- #1
San K
- 911
- 1
why can information not be transmitted via phase velocity (of a matter wave)?
can we not change the phase at will?
can we not change the phase at will?
Bill_K said:Yes, but the change won't keep up with the phase!
Information cannot be transmitted via phase velocity because it violates the principles of causality and relativity. Phase velocity is the speed at which a specific phase of a wave, such as the crest or trough, travels. This means that the wave is not actually moving, but rather the phase is shifting at a constant speed. Therefore, it is not possible to transmit information through phase velocity as there is no actual movement of the wave.
Yes, information can be transmitted through other types of velocity, such as group velocity. Group velocity is the speed at which the overall shape of a wave packet, which contains multiple frequencies, travels. This allows for the actual transfer of energy and information as the wave packet moves through a medium.
Phase velocity and group velocity are related through the dispersion relationship, which describes how the phase and group velocities change with frequency. In some cases, the two velocities may be equal, but in most cases, they are different. This is why it is important to consider both velocities when analyzing wave propagation and information transmission.
The medium plays a crucial role in information transmission through the velocity at which waves travel. Different materials have different properties, such as density and elasticity, which affect the speed of a wave. This can impact the phase and group velocities, and therefore, the ability to transmit information. For example, sound waves travel faster in solids than in gases, making it easier to transmit information through solids.
There are some theoretical exceptions where information may be transmitted through phase velocity, such as in certain types of metamaterials. These materials have unique properties that allow for the manipulation of wave propagation and the potential for information transmission through phase velocity. However, this is still a topic of research and has not been successfully demonstrated in practical applications.