These lessons are for anyone who doesn’t know much about modern science. They give a quick and exciting look at how physics changed in the 20th and 21st centuries, and talk about the big questions and mysteries that came after.Lesson 1: The Most Beautiful TheoryWhen Albert Einstein was young, he liked to spend time just thinking and learning for fun. One day, he wrote three science papers that changed everything. One of them was about the “special theory of relativity.” Later, he worked hard for ten years to make a new theory that could explain gravity better. This became the “general theory of relativity,” which is called one of the most beautiful ideas in science. It says that gravity is not a force pulling things together, but instead, massive things like stars and planets bend space around them, and that’s why things fall or move in orbits. Even time itself can change depending on where you are!Lesson 2: QuantaAnother big change came with “quantum mechanics.” Scientists used to think everything was smooth and continuous, but Max Planck and later Einstein showed that energy and light come in tiny packets called “quanta.” Light is made of small particles called “photons.” Other scientists, like Niels Bohr and Werner Heisenberg, showed that tiny things like electrons don’t move in a straight line or stay in one place—they only show up in certain spots, and much of what happens is random, or based on chances. Quantum mechanics helps us understand things like computers and atoms, but it is still full of mysteries!Lesson 3: The Architecture of the CosmosFor a long time, people thought Earth was at the center of the universe. Later, they learned Earth goes around the Sun, and the Sun is just one of billions of stars in a huge galaxy. Our galaxy is just one of many in the universe. Scientists now know the universe started from a tiny, hot spot and has been growing ever since—that’s called the Big Bang.Lesson 4: ParticlesEverything we see is made of atoms. Atoms are made of protons, neutrons, and electrons. Protons and neutrons are made from even smaller things called “quarks.” There are only a few kinds of basic building blocks, like “electrons,” “quarks,” and “photons.” They all follow the strange rules of quantum mechanics. Scientists have discovered even more particles, like “neutrinos” and “Higgs bosons.” All these make up the “Standard Model,” which is the best explanation we have for how tiny pieces of the universe work. Still, some things, like “dark matter,” are still a mystery.Lesson 5: Grains of SpacePhysics has two main big ideas: general relativity and quantum mechanics. But these two don’t always fit together—they seem to argue with each other. Scientists are working on a new idea called “quantum gravity,” which tries to bring both together. One way is called “loop quantum gravity.” It says space is not smooth, but is made of super tiny “grains” or “atoms” of space. Even time might work in a new way at this small scale. Scientists are trying to find ways to test if this is true.Lesson 6: Probability, Time, and the Heat of Black HolesWhy does heat always go from hot to cold? It’s because of “probability”—there are more ways for things to get mixed up than to stay ordered. Time seems to move forward because of this. In black holes, scientists discovered that they are actually “hot” and give off a tiny bit of heat, which connects gravity, quantum physics, and heat together. But there are still many puzzles about time and how it works.00:00:00 FIRST LESSON – The Most Beautiful of Theories00:21:11 SECOND LESSON – Quanta00:35:36 THIRD LESSON – The Architecture of the Cosmos00:42:28 FOURTH LESSON – Particles00:56:21 FIFTH LESSON – Grains of Space01:13:59 SIXTH LESSON – Probability, Time, and the Heat of Black Holes01:37:28 IN CLOSING – Ourselves