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Hello, something in our universe is missing, or rather almost everything, most of the matter in existence.

Scientists first noticed this in the 1930s observing that galaxies were moving much faster than expected and at such speed

should have dispersed or evaporated. They theorized that there must be something

as yet unknown keeping the galaxies in place. The Swiss astronomer Fritz Zwecki, call in the 1930s, called this missing matter at first

and later, as we know it now, Dark Matter.

At least one of our guests today claims that once we do know what Dark Matter is, we will

have solved one of the greatest mysteries in science, linking the Big Bang with the creation of galaxies,

planets, Earth and everything on it including us.

With me to discuss Dark Matter Hour,

Carolyn Crawford, public astronomer at the Institute of Astronomy,

University of Cambridge, and Gresham Professor of Astronomy. Anne Green, Reader in Physics at the University of Nottingham,

and Carlos Frank, Ogden Professor of Fundamental Physics and Director of the Institute for

Computational Cosmology at the University of Durham.

Caroline Crawford, what's the start of the story of the discovery of dark matter?

The primary evidence for dark matter is astronomical observations observations and as you said in your

introduction the story starts back in the 1930s with the astronomer Fritz

Vicky who was identifying classifying studying clusters of galaxies.

And a cluster of galaxies is where you have a whole swarm of galaxies.

You've got thousands, hundreds of thousands, all contained within a fairly small volume, a few millions of light years across, a few

tens of millions of light years across, and they're all bound together under their

...