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I want to confirm if I understand something correctly. We call the "high potential terminal" the positive side (cathode). Though, electrons move from negative to positive. Logically, electrons' potential energy is decreasing so the high potential terminal should be the negative side. In my opinion, from the electrons' perspective, the high potential terminal is the negative side, but since the current flows in the opposite direction, we always talk from the current's perspective, hence why we call the high potential terminal the positive side. Is this the correct logic? | 0 |
I want to minimize the amount of unused space in a binpacking problem. I keep seeing binpacking being described as using the least amount of bins possible. Example (emphasis mine): assign each item to a bin such that number of total used bins is minimized https://www.geeksforgeeks.org/bin-packing-problem-minimize-number-of-used-bins/ Would minimizing the amount of bins guarantee the least amount of waste? And if so, is there a minimum amount of bins (based on the algorithm used, not necessarily the one from the above link) that we need to use before it is efficient? Or is binpacking "by default" efficient in minimizing waste? | 0 |
I am building a database of sorts and came across this question. I am looking for a word that includes every region that is declared and made up by humans. So no natural regions like forests or continents, but regions that are generally associated with the people residing within its borders and other human-related stuff (laws, culture, goals...). Like Estonia, Tokio, EU... I found this similar question (Generic name for places like village, town and cities). But it's only about towns, cities etc. | 0 |
In the sentence below, Greenland may not be as "green" as the name suggests. The verb "suggest" should preceed an object as it is a transitive verb, but in the sentence, there is none. In this case, should the second "as" be understood as some sort of relative pronoun though there is no noun? Or should it be understood as a comparative conjunction? If it is a comparative conjunction, is it ok to not have a direct object for "suggests"? And if something is omitted, what is it? | 0 |
What would be the best books covering topics like Algebra, Geometry (Euclidean geometry) and Calculus? Which classics can be recommended (classics in the sense of historical works that have been widely disseminated throughout the history of mathematics, for example: Euclid's Elements)? I would like to have an overview of the main classics that influenced paradigms and changes in the history of mathematics (I understand that reading can be considered difficult, but I am willing to risk it). Objective: Historical Curiosity. | 0 |
A sphere with a radius of one is put inside a cubical box with circular holes cut out such that the ball fits perfectly. The box and the sphere share the same volume; find the surface area of the box. I tried cutting the cube down the middle to get a square and a circle. I then tried to find the distance between the two points of intersection between the circle and square on one side of the square but hit a dead end. I then tried to find the volume of empty space in the box since that could help me find the volume of the protruding parts of the sphere and maybe lead to the answer but it led to no avail. | 0 |
I was watching this video. It Showed that light ( green ) changes its color to red after incidence of light. I couldn't think of how this happens because light's color is dependent on frequency rather than wavelength and only the wavelength changes when light enters a new medium , according to these answers on whether light is depended on wavelength or frequency. So what explanation can be given for the change in color in a prism. | 0 |
A student asked how to integrate tan x and he was trying while using integration by parts. I taught him the substitution method but he then asked why we can't use integration by parts. My immediate thought was it is possible just much more complicated but in trying it out, I can't seem to do so. Is it simply not possible to integrate tan x by parts? Attached are my workings for the substitution method and the failed attempt at avoiding substitution. Integration by substitution Trial of integration by parts | 0 |
I am doing some work on the topic "Adjunction" and my current interest is to give some examples. I've wanted to provide some examples connected to some basic concepts from analysis on manifolds if such exists. What I thought maybe would work is the following: Tangent space functor and cotangent space functor Tensor product functor and multilinear form functor Pushforward and pullback of differential form I am not sure if any of these are indeed adjoint functors, so if they are I would appreciate any help in proving such a thing. | 0 |
If you take an axiomatic view of Classical Mechanics and the concept mass as primitive in this context, you could derive from Newton's laws an operational way of determining masses simply by arbitrarily assigning a mass to an object and demanding momentum conservation in its interactions with other objects. But if there are interactions that increase as a function of distance, this method ceases to be practical. Does this imply that an axiomatic theory should include the prescription that forces decay with distance? | 0 |
I'm trying to connect the calculations for the determinant I'm seeing and the idea that the determinant is a signed measure of the factor by which the volume bounded by the basis vectors of a vector space changes when those basis basis vectors are acted on by a linear transformation. Does anyone have a good way of connecting this geometric intuition with the way matrix determinants are computed, specifically with the "product of pivots" method I refer to in the title to this post? Thanks. | 0 |
In a PhD thesis we have to write a preface wherein some significant theorems from the main body of the thesis are needed to be restated. The amstools or thm-restate package does not help me in this regard. In this package the restated theorem must appear after the original theorem is stated. Till date I am doing it manually. But then the problem is if I change something in the original theorem then the same change must be done in the restated theorem also but manually. Is there any efficient method to do it? | 0 |
