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.

View More On Wikipedia.org
Recent contents Top users
  1. C

    Understanding Virtual Particles and their Connection to Zero Point Energy

    can anybody explain to me virtual particles and how they related to the zero point energy?:confused:
  2. S

    Quantum superpostion, determinability, and existance of virtual particles

    I thought this up as a result of a philosophical debate over existence and more specifically creation. I asked them to give an example of creation saying that what we usually see as creation/destruction is only change, a restructuring. (ie. table being destroyed is actually a release of energy...
  3. L

    Question on Virtual Crystal Approx.(VCA)

    Dear all, I am now intended to do some first-principle calculations on disordered system, where VCA is an effective method. However, as to practical implementation using different methods, say Plane-Wave Pseudopotential, FPLMTO, FPLAPW, it's a litter hard to get a clear picture about how to set...
  4. E

    Kinetic energy change in virtual photon exchange

    I understand (vaguely) how momentum is exchanged via virtual photons in electromagnetic interactions. But how do the changes in kinetic energy occur? For instance, a proton and electron are at rest separated by a distance x. The proton emits a virtual photon and recoils in the direction of...
  5. S

    Calculating Virtual Photon Energy between +q and -q Charges

    Charges of +q and -q are separated by a distance L. What would be a typical energy of a virtual photon they exchange?
  6. W

    Calculating Buffer Solution Volumes for pH 4.6 using Titration Virtual Lab

    I really need help. I am a teacher and can't seem to figure out this problem, although I know I did it once before. I have used a virtual lab and know that you need 71 ml of acetic acid and 29 ml of NaOH, but don't know how to calculate it. Can someone tell me? I know the concentration of H in...
  7. ?

    Virtual Particles - Is it True?

    i saw this, is it true? http://forums.govteen.com/showpost.php?p=2494738&postcount=23
  8. P

    Are gravitons virtual or real.

    Maybe this thread should not be here. Are gravitons virtual or real. I've read that they are bosons, but... Also, are they expected to have momentum, virtual or otherwise? Thanks
  9. K

    Casimir-Effect: Beyond Virtual Particles & Photons?

    I read in wikipedia that the Casimir-effect is a one-loop quantum electrodynamical effect. This seems to be wrong to me. I always thought that it is raised due to electromagnetic zero point oscillations. And this oscillations have nothing to do with virtual photons either virtual particles. So...
  10. J

    Virtual Photon Lifetime: Proton in Atom Nucleus

    QFT states that all forces are due to the exchange of virtual particles, I'm interested in photons and their role in the EM force. I was wondering what the maximum time allowed for existence of an exchange photon is when it's emmitted from a proton in the nucleus of an atom. I'm thinkin' that...
  11. G

    Creating Matter from Virtual Particles

    I remeber hearing somewhere that if you apply energy to virtual particles before they annhilate each other and separate them by doing so, then they won't annhilate each other, thus giving more matter into the universe than it already has. Doesn't this mean that matter can be created? Has their...
  12. Loren Booda

    Exploring the Possibility of a Virtual Era Before the Planck Time

    Was there an early epoch when all particles were virtual - perhaps before the Planck time?
  13. L

    Electrostatic force and virtual photon exchange

    Hello, although being graduated in physics (but not being an expert on QED) I find myself embarassed in trying to explain in very simple terms how the electrostatic force arise from the exchange of virtual photon. Especially when it comes to actually reduce all calculations to the expected...
  14. C

    How does the principle of virtual work apply to solving statics problems?

    what is the principle of virtual work. In what circumstances this can be used to solve statics problems?
  15. S

    Existence of Virtual Particles

    As I understand it, according to the Copenhagen interpretation of QM, nothing can be said to exist until it is observed. I have also read that it is impossible to observe virtual particles in an experiment. How is it then that virtual particles can be said to exist?
  16. *Kia*

    Why Isn't My PHP Script Running on a Virtual Host or Subdirectory?

    I have anice php script which works well, however it only works from document root and will only return a 404 error if I try to run it in either a subdirectory or on a virtual host..... Any ideas how to get this script to run from anywhere? btw it is called from a html form I am running...
  17. Pengwuino

    Virtual reality games in how long?

    Does anyone think they know how long until we have great virtual reality video games? Something where you can somehow experience the game fully and practically "be there" busting down a door or shooting up a buncha mafia gang people... Something where you can literally feel the game. I...
  18. G

    Virtual pair production - black holes

    hi, this is about particle antiparticle pairs being produced outside the event horizon of black hole. this is what i know about it: we know that a black hole has entropy. it therefore must have temperature and hence must radiate. however, a black hole is defined as a body which pulls in...
  19. J

    Calculating the Radius of Curvature of a Distant Tree's Virtual Image

    Hi; Could someone please help me with the following question: The image of a distant tree is virtual and very small when viewed in a curved mirror. The image appears to be 18.8 cm behind the mirror. What is its radius of curvature? (Use positive for concave and negative for convex). Would I...
  20. W

    Can virtual produce anti-gravity?

