What is General: Definition and 1000 Discussions

A general officer is an officer of high rank in the armies, and in some nations' air forces, space forces, or marines.In some usages the term "general officer" refers to a rank above colonel.The term general is used in two ways: as the generic title for all grades of general officer and as a specific rank.
It originates in the 16th century, as a shortening of captain general, which rank was taken from Middle French capitaine général.
The adjective general had been affixed to officer designations since the late medieval period to indicate relative superiority or an extended jurisdiction.
Today, the title of general is known in some countries as a four-star rank. However, different countries use different systems of stars or other insignia for senior ranks. It has a NATO rank scale code of OF-9 and is the highest rank currently in use in a number of armies, air forces, and marine organizations.

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  1. karush

    MHB 3.2.5.3 General Solution if system

    $\tiny{307w.3.2.5.3}$ https://mathhelpboards.com/{http%3A//faculty.sfasu.edu/judsontw/ode/html-snapshot/linear02.html Find the general solution of each of the linear system \begin{align*} x' & = -3 x + 4y\\ y' & = 3x - 2y \end{align*} $A=\begin{pmatrix}-3&4\\ 3&-2\end{pmatrix}...
  2. Lilian Sa

    Star collapse in general relativity — pressure as a function of star radius

    What I've done is using the TOV equations and I what I found at the end is: ##e^{[\frac{-8}{3}\pi G\rho]r^2+[\frac{16}{9}(G\pi\rho)^{2}]r^4}-\rho=P(r)## so I am sure that this is not right, if someone can help me knowing it I really apricate it :)
  3. Demystifier

    A Infinities in QFT (and physics in general)

    Moderator's Note: Thread spun off from previous thread due to topic change. I see. Basically you are worried by stuff a mathematical physicist would study with fancy schmancy functional analysis. I'm not worried too much by such stuff because I don't think that actual infinities (actually...
  4. J

    Waves - General question about Damping and how it affects a propagating wave

    I think increasing the damping would decrease the amplitude and increase the Period (T). But, what I'm really unsure about is the frequency, wavelength and wave speed. Would it be no effect on those three? Because if dampening acts like friction, wouldn't it slow down the wave/ increase speed?
  5. J

    I Parallel transport general relativity

    Suppose you have a tensor quantity called "B" referenced in a certain locally inertial frame (with four Minkowski components for instance). As far as I know, a parallel transportation of this quantity from a certain point "p" to another point "q" consists in expressing it in terms of the...
  6. A

    I Light Deflection Formula: Impact Parameter & Angle Shift

    I know the basics of GR, but I'm far from an expert. I'm interested in the general formula for the angle shift experienced by a light ray in presence of a gravitational field. Light bending is topic covered in many books, of course, however the usual treatments would just not do for my purposes...
  7. J

    General work of friction question

    if the Work done by friction is -4.73 for object #1 but the work done by friction for object #2 is -4.63, in which scenario is the Work greater - the signs are throwing me off. Also, let's say the initial elastic energy of a ball is 5 and its final energy is 0.27 (scenario #1) vs its final...
  8. atyy

    I GR: Attractors & Liouville's Theorem

    In classical Hamiltonian mechanics, because of Liouville's theorem about the volume of phase space being preserved by time evolution, there are no attractors. Naively, I think of the Raychaudhuri equation in GR as showing a shrinking volume. However, I guess Raychaudhri's equation does not...
  9. H

    B Explaining Perihelion Shift of Mercury in GR Theory

    Recently, when reading an entry about Mercury's perihelion shift, someone mentioned a "hand-wavy" explanation as to why GR predicts the orbit so precisely. I was wondering if there was some elementary way to expound on what he was saying. Fundamentally, the comment said something to the effect...
  10. DavidGarcia

    Gauss Law general physics 2 question

  11. R

    Any past physics olympians here?

