Virtual Definition and 547 Threads

The most recent PBS Spacetime video presented an idea I didn't really think about, that as we try to observe an electron by zooming in, the more see the effects of virtual particles that annihilate with the "original electron". This is a great way to visualise the electron and all but one...

My understanding is (was) that "virtual particles" is a computational concept used in perturbation calculations in QFT e.g. in Feynman diagrams. This understanding is in conflict with the following note in Quantum Field Theory for the Gifted Amateur by Tom Lancaster and Stephen J. Blundell: and...

Suppose I'm considering a system of N particles that are constrained in their possible motions and so there are less that 3N generalized coordinates. Suppose now I perform a virtual displacement on one particle, which due to some constraints might force some other particles to more virtually...

In this 2D figure below, I can place: a motor at O a motor at J gravity on each link I can use Hamilton's principle, modified to the principle of virtual work and I can compute the motion of the linkage system. I do not have to account for these force FOUR forces (in this planar problem)...

Hi there, this question has already been discussed in this forum, however I do not know how to proceed further and if my reasoning is correct. I start by imagining a downard displacement of the 1kg weight. As a consequence of this, block A moves upward and to the right. Also, block B moves...

I've heard virtual objects are used in cinema halls I'm not sure of what that means, can someone explain this to me please? And btw by virtual object i mean when diverging rays from real object passes through a convex lens, the rays will converging and if you'll place a plane mirror infront of...

(I do understand there are many ways to formulate the FE method, but I wish to understand this one.) I understand that Hamilton's Principle is just that: a principle ( a law the recapitulates the equations of motion) I also understand that the Principle of Virtual Work (PVW) is a reformulation...

(My multipart question is from a very naive perspective, so sorry if it is rife with misunderstandings. Please answer conceptually, with as few & as simple equations as possible. I think that all of the answers to these questions should be understandable to a high schooler, though maybe the...

Game on VM won't work. It did work before i re-created machine, but I don't remember what did i do to get game working. I'm using windows 10 64 bit on machine and host is the same. When i launch the game it's just black screen and music, when I tried to play in window mode it showed the window...

Does anyone know of any groups who discuss this from a scientific or even experimental standpoint? Yes I am talking about a Matrix type virtual world. I have many ideas and with the state of the world in the way it is, from my perspective - could perhaps be a very important thing to consider.

My understanding is that the repulsion between two electrons is mediated by the exchange of virtual photons – virtual meaning not lasting long enough to be detected. But suppose one of the electrons is in the sun and the other on Earth. There should still be a repulsion because the...

Recently I've read more about virtual particles and at first I tought that there were only doubts that virtual particles are not interpretable with the help of uncertainty principle. Furthermore it can't be used an an "excuse" for the temporary violation of the conservation of energy. Can...

Found a question on another website, I have the exact same question. Please help me Goldstein says : I do not understand how (2.34) shows that the virtual work done by forces of constraint is zero. How does the fact that "the same Hamilton's principle holds for both holonomic and...

Goldstein 3rd ed says "First consider holonomic constraints. When we derive Lagrange's equation from either Hamilton's or D'Alembert's principle, the holonomic constraint appear in the last step when the variations in the ##q_i## were considered independent of each other. However, the virtual...

A block slides on a frictionless wedge which rests on a smooth horizontal plane. There are two constraints in this system. One that the wedge can only move horizontally and another that the block must remain in contact with the wedge. We want to find the virtual displacements for the two block...

Are the typical energies of virtual particles lower than real particles?

Hello, I am about to create (should I say install?) a virtual machine (VM) on my Windows pc to experiment with Linux. My understanding is that a VM is a "software" (or is it more properly a file? Or is it an image? I guess an image is just a big file?) that is run/managed by a hypervisor...

I imagined the bar slipping along a virtual displacement, with the top and the bottom slipping by equal amounts. Since the planes are orthogonal, I took the components of these displacements: the lower end is displaced Lsinα in the direction of the right plane and by Lcosα in the direction of...

My understanding is that virtual particles don't really exist. However, they somehow come into existence under certain circumstances. For example, in the Casimir Effect the virtual particles on the outside of the plate now have the capacity to transfer momentum and kinetic energy to the...

Summary:: Require to determine the designated forces using principle of virtual work ( unit force method ) I have no idea how to determine the multispan beam using virtual work, if I start to analyse the subsidiary portion BC member, the Yc can be calculated and following by the Ma... it seems...

My insurance plan allows these, but I've never used one. I'm wondering if anyone has considered (or maybe already has) partaking in telehealth? If so, I have some questions: a.) Are there particular types of doctor's visits you would tend to use tele-visits for vs. in-person...

In Theoretical Minimum: Quantum mechanics, Leonard Susskind describes an electron in the higher energy spin state in a magnetic field radiates a photon of energy ##\hbarγ|B_0|## and flips into the lower energy spin state. I am wondering if this photon is related to the "virutal photon" that...

I have a spherical concave mirror with focal length of 65cm, radius of curvature of 130cm. I hold the mirror close to the eye at approximate 45 degrees and I reflect an object below it as shown in the image. The distance between the object and the mirror is 90cm, that is more than the focal...

