Yes, according to the theory of relativity, the wavelength of light can appear different to an observer due to two main relativistic effects: time dilation and the Doppler effect.
- Time Dilation: According to the theory of special relativity, when an observer is in relative motion with respect to a light source, there is a relative difference in the passage of time between the observer and the source. This effect is known as time dilation. As a result, the observer measures a different frequency (and therefore a different wavelength) of the light compared to a stationary observer.
If the observer is moving away from the source, the measured wavelength of light will appear longer (redshifted) compared to the wavelength observed by a stationary observer. Conversely, if the observer is moving towards the source, the measured wavelength will appear shorter (blueshifted) compared to the stationary observer.
- Doppler Effect: The Doppler effect is a phenomenon that occurs when there is relative motion between a wave source and an observer. It causes a shift in the perceived frequency (and thus the wavelength) of the wave. The Doppler effect applies to all types of waves, including light.
For light waves, if the source of light and the observer are in relative motion, the motion can cause a shift in the observed wavelength. If the observer is moving towards the source, the wavelength of the light appears shorter (blueshifted). On the other hand, if the observer is moving away from the source, the wavelength appears longer (redshifted).
Both time dilation and the Doppler effect can cause changes in the wavelength of light as perceived by a specific observer due to their relative motion. These effects have been experimentally verified and play a crucial role in various fields of physics, such as astrophysics and the study of relativistic phenomena.