    Perhaps it is a stupid question, but really confuses me. In QFT, virtual particles can be produced from vacuum, say, (M,0,0,0) and (-M,0,0,0) In Einstein's theory, if we consider the (-M,0,0,0) virtual particle, make it's energy-momentum tensor and solve the Einstein equation, and take the...
  21. Chronos

    Virtual Observatory: Cruise the Heavens from Your Recliner

    Are you too lazy, or cheap, to buy a decent telescope, set it up and cruise the night sky? But would still like to cruise the heavens from the comfort of your recliner with a fresh cup of herbal tea in your non-clicker hand? Here is your chance: http://freeware.intrastar.net/planetarium.htm
  22. K

    Annihilation of virtual e-e+ pair

    I read a book and there it is written something as following: "By the lifetime of a virtual pair (e-e+) (that is given by the HUP) a virtual e- can remove with the distance s from the e+ that is given by: s=c*d(t) (d(t) from HUP)." My question: How can they annihilate if they are away at a...
  23. N

    Virtual mirror on the road on hot days. Why is that?

    While in a car on a hot day, I notice that far ahead of me is a mirror-like surface on the road. I can see the reflections in that virtual mirror too. The mirror shifts with your moving forwards. Can anyone give a simple explanation? Thanks.
  24. G

    So Has Virtual Particles Been Proven To Exist?

    Or is it just straight out of the equations? has it been detected?
  25. K

    QED: virtual photons -spin conservation?

    I'm talking of quantum electro dynamics where we try to explain the electromagnetic "force" with virtual photons. Now an electron can "send" a photon that has more energy then it self (this photon is virtual because it can only exist because of the HUP). But spin must always be conserved. But it...
  26. S

    Exploring the Possibilities of Virtual Time and Black Holes

    Today, I read a book which is written by Stephen Hawking. I have something don't understand. We all know that REAL TIME must go from the past to the future,but how about VIRTUAL TIME? The book says that Virtual Time can be increased or decreased in a three dimensional space. I wonder why...
  27. C

    Quantum Foam and Virtual Particles

    I have read a bit about quantum foam and the creation of virtual particles. I understand the basic concepts, but there is one question that bothers me though: can we think of the virtual particles as just being a 'concentration' of spacetime caused by the uncertainty principle inherent in the...
  28. K

    Are Virtual Photons Responsible For Real Photons?

    1) What is the nature of the electric field that comes from a single charge? Do virtual particles create this field? 2) What is the nature of the coulombic interaction between charges? (I know that like charges repel and opposite charges attract. But what is the nature of the...
  29. W

    Are virtual particles really there?

    As we know, when we do calculations in QFT, we write down the ampitude, and find that it can be explaind as Feynman diagrams, which is easier to work out. Then we use Feynman diagrams as a tool. Now the question is, is the propagator really exists in the small distance, i.e. the Feynman...
  30. R

    Hawking Radiation – Empty space virtual antiparticle-particle pairs

    In reviewing explanations on evaporating Black Holes using Hawking Radiation, based on how the black hole might treat Quantum “Vacuum particle pairs”. Although direct observation of Black Hole radiation has not been confirmed it implied that “Antiparticle – Particle creation, and self...
  31. S

    Understanding Virtual Particles: The Mystery of Annihilation and Energy

    [SOLVED] virtual particles If there is createn a virtual pair (anti particle A and its particle B) in vacuum what are they doing in their life time? Is A always at the same position like B or how can they annihilate? And if they annihilate, what's with the energy (does it disappear)? Has the...
  32. U

    Will Virtual Reality Fully Immerse Our Senses by 2009?

    Ok, so I'm reading this book "The Age of Spiritual Machines", which is basically a book making predictions about the future of computers assuming the operation of Moore's law. Anyways, at one point, the author states something like "Around the year 2009, humans will be able to fully emerge their...
  33. H

    Virtual Pairs and the Fate of the Universe

    I was thinking... virtual particle-antiparticle pairs created just inside the event horizon of the universe continuously adding mass to the universe at an ever increasing rate as the event horizon expands and accelerates... How does this effect the mass/topology of the universe and could this...
  34. B

    Is Time Dilation Just a Virtual Effect in Relativity?

    Say 2 observers are moving with a constant non-zero velocity with respect to one another. Each sees the others clock running slow but since they both know about relativity they know that the other is infact aging at the same rate as they are. They just observe otherwise. To the layman this begs...
  35. Tsu

    Are you ready for a virtual Thanksgiving feast?

