They are called virtual particles in order to distinguish them from real particles，whose lifetimes are not constrained in the same way，and which can be detected.
它們被稱為"虛粒子"(virtual particle)，以便與實(shí)粒子(real particle)區(qū)分開來，而實(shí)粒子則不會(huì)以這種方式受到制約，并且其存在可得以測定。