Undergrad Problem when solving example with differential forms

Click For Summary
The discussion revolves around a discrepancy encountered while solving an example involving differential forms from two different PDFs. The individual found that their answer diverged by a factor of 1/2, attributed to one source including a factor of 1/p! while the other did not. They also considered whether a factor of 1/2 is necessary when analyzing the anti-symmetric part of the expression. Additionally, it was noted that the individual had overlooked summing over all components, which contributed to their incorrect result. Overall, the conversation highlights the importance of consistency in definitions and careful attention to detail in calculations.
davidge
Messages
553
Reaction score
21
Hi was reading about differential forms, when I tried to solve the example
EPOnpJe.png
given in this pdf https://www.rose-hulman.edu/~bryan/lottamath/difform.pdf. According to it, the answer is that on the image above. But when I tried to solve this same example by following the expression for ##w## given in this pdf http://www.bose.res.in/~amitabha/diffgeom/chap13.pdf, namely that a p-form ##w## can be written as $$\frac{1}{p!}w_{\mu_1 ... \mu_p}dx^{\mu_1} \wedge \ ... \ \wedge dx^{\mu_p}$$ and that ##w##, in this case, applied to two vectors ##v_{(1)}## and ##v_{(2)}## is ##w_{i j}v_{(1)}^i v_{(2)}^j##, the answer that I'm getting diverges from that given in the other pdf. What is wrong?
 
Physics news on Phys.org
I noticed that the only problem is that in one pdf they introduce a factor ##1 / p!## while in the other they don't. My answer is off by a factor of ##1/2## in this case. So what is the correct?

I guess if one were going to consider only the anti-symmetric part of ##A(u)B(v)## then a factor of ##1/2## would be needed. But if one were considering ##A(u)B(v) - A(v)B(u)## it is not clear whether a factor of ##1/2## is needed. (##A, B## are one-forms and ##v, u## are vectors)
 
You ask us what's wrong with your calculation we do not get to see?
 
haushofer said:
You ask us what's wrong with your calculation we do not get to see?
After this thread, I noticed that I have forgotten to summing over all components and that was the cause of not getting the right result.
Thanks
 
Look, if you want people to invest time to help you, you shouldn't expect them to have paranormal abilities.

I've read a couple of your questions now and they seem highly confused, giving me the impression that you're studying stuff without the right background.
 

Similar threads

  • · Replies 29 ·
Replies
29
Views
4K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
4
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K