Does light lose energy (frequency decrease) with time?

In summary, the conversation discusses whether light traveling through space loses energy and experiences a decrease in frequency over time, and how this relates to the conservation of energy. It also mentions a cosmological theory that has since been disproven. Additionally, the conversation brings up the shifting of the universe's temperature and blackbody spectrum over time.
  • #1
mateomy
307
0
This isn't a direct homework question but it pertains to a little presentation I'm working on. I was curious because answers, to some extent, seem to be all over the place. Wanted to get the opinion of physicsforums. Does light traveling through space (assuming no interactions with other matter), lose energy and thereby experience a decrease in frequency...say, going from visible light to infrared or radio, just by the passage of time?

Thanks.
 
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  • #2
Then energy wouldn't be conserved, would it?
 
  • #3
Of course not. (completely embarrassed I didn't think of that)

Guess that settles it. Thanks.
 
  • #5
Think about this: the universe was 3000 K when it became transparent to light. Today, the temperature is below 3 K. The blackbody spectrum shifted to lower energies over time. How did that happen?
 

1. Does light lose energy over time?

Yes, light does lose energy over time. This process is known as "attenuation" or "decay".

2. Why does light lose energy over time?

This is due to the interaction of light with matter. As light travels through a medium, it may be absorbed, scattered, or reflected, which results in a decrease in energy.

3. How does the energy of light decrease?

The energy of light can decrease in two ways: through absorption, where the photons are absorbed by matter, or through scattering, where the photons are redirected in different directions.

4. Does the frequency of light decrease over time?

Yes, the frequency of light does decrease over time as it loses energy. This phenomenon is known as "redshift".

5. Can light lose energy in a vacuum?

Yes, even in a vacuum, light can lose energy through a process called "spontaneous emission". This occurs when an excited atom returns to its ground state and releases a photon.

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