1. For example, it should be massless since the range of gravity is infinite. 比如，由于引力的作用范围是无限的，那引力子应该是无质量的。
2. In general relativity theory, graviton is the massless tensor particle, which results in gravitation action in proportion to the energy. 在爱因斯坦引力理论下，引力子为零质量的张量粒子，它导致了粒子之间存在着正比于能量的引力作用。
3. Comparing with the perturbation results in the generic nonrotating BTZ (NBTZ) black hole background, we found that the massless BTZ hole contains only normal modes in the perturbations. 与不旋转的BTZ（NBTZ）黑洞背景下微扰结果相比较，我们发现无质量黑洞仅有正则模。
