Mathematical Proof that Photons have No Rest Mass

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Discussion Overview

The discussion centers around a mathematical proof attempting to demonstrate that photons have a rest mass of zero. Participants engage with the mathematical derivations and the validity of the assumptions underlying the equations used, exploring the implications of these equations in the context of photon mass.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant presents a series of equations to argue that photons have a rest mass of zero, using the energy and momentum equations related to photons.
  • Another participant challenges the derivation, stating that the second line of the proof does not logically follow from the first, suggesting an error in the argument.
  • A subsequent reply acknowledges the error pointed out and proposes a new conclusion that 0 = m²c² could imply the mass of a photon is zero, contingent on the established speed of light.
  • Another participant critiques the argument as circular, asserting that the momentum equation for photons assumes masslessness without proving it, thus questioning the validity of the proof as a mathematical demonstration.
  • The same participant further clarifies their position by asking if the momentum equation is derived from the other equations, indicating a need for deeper examination of the foundational assumptions.

Areas of Agreement / Disagreement

Participants express disagreement regarding the validity of the mathematical proof presented. Some challenge the assumptions made in the derivation, while others attempt to refine the argument. No consensus is reached on the correctness of the proof or the implications regarding photon mass.

Contextual Notes

Participants highlight limitations in the proof, particularly regarding the assumptions made about the momentum of photons and the logical structure of the argument. The discussion reflects a need for clarity on the derivation of key equations and their implications.

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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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(hc/λ)^2=(pc+mc^2)^2

h^2c^2/λ^2=p^2c^2+m^2c^4

Second line does not follow from first, (right side is wrong).
 
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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)?
 
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.
 
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) ?
 

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