Hi everyone! Can someone explain which are the differences between a physical node and a virtual one and which one is potentially better . I've been looking for information but I haven't found anything. Thank you a lot.

I am obsessed with the development of the Full Dive Virtual Reality (transporting your consciousness to a virtual world, such as Sword Art Online). I believe this technology may be available at around 200 to 300 years. How long do you think it will take us, if at all?

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≤...

Does a sort of virtual tidal effect exist inside an accelerating body (space ship) similar to the way the tidal effect is present while rest on a massive body? Or could an accurate enough 'thought experiment' measuring device figure out if it's in an accelerating ship or resting on a planet, by...

https://www.aapt.org/Conferences/SM2020/index.cfm I wasn't originally planning to attend the meeting in Grand Rapids. But when it went virtual, I submitted an abstract before the original abstract deadline in March. They extended the deadline for abstract submission to June 3. Unfortunately...

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?

https://www.aapt.org/Conferences/SM2020/ Hopefully, it will be free to register, like the recent APS Virtual April Meeting. In that APS meeting, you had to register to view the presentations, whether live or pre-recorded. Registrants could also watch a recording of a live session. During live...

Hi all! Like everyone else, our university physics department is prepping for online labs. We are utilizing great simulations from several sites, check them out below if you haven't already. We are able to rewrite many of our labs 1:1 conversion to online! Colorado PhETs...of course ...

If 1kg make a displacement of 1unit upward then A make a 1/2unit down because 1/sin 30.after that i have no idea what do I will really need help. Thanks!

Hi all, One more virtual particle question (sorry all!): for individuals who would take virtual particles as being 'real' (but unobservable), what is their understanding then of the content of the vacuum? For example, if I place a electron all by itself in the vacuum (thus making it no longer...

Hi all, - an initial apology - there are a large number of threads on virtual particles on the site, and I apologize for adding another one. I had two questions - on a related note, the guidance provided by @A. Neumaier's FAW on virtual particles has been highly valuable for a novice . 1) Upon...

Hi, The following is not a homework question. My question is: My answer is: Total pages required = 2^32/2^7 = 2^25 pages Thus page table has 2^25 entries PM = 2^16 Total page frames in PM = 2^16/2^ 7= 9 page frames Somebody please guide me what is the correct solution for the above. Zulfi.

I watched a Youtube! video on black holes, and it said that black holes evaporate via Hawking radiation. If I understood the video correctly a virtual particle can pop into existence just outside the event horizon, and that one of the resulting pair can subsequently fall back into the black hole...

Hi all, Just a clarification question as I'm learning. It's possible to have Feynman diagrams where the internal lines (virtual particles) are in fact on shell. 'On shell' would imply 'observable,' (maybe?) but as noted in @A. Neumaier's great FAQ, only sets of Feynman diagrams have predictive...

In quantum electrodynamics, the energy exchange between two charged particles is called a virtual photon, allowing the exchange of quanta of energy between the two charged particles. But these are not the traditional photons of electromagnetic waves. They apparently just arise from the equations...

I am searching for anything on quantum fluctuations and virtual bosons for someone who is a serious but amateur physicist ie. I have completed undergrad physics/math and some graduate level math at university. I am having a hard time finding anything that isn't beyond pop science. Not really...

Summary: Can a particle accelerator accelerate gaseous fuel? Does space-time differ for detonating ionized fuel moving near the speed of light within a magnetic field such as a particle accelerator?

Do virtual particles travel at the speed of light, or do they have 'virtual rest mass'?

Hello May I ask: "What is the guiding philosophy of the Principle of Virtual Work?" I do understand it an how to use it, in classical mechanics. (And I will openly admit that I do not entirely understand what I am looking for, or what I am asking.) But what is happening at this moment in...

Because massive gauge bosons have a finite half life, are they excluded from the (infinitely, asymptotically remote?) in and out states of QFT? Or, to put it another way, are they restricted to the internal legs of Feynman diagrams, i.e. to being virtual only? We can see W and Z tracks in...

I was talking to a physicist who said to me that virtual particles can have a mass of a constant times by i ,as in the root of -1. I have been thinking about this more and it intrigues me. I have done some research into this and can't find further details. If they have an imaginary mass does...

Hello! I am a bit confused about the distinction between virtual and real particles. For example a Z boson, which has a very short lifetime, in all experiments will decay to some other stable particles (i.e. it is detected through its decay). This means that it will always appear as a...

for once not a Hollywood ending. Looks like Blade Runner at first, the plot is not unfamiliar but the ending is.

Is it possible to get a real image of virtual objects, If so please explain with examples and some real life situations? Look at my assertion "rays will not pass through virtual objects so how it can form real image", is this possible, please help.

The first chapter in Goldstein's Classical Mechanics ends with 3 examples about how to apply Lagrange's eqs. to simple problems. The second example is about the Atwood's machine. The book says that the tension of the rope can be ignored, but I don't understand why. The two masses can move...

This is an inverting amplifier incorporating an ideal op-amp with infinite open loop gain. I have a simple question concerning the derivation of its gain (-R2/R1). The point I circled is at 0V (Virtual Earth) but then, if V+=V-, Shouldn't Vout=0 regardless of what R2 and R1 are?? What's wrong in...