Collapse Definition and 470 Threads

I have 2 questions i would really like to find an answer to: if we have a quantum pair, we can determine whether 2 quanta are entangled or not assuming that we have access to the information of both of them. so if we have a quantum "trio" instead of a quantum pair, does the information about 2...

Homework Statement I have a problem with question (b), in what follows there's a quote of the problem and its solution. (again from Bergersen's and Plischke's textbook). Homework EquationsThe Attempt at a Solution [/B] My problem is with the last expression in (d) I get 54 instead of 36. To...

Is there a theoretical limit to the size of neutron stars? It seems likely neutron stars are not simply electrons orbiting a proton so what is their life cycle? Can they just evaporate slowly by neutron decay?

I'm trying to understand the impact of past measurements, and when measurements occur. As I understand it, in the simplest case, you've got a particle emitter in the center of a circle, and a measuring plate around the circle. Here in the ideal case the particle is emitted and has equal...

When two quantum objects interact, when does this interaction destroy their superposition and when does this interaction causes them to be entangled and allow the superposition to remain.

A have seen here on forum statements that quantum collapse is interpretation dependent, for example: So I would like to ask for explanation that does not relay on quantum collapse for this phenomena: We have unpolarized beam of light. It goes trough two orthogonally oriented polarizers...

I am confused about the QM phenomenon of collapse. For example, if an electron is prepared by a magnetic field as spin right and then measured in a device determining whether it is spin up or down, it is said that the electron, which had been in a linear superposition of up and down will now...

$\newcommand{\un}[1]{\,\text{#1}}$ https://www.youtube.com/watch?v=xSVHWiZu8NM One of my relatives sent me a link to a video (above) claiming that the WTC towers must have had internal demolition in order to fall as fast as they did. I think there are good reasons to oppose the theory, but I...

I heard that the consciousness causes collapse hypothesis is hard to verify or disprove. Anybody knows why?

Why does a wave function collapse when we observe a particle? I would like to know why something that is in Super Position suddenly chooses a particular position when observed? If something is in all positions or states. How does the particle choose a particular state? What is the decision...

What are the experiments that disprove the idea that consciousness causes wavefunction collapse?

Hello! How do I find how much energy does electron radiate during one revolution if the energy radiation rate is given by Larmor Formula: dE /dt = [(− 2/3)* e2* a2]/ c3. Should I use the chain rule? At the moment I only want a hint how to solve this. With best regards

Hey All, I have a plastic vessel fully filled filled with an incompressible fluid (Water), at some time this vessel is impacted and crushed on one side (say 5% of the initial volume is lost). Only, I know the volume isn't lost, the fluid (being incompressible) will exert pressure on all...

Something about the theory of quantum measurement/collapse in the case of quantum fields... Suppose I have a field, either a scalar, vector or spinor, that I want to describe as a quantum object. For simplicity let's say that it's a scalar field ##\phi (\mathbf{x})##, where the ##\mathbf{x}## is...

Hi. I saw this: https://www.forbes.com/sites/startswithabang/2017/05/29/surprise-the-universe-has-a-third-way-to-form-black-holes/#52d7225f216d suggesting they saw a star undergo a "direct collapse" to a black hole with no supernova. Now this seems like it could be sensible -- if there's...

A clever new paper explores the notion that the reduced Planck's constant in the quantum analogy to Newton's constant for macroscopic quantities though a hybrid quantity that generalized the Compton wavelength and the Schwarzschild radius. This allows for a linkage between the Einstein equations...

Perhaps the title of this post is not quite correct because I could not find a way to abbreviate what I am asking. Picture a magneto circuit, where, an alternator is used to generate an AC flux into a primary coil of a ignition coil by means of a magnetic core (the primary is wrapped around the...

I've been reading some speculative articles about the possible quantum arrow of time which emerges through collapse and irreversibility. My question is: does collapse in the Copenhagen interpretation (or perhaps in a objective-collapse model) allow the spontaneous decrease of entropy where an...

Lets assume there is an observable represented by the operator, ##\hat{A}##. It follow (I think) that the observed values and allowed states obeys an equation of the following form\begin{equation}\hat{A}|\psi^i\rangle=\lambda_f|\psi_f\rangle\end{equation} where $$|\psi^i\rangle = initial \ \...

In Shankars "Principle of Quantum Mechanics" in Chapter 4, page 122, he explains what the "Collapse of the State Vector" means. I get that upon measurement, the wave function can be written as a linear combination of the eigenvectors belonging to a operator which corresponds to the...

I have extensively searched the internet but failed to find any exhaustive literature on the different collapse models of quantum mechanics.It would be really helpful if someone who knows can guide me on some exhaustive resources for the same.

https://link.springer.com/chapter/10.1007/978-3-540-39664-2_1 http://iopscience.iop.org/article/10.1088/0031-8949/1988/T22/016/pdf In these two experiments done back in the 80's, electrons were trapped inside a penning trap for long periods of time. They were measuring the ratio of the magnetic...

Is there any interpretation of QM that is Psi-ontic, local, and has wave function collapse?

I would like to ask this question. In the double slit experiment on wave particle duality of photon, we know that the wave function collapses and the photon behave like a particle whenever we peek. Has anyone ever placed a second double slit behind the detector to see whether a particle regain...

https://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Wigner_interpretation also schrodinger believed it, and maybe bohr too? this is such a stupid concept, it's obviously false. but clearly i must be missing out on something, people like them aren't going to believe in things that's "obviously...

What has confused me for a long time is the interaction between superposition and entanglement. That is, what happens when one member of a pair of entangled particles passes through a filter that selects for an observable that is incompatible to the observable in which the pair is entangled...

