The discussion centers on the nature of mass and its relationship with the speed of light, specifically regarding massless objects like photons. It is established that an object with zero mass must travel at the speed of light, and concepts such as "invariant mass" and "relativistic mass" are clarified. The conversation highlights that while photons possess energy and thus have relativistic mass, their invariant mass remains zero. This distinction is crucial for understanding modern physics and relativity.
PREREQUISITESStudents of physics, educators, and anyone interested in the fundamental principles of mass and light in the context of relativity.
dulrich said:I am curious how you would "adjust" a body to change its mass at all. An object with zero mass must move at the speed of light or it wouldn't exist at all.
cubud said:I just wanted to know if objects without mass will always be traveling at the speed of light.
There is more than one sort of mass in relativity, e.g. "invariant mass" and "relativistic mass". Most physicists nowadays mean "invariant mass" when they say "mass". "Relativistic mass" is really just another name for "energy" (divided by c2) and the term is deprecated.FeDeX_LaTeX said:Why not faster? I was told that the photon traveled at the speed of light but it has a very, very small mass that is almost negligible (but still exists). So why wouldn't a smaller mass go faster?