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. F

    I Does Lattice QCD use virtual gluons?

    I'm given to understand that perturbation methods don't work in QCD because the coupling constant is too large. So they use supercomputers to calculate equations at various points on a lattice. Does this lattice method still take into account the virtual gluons that we might see in perturbation...
  2. P

    I The virtual photon can turn into a virtual electron positron?

    for example, when does an electron repel another electron with an electromagnetic disturbance?
  3. P

    I Electron and virtual electron-positron pair

    What is the probability that an electron will be annihilated by a virtual electron-positron pair?
  4. A

    B Virtual Particles and nothingness

    According to what I have read and watched (I am new to the subject) the empty space is actually full of temporary virtual particulars that spontaneously and continuously emerge from nowhere and then disappear from the nothingness again but from where comes so much energy for so much creation of...
  5. barryj

    Calculation about virtual image

    Homework Statement See my attached information Homework Equations On my attached solution The Attempt at a Solution see my attached sheet Please see my attached write up. I would appreciate a quick nudge as stated.
  6. E

    Certificate in creating virtual labs?

    Hello, I want to learn how to create virtual labs (html5, java and on) for physics education purposes. I could work on my own, but I am more interested in getting a solid background from experts. Is there any online course in which I could enroll? Thank you
  7. stockzahn

    Two operating systems or a virtual machine

    Dear all, my PC runs on Windows 10. In the near future I will have to perform some simulations with Open FOAM. I've already done that some years ago (Windows 7 and I used a virtual machine to be able to run Ubuntu/Open FOAM). My experiences were that the program was executed very slow (despite...
  8. BadgerBadger92

    B Are electrons virtual particles?

    Since electrons pop in and out of existence, are they virtual particles?
  9. Ravik Rocha

    Difference between real and virtual objects? (optics)

    I do know the difference between real and virtual images. I would like to know the difference between real and virtual objects. I need some examples. See this picture
  10. G

    The reality of photons (real vs virtual etc)

    I mean there is this division between virtual (in static situations) and real photons as the quanta of the EM field, but aren't all photons essentially "virtual" in the sense that they are purely made up by us in order to explain why we see discrete impacts of specific energy for a given EM...
  11. RosutoTakeshi

    Superman created virtual particles?

    Comic is Superman/Batman #80 Superman explains that virtual particles are always spontaneous generated And that he's using his heat vision to (excite) the vacuum in order to accelerate the process. He's generating more virtual particles So my question is, how much energy or heat did...
  12. sweet springs

    I Exploring QM in Virtual Gravity: Rindler and Rotating Systems

    I know quantum mechanics meeting with general relativity or quantum gravity is a difficult work to do.　In order to understand the problem more, I would like to know about QM in virtual gravity, e.g. Rindler system or rotating system. Is wave function in rotation system is fully derived, for...
  13. Malek

    B Speed of Light & Virtual Particles: Is There a Connection?

    Are there any relationships between the speed of light and the virtual particles in the vacuum? I mean that, Can I call it as a medium of propagation of a light beam?
  14. DrClaude

    How advanced is Google's virtual assistant technology?

    https://www.theguardian.com/technology/2018/may/08/google-duplex-assistant-phone-calls-robot-human Listen to the recordings. It is very troubling to hear.
  15. Pushoam

    Virtual work = 0 implies net torque = 0

    Homework Statement Homework Equations ## \vec \tau = \Sigma \vec r_i \times \vec F_i ## The Attempt at a Solution ## \vec \tau = \Sigma \vec r_i \times \vec F_i ## ## \delta W = \Sigma F_i \delta x_i ## Let's take our Cartesian coordinate system such that the axis of rotation...
  16. DGator86

    B Planck level effects of virtual particles

    Knowing that virtual particles appear and disappear at the Planck length, what is the effect of the annihilation on space-time where the particles used to be?
  17. Pushoam

    A Physical interpretation of virtual displacement

    From the above description of Virtual displacement, what I understood is: virtual displacement is another name for ## dx_i ## when dt = 0. I didn’t understand its physical interpretation. Could anyone please put some more light upon it?
  18. P

    I Virtual particles in Feynman diagrams

    In the first diagram above, if I understand it correctly, the photon turns into an electron positron pair and then back again to a photon. However, what exactly is happening in the second diagram at the bottom left hand corner? Is the electron being converted to an electron photon pair?
  19. dRic2

    Windows on Mac: Dual Boot or Virtual Desktop?

