darklight03/StackMIAsub huggingface dataset:
I have noticed that when certain tube-lights are switched 'ON' , they make certain noise corresponding to their "blinking". In blinking, there are alternate periods of the tube lighting up and then going out. The "sound" is heard at the instant the tube lights up. I can not properly describe the "noise" or the "sound" I'm referring to, but it seems as if the tube-light is struck gently with something. It feels as if the gas molecules inside the tube-light are striking its inner surface. Can anybody explain this ?
In this question... Why does a photon colliding with an atomic nucleus cause pair production? ...I asked why a photon colliding with a atomic nucleus can become an electron and a positron. The answer that I thought was most illuminating explained that a photon spends some of its travel time as a particle-antiparticle pair of an electron and a positron. If it strikes the nucleus at the right time, this pair will be separated. It was explained that this is because 'Quantum Electrodynamics allows it'. Why does Quantum Electrodynamics allow a photon to exist temporarily as an electron and a positron?
In batteries, what exactly do we mean by negative and positive charges? My understanding is that the negative charge of the anode is basically an atom with an extra electron in the last orbital and a minus electron in the last orbit of the positively charged atoms in the cathode? And so the electrons keep flowing and interchanging because the atom is trying to reach a stable state. Is this correct or am I wrong? If my understanding of positively/negatively charged atoms is correct, what do we mean by saying that the electron in itself has a negative charge?
Most books on strongly correlated electrons claim that when the number of itinerant electrons is small and the screening length is large, that the system becomes "strongly correlated", (i.e. the independent electron approximation breaks down). If this is the case, why isn't doped silicon (or some other semiconductor/insulator) a strongly correlated electron system at low temperature where there are no thermal carriers? What are the critical ingredients that make a system unwilling to abide by the independent electron approximation?
I am trying to draw an activation stack. I am really bat at TikZ, so I hope you can help me out. As you can see, there are four boxes stacked one on top of the other. Each box has a name, put on the right, and is made of an upper part, where variables and numbers are displayed, and a lower part which is divided in two halves. The left half has to contain an arrow pointing to one of the boxes placed under it, the right half contains only a few characters. The box at the bottom hdoesn't have a pointy arrow, because it doesn't have to reference anything. I really hope you can help me out, I really appreciate it.
A lot of textbooks and exam boards claim that light incident at exactly the critical angle is transmitted along the media boundary (i.e. at right-angles to the normal), but this seems to violate the principle of reversibility in classical physics. How would a photon or ray travelling in the reverse direction "know" when to enter the higher refracting medium? It can't know, so I conclude that such light is simply reflected? Is this correct?
My question is regarding effect of Sun's gravity on earth. I want to know that if Sun's gravity can change Earth's landscape in long duration (i.e. billion of years) or not? Means if earth is dead planet and all other planets are not present in the solar system and Earth is as near as Sun as mercury currently orbiting. And also suppose Earth's surface is not smooth (because of hitting with other small bodies at regular interval) then can Earth's surface can be smooth in long duration by gravity of Sun or not?
Let A and E be opposite vertices of an octagon. A frog starts at vertex A. From any vertex except E it jumps to one of the two adjacent vertices. When it reaches E it stops. Let a(n) be the number of distinct paths of exactly n jumps ending at E. Find a(n) Is it right if I conclude that number of steps has to be an even number ? Also I don't know how to go further with that except I think recursion is involved. P.S. I'm having trouble solving questions in probability and combinatorics where recursions are involved like finding expected value ones. Can you provide me suggest me some links/books through which I can understand it better. Thanks
I have a question that I am just curious about. Two principles: Magnetic fields and Magnetic susceptibility Supercavitation is the use of cavitation effects to create a bubble of gas inside a liquid large enough to encompass an object traveling through the liquid, greatly reducing the skin friction drag on the object and enabling achievement of very high speeds. Can a magnetic field hold a state of supercavitation if a magnetic field could be placed inside of the bubble of the supercavitation?
Some people love creating or fostering the creation of events that are noisy, chaotic and fun, such as parties, arguments, reunions, etc. Sometimes there's a negative connotation to this (like in provoking an argument), but sometimes there is not (like in organising a big, noisy party). The word I'm looking for would be the English equivalent to the Spanish armadanzas, just in case this is helpful. Any ideas?
Earlier, I asked here whether one can have spontaneous breaking of the Lorentz symmetry and was shown a Lorentz invariant term that can drive the vacuum to not be Lorentz invariant. How relaxed are the assumptions in the CPT theorem? Can one have the theorem to be valid for a Lorentz invariant theory with a vacuum that breaks it? Can someone point me to the original and alternate proofs of this theorem? Also, is there any connection between CPT invariance and renormalizability?
