As a laser beam starts to diverge after a certain distance and has a divergence or diffraction angle which is largest for red light somebody could observe two laser sources distant 1m from each other being more distant because some beams due to diffraction are curved and can fall into the eyes at larger angle.

  • $\begingroup$ Diffraction does not apply to a spherical or plane wave. Distant galaxies should look bigger for a different reason, but this has not been observed: Is the universe a giant telescope? $\endgroup$ – safesphere Feb 16 '20 at 8:50
  • $\begingroup$ @safesphere If photons are radial to each other why uniform expansion of space should alter the angle between them? $\endgroup$ – Krešimir Bradvica Feb 16 '20 at 12:22
  • $\begingroup$ The farther you see the object today, the closer it was to you when this light was emitted. This effect should happen in theory, but has not been observed. So the geometry of spacetime may not be what we think it is. $\endgroup$ – safesphere Feb 16 '20 at 17:11

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