When Virtual Becomes Real
Virtual Particles appear due to the Weisenberg Uncertainty Principle.
So if [tex]\Delta[/tex]t is prolonged or something like that, virtual particles become real. Am I right? 
Hi Kyoma! :smile:
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No, virtual particles are a mathematical device in the Dyson expansion in perturbation theory in quantum field theory, they have nothing to do with the uncertainty principle. :wink: (Even the mathematics does not give them any location or duration.) 
Re: When Virtual Becomes Real
Then how do virtual particles become real? :confused:

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They don't.

Re: When Virtual Becomes Real
Tiny Tim said: "virtual particles are a mathematical device". Do you understand what that means?

Re: When Virtual Becomes Real
Tiny Tim: Who has time for "Werner Heisenberg", when you can rock the "Weisenberg". From now on I subscribe to the WUT (anyway **** that nazi Heisenberg...).
Kyoma: At no time are virtual particle intended in math from the outset to be real or "BECOME" real, and if they did they wouldn't BE virtual particles! "What if a horse had black and white stripes and lived in Africa?..." It'd be a Zebra, not a horse, that's what. In the struggle to 'get' from point A to B in QFT, these little mathematical devices called "virtual particles" are useful in the endeavor, but have no more physical reality than the FOIL method becoming a fencing implement. The only time you could conceivably move in the "striped horse in africa" direction would be Hawking Radiation, but that's not a virtual particle except for meaningless period in the math. 
Re: When Virtual Becomes Real
I would not be too quick to dismiss the concept of "virtual" particles/photons.
For example, can the extension of magnetism in freespace make any sense whatsoever without the notion of virtual photons? No. That is just one example. Sure, with virtual particles/photons it's all mathematical, but maybe something IS there, transitory as it may be. 
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Re: When Virtual Becomes Real
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http://img.alibaba.com/img/imagerepo...web17_9052.jpg This to me, is the clear solution to problems in QFT... plus what if I drop the remote, am I supposed to haul *** to pick it up?! I NEED those calories... really I do. 
Re: When Virtual Becomes Real
I think that Kyoma is confusing virtual particles with things like W and Z bosons, which have more energy than conservation of energy would allow, but exist for a very short period of time. That is OK because of Heisenberg's uncertainty principle.

Re: When Virtual Becomes Real
There are virtual W and Z bosons, which mediate lowenergy weak interactions like nuclear beta decay, and real W and Z bosons, which can be produced in accelerators with enough energy. The difference is exactly like between virtual and real photons.

Re: When Virtual Becomes Real
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In wikipedia, it states that if a single virtual particle is detected, then the consequences of its existence are prolonged to such a degree that it cannot be virtual... I don't understand this. And then there's the Hawking Radiation... which apparently allows virtual particles to become real... 
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In physics, a virtual particle is a particle that exists for a limited time and space, introducing uncertainty in their energy and momentum due to the uncertainty principle. Because energy and momentum in quantum mechanics are time and space derivative operators, then due to Fourier transforms their spans are inversely proportional to time duration and position spans, respectively.…virtual particles exist only in the maths (and even in the maths they have no creation event, annihilation event, or duration, whether limited or otherwise). A "particle that exists for a limited time and space" is a real particle … that's what "real" means!! :rolleyes: If it exists because it has "borrowed enough energy", then the amount of energy it has borrowed is exactly the amount for a real particle (eg, if it's a "borrowedenergy" electron, it has the correct wikipedia restmass of an electron), and therefore cannot be a virtual particle (which can have any restmass, even according to wikipedia, see below :rolleyes:) … it can only be a real particle! (Actually, that's not completely correct … there are two types of virtual particle in the maths, those in the position representation, and those in the momentum representation … the first type do have the correct restmass, but they only obey conservation of 3momentum, not of 4momentum. 
Re: When Virtual Becomes Real
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Also I’m not familiar with Dyson expansion, so I hope this doesn’t become some stupid question =P 
Re: When Virtual Becomes Real
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In other words, I might talk about the tires of my car "biting" the surface of the road as a means of describing what happens vis a vis friction and the road, but the tires don't bite. You can talk about virtual photons between casimir plates or virtual pair creation at the event horizon of a BH, but it's just a MATHEMATICAL artifact used to describe an "inbetween" interaction current physics has no physical explanation for. 
Re: When Virtual Becomes Real
I’m sorry but, for me, the virtual particles seem as real as Higgs Boson, gluons or strings. A physical materialization of mathematic postulates that embody the best hypothesis to explain a certain observed physical phenomenon.
I understand what you mean, but it seems to me the real difference is what we account as real, being your real only the observed, described and experimentally documented. Maybe I’m extending incorrectly my notion of “real”, that is true =) 
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In fact, here's the feynman diagram: [img]http://wpcontent.answcdn.com/wikipedia/commons/thumb/1/1f/Feynmann_Diagram_Gluon_Radiation.svg/287pxFeynmann_Diagram_Gluon_Radiation.svg.png[/img0 SOMETHING happens between the annihilation of the real particles and the emission of the quarks and gluon, but what is only described by a mathematical formalism that has NOTHING to do with physical reality. Something with a physical reality (a force, the exchange of energy, etc) is described down to the point where we have to use "tricks" to fudge a bit to the next step. I recommend reading this: http://en.wikipedia.org/wiki/Static_...ticle_exchange Especially portions dealing with the Coulomb Force, and have this up while you do: http://en.wikipedia.org/wiki/Virtual_particles This isn't an issue of observed vs. unobserved, this is an issue of a bit of "filler" to do the job of something taking place according to the HUP which can't be described any other way, yet. SOMETHING is going on, yes, but there's no virtual photon there at least. 
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Also I read the meanlife of the W and Z bosons it's around 10E25 seconds so I guess they can't be directly detected , and were discovered by indirect means, can someone explain in lay terms how? Thanks 
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