Introduction to cosmology

For ages people have looked up to the sky and wondered - what is out there? Every civilization, culture and religion has had their own stories and ideas about the Earth and the universe. Philosophers and scientists have been trying to find the answers to questions about where everything comes from, what the universe is, what it's made of and how we fit in all this. Some have gone even further - not just looking at the past, but also trying to predict the future of the universe. All these questions about the origin, qualities and history of the cosmos led to the creation of a branch of science called COSMOLOGY.

Our understanding of the cosmos is limited to what we can observe and what we can calculate based on what we already know. It was new discoveries and technology that made us change our theories and assumptions several times in history, and come up with laws and principles that make up the modern scientific cosmology. Some major discoveries which contributed to the development of cosmology happened in the beginning of the 20th century. It begins with Albert Einstein and his General Theory of Relativity. When Einstein tries to apply his theory to the universe, he comes to a shocking discovery - The universe isn’t stable, as everyone has thought!

But apart from his equations he has no evidence to support this theory. Soon after that, American astronomer Edwin Hubble, realizes that there are galaxies other than the Milky Way. He focuses his studies on the light they emit and the distances between them. Simultaneously, Belgian priest and scientist Georges Lemaître observes that galaxies are constantly moving away from us and from each other. And the further away they are, the faster they move.

Hubble’s studies confirm Lemaître’s hypothesis and give evidence to Einstein’s equations. The universe is expanding. These findings lead to formulation of so called HUBBLE–LEMAÎTRE LAW, which is now a fundamental principle of modern cosmology. But Lemaître decides to go a step further and suggests that if the cosmos is expanding, it must have been much smaller in the past. He claims that it might have been as small as a single point without any dimension.

All matter, space and time, were once concentrated in this SINGULARITY. At some point the singularity started expanding, creating stars, planets, galaxies - the universe as we know it. This is what we call the BIG BANG THEORY. Even if it sounds unbelievable, observations and research done by scientists support this theory. Scientists continue to study the cosmos with the help of modern technology - computers, satellites and advanced telescopes.

The Very Large Telescope in Chile and the Hubble Space Telescope in the Earth’s orbit allow us to see clear images of stars and other celestial objects that are far away. Some of these stars are so far away that it takes an extremely long time for the light to reach the Earth. Because of that, looking at them, we actually look into the past of the universe! An even bigger telescope, the James Webb Space Telescope, is planned to launch into space. Scientists hope it will allow us to see the formation of the first galaxies and give us more clues about how the universe evolved.

Cosmology combines the knowledge from different areas of science with modern technology so that we can observe, analyze, and learn about the cosmos. There are still no definite answers to questions about the creation, evolution or future of the universe. But every day, research brings us closer to understanding it better.