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I understand that light travels in a straight line unless gravity says otherwise. However, if it were theoretically possible to keep the energy in a photon without having any directional movement, what would happen? Would the photon dissipate and just transfer its energy to a nearby particle?

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    $\begingroup$ Non-moving photons are not a mainstream physics concept, at least not in vacuum. They are an oxymoron — a contradiction in terms — like a square circle. $\endgroup$ – G. Smith Sep 15 at 19:01
  • $\begingroup$ Are you satisfied with zero average velocity? $\endgroup$ – Superfast Jellyfish Sep 15 at 19:53
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Can a photon vibrate without any velocity or directional movement; Can it vibrate without moving?

So you are essentially asking:
Can a photon have a non-zero frequency $\omega$ while having a zero wave-number $k$ ?

The answer is:
No, it can't, because for photons in vacuum we have the following dispersion law $$\omega = c k \tag{1}$$ where $c$ is the speed of light. This linear dispersion law is equivalent to saying a photon has zero rest-mass.

This would be entirely different if the photon would have a non-zero rest mass $m$. Then the dispersion law would be $$\omega^2 =c^2k^2 + \left(\frac{mc^2}{\hbar}\right)^2 \tag{2}$$ where $\hbar$ is Planck's constant. (You can find more about massive bosons (in contrast to massless bosons) by searching for "Proca action" or "Proca equation").

From (2) we can see: For massive photons at rest (i.e. $k=0$) we would have $$\omega_\text{rest}=\frac{mc^2}{\hbar}$$ A massive photon at rest would just sit there and keep its energy.

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Empty space is the condition for the existence of photons. Even on an atomic scale, photons exchange energy between the subatomic particles of gases, liquids or solids, which always (by their very nature) have a distance between them.

The only thing that influences photons during their way through vacuum is gravity. The geodesic path of EM radiation is influenced by masses, it is bended towards it. The bending is the same for EM radiation of any wavelength. Means, the speed of light in a given point of space is a constant value.

Last but not least the gravitational potential influences the speed of light. At higher potential (near masses) the speed of light slows down - seen from a third point -. If the light in the vicinity of a black hole were observed from Earth, the speed of light would be measured with a lower value than on Earth.

Long narrative, briefly summarized. Light needs empty space to come into existence. And light then moves at a specific speed. Standing light in a vacuum is not provided by nature.

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