Wikipedia Definition and 132 Threads

In Wikipedia this sentence is written about degeneracy; In physics, two or more different quantum states are said to be degenerate if they are all at the same energy level. Statistically this means that they are all equally probable of being filled, do you agree with the bold statement?

Hi all. I have a quick question In this wikilink en.wikipedia.org/wiki/Positive-definite_matrix in the first example I don't get how they get 2x1^2 -2x1x2+2x2^2-2x2x3+2x3^2 in the third line. Can anyone bother to explain? Thanks a lot

It’s a 12 page assignment completely based on C++ simulation. I got the result and then I describe the results according to my numerical analysis while I was describing the result four of the sentences exactly match with Wikipedia. During coding in C++, I did not copy a single line from...

Hey, where can I find good quality '(not wikipedia) data on a metal material? Mainly I want as much data as possible about 11SMnPb30 + C (SS 1914). It is a leaded-cutting steel for mass production of parts where the requirements on the mechanical properties are low. Would also be nice to...

Source: http://en.wikipedia.org/wiki/Linear_equation General form:- It says (under the title General Form) "If B is nonzero, then the y-intercept, that is the y-coordinate of the point where the graph crosses the y-axis (where x is zero), is −C/B, and the slope of the line is −A/B."...

Quoting from Wikipedia: "Time dilation would make it possible for passengers in a fast-moving vehicle to travel further into the future while aging very little, in that their great speed slows down the rate of passage of on-board time. That is, the ship's clock (and according to relativity...

Wikipedia blacked out! http://en.wikipedia.org/wiki/Main_Page[SIZE="2"] I think the entire PF community might have something to say about/against this!

http://blog.wikimedia.org/2012/01/16/wikipedias-community-calls-for-anti-sopa-blackout-january-18/ Very unfortunate -- they lose a lot of standing in my own eyes. When I see things like this, one of the first things I look for is whether they are taking a reasonable position, or if they...

While gravitational redshift refers to what is seen, gravitational time dilation refers to what is deduced to be "really" happening once observational effects are taken into account. When using special relativity's relativistic Doppler relationships to calculate the change in energy and...

Obviously this could work for any topic but I thought it was interesting: http://xefer.com/wikipedia

See: http://en.wikipedia.org/wiki/Hamiltonian_mechanics I refer specifically to this passage: "Basic physical interpretation The simplest interpretation of the Hamilton equations is as follows, applying them to a one-dimensional system consisting of one particle of mass m under...

I often hear it said that the information on Wikipedia is unreliable - for example, a recent post stated that "90% of information on Wikipedia is incorrect". However, my experience has been just the opposite. I use it often for technical reference and rarely if ever find incorrect information...

In Wikipedia, it is said that \mathrm dy=\frac{\mathrm dy}{\mathrm dx}\mathrm dx. Can we divide both sides by \mathrm dx and say that the derivative is \mathrm dy divided by \mathrm dx?

For the last 48 hours I've struggled to get onto wikipedia. Every other website works fine for me except wiki, my browser just sits there loading for minutes! Sometimes it works but most of the time I get an "Oops!" message. Is this happening to anyone else? It's frustrating considering how much...

Today was my first day in astronomy. My professor, going over the general syllabus and what we'd be doing during the course, asked about good and bad sources for learning. Naturally, the responses for good materials included textbooks, science articles, etc. Bad sources were 'the internet'...

Homework Statement Hi! This is not a homework, i am just trying to understand the multinomial theorem on Wikipedia. http://en.wikipedia.org/wiki/Multinomial_theorem I don't understand how to apply this formula:- I am trying to apply this formula in this question:- (1+x+x2)5 This...

I am wondering what any experts think about these Wikipedia explanations of radioactive decay. (Wiki asks for help improving this article, so somebody must recognize some issues.) Thanks. under "EXPLANATION": Huh?? Does this mean anything?? What does "activation energy"...

I once came across a Wikipedia page describing a system where indifferent of the initial starting position, at some final time t=T the system would always reach the same equilibrium position. Does anyone know what the name of such a system is? I recall there was an animation of 4 balls each...

Hello, I was wondering if the following quote by Wikipedia (http://en.wikipedia.org/wiki/Four-velocity section "Interpretation") makes sense: Cause I would think it doesn't make sense: in this reasoning they're acting as if the norm is something like a^2+b^2+c^2+d^2, so that if...

Hi all. I was reading this Wikipedia article: http://en.wikipedia.org/wiki/Risch_algorithm I have a couple of questions about \int \frac{x}{\sqrt{x^4 + 10x^2 - 96x - 71}} \, dx and \int \frac{x}{\sqrt{x^4 + 10x^2 - 96x - 72}} \, dx discussed in the article. How the heck did they get the...

Who here writes on wikipedia? What have you written or significantly contributed to?

Hi, the wikipedia article on fermium states that it is the last element that can be synthesized by neutron bombardment but decides not to explain why. Can anybody give a layman's explanation? Thanks.

Wikipedia Isn't Exactly "100%"... http://en.wikipedia.org/wiki/Antonin_Scalia NOTE: I didn't do this, and don't worry, I'm sure Wikipedia will take care of it. Yeah, it's not in the writing as far as I can tell, but the picture is a bit off... In case it's changed, here's the one that was his...

Hello, I quote http://en.wikipedia.org/wiki/Precession from the first paragraph from the first section ("Torque-free precession"): But isn't the matrix product L = Iωs relative to the moving frame (that's how we did it in our course anyway), meaning L and omega are indeed the vectors as...

