Virtual Definition and 547 Threads

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.

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...

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...

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...

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...

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...

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...

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

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...

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...

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.

What is "virtual energy level"? What is "virtual energy level"?

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...

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...

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...

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

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...

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...

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...

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...

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...

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...

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...

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...

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...

what is the differace between a particle and a virtual particle?

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?

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...

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:

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...

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...

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...

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 ?

If we can see a virtual image, why can't we obtain it on a screen?

In reading Feynman's "Lectures on Physics", volume 2 I have a question and have included a scan of a small section from the book. Feynman was a big fan of using the Principle of Virtual Work, but his explanation, as least insofar as how he used it is wanting, at least for me. The attached...

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 am attempting to create a virtual host here on my machine. I assume the place to do this is in the /etc/apache2/sites-enabled/000-default file. The file currently reads this: NameVirtualHost * <VirtualHost *> ServerAdmin webmaster@localhost DocumentRoot /var/www/ <Directory />...

Why forces are modeled as virtual particles in quantum mechanics and how virtual particles can transmit force between two real particles?

Folks, I have a question about virtual particles. I recently read in a Scientific American article which says that "virtual particles are indeed real particles. Quantum theory predicts that every particle spends some time as a combination of other particles in all possible ways. These...

A mentioning about virtual particle problem in my other thread just reminded me of some thoughts, which I now succeeded putting together. When calculating cross sections in QFT, we encounter terms like this \langle 0|a_{\textbf{k}'} a_{\textbf{p}'} a^{\dagger}_{\textbf{p}_1}...

I've often heard the argument that vacuum is full of virtual particle pairs that get created and annihilated, but in fact the ground state of the harmonic oscillator is orthogonal to all excitation states, so shouldn't the vacuum, when in ground state, actually be empty of all particles? What is...

How do you go about solving an indeterminate beam for various deflections by virtual work? I'm kind of at a loss right now and can't proceed on my homework. I've attached a picture showing the problem I'm confused on - I don't know how to go about modeling the virtual model so I can find the...

Securing your virtual space: by implementing timed logins. (a space-time formatted entry) (A) User: {name,schedule} (B) schedule: {window of opportunity* } (C) window of opportunity: {recurrance, theHOUR, theMINITE, duration} (4) recurrance: {any, yearly, quarterly, monthly...

I'm very happy that I found this forum, hello everyone. I'm studying Lagrangian Dynamics and I can't figure out how to find the generalized forces in a setup like this: ____ ____ | | ___ | | | b1 |===|___|===| b2 | |____| |____| --->x...

hi everyone, I am having a tough time convincing myself about the virtual short concept in opamps, As i understand from texts, on the application of a voltage on one of the input terminals of opamp, the voltage at the other input terminal is also forced to match the voltage on the first...

Can they appear inside a black hole? Can they appear between an electron and the nucleus? Inside a nucleus? Can two sets appear at exactly the same place? What prevents them from appearing exactly where other existing matter is?

I don't have a CD or DVD burner. Is there a virtual DVD program that will recognize .daa files?

I have a few questions concerning opamps. First what is the big deal about infinite common mode rejection? It seems to me by looking at the open-loop gain equation A(V2 – V1) = V0 it is obvious that when V2 = V1 the output is zero (common mode rejection). This may be where I am confused …...

With some additional software and hardware modifications, this guy creates a virtual reality display using his Wii. http://www.youtube.com/watch?v=Jd3-eiid-Uw&NR=1 Okay, so when are the new VR shooters cooming out? I'm tired of trying to peek around corners in vain. The technology for...

It seems to me that the physics is the same they are all due to the exchange of virtual photons between two particles