The strange planet of the rolling balls

In a distant galaxy, there is a planet where countless balls of every size live and roll. They communicate by transmitting vibrations via physical contact. That makes for a fairly quiet planet.
Bolla is an average-sized ball for her age, but unusually inquisitive. As every day, her dad is picking her up after school.

‘Daddy! I am so happy to see you!’
‘Bolla, you big ball of joy! How are you? Wanna go for a roll in the park?’
‘Yes, let’s go!’
‘Nice. How was school today?’
‘Good, good. I was just a bit sad about Prof. Shallot. We almost cannot hear his vibrations anymore.’
‘Oh, he is getting old. He has been teaching for many years. I am sure the school will soon assign him an amplifier.’
‘Ampli—what?’
‘An amplifier. It’s normally a young, vigorous ball that is sensitive enough to perceive weak vibrations from old people and can transmit them loudly to the student balls. The loudest ones can transmit to up to 10 balls in a chain.’
‘Oh, that would be nice! So they don’t split up our class.’

‘Also, daddy… the religion professor was talking strange today. He talked about this “infini… tari… mally… small” — but nobody understood what it is.’
‘Infinitesimally small. It’s difficult to explain, I am a bit surprised they teach it to such large balls. In my day, they only taught it when we had already shrunk a bit.’
‘But what it is, daddy? I want to know!’
‘Well… you know, as we age, we become smaller and smaller. But how small can we get? Some believe that at some point we get so small that we penetrate into the earth, and gravity pulls us down and down… until we reach the core of the planet, where we stay forever.’
‘That’s so sad… I don’t like that idea. And what do you believe, dad?’

‘I like to think that when we are very small we become like ants.’
‘But I can still see the ants!’
‘Yes, you silly sphere, but they have their own little ant world… and we know nothing about it! It’s like they live in another dimension. Then, over time, you become ten times smaller than an ant and I imagine that’s even another world. Then, even smaller… for infinity.’
‘Oooh, I see now. Maybe that’s also what the religion professor was trying to say. But still, why so tiny? I wish we could be like trees, who get bigger as they get older. Look at that tree down there, so big and beautiful! I also wish they spoke the same vibrations as us. Imagine how many stories they have to tell.’
‘That’s a beautiful thought, Bolla.’

‘Now I am a bit tired of staying still and vibrating. Could we go bounce a little?’
‘I wish — but your dad is getting old. With every bounce, my body aches more. You go ahead, I’ll catch up later.’

. . .

‘Daddy, I have one request… Can you please never get too tiny? Small is okay, but if you are tiny I cannot find you anymore — and I want to talk with you!’
‘Let’s go now, Bolla. It’s getting late. You know I don’t like rolling in the dark.’

In memory of Sofie.

One evening, about 12 years ago, her and I were chilling on her couch, having a great time inventing new planets. The ball planet excited us the most. I wish she could read this, and add to it. But she became a tiny ball in an instant, and nobody can see her anymore.