Recent content by SiennaTheGr8

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    Announcement PF Style 2026

    Terrific. The color-contrast is great, thanks!
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    Announcement PF Style 2026

    I think there's another rule you need to target:
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    Announcement PF Style 2026

    (I haven't read through this whole thread, so apologies if someone has already given the same bit of feedback.) On a forum-page, when I'm viewing the list of threads, the thread-title/link is bolder if it's unread than if it's read. Looks like the font-weight is 700 vs. 500 here, but to my eyes...
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    High School Lorentz Transformation of Electric & Magnetic Fields Visualized

    Heaviside–Lorentz units with c=1. They're mentioned there somewhere I think, but I should make it more prominent.
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    High School Lorentz Transformation of Electric & Magnetic Fields Visualized

    I've made some more improvements to this app, including: Made the two-column desktop layout more convenient: the visualization remains "fixed" on the left (at full-screen height) as you scroll the rest of the page-contents on the right. This way you can read all the content and interact with...
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    Undergrad KE of rotating disc

    To clarify, what do you (and presumably other commenters in this thread) mean by "total" mass here? Do you mean the mass of the disc, or the sum of the masses of its constituents?
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    Graduate Rotating Disk Method to Attain Light Speed?

    I wonder... what's the speed of sound in unobtainium?
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    Graduate Rotating Disk Method to Attain Light Speed?

    Please report back with your test results!
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    Undergrad Why is the Lorentz Force always perpendicular to velocity?

    If I'm correctly understanding what you're saying, I don't think the "first-order"/"second-order" business means there's a flaw. The "order" by itself doesn't tell you whether we can notice the effects of something when only "non-relativistic" speeds are involved. Consider, for example, that...
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    Undergrad Why is the Lorentz Force always perpendicular to velocity?

    I think that would be the "proper charge density" (for the right kind of charge distribution, anyway).
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    Undergrad Why is the Lorentz Force always perpendicular to velocity?

    As an interesting(?) aside, we can "pick out" the magnetic force for a particular observer in a manifestly covariant way (I know this isn't what you meant). With the field tensor ##F^{\mu \nu}## and the "projection tensor" ##P^{\mu}_{\nu} = \delta^{\mu}_{\nu} - u^{\mu} u_{\nu} ## for observer...
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    Undergrad Why is the Lorentz Force always perpendicular to velocity?

    Notably, Zangwill uses the "Lorentz force = magnetic force" convention.
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    Undergrad Raising and lowering indices using metric tensor

    To be clear, the Kronecker delta is symmetric too.