负能量研究：内容、方法和意义

本文首先指出物理参数的正和负是自然界对称性机制之一，其次回顾了自由电子理论中的负能态；然后讨论了自然界存在负质量和负能量的可能性。1928年P．Dirac最先提出了负能概念，它已广泛应用于物理学的各个领域。本文仅讨论近年来的实验和理论进展。在现代物理学中通常认为真空应依照实际存在量子场的零点能而理解，例如把Casimir能（Ec）看作量子化的电磁场的真空能在提供边界时所造成的——当把双平行板介入到真空中，板间内能减小，能量的变化使Ec〈0，即得到负能量。负能量是量子物理学的重要概念之一，其时真空被看成折射率小于1（n〈1）的媒质。在Hawking理论中，实、虚粒子都可携带负能，不过这观点尚有待实验证明。另一方面，在人类实验室中制造负能量也是可能的，办法如利用Casimir效应，利用负群速，或利用超材料。最后，本文指出众多超光速效应与负能量相关，这对超光速研究提供了更深刻的理解。

The Contents,Methods and Meanings of Negative Energy Research

In this article, firstly we say that the positiveness and negativeness of physical parameters are one of symmetry in nature. Secondary, we review the conception of negative energy state in the theory of free electrons; and then we discuss the possibility of existence of negative mass and negative energy in nature. The concept of negative-energy was presented by P. Dirac in 1928. It is very general and finds applica- tions in various fields of physics. This review is limited to the progress on experiment and theory that has been achieved in last few years. In modern physics, the idea of vacuum is often invoked as decisive evidence that the zero-point energys of quantum fields are real. For example, the Casimir energy E, can be considered as the variation of the vacuum energy of quantized fields due to the presence of boundaries. When the vacuum inserted two plates, the inner energy decrease. The variation of energy makes E~ 〈0, it is negative energy. However, we say that the negative energy is one of the important concepts in quantum physics. In that idea, the vacuum is a medium of refraction index less than one （n〈 1）. And in Hawking＇s theory, the real particles or virtual particles can carry about the negative energy, but it still want the experimental ver- ification. In addition, it is possible to make the negative energy in the laboratory, the methods such as Casimir effect, negative group velocity, and meta-materials. Finally, the superluminal effects are related to the negative energy. This is a conclusion of scientists in several countries. They provide a deeper under- standing of the phenomenon of faster-than-light research.