I Where do the early photons go?

[John Helly]

TL;DR Summary

In the first 10s after the planck time, I've read that photons came into existence. However, since the radius of the universe was 'relatively' (pun intended) small, where did they go?

Since photons travel at c, where did they travel to, or was the universe expanding at the speed of light (or faster)?

 

[Ibix]

The universe was full of hot dense plasma, so they mostly got absorbed. Once the temperature dropped enough (some hundreds of thousands of years later) for the plasma to recombine into atoms the matter became transparent, and photons emitted around that time did not get absorbed. They continue to fly through space, and form the Cosmic Microwave Background that we can detect today.

 

[phinds]

since the radius of the universe was 'relatively' (pun intended) small

Just so you're aware, that is NOT necessarily true. It is possible that the universe was infinite in extent from the beginning

 

[Orodruin]

… shortly put: if it is infinite today, it was infinite then. But with a smaller scale factor.