Virtual Definition and 547 Threads

Hi. I recently got my computer upgraded to have a 100G rather than 50G hard drive, and to have double RAM. However, I am having a different problem that is impacting my school. I take school online, and some of my courses are run off of disks. So I was working through one of the disks today...

Light travels slower in mediums like water than it does in the vacuum. Would it be even faster in the vacuum if the vacuum were "true" and there were no virtual particles popping into existence? Shouldn't light be slowed by them?

Homework Statement Assume that a high-energy nucleon is emitting a pion, i.e. the process N→N+π. Is the pion real or virtual or both? Motivate your answer with a calculation or a good argument. Homework Equations Virtual particles does not obey energy (and momentum) conservation. The...

At any given time, lots of them exist. I would expect this to produce a constant but rapidly changing gravitational force. How is this effect taken into account in cosmological theories?

Why are virtual photons and gravitons allowed to pass outwards through the event horizon of a black hole? Is it that it doesn't really make sense to assign a particular path to a virtual photon? This still isn't satisfying to me, as there is *no* path that allows a real photon to escape...

Hi everyone, I have some questions on the nature of virtual photons. Firstly, are they actually particles (in the sense that a normal photon is a particle), or are they just mathematical consequences...and if so, what is their nature? Secondly I have some questions still unanswered from a...

Hi, So, I'm confused about the difference between real and virtual images. Let's use a concave mirror for example. I understand that a real image is formed when the actual light rays reflect off the surface and converge to one point. A virtual image is formed when the rays don't themselves...

Are we sure about the existence of virtual particles?

Hello. Cant it be that the fabric of space-time continuum or space is transforming into the virtual particle and vice-versa?

A positive lens has a focal length of 12cm. An object is located a distance of 3 cm from the lens. How far is the lens from the image? Is the image real or virtual, erect or inverted? My attempt f = +12cm o = +3cm i =? 1/o + 1/I = 1/f 1/i = 1/f – 1/o = 1/12cm – 1/3cm = 1/12 – 4/12 =...

I often read that particle-pairs that are created in the vacuum consists of a particle and it´s antiparticle which both have an positive energy that is "borrowed" from spacetime according to Heisenbergs Uncertainty principle. But when it comes to Hawking radiation one often refers to one of...

Homework Statement A transparent photographic slide is placed in front of a converging lens with a focal length of 2.44 cm. The lens forms an image of the slide 13.2 cm from the slide. How far is the lens from the slide if the image is virtual? nearer possible distance = Homework...

Homework Statement Im having real trouble with drawing diagrams for virtual work. Can someone please, please help me! We were asked, in the diagram i posted, to find 1)vertical reaction at F, 2) all reactions at A, 3) bending moment and shear force at B using virtual work. i think i...

Quarks are smaller then electrons? I read that when a electron moves from a higher energy level orbit to a lower energy level orbit it emits a "real" quark... So are other quarks virtual?

I'm a novice here..but in virtual neural networks, does adding more virtual neurons improve the performance of the network in terms of recognizing patterns? Has this been experimentally verified anywhere? Can you then make an analogy that the same would happen in a biological neural network? Or...

You guys are smart and give good replies so i thought i would run this by you folks. Theoretically communism is the best for of government we have thus far, in praksis however that changes dramatically. Democracy is the current leader when it comes to ruling the masses... but is it not time...

Has anyone seen the software/demos for this project made by the U.Iowa?It looks pretty sweet. edit: you it would've helped if i posted the link also. http://www.digital-humans.org/santos/SantosPhotos.htm http://www.digital-humans.org/main.htm

I was just reading the Feynman Lectures on Physics when Feynman discussed virtual work. Unfortunately, I found his explanation somewhat confusing. The following are the three examples Feynman uses in order to illustrate the principle of virtual work. 1. 2. 3. I'm trying to...

1. The radius of Earth is 6.40 x 10³ km. The moon is about 3.84 x 10^5 km away from Earth and has a diameter of 3475 km. The Pacific Ocean surface, which can be considered a convex mirror, forms a virtual image of the moon. What is the diameter of that image?2. 1/p + 1/q = 1/f M = h'/h = -q/p...

what the term "virtual particles" referred to I wanted to know what the term "virtual particles" referred to. I found many "descriptions" of them on webpages. Fine. Then I went to the index of many advanced QM books, and the term "virtual" doesn't really show up as prominently as I thought...

Hi, I am writing a visual basic program and used MSComm for testing communication ports of PC. It is working well. At company, we have a game machine using two standard ports (com1 and com2 which can use MSComm to test) and virtual ports (com3 and com4). Of course, the program cannot test...

Sad i know but it is just a thought that, the ratio of real to virtual particles that are present at anyone time may have some outcome for QG, if anyone could even calculate such a thing.

we used a concave mirror and a candle for an experiment when the candle wa placed between the vertex and the focus of the mirror (f=12.7cm) a virtual image appeared behind the mirror. We measure the image distance approximately by pointing a finger towards where the image might be and got...

magnetic field is made of photons? i've been researching photons and i discovered on http://http://van.physics.uiuc.edu/qa/listing.php?id=414" and http://en.wikipedia.org/wiki/Photon" both resources state that all mangetic fields are made of photons. soooooo, this brings up a lot of...

How can one readily determine that the reality one experiences is real, not virtual - perhaps through Turing machine logic?

i know that virtual particles are a result of the uncertainty principle and that most of the time they are annihilated but i also think i read that sometimes they come into being when they receive an energy boost? I am thinking maybe an errant photon? also I've read about velocities of...

Perhaps someone can explain virtual particles. My intuitive notion of them is that particles come in and out of existence to communicate to other particles how to behave and if you try to observe them they disappear. How is the Higgs mechanism responsible for particle masses? What is a Higgs...

Hi, I'm a newbi when it comes to physics, but i read something last night that made me wonder: I read that an electron can send out "virtual photons" that "goes back" to the electron if it doesn't find anything to interact with, my question is now, when are these photons sent out? Is there...

In the "Beyond the Standard Model" forum there is a thread entitled "What causes gravity?" https://www.physicsforums.com/showthread.php?t=123380 In the discussion Yogi writes: What is the thinking among most physicists today on this issue? Are virtual particles considered certainly...

There's a lot of talk about "virtual particles" and of energy conservation within a normal perturbative approach to QM. I'm struck by the fact that there are precious little concrete examples or illustrations or gedanken experiments to support all the arguments, which go around and around and...

Hi I was wondering if somebody could kindly tell me what the difference between a real and a virtual image is. The way I which I know them apart is that in a real image the light rays actually intersect, while a virtual image the light rays diverge , thus never actually intersect. Is this...

According to what I have read, virtual particles are those which are intermediate photons in interactions, which cannot be directly observed. If my understanding is correct that would mean that they consist of (in low order perturbation theory), (among other things) u and t channel photons. But...

What is the Virtuality for a virtual photon (Q^2). How's it defined? What is the virtual photon's frequency then? Any relations between them? Thanks. :!)

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

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...

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...

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...

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

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...

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

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

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...

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...

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...

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

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...

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

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?

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...

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...