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How can a grain of sand be "spaghettified" when nearing a black hole?
I have a hard time wrapping my head around this "spaghettification" process that apparently takes places when getting close to a black hole.
Gravity is proportional to the distance of the ...
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2
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Is $\frac{dE}{dt}=0$ in an accelerating particle’s instantaneous rest frame?
My special relativity book uses an argument that involves $\frac{dE}{dt}=0$ in an accelerating particles rest frame (to show a force parallel to a particles velocity is parallel in all frames).
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Lagrangian of free particle relativistic case
Why must the covariant Lagrangian of a free particle be a first-order differential?