eli5 If matter cannot be destroyed or created, how does space constantly expand?

Question

Maybe I’m misinformed about this. But I was always told matter cannot be destroyed or created. But I have been told space is constantly expanding. Is this expansion of space not made up of “matter”? Where does it come from?

In: 282

Answer 1

I feel like this is missing as an ELI5: conservation of mass is mostly a chemistry idea. Mass is conserved in a CHEMICAL REACTION. Once you start getting into weird nuclear reactions and particle physics stuff, things get weird. But in our every day lives, mass IS conserved.