Originally posted by GeorgeBronxThe extra energy is something fundamental to light, if you do something to change its wavelength (1/frequency), it changes its energy content, plancts constant times wavelength is the energy per 'packet' of electromagnetic quanta. The energy of a photon quanta can be thought of like this: They all go the speed of light, no matter what the wavelength. So if you have a constant stream of these quanta going by some sensor then if the wavelength is shorter you get more bangs per second. Or the converse, longer wavelength means less quanta per second goes by so less total energy. Each quanta has X amount of energy depending on that wavelength, so if a spacecraft has a laser that shoots out ahead of itself, then the wavelength comes out shorter because of doppler shift so if the laser is say, green light at 500 Nm wavelength, then when the light actually leaves the craft its now, say, 100 Nm which by definition contains 5 times the energy of the original. Of course you don't have much time to get out of the way of the spacecraft if the light is coming out at full C velocity and the spacecraft is doing 0.99C!
According to Einstein's Theory of Relativity, Light passes you at C no matter what your speed. There is/would be no extra energy to accont for.
Originally posted by AThousandYoungNot quite following the logic there. There is the old tacyon idea where there is a particle with negative energy that can never go LESS than C.
That's interesting. If the energy of the photon increases as the speed of the source increases, it seems almost as if there is something that is indeed going faster...some sort of "sub photon" or something.
So far unproven no detection of tacyons yet, which doesn't prove they don't exist either. So far nothing with mass can go faster or even equal to C. So a photon cannot end up with infinite energy because it would take infinite energy for the mass of the spacecraft to get to C.
No infinite energy? Bummer. No C, much less MORE than C.
I like the wormhole idea however, connecting two widely separated points of the universe together to allow effective travel faster than C but it would be kind of skipping through the universe and avoiding all the space matrix junk that slows mass to less than C. (That which makes up space itself)
I have read some of this disscussion but I must say, all and every one of you fall for the oldest difficulty in trying to answer any problem. It is not the problem that you think it is. The problem is in the question, Occum, the medievil thinkers advice was to take a razzer to the chaff, cut through vagaries that is inherant in all language and ask the most clear and most conncise Q, only then will you be able to A the Q. Bertrum Russle and the logical posatives tryed to do just that, mathamaticly. I have no opinion either way if this is the final word, but I do think that it helps us all to side step the inherant confussion that is language.
Originally posted by fakillThat must explain the reason it took mankind 2000 years of muddlement till Big Al came along.
I have read some of this disscussion but I must say, all and every one of you fall for the oldest difficulty in trying to answer any problem. It is not the problem that you think it is. The problem is in the question, Occum, the medievil thinkers advice was to take a razzer to the chaff, cut through vagaries that is inherant in all language and ask the most c ...[text shortened]... word, but I do think that it helps us all to side step the inherant confussion that is language.
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in special relativity there is no 'special' frame of reference which can be said to be stationary. so it is not possible to say whether the space craft is travelling towards the mirror or vica verca. it can only be said that they are travelling towards each other. if the space craft fires a 500nm wave lengh laser beam at the mirror then from the perspective of anyone on the space craft stupid enough to stick their head out the window and look into the beam will see it as a 500nm beam as they have the same velocity. from the perspective of anyone at the mirror the beam will appear blue shifted (due to doppler shifting as explained above by someone) and WILL contain more energy. this light will be reflected back towards the oncomming space craft. the people in the space craft will see the beam come back and because the mirror is heading towards them the light will apear to have blueshifted again and will contain even more energy. if the space craft had a mirrior in its nose then the beam could be bounced back and fourth between them gaining energy with every bounce. At no point is it 'downshifted' (redshifted) as the space craft and mirror are moving towards one another. where does the energy come from? ... it comes from the mirror and the space craft's respective Kinetic Energy. both will slow down. light hiting a surface will create preasure. this is the principle behind solar sails.
Originally posted by googlefudgeI guess in reality such a scenerio would halt after a while because if it gains energy like that each time there will come a point where it will go from 500 NM to 50 NM to 5 NM to.5 NM (50 Angstroms)and so forth so at some point the mirror will no longer be able to reflect such high frequency waves and these X rays will penetrate the mirror never to be seen again. If it doesn't destroy the mirror, a cycle would start with a new batch of light, all the while the spacecraft is giving up kinetic energy. Not sure if this scenario is realistic though.
in special relativity there is no 'special' frame of reference which can be said to be stationary. so it is not possible to say whether the space craft is travelling towards the mirror or vica verca. it can only be said that they are travelling towards each other. if the space craft fires a 500nm wave lengh laser beam at the mirror then from the perspect ...[text shortened]... own. light hiting a surface will create preasure. this is the principle behind solar sails.
how do you know the laser would shift up to blue? mighten it go invisible? to maybe UV? thats a question i got out of this riddle.
also, just like a jet passing mach 1 causes a large boom, what do u guys reckon would happen if a large vehicle passed C? im only in yr10 so simpler words are appreciated🙂
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Light is the term we give to self reinforcing occilations of the electric and magnetic feilds. the 'colour' of light is a function of it's frequency/wavelength (number of oscilations per second/distance between waves.). the high frequency/short wavelength end of the spectrum is considered blue, and the low frequency/long wavelength end is considered red. the crossover point is in the visible spectrum where we perceive the light to change colour from red to blue, this happens in the hundred nanometer wavelengh region. red and blue shift simply refer to which direction the frequency/wavelength has moved in. light wich has been dopler shifted from UHF raidio to microwave would be considered to have been blue shifted but is still below red light in the visible spectrum (about 700 Nm) it cannot be seen by the human eye.
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Originally posted by Randalthe speed of light in a vacume and zero grav feild can't be exceeded (all currently potentially possible FTL ideas involve making the distance you need to travel shorter rather than be able to exceed light speed, this is not considered possible under current theory, which has imense evidentiary backing) however light slows down in the presense of matter and it is possible to exceed this lower speed (indeed in some materials light has been slowed to centimetres per second). when an object exceeds the local speed of light it emmits Cherenkov radiation, which is a light cone shockwave analagouse to the sonic boom of a aircraft travaling at super sonic speeds. this effect is used in the heavy water nutrino detector in canada.
also, just like a jet passing mach 1 causes a large boom, what do u guys reckon would happen if a large vehicle passed C? im only in yr10 so simpler words are appreciated🙂