    I need windows on my mac to run some modeling programs, but I'm not sure whether go for dual boot or virtual desktop. I have all my programs already installed and I fear that dual boot + installing all the programs again will suck too much memory space... on the other hand I have never enjoyed...
  20. F

    I Two questions about "The Physics of Virtual Particles"

    Arnold Neumaier, I have 2 elementary questions about your article “The Physics of Virtual Particles”. 1. In the paragraph headed “States.” on p. 4, of 13, you talk about states of a physical system, with a mixed state specified by a Hermitian operator ρ of trace 1 acting on the Hilbert...
  21. J

    Principle of virtual work for continuous systems

    I always thought that the principle of virtual work (PVW) is valid for all structures, including continuous structures (like bars, beams, plates, etc.). However, in his book 'Fundamentals of Structural Mechanics', Hjelmstad states that the PVW is only valid for discrete systems with N particles...
  22. J

    I Are the energy fluctuations in space real or virtual?

    Heisenberg's uncertainty relation says: $$\Delta x \Delta p \ge \hbar$$ If we assume a massless quantum object then we have the relationship ##\Delta E = c\Delta p## so that the above uncertainty relationship becomes $$\Delta E \ge \frac{\hbar c}{\Delta x}.\tag{1}$$ I understand that if we have...
  23. F

    B What happens to virtual photons when an EMF is extinguished?

    Let's say I feed the same electrical signal into the opposed windings of a contrawound toroidal coil, and that this results in their individual electromagnetic fields cancelling to "zero". Can someone explain what in turn happens to the virtual photons associated with those canceled fields? For...
  24. Souhardya Nandi

    I Exploring the Distinction Between Virtual and Real Particles in String Theory

    I am reading a bit about them. However, I feel that there is not much difference between them except for the life span. Can you please help me understand the distinction ? Can this be explained on basis of string theory ? Please elaborate.
  25. Mcbleak

    B Expanding space time and Virtual particles

    If space time (the universe) is infinitely expanding what happens when it rips? Have we observed Virtual particles in an area and counted them? Does the expansion of space time affect the amount of Virtual particles in a particular area? Is it theoretically possible to expand space time to a...
  26. F

    Why is my virtual judge solution giving me wrong answers?

    << Mentor Note -- Posts edited to add code tags for better readability >> Hello everyone- The vjudge problem link is: http://www.lightoj.com/volume_showproblem.php?problem=1006 My solution is: #include <iostream> using namespace std; long long int arr[10001]; long long int a,b,c,d,e,f...
  27. F

    I Does the path Integral contain virtual particles?

    So Feynman's path integral considers every possible path that a particle could take from start to end. In that process, there would be a path which contains a segment from, say, A to B at time t. But there could also be a path with a segment from B to A at that same time, t. If so, would this...
  28. S

    I HUD; virtual image at infinity

    Hi, I am trying to create an HUD display - basically create a virtual image at infinity and look at it. I have two plano-convex lenses; the distance between them is the sum of their focal lengths; my object is therefore imaged at infinity. Here is the schematics that I'm pretty much trying to...
  29. S

    B Exploring the Existence and Energy of Virtual Particles in Quantum Mechanics

    Hello everyone, I am here today with a doubt, I first apologize for my ignorance on the subject, but come on, the uncertainty principle predicts that in the "vacuum" there are virtual particle that cancels out constantly, but my question is: which is the amount of energy that exists in this...
  30. T

    A Difference between virtual displacement and differential?

    What exactly is the difference between a virtual displacement and a differential displacement? It seems like they are really the same thing if by differential we assume we are talking about a distance whose magnitude approaches zero.
  31. Marrrrrrr

    A Virtual Fermions and Pauli Principle

    Hi guys, Do virtual particles, when they are fermions, obey Pauli exclusion principle as real fermions do? More specifically, what I am wondering is the following: Fermion fields would have some energy at every point in spacetime due to the uncertainty principle. Now, is it possible for the...
  32. B

    I Probability of creation of virtual particles

    Is it correct to assume that all known particles may be created as virtual particles in the vacuum? If so, is there a higher probability of a particular particle being produced than say some other particle type. For example, is an electron more likely to be created as a virtual particle than a...
  33. teroenza

    Virtual Ground Voltage Reference

    I'm building an Arduino voltage logger that includes an op-amp (OP27G) as a buffer on the input. Since I'd like to be able to measure voltages all the way down to zero, I want to power the amp with a bipolar supply. My initial thought was to build the rail-splitter below so I wouldn't have to...
  34. C

    Virtual work and D'alembert's principle

    I can't for the life of me figure out what virtual work or D'alemberts principle mean and what the intuition behind them is. As far as I'm concerned D'alemberts principle is just a restatement of Newton's second law but considering the work instead of just the forces. What am I missing? I'm...
  35. O

    B Why don't emission/loss of virtual photons lower a charge's energy?

