Philosophy of cosmology

Taking apart the CMB picture using the maths of sound.

Since he Universe is all there is, there's nothing for it to expand into. So what does "expansion" mean?

Some of the Universe's most important secrets are hidden in the shape of a beautiful undulating curve: the power spectrum of the cosmic microwave spectrum. This article explains how.

Find out all you need to know about the cosmic microwave background in this comprehensive overview.

To understand the why the cosmic microwave background tells us so much about the Universe, you first need to understand what created it: sound waves travelling through the early Universe.

The cosmic microwave background is the earliest light we can see in the Universe. So important is this baby picture of the Universe, it's been involved in two Nobel Prizes. Why?

When it comes to the entire cosmos, we humans are incredibly small and insignificant. But that's precisely why we need to take ourselves into account when thinking about the Universe. Find out why.

Traditionally, observers play no special role in physics. Like bird watchers in a perfect hide, we observe the outcome of experiments, or gaze at the stars through our telescopes, taking no part in the action. Modern physics, however, tells a different story ... find out more with these articles and videos.

Can the very act of observing something change what's being observed? This series of articles and videos explores some basic questions about the role of the observers in physics.

If there's a multiverse, then how many of its component universes are like our own?

What do we know about our Universe? And could there be more than one?