In quantum field theory, it seems that when we consider a massive particle's spin degree of freedom, we usually do in the particle's rest frame. And I know the little group will only change spin DOF and leave the momentum unchanged. My question is: If there is a Lorentz transformation that only change the momentum of the particle and leave spin DOF unchanged? And how to determine that transformation? Or in other words, can we compare spin of particles in different momentum? I think there should have, because when we transform a particle to its rest frame, the transformation operator is not unique since we can always do a more little group transformation, so there should be a unique one to leave the spin unchanged. | 0 |
I'm trying to calculate body trajectory that launched by some impulse. I have two points: start position and finish position which can be located on different heights (points is not symmetric). I know the height that body will reach, so parabola's vertex located that height higher of first point. Vertex located between points but we don't know it's X coordinate (if points on same height it will be in the middle between them). Is it possible to find parabola's equation in this case? | 0 |
If time measured by one observer moving at a greater velocity than another observer is observed to be passing more slowly, does this imply that there's such a thing as "absolute time" or "base time" which would be the passage of time as measured by a completely static observer of the universe? Basically time as measured from the universe's inertial frame of reference. I mean given the speed with which the milky way is hurtling through space, doesn't that mean we on earth are experiencing a dramatically slowed down version of this "true time" or "base time" or whatever you would call it? | 0 |
The pressure at a point inside a static fluid is same in all directions because the the collisions of particles take place isotropically. However, at the same time pressure increases with depth. So downward pressure must not be equal to upward pressure at that point. This two statements are contradictory and I am really confused. What is the problem in my understanding of the topic? | 0 |
I am finding very hard to understand how convexity works and why a correlated strategy if a convex linear combination of Nashes is a correlated equilibrium. (Both concepts of Correlated strat. and correlated equilibrium are clear) The following is the problem I can't grasp: problem Please feel free to modify my post I haven't been posting in a while and writing LateX feels very hard, also the question isn't well posed but I am trying to solve this on my own and this post is just another attempt to find a solution Thanks to anyone helping | 0 |
tried to submit my thesis to my school. However they told me that my fonts were not embedded, which they need for archival purposes. I thought I took the necessary steps to make sure they were. I think my .pdf figures in the document are likely the culprit.... But they're telling me that it's because in adobe document viewer there are fonts that say "Embedded" instead of "Embedded Subset". They say this means the fonts are not actually embedded. Are they correct? I'm surprised how much trouble I'm finding online on if a font labeled as "Embedded" really is embedded or not. From my reading I feel like Embedded is everything Embedded Subset is and then some (the characters not used in the pdf). | 0 |
Consider the single-hole diffraction of an electron. We can make the hole as small as we like and determine the electron's position with arbitrary accuracy. When it is in the hole, we can hit it with a low-energy photon, and measure its momentum. There is no guarantee that the photon will strike the electron. But it "could". It seems that we can measure the position and momentum simultaneously if we are lucky. Does it mean UP has nothing to do with simultaneous measurements but only with statistical uncertainty? | 0 |
I know that the derivative exists when the two sided limit at one point exists and at most of the discontinuities the two sided limit doesn't exist. But at point discontinuities, the two sided limit does exist, right? So it should have a derivative, i.e. it should be differentiable. But I read some of the answers for similar past questions and they say the derivate doesn't exist. Where am i wrong? | 0 |
As I understand it, sound needs a medium to travel and more often than not, the medium is the atmosphere, however sound can also travel through solid objects. And even we can hear our own voice talking (though less loud) even if we cover our ears since sound travels through our body. So, in case we are on the moon where the atmosphere is non-existent, would we be able to hear sound (say clapping or walking) due to sound waves being propagated through our own body or is that a stretch? | 0 |
Description Hi, I'm looking for an adjective that can be used to describe someone who is skilled at easily identifying the thoughts, abilities, and perspectives of another. The first sample sentence provided effectively captures the effect that I'm trying to convey. Sample Sentences e.g. Chloe is a _____ manager, she always appoints each individual, the tasks that fit them best. e.g. Mothers are typically _____ when it comes to their children; they always know what they need. e.g. Peter is a _____ friend. I never have to worry that he won't understand me. Potential Words Words that come to mind, include "perceptive", "intuitive", and perhaps even "keen" too. | 0 |
This question is very related with software development. I would like to know if there is a word to refer the way that a word is written. For example somebody has written "HasChildren" for a variable name while the correct way should be "hasChildren". I could tell this person: "you should write hasChildren instead of HasChildren". But if I want to be more polite I would say something like "the way you use the lower and capital letters in HasChildren is incorrect, it should be hasChildren". What I want is to have a term to replace "the way you use the lower and capital letters". Does that word exist? I am not sure if capitalization would work. | 0 |
How can I start from a Hamiltonian with electron-phonon coupling and show that a kink should show up in the energy dispersion relationship? In a brief communication called "Universal Nodal Fermi Velocity" there is a graph showing a kink in data collected from Angle Resolved Photo-Emission Spectrometry. After looking around a bit I found a review that convinced me that this is due to electron-phonon coupling and am now trying to convince myself with the math. | 0 |
