Infinite Definition and 1000 Threads

  1. P

    MHB Infinite Natural Numbers: First-Order Logic Formula Explained

    There are an infinite number of natural numbers. Why is that? Well this follows from the following facts: (i) There is at least one natural number. (ii) For each natural number there is a distinct number which is its successor, i.e., for each number $x$ there is a distinct number $y$ such that...
  2. JTorn

    Why doesn't a real Infinite Redshift Limit occur at R+ for Kerr BHs?

    As I have studied before, I found that Infinite Red Shift occurs where gtt = 0 but this exercise says that on Kerr's Black Hole it doesn't really work like that. Right now I'm blocked because I didn't find anything on the internet about it so I don't know how to show this phenomenon. Any help...
  3. Boltzman Oscillation

    Solving Schrodinger's Equation for a Particle in an Infinite Box

    Firstly, since there is no condition for the z axis in the definition of the potential can I assume that V(x,y,z) = .5mw^2z^2 when 0<x<a, 0<y<a AND -inf<z<inf? If so then drawing the potential I can see that the particle is trapped within a box with infinite height (if z is the...
  4. Ehyeh Asher Ehyeh

    I Is Our Universe Finite or Infinite?

    Summary: No answer could be more important to the assumptions and approach to cosmology. The overwhelming bias is a finite Universe, and could this be a mistake? The measurements across the observable universe strongly indicate a Gaussian Curvature of Zero(Flat). Does this prove that Spacetime...
  5. Cocoleia

    Infinite square well, dimensionless Hamiltonian..

    I have always seen this problem formulated in a well that goes from 0 to L I am confused how to use this boundary, as well as unsure of what a dimensionless hamiltonian is. This is as far as I have gotten
  6. C

    A Help required to sum an infinite series in a given equation

    Hi, I have a particular equation in a paper, wherein the author specifies an infinite series. The author has apparently found the sum of the series and calculated the equation. Can anyone please help me in understanding how to sum such a series. I have attached part of the paper with the...
  7. jonander

    Newton's first law and a body on an infinite and frictionless road

    Hi everyone! I have started to study physics this month and I got to the Newton's laws. According to Wikipedia, the first law is: This definition made me wonder: If there was, let's say, a fictional road, infinite long and frictionless, and a body would move in constant velocity over it, could...
  8. G

    MHB How do you find the sum of an infinite series?

    Hi, I'm trying to solve the sum of following infinite series: \sum_{k=1}^{\infty} \frac{{k}^{2}+4}{{2}^{k}} = \sum_{k=1}^{\infty} \frac{{k}^{2}}{{2}^{k}} + \sum_{k=1}^{\infty} \frac{4}{{2}^{k}} Using partial sum we can rewrite the first series: \sum_{k=1}^{\infty}...
  9. badatcalc

    Question about infinite series

    To anyone that can help me with this - You have to pick the FIRST correct reason. Work below (exception of 4 because I cannot figure it out), but in order to get the question right you must have all correct and I cannot figure it out. Any help is appreciated. [Moderator's note: Moved from a...
  10. N

    I Prove that F^infinity is infinite dimensional

    Hello i am currently struggling with a problem, F denotes either the set of all Real or Complex numbers. The aim is to prove that ##F^\infty## is infinite dimensional. First of i am not sure i understand the books definition of this collection. It says it consists of all sequences of elements...
  11. NathanRB

    Which force acts perpendicular to the side faces of an axe head?

    Say that these pictures are accurate. Personally, I think I can solve this problem, but the issue is, that I had a debate on it with my Physics teacher. This is how my teacher would solve it; my teacher says that each Fk on each side is constructed from half of F and Fx. So, F = 2 * Fk * sin...
  12. N

    MHB Infinite dimentional subspace need not be closed

    Let X=C[O,1] and Y=span($X_{0},X_{1},···$), where $X_{j}={t}^{i}$, so that Y is the set of all polynomials. Y is not closed in X.
  13. jisbon

    Electric field of an infinite charged plate

    So I figured to get e-field at point (4,4,0), I need to find the resultant e-field from the negatively charged particle and the plate ##E_{resultant}=E_{particle}+E_{plate}## ##E_{particle}=\frac{kq}{d^2}=\frac{(9*10^9)(-2*10^-6)}{4^2}=-1125N/C## Now for the plate is where I'm confused. If this...
  14. Look

