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Light travels in the form of a wave.It has masless photons travelling at the speed of light.Does it mean that tha photons travels in the trajectory same as that of a wave.

akash agarwal
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  • Yes. The electromagnetic wave (a photon) is a wave of a fluctuating electric and magnetic field that is propagating in some direction in spacetime. – MaDrung Feb 13 '17 at 06:49
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    Electric field and magnetic field ossiclate perpendicular to each other and the light travels perpenicular to both so where is the photon and how does it move forward and does it move in a wave like trajectory – akash agarwal Feb 13 '17 at 06:53
  • You can Picture it as a disturbance in space time that is traveling in one direction. And like you said, the magnetic and electric fields are fluctuating in 2 perpendicular sides from value of let's say -1 to 1. But their constant fluctuation is moving in a perpendicular direction which is also a direction of a photon. The electromagnetic fluctuations in spacetime Will follow the path of a photon. – MaDrung Feb 13 '17 at 06:55
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    So where is the wave like trajectory as we can draw a conclusion that it is moving in a straight line – akash agarwal Feb 13 '17 at 06:56
  • It's like a water wave. It has a constant fluctuation of the height of the wave from 1 to -1. But the wave itself is moving in a perpendicular direction of that fluctuation. – MaDrung Feb 13 '17 at 06:57
  • See "The first ever photograph of light as both a particle and wave" here – Ng Chung Tak Feb 13 '17 at 12:53
  • "You can Picture it as a disturbance in space time [...]" You'd be wrong if you did. In both the classical and the quantum pictures. @MaDrung's first comment is correct in the classical picture: it is electric and magnetic fields that are disturbed, and that is different from space-time being disturbed. Don't confuse them. – dmckee --- ex-moderator kitten Feb 13 '17 at 16:15
  • I see how I worded it incorrectly. I meant it as a disturbance in electromagnetic field that is propagating in space time. – MaDrung Feb 13 '17 at 16:21

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Light travels in the form of a wave.

This is beautifully fitted for electromagnetic radiation with solutions of the Maxell equations, yes it has varying electric and magnetic fields.

This drawing from wikipedia for polarized light might enlighten you.

photspin

The red arrow is the direction of the maximum of the electric field which, with the perpendicular magnetic field form the classical light.

It has masless photons travelling at the speed of light.Does it mean that tha photons travels in the trajectory same as that of a wave.

No, the myriads of photons that make up the classical beam are described by their zero mass, and their spin direction. It is not waving. In the diagram above the photon is in the middle, and the relation with the classical wave is that the polarization direction of the classical wave is built up by the spins of the photons.

The myriads of photons build the classical wave by a superposition of their wave functions, which do have the electric and magnetic fields, and to understand the way this happens needs the mathematics of quantum electrodynamics.

What is "waving" for the photon is the probability of finding it at a given (x,y,z,t), which is the complex conjugate square of the wavefunction.

anna v
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