Initial state Definition and 20 Threads

[Moderator's note: Spin off from previous thread due to topic/level change.] Although the initial state of the universe is subject to much speculation, it seems to have started as all (or almost all) energy with particles being created out of photon-photon interactions.

I was thinking about ballistic pendulums and the symmetry they exhibit. In the simplest case, you have one ball that begins at a certain height and collides with another ball at rest. You can calculate via conservation of momentum and energy the new velocities and max vertical displacements...

Theoretical problems often begin with "given a system in state ψ0" For example, the 2-slit experiment begins with the assumption of a plane wave incident on the slits. I had always understood to this mean some prior set of measurements had been made to determine the initial state. But how can...

I’m confused about how you find the vector |s;s⟩ to use in the general equation |θ,ϕ⟩=exp(−iϕS3) * exp(−iθS2) |s;s⟩ For spin Coherent states (From http://www.scholarpedia.org/article/Coherent_state_(Quantum_mechanics)#4._Spin_Coherent_States Eq 12) Or how you find the vector |j,m=j⟩ to use...

I've found online that the coherent state of the harmonic oscillator is |\alpha \rangle = c \sum_{n=0}^\infty \frac{\alpha^n}{\sqrt{n!}} | n\rangle where |n\rangle = \frac{(a^\dagger)^n}{\sqrt{n!}} |0\rangle and |0> is called the initial state. I've some code where I need to have this...

Predicted Heat Death of the Universe In his thought provoking documentary “Wonder of the universe” ( ) Professor Brian Cox explains the thinking behind current predictions for the “Heat death of the universe”. He explains the predictions through the effect of the second law of thermodynamics...

Hi comunity! I need to make a code o a normal distribution of velocities, starting whit a random secuence uniformly distributed between [0,1]. I am using FNT95, with Plato. I want to obtain a ''for'' bucle with I=1,N for the velocities. It is importan for the distribution to have sigma defined...

I have created an initial state code with perodic boundary conditions and normal distribution of velocities. I not know where is the problem, when I compile the computer detect the 112 error. Could anyone help me please? Thanks! the code is...

Do you think we will ever be able to create a simplified computer simulation of the universe using the cosmic microwave background as the initial state that would generate the true locations of galaxies or at least galaxy clusters, and then be able to find our own galaxy or galaxy cluster within...

I have this equation u0(x) = a0x2(1-x)2 for 0≤ x ≤ 1 = 0 for x>1 i have to investigate how will a solitary initial state such as the one above deform as time goes on. I know it will not deform if c is constant. when they say I must do this by a well-lnown method and produce video...

Hi :) I'm reading a didactic paper and the author defined the initial state ket as |\Phi_{in}> = {\int}dq\phi_{in}(q)|q> where q is a coordinate and \phi_{in}(q) = <q|\Phi_{in}> = exp\left[\frac{-q^{2}}{4\Delta^{2}}\right] I don't know if I'm missing something but isn't this definition a...

Homework Statement Consider the Hamiltonian H=0.5p^2+ 0.5x^2, which at t=0 is described by: ψ(x,0)= 1/sqrt(8*pi) θ1(x) + 1/sqrt(18pi) θ2(x), where: θ1= exp(-x^2/2); θ2=(1-2x^2)*exp(-x^2/2) a) Normalize the eigenfunctions and rewrite the initial state in terms of normalized...

Homework Statement Suppose that the initial vector P0 is not given and instead we are given that at time t=299 the state vector is P_299=[.1 .1 .8]. Than find P_300, the state vector at time t=300 Homework Equations I also know from the problem it is referencing that the transition...

In textbooks (such as Griffiths, for example), the general method for a solution to the Shrodinger's equation for a single particle, for some V(x), is given as : 1. Get the stationary state solutions 2. Combine them into a linear combination and figure out the coefficients from the known initial...

Hi all Another question (sorry) Water vapour in the air will phase shift back to liquid when it reaches its Dew Point temp (Partial Pressure = the Saturated Vapour Pressure), OK I have this. For this phase shift I assume that there are Condensation Nuclei and these nuclei are at a lower...

In the following video Penrose states that the Universe was so special and organized at its initial state the figure describing it would be "at least" 10^123. Begin at 4:50 Has this figure or any other figure been confirmed? Where can I go to find out if this is true or not. I found...

I was wondering if it were in actuality possible to assume the universe was created from a big bang, as it seems we used current understanding of the laws of physics as they apply to us now, and extrapolated back. Could it be possible that the boundary conditions we form our laws of physics upon...

I have 3 questions regarding BM 1. Trans-plankian problem Let’s roll all processes back in time from the God’s view (so we see all BM particles and their trajectories are not hidden to us). Like any single-history deterministic theory in BM the future is ‘encoded’ in the past, so, the deeper...

Homework Statement At t=0, the particle is in the eigenstate S_x , which corresponds to the eigenvalues -\hbar \over 2 The particle is in a magnetic field and its Hamiltonian is H=\frac{eB}{mc}S_z . Find the state at t>0. Homework Equations Eigenstate of the Sx is...

For processes of particle decay and inelastic scattering, quantum field theory (QFT) predicts well the probabilities of various final states for given initial states. Technically, this is described by the S-matrix, which is the unitary-evolution matrix describing the transitions from t=-infinity...