Nope. Cast a ray out in some directions and it might travel to the infinite future, thanks to the metric expansion of space. https://en.wikipedia.org/wiki/Ol

Nope. Cast a ray out in some directions and it might travel to the infinite future, thanks to the metric expansion of space. https://en.wikipedia.org/wiki/Olbers%27_paradox https://en.wikipedia.org/wiki/Olbers%27_paradox Most photons emitted from within our solar system are liable to collide with dust or gas eventually, most likely in the interstellar medium of our galaxy. Only a tiny fraction will collide with stars in our galaxy. The rest of our galaxy cluster covers a small solid angle of the skies of any of the bodies in our solar system. Finally, the small minority of photons that escape our galaxy cluster without being absorbed are most likely to stretch to arbitrarily long wavelengths and vanish from practical physical detectability well before the infinite future. It is vanishingly unlikely for an individual photon to couple to a lightlike geodesic that intersects a star at more than a few billion light-years. For experts, there is some meat in §§1-2 of these lecture notes: http://www.tapir.caltech.edu/~chirata/ph217/lec02.pdf http://www.tapir.caltech.edu/~chirata/ph217/lec02.pdf