Please let me know what "this problem" refers to in the text

(5:15) When I was kid -- I was about eight years old. There was no pollution. In Delhi, we used to sleep out at night.

At school I was being just taught about Physics, and I was told that if there is something that exist, then it is measurable. If it is not measurable, it does not exist.

And at night I would lie out, looking at the unpolluted sky, as Delhi used to be at that time when I was a kid, and I used to stare at the universe and say, "How far does this universe go?" My father was a doctor. And I would think, "Daddy, how far does the universe go?" And he said, "Son, it goes on forever." So I said, "Please measure forever because in school they're teaching me that if I cannot measure it, it does not exist. It doesn't come into my frame of reference." So, how far does eternity go? What does forever mean? And I would lie there crying at night because my imagination could not touch creativity.

So what did I do? At that time, at the tender age of seven, I created a story. What was my story? And I don't know why, but I remember the story.

There was a woodcutter who's about to take his ax and chop a piece of wood, and the whole galaxy is one atom of that ax. And when that ax hits that piece of wood, that's when everything will destroy and the Big Bang will happen again. But all before that there was a woodcutter. And then when I would run out of that story, I would imagine that woodcutter's universe is one atom in the ax of another woodcutter.

So every time, I could tell my story again and again and get over this problem, and so I got over this problem. How did I do it? Tell a story. So what is a story? A story is our -- all of us -- we are the stories we tell ourselves.

In this universe, and this existence, where we live with this duality of whether we exist or not and who are we, the stories we tell ourselves are the stories that define the potentialities of our existence. We are the stories we tell ourselves.

Hi teachers!

I wonder what the underlined "this problem" refers to in the text.

Many thanks in advance!