Why is it said that electric current always flows from higher potential to lower potential? It's said that current flows from a positive terminal to a negative terminal, but I've read that it is actually the [negative] electrons that flow from the negative terminal to the positive one. Rather isn't it that the protons don't even move? My question here is in reference to electric circuits with batteries generally used in textbooks.
"Half of the time I was working from about eight in the morning until eight at night, and the other half I was incapacitated by excruciating pain." This is what I have currently. Is this correct or is there a better way to approach this sentence? To be specific, I am wondering about my comma usage, and whether or not more commas should be added, however, all tips are welcome. Thank you.
I learned a lot from prof Tao's notes and books because unlike many authors, he seems to prefer writing more words, explanations and intuitions rather than just mathematical formulae. His approach is also very pedagogical, and quite often, when talking about one concept, he also talks about similar concept in other fields, like group theory, differential geometry, etc. (due to his very broad areas of expertise). This makes me understand (superfically) how mathematical concepts are related to each other. I would like to know if there are some books or blogs on probability theory, stochastic processes, Monte Carlo and convex optimisation, with similar writing style and approach. Many thanks!!!
I'm new in this study and I don't know much about the foundations of mathematics, so I have a question. If I'm doing category theory, and I need to talk about "small categories" , "locally small" and etc, I need to have some set theory foundation like NBG where I can talk about this things, right? But, if I want to take the category of all categories, I will have some problem in this context with NBG as foundation?
I'm looking for a foundational book that builds up ideas like transcendental functions. For example, how the trigonometric functions are truly defined when plotted as continuous functions. I believe Shilov briefly touches on this in his "Elementary Real and Complex Analysis", but I'd like a more broad and in-depth treatment - book that, in general, deals with mostly functions (and maybe continuity/their limits). Meant for a freshman mathematics major. Books that are entirely dedicated to this topic are preferred over others wherein this topic is only treated in passing.
We all know that it uses less energy to go by wheeled transport than walking if the terrain is smooth and there are not too many hills. We also all know that when going up steep hills we get off whatever wheeled transport we are using and walk. To make things concrete, let us consider a child's scooter. How can one calculate the steepness of the hill at which point you would use more energy to scoot than to walk?
The phrasal verb "sit on sth" means "to be a member of a group of people". Well, according to Longman, "to sit in / on sth" means "to be a member of a committee, parliament, or other official group", the same thing. I don't know why my phrasal verbs book "says" just "sit on sth" and doesn't say the "in" too. Perhaps Parliament can only be used with "in" with this meaning, I don't know. When I found the meaning of "sit on sth" for the first time, I realised that I could say "To sit on a Parliament" and not "To sit in a Parliament". Is my phrasal vebs book incomplete? Can "sit on a Parliament" be correct? I hope you understand my question.
I was wondering how one would actually calculate how much oxygen would dissolve into water given the necessary initial conditions, and what those initial conditions would need to be. I assume they would be pressure, and initial concentration, but I really don't know where I would go from there. Clearly air and water have different concentrations of gases and liquids, despite having been in contact for thousands of years. And once in water, is oxygen still considered gaseous? I assume it is, but why is it called gaseous-what quality of it deems it a gas despite being surrounded by liquid?
I'm designing a space ship for a comic I'm writing. I was just finishing up the first sketch when I thought whether such a design would actually be possible. Hence my question: A spaceship is located in deep space. A propulsion system (let's make it a rocket) is attached to the side, and thus not in one line with the ship's center. Would this spaceship travel in a straight line, or rotate?
Let S be the intersection of diagonals in a cyclic quadrilateral. Let p be a circumcircle of a triangle ABS and it intersects BC in M and q is a circumcircle of a triangle ADS and q intersects CD in N. Prove that M, N and S are collinear. I tried proving that vectors NC and DC are the same, and also that vectors CM and CB are equal but nothing seemed to work. I'm probably not thinking right.
Question: Why is ionic lattice energy inversely proportional to the radius of the atom? Most heterogeneous covalent molecules are polar to some extent. The degree of polarity, or the dipole moment, depends on the difference in electronegativity difference between the two atoms. The larger the dipole moment, the higher the ionic character. What I know: Electronegativity decreases as you go downward in a group, however, the size increases, usually, as you go downwards in a group. Thus, ionic character will increase upon going downward, but the ionic lattice energy will decrease? This seems contradictory. Is this true? And if it is, why is it so?
As far as I know, a magnetic field can only be produced by a moving electric charge, or from a particle's spin (this is how a permanent magnet works, all the spins are in the same direction) What is strength and direction of the magnetic field of a stationary electron at the origin with spin oriented straight up? I suspect a function of cylindrical coordinates is most convenient.
