Mathematical Proof that Photons have No Rest Mass

In summary, the conversation discusses using three equations (E=hc/λ, E2=(pc+mc2)2, and p=h/λ) to prove that photons have a rest mass of zero. The process involves setting the first two equations equal to each other and using mathematical derivations to arrive at m=0. However, it is pointed out that this is a circular argument and does not prove the initial assumption that momentum does not depend on mass. Therefore, the equations used are not a mathematical proof, but a logical consequence based on a set of assumptions.
  • #1
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Using these equations I am about to prove that photons have a rest mass of zero (mathematically)
________________________________________________________________________________________
E=hc/λ Photon Energy Equation

E2=(pc+mc2)2 Mass-Energy Equivalence with Momentum Equation

p=h/λ Momentum of a Photon Equation

________________________________________________________________________________________

Set the First 2 equations equal to each other...
E=hc/λ ------------------------------------------------> E2=(pc+mc2)2(hc/λ)2=(pc+mc2)2

h2c22=p2c2+m2c4

{h2c22}/c2={p2c2+m2c4}/c2

h22= (p2c2/c2)+(m2c4/c2)

h22=(p2)+(m2c2)

(h/λ=p+mc)2

[mc=(h/λ)-p]2

[mc(1/c)=(h/λ)(1/c)-p(1/c)]2

[m=(h/λc)-(p/c)]2

(Enter in the Momentum of a Photon Equation)

{m=(h/λc)-[(h/λ)/c]}2

[m=(h/λc)-(h/λc)]2

(m=0)2

m=0

m(photon) = 0

Is my math correct?
If so, is this legible?
And if so again, has this been proved yet and I am just completely unaware that it has?
I also made a video on YouTube about this if you want to check it out...

 
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  • #2
[itex](hc/λ)^2=(pc+mc^2)^2[/itex]

[itex]h^2c^2/λ^2=p^2c^2+m^2c^4[/itex]

Second line does not follow from first, (right side is wrong).
 
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  • #3
mathman said:
Second line does not follow from first, (right side is wrong).

Thanks. I didn't see that until you pointed it out. So I just did the math again (the right way) and it comes out to be...

0 = m2c2

Could this also prove that the the mass of a photon is zero since we already have a set velocity for the speed of light (2.99x108 m/s)?
 
  • #4
What you have done is simply proving a circular argument. For example

"p=h/λ Momentum of a Photon Equation"

is ALREADY an assumption that the momentum does NOT depend on ANY mass. In other words, you didn't show that this is true, but rather you adopt this form for the photon.

What you have done is simply doing a mathematical derivation from a known set of criteria, rather than showing that those starting criteria or description is correct. This is not a mathematical proof, but rather a logical consequence.

Zz.
 
  • #5
ZapperZ said:
What you have done is simply proving a circular argument. For example

"p=h/λ Momentum of a Photon Equation"

is ALREADY an assumption that the momentum does NOT depend on ANY mass. In other words, you didn't show that this is true, but rather you adopt this form for the photon.

What you have done is simply doing a mathematical derivation from a known set of criteria, rather than showing that those starting criteria or description is correct. This is not a mathematical proof, but rather a logical consequence.

Zz.

So in simple terms, are you saying that p=h/λ is an equation DERIVED from the other two equations (and possibly others) ?
 

1. What is the mathematical proof that photons have no rest mass?

The mathematical proof that photons have no rest mass is based on the theory of relativity and the concept of energy-momentum relation. According to this theory, the mass of an object is equal to its energy divided by the speed of light squared. Since photons have energy but no mass, their mass must be equal to zero.

2. How does this mathematical proof support the idea that photons have no rest mass?

The mathematical proof provides a logical and quantitative explanation for the concept of photons having no rest mass. It shows that the theory of relativity, which has been extensively tested and proven, supports the idea that photons have no mass.

3. Are there any other scientific evidence to support the idea that photons have no rest mass?

Yes, there are other scientific evidence that support the idea of photons having no rest mass. One of the most important evidence is the observation of the speed of light in a vacuum, which is constant regardless of the observer's frame of reference. This supports the idea that photons, being massless particles, travel at the speed of light.

4. How does the concept of photons having no rest mass affect our understanding of the universe?

The concept of photons having no rest mass has a significant impact on our understanding of the universe. It helps explain various phenomena such as the propagation of light, the behavior of electromagnetic waves, and the photoelectric effect. It also plays a crucial role in modern theories of cosmology and the study of the early universe.

5. Is it possible for new evidence to emerge that contradicts this mathematical proof?

While it is always possible for new evidence to emerge, the current mathematical proof that photons have no rest mass is widely accepted and supported by numerous experiments and observations. It would require a significant breakthrough in scientific understanding to contradict this proof and alter our understanding of photons and their properties.

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