Modern theories suggest that the Universe really is unimaginably large — perhaps it's infinite, but even if it's not, it's so large it may as well be. Some theories even suggest that we live in a multiverse, with individual universes constantly popping in and out of existence like bubbles in a bubble bath. But, ironically given our insignificance within the vast cosmos, we need to take ourselves into account when trying to understand the Universe.

"The sheer scale of the Universe affects how we reason about science," explains David Wallace, a philosopher of physics at the University of Oxford. "It affects the way we reason from observations to predictions as to which theories are true." Watch this video interview to find out more.

Explore more about the role of observers in physics with this package of articles and videos.