query: are photons are being exceptional in case of mass?
positive_passages.docid: 81880
positive_passages.text: How can a photon have no mass and still travel at the speed of light?
negative_passages.docid: 141866
negative_passages.text: The lightest photon ever detected
negative_passages.docid: 76255
negative_passages.text: Does a gluon have mass or not?
negative_passages.docid: 119639
negative_passages.text: Do photons bend spacetime or not?
negative_passages.docid: 30745
negative_passages.text: Why can't photons have a mass?
negative_passages.docid: 148218
negative_passages.text: How precise must the energies match for absorption of photons?
negative_passages.docid: 20037
negative_passages.text: Do photons have acceleration?
negative_passages.docid: 81503
negative_passages.text: Do photons truly exist in a physical sense or are they just a useful concept like $i = \sqrt{-1}$?
negative_passages.docid: 13563
negative_passages.text: What really causes light/photons to appear slower in media?
negative_passages.docid: 14036
negative_passages.text: What is so special about speed of light in vacuum?
negative_passages.docid: 72372
negative_passages.text: Maximum wavelength of a photon/electromagnetic radiation?
negative_passages.docid: 86156
negative_passages.text: Do photons have a duration?
negative_passages.docid: 85582
negative_passages.text: Why aren't all photons virtual particles even in the "vacuum" of empty space?
negative_passages.docid: 112965
negative_passages.text: Are virtual particles limited by the speed of light?
negative_passages.docid: 69983
negative_passages.text: Photon energy - momentum in matter
negative_passages.docid: 38865
negative_passages.text: How can a Photon have a "frequency"?
negative_passages.docid: 12847
negative_passages.text: If photons have no mass, how can they have momentum?