The physics of observers

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?
Imagine if your body weight depended on the colour of your underwear. Strangely, something quite similar happens when you make measurements in quantum mechanics. Discover more about contextuality in this video interview with Jeremy Butterfield, philosopher of physics.
Quantum mechanics suggests that observers can influence the outcomes of measurements. If that's the case, then do these observers need to be conscious? Does consciousness play a special role in physics at all?
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. But does this sheer scale affect how we reason about cosmology? In this video interview, we talk to David Wallace to find out more.
Quantum mechanics seems to suggest that passive observation is impossible: the very act of looking at something can change what's being looked at. In this video interview, we talk to David Wallace and Adrian Kent to find out more.
Imagine your weight depended on the colour of your underwear! Something quite similar happens with measurements in quantum physics. Find out more here...
What does contextually mean for real-life measurements and what does it have to do with religious questions?
Imagine your weight depended on the colour of your underwear! Something quite similar may be happening when you are measuring things in quantum physics. Find out more here...