Particles Definition and 1000 Threads

Let ##L## be the state space of two identical/indistinguishable particles. Let ##L \otimes L## be the state space of the combined system formed by both particle. If the particles were distinguishable, ##LxL## would have four mutually orthogonal states: ## |\phi\rangle|\phi\rangle...

As we know that matter is Anything which has mass and occupies space then are the Subatomic particles like electron,proton and neutron a matter. Is electron a matter ? Is proton a matter ? Is neutron a matter ? As these particles have mass and they occupy space so they are matter, But the...

I want to ask if you can theoretically chill the particles of a black hole and if it is possible to achieve it what will happen

I´´m confused. How can a single photon in the lightspectrum with wavelength of a few hundert nanometers go through both slits in the double slit experiment at the same time. I understand the wave- particle duality and the concepts in principle. My confusion is in the context of little wavelength...

Hi Pf I am looking at the figure in wiki about quantum teleportation. https://en.wikipedia.org/wiki/File:Quantum_teleportation_diagram.PNG A wants to send a qubit to B . She receives another qubit from a spdc. so she has to make a Bell measurement on them. Has these qbits to be close in space...

In this video at 02:41 we have two particles in two separate boxes. The voice-over says that the probability that particle P1 is at x1 and P2 is at x2 is equal to the probability that P1 is at x2 and P2 is at x1. The ranges of x1 and x2 are non-overlapping and correspond to the two isolated...

How to calculate time until charged particles (Electron/Positron for example) collide starting at velocity= 0 , distance x apart: Using coulombs law, how do I get the velocity and position equation for a pair of unit charged particles? A simple reference link would be great as I know this is...

I know that there isn't any delay that depends on the distance between particles, by the time it take to signal l to arrive from point a to b , but do there is any small delay that doesn't depends on distance . like the Minimum distance between two bodies divided by the speed of light . for...

Such particles are virtual, but it should be possible to associate a basic idea with them, as this is the foundation of calculation methods. I think the concept of vacuum fluctuations in the form of virtual, fluctuating pairs of particles is something else. Is the idea of virtual exchange...

Do suspended sub-micron sized particles influence the index of refraction of a liquid?

Considering the device above, which uses electric and magnetic fields placed properly to avoid charged moving particles with velocities different from the ratio ##\frac{E}{B}## to exit, getting deflected upwards or downwards. All that is easily demonstrable by equalling the forces acting on the...

From my understanding, quantum fluctuations create particle pairs that are usually annihilated. Is it possible to use some kind of force (eg: electromagnetism) to direct and separate antiparticles from normal particles? I believe experiments have proven that it is possible to store positrons...

Should particles in superposition before quantum decoherence (many worlds) be envisioned in the same exact way as they are envisioned before wave function collapse (Copenhagen)? Clearly, the particle in Many Worlds is in a sort of superposition, but with all of the talk about one universal wave...

I'm having a hard time understanding how to treat fermions, bosons, and distinguishable particles differently for this problem. To the best of my understanding, I know that my overall state for bosons must be symmetric, and because they're spin-0, this means there's only one coupled spin state...

I tried to solve the problem in 2 ways, first using lagrangian mechanics and second by putting a rotating reference frame on the initial take-off point. However I cannot be sure if the equations of motion for the two solutions came out the same. A-) Equations of motion from Lagrangian...

Hi Pf I read that when two particles are maximally entangled , all the information is in the correlations between the particles. If we need 1 bit to describe one particles. Are two bits in the correlations? three particles may be entangled and then we need to considere 3 bits. As entanglement...

The correct answer is 'C'. Why is my working wrong?

Hello, using computation simulation, can the statistical behavior of many particles be derived through deterministic classical mechanics?

In addition to the usual alpha and beta particles visible in my condensation cloud chamber, I see occasional tracks that seem highly energetic -they easily penetrate the entire width of the cloud chamber (10-12 inches) going in one side and out the other. More mysteriously, their orientation is...

i consider a pair of two level particles which can be up or down. this pair is described in the tensor product by the unitary vector (cos(\theta) (du + ud) + sin(\theta) (dd + u)) /\sqrt 2 i take its density matrix , trace it on one of the two particles and find the density matrix of each one...

This problem got me kinda confused since I cannot really understand the question... who tells me how the energy dissipated in this case? Has it all transformed into heat to cause the coalesce of the two particles, or ar the two particles now merged together still traveling with a certain amount...

Hi people. Having as uncertainty principle that ΔE Δt≥ h/4Pi, why Δt≤ h/4PiΔE to allow the existence of a virtual particle? How ≥ becomes ≤ ? I think... real particles must obey ≥ so any particle that do not obey that is a virtual particle and thus why virtual particle needs to obey Δt≤...

Some background, I am an undergraduate electrical engineering student with a knack for physics. I plan to attend graduate school for physics but for the meanwhile I've only taken an undergraduate course in QM mechanics, which used griffith's book, and a modern physics course, which covered some...

Hi my name is tim. I have a new found like of the inner workings of or universe , and am currently considering which field i should go into. As of now I am considering computer science. But to me, in my opinion, we as in humans created computers, therefore the science is technically already in...

I draw the graph like this: For (b), I divided each force vector to e from p1 and p2 as x and y parts. I computed them and got Fx=-4.608*10^(-15)N Fy=-2.52*10^(-15)N However, I am not sure whether I did it correctly or not... I appreciate every help from all of you! Thank you!

