Collapse Definition and 466 Threads

electron two slit experiment with gradual "collapse"? Just read about the two slit experiment with electrons where you try to find out through which slit the electron went by "shining a light on it" (Feynman lectures on physics I-37-7). I try to summarize the statement and then have a question...

Wavefunction collapse ==> increase in entropy?? I just read an article in Scientific American by Sean Carroll, called something like Does Time Run Backward in Other Universes. In it, he says that the reason wavefunctions only collapse and never un-collapse is because collapsing represents an...

I'm not sure the double-slit experiment is one such example, maybe I have not understood it yet. This experiment shows the wave nature of light due to the wavefunctions of photons. But how does it show a particle of zero size that is not just a burst of waves?

In the book 'Quantum Physics', Alastair Rae uses polarized photons and photon detectors to describe many effects observed in quantum physics. In his typical setup, photons are passed through a polarizer and exit it through two different channels depending on the polarization \phi or...

Homework Statement Homework Equations (this is ~Fetter & Walecka Quantum theory of many-particle systems problem 1.2b) Homogeneous system of spin 1/2 particles, potential V. Expectation value of Hamiltonian in the non interacting ground state is E^{(0)} + E^{(1)} = 2 \sum_k^{k_F} \frac{\hbar^2...

The preliminary report is out on the bridge in Minneapolis that collapsed last year, The BBC claims they found that some of the gusset plates that failed were only half the thickness of the rest and are calling it a design error. Although they cannot find the original design so it's not clear...

We know about formation of (stellar mass) black hole under gravitational collapse in classical theory. But what is the result according to full quantum mechanical treatment? Can anybody tell? I have found one paper according to which, formation of trapping horizon can be questioned in...

Hello all, Ok I`m new to this forum so please don`t shout at me if this is a silly question :) I have been wondering why it is that planets like Jupiter which have the gravitational pull to have moons orbiting them - why they then don`t collapse into solid spheres under their own gravity?

Reading Sam Treiman's http://books.google.de/books?id=e7fmufgvE-kC" he nicely explains the dependencies between the Schrödinger wave equation, eigenvalues and eigenfunctions (page 86 onwards). In his notation, eigenfunctions are u:R^3\to R and the wavefunction is \Psi:R^4\to R, i.e. in contrast...

Been a while since I posted here. I gave up on pursuing a career in engineering or physics so forgive me for any errors, but something occurred to me recently. If you are familiar with general relativity then you know this: {t_o=t_f}\sqrt{1 - r_o/r} where {t_o} is time passed close to...

assume that i have a photon field, which is in a coherent state. now i detect a photon of this field, i.e., my detector absorbs a photon from this field. my question is, what state will the field collapse into? this question may be not so trivial as the examples most quantum mechanics...

Homework Statement Under some circumstances, a star can collapse into an extremely dense object made mostly of neutrons and called a neutron star. The density of a neutron star is roughly 10^{14} times as great as that of ordinary solid matter. Suppose we represent the star as a uniform...

French economy- why hasnt it collapsed yet ? Hey i live in France, and i wonder how the French economy can keep it itself from collapsing I mean : they have all sorts of taxes (regular taxes, social security, retirement, and all sort of others) these taxes often take u away 50 percent of ur...

I am just beginning to understand this concept. Some help would be appreciated. Let me know if I am wrong in saying the following: "The wave function (say \Psi] collapses to an eigen vector of the operator corresponding to the physical quantity(say \lambda) being measured. This is because the...

Can the wavefunction collapse not be derived or is it really an axiom? How can the answer to this question (yes or no) be proven? If it is an axiom, is it the best formulation, is it not a dangerous wording? Let's enjoy this endless discussion !

I won't debate on the "wavefunction collapse" ... ... since this is just a lazy debate started from a misunderstanding. Clearly when a small system interacts with a measuring device, the wave function of the small system just loses any meaning. There is only one "larger" wavefunction for...

some very beautiful experimental work, observing the progressive collapse of a a wavefunction. beautiful illustrations too I didn't see this discussed here so decided to start a thread on it Here's the abstract http://arxiv.org/abs/0707.3880 Progressive field-state collapse and...

some very beautiful experimental work, observing the progressive collapse of a a wavefunction. beautiful illustrations too I didn't see this discussed here so decided to start a thread on it http://arxiv.org/abs/0707.3880

why is not need for introducing a true collapse in bohmian interpretation?

Why is it that when observing an electron or photon it causes the wave function to collapse, surely the photons that cause this collapse were still "colliding" with it when we wern't looking. Or does it only collapse the wave function from the observers viewpoint? (I'm abit of a noob so if...

This belongs under Civil/Structural, but is a Mechanical Engineering issue as well. Potential Flaw Seen in Design of Fallen Bridge, NYTimes, Aug 9 http://www.nytimes.com/2007/08/09/us/09bridge.html The use of Gussets is standard in steel bridges. They form the joints shared by various...

This image shows the ground supports of the bridge before the collapse: http://www.wmur.com/2007/0802/13805989_240X180.jpg taken from: Nation's Bridges Face Immediate Inspection. Fifth Victim Found; President Bush To Visit Minneapolis UPDATED: 9:20 am EDT August 3, 2007...

Hi all I know I raised a similar question in the thread "Wave particle duality", but it is already so full of many other questions, that I'd not be able to discuss this topic fully there. So, in the double slit experiment, if a photon observes an electron, the interference pattern...

Why doesn't a star collapse in the early stages of its life instead of the later. You would think that with less gas at the end stages gravity would weaken and not allow a black hole.

