Physics Forums
A typical Photon packet consisting of a self propagating electromagnetic pulse is described often nowadays something like this picture
http://superstruny.aspweb.cz/images/fyzika/foton.gif
and it is propagating as typically described by this animation ..
The thing is that the electromagnetic stuff of which the wave is embedded has to move further that the overall pulse speed because it is deforming and reshaping to fit a Sinusoidal curved path , and not just the simple straight line path as could be and often is used in the extreme to describe the motion of light .
So while the pulse itself is moving as measured from a point A -- to a point B at said speed/velocity of Vc ... the waveform moment itself is propagating significantly further in the same time (covering an amplitude dependent scalar of the linear distance AB) .. i.e the velocity of the propagating wave is simply greater than c = 3x10^8 m/s .
Looking at this generalised wave form pattern , we can see the point in fact .. the pulse can be seen to travel a wavelength , but a propagating point following the 'ripple' itself is clearly traveling a considerably longer distance (amplitude dependent) in exactly the same time .
http://superstruny.aspweb.cz/images/fyzika/foton.gif
and it is propagating as typically described by this animation ..
The thing is that the electromagnetic stuff of which the wave is embedded has to move further that the overall pulse speed because it is deforming and reshaping to fit a Sinusoidal curved path , and not just the simple straight line path as could be and often is used in the extreme to describe the motion of light .
So while the pulse itself is moving as measured from a point A -- to a point B at said speed/velocity of Vc ... the waveform moment itself is propagating significantly further in the same time (covering an amplitude dependent scalar of the linear distance AB) .. i.e the velocity of the propagating wave is simply greater than c = 3x10^8 m/s .
Looking at this generalised wave form pattern , we can see the point in fact .. the pulse can be seen to travel a wavelength , but a propagating point following the 'ripple' itself is clearly traveling a considerably longer distance (amplitude dependent) in exactly the same time .