Idle Photons (motionless relative to the Earth's surface?)

In summary: TL;DR Summary: Photon MotionCan a photon ever be motionless relative to the earth's surface? Did it accelerate from 0 mps to 186,000 mps?No* and no*.
  • #1
James William Hall
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TL;DR Summary
Photon Motion
Can a photon ever be motionless relative to the earth's surface? Did it accelerate from 0 mps to 186,000 mps?
 
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  • #2
James William Hall said:
TL;DR Summary: Photon Motion

Can a photon ever be motionless relative to the earth's surface? Did it accelerate from 0 mps to 186,000 mps?
No* and no*.

*With relative velocity being defined through parallel transport along any arbitrary but given path rather than as a coordinate speed.
 
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  • #3
James William Hall said:
TL;DR Summary: Photon Motion

Can a photon ever be motionless relative to the earth's surface? Did it accelerate from 0 mps to 186,000 mps?
This is really a Quantum Mechanics question. In SR the photon is simply a massless particle that may take part in particle collisions. But, the theory does not go any deeper that that and there is no theory on how the photon appears and no implication that it accelerates from rest.

In Quantum Electrodynamics, the photon is the quantum of the Electromagnetic field. It's not a point particle at all and a concept like "acceleration from rest" is a classical notion that has no place in the theory.
 
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  • #4
Note: my response in #2 was classical, basically interpreting "photon" to mean "pulse of light". @PeroK 's post #3 was quantum interpreting "photon" to actually mean "photon". So there will be some inconsistencies, just pick the answer that uses the meaning of "photon" that you intended.
 
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  • #5
Thank you both for your balanced explanations.
 
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  • #6
Photon in vacuum clearly cannot be stopped. If you Doppler shift it, its frequency changes... but you will find its speed unchanged.
How about photon in medium? Could you observe a photon in a medium such that the medium is moving relative to the observer/Earth surface in direction and with velocity opposite and equal to the speed of photon relative to the medium?
Lene Vestergaard Hau achieved some impressively big indices of refraction in media such as Bose condensate.
Also, photon cannot really "accelerate from rest". Indeed consider the basic limiting case of electromagnetic "waves" with zero frequency. On that limit, what we get is electrostatic and magnetostatic fields... which do not propagate, do not carry energy, momentum or angular momentum and are not quantized into real photons, only virtual ones. (Precisely how is electrostatic field expressed through the virtual photons, though?)
 

1. What are idle photons?

Idle photons are photons that are not in motion relative to the Earth's surface. They are essentially stationary and do not contribute to any form of energy or movement.

2. How are idle photons different from regular photons?

Regular photons are constantly moving at the speed of light, while idle photons are not moving at all. Regular photons also have energy and contribute to various forms of electromagnetic radiation, while idle photons do not.

3. Can idle photons be detected?

No, idle photons cannot be detected because they do not interact with matter or produce any form of energy. They essentially have no physical presence.

4. What causes photons to become idle?

Photons become idle when they are in a state of equilibrium, meaning they have no net force acting on them. This can happen when they are trapped in a material with a high refractive index or when they are in a vacuum.

5. Why are idle photons important to study?

Idle photons may seem insignificant, but they play a crucial role in understanding the behavior of light and the properties of materials. They also have potential applications in technologies such as optical trapping and optical tweezers.

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