system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do we know what the universe looks like today when all the light we see is from millions or billions of years ago?

Shouldn't the universe we see be like a fun house mirror with everything distorted? in fact, shouldn't it be worse than that? Wouldn't it be like looking at a fun house mirror, but in addition to everything being in the wrong place, your head might be your current age and your feet look like they did when you were a baby? The Milky Way is 120,000 light-years across, and that's just one galaxy. Can we really extrapolate through billions of years to get an accurate picture of the universe now?

EDIT: Thanks to everyone for all the great answers!

I just want to say that I think it's legitimate to ask what the universe looks like "now," even with the lightspeed barrier. Saying that it "doesn't matter" or that there is no "real now" or that "now has no meaning" because the idea of "now" is defined by what information can reach us at the speed of light, I think is a cop-out answer.

If we ever discover warp drive, or wormholes, or whatever, then it certainly WILL matter. Plus, things we can't see presumably do still exist. I don't see how the lightspeed barrier affects this.

Lots of things — quantum computers, nuclear fusion, teleportation, artificial intelligence – are beyond our scientific capabilities now (and perhaps forever), but it's still worth thinking about.
gpt
The picture we have of the universe is a picture of the past universe.  The reality is that what the universe is like **now** is irrelevant, because we won't experience that in any menaingful way until the future when the light reaches us.

We can of course make predictions about where these galaxies/stars are **today** even though we're seeing them thousands or millions of years in the past.

The only "real" universe is the one we can observe, and that's the one that's limited by the speed of light.

**everything** is limited by the speed of light, even your kid's soccer game, but the difference doesn't really matter because it doesn't impact us.  The same thing applies to space.