I do not know if this is physics or engineering, but it is complex engineering I think at least. (In the implosion fission bomb first tested at Trinity and used in Nagasaki. Not the gun type.) A big problem with the implosion design was uneven compression and a member of the British team named Tuck suggested explosive lenses (which had been employed in anti-tank weapons, I think). Somehow the lenses were supposed to even out the explosive wave but were there not multiple shaped charges in the form of the lenses? And if so, how to ensure the lenses went off at the same time anyway? Basically, I would like to understand how explosive lenses fixed the implosion problem. | 0 |
I am seeing many reels on Instagram where they ask a person "Can you spell Y, E, S". The person says "Yes". Then they ask him "Can you spell E, Y, E, S". The person says "E-Yes" instead of "Eyes". Until today I thought that they should be using "pronounce" instead of "spell". Isn't spell the opposite? You ask a person how you spell "Yes" and they would answer Y, E, S. I saw so many reels from English speaking countries and now I am terribly confused if I don't understand what spell means. | 0 |
I want to know whether alternating current will hold you to stick to the socket or throw you away and why? In my textbook it is written that alternating current is attractive in nature but when i researched a bit i found that it will contract your muscles and make you stick to the socket. So i want to know which of the fact is correct and why? Please i want a complete explanation as I am totally confused. | 0 |
The question says it all. Simply stated: Can one prove grand unification from string theory? What is the argument chain of such a proof? The textbooks I read so far only appear to give hand-waving arguments. The question is not about deducing the standard model. The question is about deducing grand unification. This means that there is a single large Lie group. Can one prove somehow that string theory produces a unique (large) Lie group? | 0 |
Are there good reasons to use, e.g., "customer relationship management solution" over "solution for customer relationship management"? I understand that in certain contexts clusters of nouns, such as in the first example, can increase ambiguity if the adjectives aren't compounded accordingly. The preposition in the latter example reduces the ambiguity by expressing the relationship the subject, the solution, and its modifiers, customer relationship management. Are there other reasons that one might want to use a prepositional phrase over stacking, and hyphenating, adjectives? | 0 |
XeLaTeX and LuaLaTeX support Unicode, and are perhaps also in some other ways better than pdfLaTeX. However, are mathematical and logical journals prepared for submissions prepared with XeLaTeX or LuaLaTeX? Perhaps it is more prudent to prepare one's work with standard pdfLaTeX? I am a bit wary about these things, as I one time when finishing an essay for a book was suddenly told that they just accepted word-submissions. What is a prudent strategy if one wants to have an essay published in a good logic journal? | 0 |
I've been investigating this problem: Given some straight line planar embedding of a simple connected graph with a simple dual graph, does there exist a straight line planar embedding of that dual graph with each vertex lying in its corresponding face in the original embedding? What if we ignore the infinite face? I believe I have found a few complicated counterexamples to the main problem, but have no clue how I would go about proving the less restrictive case or finding a counterexample. I would also appreciate smaller counterexample to the initial case. Here is a graph that I believe is a counterexample. | 0 |
I believe I have heard the expression when someone did an analogy about nuclear war, comparing the danger to a game where the opposite player's objective is not to win but to make you lose. This was apparently called, in game theory, "a scorpion player". I thought they were called the "scorpion player" but I can not find any proof or anything close to this. Have I remembered wrong ? Is it an other name ? Or have hallucinated the whole thing ? If anyone has any information on if there is a name for such player, I would be thankfull. Many thanks. | 0 |
Suppose we have a hollow conducting sphere having a charge Q residing on it's surface. Then we take another such sphere which is bigger than the one mentioned before and surround the smaller one with it, would this cause the charge on the inner sphere to appear on the outer surface of the bigger sphere? If yes, then how can a spherical capacitor even work if all the charge on the inner sphere goes to the outer sphere's outside surface I have added an image below for reference | 0 |
In Halmos'book on naive set theory, Halmos introduced the idea of a "family of sets". He explicitly defined a family to be a function from some indexing set to an indexed set. However, whenever he talks about a family, what he seems to always be refering to is actually the range of the family. I get so confused whenever he speaks of families in his text, whether he is speaking about the function or the range of the function is very ambiguous. Does "family" then formally mean the indexing function itself, or perhaps the range of the function? Thank you in advance. | 0 |
Is there an adjective/expression that conveys the meaning that this something fills a role/place that should have been filled long ago because of its high added value? For example: "The ____ exhibition on female figures in the development of modern design..." Perhaps "long-awaited" is something similar but I was hoping to find one that doesn't imply that people were expecting this change to happen. Thanks! | 0 |
Google says just that "toothless wonder" is an individual in the public who is lacking a single front tooth. Well, that's logical. But what's the purpose of word "wonder" then? If this is a slang form I can't get it, please, explain it to me. And I really want to know where it came from. All I could find out is that there were some child books named Junie B. Jones: The Toothless Wonder, although I am not sure that they were the origin. | 0 |
In linear algebra, to convert the linear transformation or operator into matrix form, it's not hard, get the standard basis of domain and substitute in the transformation and write the image of the standard basis as a linear combination of standard basis of codomain and finally get the constants (c i's) and write that in column wise in the matrix format, we will get the matrix format of the linear transformation with respect to the standard basis of the domain and codomain. My question here is why can't we arrange constants row wise? Why it is fixed to arrange constants always column wise? Thank you so much for your response | 0 |
