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. Greg Bernhardt

    Virtual World Integration and Social Networking

    An interesting idea came up in my class last week about the future transportability of virtual world avatars into other virtual worlds. *For years this has been one of the elements of a utopian virtual future, where all avatars have property and free speech rights and they can all move back and...
  2. Ivan Seeking

    Digital Nation: Life on the Virtual Frontier

    I am watching this now and it looks pretty interesting. One thing that caught my attention was a segment about a Japanese school that teaches internet etiquette to young children. http://www.pbs.org/wgbh/pages/frontline/digitalnation/etc/synopsis.html Watch online...
  3. A

    Static Electric Fields / virtual photons / Ionization

    Hi Got a question, hoping someone can give a good explanation for. We all know that large static uniform electric fields have the potential to ionize. (Dielectric breakdown of Air - Static Electricity Shock). In the Quantum picture, why does this occur. Take for instance the photo...
  4. S

    Deriving Coulomb's Law: Exploring Virtual Photon Exchange Theory

    derive Coulombs law of electrostatic force by using virtual photon exchange theory of electrostatic field
  5. S

    Virtual particles and Einstein energy relation

    So, all I ever keep reading is that virtual particles don't HAVE to satisfy E2 = p2 + m2. Should it instead be that they don't satisfy the energy relation. Also, can someone show the general case mathematically how the energy relation is violated. If it's easier maybe a simple example of an...
  6. R

    Exploring the Existence of Virtual Particles: A Comprehensive Analysis

    i've been scrolling through the archives and can't get an answer if virtual particle exist or not or are real,I get different answers looking on websites.
  7. J

    What are space-like and time-like virtual photons?

    Hi, I'm trying to get my story straight about virtual photons. So far, my understanding of them is that they are the particles that mediate the electromagnetic interaction, and they only exist a short time due to the Heisenberg uncertainty principle meaning that they can't be directly observed...
  8. J

    Feynman QED, Permanent Magnets, and Virtual Photons

    I'm not making any statements here, only asking questions. When I take two permanent magnets and I feel the repulsive force between them, Feynman QED says it is the momentum of the virtual photons "pushing" the magnets apart? Experiments have been done, forcing some of these virtual...
  9. L

    Understanding Real and Virtual Images: A Guide for Beginners

    Im having such a hard time understanding what these types of images even are this is what I've read so far real images "rays from a point of the object meet at a point" im so confused? what? they meet at the principal focus when reflected?? can somone please dumb this down for me in the...
  10. R

    Mirror Optics- Measuring Virtual Image

    Recently, I asked my physics teacher how to measure the height of a virtual image behind a concave mirror. He said he wasn't exactly sure so he offered to give extra credit to anyone who could find information on how to do it. Is there anyone who can help?
  11. A

    Interactions between real and virtual particles?

    Hi folks, I have a question about virtual particles, and so far I haven't been able to find an answer. Do virtual particles ever annihilate with real particles? (Black hole evaporation aside) For example, let's say we have a (real) electron, floating in space, and a virtual...
  12. J

    Do Electrons Interact With Virtual Particles?

    Can electrons, or other real particles for that matter, interact with virtual particles? Do virtual particles ever come into existence in between the electron's energy levels of an atom? Is there actually a vacuum between electron energy levels of an atom or is this an abstract...
  13. M

    Are These Virtual Warm Fuzzy Slippers the Perfect Christmas Gift?

    Lisa, my virtual Christmas gift for you. I hope you don't have arachnophobia.
  14. M

    Virtual Machines: Do you have one ? Xen,VMware, Virtual Box

    Virtual Machines: Do you have one ? Xen,VMware, Virtual Box Hi ... all ...Do you have a virtual machine ? (XEN, VMware, VirtualBox, or any other ...) ... please give more info on how you are using it ? I''m trying to find out what are the different ways to use them ?... how are people...
  15. D

    Geometric Interpretation for Virtual Velocity

    Hello, I am having hard time giving a geometric interpretation for the virtual velocity in classical mechanics, defined as: \delta \dot{x} = \frac{d}{dt} \delta x where \delta is the virtual differential operator, and \delta \dot{x} denotes the virtual velocity of x. I think having a...
  16. P

    Virtual Particles: How can they be responsible for attractive forces?

    I don't really understand quantum physics, but I would really like to know because I'm going to study it next year. Can someone explain it to me in laymens terms, thanks.
  17. U

    Understanding the Principle of Virtual Ground in Op-Amps

    What is the principle of virtual ground? Please elaborate. Attempt: The input impedance of an op-amp is so high that virtually all input current is shunted to the feedback resistor when is works as interver. When noninverting input is grounded and internal resistance of op-amp is very high...
  18. P

    Real and virtual photons via neutral pion decay

    I wasn't sure whether this question should go in advanced or introductory physics but I decided to post here since it doesn't involve any complex maths. Homework Statement Part 1 Consider a neutral pion at rest. On the basis of conservation of energy and momentum alone, show that it is...
  19. W

    Virtual Particles: Real or Not?

