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Aug
25
comment Explanation for $E~$ not falling off at $1/r^2$ for infinite line and sheet charges?
@RonMaimon now that you've had a long rest, does this answer still make sense to you honestly?
Aug
24
comment Is there a “forwards” and “backwards” in one dimension?
So a magnitude can be negative?
Aug
24
comment Is there a “forwards” and “backwards” in one dimension?
@HDE226868 sure you can. But maybe that isn't a true one dimensional space as defined by a physicist or mathematician, and a direction paramaterized by two discrete symbols +,- has been added.
Aug
24
comment Physical reason for Lorentz Transformation
You're only looking at a light-like interval; you need to show how invariance of this implies invariance of space-like and time-like intervals also.
Aug
20
comment Rotation axis of a rigid body
+1 all this work, and just one lousy up-vote?
Aug
19
comment Why should multiplication of a ket vector by a complex number change only its “direction”?
@ACuriousMind A vector multiplied by a negative real number changes its direction, yes? How are we to interpret multiplying it by a complex number?
Aug
19
comment Why should multiplication of a ket vector by a complex number change only its “direction”?
@Nathan I'm looking for an answer in the spirit of Dirac talking vaguely about vectors in an infinite dimensional space up to this point. I guess this will become clearer later on in the book, but Dirac seems to suggest this statement is obvious for physical/mathematical reasons.
Aug
19
comment When is it useful to distinguish between vectors and pseudovectors in experimental & theoretical physics?
Cool, is there a book you can recommend which goes into this in more detail?
Jul
23
comment What is a tensor?
A tensor is a geometrical object whose components transform like that of a tensor.
Jul
11
comment How does the speed of electrons change around a circuit?
The drift velocity is typically around a few centimeters/hour.
Jun
13
comment Why Lorentz Transformation in Special Relativity has to be like this?
You've thought about this before, right?
May
2
comment What transformation is the metric of general relativity invariant under?
@Siva Tullio Levi-Civita does both in his original book. I get the feeling that physicists skimmed over it, and just took out the bit defining a tensor as having components transforming in a certain way.
Apr
11
comment Invariance of Lagrange on addition of total time derivative of a function of coordiantes and time
There isn't an absolute path in Galilean mechanics, the paths ARE different in the two frames where $x' = x -Vt$
Mar
16
comment Why do both plates of a capacitor have the same charge?
user41086's point is a good one. KCL is concerned about currents at a single node, not at multiple nodes.
Feb
13
comment Does the action and Lagrangian have identical symmetries and conserved quantities?
Welcome aboard. Maybe you could click on "tags" or "unanswered" at the top to answer the difficult questions and get your rep up.
Feb
6
comment What's the interpretation of Feynman's picture proof of Noether's Theorem?
awesome question!
Aug
28
comment Discovery of $E=hf$?
@DImension10AbhimanyuPS probably after the edit was added: "The Plank law was first a fit bridging two experimental asymptotics. But it worked so well for different T and with a unique h that Plank started to "derive" this law and introduced those quanta"
Aug
28
comment If electromagnetic induction generates a potential difference in a loop, where are the “high” and “low” potentials?
What did you use to make the great diagrams?
Aug
26
comment Introduction to string theory
How many hours in total did it take you then?
Aug
26
comment Introduction to string theory
It got five stars on amazon.co.uk so I'm interested in studying from it. With its 700 pages, I guessed it would take me at least a year to read, if I spent two hours every day on it, so I was curious how long it took you.