Mysteries of cosmology

- I’ve got a riddle for you, Kim. What are two things you can never eat for breakfast? - Don’t be silly, Philip! There are some real puzzles that need to be solved! Do you know what happens to a giant star when it burns out? When a giant star runs out of fuel, it collapses.

Its mass concentrates in a very small space of an extremely large density - a SINGULARITY. Gravitational force around the singularity is so big that it pulls in everything that comes too close, even light. This region of space is completely black, and that’s where it gets its name from - a BLACK HOLE. Black holes work a bit like a drain. Whatever stays far enough away is completely safe.

But if something goes over the “edge” - the EVENT HORIZON of a black hole - it falls into the hole and disappears from our sight. We know quite a lot about black holes already, but we can’t see or measure anything that’s inside them, past the event horizon. There are several theories, but until we find evidence, black holes will remain one of the unsolved mysteries of the universe. Another cosmological riddle emerged when scientists were studying the speed of rotating galaxies. Using all available knowledge they tried to predict the results of their measurements.

But once they measured the speed of different stars, they discovered that the predictions were wrong! - The stars move much faster than they should! In fact, moving at such a speed, the stars should in theory just fly out of the galaxy! How is it possible that they stay in place? Scientists figured that there must be more mass in the universe than planets, stars, asteroids and other objects we can see - some sort of invisible matter. They decided to name it DARK MATTER.

Dark matter is not like anything we see around us and it’s not made of anything we know. Unlike regular matter, dark matter doesn’t absorb or emit any radiation, which makes it impossible to observe. But it has mass and affects the visible matter, so there is strong evidence that it exists. It’s estimated that dark matter actually makes up more than 80% of all the matter in the universe! But we still don’t understand what it actually is, where it comes from and why there is so much of it.

Another unsolved mystery that puzzles astronomers has to do with the expansion of the universe. For a long time scientists were convinced that the gravitational forces should slow down the expansion. This theory was flipped upside down, when researchers proved that the universe is actually expanding faster and faster! This means that there must be some kind of force or energy stronger than the gravitational pull that increases the rate of expansion. This phenomenon was given the name of DARK ENERGY but nobody can explain exactly what it is or how it works.

What we know about the universe is based on what we can observe and confirm with calculations and mathematical models. Thanks to researchers, many mysteries of the universe have already been solved. We don’t have all the answers yet but who knows, maybe we’ll find them soon. - So, what are these two things you can’t eat for breakfast? - Lunch and dinner, hahahaha!