    Virtual particles I'm confused. I have a degree in philosophy and physics is not my area of expertise. I have read about the subject so please don't give an answer fit for a 4th grader. What are virtual particles? Are they real or not? Are they some strange hybrid of reality and non-reality...
  20. N

    Energy conservation for virtual photon

    In introducing the concept of 'virtual photon',Halzen Martin writes (ch#1,P#7) "An ekectron emits a photon (the quantum of electromagnetic field) and as a result,recoils in order to conserve momentum.it is clearly impossible to conserve energy as well,so the emitted photon is definitely not a...
  21. A

    Can Virtual Particles in the Vacuum be Directly Detected?

    Why cannot virtual particles in the vacuum be directly detected? Experiments have shown the Casimir Effect that supports the idea of virtual particles does exist. But can we also detect the presence of virtual particles directly in the vacuum? The most common virtual particle to form is photon...
  22. djeitnstine

    Project Natal: Milo - E3 Stage Demo, Virtual Human

    This probably belongs in the General discussion area but I'd really like to discuss the computer science aspect of this. The AI in this program seems quite amazing. I'm not sure what type of learning this AI has, would it be adaptive or preemptive... This seems like the pinnacle of modern day...
  23. S

    Virtual Particles: Disproving Energy Conservation?

    Do virtual particles disprove the law of conservation of energy? Are they really created out of thin air or does something cause them?
  24. Feeble Wonk

    Virtual Particle Density in Expanding Space Time

    Please have pity on a poor ignorant layperson struggling for understanding... and keep in mind that I am mathematically impotent. I am trying to wrap my mind around the concept of expanding space-time with regard to quantum foam. Could someone please explain whether the "density" of quantum...
  25. A

    Do virtual photons Doppler-shift?

    Just a casual thought I had, with no answer since I'm not well-versed in QFT: Given two point charges, the force between them is given by Coulomb's law, \frac{1}{r^2}. I know this is only fully accurate when the particles are stationary. What I'm wondering, is that since the force is mediated...
  26. A

    (Beam theory) Deriving Virtual Work

    Homework Statement Derive the equation used for calculating the deflection of a beam at some arbitrary point. Because I haven't seen anything like this on the web or in textbooks, I am asking for some feedback. Homework Equations v_{k} = \int\frac{\delta M(x)M(x)}{EI} dx The Attempt...
  27. S

    How Real Are Virtual Particles?

    How "Real" Are Virtual Particles? Are they a help to particle interaction or are they physically real? How come they are not observable to us? what i want to find out is if they are an artefact or not.I also know that there is a lot of debate to whether virtual particles exist in reality or not.
  28. M

    What is virtual energy level ?

    What is "virtual energy level"? What is "virtual energy level"?
  29. G

    Can Real Images Be Viewed Without a Screen?

    I have a question about lenses and mirrors and the above topic.. As I understand it, a real image is one that formed when all the light from one source is converged again at another point and our eyes see that light again spreading from the converged spot. So if you put a screen at the spot...
  30. C

    Detecting Virtual Photons & EM Force: A Particle Physics Quandary

    Hey all, I am an undergraduate taking a particle physics class and we just learned that the EM force was caused by charges "spitting" virtual photons back a forth. In like second grade we learned that the EM force was dependent on the two charges involved (keeping this simple) and the distance...
  31. I

    Calculating Distance from Mirror for Virtual Image Height of 1.145 cm

    Homework Statement An object whose height is 0.375 cm is at a distance of 10.5 cm from a spherical concave mirror. Its image is real and has a height of 1.145 cm. Calculate the radius of curvature of the mirror. Correct, computer gets: 1.58e+01 cm ACTUAL QUESTION How far from the...
  32. P

    Find the Best Virtual Chem Lab for General Chemistry Labs - Try It Now!"