I have a concern about having some wave function psi, that is originally a superposition of many eigenstates (energies). Traditionally, it is said that the square of the coefficient of each of the component eigenfunctions represents the probability of measuring this particular energy eigenstate...

This post is a result of reading RKaster's links and I am wondering if there is some evidence that supports measurement being a two stage process. In the Stern Gerlach experiment the particles are in superposition until measured. But is the superposition ended once they enter the magnetic field...

Suppose the Copenhagen interpretation is correct. And we reverse time, what happens. If a wave function has collapsed, and we found a particle somewhere. Now, I turn back time( just hypothetically), what would happen? Would the wave function uncollapse and would the particle then appear at some...

For a science project/competition, my friend and I have the chance of building a kick butt device to dazzle the judges. Because I'm nuts about relativity and black holes (or maybe just nuts o0)), I thought maybe we could go for broke and build a transparent, pressurized box to pulverize the...

I have a simple doubt to keep things clear. Why doesn't electrons fall into the nucleus of an atom? Is it because of the high velocity of electrons? If so, at what velocity will the electron be slow enough to collapse into the nucleus?

Hello all, You all have always kindly helped me as I remember questions I have accumulated since high school days, and have never been answered. Eventually I gave up and forgot them, but as I grow old for some odd reason these things pop back up in my mind, like old ghosts from 35 years ago...

According to Sabine http://backreaction.blogspot.com/2016/03/dear-dr-b-what-is-difference-between.html you can make superposition go away by just changing the basis state.. "All this is just to say that whether a particle is or isn’t in a superposition is ambiguous. You can always make its...

Homework Statement Suppose we have a wavefunction with n=4. If we measure the orbital angular momentum along the z-direction(no spin in this problem) and get 2*hbar then what are the possible values of the total angular momentum and what is the most general wavefunction after the measurement...

It's often claimed that in Mathematical Foundations of Quantum Mechanics Von Neumann concluded that it's the observer's consciousness that collapses the wavefunction (Process 1). But I am reading Chapter 6 of the book (both original and translation) word by word, and I don't find this...

In what year was it first discovered that wormholes are non-traversable because the introduction of infalling matter caused the throat to collapse? Who discovered this?

I successfully created the fringe pattern at home with a simple laser light and a black plastic sheet with two thin cut as double-slits. I then used two mobile phone cameras at two sides in hope that the wave function of light will be collapsed. But nothing happened i.e. the fringe remained...

As far as I understand it, a nebula initially tends to have a small amount of rotation (on average) and then as it collapses under its own gravity this rotation increases significantly due to conservation of angular momentum (assuming that there is no external torque,right?!). What I'm unsure...

Suppose we measure a normalized state ##|\Psi \rangle = \alpha _0 | \lambda _0 \rangle + \alpha _1 | \lambda _1 \rangle + \alpha _2 | \lambda _2 \rangle + ...## with ##| \lambda _i \rangle## the eigenvalues of the measured observable. Is it true that, in the CI, the wavefunction collapses into...

Why does STRONG FORCE fail regarding complex structures of sub atomic particles when wave functions collapse @ entangled superpositions. Why does it not continue to function keeping the particles bound yet unentangled with the observed Eigenstate being it was originally binding such particles @...

I learned that the moment a wavefunction collapse takes place is a matter of interpretation. So, I suppose the phenomenon 'wavefuntion collapse' is something that has to be witnessed by observation at some point to be able to establish it at all! So my question is: if collapse doesn't actually...

Let suppose I have an observable ##A## with associated projection-valued measure ##\mu_A## $$A = \int_{a \in \mathbb{R}} a \cdot \textrm{d}\mu_A(a)$$ for a system in the (possibly mixed) state ##\rho##. Let ##S \subset \mathbb{R}## be a measurable subset and let ##Z = \mu_A(S)## be the...

During gravitational collapse, gravitational potential energy of the gas is converted to its internal kinetic energy so the internal energy of the clous of gas is said to be increased But isn't gravitational potential energy included in the internal energy? Shouldn't the internal energy remains...

If we measure, say, the polarisation of a photon, the polarisation state of the photon collapses along the eigenvector of the observable corresponding to the measurement. This may seem as a loss of information of the original polarisation (for it is now collapsed into another value). However...

In the thought experiment known as Schrodinger's cat a cat is placed in a sealed box, and its life or death is tied to an uncertain quantum event such as radioactive decay. If the radioactive particle decays, the cat dies. If not, nothing happens. According to probability collapse QM, as...

Not quite. But it necessarily has to be described by a different quantum model than unitary dynamics if it is an open system and the rest of the universe is not explicitly modeled. For convenience, physicists often want to describe a small quantum system in terms of only its Hilbert space, when...

I have a question. In a massive star (more than say 5 times the mass of the sun), the electron/neutron degeneracy pressure is unable to prevent the gravitational collapse. Does this imply that the Pauli's exclusion principle breaks down and two or more electrons/neutrons collapse to the same...

An interesting article on the Tacoma Narrows Bridge collapse of 1940 shown to students of physics throughout the years as an example of the power of resonant frequencies. However, the explanation was much too simple to be true. Here's the real story...

Consider a measurement of a photon after it has passed a polarisationfilter. Does the photon jump in a (polarisation-)eigenstate by passing the filter? Does the filter do a measurement? Is the filter part of the entire measurement?

Hi all, I'm a science-fiction/fantasy writer who is in the midst of outlining a distant-future (10,000+ years) story. The main parts of it I can handle (humans on Earth have gone through a cycle of Intellectual --> Dark ages with the current era being a kind of pinnacle never again achieved)...