# Mass of an Electron

**URL:** <https://boards.straightdope.com/t/mass-of-an-electron/1032569>\
**Category:** Factual Questions\
**Tags:** science-math\
**Created:** [August 26, 2026, 2:34pm UTC](https://boards.straightdope.com/t/mass-of-an-electron/1032569 "2026-08-26T14:34:42Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\
**Post date:** [August 26, 2026, 7:01pm UTC](https://boards.straightdope.com/t/mass-of-an-electron/1032569/7 "2026-08-26T19:01:58Z")

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Summary of the long answer to “Are there any particles whose invariant mass ever changes?”: The decay width thing is very real and could mean a “yes” to your question, but the center of the invariant mass distribution is fixed and thus could mean a “no” to your question. The quark mass stuff points to a need for more context when talking about individual quark invariant masses at all; that is, the first question isn’t “is the invariant mass the same” but rather “what even is mass here?”

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