    I really would like to know the process of your preparation... Like how and when you started preparing, what growth you saw in your problem solving capacity and so on. Kindly share about the beautiful journey. If possible, give me some tips/resources as I'm also an aspiring olympian.
  12. PainterGuy

    Finding the general solution of this nonhomogeneous linear system

    Hi, I was trying to do the following problem. My attempt. Finding the reduced row echelon form for the system above. I do not see any way to proceed any further. The following is the solution presented in solution manual. How do I proceed to get the following answer?
  13. brotherbobby

    I General Relativity: Exploring Space & Time

    (1) I remember reading somewhere that in general relativity, "space" and "time" lose their metrical meanings. Is that true? And yet, we continue talking of space and time in general relativity as spacetime. (2) Moreover, as someone mentioned in this thread, what happens to the speed of light? In...
  14. R

    I General Magnetic Dipole Moment For an Electron in an Atom

    On the first attached page ##\mu_z## is associated with orbital angular momentum (Eq. 41.34). On the following pages (Eq. 41.38) it is associated with spin angular momentum? Are these both part of the same thing? I tried to read further but the book does not address this. In example 41.6 it...
  15. phoenix-anna

    I Correcting General Relativity Effect on Atomic Time

    The International Bureau of Weights and Measures combines the readings of 450 atomic clocks around the world to obtain a time standard with sub-nanosecond accuracy. These clocks run at different rates - a clock at 1 km of altitude gains about 7 ns a day compared to one at sea level due to the...
  16. manolo-mm

    I General Relativity: Angular Momentum, Gravity & Questions

    Hi everybody I saw quite a nice Youtube vid about general relativity and how gravity bends spacetime and therefor redirects angular momentum into the center of gravity. I thought the first time I begun to understand the concept but immediatly the questions poped up. The video basically says...
  17. E

    B Understanding the Stress-Energy Tensor & Solar Mass in General Relativity

    In the test of General Relativity by perihelion motion of mercury, the stress-energy tensor is set to 0 in Schwarzschild solution. Then, is the curvature caused by solar mass, or by the 0 stress-energy? Or, do we consider solar mass as the gravitating mass? Or the 0 stress-energy the gravitating...
  18. A

    I General worked out solution for diagonalizing a 4x4 Hermitian matrix

    Hello, I am looking for a worked out solution to diagonalize a general 4x4 Hermitian matrix. Is there any book or course where the calculation is performed? If not, does this exist for the particular case of a traceless matrix? Thank you!
  19. I

    B Is this explanation of gravity under General Relativity legit?

    This video explains gravity in a way I haven't encountered before (regardless of how irritating the presenter may be). Nevertheless, I find it hard to believe that a squirrel falls from a tree to the ground due to gravitational time dilation between its head and its feet. The amount is so...
  20. LCSphysicist

    I General relativity, Electromagnetism and Feynman Diagrams

    We are discussing the introduction to Einstein field equation, so he start talk about the linearity in Newtonian gravity and the non linearity in GR. But there is somethings I am missing: > " (...) in GR the gravitational field couples to itself (...) A nice way to think about this is provided...
  21. U

    Derivation of torque on general current distribution

    How do I simplify the expression...
  22. E

    Lie derivative of general differential form

    The first two parts I think were fine, I expressed the tensors in coordinate basis and wrote for the first part$$ \begin{align*} \mathcal{L}_X \omega = \mathcal{L}_X(\omega_{\nu} dx^{\nu} ) &= (\mathcal{L}_X \omega_{\nu}) dx^{\nu} + \omega_{\nu} (\mathcal{L}_X dx^{\nu}) \\ &= X^{\sigma}...
  23. F

    I What tests can falsify general relativity?

    I know that general relativity fails in singularities like the center of a black hole or the big bang. GR also fails at fundamental particle levels like electrons, protons and neutrons etc. I.e. GR cannot explain interactions of various fundamental particles?? (Am I correct?) But these does...
  24. D

    I Exploring Matter in General Relativity: Understanding the Lagrangian

    I was going over the Einstein-Hilbert action derivation of the Einstein field equations and came across a term that does not seem to be explicitly defined. That term is the Langragian for the matter fields. What exactly is matter in General relativity in the context of the Lagrangian? Here is...
  25. J

    I General Relativistic Quantum Theory?

