anuttarasammyak's latest activity
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anuttarasammyak replied to the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor?.1. We can derive the equation $$ \delta g^{\mu\nu}=-g^{\mu\alpha}g^{\nu\beta}\delta g_{\alpha\beta} $$ by indeces up down operation... -
anuttarasammyak reacted to Demystifier's post in the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor? with
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Yes, I think that's right. But the first convention is not completely arbitrary. In a sense ##g_{\mu\nu}## is more elementary than... -
anuttarasammyak replied to the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor?.Now I know that $$ (\delta g)^{\mu\nu}=g^{\mu\alpha}g^{\nu\beta}(\delta g)_{\alpha\beta} $$ $$ \delta...
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anuttarasammyak reacted to Demystifier's post in the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor? with Like.
@anuttarasammyak in general ##\delta \overline{T} \neq \overline{\delta T}##. (By the way, in LaTeX use the command \overline, not \bar...
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anuttarasammyak replied to the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor?.@PAllen @Demystifier Thanks. I went a bit easy on T .
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anuttarasammyak reacted to PAllen's post in the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor? with Like.
I don’t see why you would expect that last to be true in general. Starting from T with indexes down, in one case you have the metric...
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anuttarasammyak replied to the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor?.To put it simply $$ \bar{\delta g}=-\delta \bar{g} $$ May I understand that ##\{\delta g, \bar{\delta g}\}=\{\delta g, -\delta \bar{g}...
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anuttarasammyak reacted to Demystifier's post in the thread Graduate Is the variation of the metric ##\delta g_{\mu\nu}## a tensor? with Like.
After some thinking, I believe it's only a problem in notation. To make the explanation simpler, I find convenient to use an index-free...
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anuttarasammyak replied to the thread Just a kinematics problem from a Russian physics olympiad.
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anuttarasammyak reacted to wrobel's post in the thread Just a kinematics problem from a Russian physics olympiad with Like.
Perhaps someone would be interested in offering it to their students. There is a disk of radius ##R##. The disk is wound with two...
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anuttarasammyak replied to the thread Undergrad Matrix representation of rank-2 spinors.I have read the matrix representation in Landau and Lifshitz.
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anuttarasammyak replied to the thread High School Confusion about one of Maxwell's equations.Yes. No charge, no current.
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anuttarasammyak replied to the thread High School Confusion about one of Maxwell's equations.Yes, loop integral of electric field is generated with no regard to the wire. Free electrons in the conductor wire on the loop are...
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anuttarasammyak replied to the thread Undergrad Mixed approximation vs. full approximation for a power series expansion.We are sharing the situation. I do not find any essential difference in the drawings.
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anuttarasammyak replied to the thread Undergrad Mixed approximation vs. full approximation for a power series expansion.With no regard what function form F has, we can write $$\frac{d}{dt}[P_1(V_{10}-A_1vt)]=-\epsilon F(P_1,P_2)$$...
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