    Hey guys, does anyone have a strong link for a Virtual Chem Lab for General Chemistry labs? It can be online or downloadable. Thanks
  33. J

    Virtual AP Physics Class (Advice Needed)

    Hello, I've lurked anonymously for quite a bit on these forums, and until now had no reason to register and ask a question. Background: high school senior with (otherwise) high GPA(3.9) and fairly good ACT score (31) seeking advice and consulting from experienced PF member. Now that...
  34. stevebd1

    Virtual Particles: Exploring Energy Mass & Conservation

    How exactly do virtual particles add to energy mass while still complying with the conservation of energy? For instance, sea quarks, (virtual quark, antiquark pairs) are suppose to contribute to the mass of a brayon. Do they exist for a fleeting moment below the Heisenberg limit by popping in...
  35. E

    Explore Second Life: A Virtual World by Linden Lab

    I thought this internet application created by http://lindenlab.com/" was interesting: http://en.wikipedia.org/wiki/Second_life http://secondlife.com/ It takes the idea of a video game to an extreme. Video games normally either capture some specific portion of real life (i.e. life...
  36. P

    How does the creation of virtual particles allow the universe to accelerate?

    Based on theories of an accelerating universe, how can the creation and annihilation of pairs of particles/anti-particles (virtual particles) generate energy in a vacuum (space) thus contribute to Eintstein's theory of a cosmological constant (positive pressure). And if the quantum...
  37. Moonbear

    Virtual Office Hours: Benefits & Challenges

    Have any of you ever tried virtual office hours? For example, using a forum or chat session instead of sitting around your office for an hour twiddling your thumbs waiting for nobody to show up? I'm asking because I'm trying it right now for one of my courses. I could not find an hour...
  38. B

    Why Can't Detected Particles Be Virtual?

    On the wikipedia page about virtual particles it says: "If a single particle is detected, then the consequences of its existence are prolonged to such a degree that it cannot be virtual." Could someone explain to me why this is true, ie why is it that if we detect a particle it cannot be...
  39. putongren

    Exploring Quantum Foam and Virtual Particles

    Hi I'm trying to learn more about Quantum Foam and naturally my curiosity led me to Wiki. In Wikipedia, it says that at such small scales (Planck length) the uncertainty principle allows particles and energy to briefly come into existence, and then annihilate, without violating conservation...
  40. J

    What is virtual work? And how does it apply to this question?

    Hi All! I am new on here so I hope you quality people can help me out:) I have this question and it asks me to solve it using Virtual Work? What is that and how do I apply it to this question: "A slender rod of length L is attached to a collar at B and rests on a portion of a circular...
  41. B

    Virtual particles and perturbation theory

    I have been told before that virtual particles are just an artefact of perturbation theory, that if we could solve interacting fields exactly we would have no need to talk about virtual particles at all. My question then is if virtual particles are just a mathematical tool to evaluate...
  42. T

    Particle or Virtual Particle: What's the Difference?

    what is the differace between a particle and a virtual particle?
  43. somasimple

    Virtual colors for atom representation?

    Hi there, I suppose there is a standard palette for atoms representation? i.e. white for hydrogen, red for oxygen? Is there a site or a link that provides such information?
  44. B

    Questions on Virtual Particles

    I have a few questions. Why is it that detection of a virtual particle would mean that it cannot be virtual? What is it exactly about the detection that destroys the virtual nature of a particle? I have read in several places that the idea of virtual particles is just an artefact of...
  45. M

    Witness GLAST Launch: Now on Virtual Institute of Astroparticle Physics

    The videorecord of GLAST launching is available now on the website of Virtual Institute of Astroparticle physics 1-Glast official video 2-Glast launch as seen from the beach http://www.cosmovia.org/:wink:
  46. GRB 080319B

    Virtual Particles: Explained in Layman's Terms

    http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html I am new to physics and have been struggling with the idea that forces are just "action at a distance" and that fields are invisible/incorporeal (can only be detected by the influence they exert) and permeate throughout all...
  47. U

    Exploring Properties of Virtual Photons in Positive/Negative Interactions

    I'm having a lot of difficulty finding info on the properties of virtual photons - things like their polarization when exchanged between positively and negatively charged particles. Feynman says, in his book QED: the strange thory of light and matter, at p. 120: Photons, it turns out...
  48. M

    Virtual particles stolen from the universe?

    Hey! Virtual particles appear and annihilate all over the universe. If a pair is created just on a black hole event horizon, the hole can take one particle and the other goes free - the hole has to give some energy in order for this to be real. Hawking, no? But - what if two small black...
  49. T

    Virtual Particle Interaction: Will Virtual Boson Leave Track?

    Suppose there's an interaction AB -> CD, that goes via a virtual W boson, my question is, will the virtual boson leaves a track in the detector even though it's virtual ?
  50. B

    Need a GRE Study Buddy? Join My Virtual Desk

    I posted this over the Academic/Advise forum. Reposting it here to cast a wider net. Hope the admins don't mind... Please be my GRE study buddy. I'm Chan from the Boston area. This is basically all you'll ever need to know about me because I'm trying a new approach -- you'll be my study...
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