I would like to know the status of the following problem: Given a simple graph, is there a walk traversing each vertex at least once and each edge at most once? (I am asking for a complete trail, a sort of cross-breed between Eulerian and Hamitonian walks, in a way.) In particular, is that problem known to be solvable in polynomial time, or NP-complete? Or is it suspected to belong in NPI? More generally, what is known on it? Variants: One could also ask for a circuit rather than a trail, and/or consider oriented graphs instead. Thanks in advance!
Sometimes I'll look at a word for too long and I become convinced that it's spelled or pronounced incorrectly. This happens most frequently with "spider" (I think that should be pronounced "spih-dur" [like "spitter"], not "speye-dur") and happened just now with "finger" ("fin-gur", not "feen-gur"). There's a similar variant to this (discussed here), but that's related to a word losing it's meaning. To me, the word just looks incorrectly spelled, or I convince myself that everyone's pronouncing it incorrectly. Is there a difference between what I'm describing and Semantic Satiation? If there is a difference, does this one have a name?
I'm currently studying Single-Variable Calculus independantly through MIT OCW. I can only focus on one course at a time independantly since it takes up so much time, and I really want to study Linear Algebra next instead of Multi-Variable Calculus. My question is simply this: after understanding Single-Variable Calculus, would I be able to continue into and understand Linear Algebra, or should I do Multi-Variable Calculus first?
I've just been wondering about how atoms and molecules can be quantum mechanically thought about, and I have a question. It is often said that intermolecular bonding is purely "electrostatic". I hope what this means is that it is easier to consider molecules as point charges that are attracted, but in reality, there is some sort of orbital superposition, but the small distances between different charges within a molecule don't really matter. Is it correct to say that the essential physics is captured by considering the particles as classical Coulomb charges?
Are binary systems (in case of stars and other celestial bodies) more favorable than independent existence? I've been going through an article regarding pulsars, where it was stated that 'many pulsars are found in binary systems.The companion of pulsars have been found to be normal stars, planets, white dwarf stars, neutron stars and even another pulsar. So what are the criteria to form binary systems ? I know that their sizes should be comparable, and that leads to the equilibrium of the gravitational attraction between the bodies, etc. As it is a known fact that neutron stars and pulsars are quite heavy and dense, how are they able to co-exist as binary systems with other stars, planets, etc.? Search this @ http://outreach.atnf.csiro.au/education/everyone/pulsars/
Source: gradestack.com This is a problem I am trying to solve for a long time. But still not able to proceed. After spending some time, I got a doubt whether this question is correct. Because, in a rhombus, diagonals bisects each other. Here PA=PC. That means, P is the center point of diagonal AC. So PD must be equal to PB which is not the case. Why I am wrong here? Please give pointers in how to solve this problem. thanks.
I am interested in why many small animals such as ants can lift many times their own weight, yet we don't see any large animals capable of such a feat. It has been suggested to me that this is due to physics, but I am not even sure what to search for. Could someone explain why indeed it is easy for smaller objects/lifeforms to support several times their own weight, but this is harder as objects/animals become larger?
A set of r marbles is selected from an infinite supply of red, blue, white and yellow marbles. A selection must satisfy the condition that either the number of red marbles is even and the number of blue marbles is odd, or the number of white marbles is even and the number of yellow marbles is odd. Does it mean a selection is invalid when both red is even and blue is odd as well as white is even and yellow is odd ? Do we discard this case while counting the number of selection ?
I am looking about similar triangles and I always see the word corresponding but I always forget to include it in the definition. I am trying to think of an example I can use to show the importance of the word corresponding. So here is the definition: Ex: "If the measures of the corresponding sides of two triangles are proportional then the triangles are similar." So if the word corresponding is not in the definition: "If the measures of the sides of two triangles are proportional then the triangles are similar." but what is so important about the word corresponding? Any ideas?
Most of the proofs of the Cauchy-Schwarz inequality on a pre-Hilbert space use a fact that if a quadratic polynomial with real coefficients takes positive values everywhere on the real line, then its discriminant is negative(e.g. Conway: A course in functional analysis). I think this is somewhat tricky. Moreover I often forget its proof when the pre-Hilbert space is defined over the field of complex numbers. Is there a more natural proof (hence it's easy to remember) which is based on a completely different idea?
Autorefractors are being used by eye opticians for eye diagnosis. I searched internet for articles and wiki page as well but I wasn't satisfied. I am interested to know how do they actually work. How the machine is able to focus sharp on retina automatically. How do they figure out spherical/cylindrical aberration for human eye. I even asked optician as well but he tricked out of this position saying it does all happen automatically. LOL! A detailed answer would be much appreciated. Please don't hesitate to write any technical details or mathematical derivations. I would love to know how these machines actually work. Thanks in advance!
