what will be the speed seen by one photon of other in a beam?
80793
According to reletivity, the transformed velocity is zero.\n\nPhotons will see each other at rest,\n\nAlso it is interesting to know that it takes no time for photones to travel all the world if ask them.
851776
E=mc^2\n\nwhere \n E is in joules or kg·m²/s²,\nm is in kilograms, and \nc equals speed of light, in meters/sec (approx 3*10^8)
426222
The speed of light is the same no matter where it is. It is 299,792,458 meters per second.
144703
No, one of the defining properties of a photon is that two or more are capable of simulatenously existing at the same co-ordinates. As such they can't possibly intercept each other or cause refraction since that requires either that they bounce of one another or else slow one another down. Neither is possible if they are to continue being capable of coexiting at the same location.\n\nPhotons can certainly interfere with each other, but only to the extent of increasing or decreasing amplitude, not wavelength or direction. At best you could theoretically reduce the amplitude of one source to zero, thus making it cease to exist, or alternatively boost the amplitude for a stronger signal.
791590
E = m x c^2,\nso \n\nmass = Energy / c^2 (speed of light squared)
737785
I'll let you do the calculation, but the equation you need is:\n\nE = hc/lambda \n\nwhere h is Planck's constant, c is the speed of light in m/s and lambda is the wavelength of the light (in meters). You can find the rest of the numbers in your text book, I'm sure...
886711
The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning "swiftness". It is the speed of all electromagnetic radiation in a vacuum, not just visible light.\n\nIn metric units, c is exactly 299,792,458 metres per second (1,079,252,848.8 km/h). Note that this speed is a definition, not a measurement, since the fundamental SI unit of length, the metre, has been defined since October 21, 1983 in terms of the speed of light: one metre is the distance light travels in a vacuum in 1/299,792,458 of a second. Converted to imperial units, the speed of light is approximately 186,282.397 miles per second, or 670,616,629.384 miles per hour, or almost one foot per nanosecond.\n\nThrough any transparent or translucent material medium, like glass or air, it has a lower speed than in a vacuum; the ratio of c to this slower speed is called the refractive index of the medium (the actual speed is not affected, the speed of light is constant, the fact that the light is reflected around inside the glass will make a greater amount of time necessary for it to reach the next point). Changes of gravity, however, warp the space the light has to travel through, making it appear to curve around massive objects. This gives rise to the phenomenon of gravitational lensing, in which large assemblies of matter can refract light from far away sources, so as to produce multiple images and similar optical distortions.\nclick here:http://en.wikipedia.org/wiki/Speed_of_light#Overview
90556
Always exactly the same speed, c = 299 792 458 meters/second, no acceleration or deceleration or anything.\n\nThe *apparent* speed of light through glass is less than c, but that is because the photons (the light) bounce off all the atoms and that slows down the speed through the glass. The speed of light from one atom to the next is exactly c.\n\nAlso, sometimes you will read about experiments where the popular press version says some bunch of light has been made to faster than c, but this is just the phase speed and so isn't quite the same thing. You can't send any information faster than c with this method.\n\nThere is an apparent something that goes faster than light in what is called the EPR-effect, a wierd property of quantum mechanics often misleadingly called "quantum teleportation," but again, no information travels faster than c.\n\nThere are hypothetical particles called tachyons which *always* go faster than light - they can't go slower. But no evidence for these have been found and most physicists think they can't exist.\n\nAs for warp drives and other faster-than-light science fiction type things, that, in my opinion isn't possible. Certainly everything we know about physics and the universe now says it is impossible, and it is unlikely that any future theory will show we are so wrong now that we missed this one. Also if FTL is possible then you can have a sort of time travel, and then cause and effect get ruines and, well, its a mess.\n\nBe glad that c is absolutely the same to all observers in every situation - the universe wouldn't work without it.
252752
When the lightwave is traveling in a vacuum, there is no change regardless of the wavelength.  All light travels where there is no matter at roughly 300,000 km/sec.\n\nFor other materials, you would have to look at the dispersion relation for that material.  This will tell how the speed of light at different wavelengths is affected by the material.
447577
enery equals mass times the speed of light squared
547699
Its a myth that thought is particularly fast- We can measure the speed that signals travel along nerves, in the spinal cord, brain, etc, and it's around 20-60 meters/second.  Not nearly as fast as light (186,000 miles/second).  Photons don't "accelerate" to the speed of light-that speed is a stable property of photons, thus they are going that speed at the instant they are created-they dont start from motionlessness and speed up.\n*edit* Mich is right-light can be slowed and accelerated, but again, a photon upon creation does not accelerate to it's maximum speed (whatever that is given the medium that it's in)-it starts life going at that speed.  All light does *not* travel at 186,000 miles/sec- that is the speed of light in a vacuum-the speed varies with the medium that light is traveling through.  The speed of light through normal clear glass, for example, is around 120,000 miles/sec.
1149311
Light does not intend to travel at the speed of light\nLight travels at a certain speed, it actually does not know its speed.\nWhen scientists measured this speed they found it 299 792 458 m / s or about 186000 miles per second \nso they make it fixed term, refereed as "the speed of light", used it in other physical equations...\nthen it "speed of light" became a famous term. \nBut Light still does not know that they called its velocity as the light speed..\nAnd I think it will not know!
353005
No. But, from the POV of the photon, they are everywhere along the path of the photon at once. See the answer on "lorentz contraction", because it's right, but I just wanted to clarify that photons are not, in fact, *everywhere* at once.\n\nOh, and from the POV of any subluminous velocity, no, they propagate at the speed of light, naturally.
495659
The accurate speed of light is 299,792,458 m/s.
410856
Engery\nMass\nc is the speed of light (why c? I don't know does anybody else?)
592101
The negative of the Speed of Light.
465629
All light has a velocity of "c."  c is ~ 3*10^8m/s.  With this knowledge you can say that frequency is the inverse of time/distance.  Thus, you can use the formula C(meters/sec) / Freq.(cycles/sec) = Wavelength(meter/cycle) to solve the question.\n\nDo your own work from there.