Measuring the expansion of the Universe: Dying stars may be telling us we're doing it wrong.

How fast is the Universe expanding?

This is one of the most fundamental questions in cosmology (the study of the origin and behavior of the Universe), let alone science itself. We've known for a century that it's expanding; observations of distant galaxies show they are all moving away from us, which is what you'd expect to see if you're inside an expanding cosmos. As space itself expands it carries galaxies along with it, and the farther away they are the more rapidly they move*.

Thing is, wh...