system
Given the following post, respond as if you're commenting on Reddit:
human
If cosmic microwave background radiation is traveling to us from a little after the Big Bang, at the speed of light, then how did we get here first?

Presumably the photons of the CMBR are moving faster than the matter we're made of. So shouldn't those photons have passed this point long before we got here?
gpt
The big bang wasn't an explosion in space at a point, away from which we're now flying. It was the expansion of *all* of space. For several hundred, thousand years after the initial singularity, the universe was too hot and dense for light to travel. Any time it was produced, it would immediately be absorbed by something nearby. But around 370,000 years after the initial singularity, the expansion caused the universe to cool sufficiently that neutral atoms were able to form. When that happened, light was emitted from *everywhere* in *all directions*. The light we're seeing as the CMB today comes from points that were so far away at that time that their light has taken 13+ billion years to reach us. Light from closer points passed us earlier, and light from more distant points will reach us eventually (except for some *really* distant points from which light may never reach us).