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arXiv:astro-ph/0310808v2 paper by Lineweaver dated 13 Nov 2003 entitled "Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the universe" has a sentence in the second paragraph on page 4 that I find confusing.
The sentence is: "However, since the radius of the Hubble sphere increases with time, some photons that were initially in a superluminally receding region later find themselves in a subluminally receding region".
How can a photon that's in a region that's receding from us faster than c (in a universe where space is not only expanding but the rate of expansion is accelerating) find itself in a region that's traveling away from us at less than c?
The sentence preceding the one given above in Lineweaver's paper states: "Light that superluminally receding objects emit propagates towards us with a local peculiar velocity of c, but since the recession velocity at that distance is greater than c, the total velocity of the light is away from us".
Aren't these two sentences contradictory?
Frank
The sentence is: "However, since the radius of the Hubble sphere increases with time, some photons that were initially in a superluminally receding region later find themselves in a subluminally receding region".
How can a photon that's in a region that's receding from us faster than c (in a universe where space is not only expanding but the rate of expansion is accelerating) find itself in a region that's traveling away from us at less than c?
The sentence preceding the one given above in Lineweaver's paper states: "Light that superluminally receding objects emit propagates towards us with a local peculiar velocity of c, but since the recession velocity at that distance is greater than c, the total velocity of the light is away from us".
Aren't these two sentences contradictory?
Frank