I use latex workshop on VS code combined with okular, but I would not mind using the internal viewer. I use forward search and backward search. My question is, whether there is a way to make the editor follow the viewer and the other way round: If i scroll in the editor, that the viewer shows the according segment and also if i scroll the viewer that the editor follows? This would be very convenient. In the long run, I maybe use latex to create html or what. Is it possible to do the same with a browser as a viewer? | 0 |
I want to know what the zero electrical resistance of a superconductor means. Does it mean when we connect the terminals of a battery with a superconducting wire, the electrons move within specific tunnels inside the superconductor for which the net Coulomb's force due to the nearby nuclei and the electron clouds are zero everywhere in these tunnels? Do Cooper pairs form to justify these neutral paths? If there are such paths, are they curved or straight? Do these tunnels, if exist, make the superconductor anisotropic? | 0 |
As far as I understand it, dark energy can affect bound systems at cosmological scales (How does dark energy affect the dynamics of galaxy clusters?) effectively modifying their orbits. This phenomenon and this thesis dissertation made me wonder... Could dark energy make a bound system (like a large galaxy or a satellite galaxy orbiting a bigger one) be "less bound" so that the orbits respective to the central point of mass are larger? And if dark energy would help to make orbits be further away from the central point of mass, does it mean that dark energy could add orbital energy to bodies orbiting the center of the galaxy at the outskirts of it? | 0 |
What is the basis of the believe that there should be a unified theory which simultaneously gives quantum physics (the regime small things moving very fast) and gravity (the regime of big things moving very slowly)? Is this just wishful thinking? Are there any people who make a strong case of the possibility that no such theory can exist? This is a sincere question. Please don't throw stones at me. | 0 |
I was studying Newton's Laws of Motion and my book gives a diagram in order to explain what components together can or cannot be considered a system in the figure given below. Now it says we cannot consider D and E together as a system as they don't travel the same distance because the disc D slides over a string but I'm having a hard time getting how exactly is it sliding over the string. Is the string wound up on the disc? | 0 |
We are aware that Microsoft Word has a feature called ink Equation that allows the user to write a formula with a light pen, even if the formula is complex, and then convert it into a real equation with an acceptable font. Obviously, this is an excellent option, since it is not necessary to use multiple commands to write a lengthy equation; instead, one can simply write the equation as seen. My query is: Is there a latex editor that includes this feature? If the answer is affirmative, which editor has this capability? | 0 |
When we put a circular hole of radius R on an infinite sheet of uniformly disturbed charge we do have an electrical field on a distance z (perpendicular to the sheet) from the center of the circular hole. But if we were to pick a gaussian surface such as a cylinder of radius R there would be no flux according to the gauss theorem. Because there would be no charge in the hole. I am having a difficult time understanding what i did wrong. | 0 |
I am trying to compile the most basic file of the Kaobook template as provided here and it does not work. Now, on my TeXLive, it doesn't because it gives me in the report that it is missing an options.sty file (an issue that I do not really know how to fix). What is more peculiar is that this is not compiling on Overleaf either (and I am literally opening the file there from the option provided on the page linked above without modifying anything). Is there any specific reason? Any feedback will be most welcome! | 0 |
Background: Masters in CS/Math. I'm brushing up on statistics I see mean squared error everywhere. As a student I took it for granted, but now when I tried to find the reasons for why it's so prevalent I am told: simplicity, emphasis on outliers and mathematical properties like differentiability. So what? It's not the only function with those properties. So why is it used so widely? Are there situations where it's provably the best function to use? Are there situations where there are other functions that are provably better to use? Say I am designing my own heuristic, and I have an error I want to minimize on. How do I know that squaring the error is the best way forward? | 0 |
I understand that every function is equal to some graph, while not every graph corresponds to a function; so that sets aside the difference between functions and graphs. However, I understand that any relation can be represented with a graph, and every graph coresponds to some relation. Therefore, are the set-theoretic structures of "relations" and "graphs" exactly identical? Are they just different names of the same set? | 0 |
Once a body "crosses" the limit where dark energy wins over gravitational forces (Is there a distance from a gravitational source where the influence of gravity and dark energy are balanced out?) would there be any way to make it return to the zone where gravity overwhelms the influence from dark energy? For example, if a body is orbiting a massive point and begins to slowly recede from it due to the expansion of the universe, could some kind of slingshot effect caused by a passing external object make that body get closer to the source of gravity to the point that it gets "trapped" in the zone where gravity wins over dark energy and therefore does not recede forever? | 0 |
It seems like homotopy pullback is pullback for the case of D(CW) (derived category of CW-complexes). Is this true? In general, I want to say that homotopy pullback satisfies the universal property of pullback in a derived category. What I know for sure is that the pullback of fibrations is homotopy pullback. In a derived category such as D(CW/X), weak equivalences are isomorphisms, and each map can be replaced by a fibration. Hence, up to isomorphism, everything is a fibration, on which the homotopy pullback is the pullback. I wanted someone to confirm that this homotopy pullback (which coincides with the pullback after replacement) satisfies the universal property of pullback. | 0 |
