Talk:Electron mass

Units in table

If we are talking about the rest mass of the electron, I believe the units should be reported as [m_e]=MeV/c^2 —Preceding unsigned comment added by 99.174.160.173 (talk) 18:22, 13 February 2011 (UTC)

New measurement published 2/19/14

The value in this article is 5.4857990943(23)×10⁻⁴ u; in other words the true value is expected to fall within the range of 5.4857990920×10⁻⁴ to 5.4857990966×10⁻⁴.

But the new measurement published by the Max Planck Institute for Nuclear Physics/Sven Sturm et. al. -- 5.48579909067×10⁻⁴ u -- is smaller than that lower limit.

Anyone have any thoughts on this? 75.163.218.148 (talk) 15:33, 20 February 2014 (UTC)

The uncertainties in parentheses represents the 1-sigma uncertainty, which corresponds to the value having a 68.2% chance of lying within the range you indicated. The 2014 CODATA value of 5.48579909070(16)×10⁻⁴ u lies within 2-sigma, which is not unreasonable. The true value has a 32.8% chance of lying outside 1-sigma from the mean, while lying outside of 2-sigma is much rarer (5%). Akano (talk) 19:33, 20 July 2016 (UTC)

Rest Mass vs. Invariant Mass

"Rest mass", as a concept, is emphasized in older texts. Modern texts view the mass of a particle, or s system of particles, as a Lorentz invariant quantity. The advantages are clear: Relativity is in many ways a theory of invariants, with inertial mass being the poster child for a concepts that is frame invariant. The older grouping of "gamma" with "m" and renaming this combination the "relativistic" (and non-constant) mass is not a necessity. It even leads to unnecessary confusions like "longitudinal mass" and "transverse mass". This article is the place to point that out. Qwerty123uiop (talk) 14:32, 13 December 2018 (UTC)

lest we forget F = ma

In this expression m_e is the "rest mass", or more simply just the "mass" of the electron. This quantity m_e is frame invariant and velocity independent. However, some texts group the Lorentz factor with the mass factor to define a new quantity called the relativistic mass, m_relativistic = γm_e. This quantity is evidently velocity dependent, and from it arises the notion that "mass increases with speed". This construction is optional, however, and adds little insight into the dynamics of special relativity.

This is a ridiculously untethered observation until you point out which of these masses get substituted into F = ma.

Does that equation only work in a rest frame? So you always apply it in a rest frame, and deal with everything else in a frame transform? That would be pretty weird: a law of motion that's only precisely accurate for objects that don't move.

And don't go thinking the average reader is less screwed up about this than I am. Make the reasoning here far more explicit. — MaxEnt 16:47, 23 April 2019 (UTC)

does the new definition of the kilogram change this?

" The relative uncertainty, 5×10−8 in the 2006 CODATA recommended value,[3] is due entirely to the uncertainty in the value of the Planck constant." ummm... I thought they fixed the definition of the Kilogram by fixing the value of the Planck constant. Doesn't that change this article a bit? 71.93.61.178 (talk) 01:10, 25 June 2019 (UTC)

Requested move 23 January 2022

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: moved per request. Favonian (talk) 15:50, 30 January 2022 (UTC)

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Electron rest mass → Electron mass – no need to specify Heanor (talk) 15:01, 23 January 2022 (UTC)

This is a contested technical request (permalink). Lennart97 (talk) 16:25, 23 January 2022 (UTC)

• @Heanor: This has been the title since the very beginning of the article as far as I can see, so this move is definitely not uncontroversial. Also, the article is specifically about the electron's invariant (or rest) mass, so it probably makes sense to be WP:PRECISE and specify that in the title. Lennart97 (talk) 15:20, 23 January 2022 (UTC)
  • No, it also discusses the electron's mass in special relativity, not only the electron's invariant (or rest) mass. But I'm ok to discuss this, the same as with Occitanie. --Heanor (talk) 16:01, 23 January 2022 (UTC)
    • @Heanor: RM started. It seems to me that the relativistic mass is only briefly discussed to make clear how it differs from the rest mass and is not itself part of the scope of the article. Lennart97 (talk) 16:25, 23 January 2022 (UTC)
• Support: At least at first glance, the proposed title seems more natural and WP:CONCISE for readers, and the distinction can be discussed within the article (and needs to be discussed in the article anyway). For example, the Speed of light article has an opening sentence that indicates that the article is primarily about the speed of light in a vacuum, but the article title is not Speed of light in vacuum, and that is probably desirable. —⁠ ⁠BarrelProof (talk) 19:48, 23 January 2022 (UTC)
• Support: per BarrelProof. "Electron mass" is the more natural search term. "Electron rest mass" is a better candidate to be the redirect. PianoDan (talk) 18:14, 24 January 2022 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.