In the video at http://www.spikedhumor.com/articles/108195/Real_Life_Creature_Assassin.html they say something about the "bubbles momentarily reach the temperature of the sun". I don't understand this bit at all, or how this mechanism works.

If a star is spinning very fast before it collapses, then as it collapses it's going to spin faster, like a skater bringing his or her arms into speed up rotation. Intuitively I'd imagine that there's no way a star could ever be spun up to the point where its outer edge speed would exceed c...

Civilisations tend to emerge when the conditions are right for that, they tend to build some impressive structures like temples, pyramids, cathedrals, etc and usually disappear again. The reasons of the collapse may be famines, climate change - drougths, wars, pandemics etc. So here are these...

I have read several articles about this lately. The bees apparently fly away and never come back. Is this something new or just a periodic natural occurrence? I really couldn't find anything on Google that gave an adequate answer. I know there was a mite infestation that killed millions...

http://video.google.com/videoplay?docid=964034652002408586 Here is a video of Professor Jones of BYUniversity presenting a lecture about the collapse of the WTC buildings. He talks about the stresses on the steel columns imposed by the heat of the fires and how they were not great enough to...

This may be a repeat, but I don't think the earlier shorter post survived the recent PF upgrade, at least I couldn't find it. This is a better post anyway :-). I've been trying to understand the Poisson-Israel model of a charged black hole recently. (The model is also expected to provide...

On reading Vilenkin's recent paper, I believe he fails to refute the CNS conjecture. This is for a very simple reason. When Smolin has discussed the conjecture he has made it clear that it concerns black holes formed by stellar collapse. Vilenkin confuses the issue by attempting to switch...

I found a layman's explanation of the wave characteristics of subatomic particles in the form of a "Dr.Quantum" video from "What the Bleep do we know?". Aside from the parapsychological junk in the last 2/3rds of the movie, the explanations of quantum properties seemed mostly accurate and...

This is my analysis:1)quantum can have two states at one time:0 and 1.So n QBits have the volume 2^n. 2)when it's observed,the quantum state will collapse to a certain one. So the comtradiction is evidence:the information of the 2^n Qbits disappear when I only read n Qbits from it. Ok...if...

Could the process of star formation in a collapsing gas cloud transform the process of virialisation and ultimately promote the formation of a central black hole? Consider the following idealised and oversimplified scenario. Suppose a gas cloud massive enough to generate vast numbers of...

Can blind people collapse the wave function or is the wave collapse restricted to the sense of sight? Can other senses such as smell, taste, hearing and feeling collapse the wave function? Does the wave function only collapse on the surface of an object? Thanks RAD

is the idea that collapse cannot be defined as something that occurs, generally known and accepted? thx

Does the collapse of the wave function really happen when someone observes it or is collpase a fluke of measurement? Thanks for your input and time. RAD4921

i remember in high school my physics teacher used the example of tacoma bridge to teach us resonance. what exactly is it that caused tacoma to collapse? how is forced resonanace different from normal resonance?

Hello. In QM we can determine the probability of any event ocurring given the wavefunction. Once we actually take a measurement the particle 'picks' a state to be found in. so my question is how do we know a priori that the particle is in two or more states at the same time before we make a...

Scientists wan't to know where wave function collapse occures. I have found at least one. Take the experiment of shooting electrons through two holes that are close together and seeing where they land at a detection screen on the other side. If you shut one hole you get a particle or lump...

It is a controversial issue of whether or not Thomas Nast's cartoons lead to the collapse of the Tweed ring. Some view him as a rasist and that the Times and Samuel Tilden did more, but others feel that he was able to effectively shift the opinion of the general population. I would like to see...

After a certain external field strength can it collapse?

http://arxiv.org/abs/astro-ph/0507340 Nucleosynthesis of PopIII Core Collapse Supernovae and the Abundances of Extremely Metal Poor Stars Authors: Marco Limongi (INAF-OAR), Alessandro Chieffi (INAF-IAS) Comments: 6 pages, 4 figure, Proceedings of the IAU Symp. No. 228 "From Lithium to...

Does string theory provide an explanation for the collapse of the wave function in QM? Thank you in advance for your comments.

I have read the following in a textbook: "In emphysema, phagocytes release the enzyme elastase, which causes the alveoli to lose their elasticity. This interferes with their ability to relax and thus your ability to exhale. This also causes the bronchioles to collapse, which further prevents...

If we treat space and time equally, in classical QM, by defining, formally, a time observable (and a conjugate observable), we can see that the postulates of QM have a simpler form: we can derive the unitary evolution from the measurment collapse postule. (We use the units hbar=1). Just take...

Photon "Wave Collapse" Experiment (Yeah sure; AJP Sep 2004, Thorn...) There was a recent paper claiming to demonstrate the indivisibility of photons in a beam splitter experiment (the remote "wave collapse" upon "measurement" of "photon" in one of the detectors). 1. J.J. Thorn, M.S. Neel...

"The collapse of Soviet Union hit World's Science and Technology Development hard." What do you think of this remark?

I changed my mind, I'm not fickle, th stethescope was all i could remember... Anyway, apparently the tacoma bridge collapse was due to the bridge 'vibrating', and obviously the supports couldn't hold it... If you know anything about how the sound part of physics fits into this your help...

http://news.bbc.co.uk/2/hi/health/3614180.stm Loud music lung collapse warning Loud music can do more than damage your hearing - it can also cause your lungs to collapse. Experts writing in the Thorax detail four cases where loud music fans experienced the condition, known as a...