    Hello all, I came to know that electric(electromagnetic in general) force between charge particles is mediated by photons. At first I just wondered what are photons doing here? I mean till what I know is that photons bundels of energy for em radiation and that they are massless but have...
  36. G

    Lens engineering for virtual reality

    What type of lens/prism would be needed to allow a image sensor to see 180 degrees, so the sensor could see a hemisphere. It doesn't matter if the input is distorted. I thought that a glass pyramid with a square base might work.
  37. izMuted

    How do I know if the image is real or virtual?

    Homework Statement I know that the object distance is 15 using the equation m = - (v/u) (+ or - depending on real / virtual) 2 = (+ or -) 30/u u = 15 However how do I know if the image is real or virtual? Homework Equations m = - (v/u) The Attempt at a Solution
  38. B

    Virtual Reality Headset Resolutions

    Before I tried VR headset. I thought it was just looking at screen closeup. but no.. it's more than that. I mean.. it's like you are really immersed in the surrounding and there is 3D effect I haven't foreseen. Most of those who haven't tried it wouldn't appreciate the experience. To those who...
  39. Pushoam

    Calculating force between capactor plates using virtual work

    Homework Statement Use “virtual work” to calculate the attractive force between conductors in the parallel plate capacitor (area A, separation z). That is, use conservation of energy to determine how much work must be done to move one plate by an infinitesimal amount, and then use the value of...
  40. C

    Ray diagram diverging lens both object and image virtual

    Homework Statement Draw the ray diagram of the case of a diverging lens where both object and image are virtual, that is ##f<0## , ##p<0## with ##p<f## Homework EquationsThe Attempt at a Solution I did not find this particular case of ray diagram in any textbook so I would like to know where...
  41. D

    I Build my own virtual wind tunnel

    I want to build a computer simulated wind tunnel. I have experience building physics simulators. I undersand that there are already some existing free wind tunnel simulators out there, but do they work at supersonic speeds? I want to predict the drag coefficient of various rockets and bullets at...
  42. SlowThinker

    B Brownian motion from virtual photons?

    This a really simple question: If I have, say, 2 ions close to one another, and measure their repulsion very precisely, is the force constant, or is it a series of little pushes caused by individual virtual photons? I know there are many misunderstandings about virtual particles, but I'm not...
  43. Sophrosyne

    I Why can't we detect virtual photons?

    I have heard a virtual phton as used in QED defined as being forced carriers between two fermions which last for very short periods of time. A couple of questions about this: 1) how do we know these are photons and not some other force carrier if we cannot detect them directly? 2) can...
  44. O

    Why does the Principle of Virtual Work work without higher math?

    The last chapter of most introductory textbooks on STATICS introduces VIRTUAL WORK. It is rarely taught (I studied the syllabi of colleagues). I understand the Principle of Virtual Work, having researched and studied the Calculus of Variations, Hamilton's Principle, the Lagrangian and related...
  45. S

    Is the idea of negative absolute temperature analogous to a virtual image?

    Is the idea of negative absolute temperature analogous to a virtual image in geometrical optics? I was reading this article about such a negative temperature: http://www.livescience.com/25959-atoms-colder-than-absolute-zero.html It seems to me that since temperature is defined by its...
  46. J

    I Virtual Particles and Energy Scales

    Just a basic question which I will ask through an example: An electron and positron can scatter by annihilating to form either a virtual Z or virtual photon, either of which can then pair produce to give an electron/positron pair (amongst an infinity of other processes whose contributions need...
  47. W

    Networking Virtual Machines: Best Practices

    Hi just curious, Are there standard methods for putting several Virtual Machines in a network?
  48. S

    Virtual image size/distance in an OAP mirror

    These seems like an easy question, but I have found nothing online: Does the size and distance of the virtual image produced by an off-axis parabolic mirror vary as a function of the off-axis angle, or will it be the same as the parent parabola? Specifically, I am trying to create a simple...
  49. J

    I What is the Waveform of Virtual Photons?

    My understanding is that the wavelength or frequency of an individual photon cannot be reliably measured. For example, if a beam of monochromatic light is filtered so that only one photon at a time enters a spectroscope, each photon may land anywhere on the screen. Only when a statistically...
  50. M

    I Virtual Particles: Speed & Impact on Rocket

    Hi, quantum fluctuations enable virtual particles in space. If a rocket travels through space, these particles (real ones of antiparticle-particle pairs) could impact it. Is the effect of an impact dependent of relative speed of such particle and the rocket? For example rocket could be warmed...
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