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Activity for Mithrandir24601‭

Type On... Excerpt Status Date
Edit Post #280281 Post edited:
Added to about and rules based on https://physics.codidact.com/posts/292267/292343#answer-292343
3 months ago
Edit Post #292343 Initial revision 3 months ago
Answer A: What is the scope of this community?
It's perhaps easier for me to say or suggest what the scope excludes than what it includes - the field and surrounding areas of physics are broad and not always well-defined in themselves. In terms of what I may as well consider as 'type' of physics, in broad terms, I would generally classify a ph...
(more)
3 months ago
Edit Post #292265 Question closed 3 months ago
Edit Post #289448 Question closed about 1 year ago
Edit Post #288406 Initial revision over 1 year ago
Answer A: How are gravitational waves derived?
The typical 'most simple' derivation of the gravitational wave equation (GWE) starts by a perturbation of the 'background metric' $\bar{g}$ to get $g{\mu\nu} = \bar{g}{\mu\nu} + h{\mu\nu}$, where $h$ is the perturbation that will be described by a wave equation. 'Far away' from the source of this ...
(more)
over 1 year ago
Edit Post #285554 Initial revision almost 3 years ago
Answer A: What's the meaning of "outdated" in physics?
That sounds like something I'd say, so I'll explain this from my point of view, in particular regarding 'relativistic mass'. An 'outdated' theory or piece of terminology isn't typically mathematically 'wrong'. Rather, a given law or piece of terminology being outdated would typically mean that the...
(more)
almost 3 years ago
Comment Post #283293 I think this is fine now, as far as book suggestions/recommendations go. Strictly speaking, it should be in a different category, but as it's not a category we have (yet), I'll leave it here until we do
(more)
about 3 years ago
Edit Post #283293 Question reopened about 3 years ago
Edit Post #283293 Post edited:
about 3 years ago
Comment Post #283293 I've thought about this for a while and I've came to the conclusion that it should be closed, at least temporarily. The meta post has some support, but also points out that we need detailed info on each post. The 2 things with this question is that it really needs the books category instead of Q&A an...
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about 3 years ago
Edit Post #283293 Question closed about 3 years ago
Comment Post #283573 In general, you need some kind of reference to distinguish up from down, but lacking that, we normally say 'down' is the direction gravity pulls us. It's an arbitrary choice though, sure. If you swap up and down here, you'll just find a couple of minus sign differences, but as the direction has chang...
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over 3 years ago
Edit Post #283573 Initial revision over 3 years ago
Answer A: Find jerk of time varying force
I'm assuming that what's happening is that, for $t<t0$, there's no gravitational field, then it's mysteriously instantaneously turned on at $t=t0$. We can perform a Taylor expansion of $x$ around $t=t0$ to give \begin{equation}x = x0 + \dot{x}\left(t-t0\right) + \frac{1}{2}\ddot{x}\left(t-t0\right...
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over 3 years ago
Edit Post #283251 Post edited:
fixed Latex formatting
over 3 years ago
Edit Post #283009 Post edited:
fixed Latex formatting
over 3 years ago
Edit Post #281631 Initial revision over 3 years ago
Answer A: Is "homework-and-exercises" off-topic in Codidact?
Homework and exercises questions are generally allowed (currently anyway) under the Problems category, although there is the requirement that you need to 'show your working/attempted solution'. I don't see any issues with your two questions here (although if you want to improve them further, includin...
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over 3 years ago
Edit Post #281612 Initial revision over 3 years ago
Answer A: Interaction terms in Srednicki's proof of spin-statistics theorem
We don't need to, it just makes life easier (at least some of the time) As $\mathbf{k}$ is a 3D vector and $x$ a 4D vector, the answer doesn't appear quite as simple as 'Fourier Transforming makes them equivalent ways of doing the same thing, just in different spaces', but that essentially is the ...
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over 3 years ago
Edit Post #281283 Post edited:
Added link to Srednicki's page of textbook
over 3 years ago
Comment Post #281581 This is a great example of a question best suited to the 'Problems' category, so I've decided to move it here. If people disagree with this decision, I can move it back
(more)
over 3 years ago
Edit Post #281581 Post edited:
fixed Latex formatting
over 3 years ago
Edit Post #280987 Question closed over 3 years ago
Edit Post #280853 Question closed almost 4 years ago
Comment Post #280502 And... problems category created, wording adjustable. Meta post about specifics of textbook/paper review to follow
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almost 4 years ago
Edit Post #280719 Post edited:
almost 4 years ago
Edit Post #280736 Initial revision almost 4 years ago
Answer A: What should our policy be toward rudeness?
From my perspective, I can only agree that rudeness isn't exactly ideal. In general, if someone's being needlessly rude or aggressive etc., editing/suggesting an edit that improves the post is a good option. I'm keen to encourage good, helpful edits anyway. If, for whatever reason, you feel th...
(more)
almost 4 years ago
Comment Post #280502 People seem pretty happy with this, so I'll go ahead and add a problems category. I was thinking a paper review category would be articles. As for textbook review, this could similarly be articles, or even Wiki posts. Perhaps the textbook chapter should be talked about in another meta question...
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almost 4 years ago
Comment Post #280486 I'm afraid I don't understand how this is a physics question - it looks like e.g. a DIY or home improvement question to me. Would you be able to expand on why this is about physics?
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almost 4 years ago
Edit Post #280486 Question closed almost 4 years ago
Comment Post #280466 One category for each field of physics would be an extremely large number of categories. In the future, I could see this being useful but at the minute, tags are likely better for differentiating different topics
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almost 4 years ago
Edit Post #280466 Initial revision almost 4 years ago
Question New Category ideas
Electrical Engineering has a Papers category, for writing short articles of original work, which I for one think is a great idea. Similar to such a category would be a 'paper review' category, where people could review and explain published papers and preprints. What are people's thoughts on s...
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almost 4 years ago