To explain, I’m just a big old ignorant layman, but with other scientific fields I at least CONCEPTUALLY understand how they came to their findings.
Like if a Geologist tells me something about rocks I’m like: “Okay, idk how geology works, but I assume you did some kind of experiments involving rocks so you probably know what you’re talking about.”
Or if a neurologist tells me something about the human brain: “Okay, idk shit about neurology, but I assume you did some kind of brain scan or took some brain samples or did some kind of scientific experiment thingy to know this stuff about brains. I don’t know the exact details but I can at least abstractly understand the process by which you learned this thing you’re telling me now.”
Then I’ll see some news report about some finding a theoretical physicists made and it’ll be like: “The Universe is made of strings! And also the sun is a black hole! The universe is shaped like a doughnut!”
And my honky ass is just like: “How the fuck do you know that shit? What are you looking at? How did you figure that crap out?”
there are lots of observations about the universe which are interesting For example, magnets light and electricity seem to be interlinked by a set of relationships. Theoretical physics is about developing frameworks (sets of equations usually now) that match all experimental data and explain those relationships. Or answer puzzles/propose conditions under which experiments might illuminate them like why do magnets not have monopoles?
A lot of theoretical physics outside of the headlines is computational stuff, models for predicting material properties of things that don’t exist yet for example.
If we only had experimental physics, you’d be spending billions constantly re-engineering experiments to check results. Theoretical physics leading experimental physics which then informs theoretical physics is the dialiectic in action.
Much like social dialectics, theoretical physics is often sparked by noticing some oddity in existing experiments. Then that is investigated, explained, and a new model is invented and a new experiment devised to test the theory.