Jerry Schirmer

Austin, TX

Age: 35

I am a Ph.D. general relativist working as a software engineer. I like to still go and do physics as a hobby, and to keep up my skill and knowledge.

1d
comment Can the coefficient of friction be derived from fundamentals?
Note taht the simple $F_{fr} = \mu F_{N}$ relationship you learn in intro physics isn't quite right. For instance, in that link that pentane provides, the derived $\mu$ is a function of the normal force.
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awarded Supporter
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comment Any tips on evaluating Riemann tensor?
@EdisonCesar: I would actually recommend implementing your own engine in mathematica -- it will teach you how the vector multiplication engine works, and will also teach you how to do the calculation by hand.
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comment Is current in superconductors infinite? If they have 0 resistance then I (V/R) should be infinite?
It's probably better to think of superconductors as materials where current can freely flow without an applied voltage.
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comment A couple of questions on the ADM formalism in general relativity
@Will: sorry! I described the shift when describing the lapse. Properly, the lapse function should be a function of time and of the spatial coordinates.
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revised A couple of questions on the ADM formalism in general relativity
added 397 characters in body
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comment A couple of questions on the ADM formalism in general relativity
The normal to any spacelike 3-surface is always a timelike surface.
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answered A couple of questions on the ADM formalism in general relativity
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comment Layman's explanation and understanding of Einstein's field equations
@OldCurmudgeon: in addition, consider the numerical factors fixed so that $G$ means the same thing in general relativity that it does in Newtonian theory.
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revised Spring on a rotating disc
this is manifestly a homework-style question.
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revised Spring on a rotating disc
deleted 58 characters in body; edited tags
Apr
29
answered Why is the zero of electric potential taken to be $r = \infty$, rather than $r = 0?$
Apr
25
comment Why is gravity such a unique force?
Why are bimetric theories ruled out?
Apr
25
comment Can you ever exert more downwards force than your weight?
@theonlygusti: no. Whenever you jump, you exert a downward force on the ground that is greater than your weight.
Apr
25
comment When will the pringles can fall?
Do you understand torque?
Apr
25
comment How to debunk 'The Electric Universe'?
Also, why is there a ton of plasma toward the edges of glalaxies, but none near galactic cores? Why does it seem important for globular clusters, but not for solar system dynamics?
Apr
25
comment How to debunk 'The Electric Universe'?
@Giffyguy, um, that's not what $\Lambda$CDM does. And the existing cosmological models come at the relative abundance of dark matter using various methodologies, all of which predict the same result.
Apr
25
comment How to debunk 'The Electric Universe'?
@Giffyguy: great. Point me to a calculation where the electric universe calculates the relative helium abundance correctly in the absence of dark matter.
Apr
25
comment Do résumés written in LaTeX show more promise when applying to graduate schools?
This is much more minor, but I love having a LaTeX resumé, because it lets me write a huge, annotated resumé, and then comment out the parts not relevant to the job to which I"m applying.
Apr
24
awarded Editor
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