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

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• James William Hall
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*.

#### James William Hall

Gold Member
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?

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.

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.

topsquark and Dale
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.

Thank you both for your balanced explanations.

berkeman
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 particles of light that appear to be motionless relative to the Earth's surface. They are also known as stationary photons.

## 2. How can photons be motionless?

Photons are particles that travel at the speed of light, which is incredibly fast. However, when observed from a stationary point on the Earth's surface, their motion may appear to be minimal or even non-existent due to the Earth's rotation and the observer's perspective.

## 3. Are Idle Photons actually stationary?

No, Idle Photons are not actually stationary. They are still traveling at the speed of light, but their motion may appear to be motionless relative to the Earth's surface.

## 4. How do Idle Photons affect our perception of time?

Idle Photons do not directly affect our perception of time. However, their motionlessness does play a role in the phenomenon of time dilation, where time appears to pass differently for objects in motion compared to those at rest.

## 5. Can Idle Photons be used for anything?

Idle Photons are currently not being used for any practical purposes. However, they are studied and used in various experiments in physics to better understand the behavior of light and its interactions with matter.