Secondary source

Have you ever dropped a spoon and watched it clatter to the floor. Or thrown a ball into the air and seen it curve back down. That’s me at work. I’m the invisible super-glue of the universe. I keep your feet planted firmly on the ground so you don’t float off into the sky. I pull the rain from the clouds and guide rivers to the sea. You can’t see me, but you can feel me every second of every day. It’s like the whole world is giving you a gentle, constant hug, keeping you safe and sound. Can you imagine a world where your toys just floated away if you let them go. Before people knew my name, they just knew that things always, always fall down, never up. For a long time, I was a big mystery. What was this invisible string pulling everything together. Well, let me tell you my story. My name is Gravity, and I’m one of the most important rules of the whole universe.

For thousands of years, people just accepted that I did my job. But then, a very curious man came along. His name was Isaac Newton, and he loved asking 'why?'. One day, around the year 1666, he was sitting under a tree when he saw an apple fall to the ground. It wasn't the first time someone had seen an apple fall, of course, but it was the first time someone asked a truly brilliant question: If I can pull an apple from a tree, can I also reach all the way up to the Moon. He realized that I wasn't just a rule for things on Earth. I was universal. I am the very same invisible force that keeps the Moon from flying away from the Earth, and the Earth from wandering away from the Sun. On July 5th, 1687, he shared his big ideas in a famous book. He imagined me as a force, a pull that everything with mass has. The bigger something is, like a planet or a star, the stronger my pull. Then, more than two hundred years later, another super-thinker named Albert Einstein came along. He had an even wilder idea. On December 2nd, 1915, he explained that I wasn't just a pull, but a bend in the very fabric of the universe, which he called spacetime. Imagine stretching a big sheet out flat like a trampoline. That's spacetime. Now, place a heavy bowling ball in the middle. The sheet dips and curves, right. If you roll a marble nearby, it will follow that curve and circle around the bowling ball. That’s me. Planets and stars are like the bowling ball, and smaller things like moons and asteroids are the marbles, following the curves I make in the universe.

So, I am both a simple pull and a grand cosmic curve. I am the reason you can play catch, ride a scooter, or build a tower of blocks that doesn't float away. I am also the reason stars clump together to form sparkling galaxies, and planets dance in perfect orbits around their suns. Without me, the universe would be a cold, chaotic soup of floating bits and pieces. But because of me, it’s an organized, beautiful, and wonderful place. Understanding me has helped people send astronauts to the Moon and robots to Mars. Scientists are still studying my secrets, trying to understand my deepest mysteries, like black holes, where my pull is so strong that not even light can escape. I’m the silent force that shapes everything, from a falling raindrop to a spinning galaxy. I keep everything together, and I invite you to always stay curious and keep asking big questions about the amazing universe you live in.