In some ways I'm a frustrated scientist or mathematician. The amount of times I've thought I'd go back to university and do theoretical physics because I like the big questions, but really I know now that that's not quite me. What's me is to do it in novels.
It's not even a question of whether the universe is meaningful or meaningless. It's in what way could it be meaningful, or in what way, if it was meaningful, could that be even more meaningless than normal meaninglessness?
I think predictability is built into any good novel in some way - you begin reading Anna Karenina and you know pretty much what's going to happen at the end. But that doesn't mean you know what's going to happen in the middle. For me, it's that sense of what happens in the middle that's important.
Everything I know I imagine everyone else knows as well. And then everything that everyone else knows I imagine they know on top of what I know, so I'm constantly anxious about what everyone else knows.
You can't do science in a novel, but you can do philosophy. Or, if you're really lucky, you can manage to pose a question in such a way that other people will take it on.