Does photon loose energy/mass during travel?

In summary, a photon can lose energy as it travels through space, known as redshifting, due to the expansion of the universe. However, it does not lose mass as it is pure energy. Factors that can cause a photon to lose energy include interactions with matter, gravitational redshift, and the expansion of the universe. On the other hand, a photon can gain energy through blueshifting when traveling towards a source of gravity or when scattered by high-energy particles. The speed of light indirectly affects the energy of a photon during travel through its relationship with frequency.
  • #1
San K
911
1
Let's say we track a photon... starting from sun and reaching earth.

When the photon moves through space (maybe because there is vacuum) it looses no/little energy. Now... when it enters atmosphere?

When it goes through glass plate? or through ocean or through water vapour? Does it slow down?

Is there not resistance?

however a quanta is the lowest possible energy amount, thus is can only be all or nothing?
 
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  • #2
https://www.physicsforums.com/showpost.php?p=899393&postcount=4
 
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1. Does a photon lose energy as it travels?

Yes, a photon can lose energy as it travels through space. This is known as redshifting, which occurs when the wavelength of the photon increases, indicating a decrease in energy. Redshifting is caused by the expansion of the universe, and it is one of the fundamental principles of cosmology.

2. Does a photon lose mass during travel?

No, a photon does not have mass to lose. According to Einstein's theory of relativity, mass and energy are equivalent and can be converted into each other. As photons are pure energy, they cannot lose mass during travel. However, they can lose energy as discussed in the previous question.

3. What factors can cause a photon to lose energy?

There are a few factors that can cause a photon to lose energy during travel. These include interactions with matter, gravitational redshift, and the expansion of the universe. When a photon interacts with matter, such as during absorption or scattering, it can lose energy. Gravitational redshift occurs when a photon travels through a region with a strong gravitational field, causing it to lose energy. Lastly, as the universe expands, the wavelength of photons increases, resulting in a decrease in energy.

4. Can a photon gain energy during travel?

Yes, a photon can gain energy during travel through a process called blueshifting. This occurs when the wavelength of the photon decreases, indicating an increase in energy. Blueshifting can happen when a photon is traveling towards a source of gravity or when it is scattered by high-energy particles.

5. How does the speed of light affect the energy of a photon during travel?

The speed of light, which is a constant in the universe, does not directly affect the energy of a photon. However, the energy of a photon is indirectly related to its frequency, and the speed of light affects the frequency of a photon. According to the equation E=hf, where E is energy, h is Planck's constant, and f is frequency, as the frequency of a photon increases, so does its energy. Since the speed of light is the product of frequency and wavelength, it indirectly affects the energy of a photon during travel.

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