Particles that travel at the speed of light, such as photons, have no mass, while massive particles like electrons can only approach but never reach light speed due to increasing mass requiring more energy for acceleration. The discussion touches on time dilation, where time slows for objects moving close to light speed, leading to scenarios like the twin paradox, where one twin ages slower than the other during space travel. There is skepticism about theories suggesting that traveling faster than light could allow for time travel or affect past events, as such claims lack physical evidence. The conversation also briefly mentions quantum entanglement, where particles can influence each other instantaneously, regardless of distance. Understanding these concepts often requires further study of relativity and related theories.