    This is our first PF Pot Luck! I'm providing the turkey and some dressing! http://hosted.yourimg.com/04/329/13/Thanksgivingturkey4PF.jpg What are YOU bringing to the table? :biggrin:
  36. M

    Virtual Particles: Questions & Answers

    I've got a few questions about virtual particles here. If in a vacuum, the virtual particle come in a particle, anti-particle pair. What are these particles usually? Also, is it possible that these virtual particles exert a gravitational force on an object during its short existence?? And...
  37. G

    Do virtual particles exist in string theory?

    if so, what would they be? virtual strings? and do they react in the same way as what we thought point particles acted? if not, then how do black holes radiate energy in string theory? also, a quick question about black holes according to string theory. Is there more than one type of black...
  38. R

    Exploring Virtual Particles: Black Holes, Energy, and Creation/Annihilation

    Why can't a negative energy virtual particle escape from a black hole? Could two sets of virtual particles arise from the same point in space simultaneously? And would they have to annihilate simultaneously? And how does a rapidly oscillating gravitational field affect virtual particle...
  39. humanino

    The Art of Alibi: A Virtual World of Appearances

    I could hardly believe what I read. Maybe this is common, and everybody has his own. I just discovered. :eek: :eek: :eek: :eek: Alibi If you speak french, you can already use it. Otherwise, they say they will soon be available in english, and also for Monique :tongue: So the...
  40. J

    Virtual particles vs. speed of light

    Hejhej, There is a religious forum where I am posting in some evolution vs. creation threads. Creationists often believe that the world and everything else has not existed much longer then several thousands years. If you ask them how to explain that the light from stars millions of light...
  41. W

    Can protons emit-absorb virtual photons?

    Can protons emit-absorb "virtual" photons? Does a free single proton behave like a free electron in the sense that it emits and absorbs "vitrual" photons as it interacts with another free or bound proton? Are there any special conditions under which protons emit and absorb "virtual" photons?
  42. P

    What is the Colour of Virtual photons?

    I have read some 'popular' physics and I get the impression that Electrostatic Force is caused due to transfer of virtual photons. Do these have a particular energy for a particular charge? Then they should have a particular frequency . Then if we place the charges in mediums with...
  43. M

    Interacting virtual particles?

    static fields - quantum picture I am trying to understand quantum field theory & QED but i am having problems, because i don't find specific answer: What is the real quantum difference between electric and magnetic field? Maybe in spin of virtual photons (1, 0, -1)? But then what is...
  44. Clausius2

    MATLAB Out of Memory: Increasing Matlab's Virtual Memory

    I'm furious with Matlab. when I reach a 1*10.000 array or similar figures it says to me: "out of memory". Does anybody know how I can do larger the virtual memory dedicated to this programe?. I have a 40 GB and 500Mb RAM computer, so it would be enough for eating anything!.
  45. B

    Double slits and virtual photons

    A while ago I was reading David Deutsch's book "The Fabric of Reality". Deutsch proposes that the double slit experiment is explained by the presence of large numbers of virtual photons, which leave the source, hit the wall, travel through the slits, and interfere with each other, much the...
  46. A

    Virtual Particle Anihilation

    When a vritual particle pair anihilates, does the energy radiate away in the form of gamma rays, or is it simply used to "repay the debt" of whatever energy that was borrowed to create those particles in the first place? I would assume the latter, but I would like a confirmation on that. Thanks.
  47. M

    Virtual particle and event horizon

    Was wondering: In Hawkins's " Univers in a nutshell" book, he talks about the behavior ov virtual particle pairs around the event horizon of a black hole. My understanding is that one of the antiparticle of the pair can be absorbed by the black hole. This makes for the release of the particle (...
  48. M

    Virtual particule and event horizon

    Was wondering: In Hawkins's " Univers in a nutshell" book, he talks about the behavior ov virtual particule pairs around the event horizon of a black hole. My understanding is that one of the antiparticule of the pair can be absorbed by the black hole. This makes for the release of the...
  49. turbo

    Orientation of virtual particle pairs in local fields?

    Can the presence of gravitational, or electro-magnetic fields cause virtual particles to arise with a preferential physical orientation? Logically, the virtual particles should not emerge in a preferred orientation if they arise spontaneously, and can't be acted upon by local fields until...
  50. H

    Do virtual particles violate Conservation of Energy?

    We are all familiar with the Law of Conservation of Energy: Energy cannot be created nor destroyed In other words, the total energy in a closed system is constant. But if the above "axioms" are correct, how does it cope with the existence of virtual particles? In quantum physics, events are...
Back
Top