query: Will any massless particle/object in the vacuum of space always travel at the speed of light?
positive_passages.docid: 17152
positive_passages.text: Do all massless particles (e.g. photon, graviton, gluon) necessarily have the same speed $c$?
negative_passages.docid: 91265
negative_passages.text: Has the speed of light changed over time?
negative_passages.docid: 8077
negative_passages.text: Photons in expanding space: how is energy conserved?
negative_passages.docid: 58404
negative_passages.text: Does vacuum (empty space) exist?
negative_passages.docid: 116871
negative_passages.text: Do photons take all paths or not?
negative_passages.docid: 3635
negative_passages.text: If a mass moves close to the speed of light, does it turn into a black hole?
negative_passages.docid: 139551
negative_passages.text: A Light is shone out the side window of a spaceship ( moving close to light speed ), will the light still travel at the speed of light in the B axis?
negative_passages.docid: 41041
negative_passages.text: Does a photon instantaneously gain $c$ speed when emitted from an electron?
negative_passages.docid: 38673
negative_passages.text: General relativity: For massless particles, is the momentum and velocity 4-vectors equal?
negative_passages.docid: 22118
negative_passages.text: If all motion is relative, how does light have a finite speed?
negative_passages.docid: 98389
negative_passages.text: Electromagnetic waves in vacuum
negative_passages.docid: 67327
negative_passages.text: Does this count as moving faster than light?
negative_passages.docid: 98593
negative_passages.text: Will speed of light in any denser medium will be same for all the inertial frame in that medium?
negative_passages.docid: 21144
negative_passages.text: Can gravity accelerate an object past the speed of light?
negative_passages.docid: 57773
negative_passages.text: About the speed of light and gravity
negative_passages.docid: 77372
negative_passages.text: "Speed" of Gravity and Speed of Light
negative_passages.docid: 85582
negative_passages.text: Why aren't all photons virtual particles even in the "vacuum" of empty space?