Recent content by throneoo

  1. throneoo

    Programs Suggestions for PhD in Quantum Gravity?

    I'm an international student currently at the end of my penultimate year in Msci Theoretical Physics in UK and am considering applying to US graduate programs that do high energy gravitational theories, in particular black hole thermodynamics. Both UCSB and UMD seem to be good choices...
  2. throneoo

    I Defining exchange statistics of anyons in terms of Berry phase

    In 2D, if we define exchange statistics in terms of the phase change of the wavefunction of two identical particles when there are exchanged via adiabatic transport (https://arxiv.org/abs/1610.09260), we would discover that this phase can be arbitrary due to the topology of relative...
  3. throneoo

    I Understanding the curvature parameter k

    From what I can gather, the curvature on space also depends on how the choice of coordinate system (or how they are cut). Would it be correct to draw such the following analogy from 3D Euclidean space? 3D Euclidean space can either be described by cartesian coordinates or spherical-polar...
  4. throneoo

    I Understanding the curvature parameter k

    Okay. So k is a parameter of spacetime, but it only characterize the curvature of 3D space? I see. Since it doesn't make sense to talk about 1D time-curvature and given that the 3D space is flat, k=0 would correspond to a Minkowski space. How is it possible if matter/energy content is non-zero...
  5. throneoo

    I Understanding the curvature parameter k

    1.) According to my understanding, k is a constant in the Robertson-Walker metric and the Friedmann equations. Its value (-1,0 or 1) is determined by observation (e.g. the bending of light) and doesn't change over time, unlike the curvature density parameter ##\Omega_k##. Therefore a strictly...
  6. throneoo

    I (Index Notation) Summing a product of 3 numbers

    That's exactly what I thought. I suppose this ad hoc matrix is not common because this type of summation rarely appears in Physics
  7. throneoo

    I (Index Notation) Summing a product of 3 numbers

    I have just begun reading about Einstein's summation convention and it got me thinking.. Is it possible to represent ∑aibici with index notation? Since we are only restricted to use an index twice at most I don't think it's possible to construct it using the standard tensors (Levi Cevita and...
  8. throneoo

    I "Moment of Inertia" in Virial Theorem

    after readig ur link i realized talking about the moment of inertia of a non rigid collection of particles does not make much sense lol. thanks.
  9. throneoo

    I "Moment of Inertia" in Virial Theorem

    Moment of inertia is supposed to be defined with respect to a rotational axis such that for a system of point masses, I=∑miri2 where ri 's are the perpendicular distances of the particles from the axis. However, in some derivations of the virial theorem (like the one on wiki), the so-called...
  10. throneoo

    SHM: Gravity-Powered Train (Brace Yourself)

    This is the result I obtained as well
  11. throneoo

    SHM: Gravity-Powered Train (Brace Yourself)

    the 2nd part of the question is still SHM, which is known to have a sinusoidal solution A*cos(ωt+Φ), where A and Φ are to be found by fitting the initial conditions given above. With a complete trajectory it should be trivial to work out the required v0. Chain rule is not required to solve the...
  12. throneoo

    A Discrete Multivariate Probability Distribution

    I believe you just need to construct (X1,X2) for each possible outcome and count them to get the fractions
  13. throneoo

    Spherically symmetric Heat Equation

    Homework Statement A ball of radius a, originally at T0, is immersed to boiling water at T1 at t=0. From t≥0, the surface (of the ball) is kept at T1 Define u(r,t)=R(r)Q(t)=T(r,t)-T1 ΔT=T0-T1<0 r,t≥0 Homework Equations ∇2u=r-2 ∂/∂r ( r2 ∂u/∂r ) =D-1∂u/∂t D>0 The Attempt at a Solution...
  14. throneoo

    Average photon energy from a galaxy cluster

    I think that would be the braking radiation as given in OP
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