Why not explain the apparent attraction of masses by a repulsion coming from all directions in space (perhaps the dark force)? I.e. there is no gravitational force, just a repulsive force. A point in midspace would be receiving repulsive forces equally from all directions and appear to not accelerate. Mass near the outer reaches of our universe would have more repulsive forces coming from behind, and therefore accelerate outwards. An object near a large mass would be receiving less repulsion from the direction of the large mass (because that mass has absorbed some of the force) and therefore be pushed towards the large mass. | 0 |
This question was inspired by the very first exercise in Thurston's Three Dimensional Geometry and Topology, where he gives a picture of a very tangled up loop and asks what manifold it depicts. I understand there are several knot invariants and algorithms that can be used to detect the unknot. But where are the practical implementations? Are there programs into which one can feed an actual picture of a knot (as opposed to more directly computational representations) and have it at least recognize unknots? One test would be whether it would accept the above picture as input and give the correct answer. | 0 |
I have noticed when I view a hose pouring water the color of water slightly changes when looking from above compared to when looking from the front. Also, the same thing applies when you pour water from your mouth. If you look at it from above there's a color I can't describe very good (but I think there's a yellowish in it). But when you look at yourself in a mirror pouring water from your mouth, the water is colorless. To see the phenomenon better do it immediately after you've finished brushing your teeth. Just put a little water in your mouth and pour it down (looking from above). Why do I perceive this color change? | 0 |
What is the proof for this (assuming that we draw infinite field lines). I understand why flux through some area is proportional to the number of field lines through that area only in the case of an isolated singular point charge. However, I dont understand why this would be true in other cases, like two unequal charges. To make it clear, when an area has twice the amount of field lines going through it than another area, why is the flux through it exactly twice the other area. Why not thrice or half? Also, why do field lines that originate isotropically from one charge always end isotropically at another charge. | 0 |
I want to strap down a big heavy cylinder on a flatbed truck. The strap is attached to the truck bed as shown in the picture and also behind. Will the strap slip off as in the next picture? PS. This is a purely geometrical question about the length of the strap and the shape of the cylinder. Please consider that the block cannot move sideways and is blocked in place by some metal "foot" at the bottom. | 0 |
I've read that the equatorial radius of the ergosphere of a rotating black hole is the Schwarzschild radius. But in this animation made in natural units by Yukterez it doesn't apply. I then used Yukterez equations in Geogebra and I observed the same thing. No surface scales accordingly. In the extremal case, the event horizon at the equator should be half the Schwarzschild radius, but it isn't. Is this a consecuence of using natural units? How could I "fix" this? | 0 |
An FTIR spectrum was measured for me (device from Alignment and MCT Detector) and since I'm not very familiar with FTIR I'm looking for some advice. The absorbance spectrum was obtained by measuring the reflectance of a reference sample and the actual sample. The reference sample was stainless steel and the actual sample was probably stainless steel coated with dopamine and a peptide. The spectrum shows some kind of oscillations. It was suggested that the oscillation is due to interference caused by the dopamine coating. The coating could act like a thin film. Unfortunately, I haven't found anything paper/ literature supporting the suggestion. Have you seen something similar? | 0 |
I have a question. I have a problem that when I learn science, I like to think 'how do they know this is right?'. When we learn physics or science from a textbook, we read and understand it, and then we have exam. But how do you know what is given in a textbook or said in research is correct? Because we didn't do this experiment, or we don't know what the process is to get this scientific result by ourselves? So, should I trust it and accept it? If not, what should I do? | 0 |
Suppose a body is kept in space and is not fixed about any point (i.e, not hinged). If an external force is applied, the body rotates about the centre of mass. I saw one answer pointing out that moment of inertia is minimum about the centre of mass, and thus motion around any other axis is unstable. Is this view correct? And if true, how do we go about proving that it indeed is the most stable? | 0 |
Both nematic transition and Jahn-Teller distortion distorts the lattice and reduces the symmetry of a crystal; both of the structure transition can take place at higher temperature than the magnetic transition. Why in iron-based superconductors it is called nematic transition, while in molecular system it is called Jahn-Teller effect? (Particularly in the papers talk about iron-based superconductor they never talk about Jahn-Teller effect.) Is there a deterministic experimental fact to distinguish the two? Thanks. | 0 |
I'm writing a report. In the report we refer to program participants as either dedicated or auxiliary. Each has a unique situation in which they enter the program. Since they are a particular type of participant, I have been capitalizing them to avoid confusion, but I'm not sure if this is correct. For example: When Dedicated participants submit an application they must... Is this correct? I understand it as a proper noun. I'm confused about the rule as this comes up many times in reports I need to write. | 0 |
What is the synonym/counterpart for the word "Default" in NON-IT WORLD? We use the word in computer programs/apps, meaning that there is a pre-specified/pre-defined setting or situation. The word has also different meanings in Law and Banking. But I want an alternative to use in our daily life: for instance, a physician may choose a "default" treatment for a common disease, or one can have a default position/view on a particular topic .... I want a counterpart meaning of the same word for everyday uses (non-IT world). | 0 |
Could the gravitational effects of exotic matter be replicated by using something like a torus of mass around a point? Because spacetime is relative (I'm pretty sure), for observers on the torus, or just any celestial object i guess, would they not see the other points in spacetime around them having a negative energy, and repelling objects instead of attracting them? I know I've made some sort of misconception about this, but I can't figure out what it would be, except maybe spacetime not being relative. Edit: I drew an amazing picture to demonstrate what i was thinking | 0 |
