What are extreme masses?

Extreme masses are objects that are either incredibly heavy or surprisingly light compared to what we usually see around us. Imagine a giant mountain or a tiny speck of dust.

Most things in our lives have a "normal" weight. A dog is heavy enough to pull you if it runs, but light enough for your dad to pick up. An apple falls perfectly into the trash can. But extreme masses break those normal rules. They are so big they change how gravity works nearby, or so small that the laws of physics start acting weird.

Think about the biggest thing you know: a skyscraper. Now imagine a building made of solid gold that stretches up to the clouds. That is an extreme heavy mass. In space, stars and black holes are like this. A black hole is so heavy that if you dropped a toy car onto it, it would squash flat instantly. It is like trying to jump on a trampoline that has a bowling ball sitting in the middle. The trampoline bends so much that everything rolls toward the ball.

On the other side, we have extreme lightness. Think about a single eyelash floating in the air. Or a bubble of soap drifting by. These are tiny masses. In the world of atoms, scientists study particles that weigh almost nothing. They are like ghosts compared to the bowling ball. Even though they are light, there are trillions of them!

So, extreme masses are just things at the very top and bottom of the weight scale. One group is so heavy it bends space, and the other is so light you might not even feel them unless you look closely. Both extremes help us understand how the universe holds together.