Considering the fact that homo sapien and sub species history is about 1.5 or so million generations and recorded history is only about 20 thousand generations it's just a blink in time of a lifetime of each of us. There are physical phenomena that we deduce from our surroundings though. As we reach further into the past to collect data about facts with technological advances .........we still won't approach a meaningful understanding of our universe. Unless of course we somehow evolve . But then there won't be humans anymore. I think in the end all of this can't be fully resolved.

Because of expansion of the universe radiation frequency changes with time/distance from any radiation source. Doppler effect. Add diffusion .