Are forces subject to the doppler effect?

In summary, it seems that the amount of work done on the sail by previous photons reduced the amount of work that future photons coming from the same source and direction could add to it, that is, from the frame of reference of the sail.
  • #1
kmarinas86
979
1
I know that photons hitting a solar sail can add energy to that sail.

I know that photons are gauge bosons.

I know that gauge bosons are thought to be the carriers of fundamental forces.

If a solar sail were gaining speed to a point where it reached relativistically with respect to the power source, I know that an observer on a solar sail would observe a reduction of the force on that solar sail.

Is not the same essentially true for any massless gauge boson?

It seems that the work done on the sail by previous photons reduced the amount of work that future photons coming from the same source and direction could add to it, that is, from the frame of reference of the sail.

It would seem that the actual amount of work done on the sail, from the frame of reference of the sail, would be less than the energy expended by the source which produced the photons.

Is this all correct?
 
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  • #2
kmarinas86 said:
Is not the same essentially true for any massless gauge boson?
It's true for any massless particle. It's also true for massive particles, although the amount of reduction would be different.

kmarinas86 said:
It seems that the work done on the sail by previous photons reduced the amount of work that future photons coming from the same source and direction could add to it, that is, from the frame of reference of the sail.
Yes, this is correct in an inertial frame that's momentarily co-moving with the sail (but not in the Earth's frame).

kmarinas86 said:
It would seem that the actual amount of work done on the sail, from the frame of reference of the sail, would be less than the energy expended by the source which produced the photons.
You could define three frames: E = the frame of the earth, C = an inertial frame that's momentarily co-moving with the sail at some later time, S = a frame accelerating along with the sail.

In C, there is no mismatch between the sun's energy output and the work done on the sail, since the sun is emitting photons that are Doppler-shifted to a lower energy.

In S, we have much bigger issues with conservation of energy than the ones involved in the solar sail. For instance, the sun is rapidly gaining huge amounts of kinetic energy.
 
  • #3
bcrowell said:
It's true for any massless particle. It's also true for massive particles, although the amount of reduction would be different.


Yes, this is correct in an inertial frame that's momentarily co-moving with the sail (but not in the Earth's frame).


You could define three frames: E = the frame of the earth, C = an inertial frame that's momentarily co-moving with the sail at some later time, S = a frame accelerating along with the sail.

In C, there is no mismatch between the sun's energy output and the work done on the sail, since the sun is emitting photons that are Doppler-shifted to a lower energy.

In S, we have much bigger issues with conservation of energy than the ones involved in the solar sail. For instance, the sun is rapidly gaining huge amounts of kinetic energy.
In the Earth frame wouldn't the acceleration derived from the photonic reflection energy also drop off as the sail approached c ,?? to the point where there would be no measurable increase in v from further light reflection?
On the increase in the Sun's relative kinetic energy isn't this a sort of ubiquitous problem? Inherent in any accelerating system from a relativistic perspective?
Or am I just not getting your point??
 

1. What is the Doppler effect?

The Doppler effect is a phenomenon where the frequency and wavelength of a wave appear to change when there is relative motion between the source of the wave and the observer. This effect is commonly experienced with sound waves, such as the change in pitch of a siren as an ambulance passes by.

2. How does the Doppler effect relate to forces?

The Doppler effect can affect forces in the same way that it affects waves. If there is relative motion between the source of a force and the observer, the perceived strength of the force will change due to the shift in frequency. This can be seen in the change in gravitational force between two objects as they move towards or away from each other.

3. Are all forces subject to the Doppler effect?

No, the Doppler effect only applies to forces that are transmitted through waves. This includes electromagnetic forces, such as light and radio waves, and mechanical waves, such as sound waves. Other types of forces, such as friction and tension, are not subject to the Doppler effect.

4. How does the Doppler effect impact our understanding of forces?

The Doppler effect can provide valuable information about the motion and relative positions of objects that are exerting forces on each other. By studying the changes in frequency and wavelength of waves, scientists can make observations and predictions about the forces at work in a given system.

5. Can the Doppler effect be used to measure forces?

Yes, the Doppler effect is commonly used in various scientific fields, such as astronomy and meteorology, to measure forces. By analyzing the changes in frequency and wavelength of waves, scientists can determine the magnitude and direction of forces acting on objects in motion.

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