Cosmology: Who’s afraid of the bubbling broth? The mystery of the cosmological constant


Tony Padilla is a Professor of Physics and popular science author at the University of Nottingham. He recently published his first book Fantastic Numbers and Where to Find: a cosmic quest from zero to infinity where he takes readers on an irreverent journey in to the world of extreme physics and mind-blowing mathematics. He is also known as a regular presenter on two successful YouTube channels: Sixty Symbols and Numberphile, where his most popular videos include a discussion of Ramanujan’s sum of all positive integers which has been viewed more than 8  million times. Prior to his time at Nottingham, he held research positions at the University of Oxford and the University of Barcelona. He has published over 70 academic papers in leading academic journals and in 2016, he shared the Buchalter Cosmology Prize for his work on the cosmological constant problem. Outside of academia, he is an avid football fan and can often be found watching Liverpool Football Club from his regular seat on the Kop.

Who’s afraid of the bubbling broth? The mystery of the cosmological constant

You should not be reading these words.  They should not exist and neither should you. This is because the universe ought to have pushed itself into oblivion within an instant of being born. It should have been pushed by the quantum cacophony of empty space, a vacuum filled with a bubbling broth of virtual particles, weighing the universe down and bending it out of existence. At least thats what our calculations and our current understanding of fundamental physics tell us should have happened but it didn’t.  The universe is still here and so are you. But why? What is wrong in our microscopic understanding of the universe? What protects from the bubbling broth of empty space? This is the cosmological constant problem, often described as the most challenging question in fundamental physics. I will tell you the story of how it has arisen,  going all the way to the a conversation in a cafe in Hamburg in the mid 1920s, and a calculation that was scribbled onto a napkin. And I’ll tell you about some of the things we are thinking about almost a 100 years later.