And it isn’t Einstein’s equations… but it does come from them!
There are some incredibly big questions that humanity has been asking about the Universe since we first began looking upwards: what is the Universe like, how did it get to be this way, where did it all come from, and what is its eventual fate? There were huge advances that were needed in order to answer these questions, such as understanding what the Universe was made of, how fast it was expanding, and what the laws governing it were. But once we know that, not only can we answer these questions, but we can do it with a single equation. It’s known as the First Friedmann equation, and I call it the most important equation in the Universe.