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Debra guest Debra 2011/07/09 04:47

Great haemmr of Thor, that is powerfully helpful!

社區高中的畜生 guest 社區高中的畜生 2021/07/13 14:14

Explanation

According to quantum field theory, the vacuum between interacting particles is not simply empty space. Rather, it contains short-lived virtual particle–antiparticle pairs (leptons or quarks and gluons). These short-lived pairs are called vacuum bubbles. It can be shown that they have no measurable impact on any process.[9][nb 1]

Virtual particle–antiparticle pairs can also occur as a photon propagates.[10] In this case, the effect on other processes is measurable. The one-loop contribution of a fermion–antifermion pair to the vacuum polarization is represented by the following diagram:

Vacuum polarization.svg

These particle–antiparticle pairs carry various kinds of charges, such as color charge if they are subject to QCD such as quarks or gluons, or the more familiar electromagnetic charge if they are electrically charged leptons or quarks, the most familiar charged lepton being the electron and since it is the lightest in mass, the most numerous due to the energy–time uncertainty principle as mentioned above; e.g., virtual electron–positron pairs. Such charged pairs act as an electric dipole. In the presence of an electric field, e.g., the electromagnetic field around an electron, these particle–antiparticle pairs reposition themselves, thus partially counteracting the field (a partial screening effect, a dielectric effect). The field therefore will be weaker than would be expected if the vacuum were completely empty. This reorientation of the short-lived particle–antiparticle pairs is referred to as vacuum polarization. 帥帥帥帥帥

社區高中的畜生 guest 社區高中的畜生 2021/07/13 14:14

我要出書《我在社區高中的日子》

conan504 guest conan504 2021/07/13 14:35

In the hydrogen spectrum
In 1947, Hans Bethe was the first to explain the Lamb shift in the hydrogen spectrum, and he thus laid the foundation for the modern development of quantum electrodynamics. Bethe was able to derive the Lamb shift by implementing the idea of mass renormalization, which allowed him to calculate the observed energy shift as the difference between the shift of a bound electron and the shift of a free electron. [7] The Lamb shift currently provides a measurement of the fine-structure constant α to better than one part in a million, allowing a precision test of quantum electrodynamics.

wing500 guest wing500 2021/07/13 14:48

https://en.wikipedia.org/wiki/Impedance_of_free_space

wing500 guest wing500 2021/07/13 14:48

https://en.wikipedia.org/wiki/Impedance_of_free_space

臺大物理柳橙汁 guest 臺大物理柳橙汁 2022/02/25 20:29

2022-02-24
劉玥晴
新臺幣
220
其它指定用途(台大物理系發展基金)