karsus
加入时间: 2008/05/14
文章: 15
经验值: 520
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作者：karsus 在 驴鸣镇 发贴, 来自 http://www.hjclub.org
virtual photon is indeed more of a concept theorized to help understand what "really" happens during an electromagnetic interaction process, in fact, virtual particle is such a useful and important concept that any quantum field theory (the basis for any genuine modern particle theory: QED, QCD, even string theory...) student will be asked to familiarize themselves with it if they really wanna proceed to the more interesting stuff such as Feynman diagram and/or renormalization. In this sense, any evidence for quantum field theory could be viewed as indirect evidence for the concept of virtual particle.. 
ps: granted, Casimir effect is indeed not a very good example of virtual particles, as it could be explained away with the zero-point state of the quantized field (but here I beg to differ, because it indeed depends on your interpretation of the "quantum field"), so perhaps one may want to look to the Lamb shift or the fine structural constant for more direct supportive evidence for virtual particle 
pss: Now i just remember, the concept of virtual particle has already been applied in cosmology... the famous Hawking evaporation: You think Black Hole can absorb everything that comes near it? NO!!! a pair of virtual particles can be born near the even horizon of a black hole. One might be dragged into the black hole, its energy becoming negative; then in order to maintain the law of conservation of energy, the other virtual particle has to run away from black hole, thus becoming real. The overall effect would seem to be the black hole is radiating particles (well. mostly photons "virtual" turned real ), and again, not a lot of direct evidences yet, but the basis for explanation is virtual particle... voila 
pssss: sorry for the English input, perhaps I will put up Chinese tomorrow...
作者：karsus 在 驴鸣镇 发贴, 来自 http://www.hjclub.org |
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小结"虚光子"----与"科学哲学"关于科学的判别问题有关.
