Matter Waves and the Speed of Light: Exploring Wave-Particle Duality

In summary, matter waves, such as electrons, do not travel faster than the speed of light. While there may be rare instances where they can exceed the speed of light in a specific medium, they can never equal or surpass the speed of light in a vacuum. This is due to the theory of Special Relativity. While the phase speed may appear to be faster than c, it is actually dependent on the material speed and can become infinite as the material speed approaches zero. In quantum field theory, there is a possibility for particles to propagate faster than light, but this is still compatible with relativity.
  • #1
shaan_aragorn
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Why do matter waves (as in wave-particle duality) travel faster than light? How is it possible?
 
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  • #2
shaan_aragorn said:
Why do matter waves (as in wave-particle duality) travel faster than light? How is it possible?

Welcome to PhysicsForums!

"Matter waves" (such as electrons, which have a relativistic mass) do not travel faster than c (the speed of light in a vacuum). In fact they can never equal c either.

There are rare/special occasions (Cherenkov radiation) in which such a particle can exceed the speed of light in a particular medium, but it is still less than c. In particle accelerators, electrons are regularly accelerated to over 99% of c, but never all the way up to c.
 
  • #3
Another interesting thing to understand that even in such circumstances special theory is not violated since they cannot carry any information
 
  • #4
shaan_aragorn said:
Why do matter waves (as in wave-particle duality) travel faster than light? How is it possible?

It is only the phase speed which appears to move faster than c. This apparent
speed depends on the actual material speed v like, phase speed = c2/v.

This means for instance that the phase speed becomes infinite as the
material speed becomes zero! This may sound all weird but the explanation
is actually simple and beautiful. It's the theory of Special Relativity at work.

I wrote an illustrated explanation which you can read here:

http://www.chip-architect.com/physics/deBroglie.pdf

You'll find it as well as you google for: relativistic de broglie wave packet



Regards, Hans
 
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  • #5
Nice paper!

That's a very interesting and informative paper - thanks!
Ed
 
  • #6
In QFT, there is a nonzero probability for a particle to propagate faster than light (or, as they say, "outside the light cone"). Read the causality section 2.4 in Peskin and Schroeder for how this is nevertheless compatible with relativity.

Carl
 

1. What is the relationship between matter waves and the speed of light?

The relationship between matter waves and the speed of light is described by the theory of wave-particle duality, which states that particles, such as electrons, can exhibit both wave-like and particle-like behavior. This means that matter, including particles, can also have a wavelength and frequency, just like light does. The speed of light is a fundamental constant that plays a crucial role in determining the properties and behavior of matter waves.

2. How do matter waves differ from classical waves?

Classical waves, such as sound waves or water waves, are made up of a disturbance in a medium, such as air or water. Matter waves, on the other hand, are not made up of a disturbance in a medium, but rather describe the probability of finding a particle in a certain location. This means that matter waves are not physical waves like classical waves, but rather mathematical representations of the behavior of particles.

3. Can matter waves travel faster than the speed of light?

No, matter waves cannot travel faster than the speed of light. According to Einstein's theory of relativity, the speed of light is the maximum speed at which any form of matter or energy can travel. This means that matter waves, just like particles, cannot travel faster than the speed of light.

4. How does the speed of light affect the behavior of matter waves?

The speed of light plays a crucial role in determining the behavior of matter waves. It is a fundamental constant that is used to calculate the wavelength and frequency of matter waves. Additionally, the speed of light also determines the maximum speed at which matter waves can travel, as well as their energy and momentum.

5. What experiments have been conducted to confirm the wave-particle duality of matter?

Several experiments have been conducted to confirm the wave-particle duality of matter, including the double-slit experiment and the photoelectric effect. In the double-slit experiment, particles are shown to exhibit wave-like behavior by creating an interference pattern when passing through two slits. The photoelectric effect, on the other hand, demonstrates the particle-like nature of matter by showing how particles, such as electrons, can be emitted from a material when exposed to light.

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