    MHB Gödel Number Usefulness to Determine an Infinite Set's Completeness

    Gödel numbers are used to encode wffs of formal systems that are strong enough in order to deal with Arithmetic. In my question, Gödel numbers are used to encode wffs as follows: Syntactically (by formalism without semantics) there is set A (the set which is postulated to be infinite), such...
  15. jisbon

    Evaluating Summation of an Infinite Series

    Evaluate ##\lim_{n \rightarrow +\infty} \frac {1} {n} [(\frac {1}{n})^{1.5} + (\frac {2}{n})^{1.5} +(\frac {3}{n})^{1.5}+ (\frac {4}{n})^{1.5}+...+(\frac {n}{n})^{1.5}]## Hello. So I'm solving this question at the moment. I know I'm supposed to find out the summation of this before being able...
  16. bob012345

    Infinite Number of Image Charges?

    Consider two opposing mirrors. If they are exactly parallel planes I think there is only a single image in each but if they are slightly angled there appears an "infinite" number of reflections. Similarly, suppose we have grounded conducting planes instead of mirrors with a charge in between...
  17. M

    Non trivial solution to Schrödinger equation for 1-D infinite well

    Hello, I am trying to find the solution of Schrödinger equation on matlab. However, when I apply boundary conditions, MATLAB only gives me the solution with both coefficients 0. I want to find the solution : Asin(n*pi*x/L) You can see my code below. Could you please tell me where is my mistake...
  18. J

    Expectation of Momentum in a Classical (Infinite) Potential Well

    Okay so I begin first by mentioning the length of the well to be L, with upper bound, L/2 and lower bound, -L/2 and the conjugate u* = Aexp{-iz} First I begin by writing out the expectation formula: ## \langle p \rangle = \int_{\frac{L}{2}}^{ \frac{L}{2} } Aexp(-iu) -i \hbar \frac{ \partial }{...
  19. Kaguro

    Infinite square well centered at the origin

    The problem is: Solve the time independent Schrodinger Equation for infinite square well centered at origin. Show that the energy is same as in the original case(well between x=0 and x=L). Also show that the solution to the this case can be obtained by setting x to x-L/2 in ##\psi## in the...
  20. Math Amateur

    MHB Infinite Series .... Sohrab Exercise 2.3.10 (1) .... ....

    I am reading Houshang H. Sohrab's book: "Basic Real Analysis" (Second Edition). I am focused on Chapter 2: Sequences and Series of Real Numbers ... ... I need help In order to formulate a rigorous proof to the proposition stated in Exercise 2.3.10 (1) ... ... Exercise 2.3.10 (1) reads as...
  21. E

    B Finite & Infinite: Univerally Accepted Definitions?

    I'm troubled by what I think the 'community' considers them to be, but I'm not sure if I'm correct. It appears as though finite is thought to have both an end and a beginning, but is it true that infinite (infinity) is thought to only have no end? Is this accurate? If so, then it would seem like...
  22. HarishRR

    Flux from an infinite charged sheet

    I tried finding the cone's Flux and from there i have no idea ,can anybody pls help me ? Thanks in Advance Regards Harish R
  23. Miles123K

    Normal mode of an infinite spring pendulum system

    First I worked out the dispersion relations, which is pretty easy: ##M \ddot x_j = K x_{j-1} + K x_{j+1} - 2K x_j -mg \frac {x_j} {l} ## (All t-derivatives) We know ##x_j## will be in the form ##Ae^{ijka}e^{-i\omega t}## so the above becomes: ## -\omega^2M = K (e^{-ika}+e^{ika}-2)-\frac {g}...
  24. nomadreid

    Computational learnability: jump from finite to infinite

    Summary: Starting on basics of computational learnability, I am missing the key intuition that allows results about finite processes to reference results from the infinite domain. Snowball: (a) Hazard brought my attention to a popular article...
  25. fazekasgergely