I received an e-mail including the following sentence: I am not asking for a facetious grade change, just one that would allow me to pass. What the writer means is that the request isn't frivolous or petty. This use sounds wrong to me, but the literal dictionary definition doesn't contradict it (the dictionary definition includes, for instance "flippant"). My question is whether this is a use typical in some situation or dialect I'm not familiar with, or if it's actually completely nonstandard.
The product of nonempty sets is nonempty. I am fascinated that such a simple and seemingly intuitive statement can lead to rather astonishing results such as the Banach-Tarski paradox or the solution to this riddle. I am also intrigued by the seemingly innocent results that rely on AC (the existence of algebraic closures, any ideal is contained in a maximal ideal) and I wonder if I am missing some intuition to see how truly remarkable they are. My question: What are other examples of seemingly magical results whose proofs rely explicitly on AC, and what are examples of seemingly innocent results that rely on AC that upon further examination turn out to be fairly remarkable themselves?
Let G be a finite planar graph, then there is a natural walk around the outer (i.e. the unbounded) face of G. It might happen that a vertex v is visited more than once by this walk. Proof that this is a cut-vertex. This is a task which might be obvious at first glance, but I wasn't able to do it rigorously, i.e. by citing any of the used arguments from a book and proving everything else. I would also be satisfied with a book which I could cite. Thx.
I am looking for a good mathematical rigorous introduction to solid state physics. The style and level for this solid state physics book should be comparable to Abraham Marsdens Foundations of mechanics or Arnols mechanics book for classical mechanics or to Thirrings Physics course for quantum mechanics. Any recommendations? Edit: As a reaction to Peter Shor's comment, I try to narrow the scope of the question a bit and give some more specific subareas of solid state physics I am in particular interested in: semiconductors and applications the quantum hall effect superconductivity
Is there any way to tell how many clusters there are with respect to all the roots of a polynomial? Specifically, I'm after the multiplicity of each root but since I would like to work in floating-point arithmetic I'm afraid I have to deal with clusters. I don't mind any method of finding out: be it by numerical-iterative means during the convergence, a priori/a posteriori guess, maybe some matrix method would help..? If I have to set some small disk radius, that's ok, too.
Example: The three picked up their chopsticks and started on the food. The scene seemed strangely normal to Naomi. It was as if everything were OK, and her mom were perfectly healthy. In fact, she looked more lively and energetic than Naomi remembered. The whole illness issue seemed like a distant, bad dream. Something that belonged to another reality. Still, Naomi couldn't take the thought out of her head, so she decided to ask. If I changed still for yet, would the sentence mean the same thing?
As I've been trying to wrap my head around the principles of decoherence and quantum behavior I am left wondering why fundamental particles are 'allowed' to exhibit quantum properties even in ideal conditions ( close to absolute zero and in a 'box'). If a particle/photon behaves in a probabilistic superposition state as seen in the double slit experiment then wouldn't we expect the multiple coincidental states of the particle to interact with each other and thus cause decoherence? This would in turn lead to an innate instability of any system above a zero point energy thereby making quantum properties not identifiable at all..but indeed we do have verifiable and replicable evidence of quantum mechanics.
This will depend on whether he's suitable for the job. This will depend on whether he's suitable for the job or not. This will depend on whether or not he's suitable for the job. It is still not defined whether we're following that approach. It is still not defined whether we're following that approach or not. It is still not defined whether or not we're following that approach. "Or not" doesn't really seem to be needed to complement "whether". Why do people use it then? Is it redundancy and nothing more? Or is it for emphasis? Or are there cases when "or not" is required for the sentence to be grammatical?
Please see the sentences: I scheduled to stay after school with you today, but yesterday I was assigned a detention for today too. I scheduled to stay after school with you today, but yesterday I was assigned a detention for today also. The sentence ending in also sounds better to me, but I am not a native speaker, and I don't know it it's correct to use also at the end of a sentence. Which one is the correct form?
Wikipedia defines the notion of a pure set as follows: a hereditary set (or pure set) is a set whose elements are all hereditary sets. Why does this definition make sense? It seems to be circular. Also, wikipedia says: The inductive definition of hereditary sets presupposes that set membership is well-founded (i.e., the axiom of regularity), otherwise the recurrence may not have a unique solution. Why does the definition sometimes not have a unique solution? Is the problem the existence or the uniqueness? Can you give an example of a situation where the recursive definition from above does not have a unique solution in a setting where we don't assume regularity?
The original sentence is "The Spaniards brought horses to the Americas." I recently have made a final-term test question like this: Q: Where did the Spaniards brought horses? A: ______________________________________(Make sure to use the 'it-cleft') Not a few students answered like this: "It was the Americas that the Spaniards brought horses to." But, I think that only "to the Americas" is a right answer. Does the preposition 'to' need to be next to the noun? So, Separating 'to' and 'the Americas' seems to be awkward. What do you think about it? I'd really appreciate it if you could help me...