Imagine a photon reaching the Hubble Space Telescope today had originally been emitted from a star in the early universe 13 billion years ago. Einstein’s Special Relativity tells us, traveling at the speed of light, that from the photon’s frame of reference, no time will have passed for the photon between the moment it was emitted from the star and the instant it was recorded by the Hubble telescope. In addition, at the speed of light, the length contraction (or Lorentz contraction) is said to shrink the distance between these two objects (the ancient star and the Hubble telescope) to zero. But herein lies the apparent paradox in two parts:
- In the early universe 13 billion years ago when the star first emitted the photon, there was no Hubble Telescope for the photon to instantaneously collide with from its frame of reference. In other words, how can the photon instantly collide with something which won't be invented for 13 billion years?
- Given the complete length contraction of all points in space to zero at the speed of light, how can a single photon ever be absorbed at any one particular point when, if all distance between points in the universe is zero from the photon’s frame of reference, the photon will hit each and every point throughout the universe simultaneously, not just one?
How to explain this apparent paradox in laymen’s terms.