Recent content by Adgorn

  1. Adgorn

    A Explicit construction of Galilean-invariant space

    I'm trying to explicitly find a projective unitary scalar representation of the Galilean group. I'll denote a generic element of the group by ##(a, {\bf b},R, {\bf v})##, corresponding respectively to time translation, space translation, rotation and boosts. In a representation with central...
  2. Adgorn

    Peskin and Schroeder problem 3.5(a): Figuring out the cancellation

    Never mind, I immediately realized upon hitting "post" that complex conjugation switches the order of Grassmann numbers. Better late then never.
  3. Adgorn

    Peskin and Schroeder problem 3.5(a): Figuring out the cancellation

    I've managed to account for all the terms except for two, which seem to have a minus sign I cannot get rid of. When expanding the variation, one of them comes from the ##\phi## variation: $$-i \partial^\mu \phi \epsilon^\dagger \sigma^2 \partial_\mu \chi^* =-i \partial^\mu \phi \partial_\mu...
  4. Adgorn

    Relativistic particle in uniform magnetic field (solution check)

    The class is using Gaussian units, sorry for not being clear on that. It looks like the examiner was wrong, I just wanted to be sure. The official answer was indeed ##\gamma T## where ##T## is the non-relativistic answer, which I could not match with my answer because I mistook ##v = \frac R...
  5. Adgorn

    Relativistic particle in uniform magnetic field (solution check)

    My solution was as follows: $$\frac {d\overrightarrow p} {dt}=q \frac {\overrightarrow v} {c}\times \overrightarrow B_0$$ The movement is in the ##[yz]## plane so ##|\overrightarrow v\times \overrightarrow B_0|=vB_0##, therefore: $$\biggr |\frac {dp} {dt}\biggr |= \frac {qvB_0} {c}.$$ On the...
  6. Adgorn

    Morin's mechanics problem 2.3 (motionless chain)

    That cleared it up. Thank you for the clear and illustrated answer!
  7. Adgorn

    Morin's mechanics problem 2.3 (motionless chain)

    In his solution, Morin solves the problem as the hint suggests: cutting the chain into small pieces, taking the component of the external forces along the curve (which is just the component of gravity here) and summing up an in integral, obtaining 0. He then claims that because the "total...
  8. Adgorn

    Calculus Looking for a rigorous multivariable calculus book

    Alright, so after boiling it down to Apostol Vol 2 vs Hubbard & Hubbard I've decided to go with the latter. Having gone through previews for both books and their table of contents it seems Hubbard will surely cover everything I'll come across in my course as well as some nice bonus material...
  9. Adgorn

    Calculus Looking for a rigorous multivariable calculus book

    I disagree with the notion that rigor somehow negates the utility of a solution manual. Any student is fundamentally limited in their ability to review their own solutions. First, even if one believes that one solved a problem in the most rigorous way possible, mistakes and misconceptions are...
  10. Adgorn

    Calculus Looking for a rigorous multivariable calculus book

    Courses in my Uni rarely have a single book that they follow, at most they feature a list of recommended books with a stern warning that the materials of the books may not overlap the course material, and the books features are usually not as comprehensive as I want them to be. The syllabus is...
  11. Adgorn

    Calculus Looking for a rigorous multivariable calculus book

    Hello everyone. I'm about to take Calc 3 next semester and am looking for a rigorous book to work with on multivariable calculus. I've gone through Spivak's "Calculus" from cover to cover and am hoping to find something with the same degree of rigor, if possible, and preferably with a solution...
  12. Adgorn

    Limit of the remainder of Taylor polynomial of composite functions

    Since $$\lim_{x \rightarrow 0} \frac {R_{n,0,f}(x)} {x^n}=0,$$ ##P_{n,0,g}(x)## contains only terms of degree ##\geq 1## and ##R_{n,0,g}## approaches ##0## as quickly as ##x^n##, I can most likely prove this using ##\epsilon - \delta## arguments, but that seems overly complicated. I also can't...
  13. Adgorn

    I Attempting to find an intuitive proof of the substitution formula

    I mean... it is, I'm just trying to prove it. The assertion that ##du = \frac {du} {dx} \cdot dx## is what drove me to try to find the proof. I can't use this equation in a formal proof because this is just notation, it doesn't mean anything on its own since standard calculus doesn't actually...
  14. Adgorn

    I Attempting to find an intuitive proof of the substitution formula

    This was actually one of the first things I tried. I took the time to prove all of these Theorems on paper and understand each stage of the proofs (and once you prove them rigorously with ##\epsilon-\delta## arguments, the intuition practically forces itself upon you). At this point I actually...
  15. Adgorn

    I Attempting to find an intuitive proof of the substitution formula

    Hello everyone. First off, I'm sorry if this post is excessively long, but after tackling this for so many hours I've decided I could use some help, and I need to show everything I did to express exactly what I wish to do. Also, to be clear, this post deals with integration by substitution. Now...
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