What is Virtual: Definition and 565 Discussions

In computing, a virtual machine (VM) is the virtualization/emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination.
Virtual machines differ and are organized by their function, shown here:

System virtual machines (also termed full virtualization VMs) provide a substitute for a real machine. They provide functionality needed to execute entire operating systems. A hypervisor uses native execution to share and manage hardware, allowing for multiple environments which are isolated from one another, yet exist on the same physical machine. Modern hypervisors use hardware-assisted virtualization, virtualization-specific hardware, primarily from the host CPUs.
Process virtual machines are designed to execute computer programs in a platform-independent environment.Some virtual machine emulators, such as QEMU and video game console emulators, are designed to also emulate (or "virtually imitate") different system architectures thus allowing execution of software applications and operating systems written for another CPU or architecture. Operating-system-level virtualization allows the resources of a computer to be partitioned via the kernel. The terms are not universally interchangeable.

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  1. L

    Virtual Work in a Pulley System

    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. Quick aside: This is straight out of the Exercises for the Feynman Lectures on Physics, in...
  2. S

    Virtual Work & Quadcopter Torques: Exploring Rotational Dynamics

    Here is what we know from virtual work: $$ \delta W=\sum_{i=1}^N{\vec F_i\cdot\delta\vec r_{i}} $$ Where ##N## is the number of bodies in the system. I am considering a quadcopter, modeled as a rigid body so it is just one body and we have: $$ \delta W=\vec F\cdot\delta\vec r $$ My question...
  3. C

    Virtual work in finite plane bending of Euler-Bernoulli beam

    Please refer to the following image, which shows a portion of the deformed centerline of a beam in its equilibrium configuration with a uniformly distributed load. The stress resultants are the axial forces T, transverse shears Q, and bending moments M at sections 1 and 2, with the rotations...
  4. I

    Particles vs. Virtual Particles vs. Fields

    It's easy to find references which explain that the photon is the force carrying particle for the electromagnetic force (ie https://en.wikipedia.org/wiki/Force_carrier). Similarly there are force carrying particles for other forces, like W and Z bosons carry the weak force. This has always...
  5. J

    Why Does Virtual Work Seem Incorrect in This Statics Problem?

    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...
  6. A

    Can Virtual Particles Be Observed in Experiments?

    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...
  7. Ryan-Duddy

    Do Virtual Particles Cause The Wave Function To Collapse?

    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...
  8. debasish panda

    Why is D'Alembert's Principle stated in terms of virtual displacements?

    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??
  9. Prashan Shan

    Do virtual photons explain this phenomenon?

    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...
  10. Prashan Shan

    What are the different forms of Virtual Photons?

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

    Understanding Virtual Objects: Formation and Characteristics

    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...
  12. nuclearhead

    Can you answer this virtual photon paradox?

    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...
  13. G

    Question about Virtual Particles

    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...
  14. cpscdave

    Op-amp Circuit with virtual Ground

    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...
  15. S

    Can a real image be formed by a virtual image?

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

    Qm virtual particle force on wire, acrose the universe

    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
  17. M

    Virtual Solar System (formula for gravity in 3d)

    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...
  18. M

    What is the polarization of a virtual photon

    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
  19. B

    Understanding virtual particles

    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...
  20. O

    Virtual image and Virtual Object

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

    Virtual particles are just math (MWI and MUH)

    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...
  22. A

    Virtual particles coming into existence

    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...
  23. E

    Method of Joints, Virtual Load

    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...
  24. B

    Is Virtual Wave-Particle Duality a Misconception in Quantum Mechanics?

    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?
  25. ORF

    Mesonic effects in the nuclear structure

    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...
  26. D

    Virtual work (internal = external)

    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)...
  27. MattRob

    Black Hole Hawking Radiation: Frame-Dependent Virtual Particles

    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...
  28. N

    Principle of Virtual Work and static equilibrium

    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...
  29. A

    A problem about virtual work principle

    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...
  30. A

    A problem about virtual work principle for continuous system

    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...
  31. S

    How do virtual particles mediate?

    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...
  32. C

    Optics: Spherical Interface -- Real and Virtual Images

    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...
  33. JohnPrior3

    What are virtual particles and why do they have large implications?

    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.
  34. M

    Virtual displacement and D'Alembert's principle

    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?
  35. M

    Are shell electrons accompanied by virtual neutrinos?

    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...
  36. T

    Gravitational effect of virtual particles

    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?
  37. D

    Is a Virtual Photon Flux the Same as Ether?

    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...
  38. Greg Bernhardt

    What are Virtual Particles? A 10 Minute Introduction

    Continue reading...
  39. Islam Hassan

    Virtual Particles in Inter-Quark Space

    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...
  40. F

    How are virtual images formed?

    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...
  41. K

    Does virtual particle-antiparticle annihilation produce anything?

    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...
  42. Greg Bernhardt

    The first realistic virtual universe created

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

    Trouble understanding Virtual cache

    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...
  44. Y

    Virtual particles and the Uncertainity Principle

    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...
  45. us40

    Arrow of time and virtual reality

    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...
  46. A

    Virtual bosons and conservation of energy

    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...
  47. D

    Virtual Work Method on a Truss

    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...
  48. A

    Is Virtual Length Contraction Influenced by Changes in Refractive Index?

    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...
  49. Spinnor

    Stimulated virtual W+, W- when supernova core-> neutron star?

    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...
  50. J

    If a photon's emission is detected is it real or virtual?

    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...
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