    Infinite series to calculate integrals

    For example integral of f(x)=sqrt(1-x^2) from 0 to 1 is a problem, since the derivative of the function is -x/sqrt(1-x^2) so putting in 1 in the place of x ruins the whole thing.
  26. S

    Potential at the origin due to an infinite set of point charges

    Summary: Potential at origin of an infinite set of point charges with charge (4^n)q and distance (3^n)a along x-axis where n starts at 1. From V=q/r, we find Vtotal=sum from 1 to infinity of (4/3)^n(q/a), which diverges. There cannot be infinite potential because there is a finite electric...
  27. M

    An electron is fired at a nonconducting infinite sheet

    I've been thinking about this problem for some time now and think that I need to find E to solve for σ, but I have no idea how to go about that. How do I approach this problem?
  28. entropy1

    I MWI -- Infinite number of worlds?

    If we would, for sake of argument, adopt the MWI interpretation, then are there wavefunctions (like for instance position) that have a continuous probability spectrum, and will MWI then propose that there are an infinite number of actual universes that each represent a position in that...
  29. NavStar

    Static free charge in a time varying infinite uniform magnetic field

    Hello, Let's imagine we have an infinite plane (or large enough compared to the region of interest and measurements) pierced in normal direction by magnetic field B which is uniformly distributed but time varying. For the sake of simplicity we'll presume the magnetic induction is linearly (and...
  30. A131313

    Why is the Kinetic Energy 0 at an infinite distance away from a point?

    Hello! I'm trying to understand the concept of escape velocity, and I know you equate the initial mechanical energy to the final mechanical energy, where the final mechanical energy is at a distance of infinity. I know that the gravitational potential energy approaches 0 as the distance r gets...
  31. K

    Energy density due to infinite uniform line charges

    Let ##(x_1,y_1)## and ##(x_2,y_2)## be the point where the rods intersect the ##x,y## plane. I know that on any given point there will be the superpositions of ##E_1=\frac{2\lambda}{4\pi \epsilon_0}\frac{1}{(x-x_1)^2+(y-y_1)^2}\hat{r}_1## and ##E_2=\frac{2\lambda}{4\pi...
  32. R

    Find ψ(x, t) and P(En) at t > 0 infinite well

    I am currently stuck trying to work this out. I have an infinite potential with walls at x=0 and x=a, with the initial state: $$ \psi(x,0) = A_2(exp(i\pi(x-a)/a)-1) $$ I am trying to find psi(x,t). I know that $$ A_2(exp(i\pi(x-a)/a)-1) = A_2(-exp(i\pi/a)-1) $$ And this enables me to find...
  33. A

    Spin-##\frac{1}{2}## particles in infinite square well

    Homework Statement Construct the four lowest-energy configurations for particles of spin-##\frac{1}{2}## in the infinite square well, and specify their energies and their degeneracies. Suggestion: use the notation ##\psi_{n_1,n_2}(x_1, x_2) |s,m>##. The notation is defined in the textbook...
  34. K

    Half infinite cylinder uniform charge

    Homework Statement Hi. in my problem there is an infinite half cylinder uniformly charged with ρ. What is the force is the cylinder is making on a test charge on a charge located on the position that is shown on the following picture: Homework Equations ∫qdQ/(r2) The Attempt at a Solution Well...
  35. Zack K

    I Why can an infinite area have a finite volume or SA?

    I have a calculus 2 midterm coming up and given the exam review questions, this seems like this question can potentially be on it. I've tried to look it up, but I always find the famous painters example, which I don't find satisfying.
  36. C

    Conflict Between Infinite energy levels and Valence Shells

    Homework Statement I'm having trouble understanding the existence of valence shells. I understood that valence shell is the last energy level for the electrons to populate around an atom. But, according to Bohr model , an atom can have infinite energy levels , so I don't understand: How can...
  37. Mr Davis 97

    I Polynomial of finite degree actually infinite degree?

