Final answer:
The de Broglie wavelength of a particle changes as its speed increases and is compatible with the theory of special relativity throughout the spectrum.
Step-by-step explanation:
Relativistic de Broglie wavelength is the wavelength associated with a particle that is moving at relativistic speeds. According to the theory of special relativity, the de Broglie wavelength of a particle changes as its speed increases. As a particle approaches the speed of light, its de Broglie wavelength increases. This can be observed through experiments and is compatible with the theory throughout the spectrum.