Virtual Definition and 547 Threads

1. The problem statement, all variables and /known data Help! I'm stuck on an exceedingly simple statics problem, number 2.24 in the New Millennium edition of exercises for the Feynman lectures. The problem consists of an inclined plane (inclination angle 30 degrees) on wheels with a...

Hi guys i don't know much about physics but I am interested in learning about it i have According to wikipedia virtual particle hasnt never been observed but i think that they are wrong it has been observed in this experiment...

I was just wondering, when particles interact with a force (which would be all the time) , does it cause the wave function to collapse? If so does that mean particles interact with forces in small time periods, since we know particles exist as a probability function? I just assumed that fields...

Why is the D'Alembert's Principle ∑i(Fi−miai)⋅δri=0 stated in terms of "virtual" displacements instead of actual displacements? what does the 'virtual displacement' really means and what is its physical significance??

ok. this may sound stupid, first of all i asked this question because i have a doubt that "if a photon can see things around it will it be able to see its own reflection if it aproaches towards a mirror?" so i played a video of light being reflected in a mirror in slow motion and paused the...

1).Virtual Photons forms in pairs like particles and anti particles? or 2).by borrowing energy from future? or 3) in both ways?

In the following figure AB which is behind the mirror is virtual image of object AB placed at some point between the pole and focus. So,is virtual object something we will get if we treat this virtual image as object i.e when we place a mirror in right side of this virtual image AB ,then the...

In order to get my head around virtual particles I've created the following question. Maybe some bright person can answer this. If I can answer this question I feel I would have the required understanding to explain virtual particles to other people. In the diagram below, A is a radioactive...

Wikipedia says that virtual particles can not be observed, they are a handy concept for understanding what happens in quantum interactions, annihilating each other before they can be detected as real particles. However it also says that under certain circumstances, if they are moved apart from...

Hi everyone, I'm trying to implement the attached circuit. (the .txt is for http://www.falstad.com/circuit/) Since I only have a single power supply and I ultimately want to drive this with a battery I am powering the opamp with a virtual ground. Using a voltage divider to achieve this. Opamp...

That is, take the virtual image as the object for a second lens?

What would be the virtual particle force acting on a wire, which go's from say Earth to any part of the universe reseeding away from us at near light speed, or grater ?, would it break, and how would we compute it ? Lachlan

I've made a virtual solar system in Java3d. I'm trying to implement the orbiting of planets and ships. I get the basic formula F = G((m1*m2)/r^2))[\code] and saw a discussion here about the formula in 3d but, I don't know how to read a letter with an arrow over it, lol. Can someone help me...

I read in few places that the virtual photons have longitudinal polarization while in some papers they say virtual photons have both transverse and longitudinal polarizations. Can anyone please help me to understand this

what is the correct understanding of a virtual particle? the popular science books would have us believe that a virtual particle magically pops up out of the woodwork, steals some energy and then puts it back before it ( the particl) disappears. Like a thieving employee who steal $100 out of the...

so virtual image is my image on the mirror? If that was true, then what is a virtual object? (with examples please)

I was reading a lot that "Virtual particles are just math..." and many physicists for some reason get angry explaining it. But I suspect this point of view is interpretation-biased and is outdated for 3 reasons listed below: 1. The (mathematical) discovery of Quantum Decoherence had provided a...

from what i understand they pop into and out of existence because + 1 - 1 = 0 and because quantum mechanics... and that's the same reason we have matter in the first place, right? because we had anti matter and matter (from virtual particles, right?) in the beginning of the observable...

Hi I was hoping someone could clear something up for me, I've been set an virtual load (unit load method) question at University, that part of the question I can do however its the calculating the force on the members part that I am struggling with. The question asks for all the forces in the...

If there is such a thing as a virtual particle, is there also such a thing as a virtual wave? what would that actually mean?

Hello The textbooks about nuclear physics I have read don't explain too much about the Yukawa's model. For example, the textbook Structure of the Nucleus -by Preston and Bhaduri- finish the Yukawa's model with open questions about the "mesonic effects" by virtual pions. And my doubt: are the...

Homework Statement How can one show/prove that for a beam (hinged supports on both ends) subjected to bending due to a uniformly distributed load over its entire length, the virtual work of internal forces is equal to the virtual work of external forces? Given are the length of the beam (L)...

I was reading "Black Holes and Time Warps" by Kip Thorne, and right around p.442-443 it talks about how the quantum vacuum fluctuations that give rise to Hawking radiation from an infalling frame of reference give rise to an "atmosphere" of real, non-virtual particles in an accelerated frame...

Homework Statement The system shown in Fig. 2-6 is in static equilibrium. Use the principle of virtual work to find the weights A and B. Neglect the weight of the strings and the friction in the pulleys. Homework Equations Conservation of gravitational potential energy. The Attempt at a...

hello, I want to apply the virtual work principle to a continuous mechanical system to derive equilibrium equation, naemly, a long thin bar with one end fixed in the wall and other end applied with pressure P. but I can not derive the correct equilibrium equations. I hope some expert could give...

dear all, the virtual work pinciple can be used to derive the equilibrium equations for the mechanical systems. however, when I want to apply it to a continuous system, I found it can not give out the simple equilibrium equations. there should be something wrong with my thinking. I expect some...