Some time ago, before particles turned out to be mutable wave excitations (making Alchemist's dreams sound nicer, I guess :-) ) , to say that something was an "elementary particle" meant that it couldn't be broken down further. OK, that idea bit the dust, but now there are intrinsic...

Hello! how does one produced big ensembles of polarized charged particles (electrons, protons, muons etc.) for certain experiments? In the case of neutral particles (for example the nucleus in an atom) this could be done using a magnetic field, but I guess this won't work that straightforward...

Consider two entangled spin half particles given by the generic form of Bell Equation in Z-axis: ##\psi = (a\uparrow \uparrow + b\downarrow \downarrow)## where ##a^2+b^2=1## In a (2D) planer rotated (by an angle ##\theta##) direction the new equation can be given by: ##|\psi \rangle =...

Consider two entangled spin half particles given by the generic form of Bell Equation in Z-axis: ##\psi = (a\uparrow \uparrow + b\downarrow \downarrow)## where ##a^2+b^2=1## In a (2D) planer rotated (by an angle ##\theta##) direction the new equation can be given by: ##|\psi \rangle =...

How does LHC send same-charged particles in opposite directions?

Hi guys, I hope you all are doing great. If we take the double slit experiment for instance, before measurement particles are in a superposition of states. Once they are "measured", or non arbitrarily interfered with, their wave function collapses and only one state remains. So my question is...

In reading around, it seems that in the case of entangled particles, it is the measurement of one of the particles that causes the other one to be it's opposite spin and that there's some means of info transfer going on caused by the measurement. I'm not understanding why it would not be that...

How the number of the particles in a solution increase the probability to get adsorption on a surface? which physical terms explain this? For example when I increase the concentration of molecules in a solution I can see that the adsorption and the aggregation on the surface happen.

How a high mobility of particles over surface cause to aggregation, the professor in the class said that "high mobility causes to local equilibration and thus to a compact aggregation".. which I didn't understand..! What does he mean about local equilibration and how all connect to each other?!

If neutrinos are majorana particles does this mean that lepton number is not conserved in particle reactions? And I only noticed neutrinos are only produced when the decay of a particle to some other particles is carried by the W bosons ( weak interaction ). Is it possible the weak interaction...

I know that I need to find the equation of the line of motion of the two particles, the dot product of which with one of the options will give 0. I began with founding the coordinates of center of mass: R = (m1r1+m2r2)/(m1+m2) = (2a/3, 0, a/3) and velocity of the center of mass: V =...

Greetings, similar to my previous thread (https://www.physicsforums.com/threads/lennard-jones-potential-and-the-average-distance-between-two-particles.990055/#post-6355442), I am trying to calculate the average inter-particle distance of particles that interact via Lennard Jones potentials...

All books in analytical mechanics explain the case of a particle moving on a given static surface. But what happen if, for example, the surface is having some deformation?. I imagine that the principle of virtual work, and hence, D'Alembert are no longer valid since the normal force by the...

Hello everyone, I hope you are having a nice day, I was reading [The principles of Quantum Mechanics by P.A.M Dirac], and I was attracted to the definition of size. The book says: "If the object under observation is such that the unavoidable limiting disturbance is negligible, then the object...

So we have 5 incognits 5 equations, is not hard, but need attention. What you think about? Right? This type of question is generally more easy to solve, do you know any trick?

Hello everyone, I was doing some calculations recently regarding particle velocities for different elements at different temperatures and I have a few questions for the experts in here. Usual gas laws in my school book provides information about the velocity of particles in gases, it provides...

Starting from the center of mass energy S = (E_{1} + E_{2})^2 - (\vec{p_1}+\vec{p_2}) knowing that E^2 = m_{0}c^4 + p^2*c^2 one has S = (E_{1} + E_{2})^2 - (\vec{p_1}+\vec{p_2}) = ( m_{0}c^4 + p_{1}^2*c^2) + m_{0}c^4 + p_{2}^2*c^2)^2 - p_{1}^2 - p_{2}^2 - 2p_{1}p_{2}cos \{theta} and then...

Greetings! Suppose I have 2 particles that interact via a Lennard Jones potential $$U(\mathbf{q}_{1}, \mathbf{q}_{2}) = 4 \epsilon \left[ \left( \frac{\sigma}{r} \right)^{12} - \left( \frac{\sigma}{r} \right)^6 \right] $$ with interparticle distance ##r=|\mathbf{q}_{1} - \mathbf{q}_{2}|##. The...

I thought i could apply a conservation of momentum in this case, Apparently, this is not right, so i don't know what to do now.

In "Introduction to Quantum Mechanics", Griffiths derives the following formulae for counting the number of configurations for N particles. Distinguishable particles... $$ N!\prod_{n=1}^\infty \frac {d^{N_n}_n} {N_n !} $$ Fermions... $$ \prod_{n=1}^\infty \frac {d_n!} {N_n!(d_n-N_n)!}$$...

In Henley and Garcia's Subatomic Physics, they introduce phase space in chapter 10 by considering all the possible locations a particle can occupy in a plot of ##p_x \ vs. x##, ##p_x## being the momentum of the particle in the x direction. They next consider an area pL on this plot, and state...

So far as I understand it, a photon can split up and create particles with matter, even though the photon is massless, yes? So if a photon can be more places at the same time, it should be able to create multiple particles all at once? So how is this not Dark Matter?

If string theory is correct does it mean that elementary particles like photons, electrons, and quarks don't really exist or does it mean they do but are made of cosmic strings and so therefore are not elementary?