Wikipedia Definition and 137 Threads

On Wikipedia for Von Mises stress, it shows the following equation: But this does not work out. If I expand the second term I get: $$ \sigma_v^2 =...

I was just reading a thread which cited a Wikipedia article; I had thought that Wikipedia is to be considered as unreliable as the Public Broadcasting System (i.e., that has programs like NOVA, etc.), and therefore not appropriate since it is "pop science".

The English Wikipedia page seemingly changed from using "displaystyle" to "$" with the consequence that I can't use it anymore on Chrome. It is simply unreadable. Does anyone know a good browser extension to solve the problem?

Wikipedia article on proper time "Given this differential expression for ##\tau##, the proper time interval is defined as ## \Delta \tau=\int_P d \tau=\int \frac{d s}{c} . ## Here ##P## is the worldline from some initial event to some final event with the ordering of the events fixed by the...

Mentors note: This discussion about wikipedia has been spun off from a technical discussion in the High Energy subforum. Who does write those Wikipedia articles? and do they get paid for writing those articles in Wiki?

Wikipedia while deriving Bertrands theorem writes after some steps : However by a similar argument we can say that since ##β## is a constant then we can directly solve ##J^{\prime}(u)=1-\beta^{2}## and find that ##J=\left(1-β^{2}\right) u##) which is wrong. What went wrong?

Title says it all :)

In the last week Wikipedia no longer loads on Chrome. I get a security issue. I believe it is because there is an issue involving security certificates that the Chrome browser cannot get anymore from the Wikipedia site. Anyone else seeing this? I have been told Firefox only works now. Any...

Hi! I wanted to know how accurate the Wikipedia is for scientific or mathematical purposes? Is there anyone who would prefer some other sources for gaining some general information about science or math as a new learner won't be able to differentiate between what is correct or false. Thanks!

I came across this here: Is this incorrect? If we setup any coordinate system and take torques about that coordinate system, then I would have thought we say the work done in that frame is $$W = \int_{C} \vec{F} \cdot d\vec{r} = \int_{C} \vec{\tau} \cdot d\vec{\theta} \quad \left( = \int_{C}...

I was reading this article @ Medium, which shows our Neanderthal (3K or so times removed) cousin looking at Scholz's Star: And then the Wikipedia article about it https://en.wikipedia.org/wiki/Scholz's_Star which says: Prehistoric folks most certainly did NOT have access to telescopes...

There's a phenomenon over at Wikipedia. Namely, all or most (?) topics converge to "philosophy". Is there a name or some kind of coherent explanation for this phenomenon? Is it just simply the case that most branches of science originated from philosophy, and this is apparent in how Wikipedia...

Hi, I'm sorry but I'm not sure if I should post it here or in homework section. It's not homework for sure. This Wikipedia article, https://en.wikipedia.org/wiki/Kepler%27s_laws_of_planetary_motion, on Kepler's laws says the following under History section in the last para: Newton was...

Is there something that visualizes the connection between different areas of all(/almost all) phyics? It could be easily done with wikipedia articles: every article is a point in a graph and two points are connected if there's a link (one or both ways) between them. Given this, it could help to...

I have a homework to open an account in wekipedia and to write any public subject in astronomy or geology in the Arabic language Or to translate a full subject from English and of course with writing the resources Any suggestions ?? I'm new in this web site

I just wanted to get this out of my system. I'm not talking about the main article on SM but the mathematical formulation one: https://en.wikipedia.org/wiki/Standard_Model_(mathematical_formulation) Very, very hard to find good summarized material on SM out there. It's either good coverage but...

In the past, many others have asked this same question. Some teachers and professors have discouraged using Wikipedia. Articles in Wikipedia are followed by a list of books and references for further study. Except for string theory and loop quantum gravity theory, physics is less "political"...

This article in Wired describes the genesis of Everipedia an attempt to make a peer-reviewed Wikipedia where everyone has a stake in its creation: https://www.wired.com/story/everipedia-blockchain/ and here's a counter article about Everipedia mistakes fingering the wrong folks in current...

Say, we have two particles of equal and opposite charge in an isolated system in which we neglect gravity. The energy of particle 1 is: E1 = U1 + T1 Where U1 is electrostatic potential energy and T1 is the kinetic energy of particle 1. The energy of particle 2 is: E2 = U2 + T2 Where U2 is...

Hi, I just made my first Wikipedia article, about a somewhat obscure special function that is needed in radiative energy transfer problems where there is a participating medium that absorbs part of the thermal or neutron radiation (I personally need these functions in my engineering PhD...

Hello, By far, the easiest explanation of E=mc2, Einstein’s famous mass-energy equation, means that mass is a form of energy and that, mass can be turned into energy (heat, light, other particles, etc) and vice versa. It also seems easiest to say that photons are “pure energy” and are...

Homework Statement I am self studying relativity. In Wikipedia under the four-gradient section, the contravariant four-vector looks wrong from an Einstein summation notation point of view. https://en.wikipedia.org/wiki/Four-vector Homework Equations It states: E0∂0-E1∂1-E2∂2-E3∂3 = Eα∂α...

https://wikimedia.org/api/rest_v1/media/math/render/svg/a7fd3adddbdfb95797d11ef6167ecda4efe3e0b9 https://en.wikipedia.org/wiki/Lorentz_force#Lorentz_force_in_terms_of_potentials How to write this formula in terms of sums and vector components? What is ##v\cdot\nabla## ? I think it is some...