As far as I know, forces are supposed to be mediated by virtual particles. Let's take the example of a magnetic field, mediated by photons. This seems to be a good idea, because it sort of eliminates the nasty concept of a field, which is just an abstract concept. This has been bothering me...

Homework Statement If you have a spherical interface between two different "media" (like air and water), and an object is placed in the one with the lower index of refraction, with the interface being convex toward the object, how can you tell if the image will be real or virtual? Here's a...

I understand a virtual particle is not technically a particle, but more of a disturbance in a field. I can't seem to wrap my head around the concept and why it has large implications.

While deriving lagrangian equation using D'Alembert's principle, in Goldstien, they defined a variable called "virtual displacement". Why do we need a concept called virtual displacement? What is its signigicance in classical physics?

Hi everyone, This is my first post. Years ago I read in a science magazine that (at least according to a certain theory) every shell electron would be accompanied by one (or was it two?) virtual neutrino(s). At least that's my recollection of what I read. I know it sounds a little crazy. I...

If virtual particles are constantly popping in and out of existence all around us, what gravitational effect does this have? Even if they are here for the briefest of moments they should be effected by gravity and have their own gravitational effect on other matter...shouldn't they?

Hi, I have a thought experiment I'd like to share along with a couple of quotes. First, we consider the moment when a body goes from have exactly zero charge to a +Q charge. At that moment, by definition of E field a distance r from point charge q, we have a field propagating from point...

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This oft-referenced picture depicts a simulation of virtual particles popping into and out of existence in the empty space inside a proton, ie between the quarks: http://bsturge93.files.wordpress.com/2014/02/empty-space.jpg?w=300&h=242 My question is whether the intensity of this popping...

I understand that virtual images are formed when two rays APPEAR to meet and do not actually meet (lenses and mirrors) and that is why we extend the reflected (or refracted) rays behind. But that is as far as the drawing goes. What is actually happening to the rays to form a virtual image? (They...

My understand is, the virtual particle-antiparticle pairs created under uncertainty principle are not the same as the traditional particle-antiparticle (creates new particle after annihilation), the virtual ones does not produce anything, since they are created from nowhere, which the...

Astronomers Create First Realistic Virtual Universe http://www.cfa.harvard.edu/news/2014-10 http://www.illustris-project.org/

Trouble understanding "Virtual cache" Hi, I'm having trouble understanding what virtual cache actually means. I understand that to get a cache hit (physical cache) you index to the cache set and compare all the tags in that set with the tag in the cache address you are looking for. I...

Recently, I was reading about Hawking Radiation in A Brief History of Time. It says that at no point can all the fields be zero and so there's nothing like empty space(quantum fluctuation etc.). Now, the reason mentioned was that virtual(force-carrier) particles cannot have both a precise rate...

As we know that in classical world we have a clear arrow of time which points towards future..We can see glass falling from table and break but not the opposite in our world and whole universe... If we watch a film of glass being broken and that film is run in both direction we can easily...

I read this on a website called Physics for Idiots "If an electron gets near another electron it emits a virtual photon which is absorbed by the second electron and let's it know it need to move away." If a virtual photon is absorbed, doesn't than make it real, and so break conservation...

Homework Statement I want to calculate the horizontal deflections at joints A and F (using Virtual Work method taught in Structural Engineering). Cross-Sectional Area (A) and E values are provided in the problem, and the attachment has all relevant dimensions and applied loads.Homework...

What should it be, {sin(ωt-\frac{k}{n}x)} or {sin(ωt-nkx)}? I am contemplating this with respect to the proper waveform in a medium, following specific rules, particularly when it comes to the dispersion relation and ultimately what this would mean in the context of the Lorentz transformations...

Stimulated virtual W+, W- when supernova core--> neutron star? Weak interactions allow supernova core electrons and protons to convert to neutrons and neutrinos allowing (under the right conditions) the formation of a neutron star? Large numbers virtual W+ and W-bosons are produced in a short...

I understand that one can measure a single photon being absorbed using a photomultiplier tube or CCD. Can one measure a single photon being emitted by monitoring the current through an LED or the recoil of an emitting ion? Is it therefore possible to detect the same photon both being...

Homework Statement See attachment. Homework Equations The Attempt at a Solution So I have shown that the plane wave sol'n satisfies the Klein-Gordon equation by subbing in and reducing the equation to: E^2 = p^2c^2 + m^2c^4 which reduces to: E = pc for an m = 0...

Homework Statement Two 3.0m wide mirrors meet at a corner. Taking the corner as the origin of the x/y axis, A red ball is placed at point A (-1m, -2m). 1) How many images are seen by an observer at point O? [Point O is not given coordinates, but looks to be at approximately (-3m, -3m)]...

Hello, I've been given a problem which is asking me to flesh out a calculation. The calculation is word for word like this; So I am being asked to work this out in detail, fill in all the steps. I thought that maybe I should try and show that the four momentum squared is not conserved at...

https://www.physicsforums.com/attachment.php?attachmentid=65907&stc=1&d=1390369310 I've been stuck on doing my revision on this problem. The equation of the virtual work, from what I deduce is [du = 0] -Pdx + mg dh However the answer given is...