Really? I would think US users use it more... http://ca.news.yahoo.com/canadians-surf-watch-youtube-consult-wikipedia-more-other-20101228-020009-784.html" continued How do they even get their data such as age demographics ? I hope they are not data-mining.

wikipedia is full of errors

This entry on the voice "SUN" in wikipedia is correct? How can this can be possible? And if this entry is true how can be possible to create a small fusion reactor on the Earth? the entry is: The energy production per unit time (power) produced by fusion in the core varies with distance from...

Hello all. This question is not specifically about the theory itself; but the way of explaining or interpreting it. I have found few explanations about theory of simultaneity which explain in the below mentioned fashion. My doubt is that - 1.1 Light speed is same in all the reference...

http://en.wikipedia.org/wiki/Riemann-Lebesgue_lemma Have I made a mistake when it looks to me that the Wikipedia proof on Riemann-Lebesgue lemma looks like nonsense? How are you supposed to use dominated convergence theorem there?

Wikipedia shows a proof of product rule using differentials by Leibniz. I am trying to correlate it to the definition of a differential and am having no success. Differential Definition: http://eom.springer.de/D/d031810.htm

The Wikipedia article Divergence, in the section Application to The Wikipedia article Divergence, in the section [i]Application to Cartesian coordinates, says of the del-dot formula for divergence, "Although expressed in terms of coordinates, the result is invariant under orthogonal...

Every Wikipedia physics article "In need of Attention From Expert"? I've lately realized the sad situation with Wikipedia articles. Nearly every (exaggerated a bit) well-written physics article that covers some non-trivial physics has been tagged "in need of attention from an expert on the...

I am confused in a thing that is on wikipedia and need to know ur answers on this.This is from the last part of derivation for comton shift. From the RHS, you take the square of hf so it becomes h^2 f^2 + h^2f ' ^2 +2h^2ff 'cos theta now how can it take the common from the below...

What is the left transistor for? Just for the voltage drop? http://en.wikipedia.org/wiki/File:Gain-assisted_current_mirror.PNG

I know this was posted before a long time ago, but it wasn't working for a while, and now it's back. Have some fun :biggrin: example: Shortest path from invariant subspace problem to paris hilton Invariant subspace problem Functional analysis 2004 February 17 Paris Hilton 4 clicks...

Is the Osmolarity definition in wikipedia wrong? "Osmolarity is the measure of solute concentration, defined as the number of osmoles of solute per liter of solution (osmol/L). " but osmole mean particles that contribute to osmotic pressue. Meaning non permeable particles But osmolarity...

Wikipedia has been uniformly denounced as a non-reputable source for discussions on science of any kind, let alone discussions in this Earth sciences forum. Here is a nice little graph from Wikipedia showing an apparent strong correlation between global temperature and atmospheric CO2...

I think my knowledge in QM is even less than elementary. For example, right now I am reading the following article. http://en.wikipedia.org/wiki/Quantum_mechanics Here are my confusions about the text: 1. Section 'Quantum mechanics and classical physics', second paragraph: The line...

Background reading from Wikipedia I read the following from Wikipedia, Question How does a dielectric's dipole becoming polarized

The wikipedia page on photoelectric effect http://en.wikipedia.org/wiki/Photoelectric_effect talks of a 5th experimental result, which I hadn't heard before: "The direction distribution of emitted electrons peaks in the direction of polarization (the direction of the electric field) of the...

You know what I'm wondering? That's right, donuts. But seriously, can you make a wikipedia article about yourself? I was bored and decided I'd start wikipedia'ing my professors. Of course, none of them are noteworthy :smile: so i just started wikipedia'ing names I know to see if anyone...

This isn't really a homework question, can someone just explain this bit from wikipedia? consider the space X which consists of the union of the two intervals [0,1] and [2,3]. The topology on X is inherited as the subspace topology from the ordinary topology on the real line R. In X, the set...

http://www.foxnews.com/story/0,2933,519283,00.html" This is a good example of how the media has become lazy in their research for news. It also might show why those in the media that are responsible for obituaries have that position :smile:.

Everything I know about particle physics I've learned from Wikipedia articles. But since anyone can create and edit a wikipedia article, I was wondering how much faith I should put in their information.

I'm not arrogant enough to change wikipedia myself, but I suspect there is an error in a page on the speed of light. Specifically http://en.wikipedia.org/wiki/Speed_of_light#Luminiferous_aether_and_the_Michelson.E2.80.93Morley_experiment". The section states: "The null result also led...

Hello, I am new to the these forums. I recently read the article in the Wikipedia about this force (Abraham-Lorentz) and I can't understand how it can only depent on the "jerk" (that is the acceleration's derivative). Maybe i miss something, but this seems quite impossible to me: What...

http://en.wikipedia.org/wiki/Kinetic_energy#Relativistic_kinetic_energy_of_rigid_bodies" derives the kinetic energy of a rigid body at relativistic speed to be E_k = m\gamma c^2 - m c^2 The continue to say: Can anybody explain this reasoning? Just because the zero value of the kinetic...

In http://en.wikipedia.org/wiki/Frame-dragging: In http://en.wikipedia.org/wiki/Gravitomagnetism: Are those right? Surely: i] gravitomagnetism is a "magnetic equivalent", and therefore, like magnetism itself, can only affect moving objects, and so is not responsible for stationary...

does anybody besides me find the following wikipedia articles confusing? http://en.wikipedia.org/wiki/Four-acceleration a=du/dτ γu is the Lorentz factor for the speed (coordinate velocity) u In an instantaneously co-moving inertial reference frame u = 0, γu = 1 and dγu/dτ = 0, i.e. in such a...

Specifically in their mathematical topics, of course. It seems awfully good to me, but I don't know enough to be a proper judge. What's the general opinion of the people here?