This is a snap of a textbook while describing Uniform Circular Motion. For all the diagrams, and by the vector law, the directions of the del(v) vector is perfectly fine. But I am confused why this del(v) vector will always be pointing towards the center. As it is stated here, just because v is perpendicular to r and v' is perpendicular to r', therefore del(v) is perpendicular to del(r) does not sound satisfactory. Any other logical reason why del(v) vector will point towards center only when del(t) is long enough as in diagram a and b. | 0 |
Just wanted to question how Hilbert space dimensions work. From what I've seen, they're used to generalize the mathematics of finite-dimensional Euclidean spaces into infinite-dimensional vectors. I've seen them used in quantum mechanics, and in some cases stated to "inherit finite dimensional space-time" despite the Hilbert space having infinite dimensions. So I'm basically asking how Hilbert spaces correlate to the physical spatial dimensions they represent. Are there Hilbert spaces that represent topological spaces with infinite spatial dimensions? same question for any function spaces with infinite dimensions. | 0 |
I'm not sure if this is the right community I could ask to, but I'm looking for a reference in business calculus that has challenging problems. The ones that I found so far have easy problems and can be solved within a day. I'm looking for problems that will probably take time to solve and will use a lot of thinking (and not just copy the methods/insert some formulas to solve). I would appreciate it if someone can recommend to me a reference that I'm looking for. | 0 |
I'm trying to modelise the ping pong and water cup experiment. They were already questions on stackexchange about this: Why does a ping pong ball bounce higher when it is dropped together with a cup of water? but I would try an approach with Archimede Force and superficial tension. I want to apply Newton's law on the ping pong ball, but the water and the cup are moving too and I don't know how it works in that case or how to modelise it... What do you think about it? | 0 |
I have some powder in a container with one side open. If I then compress it from that open side, does the powder evenly compress, or will the side closer to the opening (or furthest from the opening) compress more, and end up with a gradient of compression? For example, when tamping ground coffee in an espresso portafilter - is the coffee density even distributed through the portafilter, or will it be denser at the top or bottom? And what factors (if any) affect this? Regarding individual particles - shape? size? texture? uniformity? compressibility (of each particle)? | 0 |
I recently delved into the topic about the reality of the Dirac string. Although several authors show how this object should not be real, this article "Field momentum and the reality of the Dirac String" proves they're wrong. I think the thesis of the article is very strong and I would like your opinion. I am writing my bachelor thesis on this study, I am learning both the Lagrangian and Hamiltonian formulation of the system to understand if I can find a solution, however the authors of the article seem to me to use only classical arguments. Any ideas? | 0 |
I read about the 'Method of undetermined' in the wikipedia and it said as following: In order to find the particular integral, we need to 'guess' its form, with some coefficients left as variables to be solved for. This takes the form of the first derivative of the complementary function. Below is a table of some typical functions and the solution to guess for them. I can't understand the sentence "This takes the form of the first derivative of the complementary function" what does it mean? Is there any relation between particular integral's form and derivative of the complementary function? | 0 |
I see the statement that: Similar to how a car needs fuel to run, a computer needs electricity to power it. In this case, I comprehend its meaning. However, I don't really get why "similar" is used at the top of the sentence here. If "similar to how" is an adveribial clause, my searches don't find any results or any envidence. Likewise, I can't figure out clearly any type of reduced relative clause. | 0 |
I have read that if helicopter's engine fails, you set the pitch to minimum but not reverse pitch. The rotor would have to be tilted back to provide an angle of attack on the blades so it glides like a fixed wing aircraft but with the rotor spinning to keep the blades from buckling under the weight of the craft. I think it would have to go into a slight reverse pitch to spin the same way. That would also provide more angle of attack on the receding blades where it is needed because of the lower air speed over those blades. How does it keep rotating in the same direction with the air going up through it if it can't go into a slight reverse pitch? | 0 |
I know that we have to use 'the' when it comes to groups of people, for example: The French are good at cooking. When nouns and adjectives are the same, we can omit 'the' Americans are good at sport. However, I do not know what to do with a word "Brit". I'd like to know Brits more OR I'd like to know THE Brits more? Can I omit the definite article? | 0 |
In an electric circuit, electron flows from the negative terminal of a voltage source to the positive terminal, which in turn, gives us the the conventional direction of electric current. So, the first question that arise in my mind is: On moving to the positive terminal, does the electron gain stability? If it does, then we know that an electron moves from a higher energy level to a lower energy level it releases a photon of a frequency dependent upon the energy gap, to gain stability. The second question is: Why does an electron move towards a region of lower energy but in a circuit, towards higher energy (positive potential is obviously a higher energy level) | 0 |
Suppose I have a rhombus based penrose tiling like the following: Is there some coordinate system that allows me to easily uniquely refer to a specific tile, and also from the coordinates efficiently calculate the coordinates of the tiles that border it? I also need to be able to easily tell what tile is on the "opposite side" edge of a tile with respect to a different tile that also borders it. Basically my end goal is, if I have some instruction like "Straight, Straight, Left, Straight, Right" and follow them on the grid to calculate if I ever cross my own path and when. | 0 |
