One of the oddities of general relativity is that the faster you go, the slower time moves. That's not much of an issue for most day-to-day things, but time slows to a crawl as you approach the speed of light. Things with mass can't get to c; they get heavier as they get faster, becoming massive as they get close to c and can't quite get that fast.
Photons have no mass. Thus, they don't have that issue and can hit the universal speed limit. This Ethan Siegel Starts With a Bang post elaborates on what that implies
When you move at the speed of light, this means the following:
- You absolutely cannot have a mass; if you did, you’d carry an infinite amount of energy at the speed of light. You must be massless.
- You will not experience any of your travels through space. All the distances along your direction of motion will be contracted down to a single point.
- And you will not experience the passage of time; your entire journey will appear to you to be instantaneous.
This has some interesting theological analogies. One of Jesus' nicknames is the Light; one of the least PC passages of the Bible, is "I am the Way, the Truth and the Light; no one comes to the Father but through me."
Light doesn't experience time. God introduced Himself to Moses as I Am (Yahweh in Hebrew, which gets morphed to Jehovah), and Jesus implied His divinity with the phrase "Before Abraham was, I Am."
A photon coming from 10,000 light years away could say that, it's older than written history (and chucks a young-earth timeline out the window, but bear with me) but has been in the now that whole time. Not to say that a photon is God, but the Light and mundane light is timeless.
Let me grab a passage that came just before the except above-
All our formulas to describe what it’s like for an observer gives us answers with infinities in them when it comes to asking what happens at the speed of light. But infinities don’t always mean physics is wrong; they often mean that physics does something unintuitive.
Theology is often equally unintuitive, as God works in a seemingly infinite scale from outside the cosmos. We also have paradoxical doctrine like the Trinity, where a single God has three persons but is still one or that Jesus was both human and divine in one package.
God's timelessness is one of those counter-intuitive concepts. However, science points to such a timelessness in the photon, the elemental unit of light, which is His nickname.