Photon Rest Mass: How We Know & Mass While Moving

In summary: No, you are wrongly simplifying a general equation to a very special case.p = \hbar k where k is the wave vector (\frac{2\pi}/\lambda) is used pretty much everywhere in QM, including massive particles such as electrons. Note that momentum is conserved, but not velocity, so momentum is a much more fundamental property than velocity.In the non-relativistic limit for massive particles you get E = \frac{1}{2m}p^2.For a photon, the non-relativisitc limit obviously does not make any sense. The most reasonable thing you can do is (as jtbell pointed out) use E^2 = (m_0 c^2
  • #36
aleemudasir said:
How did we come to the conclusion photon has no rest mass? Does photon have any mass(not talking about rest mass) while moving at usual c?
=ozie: Michelson and Moreley's experiment proved that no matter how a mobile point with a speed v is directed to the light source or run away from it, the speed of light is always the same! But the experiment (as the later experiments did) was based on the interfence between an direct light beam and reflected one. In my opinion this experiment has a limit because too small shift of interferences it is possible to escape to power resolution of the device. Some books presented the ideea of an estimated rest mass of photon of 10 to minus 47 kg ( 10-47kg). So we can conclude that the speed of let say 299000 km/s to be not sufficent to have a relativistic mass infinite! To such value it is posible that the shift of interference to be unobservable, the shift to be under the threshold of resoluition of device!
 
<h2> What is photon rest mass?</h2><p>Photon rest mass refers to the theoretical mass that a photon would have if it were at rest. However, according to the theory of relativity, photons cannot be at rest and therefore do not have a rest mass.</p><h2> How do we know that photons do not have rest mass?</h2><p>Scientists have conducted numerous experiments and observations that have consistently shown that photons do not have rest mass. Additionally, the theory of relativity, which has been extensively tested and confirmed, also predicts that photons do not have rest mass.</p><h2> Can photons have mass while moving?</h2><p>No, according to the theory of relativity, photons cannot have mass while moving. This is because as an object approaches the speed of light, its mass increases infinitely. Since photons travel at the speed of light, they would have infinite mass, which is not possible.</p><h2> How do we measure the mass of a moving photon?</h2><p>Since photons do not have rest mass, they cannot be measured in the same way as other particles. However, their energy can be measured using various methods, such as the photoelectric effect or Compton scattering. This energy can then be used to calculate the equivalent mass of the photon using Einstein's famous equation, E=mc^2.</p><h2> Is the concept of photon rest mass still debated?</h2><p>No, the concept of photon rest mass is well-established in the scientific community and is not currently a topic of debate. However, scientists continue to study and explore the properties of photons, including their behavior and interactions with matter.</p>

FAQ: Photon Rest Mass: How We Know & Mass While Moving

What is photon rest mass?

Photon rest mass refers to the theoretical mass that a photon would have if it were at rest. However, according to the theory of relativity, photons cannot be at rest and therefore do not have a rest mass.

How do we know that photons do not have rest mass?

Scientists have conducted numerous experiments and observations that have consistently shown that photons do not have rest mass. Additionally, the theory of relativity, which has been extensively tested and confirmed, also predicts that photons do not have rest mass.

Can photons have mass while moving?

No, according to the theory of relativity, photons cannot have mass while moving. This is because as an object approaches the speed of light, its mass increases infinitely. Since photons travel at the speed of light, they would have infinite mass, which is not possible.

How do we measure the mass of a moving photon?

Since photons do not have rest mass, they cannot be measured in the same way as other particles. However, their energy can be measured using various methods, such as the photoelectric effect or Compton scattering. This energy can then be used to calculate the equivalent mass of the photon using Einstein's famous equation, E=mc^2.

Is the concept of photon rest mass still debated?

No, the concept of photon rest mass is well-established in the scientific community and is not currently a topic of debate. However, scientists continue to study and explore the properties of photons, including their behavior and interactions with matter.

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