I am attempting to apply the Grubler formula (which can be found here: https://learnmech.com/how-to-calculate-degree-of-freedom-of/) to determine the number of degree of freedom, but it does not seem to yield the expected in some cases. Is it correct that there are some cases where the Grubler formula should be avoided? If yes, how can I recognize these cases and what method could I use instead? EDIT: I've edited it to only ask about the underlying concept as required. Now, one might say that it lacks an example where it doesn't work ... tell me if that is the case, I'm just trying to comply. | 0 |
Interference is explained by showing a diagram of two parallel waves of light that are in phase or out of phase and showing the result of the fields constructively or destructively interfering. Implicitly it seems to be the case that they are polarised in the same plane as well. What I wanted to know is what this picture looks like when we're talking about unpolarised light. I'm reading about XRD and Bragg's, and can't seem to find any indication that polarised X-rays are used. And if that isn't the case, then even if two waves are in phase, the net E fields are polarised in random directions to each other and wouldn't undergo constructive interference. Where am I going wrong here? | 0 |
The wavelength or frequency of light determines its color. Photons seen as particles are said to have a frequency, determined by its energy, so I assume that 'is' the same color. But being quantum particles, photons also have a probability wave, determining how likely it is to detect it in a certain state (like, a position). How do these waves relate to each other, if at all ? Iow, would the double slit experiment have a different result when performed with 'red photons' instead of 'green photons', and if so, how would it differ ? Sorry if I get things wrong, I'm just grappling with the nature of these things. | 0 |
How strong of a gravitational field do you need for a projectile to make a full loop? By full loop I mean it curves once around the by dot, and then it ends up on the same trajectory as it was one before it approached. How many times the Schwarzwald radius would the projectile have to get for this to be possible? I know the limit in Newtonian gravity is half a loop. | 0 |
I had the feeling that physics has moved on from the idea that spacially bounded objects located in spacetime (such as particles) can be fundamental. Instead, QFT describes everything by quantum fields which are better considered as an everywhere present property of spacetime rather than embedded in it. From this perspective, it always felt to me like string theory is a step back, talking again about bounded objects located in spacetime (i.e. "free floating strings", as this answer states). Question: Is there a flaw in my understanding? How can free floating bounded strings give rise to spacially extended quantum fields? I am a mathematician and fine with advanced mathematics, but am a layperson when it comes to physics (you might consider me as an undergrad in this respect). | 0 |
I want to know the mean first passage time (MFPT) on a unit interval for two boundary conditions (please see attached figures a and b for your reference). This is in the context of the hydrodynamic dispersion of a particle. In case a) the b.c switch from reflection to absorbing whereas in case b) the b.c is reflective. Can anyone help me to figure out the mean first passage time in this problem? | 0 |
I am currently looking for a cyrillic font (for russian typewritting). It must be an opentype font usable with lualatex and fontspec, and must be complete : roman, italic, bold, small caps, superiors letters and figures, in serif and sans serif. For all I know, Libertinus is very close, but it lacks cyrillic small caps and superior cyrillic letters. Does a more complete font exist? | 0 |
I have a knot about the "secondary" colours and its spectra. So If I look the spectra of white light, I can see that yellow, which is between R and G, has some wavelength. If I do an addition of light of Red and Green, I get yellow. Ok. Now If I do an addition of light of Red and Blue, I get Magenta. But how come that Magenta is only a perception and has no wavelength, as Yellow for example ? I understand that some colours physically do not exist, but I dont understand why yellow exists as a real physical wavelength but not magenta. Can someone help please | 0 |
According to Stephen Boyd's textbook on ADMM, the global variable consensus ADMM updates are given as the following, which is pretty straightforward to understand: However, I've recently seen another variation of the consensus-ADMM updates from this work I tried very hard to derive the primal updates shown above but I just cannot arrive at the same equation. I wonder if this is the same as global variable consensus ADMM at all? | 0 |
So, I'm trying to make a basic shooter game in desmos, and I have a list of points that act as bullets. The (current) enemies right now are only some triangular jets that fly in a linear manner. My current goal is: Make it so when the point hits the triangle, it deletes itself from the list, and thus itself from the screen as well. The Triangle, upon getting hit, moves downwards in a curved path and stops when it hits the ground (a line). https://www.desmos.com/calculator/sjezpkhhxl Here is the graph itself. The lines for the bullets themselves are in the folder titled bullet and the lines for the triangle are labelled as enemy: fighter jets. If any more details are needed, please do let me know. | 0 |
My wife mentioned today that she would love to know more about 'how the world is made up'. She stopped learning science at a young age and finds most stuff meaningless or incomprehensible. She is not a child - so the challenge is, how to introduce the history and development of atomic physics with minimal specialist vocabulary, in a manner that reliably explains how physics got to the standard model. Pictures are good, waffle is bad, mathematics and equations is a no, hand-waving or similar patronising (eg '...for idiots!') statements are a no. Her wish is aspirational - so the presentation needs to be reasonably effortless... Any thoughts or suggestions? | 0 |
I remembered this really corny phrase today when I was on a walk but I forgot later before I could write it down. It's kind of like "You are what you eat" but with different words. It's not: You reap what you sow. You're the sum of your actions. Easier said than done. (It is a different one but they're both about contiguity. I don't remember what it is.) | 0 |
