That value does not differ from one type of light to another, or one color of light to another.
212104
light cannot directly produce sound, but audible sound can be produced as a result of the rapid heating and expansion of the surrounding air of a powerful light beam.\nan example of this is thunder and lightning.
643521
Light DOES always travel in a straight line.  It is true that close to a massive object the light may 'appear' to bend, but this is simply because mass bends space - a straight line through curved space is still a straight line.  So the reason that light travels in a straight line is because a straight line is actiually DEFINED as the path taken by a beam of light!
64046
in our everyday life, all waves require a medium to travel in.  sound waves, water waves, you name it.\n\nso when it was discovered that light was a wave, and could even travel across a vacuum, there was no medium in the vacuum for the wave to travel in!  the ether was proposed to explain this - an invisible fluid-like substance that permeates all the universe, and it is through this fluid that light waves move.  essentially the question was:  "if light is a wave, what is waving?"  the ether was the answer.\n\nok, so that's all well and good, and nobody knew whether it was true or not for a long time.  \n\nhowever michelson and morley did an experiment in 1887 that pretty much showed that there was no ether, and that light therefore could be understood as not requiring a medium.  this understanding has been borne out by many other experiments that are consistent with an absence of the ether.\n\nhere are some cool pages that explain the essentials of the michelson-morley experiment:\nhttp://galileoandeinstein.physics.virginia.edu/lectures/michelson.html\nhttp://scienceworld.wolfram.com/physics/Michelson-MorleyExperiment.html