# Einstein 1905: Is He Telling That Dm In 1/2Dmv^2 Has An Electromagnetic Nature?

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### #1 rhertz

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Posted 23 April 2019 - 09:16 PM

In the 1905 paper about mass-energy equivalence, Einstein's final equation (original german) is:

K0-K1 = L/V2 v2/2

Where V is the speed of light, L the energy of both opposite light beams, and (K0-K1) the energy change at the system composed by

both frames of reference (considering one at rest with respect to the second one moving at v speed over x axis).

In this "newtonian" formula for Kinetic Energy, the mass came from the energy of both beams of light, each one having L/2 energy.

Einstein, as far as I know, never was able either to probe this approximation to the final statement (which leads to E0=m0c2), nor he could give a satisfactory explanation between the relationship between kinetic and electromagnetic energy in the same formula.

Does it mean that he was actually satisfied thinking that mass has an electromagnetic nature, as PoincarĂ¨ thought with his cannon of light shots that had a kinetic recoil, or the true original nature of this (questionable) formula has been buried into oblivion by those who adopted his expression?

Edited by rhertz, 18 June 2019 - 08:47 PM.

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### #2 VictorMedvil

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Posted 25 April 2019 - 07:48 AM

Well, in Einstein's later work he eventually uses a description of electromagnetism and Gravity to make the Energy-Stress Tensor, So I don't think this is a measurement of the electromagnetic component of energy in the E=MC2  description is is mainly showing what is now called the Higgs Field interaction of Matter and Energy though in General Relativity he does go on to show that Electromagnetism and Gravity to effect the Curvature of the object and give the object Energy-Mass. In his earlier Works I don't think he had this idea of the Unified Field Theory he was making in mind, So No.

Edited by VictorMedvil, 25 April 2019 - 07:49 AM.

### #3 exchemist

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Posted 25 April 2019 - 02:24 PM

In the 1905 paper about mass-energy equivalence, Einstein's final equation (original german) is:

K0-K1 = L/V2 v2/2

Where V is the speed of light, L the energy of both opposite light beams, and (K0-K1) the energy change at the system composed by

both frames of reference (considering one at rest with respect to the second one moving at v speed over x axis).

In this "newtonian" formula for Kinetic Energy, the mass came from the energy of both beams of light, each one having L/2 energy.

Einstein, as far as I know, never was able either to probe this approximation to the final statement (which leads to E0=m0c2), nor he could give a satisfactory explanation between the relationship between kinetic and electromagnetic energy in the same formula.

Does it mean that he was actually satisfied thinking that mass has an electromagnetic nature, as PoincarĂ¨ thought with his cannon of light shots that had a kinetic recoil, or the true original nature of this (questionable) formula has been buried into oblivion by those who adopted his expression?

If this is so, then (as per Einstein's extension), the entire mass M of the point-like body can be decomposed into chunks of (L/V2) bits of matter until this mass M is entirely transformed into light. For this to happen, it's only needed to keep the "thought experiment" for enough time, until the mass M dissapear bit after bit while the light beam is turned on (what can take million of years?).

These two doubts (electromagnetic nature of mass and mass M consumed given enough time) arise when I analyze the original paper with utter care.

Where am I wrong? Please, refer only to the 1905 paper and not to changes that were developed since 1910 by other physicists.

Einstein's 1905 paper  in no way implies that all mass will gradually turn into light over a long enough time. What it says is that when EM radiation is emitted by a body, its mass should reduce. But it says nothing about the circumstances under which, or the mechanisms by which, that energy change can occur.

Einstein gave his result and humbly suggested it might be possible to test whether it was right by looking at radium salts. And of course the "mass defect" that is now an elementary concept in nuclear physics confirms how right he was.

It is true he worked it out only for radiative emission of energy, but the idea was soon generalised for all energy and has been observed to apply generally.