Why does she try and pull the stunt? This is probably an elliptic sentence - Why does she try the stunt and why does she pull the stunt (off)? - but it still seems like very bad style to me. Why does she (even) try to pull the stunt (off)? I am aware that it is not clear that the attempt was successful, however the to-infinitive comes much more naturally to me, for whatever reason. From context, it is clear that it was successful. So, would you consider it weak style to use an ellipse like this? | 0 |
I am trying to determine a statistical test to run. My dependent variables is employee retention. The independent variables are exam score and interview score. Unfortunately because employees who failed the the exam did not moved onto the interview, I do not have interview scores for all cases. Do I run a logistic regression? Is there any other test I can run to be able to use exam and interview scores to predict employee retention? | 0 |
To my understanding, the curvature of spacetime is determined by the stress-energy tensor. I was wondering if we could calculate some of those components using radiation. Is it possible that objects that possess immense electromagnetic radiation, for example, will follow with a strong gravitational pull? Does radiation occupy physical space? Just had a thought experiment where I visualize spacetime like water that engulfs any solid object and doesn't go through it. But in my visualization, the actual spacetime didn't touch the solid object since the solid object occupies more space than its physicality. It engulfs the radiation and interacts with it. Just thoughts :). | 0 |
So in my course of quantum computation i came across this question that "What guarantees a quantum gate to be unitary?" i was specially curious about photonic quantum gate. At first i thought that maybe unitary is not something that is guaranteed by any special phenomena but its inherited by the math behind quantum physics and that we use to describe any physical operation with an unitary operator but is it really the answer? | 0 |
We need to solve this problem without using trigonometry. KLMN square is inside ABCD square. Prove that midpoints of the segments AK, BL, CM, and DN are vertices of a square. KLMN can be situated anywhere inside ABCD. I think that we are going to use congruent triangles. I tried to draw so that the intersection point of diagonals of ABCD and KLMN coincide, I also tried the opposite to consider the general case, because KLMN can take an arbitrary position. So, I would like to see approaches, how to prove. | 0 |
I wonder if above some energies (or diagram level?) the virtual particles would rather behave (or become) like a micro black hole. Does that make sense? Could this somehow introduce a cut off above which Feynman diagrams would be unnecessary (the micro black holes would always evaporate in perhaps a few different ways), and in doing so avoid renormalization? This are speculations from a freshman, so please don't be hard on me. | 0 |
An oxymoron is a figure of speech in which contradictory terms appear in conjunction with one another. Can there be a figure of speech in which similar compatible terms appear in conjunction with one another? For example, how would I describe the following sentence? Nice should be great. Nice being the location, but also a compliment. Play on words? Comedic effect? Feel like there isn't one and idiom or a proverb doesn't quite fit. | 0 |
As my title says, is a "change in scenery" as correct as a "change of scenery"? I am self-conscious of how a "change in" might sound odd or off or be even absolutely incorrect. Are both forms of this sort of expression truly correct? I know the latter one is (a "change of scenery" makes full sense), but what about the former version of this idea with "in" as its preposition instead of "of"? | 0 |
So there's this debate ongoing on one post that this phrase is incorrect. People are getting confused and wondering how can Adele take a divorce from her own son. The sentence is: Adele says new album will explain her divorce to her young son. Is the above sentence correct? I always thought a divorce was taken from someone and not to someone. For context, the sentence is being used a headline caption for an image. | 0 |
If all bodies emit thermal radiation, does it mean that it's impossible to build something that can retain all of its energy - and last indefinitely? i.e. is everything in our world, including a dynamic, living system that can self-repair, eventually gonna collapse? OR - there is something in Thermodynamics similar to Superconductivity in Electromagnetism that would help prevent this? OR if there is no such effect, is there, even theoretically, a way to mitigate the effects? I can only think of creating new energy within a system faster than the system can lose it due to thermal radiation, but doesn't this violate conservation law(s)? | 0 |
I'm looking at an example system which has a very large number of microstates (effectively infinite - not possible to enumerate exhaustively, but possible to sample from). The energies of the microstates however are drawn from a normal distribution with some average energy and standard deviation of the energy. What is the partition function for a system like this expressed in terms of the average energy and standard deviation of the energy? What is the entropy? | 0 |
If the vacuum energy of the universe is not at its minimum, that is, the universe is at a false/metastable vacuum state, then it could decay into the true vacuum state. However, if our universe is already at the true vacuum state, then, this decay would not take place. However, in the far future, if we would wait enough time, could the true vacuum transition into a false vacuum level somehow? Or is this utterly impossible? | 0 |
I was thinking of converting a disused chimney into a static periscope, using long focal length lenses at top end of the chimney. A static design would be easier, so I was wondering how one would design the mirror shape such that it converted a cylindrical view onto the lens, which could then be processed at the other end of the chimney to generate a cylindrical view once more. Is it even possible? | 0 |
Assuming right to be positive, in this question, is the work done by the boy positive or negative? I would think it is negative because the force that the boy exerts is towards the left while the movement of the boy is towards the right. I would think that work done ON the boy is postive because the force that the string exerts on the boat is towards the right which is the same direction as the motion of the boy. Am I correct? I don't quite understand how to think about the idea of work done BY the boy in this context. What does it mean for work done BY the boy to be negative? | 0 |
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