Why this is important:
Given what we see in the cosmic microwave background, the first light we can detect after the inflation of the universe, structures can only grow so large within our current models. Yet this, and other similar discoveries, appear to be larger than our current models predict.
Kids open their mouths when their heads are upside down - great way to quickly investigate what exactly they're chewing on
I mean, most idioms are silly if you take them at face value.
To me, "easier said than done" is a response to an unrealistic idea that carries the meaning of "I don't think that'll work"/"that's too much"/"etc.
If I told a friend "hey let's make spaghetti for dinner" and they replied "easier said than done" I'd be like "...okay, you're technically correct, but I want spaghetti so I'm gonna do that anyways"
But if I told a friend "hey let's solve world hunger today" and they replied "easier said than done" I'd be like "yeah, I know...maybe we can go help out at a soup kitchen?"
Disclaimer: I'm not well versed in astrophysics.
Ok, so: you know how Earth is part of the solar system? And the solar system is part of a large collection of stars and planets called a galaxy?
Well, there's lots of galaxies out there! And scientists for a long time have been trying to figure out how they formed - how did all the stars get close to each other? Why aren't they just randomly drifting around?
Currently, everyone believes that there's this magic stuff called "dark matter" that pulled the stars together to make galaxies. Kinda like how magnets pull things close to them!
And because galaxies are so big it would take a long time to pull the stars close together! Which means young galaxies would look less bright because the stars aren't all close together yet, like they are with older galaxies.
So that's what everyone believes.
But we're getting pictures from a really strong telescope that's showing us that young galaxies are brighter than we expected! Which is weird and exciting because it means that young galaxies might have been pulled together faster than we used to think! And our old theories about galaxy creation might be wrong!
There's a theory that explains how galaxies could come together quickly, without dark matter, but it doesn't really fit with many other theories we have about how the world works, so lots of people are thinking really hard to figure out how they might fit together.
And that's what science is all about! Finding out new information that shows you that you were wrong in the past, and using that information to figure out new ways to act and think in the future!