Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Acceleration of the Photon and the shape of it's wave

  1. Oct 25, 2009 #1
    Hello Again

    Regarding photons: Is there any small transient time lag or "ramp up" between their point of emission and their full speed. In other words do they go Zero to 186,000 miles per second in all of an instant? And have there been any experiments to see if this is an instantaneous full speed acceleration?

    Also I have several differing visual representations in my head regarding the shape of the wave aspect of a photon. And I am not 100% clear on the exact shape and energy of this wave as it accompanies the photon on it's "journey."

    Say if a single photon was shot down a hypothetical hole (say two photons wide) that was drilled through a solid lead block, would the full wavefront of the photon as it exits this tiny tunnel be measurable just a microscopic distance from the perpendicular surface of the exit point and various distances along the surface at different distances along the exit plane from the exit hole but still a microscopic distance from the plane? In other words does a full wavefront appear the instant the photon emerges from the Hypothetical lead block, literally starting at the exact perpendicular plane of the exit point or would there be a dome like curve to the energy measured various distances from the exit point. I'm curious where the measurable wave effects of the photon would become evident along that exit plane and at various distances away from the exit point?

    For some reason I use the theoretical "two photon wide tunnel through a lead block" just to have a baseline without having any gravity or other effects which may be present in the thin aperture of a dual slit experiment if that makes any sense.

    I am not sure if the lead block example is the best example to find such a baseline depiction of the exiting shape of the wavefront of the exiting photon, maybe a totally non metallic ceramic block, but the idea is to have a surface on the other side to take measurements and reconstruct the energy "vectors" at various points and thus reconstruct the precise shape of the wave itself.

    Thank you very much in advance

    Vox
     
  2. jcsd
  3. Oct 25, 2009 #2
    Photons are emitted as waves on water - you shake the surface and the wave propagates with some velocity. No acceleration is involved in such a mechanism.

    Photon has many oscillations in it: 10000-100000, for example. It is not a point-like and it is not accelerated when emitted.

    In a transparent medium with variable n the photon can be "accelerated" and decelerated" if n varies in space: its velocity is c/n.
     
  4. Oct 25, 2009 #3
    Thanks for the response

    I'm not sure how those 10000 to 100000 oscillations are happening? As this force radiates in a direction at 186k mi per sec. it is also oscillating? at 10k to 100k hz?

    Thanks in advance
     
  5. Oct 25, 2009 #4
    Think of a surface water wave as example. It is you (or the energy difference in atom) who imposes the wave frequency. Of course, the wave propagates with some speed, the light - with c = 186000 mi/sec.

    The electromagnetic wave frequency may vary in a wide range. The LW (long-wave) radio-diapason, MW, SW, etc. The visible light wave-lengths are rather short. X-rays are even shorter because their frequencies are higher. Theoretically there is no limit on frequency. They all are possible and are determined with the source of wave.

    An electromagnetic wave of a certain frequency is a coherent beam of many photons (wave-train).
     
  6. Oct 26, 2009 #5
    You have used here a simple analogy but there is in fact acceleration involved in the speed of water waves. Its earth’s gravity. Gravity combined with the wave length gives the speed of the wave. In case of a wave in air its speed is determined by the speed of the air molecules. Therefore the question still remains: what determines acceleration and speed of light waves?
     
  7. Oct 26, 2009 #6
    The electromagnetic field is a physical reality with its own properties. The frequency is imposed with the source, the propagation occurs on its own.
     
    Last edited: Oct 26, 2009
  8. Oct 27, 2009 #7
    Quoted from Born2bwire in: Light as an EM wave.

    The way I see it is that speed of light is present at all times in this energy of the vacuum state. No acceleration/deceleration needed.
     
  9. Oct 27, 2009 #8
    What a rubbish!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Acceleration of the Photon and the shape of it's wave
  1. Photons as waves (Replies: 15)

Loading...