    Is it possible to have some kind of General Relativistic Quantum Theory without passing through the stage of Quantum Field Theory (where Quantum Theory is married to Special Relativity)? Einstein attached primary significance to the concept of general covariance as shown in this letter in 1954...
  26. T

    General Query on Archimedes' Principle

    I had some questions about Archimedes' Principle. This image shows an object being gradually submerged into fluid: As far as I'm aware, when the object is floating, weight of fluid displaced by object = upthrust acting upwards on the object. When the object is fully submerged, volume of the...
  27. Qwet

    I Conservation of energy in general relativity

    Hello. I have a question about the law of energy conservation in GR. As time is inhmogeneous, we don't have energy-momentum 4-vector which would be preserved during system's dynamical change. It is only possible to define 4-vector locally. And next, the problem regarding how to sum this vectors...
  28. StenEdeback

    Relativity Good introductory book about general relativity at undergraduate level

    Summary:: I am looking for a good introductory book about general relativity at undergraduate level. I am looking for a good introductory book about general relativity at undergraduate level.
  29. SirMadame

    I Self-Study General Relativity: After Multivariate Calc in HS

    I just finished multivariate calculus (without any linear algebra experience yet) and I am seeking out a path to understanding General Relativity. I am wondering what are the mathematical fields after multivariate calculus that I need to master before beginning to understand GR, and what...
  30. starkreactor

    I Thought Exp: Gen Relativity & Time Dilation

    I am trying to understand a thought experiment I just posed, which is: if an observer is traveling near the speed of light, and sends out two photons; one in the direction of travel and one in the opposite direction, how does general relativity account for time dilation? The photon "in front"...
  31. berkeman

    RIP General Chuck Yeager, dead at 97

    https://www.cnn.com/2020/12/07/us/chuck-yeager-death/index.html What an amazing life. I'm glad we had him all the way to 97!
  32. phoenix-anna

    B First Experimental Confirmation of GR

    Trying to understand how Einstein predicted the appearance of stars during the solar eclipse around the turn of the 20th century (the first experimental confirmation of General Relativity, I believe). My impression, which is not physically correct, is that the sun attracts the photons as they...
  33. Martian2020

    B General Relativity and the curvature of space: more space or less than flat?

    General relativity. Curvature of spacetime: ok. time dilation: ok. What about space? Curvature is intrinsic and given by complex equations. But could we definitely say is there more space between 2 points along curved space through the star than would be through flat space (no star there) or...
  34. PhysicsTest

    Power Calculation of general electric circuit

    I am trying to calculate the power calculation of a general circuit with voltage leading the current by a phase difference of ##\theta##. The instantaneous voltage is given by ##v = V_m\sin(\omega t +\theta) ; i = I_m\sin(\omega t) ##. The instantaneous power is then ##p = V_m I_m \sin(\omega t...
  35. Algr

    Would a worldwide quarantine help? --moved to general discussion

    Summary:: Covid 19: How effective would a two week worldwide lockdown be? How effective would a two week worldwide lockdown be against Covid 19? In March when the news first hit, the US went swiftly into a hard lockdown. But things have mostly let up since then with mostly just masks, and...
  36. The Bill

    Geometry General Ellipsoid Area Formula: Detailed Explanation

    I'm looking for a source that fully derives the complete formula for the surface area of a general (triaxial) ellipsoid. I'd prefer a source that has more than just a full derivation, but also has a fair amount of prose discussion on this topic. Some historical context would be nice, as well...
  37. D.S.Beyer

    B Lagrangian Point in General Relativity

    Is there a relationship between the Lagrangian ‘hill diagram’ and the spacetime curvature embedment graphs? The Lagrangian map shows effective potential, which deals with centrifugal force. As centrifugal force is a fictitious force (and gravity is as well), I would assume the underlying...
  38. SamRoss

    I Gravitons Replacing General Relativity: Can it Work?

