GARDEN OF PHYSICS: Where is the universe expanding?

Where is the universe expanding?
Guest: Tijana Radenković

People often ask: ’If the universe is expanding, where is it expanding?, says Tijana Radenković of the Institute of Physics, Belgrade in the tenth episode of the scientific-popular video series ’The Garden of Physics’ and explains that this question has a background in our intuitive way of thinking.

’If something is expanding, it is always at the expense of something else, it is expanding into some space. The issue with the universe is that space and time do not exist outside of it, so since it is it that is expanding, it is expanding into nothing’, states Radenković.

The expansion of the universe, according to the interlocutor, is one of the greatest discoveries of cosmology, and it was observed by Edwin Hubble in 1929 while he was watching the night sky and galaxies. Hubble analyzed the glow and colour of stars and noticed that farther stars appear redder than closer ones. ’He concluded that the universe was expanding by comparing distances of galaxies and the speed they are moving away from us’, elaborates Tijana Radenković.

The tenth episode of the series ’Garden of Physics’ is dedicated to the expansion of the universe and it talks about how the discovery came to pass, where the universe is expanding and what this phenomenon can lead to in the future.

Realized in cooperation with the portal ’Science Through Stories’, each episode of ’The Garden of Physics’ is dedicated to one of the fundamental topics of modern science, whether it is the greatest secrets of our times or research indicating unexpected horizons in the perception of the world. New episodes are aired every Friday online and they are available on webpages of the Institute of Physics, Belgrade and the portal „Science Through Stories“, as well as on You are welcome to join us.

Authors: Marija Đurić and Slobodan Bubnjević
Scenario: ’Science Through Stories’
Camera/drone: Zoran Veljanoski, Bojan Živojinović (Twotech Solutions)
Production associate: Jovana Nikolić
Directing and editing: Bojan Živojinović

Produced by: Insitute of Physics, Belgrade, 2020