    ##1+x+x^2 = \dfrac{1-x^3}{1-x} = (1-x^3)\cdot \dfrac{1}{1-x} = (1-x^3)\sum_{k=0}^\infty x^k##. Isn't this a contradiction since the LHS has degree ##2## while the RHS has infinite degree?
  38. S

    Infinite number of identical charges r=a2^n

    Homework Statement Homework Equations V=k∑q/r E=-dV/dsThe Attempt at a Solution I found part A plenty fine, 2kq/a From here, I thought that the derivative of -V would give me the electric field, giving -2kq/a^2, but that's not the answer according to what my professor sent. I'm wondering...
  39. navneet9431

    What Is the Limit of (x - tan(x)) / x³ as x Approaches 0?

    <Moderator's note: Moved from a technical forum and thus no template.> $$\lim_{x\rightarrow 0} (x-tanx)/x^3$$ I solve it like this, $$\lim_{x\rightarrow 0}1/x^2 - tanx/x^3=\lim_{x\rightarrow 0}1/x^2 - tanx/x*1/x^2$$ Now using the property $$\lim_{x\rightarrow 0}tanx/x=1$$,we have ...
  40. navneet9431

    B 1 to the power of infinity, why is it indeterminate?

    I've been taught that $$1^\infty$$ is undetermined case. Why is it so? Isn't $$1*1*1...=1$$ whatever times you would multiply it? So if you take a limit, say $$\lim_{n\to\infty} 1^n$$, doesn't it converge to 1? So why would the limit not exist?
  41. Clara Chung

    Gauss law two infinite plane question

    Homework Statement Homework EquationsThe Attempt at a Solution How do you know the left plate (or the right plane) produces a field (1/2ε) σ to the left and right? How do you apply Gauss Law? For one infinite plane, we can use Gauss law because of symmetry, so we can assume the electric flux...
  42. arturo

    E-field from one end of an infinite non-conducting rod

    Homework Statement Homework Equations dE= k dq/r2 The Attempt at a Solution [/B] I started off taking a derivative of q(x). dq = -qo/l ⋅ e-x/ldx Then, I decided that r was the distance x along the rod + .02m. r=(.02+x) Following that, I plugged everything into the formula: dE = k⋅qo/l...
  43. G

    Rocket equation without infinite small variables

    Hey, I'm tutor for theoretical physics for first year students and I found a question that I couldn't answer so far. It's about the rocket equation. I tried to derive the acceleration without using infinite small variables, but somehow there is one term left that shouldn't be there. In the...
  44. K

    Heat diffusion into an infinite rod

    I have recently been curious about heat diffusion. If there is space in one dimension with any kind of temperature dispersed throughout, then the heat equation states that the derivative of the temperature with respect to time at any point equals some constant (k) multiplied by the second...
  45. JD_PM

    Infinite Square Well -- Instantaneous expansion of the Well

    Homework Statement My doubts are on c) Homework Equations $$< H > = \int \Psi^* \hat H \Psi dx = \frac{2}{a} \int_{0}^{a} sin (x\frac{\pi}{a}) \hat H sin (x\frac{\pi}{a}) dx$$ The Attempt at a Solution I understand that mathematically the following equation yields (which is the right...
  46. D

    I The product of 2 infinite sums

    Hi. I know that eixe-ix = 1 but if I write the product of the 2 exponentials as infinite series I get ΣnΣm xn/(n!) (-x)m/(m!) without knowing the result is 1 using exponentials how would I get the result of this product of 2 infinite sums ? Thanks
  47. S

    Infinite light polarizers in an array

    I was wondering if I placed an infinite number of light polarizers in an array, each rotating an infinitesimal amount from the next, would I be able to get 100% of the photons shun thru them on the other side?
  48. A

    Time evolution of wave function in an infinite square well potential

    For this problem at t=0 Ψ(x,0)=Ψ1-Ψ3 Where Ψ1 and Ψ3are the normalised eigenstates corresponding to energy level 1 and 3 of the infinite square well potential. Now for it's time evolution it will be Ψ1exp(-iE1t/ħ)- Ψ3exp(-iE3t/ħ) And taking the time given in the question the time part of the...
  49. A

    Time evolution of wave function in an infinite square well potential

    Homework Statement Homework Equations For this question my ans. is coming option (3) since the time part of the wave comes out to be same for both the energy states which is (-1)^(-1/8) and (-1)^(-9/8) respectively (using exp(-iEt/ħ)). But the correct option is given option (4). Am I right...
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