They seem to defy the most fundamental principle of SR. The first postulate/equivalence principle. According to wikipedia, we get Lorentz boost (x direction) and slightly different formulas for the inverse Lorentz boost "This "trick" of simply reversing the direction of relative velocity...

if they are really wealthy I mean... or is that against some free speech law or something

How do I find the primary source of some quote in Wikipedia that is not attributed? I mean how am i supposed to attribute something like that in a paper? paper due basically yesterday, that's why i need help quick.thanks for any help

I think it is important to keep wikipida as is , who wants it to be a place for advertisements, i for one have given a donation to keep it as is, so why not give the price of a cup of coffee,

According to Wikipedia, Cavendish was able to measure a force of 1.74E-7 N or “roughly the weight of a large grain of sand[13] of 0.13 mg” However, with my calculations using m=F/g, where g=9.81m/s/s Gives m=1.74E-7/9.81 = 1.77E-8 kg = 0.0177 mg Which is much less than 0.13 mg Am I missing...

Why does Wikipedia's page on electrical charge have a picture of a positivity charged object with arrows going to a negatively charged object? Doesn’t electrons flow from a negatively charged object to a positively charged object? Or is the picture just showing conventional current? Thanks.

"In quantum gravity, the problem of time is a conceptual conflict between general relativity and quantum mechanics. Roughly speaking, the problem of time is that there is none in general relativity. This is because in general relativity, the Hamiltonian is a constraint that must vanish. However...

If Wikipedia were a galaxy and each article a star Each section a planet leaving each word to remind us Remind us who we are. http://phys.org/news/2014-12-wikigalaxy-wikipedia-galaxy-stars.html

I always wanted to create a toolbox of critical analysis tools for young people to analyze, debate, and anticipate the near term future given our human nature and our history, especially since the scientific revolution. This is what my novel is intended to do, but writing a first (crap) edition...

The Wikipedia has a project for creating audio articles. https://en.wikipedia.org/wiki/Wikipedia:WikiProject_Spoken_Wikipedia What would be a good way to use audio in mathematical articles?

ZapperZ submitted a new PF Insights post Why You Should Not Use Wikipedia As Your Primary Source Continue reading the Original PF Insights Post.

I really like the derivations here http://en.wikipedia.org/wiki/Proofs_involving_ordinary_least_squares Could some one recommend a good book for them. I'm tired of googling these equations every time I want to use them. Thanks!

http://en.wikipedia.org/wiki/Gamma_matrices#Normalization See the image below. Which of us is right: me or Wikipedia?

Some time ago, I came across this page on Wikipedia. The problem is interesting, and I understood it. There used to be a small part on the bottom that said something like 'One can stack a block, such that it overhangs off the table, and put more blocks on the first one to make the overhang...

Physics teacher and physics professors need to come up with a better definition of nonlinearity if we expect our students to pass any basic physics course. This is because of how education has changed over the past 10 years. I hope in this thread, we collectively as members of this forum can...

I'm trying to understand the strategy being put forward by the wikipedia article on quantum pseudo-telepathy to win the Mermin-Peres magic square game. It's frustrating, because I do understand how pseudo-telepathy works, I just can't make heads or tails of the grid in the article: I get that...

Hi, I've never contributed to Wikipedia and am thinking about editing an existing article. Do I just create an account and begin changing some other guy's stuff? Not sure how that works. Suppose there is an existing section which I feel is irrelevant and I wish to delete it and add other...

Hi, I'm studying http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics#Comparison_of_interpretations but have trouble with the apparent differences of the key concepts: * deterministic - unique history * wavefunction real - hidden variables - counterfactual definiteness I...

I am looking at the formulae for the integral of csch( x ) at Wikipedia. http://en.wikipedia.org/wiki/List_of_integrals_of_hyperbolic_functions and it seems that there is a mistake, specially the solution of (presume a is 1 here for simplicity) ln | [ ( cosh( x ) - 1 ] / sinh( x ) ]...

I have a question about an entry on the following Wikipedia page - tf-idf ( term frequency–inverse document frequency). In the Matematical Details section where they are describing the inverse document frequency as follows: idf(t, D) = log \frac{|D|}{|{d \in D : t \in d}|} This is my...

I'm having a bit of a problem getting my head around Olber's paradox. The explanations haven't convinced me (I'm sure the fault is with me). According to Wikipedia: "To show this, we divide the universe into a series of concentric shells, 1 light year thick (say). Thus, a certain number of...

Here are a few topics not present in Wikipedia: the principle of special relativity the principle of general relativity constrained systems Dirac observables Thiemann's Master constraint Thomas Thiemann Group averaging Refined algebraic quantizationYou can probably think of more. I'm not...

So the wikipedia article on plutonium the author(s) claim that plutonium-239 is not as toxic as radium-226. It is my understanding that plutonium is indeed the most toxic chemical element ; and that Pu-239 is the deadliest known radiological toxin. Is this is incorrect, I'm eager to some actual...

Hi all, Recently, I was surprised to find that Wikipedia asserts that “rest mass” cannot be turned into energy via E=mc^2 (webpage link at bottom). If Wikipedia is correct, A) why don’t people conserve “rest mass” in high-energy reactions? B) How do I know when I have mass that can’t...

I think i found a mistake on wikipedia about t he moment of inertia of filled circular quadrant. the link to the page http://en.wikipedia.org/wiki/List_of_area_moments_of_inertia the link to the specific object ...

In the Wikipedia article "Quantum Gravity", it claims that there is some experimental motivation for finding a quantum theory of gravity. In one of the experiments it cites, neutrons are found to jump between discrete quantum states in the Earth's gravitational potential, similar to the discrete...

Take a trip over here and explain to me what is meant by taking the double factorial of -1. If you try to let N = 1 in the remainder formula, you wind up having to take (2(0) - 1)! = (-1)!, right? This strikes me as a typo; should it be changed? If so, to what?