三十年代以前,人们熟悉的基本粒子有质子、电子、光子和中子四种。1930年狄拉克预言了正电子的存在,他在求解自由电子波动方程时得到了两部分电子能量本征值,一部分从+m_0C~2到+∞,一部分从-m_0C~2到-∞,也就是说,电子除了有负能级外还有正能级。通常情况下所有的负能级都被电子填充,倘若电子吸收了足够的能量 Thirty years ago, people are familiar with the basic particles of protons, electrons, photons and neutron four. In 1930, Dirac prophesied the existence of positrons. When he solved the free wave equation, he got two eigenvalues ​​of electron energy, one from + m_0C ~ 2 to + ∞ and the other from -m_0C ~ 2 to -∞ In other words, electrons have positive energy levels in addition to negative ones. Normally all negative levels are electronically filled. If the electrons absorb enough energy