Relativistic Doppler Effect near a Black Hole

In summary, if a person is rotating near a black hole at near the speed of light, there will be two types of redshifts: gravitational redshift and relativistic Doppler effect redshift. However, if the person starts traveling towards an observer, the Doppler effect would result in a blueshift, while the gravitational redshift would remain. It is possible for the observer to view the light at its original frequency if the Doppler effect blueshift and the gravitational redshift cancel each other out. This can be achieved by adjusting the speed relative to a nearby hovering observer.
  • #1
appot89
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TL;DR Summary
Relativistic Doppler Effect near a blackhole
Hey everyone, if I were to view a shining person rotating near a black hole at near the speed of light there would be 2 kinds of redshifts: gravitational redshift and relativistic doppler effect redshift. Right?

But, say at some point, the person is traveling towards me, then the doppler effect would result in a blueshift while the gravitational redshift would remain. Is it possible that if the doppler effect blueshift and the gravitational redshift were equal, would I view the light shining at its original frequency?
 
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  • #2
Yes.
 
  • #3
You can always adjust your speed relative to a nearby hovering observer so that your kinematic blueshift cancels the gravitational redshift, yes. It'll happen naturally at some point for an object in a circular orbit (and probably any other), if my algebra is correct.
 

1. How does the relativistic Doppler effect near a black hole differ from the classical Doppler effect?

The relativistic Doppler effect takes into account the effects of gravity on the frequency of light, while the classical Doppler effect only considers the relative motion between the source and observer. Near a black hole, the strong gravitational field can significantly alter the frequency of light, leading to extreme redshift or blueshift.

2. What is the significance of the relativistic Doppler effect near a black hole?

The relativistic Doppler effect near a black hole is important for understanding the behavior of light and other electromagnetic radiation in extreme gravitational environments. It can also provide valuable information about the properties of the black hole, such as its mass and spin.

3. How does the relativistic Doppler effect near a black hole affect the appearance of objects?

The relativistic Doppler effect can cause objects near a black hole to appear distorted or even invisible due to extreme redshift. This effect is known as gravitational lensing, and it can also create multiple images of the same object due to light being bent by the black hole's gravity.

4. Can the relativistic Doppler effect near a black hole be observed?

Yes, the relativistic Doppler effect near a black hole has been observed in several astrophysical phenomena, such as the jets of particles emitted by black holes and the accretion disks surrounding them. It can also be observed in the spectra of light emitted by objects near a black hole.

5. How does the relativistic Doppler effect near a black hole impact time dilation?

The relativistic Doppler effect can cause time dilation near a black hole, as the extreme gravitational field can slow down the passage of time for an observer compared to a distant observer. This effect is known as gravitational time dilation and has been observed in the behavior of light near black holes.

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