1 The speed of light and the fundamental of modern physics Yin Zhu Agriculture Department of Hubei Province, Wuhan, China waterzhu@163.com Abstract In recent, the faster-than-light, which can be exploited for faster-than-light communication, was measured and observed in different areas with different ways. It is generally thought that, if the faster-than-light is true, the special relativity shall be invalid. Here, by outlining the development of physics in the past 100 years, it is presented that a particle can be accelerated to a very large mass according to the Mass-velocity equation m=  0 √ଵ− 2 / 2 . Therefore, whether or not the faster-than-light is true, the role of the speed of light with Lorentz factor is significant. And, it is concluded that, the faster-than-light and the invariance of the speed of light are based on different fundamentals of physics respectively. In the special relativity, the high speed particle is only treated as a particle while in quantum physics a particle is always treated as the wave-particle duality, and the faster-than-light is based on the wave-particle duality. Key words: speed of light, faster-than-light, time dilation and length contraction PACS numbers: 03.30.+p, 03.65.-w, 03.65.Ud In recent, the faster-than-light was measured and observed in three areas: 1) The true nonlocality was measured in quantum physics (It is measured that the speed of the spooky action at a distance is larger than 10×10 4 c [1,2] ). And, it was presented that any finite speed v with c < v < ∞ predict ing correlations can be exploited for faster-than-light communication.[3] 2) It was measured that the speed of the force (interactive) electric field (Coulomb field) is larger than c by two groups with different ways.[4-7] And, 3) it was observed that the speed of gravitational force is faster than light and the energy and momentum can be transferred with this velocity.[8] It is well known that the invariance of the speed of light is a principle for Einstein’ s special relativity. If the faster-than-light is true, special relativity must be reconsidered. Here, the development of the whole physics in the past 100 years was outlined for understanding special relativity. It focuses on the experimentally confirmed and generally accepted results. The hypotheses and unaccepted generally results, such as the techyons[9] which was not