    Einstein's theory describes gravity as a curvature of spacetime. As such, everything is affected by it. This includes light, which has no mass, as was made clear for the first time during the famous 1919 solar eclipse. In the standard model, the cause of gravity is supposed to be gravitons...
  39. patric44

    The general equation of the superposition of orthogonal waves?

    hi guys i was trying to derive the general formula of two orthogonal waves $$x^{2}-2xycos(δ)+y^{2} = A^{2} sin(δ)^{2}$$ where the two waves are given by : $$x = Acos(ωt)$$ $$y = Acos(ωt+δ)$$ where ##δ## is the different in phase , i know it seems trivial but i am stuck on where should i begin...
  40. karush

    MHB General Solution of Differential Equation System

    $\tiny{27.1}$ 623 Find a general solution to the system of differential equations $\begin{array}{llrr}\displaystyle \textit{given} &y'_1=\ \ y_1+2y_2\\ &y'_2=3y_1+2y_2\\ \textit{solving } &A=\begin{pmatrix}1 &2\\3 &2\end{pmatrix}\\...
  41. A

    I General Generator of Lorentz Transformation in Hamiltonian Formalism

    In the Hamiltonian formalism, the space-time transformation are realized via canonical transformation, and the transformations are generated by Poisson brackets of certain functions of phase-space variables. In Newtonian mechanics, Galilean boosts are generated by the sometimes called dynamic...
  42. S

    General Relativity and Inertia

    I haven't gone to movie theaters in 6 months. So I have to be content with online movies, and reading sci fi models, and maybe writing a short story or two. If a flying ship could travel thousands of miles per second, it can't suddenly turn 90 degrees because of inertia, the occupants would be...
  43. T

    A Alternative theories to General Relativity

    Hey there.Have you read about the alternative theories proposed by other scientists to General Relativity?So far General Relativity still stays the most accurate.But if we could generalise it?Perhaps try with some new maths like complex differentiable manifolds or Lie groups or another...
  44. AHSAN MUJTABA

    General Relativity: How many Christoffel symbols?

    Actually I know there would be some permutations used here. I know how to calculate the symbols but estimating is quite a new thing to me
  45. F

    I Why Does Special Relativity Not Contradict General Philosophy?

    I hear that philosophy refuse to "relativity concepts"(e.g relativity moral).Relativity theory says about the relativity of spacetime.I do not understand why special relativity does not contradict with general philosophy?(I know the theory Idea Form of Plato)
  46. LCSphysicist

    I What are current Physicists' general positions on the Copenhagen Interpretation?

    Actually, is not a doubt as a question, in which there is wrong or right. I just want to update myself with respect to the current physicists opinion about the Copenhagen interpretation of Bohr and Heisenberg. Summarizing, there is a consensus among the majority? In another words, there is still...
  47. S

    Courses Statistical Physics vs QFT vs General relativity

    Good day, I'm starting my master in physics, and it's time for me to choose my courses. I will take one or two of the following three courses, which are: Statistical Physics, QFT and General relativity. Now, I'm finding it very hard to decide as on the one hand, I'm interested in QFT and...
  48. F

    I General guidelines on the physics of flows at junctions?

    Let's start with a configuration in which one tube, A, splits into two, B and C. We can write the relationship $$A_A v_A = A_B v_B + A_C v_C$$ When I first saw this formula (which was very recently), I wanted to solve for ##v_B## and ##v_C## given all other values. I can't of course. There are...
  49. S

    B Light Clock & Length Contraction in GR

    Hi, can i use a light clock made out of mirrors a distance appart to measure whether there is length contraction in different regions of spacetime? If the clock speeds up then the distance between the mirrors decreased. If the clock slows down the distance between mirrors increased.
  50. M

    Derive a general expression for the dilution of saltwater

    I know that it will take 3 washings to reach the desired purity of sand, and that "N-1" is an exponent in the general expression, but I am stuck beyond that.
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